Predicting Urban Runoff under Different Surface Conditions in Xi’an, China with DRAINMOD

Increasing impermeable surface area has become a serious burden for drainage of urban stormwater. It is thus important to know how much surface runoff may be generated by storms of varying intensity and duration, especially on a continual daily basis. In this paper, the field hydrology model-DRAINMOD was used to simulate daily surface runoff under different surface condition in Xi’an, China. As a major hydrological components in DRAINMOD, daily evapotranspirations were calculated with the FAO Penman-Monteith method and read into the model. Infiltration parameters were considered as calibration factors in the modeling process. Available data from a local rainfall-runoff experiment were used for model calibration by matching the model predicted surface runoff with the measured values on an event basis. The calibrated model was then used for long term simulations in order to examine the impact of varying climatic conditions and land cover on urban runoff. The modeling results may provide a practical guidance for city storm water management.