Estimating Groundwater Pumping and Return flow Based On Hydrologic Recession Analysis

摘要

Hydrologic processes have been affected by human activities which include both direct andindirect interferences. The indirect human interferences such as land use and land cover changehave been studied and modeled in many watersheds around the world. These kinds of humaninterferences, resulting in land surface changes, usually affect the rising limb and the peak of ahydrograph. The streamflow recession process, are not much affected by the land surfacecondition and the impacts of indirect human interferences are trivial; however the direct humaninterferences such as water withdrawals and return flows may affect the recession dynamicssignificantly. Direct human interferences are difficult to observe and model, and are usuallyassumed to be known and additive to streamflow. This paper provides a recession analysisinvolving groundwater pumping and effluent discharge as variables. The analysis is applied toan urban watershed in the Chicago area. Based on the historical streamflow observation duringthe last half century, the analysis provides results that explain the impact of direct humanactivities on the streamflow recession process. Moreover, the analytical method allowsretrieving human water use data such as groundwater pumping and return flow, which changewith socioeconomic development and policy reforms, as long as the streamflow observation isavailable and long enough. The analysis is verified with the data of the case study watershed andcan be applied to other watersheds under intensive human interferences.