Evaluation of MAR Methods for Semi-Arid, Cold Regions

Mongolia is a semi-arid, highly continental region with highly variable precipitation andriver discharge. The groundwater aquifer located near Ulaanbaatar, the capital city of Mongolia, isthe only one source for city water supply consumption, and it is important to ensure thatgroundwater is available now and in the future. The main watercourse near the capital city is theTuul River, fed by precipitation in the Khentii Mountains. The semi-arid and cold environmentshows high variability in precipitation and river discharge. However, due to absence ofprecipitation in winter and spring, the riverbed usually runs dry during these times of the year, andweather observations show that the dry period has been extending in recent years. However, inparallel with urban development, the extended groundwater aquifer has shown a clear decline, andthe groundwater levels have dropped significantly. Therefore, a groundwater management systembased on managed aquifer recharge is proposed, and a strategy to implement these measures in theTuul River valley is presented in this paper. This strategy consists of the enhancement of naturalrecharge rates during the wet summer from the northern drainage canal, an additional increase ingroundwater recharge through melting the ice storage in the dry period, as well as the constructionof underground dams to accumulate groundwater and a surface water reservoir that releases aconstant discharge in the outlet. To increase natural recharge rates of groundwater during the earlydry period through the melting ice storage period, the MATLAB icing code, which was written forice storage for limited and unlimited areas, was considered through finite element subsurfaceFLOW (FEFLOW) simulation scenarios as a water source in ice form on the surface. A study of theartificial permafrost of underground as an ice dam was processed in FEFLOW simulation scenariosfor accumulating groundwater resources. The results of these artificial recharging methods wereindividually calculated, combined, and compared with the surface reservoir, which releases aconstant discharge through the dam. In this paper, new ideas are presented involving managedaquifer recharge&mdash
MAR methods, and include application to aufeis, a mass of layered ice forgroundwater recharge by melting. Additionally, the accumulation of groundwater using artificialpermafrost is used as an underground dam. In addition, was considered recharging scenario onlywith constant release water amount from water reservoir also with all MAR methods together withreservoir combination.