Stochastic analysis of the impacts of rainfall patterns on groundwater recharge.

摘要

Potential climate change can impact groundwater recharge. Climate chance scenarios were constructed taking into account uncertainty concerning stochastic generation patterns of precipitation and change in the recharge. Because groundwater is directly connected to near-surface hydrologic processes, it intricately connected to the overall hydrologic cycle and could be directly affected by climatic change. Changes in groundwater recharge are likely to result from changes in the annual and seasonal distribution of precipitation. The relationship between the stochastic precipitation that infiltrates and recharges groundwater is the subject of active studies. This is an unprecedented and important research area. The goal of the present research is to attempt to characterize impacts on groundwater recharge by developing potential precipitation patterns and simulating the groundwater recharge in a groundwater simulation model. The stochastic generation of a precipitation model is estimated by adopting two processes for the rainfall. One model is a first order Markov chain. The second model used an exponential distribution model that was fitted to the historical time series of the amount of rain for rainy days. Based on the US Global Change Research Program report's of general predictions for the climate in northeastern North America over the next 100 years, six scenarios for a synthetic time series of precipitation ware developed.;Precipitation is assumed to increase or decrease, with an average change ranging between 5 and 45 percent with 10 percent increments. The generated synthetic time series of precipitation were used in the GSFLOW model. Characteristic statistics and the frequency analysis of the recharge scenarios were estimated. The investigation shows that for the different scenarios, the recharge can be affected and changed to a much greater degree than the percentage change in precipitation. For example a scenario of 25% increase in precipitation showed an increase in recharge of approximately 60% while a 25% decrease in precipitation showed a 70% decrease in recharge.