Roof aquifer water abundance evaluation: a case study in Taigemiao, China

To ensure safe mining of the Taigemiao no. 3 mine field in Inner Mongolia, China, it is very important to make clear the roof aquifer water abundance distribution feature. On the basis of collecting the main controlling factors of aquifer water abundance from the geological and hydrogeological prospecting data of the study area, the no. 2 coal seam roof aquifer water abundance of Taigemiao no. 3 mine field was analyzed and evaluated using three methods. The first method is analytic hierarchy process (AHP)-type water-richness index method (AHP-type WIM) which is commonly used. But AHP is relatively subjective, so we trying to use a more objective method which is weighed gray relational degree method (WGRDM); this method mainly used pure data analyzing, it is better than AHP-type WIM but still not perfect, so the comprehensive weighted method (CWM) is put forward by adopting the advantage of the former two methods. In order to assess the accuracy rate of the three methods quantificationally, the evaluation results of the three methods are compared respectively with the measured unit water inflow which can directly reflect the aquifer water abundance, which shows that the WGRDM is more accurate than AHP-type WIM, and the CWM is more scientific and accurate in both weight calculation and water abundance grading. The superiority of CWM is more obvious when there are too many evaluation factors.