Responses of Streamflow and Baseflow Hydrology to Climate Variability and Land Use Dynamics in an Urban Watershed

The change in both streamflow and baseflow in urban catchments has received considerable attention owing to their dramatic variation in recent decades. In this research, the impact of separate and combined impacts of land use and climate variability on Little Eagle Creek (LEC) watershed in Indianapolis, Indiana were investigated, by combining usage of statistical tests, hydrological modeling and land use maps. The temporal trends and change in meteorological data during 1980-2017 were explored using non-parametric Mann-Kendall and Pettitt tests. Land use changes between 1992 and 2011 were determined using transition matrix analysis. The Soil and Water Assessment Tool (SWAT) hydrological model was used to investigate the variation of streamflow and baseflow under land use change and climate variability scenarios. The year 1998 was used to divide the study period based on meteorological data. Results showed that SWAT performed well in capturing the streamflow and baseflow in LEC; however, it exhibited better performance for the calibration period than for the validation period. During 1992-2011, about 30% of the catchment area experienced land use change, mainly from cultivated areas to urban. The land use change shows a significant effect on baseflow; however, the combination of land use and climate variability have a greater impact on the variation of baseflow in LEC. Overall, variability in climate seems to strongly drive the variability in the baseflow and streamflow response in comparison to their alterations due to land use change. The results obtained provide useful information to improve the current understanding of hydrological components variation and for water resources planning and management as well as soil and water conservation in urban watersheds in Indiana and potentially beyond.