GroMoPo Metadata for Lawra District GMS model

The groundwater flow system in a crystalline aquifer system in parts of Northern Ghana was simulated and calibrated under steady-state conditions. The objective was to estimate the regional distribution of a key aquifer hydraulic parameter (the hydraulic conductivity) and recharge and also to predict possible effects of different abstraction and groundwater recharge scenarios on the sustainability of groundwater resources in the area. The study finds that the hydraulic conductivity field is quite homogeneous and has values ranging between 1.70 and 2.24 m/day. There is an apparent dominance of regional groundwater flow systems compared to local flow systems. This is probably attributed to the homogeneity in the hydraulic conductivity field and the absence of complex local relief. Estimated groundwater recharge ranges between 0.036 and 0.164 m/yr representing 3.6 and 16.4 % of the local annual precipitation, respectively. Substantial subsurface inflows and outflows have also been simulated through general head boundaries. The simulation suggests that under the current conditions of groundwater recharge estimated at calibration, the system can sustain increment in groundwater abstraction by up to 50 % without any significant changes in the groundwater flow geometry and drawdowns in the hydraulic heads. However, significant drawdowns will be expected in the wake of 100 % increment in groundwater abstraction and a reduction in recharge by 10 % during the 20-year period. Under such conditions, the flow geometry will significantly be altered and a reversal in groundwater flow will be observed.针对加纳北部部分区域的结晶岩含水层系统，本研究在稳态条件下对其地下水流系统开展了模拟与校准工作。本次研究的目标为：估算核心含水层水力参数（导水系数，hydraulic conductivity）与地下水补给量的区域分布特征，同时预测不同开采方案与地下水补给情景对该区域地下水资源可持续性的潜在影响。研究结果表明，研究区导水系数场整体均质性较强，数值区间为1.70~2.24 m/d。相较于局部地下水流系统，区域地下水流系统占据明显主导地位，这一现象大概率源于导水系数场的均质性以及研究区缺乏复杂局部地形起伏。估算得到的地下水补给量区间为0.036~0.164 m/yr，分别占当地年降水量的3.6%与16.4%。研究还通过广义水头边界模拟得到了可观的地下侧向流入与流出量。模拟结果显示，在校准阶段估算的当前地下水补给条件下，当地地下水开采量最多可提升50%，而地下水流场形态与含水层水头降深均不会出现显著变化。但如果在20年周期内将地下水开采量提升100%且补给量减少10%，则会出现显著的水头降深；在此情景下，地下水流场形态将发生显著改变，甚至出现地下水流向逆转的现象。