Urban Surface Characteristics Study Using Time-Area Function Model: A Case Study in Saudi Arabia

摘要

The study of surface characteristics in urban catchments is critical step for stormwater planning, design and management. At present, nearly all GIS-based distributed parameter models for rainfall runoff calculation neglect the urban environment properties in Digital Elevation Models (DEMs), thus simulation results by these models were hardly reliable especially in urban areas. In this study, a physical-based hydrologic model using time-area function method was developed for unit hydrograph derivation taking surface characteristics of urban environment into consideration. With the growing availability of high-resolution DEMs produced by airborne LiDAR, the basic approach was to calculate the runoff travel time from each cell of DEMs in the watershed to the outlet by determining the flow path and accumulating the travel time through each cell along the path. This standalone model, named Time-Area Function (TAF) model, was then applied to a city in Saudi Arabia and was compared with a conventional model. It showed that for the case study TAF model could give more reliable and reasonable results. In conclusion, rainfall runoff analysis in urban environment requires additional properties to be considered and modelled, and significant improvements can be achieved by approaches as implemented and applied in TAF model integrating urbanization components, such as buildings, varying landuse, open channels and drainage system into the model.