TY - Generic T1 - Ultrasonic Snow Depth Sensor Refurbishment and Testing at the NRCS National Water and Climate Center Electronics Maintenance Facility, Portland, OR T2 - 86th Annual Western Snow Conference Y1 - 2018 A1 - Chris R. Brown AB -

The Natural Resources Conservation Service (NRCS) National Water and Climate Center (NWCC) Electronics Maintenance Facility (EMF) in Portland, OR provides assistance and guidance to the NRCS Snow Survey and Water Supply Forecasting program regarding the use of electronic instrumentation to collect hydrologic and climatic data at SNOTEL (Snow Telemetry) and SCAN (Soil Climate Analysis Network) sites. Snow depth is an important component measured at SNOTEL sites. The most common sensor used to measure snow depth within the SNOTEL program is the ultrasonic snow depth sensor. Ultrasonic snow depth sensors are to be refurbished and tested at EMF or replaced every six years. When a snow depth sensor is returned to EMF, all the major electronic components, along with any degenerate sensor body components, are replaced by technicians, and the refurbished sensor is run through a ten-point test to ensure that it meets manufacturer and programmatic specifications. Sensors that meet specifications are redeployed at SNOTEL sites and field-checked annually. (KEYWORDS: SNOTEL, snow depth, direct snow measurement, instrumentation)

JF - 86th Annual Western Snow Conference CY - Albuquerque, New Mexico UR - /files/PDFs/2018Brown.pdf ER - TY - Generic T1 - On the Use of Snow and Climate Information in Statistical Seasonal Streamflow Forecasting T2 - 86th Annual Western Snow Conference Y1 - 2018 A1 - Flavio Lehner A1 - Andrew W. Wood A1 - Dagmar Llewellyn A1 - Douglas B. Blatchford A1 - Angus G. Goodbody A1 - Florian Pappenberger AB -

Seasonal streamflow predictions provide a critical management tool for water managers in the American Southwest. These forecasts rely primarily on observations of snowpack and precipitation accumulation, which help to quantify the hydrologic memory that enables relatively accurate streamflow forecasts at seasonal lead times. In recent decades, persistent prediction errors for spring and summer runoff volumes have been observed in a number of watersheds in the American Southwest. While mostly driven by interannual to decadal precipitation variability, these errors also relate to the influence of increasing temperature on snow and streamflow in these basins. Here we show that incorporating seasonal temperature forecasts from operational global climate prediction models into streamflow forecasting models adds prediction skill for watersheds in the headwaters of the Colorado and Rio Grande River basins. Current dynamical seasonal temperature forecasts now show sufficient skill to reduce streamflow forecast errors in snowmelt-driven and temperature-sensitive basins. Such predictions can increase the reliability of streamflow forecasting and water management systems in the face of continuing warming as well as decadal-scale temperature variability, and thus help to mitigate the impacts of climate non-stationarity on streamflow predictability.

JF - 86th Annual Western Snow Conference CY - Albuquerque, New Mexico UR - /files/PDFs/2018Lehner.pdf ER - TY - Generic T1 - Uncertainty in the Future of Seasonal Snowpack Over North America T2 - 86th Annual Western Snow Conference Y1 - 2018 A1 - Rachel R. McCrary A1 - Linda O. Mearns AB -

Snow cover extent and snow water equivalent (SWE) are rapidly changing over North America. This study investigates the uncertainty in the projected changes in North American snow cover for the middle of the 21st century using the North American Regional Climate Change Assessment Program (NARCCAP) ensemble of dynamically downscaled regional climate models (RCMs). Across the NARCCAP models, temperature is projected to increase everywhere while precipitation is shown to increase everywhere except the western U.S. In this region, the NARCCAP models disagree on the sign of the change in precipitation during the Fall and Winter. Corresponding with these changes in temperature and precipitation, the NARCCAP models robustly show that SWE is projected to decrease over most of North America. The only exception to this is in the high-latitudes, where SWE is projected to increase during the coldest months corresponding with increases in precipitation. There is considerable uncertainty in the magnitude of changes in SWE over north America, especially in the west. Variations in magnitude correspond with baseline SWE amounts from the current climate simulations as well as variations in the drivers of the change, namely temperature and precipitation. Changes in temperature and precipitation also lead to changes in the timing of the snow cover season. The first snow covered date is projected to occur later in the fall while the last snow-covered date is shown to occur earlier in the spring. These shifts result in a reduction in the total number of snow-covered days. There are notable differences across the ensemble in the change in the number of snow-covered days in the western US. Also, changes in the first and last dates with snow cover are uncertain in the central plains of North America, primarily due to interannual variability in this region. (KEYWORDS: North American snow cover, snow water equivalent, climate change, climate models, NARCCAP)

JF - 86th Annual Western Snow Conference CY - Albuquerque, New Mexico UR - /files/PDFs/2018McCrary.pdf ER - TY - Generic T1 - Using Ground Penetrating Radar to Assess the Variability of Snow Water Equivalent And Melt in a Mixed Canopy Forest T2 - 85th Annual Western Snow Conference Y1 - 2017 A1 - Ryan Webb AB -

Snow is an important environmental variable in headwater systems that controls hydrological processes
such as streamflow, groundwater recharge, and evapotranspiration. These processes will be affected by both the
amount of snow available for melt and the rate at which it melts. In complex mountainous terrain, a number of
factors can affect snow water equivalent (SWE) and melt including slope, aspect, canopy type, and canopy density.

JF - 85th Annual Western Snow Conference CY - Boise, Idaho UR - /files/PDFs/2017Webb.pdf ER - TY - Generic T1 - Using Snow Water Equivalent Reconstruction for Operational Use: Two Case Studies T2 - 84th Annual Western Snow Conference Y1 - 2016 A1 - Edward H. Bair A1 - Karl Rittger A1 - Carrie Vuyovich A1 - Bruce McGurk A1 - Jeff Dozier AB -

In the snow water equivalent (SWE) reconstruction method, the snowpack is built up in reverse from downscaled energy balance forcings and satellite-based estimates of fractional snow covered area (fSCA). For melt modeling, we have developed a full energy balance model called ParBal that relies on satellite-based measurements and does not need ground-based inputs. Using ParBal to compute the melt, SWE reconstruction has been shown to be accurate when compared with a variety of validation sources, most recently by comparison with Airborne Snow Observatory (ASO, Painter et al., 2016) measurements in the Upper Tuolumne Basin, CA USA (Bair et al., 2015; Bair et al., in review). The major disadvantage is that reconstructed SWE estimates are only available retrospectively. While this limitation cannot be overcome, we present two case studies where reconstructed SWE can be used in an operational context. 1) We run ParBal as a melt only model, examining seasonal and daily melt without reconstructing the snowpack. Although we cannot reconstruct snow on the ground in this manner, we can potentially make near real-time estimates of snowmelt if these daily melt estimates are then fed through a routing model and compared with streamflow measurements. ParBal can be driven by: a) Global Data Assimilation System (GDAS, Kleist et al., 2009) meteorological forcings, now available at 1/9° spatial resolution and at 3 hr intervals with almost no latency; and b) Moderate Resolution Imaging Spectrometer Snow Covered Area and Grain Size (MODSCAG, Painter et al., 2009) snow cover data, available daily with one or two day latency. 2) We use machine learning techniques to build statistical relationships between remotely-sensed products, such as the ones mentioned in 1), and reconstructed SWE in Afghanistan. This approach allows real-time SWE prediction in remote areas that previously had little or no baseline for comparison

JF - 84th Annual Western Snow Conference CY - Seattle, Washington UR - /files/PDFs/2016Bair.pdf ER - TY - Generic T1 - Understanding the Spatial Distribution of Snow Water Equivalent in Paired Basins in Southwest Montana, USA T2 - 83rd Annual Western Snow Conference Y1 - 2015 A1 - Jason Welz A1 - Jordy Hendrikx A1 - Stuart Challender A1 - Paul Stoy KW - avalanche KW - binary regression tree KW - paired basin KW - Snow water equivalent KW - spatial distribution AB -

The goal of this research, which was the focus of a master’s thesis, was to build upon previous investigations of the processes controlling the spatial distribution of snow water equivalent (SWE) in alpine environments. This involved taking a comprehensive look at the widely accepted physiographic variables of: elevation, slope, aspect, solar radiation, and wind exposure, but also avalanche activity, which has been given limited explicit inclusion. The paired basin design adopted in this study, between hypothesized avalanche-prone and avalanche-free basins, has been previously used to correlate avalanche activity with snowmelt runoff. However, it has not been used in an attempt to parse out which variables have the dominant influence on SWE distribution between adjacent areas of very similar physiographic character. While most previous studies have focused on the period of peak SWE to study its distribution, this current research considered the evolution of the controlling variables throughout snowpack development, and subsequent melt-out. A robust dataset of snow depth and SWE measurements were collected January 31 - July 10, 2013 on Cedar Mountain near Big Sky, MT. Physiographic variable values were extracted from a 10 m resolution digital elevation model (DEM) at snow sample points and input as predictors of observed SWE in multiple linear regression (MLR) and binary regression tree (BRT) models to spatially distribute SWE across the study area. Optimal models were selected by various measures of goodness of fit and cross-validation criteria. Calculated R2 values for MLR models (0.17-0.57) and BRT models (0.33-0.66) were comparable to previous studies indicating a relative level of success in predictive performance. Subsequent analysis of each optimal model’s variable selection and predicted SWE distributions revealed differences in the spatial and temporal patterns of this metric between the paired basins, confirming some well-understood processes as well as offering new insights.

 

Presentation in PDF

JF - 83rd Annual Western Snow Conference T3 - Proceedings of the Western Snow Conference CY - Grass Valley, California UR - /files/PDFs/2015Welz.pdf ER - TY - Generic T1 - Use of Snow Data From Remote Sensing in Operational Streamflow Prediction T2 - 82nd Annual Western Snow Conference Y1 - 2014 A1 - Stacie Bender A1 - Paul Miller A1 - Brent Bernard A1 - John Lhotak KW - operational hydrology KW - remote sensing KW - snow observations KW - snowmelt forecasting KW - Streamflow forecasting AB -

The Colorado Basin River Forecast Center (CBRFC) issues operational forecasts of streamflow for the Colorado River Basin and eastern Great Basin. As part of a multi-year collaborative effort, CBRFC has partnered with the research-oriented Jet Propulsion Laboratory (JPL) under funding from NASA to incorporate remotely sensed snow data from NASA’s MODIS instrument into operational hydrologic forecasting and modeling at CBRFC. Snowpackconditions indicated by MODIS informCBRFC forecasters when determining causes of divergence between modeled and recently observed streamflow. The first two years of the collaborative partnership have yielded improved forecasts at select locations, in select cases, using information from remotely sensed snow data. CBRFC and JPL also retrospectively analyzed relationships between the MODIS-derived snow datasets and streamflow patterns for several watersheds within CBRFC region. The collaboration is expected to continue over the next several years as CBRFC and JPL work to further improve modeling of snowmelt and prediction of snowmelt-driven streamflow in operational hydrologic forecasting.

JF - 82nd Annual Western Snow Conference T3 - Proceedings of the Western Snow Conference CY - Durango, Colorado UR - sites/westernsnowconference.org/PDFs/2014Bender.pdf ER - TY - Generic T1 - Understanding Trends in Snow Accumulation and Streamflow Using Snow Telemetry and Streamgage Observations in the Missouri River Headwaters T2 - 82nd Annual Western Snow Conference Y1 - 2014 A1 - Thomas Matthews A1 - Jordy Hendrikx KW - ENSO KW - precipitation KW - runoff KW - snow KW - temperature KW - water availability AB -

The Missouri River headwaters are located in the mountains of southwestern Montana and drain the eastern side of the continental divide. These headwaters serve as a water source for the Missouri River basin, which covers 10 states with an approximate population of 12 million people. A key component of the annual water budget in the headwaters is from snowfall, accounting for around 70% of the total annual flow in this region. The Western U.S. is generally comprised of semi-arid to arid regions that exhibit a high degree of inter-annual to multi-decadal variability. Changing trends in water availability due to climate change and yearly variations must be understood and quantified for proper allocation and forecasting of water resources. Here we use snow, temperature and precipitation records from the Natural Resource Conservation Service (NRCS) and streamflow records from the U.S. Geological Survey (USGS) in a coupled analysis designed to assess recent changes in these temperature sensitive high alpine headwaters over the last 40 years of record. Snow water equivalence, streamflow and temperature are key metrics that are indicative of changes in these headwater regions and are useful in determining the amount, timing and duration of hydrologically important snow-driven events. These data are being examined to determine what role inter annual and decadal drivers such as the El Niño Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the Pacific/North American Pattern (PNA) play in controlling the amount and timing of water availability in this catchment. Metadata from the weather stations used in this study are being analyzed to determine how changes in station characteristics, such as vegetation growth or equipment updates, can help explain variances in trends or relationships seen in the data beyond large-scale climate variations.

JF - 82nd Annual Western Snow Conference T3 - Proceedings of the Western Snow Conference CY - Durango, Colorado UR - sites/westernsnowconference.org/PDFs/2014Matthews.pdf ER - TY - Generic T1 - Understanding the Spatial Distribution of Snow Water Equivalent and Subsequent Snowmelt Runoff Patterns of Paired Basins in Southwest Montana T2 - 82nd Annual Western Snow Conference Y1 - 2014 A1 - Jason Welz A1 - Jordy Hendrikx A1 - Stuart Challender A1 - Paul Stoy KW - avalanche KW - mountain hydrology KW - runoff KW - Snow water equivalent KW - snowmelt AB -

This paper presents the initial results of a research project with the primary goal of investigating the hydrologic role of avalanche activity alongside the physiographic variables (i.e. elevation, slope, aspect, wind shelter/exposure, landcover, and solar radiation) that the snow hydrology community widely consider to be the dominant controls on the spatial distribution of snow water equivalent (SWE) and subsequent snowmelt runoff in alpine basins. An extensive field campaign was conducted in two adjacent alpine basins in southwest Montana from January 31 to August 21, 2013, consisting of three survey periods to capture snowpack metrics during the phases of (1) accumulation; (2) peak SWE, and (3) ablation/snowmelt runoff. During each period, the same stratified random sampling methods were used to measure snow depth and SWE at transects along elevation contours. Transects were spatially distributed with the goal of acquiring a representative sample of the aforementioned physiographic variables as well as the components of avalanche paths. After quantifying the contribution of each of these variables to the distribution of SWE, we will also consider their impact on the timing and magnitude of snowmelt runoff. This will be determined by correlation to stream discharge measurements that were collected throughout the 2012- 2013 water year. The initial results are discussed as are the future steps.

JF - 82nd Annual Western Snow Conference T3 - Proceedings of the Western Snow Conference CY - Durango, Colorado UR - sites/westernsnowconference.org/PDFs/2014Welz.pdf ER - TY - Generic T1 - Using Hydrochemistry Data to Constrain the Role of Snow and Ice Meltwater in the Langtang Valley, Nepal T2 - 82nd Annual Western Snow Conference Y1 - 2014 A1 - Alāna M. Wilson A1 - Mark W. Williams A1 - Rijan B. Kayastha KW - EMMA KW - glacier and snow melt KW - hydrochemistry KW - Hydrologic mixing models AB -

The Langtang River Basin of central Nepal is one of the most well-studied valleys of the Himalaya. With an elevation range of 1460m to 7246m and with the Upper Langtang Basin (above 3642m) approximately 40% glacierized, snow and ice melt play a dominant role in the hydrology. Presented here is a synoptic survey of hydrochemistry data from a pre-monsoon field campaign in May 2012. Major chemistry and isotopes are used to conduct hydrograph separations of the Langtang River to quantify the role of meltwater in river discharge. Results using End Member Mixing Analysis (EMMA) showa decline in the contribution of groundwater with increasing elevation - estimated at 24% at 1479m, down to 9% at 3642m. This work isolated contributions of 'high-elevation' water but EMMA did not identify distinct snow and ice contributions. Two versions of EMMA are compared – one including δ18O in the input tracer set and the second excluding it. EMMA results are compared to a two-component mixing model using δ18O as the sole tracer to separate groundwater from melt water. Ourobjective is to distinguish potential source waters through hydrograph separation. We show that using hydrochemistry data for EMMA can be an appropriate tool for this.

JF - 82nd Annual Western Snow Conference T3 - Proceedings of the Western Snow Conference CY - Durango, Colorado UR - sites/westernsnowconference.org/PDFs/2014Wilson.pdf ER - TY - Generic T1 - Understanding Trends in Snow Accumulation, Water Availability, and Climate Changes Using Snow Telemetry and Streamflow Observations in the Missouri River Headwaters T2 - 81st Annual Western Snow Conference Y1 - 2013 A1 - Matthews, Tom KW - climate KW - Missouri KW - SNOTEL KW - snow hydrology KW - temporal trends AB -

The Missouri River headwaters are located in the mountains of southwestern Montana, and serve as a water source for 10 states and approximately 10 million people. A key component of the annual water budget in this headwater region is from snowfall, accounting for around 70% of the total annual flow. The Western U.S. is comprised of semi-arid to arid regions that exhibit a high degree of inter-annual to multi-decadal variability. Changing trends in water availability due to climate change and yearly variations must be understood and quantified for proper allocation and forecasting of water resources. Here we use snow, temperature and precipitation records from the Natural Resource Conservation Service (NRCS) and streamflow records from the U.S. Geological Survey (USGS) in a coupled analysis designed to assess recent changes in these temperature sensitive high alpine headwaters over the last 40 years of record. Snow water equivalence, snow depth, temperature and streamflow are key metrics that are indicative of changes in these headwater regions and are useful in determining the amount, timing and duration of hydrologically important snow-driven events. These data are being examined to determine what role inter annual and decadal drivers such as the El Niño Southern Oscillation (ENSO), the Pacific North American Pattern (PNA), and the Pacific Decadal Oscillation (PDO) play in controlling the amount and timing of water availability in this catchment. Metadata from the weather stations used in this study are being analyzed to determine how changes to the station, such as vegetation growth or equipment updates, could help explain any trends or relationships seen in the data beyond the natural climate variations.

JF - 81st Annual Western Snow Conference T3 - Proceedings of the Western Snow Conference CY - Jackson Hole, Wyoming UR - sites/westernsnowconference.org/PDFs/2013Matthews.pdf ER - TY - Generic T1 - Using the Utah Energy Balance Snow Melt Model to Quantify Snow and Glacier Melt in the Himalayan Region T2 - 81st Annual Western Snow Conference Y1 - 2013 A1 - Avirup Sen Gupta A1 - Tarboton, David G. KW - Energy balance KW - glacier and snow melt KW - model KW - remote sensing AB -

Quantification of the melting of glaciers in the Hindu-Kush Himalayan (HKH) region is important for decision making in water sensitive sectors, and for water resources management and flood protection. Access to and monitoring of the glaciers and their melt outflow is challenging, thus modeling based on remote sensing offers the potential for providing information to improve water resources decision making and management. In this paper we report on a distributed version of the Utah Energy Balance (UEB) snowmelt model, referred to as UEBGrid, which was adapted to quantify the melting of glaciers taking advantage of NASA remote sensing and earth science data products such as, satellite data, reanalysis data and climate model outputs. The representations of surface energy balance fluxes in the UEB snowmelt model have been extended to include the capability to quantify glacier melt. To account for clean and debris covered glaciers, substrate albedo determined from remote sensing, and glacier mapping is taken as an input. Representation of glaciers within the model involves inclusion of glacier ice as a substrate and generation of melt from the ice substrate when seasonal snow has melted. In UEBGrid, a watershed is divided into a mesh of grid cells and the model runs individually for each grid cell. Users have control to provide separate inputs for each grid cell, or spatially constant inputs for the entire domain. Therefore, regional variability in snow and glacier melting is computed. Outflow can be aggregated over subwatersheds defined, for example, from a digital elevation model, and input into other hydrologic models. UEBGrid was tested using weather, climate and hydrologic data at Langtang Khola Watershed, Nepal. UEBGrid is being included into the EPA BASINS software to facilitate linking to other models and to take advantage of BASINS’s capability to manage input data and visualize results. This capability for using gridded NASA Earth Science data, and the associated data model and workflow for storage and processing of data into and out of models linked in BASINS advances hydrologic information science. The capability for estimating the melt from glaciers and snow in a data sparse region will help water managers in decision making and management of water resources in areas impacted by glacier and snow melt.

JF - 81st Annual Western Snow Conference T3 - Proceedings of the Western Snow Conference CY - Jackson Hole, Wyoming UR - sites/westernsnowconference.org/PDFs/2013SenGupta.pdf ER - TY - Generic T1 - Using Quantile Regression to Model Elevation/SWE Relationships in the Olympics and Central Washington Cascades T2 - 79th Annual Western Snow Conference Y1 - 2011 A1 - McDonald, S. A1 - Barry, D. KW - Washington Cascades, snow water equivalent, quartile regression, watershed elevation, least squares regression, Dungeness Watershed AB - Although ordinary least squares (OLS) regression is often used to develop initial models for elevation/snow water equivalent (SWE) relationships in watersheds, such an approach cannot account for the heterogeneous variability in SWE over elevation bands common in many coastal Pacific Northwest watersheds. This is particularly problematic in attempting to model middle-elevation SWE in watersheds affected by winter rain-on-snow events. Scatterplots of this relationship often show a distinctive fan-shaped pattern that widens as elevation increases, implying that there is not a single rate of change in SWE by elevation. Thus, the use of an OLS regression in models or trend assessment could provide severely misleading estimates of SWE in middle elevation areas where no field data are collected. We compare OLS and quantile regression-based models of SWE by elevation based on four snow seasons of field assessment for the Dungeness Watershed of western Washington State, as well as for snow courses and SNOTEL sites in the Olympic Mountains and central Washington Cascades. In both cases, quantile regression better accounts for the observed data than does the typical OLS approach. JF - 79th Annual Western Snow Conference T3 - Proceedings of the 79th Annual Western Snow Conference PB - Western Snow Conference CY - Stateline, NV UR - sites/westernsnowconference.org/PDFs/2011McDonald.pdf ER - TY - Generic T1 - Use of Radar for Spatial Snow Mapping: Implications for Water Supply Forecasts T2 - 79th Annual Western Snow Conference Y1 - 2011 A1 - Valsiloff, S. A1 - Busto, J. A1 - Arthur, A. KW - Radar, SNOTEL, snowpack assessment, runoff forecasting, San Juan Mountains AB - Water supply forecasts in the West rely largely on data from over 700 SNOw TELemetry (SNOTEL) sites in the Western United States. Forecast methodology is based on 30-yr regression periods using SNOTEL and measured run-off. However, SNOTEL data represent point values and are rarely sufficiently clustered to depict the true 3-dimensional spatial distribution of snowfall. Furthermore, many headwaters basins do not have SNOTEL sites. Thus the lack of observations can result in large uncertainties in the forecasts. This paper presents a case study from a gap-filling radar project that targeted the San Juan Mountains in Southwest Colorado. For the Animas River Basin the additional radar observed a 10-fold increase in the snow water equivalent compared to surrounding NEXRAD radars. In addition the radar depicted the spatial distribution of precipitation. While the location of the radar was not optimal, radar quantitative precipitation estimates were very similar to SNOTEL precipitation amounts at most SNOTEL locations. JF - 79th Annual Western Snow Conference T3 - Proceedings of the 79th Annual Western Snow Conference PB - Western Snow Conference CY - Stateline, NV UR - sites/westernsnowconference.org/PDFs/2011Vasiloff.pdf ER - TY - Generic T1 - Ultrasonic Snow Depth Sensor Accuracy, Reliability, and Performance T2 - 76th Annual Western Snow Conference Y1 - 2008 A1 - Anderson, J. A1 - Wirt, J. KW - Snow depth sensor, SNOTEL, NRCS, Idaho, sensor reliability AB - The Natural Resources Conservation Service Snow Survey Data Collection Office (DCO) in Boise, Idaho began installing Judd Communications Snow Depth Sensors in the late-1990s. Since that time the number of SNOTEL sites in the DCO with snow depth sensors has increased to 76 out of a total of 117 sites. Over the years 348 depth sensor ground truth measurements have been made each time snow water equivalence was measured at a site. Telemetered SNOTEL snow depths compare very well with manually sampled depths with a high degree of accuracy (R2 = 0.98). To test the reliability of the sensor during the accumulation phase of winter, hourly data between 12/1/2007 - 3/20/2008 were analyzed to determine the number of missed measurements (full-scale readings). Results showed that out of 228,798 hourly readings, 14% were full-scale. No clear relationship was found between the age of the depth sensor and its reliability. In 1999 the Idaho DCO began editing daily snow depth data. This editing process has provided an opportunity to observe the performance of depth sensors. Performance related to damaged transducers, transducer obstruction, wind effects, sensor misalignment and storm effects are discussed. JF - 76th Annual Western Snow Conference T3 - Proceedings of the 76th Annual Western Snow Conference PB - Western Snow Conference CY - Hood River, OR UR - sites/westernsnowconference.org/PDFs/2008Anderson.pdf ER - TY - Generic T1 - Untangling Climate and Wildfire Influences from Snow Water Equivalent Measurements on the Deer Park, Washington Snow Course T2 - 76th Annual Western Snow Conference Y1 - 2008 A1 - Drake, E. A1 - DeSisto, C. A1 - McDonald, S. A1 - Evans, S. A1 - Barry, D. A1 - Baccus, B. KW - Deer Park fire, Olympic National Park, snow course, SWE, PDO, ENSO, snowpack decline AB - In 1988, the Deer Park Fire burned 170 acres within Olympic National Park, WA. The wildfire burned up to the southern end of the NRCS/NPS Deer Park Snow Course. The burn eliminated a forest stand downwind and down-slope of the snow course; this study reports on a potential decline in snow water equivalent (SWE) measured by the course as a result of this adjacent change in forest cover. Regional climate trends based on Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) were incorporated into the evaluation, allowing the wildfire's impacts to be isolated from climatic variability. A comparison of mean SWE values before (1949-1988) and after (1989-2007) the wildfire for every reporting month in every climate cycle showed a clear trend of a decline after the wildfire; these differences are statistically significant in April and May for all climate cycles except for positive PDO+negative ENSO. Overall, estimates of effect size of the difference between means were uniformly negative and as low as 2.9 for February 1 snowpack in warm, dry climate cycles and as high as 17.1 for May 1 snowpack in cool, wet climate cycles. JF - 76th Annual Western Snow Conference T3 - Proceedings of the 76th Annual Western Snow Conference PB - Western Snow Conference CY - Hood River, OR UR - sites/westernsnowconference.org/PDFs/2008Drake.pdf ER - TY - Generic T1 - Uses of Natural Resources Conservation Service Snow Survey Data and Products T2 - 75th Annual Western Snow Conference Y1 - 2007 A1 - Abramovich, R. KW - Snowpack, predictability, SNOTEL, snow accumulation, water supply AB - In the Western U.S., the annual accumulation of the mountain snowpack and the resulting predictability of streamflow have created a wide range and diverse use of Natural Resources Conservation Service (NRCS) Snow Survey data and products. The key factor in the West is how much snow falls and where it falls for water users to speculate what may happen and plan accordingly. Historically, the NRCS inventoried the mountain snowpack to predict spring and summer streamflow for irrigated agriculture. The installation of the SNOTEL (SNOw TELemetry) Network in the early 1980s and a daily climatic data set has increased the use of this high elevation data. Many customers use this data to assist in their day-to-day decisions, for winter or summer recreation, to hedge financial decisions, or for wise management of water as a natural resource. This paper discusses the importance of snow in the West, how it accumulates, and melts to provide our water supply, and associated decisions made each season to manage and plan accordingly based on the winter snowfall. A seasonal timeline illustrates when customers need and use Snow Survey data and products. The obvious, but also unusual uses of snow survey data and water supply products are discussed. JF - 75th Annual Western Snow Conference T3 - Proceedings of the 75th Annual Western Snow Conference PB - Western Snow Conference CY - Kailua-Kona, HI UR - sites/westernsnowconference.org/PDFs/2007Abramovich.pdf ER - TY - Generic T1 - Using the WINWRNSHYD program as a didactic tool T2 - 73rd Annual Western Snow Conference Y1 - 2005 A1 - Swanson, R.H. KW - WRENSS, WRNSHYD, WinWrnsHyd, snow accumulation, forest management, peak flow changes AB - The WinWrnsHyd computer program is a complete implementation of the hydrology section of the USEPA WRENSS procedure plus some additional routines related to forest growth. As such its principal use has been to estimate the changes in water yield associated with forest management activities. However, it is not limited to this use. Forest harvest affects water yield by altering evapotranspiration, the differential accumulation and retention of snow, the timing of snow melt, the intensity of harvest, and the speed of vegetative regrowth. The WinWrnsHyd model simulates the magnitude of each of these factors and integrates the net result to give an estimate of annual water yield. Hydrologists often examine each of these factors in isolation and it is not always clear what magnitude of the effect that each one has on the integrated whole. JF - 73rd Annual Western Snow Conference T3 - Proceedings of the 73rd Annual Western Snow Conference PB - Western Snow Conference CY - Great Falls, MT UR - sites/westernsnowconference.org/PDFs/2005Swanson.pdf ER - TY - Generic T1 - Using Ensemble Streamflow Prediction for Water Supply Forecasting in British Columbia - Practicalities and Pitfalls T2 - 71st Annual Western Snow Conference Y1 - 2003 A1 - Smith, S. A1 - Weber, F. KW - ESP, forecasting, water supply, British Columbia, BC Hydro, UBC AB - BC Hydro has just completed new watershed model calibrations for 20 of its reservoirs, which would enable the use of Ensemble Streamflow Prediction (ESP) techniques for preparing water supply forecasts. ESP methods have been used to forecast the seasonal water supply for BC Hydro's large interior snow-driven basins for a number of years with much success. But using the technique for smaller coastal rain- and rain/snow-driven basins has proven to be much more challenging. This paper will focus on two known issues: snowpack simulation in the model and month-to-month model calibration bias. This study showed that in coastal and interior basins, snowpack adjustments improved the forecast accuracy and slightly decreased the dispersion. The bias correction technique computed daily bias correction offsets as differences between simulated and observed flows during the calibration period. The offsets were then applied to the ensembles of the forecast. The technique produced mixed results. JF - 71st Annual Western Snow Conference T3 - Proceedings of the 71st Annual Western Snow Conference PB - Western Snow Conference CY - Scottsdale, Arizona UR - sites/westernsnowconference.org/PDFs/2003Smith.pdf ER - TY - Generic T1 - USING GIS TO PREDICT THE SPATIAL DISTRIBUTION OF PERENNIAL SNOW UNDER MODERN AND LATE PLEISTOCENE CONDITIONS IN TIlE SNAKE RANGE, NEVADA T2 - 69th Annual Western Snow Conference Y1 - 2001 A1 - Orddorff, R.L. A1 - Van Hoesen, J.G. KW - GIS, Snow covered area, Spatial distribution AB - ELApse is a climate-driven snow and ice model developed to estimate the spatial distribution of perennial snow and ice in alpine systems. The snow model computes monthly snowfall, snowmelt, and resulting snowpack at each grid cell, and it estimates the densification of perennial snowpack and its transformation into glacial ice when appropriate. The model proceeds year-by-year until monthly snow and ice totals equilibrate. ELApse is sensitive to latitudinal and elevational controls on climate, but it is insensitive to subtle variations in the land surface that create microclimates that tend to preserve snow and ice. We use ArcView GIS to identify terrain characteristics (such as shading, slope, and curvature) that enhance accumulation and preservation of snow and ice. ELApse estimates of modem perennial snow extent in the high peaks of the southern Snake Range, NV are greatly improved by GIS postprocessing. In addition to modern solutions, we estimate the spatial distribution of perennial snow for temperature perturbations of -2C, -4C, and -6C. JF - 69th Annual Western Snow Conference T3 - Proceedings of the 69th Annual Western Snow Conference PB - Western Snow Conference CY - Sun Valley, Idaho UR - sites/westernsnowconference.org/PDFs/2001Orddorff.pdf ER - TY - Generic T1 - USGS research on three mid-latitude glaciers T2 - 68th Annual Western Snow Conference Y1 - 2000 A1 - Green, J.R. A1 - Cecil, L.D. A1 - Naftz, D.L. A1 - Schuster, P.F. KW - Climate change, Geochemistry, Glaciers, Modeling, Paleoclimate AB - Low- and mid-Iatitude regions of the earth are home to 80 to 90 percent of the world's population. Because of this, the U.S. Geological Survey (USGS) is conducting a research program to study the geochemistry of precipitation' snow, ice, and runoff samples from mid-latitude glaciers in Kyrghyzstan, Nepal, and the United States. Areas of research, such as ground-water studies, reconstructing paleoclimate records, describing anthropogenic input of chemicals to the environment, and modeling global climate change, are important to the well being of the worlds' population and can be supplemented by the collection and chemical analysis of snow and ice cores. Nearly all the constituents that compose snow and ice-core samples contribute vital information, whether it be the microbial communities that flourish in snow, radionuclides present in various amounts in all the samples, or location-specific deposits of mercury and nitrate. This work is hastened by the fact that mid-Iatitude glaciers, and the information preserved in them, are rapidly disappearing as a result of global warming. Research collabomtion for this project includes 12 national and 7 international universities, and 4 government agencies. Funding is provided by the National Science Foundation, the U.S. Department of Energy, and the USGS. JF - 68th Annual Western Snow Conference T3 - Proceedings of the 68th Annual Western Snow Conference PB - Western Snow Conference CY - Port Angeles, Washington UR - sites/westernsnowconference.org/PDFs/2000Green.pdf ER - TY - Generic T1 - Using geostatistical methods to estimate snow water equivalence distribution in a mountain watershed T2 - 66th Annual Western Snow Conference Y1 - 1998 A1 - Balk, B. A1 - Elder, K. A1 - Baron, J. KW - Snow accumulation, Snow covered area, Snow density, Snow depth, Statistical analysis AB - Knowledge of the spatial distribution of snow water equivalence (SWE) is necessary to adequately forecastthe volume and timing of snowmelt runoff. In April 1997, peak accumulation snow depth and density measurements were independently taken in the Loch Vale watershed (6.6 km2), Rocky Mountain National Park, Colorado. Geostatistics and classical statistics were used to estimate SWE distribution across the watershed. Snow depths were spatially distributed across the watershed through kriging interpolation methods which provide unbiased estimates that have minimum variances. Snow densities were spatially modeled through regression analysis. Combining the modeled depth and density with snow-covered area (SCA) produced an estimate of the spatial distribution of SWE. The kriged estimates of snow depth explained 37-68% of the observed variance in the measured depths. Steep slopes, variably strong winds, and complex energy balance in the watershed contribute to a large degree of heterogeneity in snow depth. JF - 66th Annual Western Snow Conference T3 - Proceedings of the 66th Annual Western Snow Conference PB - Western Snow Conference CY - Snowbird, Utah UR - sites/westernsnowconference.org/PDFs/1998Balk.pdf ER - TY - Generic T1 - Using GIS to establish relationships between environmental variables and snowdepths in Green Lakes Valley, Colorado, for use in SWE estimations and forecasting T2 - 66th Annual Western Snow Conference Y1 - 1998 A1 - Brown, S.M. A1 - Williams, M.K. KW - Forecasting, GIS, Niwot Ridge AB - Geographic Infonnation Systems (GIS) may be useful in forecasting the quantity ofwater stored in alpine snowpacks because relationships may be established between environmental characteristics and seasonal snowdepth patterns for watersheds of interest. A snow survey perfonned in May of 1997 for the 224-ha Green Lake 4 Watershed of the Colorado Front Range involved intensive sampling (n = 194) of snowdepth and snow density measurements around the basin. These field data, in conjunction with snow covered area, DEM and landcover data from the Niwot Ridge LTER Spatial Database, were used to investigate 1) the relationship of snowdepth to landcover, 2) the relationship of snowdepth to slope, and 3) the relationship of snowdepth to aspect. JF - 66th Annual Western Snow Conference T3 - Proceedings of the 66th Annual Western Snow Conference PB - Western Snow Conference CY - Snowbird, Utah UR - sites/westernsnowconference.org/PDFs/1998Brown.pdf ER - TY - Generic T1 - The UtahMesonet: Monitoring weather conditions over the intermountain west T2 - 66th Annual Western Snow Conference Y1 - 1998 A1 - Horel, J. A1 - Slemmer, J. A1 - McDonald, B. A1 - Dunn, L. A1 - Zaff, D. KW - SNOTEL, Weather network, Wind data AB - The Utah Mesonet has been under development during the past several years. The Mesonet has been designed tohelp forecasters in the Intermountain West obtain current weather conditions in a timely fashion. All available surface reports from manned and automated stations are collected, archived, and displayed at 15-minute intervals. While attention is focussed on meteorological parameters such as temperature and wind, precipitation information is also obtained from sensors installed by the National Weather Service near the Wasatch Mountains as well as information from Snow Telemetry (SNOTEL) sites and data collected by the Colorado River Basin Forecast Center.Operational and experimental forecasts of precipitation during January-May 1997 are evaluated over the western United States. The sensitivity of model forecast skill as a function of model horizontal resolution is assessed. Models that resolve the underlying terrain in greater detail (such as the 10 kIn and 29 kIn versions of the Eta model developed at the National Centers for Environmental Prediction) provide better forecasts of orographic precipitation during winter. JF - 66th Annual Western Snow Conference T3 - Proceedings of the 66th Annual Western Snow Conference PB - Western Snow Conference CY - Snowbird, Utah UR - sites/westernsnowconference.org/PDFs/1998Horel.pdf ER - TY - Generic T1 - Use of geology in NWSRFS calibrations; Nisqually River, Mt. Ranier, Washington T2 - 64th Annual Western Snow Conference Y1 - 1996 A1 - Martin, K. KW - Models, NWSRFS, Soil Moisture AB - Subsurface geology, rock types, and glacial processes greatly influence hydrogeologic processes. Good geologic understanding can create better insights for the initial estimation and subsequent adjustment of parametersof the Sacramento Soil Moisture Accounting (SAC-SMA) and SNOW-17 models of the National Weather Service's River Forecast System (NWSRFS). Geologic information is readily available from the Roadside Geology series or US Geological Survey Geologic maps.The Nisqually River near National, Washington, is divided into four areas in NWSRFS. The Lower area, filled by glaciofluvial sediments, displays a subdued hydrologic response. This geological information translates as deep SAC-SMA tension-water and free-water parameter boxes which indicate high porosity and permeability, plus significant baseflow; low SAC-SMA REXP and ZPERC values suggest rapid percolation; and low SAC-SMA UZK values mean slow recessions. The Middle and Upper areas feature massive volcanic flows which are hydrologically flashy.The Glacial area shows a glacial peak flow by August. SNOW-17 model parameters show a glacier covering 40% of a volcanic terrain. The NWSRFS Water Balance operation incorporates mass balance analyses (eg., Accumulation Area Ratio) showing glacial growth or recession. The Nisqually glacier shows a 3% decline. JF - 64th Annual Western Snow Conference T3 - Proceedings of the 64th Annual Western Snow Conference PB - Western Snow Conference CY - Bend, Oregon UR - sites/westernsnowconference.org/PDFs/1996Martin.pdf ER - TY - Generic T1 - Updating seasonal snowmelt estimates using snowcourse measurements T2 - 63rd Annual Western Snow Conference Y1 - 1995 A1 - Assaf, H. A1 - Loukas, A. A1 - Quick, M. KW - Snow courses, Streamflow forecasting AB - In mountainous watersheds, like those of British Columbia and northern Pakistan, rivers are mainly fed by snowmelt from winter-accumulated snowpack and glaciers. For a safe and optimal operation of reservoirs fed by these watersheds, it is important to obtain reliable estimates of the volume and time distribution of seasonal snowmelt.An iterative procedure has been developed to utilize snow course measurements to update estimates of snowfall contribution to the watershed. Consequently snowpack volume available for melting is modified and seasonal forecasts are adjusted accordingly.The updating scheme has been applied to the snowpack measured at Mount Fidelity in the Upper Columbia River Basin in British Columbia. The results showed great improvements is streamflow forecasts, particularly during the critical melting season. JF - 63rd Annual Western Snow Conference T3 - Proceedings of the 63rd Annual Western Snow Conference PB - Western Snow Conference CY - Sparks, Nevada UR - sites/westernsnowconference.org/PDFs/1995Assaf.pdf ER - TY - Generic T1 - Using the WRNSHYD procedure to estimate long-term cummulative effects of aspen clearcutting on water yield in Alberta T2 - 62nd Annual Western Snow Conference Y1 - 1994 A1 - Swanson, R.H. KW - Clearcutting, Cumulative effects, Evapotranspiration, Model, Simulation, Snow transport, WRENSS AB - Snow accumulation, evaporative loss of snow, summer evapotranspiration and ultimately water yield are affected by clearcut harvesting. As harvesting progresses through time, regrowth occurs that limits the effect that wind can have on the transport and redeposition of snow from clearcut areas. Basal area also increases, altering the effect on evapotranspiration. Regrowth can be estimated and input into the hydrology portion of the USFS Water Resources Evaluation of Non-point Silvicultural Sources (WRENSS) procedure to obtain an estimate of the cumulative effects of harvest through time.The hydrology section of the WRENSS procedure indicates that if the height of regrowth is greater than the depth of the snowpack, wind driven snow transport and loss in transport are nil. This generally occurs by the second year after clearcutting in the boreal forest of Canada where aspen regrowth occurs rapidly from root sprouts after clearcutting. Basal area increases to about 30 sq m/ha in the first 30 years after harvest and by year 20 is sufficiently high so that the estimated increases in evapotranspiration are essentially nil. The net effect in WRENSS of the combined effects of clearcutting on snow accumulation, snow transport, loss in transport and evapotranspiration is zero for any single clearcut in aspen forest of the region by 25 years after harvest.The cumulative effects of periodic harvests within a 546 km² watershed over various time intervals were estimated to determine possible harvesting regimes in order to maintain the annual water yield increase below 15% at the first significant user, a criterion established by Alberta Environment to minimize flooding impacts on downstream residents and water users. Three harvesting scenarios were simulated: 1) continuous harvest of 400,000 cu m/yr until all of the merchantable timber is removed (approximately 15 years), 2) continuous harvest at 200,000 cu m/yr for 30 years and 3) continuous harvest at 100,000 cu m/yr over a 60 year rotation. The first scenario is the only one that resulted in a maximum increase (21%) in water yield greater than 15% at the boundary of the watershed. The other two scenarios resulted in maximum water yield increases of 11% and 6% respectively. JF - 62nd Annual Western Snow Conference T3 - Proceedings of the 62nd Annual Western Snow Conference PB - Western Snow Conference CY - Sante Fe, New Mexico UR - sites/westernsnowconference.org/PDFs/1994Swanson.pdf ER - TY - Generic T1 - The use of fractual geometry in modelling intercepted snow accumulation and sublimation T2 - 61st Annual Western Snow Conference Y1 - 1993 A1 - Pomeroy, J. A1 - Schmidt, R.A. KW - Fractuals, Interception, Modelling, Sublimation AB - In the boreal forest, interception of snow can store 60% of cumulative snowfall in mid-winter and sublimation of this snow can return over 30% of annual snowfall to the atmosphere as water vapour. A sublimation algorithm for a single ice sphere and an ‘exposure coefficient’ which accounts for the difference in surface area to mass ratios between intercepted snow and the ice sphere permit calculation of the sublimation rate in coniferous canopies. Fractal geometry provides a tool to calculate this exposure coefficient from digitised photographs of snowcovered canopies. Intercepted snow is fractal and the irregularity of its shape depends on locaton in the canopy and age of the snow. The fractal shape of intercepted snow permits a relationship between snowcovered area in canopy photographs and interception load. The analysis shows the feasibility of a physically-based model of intercepted snow accumulation and sublimation that uses standard meteorological measurements and digitised photographs of the canopy. JF - 61st Annual Western Snow Conference T3 - Proceedings of the 61st Annual Western Snow Conference PB - Western Snow Conference CY - Quebec City, Quebec UR - sites/westernsnowconference.org/PDFs/1993Pomeroy.pdf ER - TY - Generic T1 - Use of state-of-the-art systems for optimum water management T2 - 58th Annual Western Snow Conference Y1 - 1990 A1 - Horciza, E. KW - Equipment, Extremes, Systems, Water Management, Water supply AB - Moist Pacific air masses and effects from the Pacific 'high' can create a wide range of weather conditions in California. As a result, the annual runoff in California has ranged from 18 to 167 million dekameters during recent years. Such variability of the water supply makes it difficult for water agencies and public utilities to manage optimally their water resources.Pacific Gas and Electric Company, which owns and operates fifteen hydroelectric developments in northern and central California, uses many state-of-the-art methods and equipment to make the best possible use of the available water supply.The systems PG&E uses to manage its water resources and to comply with license and contract requirements include supervisory control and data acquisition systems, dam, canal, and penstock safety monitoring systems, power plant efficiency monitoring systems, the Hydroelectric Systems Scheduling Model, and Hydro-Thermal Optimization Model. JF - 58th Annual Western Snow Conference T3 - Proceedings of the 58th Annual Western Snow Conference PB - Western Snow Conference CY - Sacramento, California UR - sites/westernsnowconference.org/PDFs/1990Horciza.pdf ER - TY - Generic T1 - Using ratios of runoff to snow water content and to projected rainfall to-come, as a method of narrowing the water supply forecast range T2 - 58th Annual Western Snow Conference Y1 - 1990 A1 - Stein, R.E. KW - Ratio, Water supply forecasting AB - The need to provide accurate, weekly water supply forecasts when snow surveys are conducted only monthly, and the need to be continuously prepared if dry conditions persisted during this last drought, led to development of a forecasting technique that uses a combination of snow survey information, and the historical relationship between runoff and snow water content and rainfall. The observed decrease in the historical ratio of runoff to precipitation as seasonal rainfall declined, was included in the forecasting technique.Initially, runoff amounts (water years) for all available years of record were compared with seasonal rainfall (rainfall years) to develop runoff to rainfall ratios, which provided the general change in the ratio from wet to dry years. JF - 58th Annual Western Snow Conference T3 - Proceedings of the 58th Annual Western Snow Conference PB - Western Snow Conference CY - Sacramento, California UR - sites/westernsnowconference.org/PDFs/1990Stein.pdf ER - TY - Generic T1 - Use of new SSAR model automatic adjustment updating procedure T2 - 56th Annual Western Snow Conference Y1 - 1988 A1 - Orwig, C.E. A1 - Davis, E.M. KW - Real-time Forecasting, Snowmelt modeling AB - Real-time forecast operations with the SSARR model have always required that the model have a routine to automatically adjust model streamflows to abserved conditions. Recently, efforts by the Corps of Engineers and the National Weather Service have led to an improved method for automatic model adjustment. Testing of the new procedure on both a rainfall runoff area and on a snowmelt area demosntrate that the new method shows promise for application in real-time forecasting efforts. JF - 56th Annual Western Snow Conference T3 - Proceedings of the 56th Annual Western Snow Conference PB - Western Snow Conference CY - Kalispell, Montana UR - sites/westernsnowconference.org/PDFs/1988Orwig.pdf ER - TY - Generic T1 - The use of data logging systems in snow hydrology T2 - 52nd Annual Western Snow Conference Y1 - 1984 A1 - Cundy, T.W. KW - Forested versus open, Meteorological data, Snowmelt modeling AB - Meteorological data were collected in an open and forested site for one month. Air temperature, relative humidity, windspeed and the solar radiation were recorded over 30 minute, 30 minute, 10 minute and 10 minute intervals, respectively. Daily averages were calculated by averaging the data recorded over these shorter time intervals. Regression analyses indicated that the relationships between the open and forested sites for these variables were independent of the averaging intervals used here. The implications of this result are discussed. JF - 52nd Annual Western Snow Conference T3 - Proceedings of the 52nd Annual Western Snow Conference PB - Western Snow Conference CY - Sun Valley, Idaho UR - sites/westernsnowconference.org/PDFs/1984Cundy.pdf ER - TY - Generic T1 - Undisturbed measurement of the energy and mass balance of a deep alpine snowcover T2 - 48th Annual Western Snow Conference Y1 - 1980 A1 - Davis, R. A1 - Marks, D. KW - Micrometeorological Instrumentation, Snow hydrology AB - The testing and development of energy balance snowmelt models requires the undisturbed measurement of various energy exchange components, snow mass balance, and snow and soil properties. A micrometeorological station providing such measurements has been established in cooperation with the U.S.F.S. at 2930 m on Mammoth Mtn. in the southern Sierra Nevada. This site has an average winter snow depth of around 3 m, and can be as deep as 8 m. Radiometers measure incoming and reflected solar radiation in two wavelength bands, and incoming and emmitted thermal radiation in one wavelength band. Surface fluxes of latent and sensible heat are determined with a very accurate dew point sensor utilizing the `condensation mirror approach', two anemometers, and the measurement of emitted thermal radiation. Snow-soil thermal interaction is estimated using thermistor arrays at fixed spacing. Snow water content and average density are obtained from a snow pillow and depth stake. Dynamic measurement of snow settlement, and temperature profiles is done using a sliding platter device similar to that described by Swanson (1968) which allow a depth location with temperature. JF - 48th Annual Western Snow Conference T3 - Proceedings of the 48th Annual Western Snow Conference PB - Western Snow Conference CY - Laramie, Wyoming UR - sites/westernsnowconference.org/PDFs/1980Davis.pdf ER - TY - Generic T1 - Upper air data as a parameter in estimating snowmelt runoff T2 - 43rd Annual Western Snow Conference Y1 - 1975 A1 - Hannaford, J.F. A1 - Howard, C.H. KW - Models - hydrologic AB - Hydrologic models have been designed to simulate mean daily runoff on the Kings River and San Jaoquin River. These models utilize certain parameters indicating the condition of the watershed such as snow, precipitation, and daily temperatures throughout the snowmelt period. It might be desirable to determine what runoff condition would prevail if temperatures were higher or lower than average. An estimated surface temperature at the 7,000 foot elevation has been utilized. This method produces an index which is useful in estimating the effects of air temperatures, radiation and perhaps factors in priming and melting snowpacks. JF - 43rd Annual Western Snow Conference T3 - Proceedings of the 43rd Annual Western Snow Conference PB - Western Snow Conference CY - Coronado, California UR - sites/westernsnowconference.org/PDFs/1975Hannaford.pdf ER - TY - Generic T1 - U. S. Forest Service claims - between the snowpack and downstream water interests T2 - 41st Annual Western Snow Conference Y1 - 1973 A1 - Cooley, J.R. A1 - Mulvaney, R.J. KW - Comprehensive water management, Water regulation, Water rights AB - A discussion of control and water rights in the United States. Deals primarily with the State of Colorado methods of adjudication of water rights including claims by the United States. Conflicts under state law with rights of others to divert water - a right that Colorado Constitution says will never be denied. Indicates need for comprehensive water management due to population growth and environmental concerns. JF - 41st Annual Western Snow Conference T3 - Proceedings of the 41st Annual Western Snow Conference PB - Western Snow Conference CY - Grand Junction, Colorado UR - sites/westernsnowconference.org/PDFs/1973Cooley.pdf ER - TY - Generic T1 - The use of snow fences for shielding precipitation gages T2 - 39th Annual Western Snow Conference Y1 - 1971 A1 - Rechard, P.A. A1 - Larson, L.W. KW - Precipitation gage, Snow drifting, Snow shield, Statistical analysis AB - The development and operation of a research project developed by the Wyoming Water Resources Research Institute under contract with the National Oceanic and Atmospheric Administration is described. Preliminary information on precipitation data, statistical analysis, snow drift profiles, and wind characteristics are presented. The data shows that there is a distinct possibility of shielding precipitation gages from the adverse effects of wind by using artificial barriers (snow fences). JF - 39th Annual Western Snow Conference T3 - Proceedings of the 39th Annual Western Snow Conference PB - Western Snow Conference CY - Billings, Montana UR - sites/westernsnowconference.org/PDFs/1971Rechard.pdf ER - TY - Generic T1 - Using all available hydrologic data T2 - 38th Annual Western Snow Conference Y1 - 1970 A1 - Russell, S.O. A1 - Obedkoff, W. KW - Basin characteristics, Flow analysis, Hydrology AB - An approach to the use of both meteorological and streamflow data has been developed by S.J. Solomon et al, and applied in Labrador. In this method, a river basin is divided into a number of squares, physiographic parameters are determined for each square, meteorological data are correlated with these parameters and from the resulting equation estimates are made of precipitation, evaporation and runoff for each square. Accumulated runoff is compared with measured runoff.This paper describes an attempt to apply the method to a mountainous area in the interior of British Columbia to determine the areal variation in runoff and also to extend the method by using snow course data as well as meteorological and stream gauge data. The results are promising and the technique has important implications for data network design. JF - 38th Annual Western Snow Conference T3 - Proceedings of the 38th Annual Western Snow Conference PB - Western Snow Conference CY - Victoria, British Columbia UR - sites/westernsnowconference.org/PDFs/1970Russell.pdf ER - TY - Generic T1 - A universal surface precipitation gage T2 - 36th Annual Western Snow Conference Y1 - 1968 A1 - Cox, L.M. A1 - Hamon, W.R. KW - Precipitation gage, Snow water content, Snow water equivalent, Storage gage AB - A universal surface precipitation gage has been developed that measures total precipitation and records the precipitation remaining in storage as snow. A 5-foot-diameter platform made of light weight concrete, is supported by a liquid-filled 100-foot coil of butyl tubing. An opening in the center of the platform allows for the collection of atmospheric melt, rain percolate and melt, or a combination of these, and rainfall. A mechanical dual-pen recorder continuously records the rate of water collected in an underground tank and the water equivalent of snow on the platform. This recording system satisfies the long-standing need for surface measurement of total precipitation, snowmelt rates, and snow water equivalent required in hydrologic research and water yield and flood forecasts. JF - 36th Annual Western Snow Conference T3 - Proceedings of the 36th Annual Western Snow Conference PB - Western Snow Conference CY - Lake Tahoe, Nevada UR - sites/westernsnowconference.org/PDFs/1968Cox.pdf ER - TY - Generic T1 - Use of snow surveys to forecast inflow to Snake River betwween Milner and King Hill, Idaho T2 - 35th Annual Western Snow Conference Y1 - 1967 A1 - Thomas, C.A. KW - Return flow, Water supply forecasting AB - Snow surveys are widely used to forecast flows in streams to which snowmelt is directly tributary, and to estimate the magnitude and duration of water supplies fed by such streams. A proposed method is described and results discussed in the text and illustrated by plotted data on graphs. The main problem is to account for the large amount of return irrigation water and the amount of water flowing from huge springs along the river banks in this reach of the river. This flow amounts to approximately 7,500 cfs, during a good portion of the year, and especially during the snowmelt season. JF - 35th Annual Western Snow Conference T3 - Proceedings of the 35th Annual Western Snow Conference PB - Western Snow Conference CY - Boise, Idaho UR - sites/westernsnowconference.org/PDFs/1967Thomas.pdf ER - TY - Generic T1 - The U.S. Program for the IHD, with Special Reference to Snow and Ice Y1 - 1966 A1 - Meier, M.F. PB - Western Snow Conference CY - Seattle, Washington UR - sites/westernsnowconference.org/PDFs/1966Meier.pdf ER - TY - Generic T1 - Use of Lake Roosevelt storage to lower river temperatures T2 - 31st Annual Western Snow Conference Y1 - 1963 A1 - Kramer, H.A. A1 - Corley, J.P. KW - Water temperatures AB - A discussion of procedures used to lower the temperature of the water in the Columbia River below Grand Coulee Dam by releasing water from lower, cooler levels of the reservoir. This process improves the economics of using the cool water for downstream plants and also improves the fish habitat during the warm months of the year. Graphical analysis of thermoclines of the reservoir waters above the dam makes possible this operation. JF - 31st Annual Western Snow Conference T3 - Proceedings of the 31st Annual Western Snow Conference PB - Western Snow Conference CY - Yosemite National Park, California UR - sites/westernsnowconference.org/PDFs/1963Kramer.pdf ER - TY - Generic T1 - Use of snow surveys by Denver Water Board T2 - 30th Annual Western Snow Conference Y1 - 1962 A1 - Fischer, R.W. KW - Municipal water supply, Networks AB - A historical review of the Denver city water system from the beginning in 1872 with steady growth and transcontinental diversion from west to east through the Moffit Tunnel in 1936. The need for additional reservoir storage has become evident. In order to better manage the storage problem and diversions, an addition is being made to the present snow survey course network to meet the demands for more accurate streamflow forecasting. Proposed locations of courses are shown on the accompanying map of the project. JF - 30th Annual Western Snow Conference T3 - Proceedings of the 30th Annual Western Snow Conference PB - Western Snow Conference CY - Cheyenne, Wyoming UR - sites/westernsnowconference.org/PDFs/1962Fischer.pdf ER - TY - Generic T1 - Use of snow survey reports in predicting snow runoff T2 - 28th Annual Western Snow Conference Y1 - 1960 A1 - Ball, H. KW - Reservoit regulation, Water supply forecasting AB - A discussion of meteorological occurrences of flood and drought over the Rio Grande river basin is presented. It is pointed out that for the lack of sufficient data to prove any long time or even short cyclic occurrences of weather pattern, the prediction lacks a solid mathematical basis. Historical data from archaeological findings are quoted. The beneficial use of short term (15 year) averages of snow survey, temperature, wind movement, and soil moisture data produce a good forecast of streamflow during the melt season. The economical value of advance information for regulating irrigation reservoirs is pointed out as a distinct value to both power and irrigation interests. JF - 28th Annual Western Snow Conference T3 - Proceedings of the 28th Annual Western Snow Conference PB - Western Snow Conference CY - Santa Fe, New Mexico UR - sites/westernsnowconference.org/PDFs/1960Ball.pdf ER - TY - Generic T1 - Use of the electronic computer for streamflow analysis T2 - 28th Annual Western Snow Conference Y1 - 1960 A1 - Johnson, L.F. KW - Electronic computer, Snow cover, Statistics, Water supply forecasting AB - A description of the processes used on the electronic computer for deriving multiple regression formulas using the many independent variables required in snow water supply forecasting is presented. The advantage of obtaining statistical relations between as many as 33 variables and streamflow figures within 15 minutes is shown. The detail results and procedures for developing a multiple regression formula for the Madison River at West Yellowstone, Montana with explanation of results, are given. Reasons for the 4 different forecast periods, together with peak flow and number of days to exceed critical flows are described. Four tables are included to show the results of the statistical criteria and formulas used. JF - 28th Annual Western Snow Conference T3 - Proceedings of the 28th Annual Western Snow Conference PB - Western Snow Conference CY - Santa Fe, New Mexico UR - sites/westernsnowconference.org/PDFs/1960Johnson.pdf ER - TY - Generic T1 - Use of snow-melt forecasting by the Corps of Engineers for flood control operations of the Rio Grande River T2 - 28th Annual Western Snow Conference Y1 - 1960 A1 - Martin, J.T. KW - Flood control prediction, Water supply forecasting AB - The Federal law under which the U.S. Corps of army Engineers is authorized to enter into the construction, operation and regulation of flood control structures such as dams, levees, and river channel improvements of future streamflow management, is outlined. The three operational divisions of the Rio Grande River above El Paso, Texas are delineated on a map and the plan of regulation is described. The absolute need for accurate water supply forecasts from snow survey data, precipitation and soil moisture data is shown. Case histories and operational techniques are described showing further need for reliable forecasts and the close cooperation of all agencies involved. JF - 28th Annual Western Snow Conference T3 - Proceedings of the 28th Annual Western Snow Conference PB - Western Snow Conference CY - Santa Fe, New Mexico UR - sites/westernsnowconference.org/PDFs/1960Martin.pdf ER - TY - Generic T1 - Use of soil moisture resistance units in water supply forecasting T2 - 27th Annual Western Snow Conference Y1 - 1959 A1 - Stockwell, H.J. KW - Soil moisture, Water supply forecasting AB - Soil moisture measuring units are used to sample the soil moisture condition under the snowpack. The data derived is used as a correction factor in preparing water supply forecasts when using water content snow survey data. Field installation procedures are discussed as to location of measurement site and placement of units at regular intervals in the soil as a stack of units. A conversion chart of ohms resistance to percent soil moisture in the several horizons of soil are illustrated. The existing network of soil moisture stations in Colorado and New Mexico river basins are mentioned in connection with their use in water supply forecasting. JF - 27th Annual Western Snow Conference T3 - Proceedings of the 27th Annual Western Snow Conference PB - Western Snow Conference CY - Reno, Nevada UR - sites/westernsnowconference.org/PDFs/1959Stockwell.pdf ER - TY - Generic T1 - Use of snow survey data by soil conservation districts T2 - 26th Annual Western Snow Conference Y1 - 1958 A1 - Fredericksen, D.C. KW - Economics, Farm irrigation, Water management AB - The farmer water-users are taking an active part in the Soil Conservation Service Districts in the Western States. A large number depend on snowmelt water for irrigation, reservoir storage, and water management. They are taking a keen interest in water supply forecast committee meetings and forecast bulletins issued primarily for localized use. These local bulletins and committee meetings show a marked economic impact on the farm crop planning, particularly when there is a short supply of water. Savings in farm operation can amount to as much as $378,850 in one year in one Conservation District by, (1) saving on land preparation, (2) selection of crops that use small amounts of water, and (3) good water management. Although this case may be an ideal situation, other Districts can show a great savings by proper farm management and water conservation through the use of the localized forecast bulletin data. JF - 26th Annual Western Snow Conference T3 - Proceedings of the 26th Annual Western Snow Conference PB - Western Snow Conference CY - Bozeman, Montana UR - sites/westernsnowconference.org/PDFs/1958Fredericksen.pdf ER - TY - Generic T1 - The use of Fourier series in streamflow forecasting T2 - 25th Annual Western Snow Conference Y1 - 1957 A1 - Milligan, C.H. KW - Forecast procedures, Fourier series AB - A new approach to streamflow forecasting is described clearly but briefly in using the Fourier Series as a forecasting tool. A complete array of data is tabulated for the Logan River near Logan, Utah, using four (4) independent variables:(1) Daily and average monthly temperatures at valley stations(2) Daily and monthly precipitation at valley stations(3) Daily and monthly streamflow(4) April 1 snow survey data at 7 mountain stations in the Logan River drainage.Fourier Series coefficients are developed for these variables and applied to the 1956 field data. The resulting forecast for that year was only in error by 9% of the observed runoff.In discussion Mr. George R. Hamburg and Mr. H. Boyd Phillips pointed out the advantage of this seldom used forecast procedure for working with inflow to reservoirs. JF - 25th Annual Western Snow Conference T3 - Proceedings of the 25th Annual Western Snow Conference PB - Western Snow Conference CY - Santa Barbara, California UR - sites/westernsnowconference.org/PDFs/1957Milligan.pdf ER - TY - Generic T1 - Use of electrical soil-moisture units in mountain soils T2 - 23rd Annual Western Snow Conference Y1 - 1955 A1 - Horton, J.S. KW - Colman units, Soil moisture measurements AB - A procedure for measuring soil moisture at several depths in a mountain soil mantle using fiberglass, monel metal units (Colman Units) is presented. These units have a thermister (temperature element) encased in the monel metal case. Three wire leads are brought to the surface through a pipe to prevent rodent damage. The meter is an alternating current design circuit to measure impedance In milli-amps, thus averting a direct resistance reading that would be contaminated by soil salts or acids. The milli-amps readings are converted to Ohms by a calibration chart furnished with each meter. The process of calibrating the units to soil moisture by field and laboratory procedures is discussed. Calibration curves are exhibited. A discussion of results is included in the text of the paper. JF - 23rd Annual Western Snow Conference T3 - Proceedings of the 23rd Annual Western Snow Conference PB - Western Snow Conference CY - Portland, Oregon UR - sites/westernsnowconference.org/PDFs/1955Horton.pdf ER - TY - Generic T1 - Use of aircraft in snow surveying T2 - 22nd Annual Western Snow Conference Y1 - 1954 A1 - Codd, A.R. A1 - Nelson, M.W. KW - Aircraft use in snow surveys, Snow survey transportation AB - The advantages and disadvantages of using airplanes in snow surveying are described and comparative cost data for overland surveying are tabulated. Airplanes are successfully employed on several snow course at the present time. The chief obstacle to their use is possible adverse weather conditions at the time the survey is scheduled, and the possibility of taking off from a dry airport and landing on a snow covered pasture near the snow course. Comparison indicates that the cost of measuring courses by air are more consistent, but other aspects of cost are difficult to compare. A few general specifications for snow landings at elevations from 5000-10,000 feet are given. JF - 22nd Annual Western Snow Conference T3 - Proceedings of the 22nd Annual Western Snow Conference PB - Western Snow Conference CY - Salt Lake City, Utah ER - TY - Generic T1 - Use of melt-season snow surveys T2 - 22nd Annual Western Snow Conference Y1 - 1954 A1 - Koelzer, V.A. KW - Runoff, Snowmelt, Statistical analysis AB - A method of interpreting results of snow surveys after the start of snow melt is given, and use of the procedure is illustrated for a section of the North Platte River basin. This involves relating the amount of snowmelt to the amount of snow measured at given dates after the melting season commences. Regular melt season surveys are recommended for areas with present and planned substantial control structures.In discussion Mr. Homer J. Stockwell points out the need for snow survey data during the melt season. He also points out the possibility of including soil moisture data during the late season forecasts, particularly on streams where substantial control structures are planned. JF - 22nd Annual Western Snow Conference T3 - Proceedings of the 22nd Annual Western Snow Conference PB - Western Snow Conference CY - Salt Lake City, Utah ER - TY - Generic T1 - U. S. Weather Bureau snow cover observation program T2 - 21st Annual Western Snow Conference Y1 - 1953 A1 - Butson, K.D. KW - Photographic analysis of snowcover, Snowcover distribution AB - Photographic observational techniques for snow surveying the Columbia Basin, under study by the weather Bureau, are described briefly. Twelve stations for obtaining photographs by cooperative observers were in operation in 1952 and 1953. No conclusive results are given, but comparison of photographs obtained in 1952 with the daily streamflow suggest favorable results. JF - 21st Annual Western Snow Conference T3 - Proceedings of the 21st Annual Western Snow Conference PB - Western Snow Conference CY - Boise, Idaho ER - TY - Generic T1 - The use of aerial photographs of snow depth markers in water supply forecasting T2 - 21st Annual Western Snow Conference Y1 - 1953 A1 - Henderson, T.J. KW - Aerial markers, Water supply forecasting, Weather modification methods AB - Snow depth markers are placed at inaccessible locations to obtain snow depth by aerial photographs and visual observations. This data is related information from an accessible snow course, at similar elevation, where depth, water content and density are available. The density is then used to obtain the water content at the MARKER station. Many marker stations can be read in a single flight and in a few hours. A minimum of cost and time is expended to obtain much more data. This information is used in water supply forecasting and in weather modification evaluation. Photographs depict the style of the markers and locations being used. Graphs indicate the comparison of both types of data from the same location. JF - 21st Annual Western Snow Conference T3 - Proceedings of the 21st Annual Western Snow Conference PB - Western Snow Conference CY - Boise, Idaho ER - TY - Generic T1 - Use of base flow in forecasting runoff during the non-flood season T2 - 21st Annual Western Snow Conference Y1 - 1953 A1 - McDonald, C.C. KW - Base flow, Water supply forecasting AB - A study is presented of streamflow for the period July through September for the Salmon river at Whitebird, Idaho as related to 'Base Flow' on July first. 'Base Flow' is considered to be the flow of a river after the snowmelt flood has drained from the soil and ground water aquifers and the recession graph has started to flatten off. Base flow on July 1 and precipitation during the period account for 97% of the variance in runoff. It is possible to forecast the total runoff from July through September within limits of error normally acceptable in water supply forecasting by means of base flow alone. The approach to each river would, of course, be different, but the theory holds. Relationships are shown graphically with probability and frequency curves being exhibited together with tabulated data and formula development. JF - 21st Annual Western Snow Conference T3 - Proceedings of the 21st Annual Western Snow Conference PB - Western Snow Conference CY - Boise, Idaho ER - TY - Generic T1 - The use of precipitation and snow survey data in water supply forecasting T2 - 21st Annual Western Snow Conference Y1 - 1953 A1 - Polos, A.J. KW - Water supply forecasting AB - The use of precipitation measurements and snow survey data singly and in combinations for forecasting is discussed and applied to the North Fork Clearwater River in Idaho. An average error of 8.7% was obtained using precipitation data alone, and 4.6% when combined with snow survey data. Forecasts issued by the Weather Bureau in January, February and March will use only precipitation data but April and May forecasts will also utilize snow survey data where applicable.In discussion Mr. Clarence Pederson indicates his approval of the combination of variables in the formula. However, he warns against using a precipitation period that extends beyond the date of the forecast. Using estimated or average figures invariably leads to trouble. Also reliable accuracy checks cannot be made by inserting the values of the variables used in developing the formula. If every 3rd or 5th data is omitted, and then a reliability check is made using these omitted, the check will be much more significant. JF - 21st Annual Western Snow Conference T3 - Proceedings of the 21st Annual Western Snow Conference PB - Western Snow Conference CY - Boise, Idaho ER - TY - Generic T1 - Use of snow surveys in evaluating cloud-seeding operations T2 - 20th Annual Western Snow Conference Y1 - 1952 A1 - Beaumont, R.T. A1 - Work, R.A. A1 - Frost, W.T. A1 - Barton, M. KW - Weather modification evaluation AB - Methods using data from mountain snow survey courses to study the results of cloud seeding are presented. Cloud seeding, to increase the snowpack and produce more water for irrigation on watersheds of the Rogue River Valley, Oregon, occurred from November 1949 through March 1950, and from November 1950 through March 1951. The target area and the techniques used in cloud seeding are described. Snow course records maintained 9-19 years in the target area and in upwind surrounding areas were analyzed. Correlation coefficients were established and used to determine if the target area received proportionately more or less water equivalent as snow than the surrounding areas. Analysis shows that less water was stored in the snow in the target area during the 2-year period of cloud seeding than expected under natural conditions. Further studies are required to determine whether the relationships between snow courses and streamflow sere modified by seeding. JF - 20th Annual Western Snow Conference T3 - Proceedings of the 20th Annual Western Snow Conference PB - Western Snow Conference CY - Sacramento, California ER - TY - Generic T1 - The use of soot for snow removal purposes T2 - 20th Annual Western Snow Conference Y1 - 1952 A1 - Lang, W.A. KW - Snow removal from roads, Snowcover radiation, Solar radiation AB -

Eight test plots, 10x10 feet, covered with 10 inches of snow, were evenly spread with soot varying from 0-10 pounds per plot. Snow depth and water content were measured with a sampler at the center of each plot before applying the soot and again 4 hours later. The temperature ranged from 22 deg to 47 deg F during the experimental period. The greatest decrease in snow depth occurred in the plot covered with 1 pound of soot. The rate of decrease in snow was almost twice as great on the sooted spots than on clear plots. No significant difference in the decrease of water content was found. Lampblack was applied experimentally on the Kaiser Pass road on March 30, 1951, at the rate of 10 pounds per 100 square feet as a method of snow clearance in spring. The danger of spreading the soot too thickly and preventing melting is pointed out in the discussion.In discussion Dr. Robert W. Gerdel points out some interesting references on the subject of 'Unconventional Methods of Snow Removal'

JF - 20th Annual Western Snow Conference T3 - Proceedings of the 20th Annual Western Snow Conference PB - Western Snow Conference CY - Sacramento, California UR - sites/westernsnowconference.org/PDFs/1952Lang.pdf ER - TY - Generic T1 - Use of snow surveys in planning regulation of Columbia River floods T2 - 19th Annual Western Snow Conference Y1 - 1951 A1 - Work, R.A. A1 - Wilm, H.G. A1 - Nelson, M.W. KW - Statistical analysis, Water supply forecasting AB -

A practical method for making predictions of volumetric yield and flood discharges from snow is presented. Available data on the water stored in snow in the spring and during subsequent precipitation are obtained from 43 selected snow courses. The predictions are accompanied by estimates of error and probable limits within which the real yield or flood discharge is likely to fall, by statistical means. Two-thirds of the total error in predicting peak discharges is in the error associated with the relations of flood volume to snow water. Later season forecasts become progressively more precise. The effects of early season temperatures on peak discharge were indirectly evaluated by subtracting April volume from the estimated April-June volume, and relating flood discharges only to the remaining amount expected to flow during the last part of the 3-month period.Discussion by Clarence Pederson.

JF - 19th Annual Western Snow Conference T3 - Proceedings of the 19th Annual Western Snow Conference PB - Western Snow Conference CY - Victoria, British Columbia UR - sites/westernsnowconference.org/PDFs/1951WorkB.pdf ER - TY - Generic T1 - The use of double mass analysis in testing the consistency of climatological records T2 - 18th Annual Western Snow Conference Y1 - 1950 A1 - Diamond, M. KW - Precipitation analysis, Statistical analysis AB - Double mass analysis was used to investigate the consistency of precipitation records in the Upper Colorado River basin. Residual mass curves, represented as the accumulated excess or deficiency of rainfall in relation to time, are plotted for each precipitation station's record. A horizontal curve indicates no major change in the average precipitation. Stations with nearly horizontal residual mass curves are used in preparing a precipitation base pattern. The precipitation record of a single station is plotted accumulatively against the accumulated precipitation base pattern. A straight double mass curve indicates a consistent precipitation record. A bend in the curve indicates that the records have been affected by artificial changes in exposure or observer. The results of the study indicate that double mass technique is reliable when there is a high correlation between factors being compared. JF - 18th Annual Western Snow Conference T3 - Proceedings of the 18th Annual Western Snow Conference PB - Western Snow Conference CY - Boulder City, Nevada ER - TY - Generic T1 - The use of radioisotopes in research on snow and runoff T2 - 18th Annual Western Snow Conference Y1 - 1950 A1 - Gerdel, R.W. A1 - Mansfield, C.W. KW - Radioisotopes, Snow gage radioactive AB - Three radioactive snow gages were installed in the experimental area at the Central Sierra Snow Laboratory, during December 1949. A geiger tube was held by a 20-ft. Truss arm attached to a 50-ft. Pole. A lead shielded collimator imbedded in concrete beneath the truss arm held 2 units of radioactive Cobalt 60. Impulses of the geiger tube were amplified and transmitted over a 150-foot Cable to the recorder in the main laboratory. Largest sources of error were in variation of background impulses caused by cosmic rays. Four of 7 -- 5 minute counting periods each day gave accuracy within 2 to 5%. Water films of less than 0.01 inch to 55 inches can be measured by means of beta emissions from Strontium 90, and gamma rays from Cobalt 60. JF - 18th Annual Western Snow Conference T3 - Proceedings of the 18th Annual Western Snow Conference PB - Western Snow Conference CY - Boulder City, Nevada ER - TY - Generic T1 - Use of inflow forecasts in operation of Hoover Dam and Lake Mead for flood control T2 - 18th Annual Western Snow Conference Y1 - 1950 A1 - Lupton, F.R. KW - Reservoir regulation, Water supply forecasting AB - A review of regulations for operating Hoover Dam to meet legal requirements is presented. Economical operation of the dam in conjunction with power and irrigation requirements and maintaining discharge releases to inhibit flooding below the dam are described. Maximum flow downstream from the dam is limited to 40,000 cfs which adds another restriction in releasing large volumes of flood control water. Storage space above the dam also has its control height to guard against use of spillways, thus a loss of power. Inflow volumes to the reservoir are forecast for each month January through July. The forecast scheme is designed for temperature and evaporation factors. Various months use different weighting of factors to meet the conditions. Accuracy is high in the first few months but improves considerably in the later months. Tables and graphs illustrate procedure explained in the text.Discussion by Gerald B. Levin. JF - 18th Annual Western Snow Conference T3 - Proceedings of the 18th Annual Western Snow Conference PB - Western Snow Conference CY - Boulder City, Nevada ER - TY - Generic T1 - The use of snow surveys as an aid in flood control operation of reservoirs T2 - 12th Annual Western Interstate Snow Survey Conference Y1 - 1944 A1 - Christian, F.G. KW - Reservoir operation, Snowmelt hydrograph, Snowmelt runoff AB - The hypothetical operation of the proposed Pine Flat Dam on the Kings River, California as outlined by Paget is discussed. Several improvements in the technique of recognizing the start of the decline of runoff are suggested. Some of the methods permit recognition of the start of the decline within 5 days after the peak flow has occurred. (See also SIP 1908 - WSC 154-43)Discussion by L. Standish Hall presents a similar problem on the Mokelumne River in operating the Salt Springs and Pardee Dams. Operational graphs are presented and discussed. Further discussion is presented by R. K. Linsley, suggesting further methods of defining the snow melt hydrograph. JF - 12th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 12th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part I: CY - Berkeley, California ER - TY - Generic T1 - The Utah snow-mobile T2 - 12th Annual Western Interstate Snow Survey Conference Y1 - 1944 A1 - Clyde, G.D. KW - Oversnow vehicles, Utah snowmobile AB - The two basic principles making the Utah snowmobile successful for transportation over deep snowpack are the split track and the guide runner. The excessive weight of an ordinary tractor was overcome in the Utah Snow-mobile by mounting wide, light metal tracks on the rubber tires of an ordinary automobile. The tracks were wide to reduce the unit load on the snow surface. Snow packing between the tracks and the wheels was overcome by designing a split track with the wheels operating between the two segments of the track. This arrangement provided a self-cleaning device, preventing accumulation of snow between the tracks. Conventional steering tends to overturn the vehicle when one track was stopped. A movable runner, projected in front of the vehicle, operated on fixed swivel at the end of a frame which was rigidly fastened to the chassis. This runner was operated through a cable-chain mechanism fastened to the steering column of the vehicle. Photographs show the mechanical design and features of construction, also transportation over highways. Specifications and performance records are listed. JF - 12th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 12th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part I: CY - Berkeley, California ER - TY - Generic T1 - The use of snow-surveys as an aid in flood-control operation of reservoirs T2 - 11th Annual Western Interstate Snow Survey Conference Y1 - 1943 A1 - Paget, F.H. KW - Reservoir operation, Water supply forecasting AB -

Two types of floods occur on the Sierra tributaries of the San Joaquin River: winter floods from heavy rains, and late spring floods from melting snow. Snow survey data as of April 1 have provided a reasonable accurate forecast of total April through July streamflow. Snow melt floods can be predicted at least a week in advance from snow pack daily temperature data. A hypothetical operation of the proposed Pine Flat Dam is outlined on a policy adopted for the control of rain floods and water conservation aimed to have a full reservoir at the end of the snow runoff period.Tables and graphs illustrate the procedures.Discussions by James E. Jones and H.P. Boardman present agreement in the procedures described and present other factors for consideration for increased accuracy in reservoir operations.

JF - 11th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 11th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part III: CY - Corvallis, Oregon UR - /files/PDFs/1943Paget.pdf ER - TY - Generic T1 - The use of snow survey predictions in the operation of combined flood control and conservation reservoirs for regulation of snowmelt runoff T2 - 9th Annual Western Interstate Snow Survey Conference Y1 - 1941 A1 - Showman, A.C. KW - Reservoir regulation, Snowmelt runoff AB - Operation curves for Lake Tahoe (Calif.) are given and discussed. Construction of the curves is based on recorded snowmelt runoff, while their use is based on snow survey predictions of runoff. The hypothetical operation of Lake Tahoe for flood control and conservation, using snowmelt runoff versus release curves, is illustrated. As the season progresses and forecasts are more reliable the plan of operation can always be changed, probably up through late April or on the May first surveys. JF - 9th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 9th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part I-B: CY - Sacramento, California ER - TY - Generic T1 - Unit -- hydrograph T2 - 8th Annual Western Interstate Snow Survey Conference Y1 - 1940 A1 - Elliott, R.H. A1 - Sherman, L.K. KW - Flood control prediction, Snowmelt and runoff, Unit hydrograph AB - The application of the Unit-Hydrograph method of forecasting floods from rainfall is described. The same basic principals are suggested for designing a procedure of forecasting floods from snow covered portions of the river basin. The Unit-Hydrograph procedure involves searching the several snowmelt factors, to establish the unit of time with the unit of snowmelt resulting in a unit of runoff volume. These units are applied to the area of the basin involved. No sample calculation is presented. JF - 8th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 8th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part III-B: CY - Seattle, Washington UR - sites/westernsnowconference.org/PDFs/1940aElliott.pdf ER - TY - Generic T1 - The use of precipitation gage measurements in forecasting the inflow to Lake Mead T2 - 6th Annual Western Interstate Snow Survey Conference Y1 - 1938 A1 - Reedy, O.C. KW - Precipitation gages, Reservoir regulation, Water supply forecasting AB - With the completion of Boulder Dam and the filling of Lake Mead to maximum capacity, the problem of forecasting the inflow from the Colorado River became evident. Studies have been under way for several years gathering data and analysis work for developing a suitable formula to meet the complex problems involved in operating this huge multi-purpose project. Precipitation gage networks over the main and tributary basins had been intensified, snow survey courses established in the high elevations, evaporation and other pertinent meteorological data measuring stations been established in anticipation of the problem. Trial equations will have to be tested with actual practice to clear the deadwood and introduce new factors before a satisfactory solution is solved. JF - 6th Annual Western Interstate Snow Survey Conference T3 - Proceedings of the 6th Annual Western Interstate Snow Survey Conference PB - American Geophysical Union, Transactions, Part I: CY - Los Angeles, California ER -