On the spatiotemporal variability of soil moisture and evapotranspiration in a mountainous basin within the North American monsoon region

Abstract

In the North American monsoon (NAM) region, in-phase seasonality in precipitation and radiation should lead to corresponding changes in the catchment hydrologic response and its spatiotemporal variability. Nevertheless, relatively little is known on the catchment response in the NAM region because of the paucity of observations. Numerical watershed models, tested against field and remote sensing data, can aid in identifying catchment hydrologic patterns and the controls exerted by climate, soil, vegetation, and terrain properties. In this study, we utilize a distributed hydrologic model to explore the soil moisture and evapotranspiration distributions in a semiarid mountain basin. Results indicate a reliable and consistent model performance at the point and catchment scales for a set of tested hydrologic states and fluxes. Distributed model simulations reveal that soil, vegetation, and terrain controls on catchment spatial patterns vary according to the wetness state in a manner similar to that found across a wider range of climate conditions. Spatiotemporal variations in soil moisture and evapotranspiration exhibit hysteresis as an emergent pattern induced by climate variability and the underlying hydrologic interactions in the catchment. Copyright 2010 by the American Geophysical Union.