Deciding on a suitable location for groundwater abstraction borehole to minimize the impact on the stream flows of adjacent river

A study was carried out for the purpose of deciding on a suitable location for the borehole, using the UK Environment Agency IGARF-1 model, so that impact on the stream flows to be minimized. In this study, a model is considered in which a stream crosses a plain, flowing over a sandstone aquifer. It is proposed to install a groundwater abstraction borehole near to the stream to be used to supplement irrigation water during summer drought periods. For this, the IGARF-1 model for stream-aquifer interactions was used to determine the best location for the abstraction borehole within the land area available. The results indicate the best location for the abstraction borehole (i.e. the location which minimize the impact on stream flows) is to be at some perpendicular distance to the stream. Increasing the perpendicular distance of the borehole to the stream causes a decrease in the river flow depletion rate during the periods of drought in the case of the abstraction borehole to be in the area of the unconfined aquifer. Also in this case, as this distance increases, the river flow depletion rate during the periods of drought in the case of the abstraction borehole to be in the area of the unconfined aquifer. Also in this case, as this distance increases, the river flow depletion rate continues to increase, and then drops down, but that is not in the case of the abstraction borehole when located in the confined aquifer. Decreasing transmissivity causes even less flow depletion rate during the periods of drought. However, increasing transmissivity increases the flow depletion rate. Unlike transmissivety, specific yield and storativity have opposite effect on the flow depletion rate, i.e. increasing the specific yield or storativity decreases the flow depletion rate to the least possible rate during the drought periods.

کلیدواژه ها:

Groundwater abstraction borehole ، river flow depletion rate ، confined aquifer ، unconfined aquifer ، transmissivity ، specific yield ، storativity