Evaluating the spatial distribution of water balance in a small watershed, Pennsylvania

✍ Scribed by Zhongbo Yu; W. J. Gburek; F. W. Schwartz

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 760 KB
• Volume: 14
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/(sici)1099-1085(20000415)14:5<941::aid-hyp2>3.0.co;2-s

✦ Synopsis

A conceptual water-balance model was modi®ed from a point application to be distributed for evaluating the spatial distribution of watershed water balance based on daily precipitation, temperature and other hydrological parameters. The model was calibrated by comparing simulated daily variation in soil moisture with ®eld observed data and results of another model that simulates the vertical soil moisture ¯ow by numerically solving Richards' equation. The impacts of soil and land use on the hydrological components of the water balance, such as evapotranspiration, soil moisture de®cit, runo and subsurface drainage, were evaluated with the calibrated model in this study. Given the same meteorological conditions and land use, the soil moisture de®cit, evapotranspiration and surface runo increase, and subsurface drainage decreases, as the available water capacity of soil increases. Among various land uses, alfalfa produced high soil moisture de®cit and evapotranspiration and lower surface runo and subsurface drainage, whereas soybeans produced an opposite trend. The simulated distribution of various hydrological components shows the combined eect of soil and land use. Simulated hydrological components compare well with observed data. The study demonstrated that the distributed water balance approach is ecient and has advantages over the use of single average value of hydrological variables and the application at a single point in the traditional practice.