Modelling Groundwater Hydraulics to Design a Groundwater Level Monitoring Network for Sustainable Management of Fresh Groundwater Lens in Lower Indus Basin, Pakistan

Abstract

The over-extraction of groundwater from thin fresh groundwater lenses is a threat to the livelihood of farmers in the Lower Indus Basin (LIB). It is essential to monitor and regulate this pumping to sustain fresh groundwater lenses. In this study, we applied a modelling approach in combination with geostatistical analysis to identify the critical locations to monitor the groundwater levels for sustaining fresh groundwater in the LIB. Our approach included four steps: (i) simulating temporal heads using a calibrated hydrogeological model; (ii) sampling monitoring locations using a hexagonal pattern of sampling; (iii) applying principal component analysis (PCA) of the temporal head observations, and selecting high scoring locations from the PCA; and (iv) minimizing the observation points to represent the water level contours. The calibrated model was able to replicate the hydro-dynamic behavior of the study area, with a root mean square of 0.95 and an absolute residual mean of 0.74 m. The hexagonal pattern of spatial sampling resulted in a 195 point network, but PCA reduced this network to 135 points and contour classification reduced it even further to 59 points. The 195, 135, and 59 point networks represented the water levels with average standard errors of 0.098, 0.318, and 0.610 m, respectively. Long-term simulations with increased pumping showed that the water levels would best be assessed by 195 monitoring points, although 135 and 59 points would represent the depleting area but would not capture the water logging area.

Statistical Analysis of Climate Trends and Impacts on Groundwater Sustainability in the Lower Indus Basin

“…Several studies in the Central Indus Basin used groundwater modelling to assess the impact of external stresses (e.g., [14,15]). In the Lower Indus Basin, groundwater modelling studies have been conducted at small spatial scales to study groundwater hydraulics and hydro salinity behaviour (e.g., [16][17][18]). Studies related to the impacts of climatic change on groundwater in the Lower Indus Basin are limited, especially at the regional scale.…”

Mapping the optimization of groundwater abstraction research: A bibliometric review in the context of South Asian region

“…Ahmed et al [ 19 ] demonstrated a modelling strategy combined with geostatistical analysis to highlight the key areas for groundwater level monitoring to maintain fresh groundwater in the Lower Indus Basin, Sindh, Pakistan. Khan et al [ 20 ] evaluated the optimization of groundwater conditioning factors, the evaluation of groundwater potential, and other parameters for groundwater resource management in Northern Pakistan.…”