Application of groundwater flow model in assessing aquifer layers interaction in arid catchment area
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ORIGINAL PAPER
Application of groundwater flow model in assessing aquifer layers interaction in arid catchment area S. Al‑Hashmi1 · L. Gunawardhana1 · A. Sana1 · M. Baawain1 Received: 18 September 2019 / Revised: 9 April 2020 / Accepted: 8 June 2020 © Islamic Azad University (IAU) 2020
Abstract Sustainable groundwater aquifers are critical in arid and semiarid countries due to the scarcity of surface water and precipitation. Management of groundwater resources requires estimation of aquifer properties and interaction between multilayers in heterogeneous aquifers. A three-dimensional groundwater flow model was implemented to simulate a complex multilayer aquifer in Oman. Steady-state model was calibrated using groundwater level data in July 2016. Both the automated parameter calibration technique and manual trial and error method were applied for calibrating hydraulic conductivity, groundwater recharge, and anisotropy of soil layers. The optimum set of parameters of 14 observation wells was obtained from the simulation with minimum root mean square error of 0.8 m for groundwater water level. The calibrated model was validated using measured data for October 2016, and root mean square error was found to be 0.81 m for groundwater water level. Among the observation wells which were used in the above analysis, 4 of them were directed to different aquifer depths and each two observation wells were in the same location. These two sets of wells, therefore, were used for analyzing interactions among different aquifer layers. Results showed that increased pumping rates enhanced water transfer between multilayers due to increased hydraulic gradient. The effect was more dominant in layers with high vertical hydraulic conductivity. Also, the sensitivity analysis was performed and results indicated that the predicted water level was less sensitive to vertical anisotropy. The findings of this study could be useful for decision-makers for better management of groundwater resources in arid regions. Keywords MODFLOW · Multilayer aquifer · Numerical groundwater model · Wadi Samail catchment
Introduction Groundwater aquifers play a major role in ecosystem sustenance in different parts of the world. Sustainable groundwater aquifers are critical in arid and semiarid regions due to the scarcity of precipitation and surface water. Effective management of groundwater resources requires accurate knowledge of aquifer properties and a reasonable understanding of the interaction between multilayers in heterogeneous aquifers. In nature, there is no homogeneous aquifer and aquifer properties vary everywhere (Barlow and Leake 2012). Editorial responsibility: M. Abbaspour. * M. Baawain [email protected] 1
Department of Civil and Architectural Engineering, Sultan Qaboos University, Al‑Khod, 123 Muscat, Oman
Heterogeneous aquifer refers to the one with an uneven spatial distribution of porosity and hydraulic conductivity. The heterogeneity may be enhanced due to cementation, compaction, fracturing, and dissolution processes which create seco
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