Assessment of water resources in the porous formations from Muong Thanh value by numerical modelling

Abstract

Muong Thanh valley located in the middle of Dien Bien is home to 80.000 people, including Kinh, Thai, Dao, and H’Mong ethnic groups. Here, underground water is the main source of food and drink for local people. The groundwater in porous formations in the Muong Thanh valley area mainly exists in two aquifers qh, qp belonging to Holocene (aQ21-2) and Pleistocene (aQ13, apQ13) formations. Hydrogeological survey results and groundwater monitoring data showed that groundwater in these formations is mainly from i) Rainwater sources, ii) Seepage from Nam Rom river, and iii) Percolate from outside. Applying numerical methods by using Visual Modflow to estimate inflow and outflow components exhibited that the total underground water reserves in the detached formations in the Muong Thanh valley area vary from 25,154 to 30,973 m3/day between dry and rainy seasons, including recharge from rainfall (from 191 to 5,418 m3/day) and seepage from Nam Rom river (from 12,046 to 23,147 m3/day). The total amount of replenished water fluctuates seasonally, from 13,112 to 29,464 m3/day. The current exploitation water flow is about 2,000 m3/day, much smaller than the total amount of replenished water, showing that the exploitation level is within safe limits.