Distributed hydrological modeling study with the dynamic water yielding mechanism and RS/GIS techniques

摘要

Water yielding in the hydrologic cycle is a temporally and spatially varied process. However, water yielding mechanics expressed in hydrological simulations seldom accurately characterize such dynamic processes thus weakens the simulation capabilitiesof present hydrological modeling systems. In this study a conceptual distributed hydrological model entitled ESSI (infiltration Excess and Saturation excess Soil-water Integration model for hydrology) was developed for flooding simulation and long termwater resource management studies by means of RS, GIS and data mining techniques. This distributed hydrological modeling system has three significant characteristics: 1) capable of determining temporally and spatially varied water yielding mechanics overthe most basic simulated grid by comparing with real-time computed rainfall and soil water variables; 2) excellent weather adoptability to ensure the model perform excellently for either wet and dry watershed conditions; 3) fully distributed simulatingcapabilities enable the model output about 20 distributed hydrological process components in different time scales, i.e. evapotranspiration (potential and actual), canopy storage, and soil moisture contents in different soil depth etc.Calibration and validation of the modeling system was conducted on two carefully selected climatologically typical watersheds in China, one located in the typical humid climate condition of upper stream of the Hanjiang river Basin, gauged by the Jiangkouhydrometric station (drainage area: 2413 km2), and another the Yingluoxia watershed (drainage area: 10029 km2), situated in typical cold and arid Heihe Mountainous region. With the calibrated model parameters and the appropriate combination of hydrological simulating module, ESSI successfully reproduced the flooding events and long term hydrological processes for the both experiment watershed, which implies the model an excellent hydrological simulation tool under various weather conditions.