An Improved Potential Groundwater Yield Zonation Method for Sandstone Aquifers and Its Application in Ningxia, China

In Chinese coal mines, hydrogeological research usually lags behind geological exploration. Therefore, methods that use geological exploration data to zone the potential groundwater yield of sandstone aquifers in coal mines with limited hydrogeological data are needed, but their development is a challenge. The geological, tectonic and lithological composition index (GTLCI) model proposed by Yin et al. in 2018 partially solves the above-mentioned problem. However, this model has two shortcomings: (1) the weights of factors in this model are constant, reflecting only the relative importance of different indicators and ignoring changes in each factor and the effects of different combinations; and (2) available drilling data from geological exploration are not used to their full advantage in the model. In this paper, an improved model based on variable weight theory (GTLCI 2.0) is proposed to address these shortcomings. GTLCI 2.0 provides a dynamic weighting mechanism to surmount the limitation of constant weights, incorporates an improved lithological composition index, and makes additional use of core recovery and drilling fluid consumption data. Based on field data from pumping tests, borehole drainage and water inflow during mining, the prediction success rate of GTLCI 2.0 in Ningxia exceeded that of the constant weight model by 21.7%. Moreover, it is usable in other coal mines with similar hydrogeological characteristics.