Impact of Urbanization on Runoff and Infiltration in Walnut Gulch Experimental Watershed

Document Type

Conference Proceeding

Publication Date


Publication Title

Watershed Management Conference 2020


American Society of Civil Engineers

Publisher Location

Henderson, NV

First page number:


Last page number:



Urbanization disrupts the natural water balance by increasing the runoff and reducing infiltration. This study examines the impact of change in impervious surface on runoff response and infiltration of Walnut Gulch Experimental Watershed. The hydrological model of the watershed was developed using Hydrologic Engineering Centre-Geospatial Hydrologic Modeling System (HEC-GeoHMS) software, and simulation was performed using Hydrologic Engineering Centre-Hydrologic Modeling System (HEC-HMS). Precipitation, elevation, and percentage imperviousness data were used as model inputs for the HEC-HMS model. Land cover and soil characteristics of the watershed are used to adjust the curve number value. The model was calibrated and validated using streamflow data acquired from the U.S. Department of Agriculture (USDA) website. The event-based rainfall data was obtained from five meteorological stations for the year 2012. Urbanization what-if scenarios were considered by altering the percentage of impervious surface. Soil conservation service-curve number (SCS-CN) method was used for calculation of loss and SCS-unit hydrograph method to transform the flow. The impact of urbanization on volume of runoff and infiltration rate was studied. The simulation results of HEC-HMS model show that the increase of impervious land cover increases the volume of runoff significantly. In addition, infiltration decreases correspondingly, which can result in a deficit of groundwater supply. The results from this study will be useful to assess the impact of urbanization on runoff and infiltration of the watershed. The analysis of the results also reflects the significance of considering the effects of urbanization in hydrological modeling.


Municipal water; Runoff; Urban areas; Infiltration; Simulation models; Systems engineering; Hydrologic engineering; Hydrologic models


Water Resource Management



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