Global Warming Effects on Snowfields and Water Supply Evaluated Using Snowmelt Runoff Modeling and Normalized Annual Data
Title | Global Warming Effects on Snowfields and Water Supply Evaluated Using Snowmelt Runoff Modeling and Normalized Annual Data |
Publication Type | Conference Proceedings |
Year of Conference | 2007 |
Authors | Rango, A., Martinec J., and Roberts R. |
Conference Name | 75th Annual Western Snow Conference |
Series Title | Proceedings of the 75th Annual Western Snow Conference |
Date Published | April 2007 |
Publisher | Western Snow Conference |
Conference Location | Kailua-Kona, HI |
Keywords | Global warming, snow cover, runoff, normalized year, Rio Grande |
Abstract | The effect of global warming on the snow cover and runoff in mountain basins can be evaluated by comparing present and future conditions modeled for a climate scenario. Rather than use a single historical year to represent today's climate, an improved method is presented which consists of deriving a so-called normalized year. In the Rio Grande basin near Del Norte, CO (3414 km2, 2432-4215 m a.s.l.) the effect of a hypothetical temperature increase of +4o C on the snow cover and runoff as experienced in hydrological year 1979 was evaluated. Because 1979 had relatively frequent temperatures below -4o C, snowmelt as well as conversion of snowfall to rainfall was limited during winter. The data set of 1979 was modified by applying the so-called normalized temperatures for the period 1957-1994. The predicted future snow conditions in the normalized year show a complete disappearance of snow in the lowest elevation zone (2432 - 2926 m a.s.l.) on April 1, due to an increased snowmelt in the winter. The resulting winter runoff which increased from 7.6% to 12.8% of the annual total, in 1979, now increases from 11.7% to 24.2% of the normalized annual total. |
URL | sites/westernsnowconference.org/PDFs/2007Rango.pdf |