Abstract

The hydrologic and geochemical response of rain-dominated versus snow-dominated catchments was investigated using multi-year measurements of precipitation, snow accumulation and melt, streamflow, soil moisture and meteorological variables. Research was carried out at the Kings River Experimental Watersheds (KREW), an integrated ecosystem project for long-term research on nested headwater streams in the Southern Sierra Nevada. KREW is also the site of the Southern Sierra Critical Zone Observatory (CZO). Snow at lower elevations exhibits multiple accumulation and melt cycles throughout the cold season, with soil moisture response similar across events and locations. Snow at higher elevations exhibits a single main melt period in spring, with streamflow lagging that at lower elevations. Soil moisture declines rapidly in the first week after snowmelt is completed, followed by a more-gradual decline thereafter. Local differences in the timing of snowmelt and soil drying between north versus south aspects and shaded versus open sites are both about one month, comparable to elevation differences in the average response. Interannual variability in timing is also similar. Evapotranspiration follows snowmelt and temperature patterns. Ionic concentrations are consistently higher in the rain-dominated sites. Two aspects of the elevational gradients offer lessons for how catchments will respond to climate warming, precipitation and snowmelt patterns. Soil moisture response to climate change is also indicated by aspect differences. Interannual differences provide indications of how geochemical fluxes in streamwater will respond to warming.

Citation

Bales, R.C., Hunsaker, C.T., Meadows, M., Kerkez, B., Glaser, S.D., Liu, F., (2009): Water and geochemical responses to seasonal changes across the rain-snow transition in the Southern Sierra Nevada (Invited) . Fall meeting, American Geophysical Union, December 2009. 90(52). Abstract B32A-06 .