HR: 0800h
AN: H21A-1308    [Abstracts]
TI: Investigation of the Relative Roles of Climate Seasonality and Landscape Properties on Mean Annual and Monthly Water Balances
AU: * Yokoo, Y
EM: yokoo@ashitech.ac.jp
AF: Department of Civil Engineering, Ashikaga Institute of Technology, 268-1 Ohmae-cho, Ashikaga, Tochigi, 326-8558 Japan
AU: Sivapalan, M
EM: sivapala@uiuc.edu
AF: Departments of Geography and Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 220 Davenport Hall, 607 S. Mathews Avenue, Urbana, IL 61801 United States
AB: This paper explores the effects of climate seasonality, soil characteristics, and topography on annual and monthly water balances with conservation equations governing hillslope responses derived by Reggiani et al. (2000). Numerical simulations for 4,500 different hypothetical basins helped to understand the controls on annual and monthly water balances from multiple viewpoints. The results on annual water balance showed that climate seasonality decreased annual evapotranspiration and this tendency becomes stronger if the basin is mildly sloped and covered by silty loam type soil in a climate that is dominated by storms. The summary of results on monthly water balance is as follows: (1) seasonality becomes more significant for monthly water balance when precipitation and potential evapotranspiration are of opposite phase; (2) surface and subsurface runoff respond quickly and become more seasonal under humid climate; (3) soil saturation degree and evapotranspiration experience strong seasonality and longer delay time against precipitation, if precipitation and potential evapotranspiration are of opposite phase under arid climate; (4) soil saturation degree and surface runoff show strong seasonality and longer delay time against precipitation, when basin_fs soil has higher storage capacity (higher porosity and deep soil); (5) soils with lower storage capacity cause strong seasonality and short delay time against precipitation to soil saturation degree and surface runoff; (6) groundwater level and subsurface runoff show strong seasonality and long delay time against precipitation when soil has high drainability (higher hydraulic conductivity and steep topography); and (7) soil with lower drainability causes strong seasonality and short delay time against precipitation to soil saturation degree and surface runoff. We verified the adequacy and reality of our simulation based results through comparisons with observed data oriented results in previous research. We can confirm that our results partly agree with those of Milly (1994) and Oki et al. (1995), and believe that these simulation results from a theoretically derived water balance model reflect reality reasonably well, although future data analysis will help confirm these results or help to improve theory.
DE: 1830 Groundwater/surface water interaction
DE: 1847 Modeling
DE: 1860 Streamflow
DE: 1866 Soil moisture
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005