الملخص الإنجليزي
Al-Khoudh well-field is considered as one of the most essential groundwater resources for Muscat
Governorate. Currently, there are more than 61 pumping wells in operation within this well-field
area, clustered around the Al-Khoudh recharge dam, which is accounting for about 50,000 m3
of
water volume pumped every day. In recent years, population density in the surrounding area of the
well-field is increasing at an unprecedented rate. Thus, increasing water abstraction and
deterioration in groundwater quality has posed a threat to the sustainability of this well-field.
In this study, different scenarios were simulated to understand the aquifer response to varying rates
of water abstraction in addition to the impacts of urbanization in terms of practices at surrounding
residential areas and cultivated lands. Two models were utilized in this study, namely MODFLOW
and MT3DMS. The Transient State MODFLOW was used to simulate groundwater flow for a
period of 22 years (2018-2040).
The simulation results showed that the overall mean water levels of all observation wells will be
reduced by 2.896 m at July, 2040. In the increased abstraction scenario of 10%, 20% and 30%, the
results have indicated that the overall mean water levels have decreased by 0.657 m, 1.313 m and
1.617 m, respectively. Similarly, the water abstraction was reduced with various percentages of
10%, 20% and 30%, in which the results showed that the overall mean water levels will be
increased by 0.64 m, 1.283 m and 1.921 m, respectively. For the increased recharge scenario of
10%, 20% and 30%, the overall mean water levels have increased by 0.04 m, 0.079 m and 0.119
m, respectively, while in the reduced recharge scenario by 10%, 20% and 30%, the mean water
levels have decreased by 0.043 m, 0.085 m and 0.128 m, respectively. In the flash flood scenario,
the overall water levels of all observation wells have increased by 0.00606 m.
MT3DMS model was utilized for simulation of Nitrate transport and concentration calculation in
the study area. It was found that the maximum and minimum concentrations of Nitrate at
December, 2040 will be 26.4803 mg/L and 0.0038 mg/L, respectively.
The various simulated scenarios in this study have elaborated the impacts associated with extensive
water abstractions as well as impacts of increasing urbanization. The findings of this study can
assist the decision makers to initiate the suitable remedial counter measures which can mitigate
the impacts of the increased water abstraction and Nitrate discharge.
