Groundwater depletion has become a major concern all over the world. Recently, the rapid population growth and need for water and food have placed a massive strain on land and water resources. According to estimates, 42%, 36%, and 27% of the world's groundwater is used for agricultural, domestic, and industrial purposes, respectively. The urban expansion of human settlements and industrial development have affected urban growth patterns, resulting in the conversion of many fertile land surfaces into built-up regions. The effect of urbanization has resulted in the depletion of groundwater. Climate change adds to the strain on groundwater resources and increases the risk of groundwater recharging. The creation and implementation of efficient water management strategies are hampered by a lack of knowledge regarding the changes in groundwater storage. Therefore, the impact of climate change and land use on groundwater resources must be evaluated.
A research study was conducted in Chaj Doab region to investigate both climate and land use change impact on groundwater dynamics.
A sophisticated technique using remote sensing and WaPOR was developed to evaluate various aspects of groundwater recharge in Chaj Doab, Pakistan. This approach provides a comprehensive framework for estimating the spatiotemporal variations of land use and its impact on groundwater and assessing climate-induced changes in evapotranspiration and their impact on groundwater changes. Satellite data helped in quantifying relationships across many geographical and temporal aspects.
The study quantified various factors, including evapotranspiration, Groundwater consumption and groundwater recharge. These variables were examined to understand their interconnections within the Chaj Doab region. The FAO WaPOR was used to calculate geographically distributed estimates of evapotranspiration (Eto) rates. These estimates were their impact on groundwater changes estimates obtained by the remote sensing technique.
The study found that Chaj Doab experienced a significant increase in built-up areas from 117.99 km² (0.86%) to 2504.25 km² (18.34%), while dense vegetation decreased from 13091.77 km² (95.91%) to 9761.99 km² (71.51%) from 2013 to 2023. Groundwater levels in built-up areas fell by 1.87 meters during the pre-monsoon and 1.92 meters during the post-monsoon period over the decade. In contrast, groundwater levels in dense vegetation areas decrease\d by only 0.05 meters in pre-monsoon and 0.09 meters in post-monsoon period. Additionally, in Jhang District, significant groundwater drawdown was observed across Bare Land, Built-up Areas, and Dense Vegetation categories over the same period.
From 2013 to 2023 in Chaj Doab, groundwater levels decreased by 0.80 meters with an increase in evapotranspiration from 6.88 mm/day to 7.03 mm/day. During Post-monsoon season, groundwater levels dropped by 0.81 meters, while evapotranspiration increased from 4.66 mm/day to 4.95 mm/day. This increase in ET indicates higher water demand and potential evaporation losses, indicating groundwater depletion.
Objectives of this research1.To investigate the spatiotemporal variations of Land Use and its impact on groundwater in Chaj Doab.
2.Assessing climate-induced changes in evapotranspiration and their impact on groundwater Changes.
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Results and Discussions
The significant increase in built-up areas and decrease in dense vegetation in Chaj Doab from 2013 to 2023 has severely impacted groundwater recharge, as urbanization reduces the natural absorption capacity of the land. This shift, rising evapotranspiration (ET) rates due to climate change, indicates groundwater depletion. A comparison of these findings with other studies employing GIS methodologies revealed consistent global trends. For instance, research In Piedmont Region of North Carolina, USA, (2000-2015), leading to groundwater level drops of 0.6 to 1.8 meters and elevated evapotranspiration due to increased impervious surfaces. Similarly, Upper Guadiana Basin, Spain (1990-2010), agricultural expansion and urbanization contributed to a decrease in groundwater recharge, with GWL falling by 1.0 to 2.0 meters and a rise in evapotranspiration rates indicating higher water demand. All reported similar patterns of urbanization, leading to reduced groundwater recharge and increased ET rates.
Conclua
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