| Land use and land cover (LULC) change from forest to urban impervious cover can affect watershed hydrology by altering evapotranspiration, infiltration, surface runoff, and groundwater recharge. This research evaluated the impact of LULC change on watershed-scale hydrologic behavior under different development scenarios within a hydrological modeling framework. A new IU Health Bloomington Hospital and Academic Health Center is going to be constructed in Bloomington, Indiana, which will affect water yield patterns within the Griffy Lake watershed. In this study, the Soil and Water Assessment Tool (SWAT) hydrologic model was used to assess changes in streamflow for the study area. The timing and magnitude of peak flow, base flow have also been examined. The construction area is assumed to be transformed from grass and deciduous forest into high, medium and low density developed areas. Using a calibrated and validated SWAT model, the changes in streamflow generation were assessed for low, medium and high intensity development scenarios, as well as other hydrological components such as surface runoff, lateral flow, and evapotranspiration, and soil water storage. Results indicated that the discharge at the outlet would increase by approximately 2%, 3.5% and 6% under the high, medium and low density development scenarios, respectively, compared to the current discharge. For the two most impacted sub-watersheds due to the construction, the mean discharge would increase by 15%, 23% and 40% for low, medium and high intensity development, respectively, compared to the baseline. The simulated results also indicated the decrease in low flow frequency and the increase in peak flow frequency. The frequency and intensity of urban floods can also be expected to increase. The mean annual surface runoff would increase by 58%, 84% and 137% for low, medium and high intensity development. Both the evapotranspiration and soil water storages would decrease, but total water yield would increase for the high development scenario compare to the baseline. This comparison between simulated flows under the current and the different urban development scenarios provides an insight for future water management plans of the Griffy Lake watershed. |
