A study on the hydro-geologic factors that affect streamflow depletion

摘要

Evaluation of streamflow depletion induced by groundwater pumping is important for watershed management. Many analytical and numerical solutions exist for estimating depletion for various hydro-geologic scenarios. Numerical models are time consuming and require significant data input, and moreover, are problem-specific. Analytical models are convenient because of their ease of use, minimum data requirements, and instantaneous solutions, but are only applicable for idealistic scenarios. In many cases, analytical models are used for decision making on water-withdrawal permits, because they are assumed to offer conservative estimates of depletion. However, a systematic study of the applicability of these analytical models has not been done. In this research, we critically evaluate the performance of the analytical models in complex hydro-geologic settings, and list the factors that most significantly impact depletions. On the basis of this study, we find that the analytical models perform satisfactorily as a screening-level tool, though there are some situations when they perform poorly. The factors that most significantly impact streamflow depletion are spatial variability in hydraulic conductivity and the presence of other sources of water, such as lakes and wetlands. The analytical models do make conservative predictions of streamflow depletion especially for the most vulnerable streams.