Sunday, September 22, 2019

Evaluation of MAR methods for semi-arid, cold region

Evaluation of MAR methods for semi-arid, cold region

Nasanbayar Narantsogt,
Karlsruhe University of Technology, Karlsruhe Germany
                                                                                 
Abstract:
The semi-arid and cold environment shows a high variability in precipitation and river discharge. The groundwater aquifer located near Ulaanbaatar capital city of Mongolia, is the only source of water supply and it is important to ensure that groundwater is available now and for the future.
The main watercourse near the city is the Tuul River, fed by precipitation in the nearby Khentii Mountains. However, due to the absence of precipitation during winter and spring, the riverbed usually runs dry during that time, and observations show that the dry period has been extending within the last years.
However, in parallel with the city’s development, the extended groundwater aquifer shows a clear decline, and the groundwater levels drop significantly. Therefore, a groundwater management system based on managed aquifer recharge is proposed and a strategy to implement these measures in the Tuul River valley is presented in this paper. It consists of an enhancement of natural recharge rates during the summer wet period, an increase of groundwater recharge through melting ice storage in dry period, as well as the construction of underground dams to accumulate groundwater also surface water reservoir which release constant discharge in outlet.  
The MATLAB icing code written for ice storage on limited and unlimited area was considered in FEFLOW simulation scenarios as water source in ice form on surface to increase groundwater natural recharge rates during the early dry period, through melting ice storages.  The study of underground artificial permafrost as ice dam was processed in FEFLOW simulation scenarios for accumulating groundwater resources. The results of these artificial recharging methods calculated individually and combined also compared with surface reservoir which release constant discharge through dam.