Hydrologic Response in an Urban Watershed as 2 Affected by Climate and Land Use Change 3

Abstract

The change in both streamflow and baseflow in urban catchments has received significant 10 attention in the latest decades as a result of their drastic variability. In this research, effects of climate 11 variation and dynamics of land use are measured separately and in combination on streamflow and 12 baseflow in the Little Eagle Creek (LEC) watershed (Indianapolis, Indiana). These effects are 13 examined using land use maps, statistical tests, and hydrological modeling. Transition matrix 14 analysis was used to investigate the change in land use between 1992 and 2011. Temporal trends 15 and changes in meteorological data were evaluated from 1980-2017 using the Mann-Kendall test. 16 Changes in streamflow and baseflow were assessed using the Soil and Water Assessment Tool 17 (SWAT) hydrological model using multiple scenarios that varied in land use and climate change. 18 Evaluation of the model outputs showed streamflow and baseflow in LEC are well represented 19 using SWAT; however, comparing the calibration and validation period showed SWAT performs 20 better for the calibration. During 1992-2011, roughly 30% of the watershed experienced change, 21 typically cultivated agricultural areas became urbanized. Baseflow is significantly affected by the 22 observed urbanization; however, the combination of land and climate variability has a larger effect 23 on the baseflow in LEC. Generally, the variability in the baseflow and streamflow appears to be 24 heavily driven by the response to climate change in comparison to variability due to altered land 25 use. The results reported herein expand the current understanding of variation in hydrological 26 components, and provides useful information for management planning regarding water resources, 27 as well as water and soil conservation in urban watersheds in Indiana and beyond. 28