Calculation of Potential Groundwater Resources in Orkhon River Basin

Available groundwater research work and data levels are very limited due to the wide territory of our country. Potential Groundwater resources need to be calculated by basin to implement Integrated Water Resources Management Plans. For this purpose, previously the calculations were done twice in the Orkhon River Basin. The last calculation was done 10 years ago, therefore Integrated Water Resources Management Plan needs to be redeveloped, using updated research work and data levels. The Orkhon River is one of the biggest rivers in Mongolia, rising from Khangai Mountain Range and flowing into the Selenge River. The Orkhon River Basin includes the Tuul, Kharaa, and Yeruu rivers basins which rise in the Khentii Mountains. For the first time, a hydrogeological structure map of the basin was developed which analyzed and systemized the hydrogeological structure, the morphostructure factors, and the hydraulic properties of the hydrogeological formations distributed in the Orkhon River Basin. There are two types of hydrogeological basins and three types of hydrogeological massifs in the basin. This paper presents the calculation of the Potential Groundwater Resources (PGR) in the Orkhon River Basin based on groundwater well data, reports of groundwater exploration and research works, and the hydrogeological maps at a scale of 1:500,000. As a result of this calculation, there are 1.99 km3 of PGR in this basin.The largest resources are found in the linear intermountain hydrogeological basin which occupies 98 percent of the total PGR. Further improvement of the quality and standards of water research remains an important issue for hydrogeologists today.