Sensitivity of soil moisture and evapotranspiration to soils and land use heterogeneity
Rezaul Mahmood, Western Kentucky Univ., Bowling Green, KY; and K. G. Hubbard
Soil moisture (SM) plays an important role in land surface and atmosphere interactions. It modifies energy balance at the surface and the rate of water cycling between land and atmosphere. In this paper we have provided a sensitivity assessment of SM and ET for heterogeneous soil physical properties and for three land uses including irrigated maize, rainfed maize, and grass at climatological scale by using a water balance model. As expected, the study finds increased soil water content in the root zone throughout the year under irrigated farming. Soil water depletes to its lowest level under rainfed corn cultivation due to its complete reliance on naturally available SM. It is found that annual total evapotranspiration (ET) can be up to 34% and 36% higher under irrigated corn compared to rainfed corn and grass, respectively. Sensitivity analysis of the model shows that heterogeneous soils influence SM in the root zone and seasonal total ET estimates at climatological scale. The forcing of soils on SM and ET estimates are within conceptual limit (we need to give a result here or define conceptual limit). It is reported that extremely dry or wet conditions enhanced or muted forcing of soils on SM and ET. Overall, the sensitivity of the SM model to variations in soils inputs supports the premise that atmospheric models should include a realistic characterization of soils to represent the grid scale and sub-grid scale influences.
Session 10, Micro- and Mesoscale Climatology (Parallel with Session 11)
Wednesday, 15 May 2002, 3:15 PM-5:00 PM
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