Impacts of Urbanization on Watershed Hydrology and Runoff Water Quality of a Watershed: A Review

The natural hydrology and runoff water quality of a watershed change due to the conversion of pervious surfaces into impervious surfaces. This article reviews the effects of urbanization on watershed hydrology and runoff water quality. The approach of this study is based on a literature review focusing on urbanization and its impacts on watershed hydrology and runoff water quality. The literature review consists of an analysis of one hundred and seven peer-reviewed articles published from 1976 to 2022. The search used keywords such as land use, land cover, hydrology, and water quality. Most of these studies observed an increase in urbanization. The hydrologic effects of urbanization discussed in the studies include an increased surface runoff and a decreased groundwater flow and evapotranspiration rate. These areas need a detailed characterization to model the changes and their effects. Therefore, watershed hydrologic modeling techniques and numerical models are discussed in this review. Sediment and pollutant loadings depend on the type of land use and cover changes of a watershed. In the case of urbanization, building roofs, parking lots, and roads serve as host surfaces, where pollutants accumulate and wash off during a storm. The changes in sediment and pollutant loadings are also well documented in the studies reviewed. An overview of the methods used by researchers to model these pollutants is provided. The study offers insight into the modeling tools and techniques used to estimate the impacts of urbanization on watershed hydrology and runoff water quality.