A DISTRIBUTED AND OBJECT-ORIENTED RAINFALL-RUNOFF SIMULATION MODEL WITH HIGH SPATIAL RESOLUTION IMPERVIOUS SURFACE

摘要

In this study we develop a distributed and object-oriented rainfall-runoff simulation (DORS) model with incorporation of 1-m high spatial resolution impervious surface area (ISA) data obtained from true-color digital orthophoto. This physically based model simulates hydrologic processes of precipitation interception, infiltration, evaporation and evapotranspiration, soil moisture and change of water table depth, runoff routing, ground water routing and channel routing. The model takes land-cover based objects as spatial units to reduce data volume, increase computational efficiency, strengthen representation of watersheds and utilize the data in various scales. The model is able to extract the relationship between neighboring objects such as slope, flow direction and border length and uses them for the runoff and ground water routing. We validate the DORS model within two watersheds with USGS discharge measurements in the state of Rhode Island. Total relative variation, ratio of absolute error, and Nash coefficient are -3.6percent, 9.6percent, and 0.998 for one watershed and 3percent, 12.4percent and 0.8 for another. The validation result indicates that the DORS model is capable of capturing the relationship between rainfall and runoff in the study watersheds. The comparison between results using high and low spatial resolution ISA demonstrates that incorporation of high spatial resolution ISA improves obviously the performance of hydrologic model.