Impacts of land use and urbanization on unit hydrograph and peak discharge: A case study of two watersheds in Houston area

Abstract:

This study is aimed to determine the potentially negative effects of change in land use, in particular the expansion of impervious surfaces on hydrological processes such as peak discharge and lag time in the Buffalo Bayou and Goose Creek watersheds located in the Houston area. Buffalo Bayou watershed is predominantly a highly developed basin while the Goose Creek watershed is mainly underdeveloped. Based on land use data from the last two decades, ArcGIS Pro was used to analyze the land-use change within the watershed from which a map depicting the change was produced. A total of six-unit hydrographs were created and used for the analysis of two major events for each decade since 2000. The unit hydrographs provide a lag time that can be compared to the land-use change and ultimately show the correlation between the expansion of impervious cover and an increased lag time. The unit hydrographs were also used to detect a positive trend in peak discharge across the 20-year time frame. The study revealed larger inconsistencies in lag times in highly developed watershed basins, compared to the rise of developed land and the associated decrease in lag time in a mostly underdeveloped watershed. Results from this study will aid city planners in designing and implementing a more effective storm response plan for the City of Houston. The results also highlight the need to reduce the development of impervious surfaces in the city and across the Buffalo Bayou watershed to avoid future catastrophic flooding. This project also dives into further discussion regarding other possible factors for the disparities found in the analysis of the more urbanized watershed.