DISTRIBUTION OF SOIL MOISTURE DYNAMICS IN A SMALL MOUNTAIN CATCHMENT

Soil moisture in semi-arid regions dominated by winter precipitation is recharged as a bulk influx during spring melt and dries down quickly during the ensuing months. This timing in combination with various spatially distributed landscape properties produces distinct spatial soil moisture patterns. The patterns must be recognized in a distributed manner to account for hydrologic processes of storage and redistribution. This research investigates the spatial correlation among distributed point measurements of soil moisture, and between soil moisture patterns and landscape properties such as topography, vegetation, and the spatial snowmelt patterns. We use temoral stability anaylisis to show preferred moisture regimes. Finally, we evaluate data using a combined snowmelt-soil water model to provide spatially and temporally continuous estimates of net recharge and evapotranspiration across the watershed. Recharge estimates are compared with measured streamflow measured at a weir at the base of the watershed. Reynolds Mountain East (RME) subcatchment in Southwestern Idaho is in an intermountain region exhibiting high variability in topography, vegetation, and snow distribution. RME encompasses an area of 0.6 km² with 19 neutron probe access tubes distributed throughout the catchment. Two years of soil moisture data were collected with supporting climate and snow distribution data. In addition, leaf area index was measured for different vegetation types. The soil water distribution is typically characterized by two regimes: the spring snow melt and summer dry down with a variable degree of recharge prior to snow fall in the during the fall. Distributed patterns of soil moisture have distinct correlation to snow and vegetation distribution.