Numerical simulation of groundwater flow in Yanqi Basin, Xinjiang Province, China

Based on the systematic analysis on the lithology of unconsolidated sediment, water head, recharges, discharges, and boundary conditions of groundwater system in Yanqi basin of Xinjiang Province, China, a three-dimensional modular model (MODFLOW) was used to simulate groundwater flow in order to correctly evaluate the groundwater resources which is the base of the reasonable groundwater development. After the model calibration by trial and error method, the simulated head satisfactorily match observed head in the regional water-table aquifer. The simulation period was from 1 October 1999 to 31 December 2000, and the groundwater balance in 2000 was analyzed. The simulation results indicate that the total recharge was about 116.9x10(6)m(3)/a, and the total discharge was 114.9x10(6)m(3) in 2000, the little difference indicates the groundwater system was in balance. For the shallow aquifer, the irrigation recharge and lateral inflow were the main recharge sources and they were 59.7x106m3 and 49.4x106m3 accounting for 51.5% and 42.3% of all recharge in 2000, respectively. Evaporation is the main discharge of shallow aquifer accounting for 46.6% of all discharge in 2000. For the deep aquifers, the artificial abstraction is the major discharge, which accounted for 8.0% of total discharge.