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Title: Temporal and Spatial Variation of Groundwater Recharge in Chaj Doab Pakistan Using Remote Sensing and Modeling Approach
Authors: Aslam, Muhammad
Keywords: Engineering & Technology
Engineering & Technology
Issue Date: 2022
Publisher: University of Agriculture, Faisalabad
Abstract: Groundwater plays a key role for the raising of agriculture crops, meeting the domestic and industrial needs. In past few decades’ burden on the groundwater resources of the country has been increased due to unchecked and unguided exploitation of it. Management of the groundwater resources has become necessary for its sustainable future use. For management of groundwater resources this research was carried out in selected area of Chaj doab Pakistan, in order to determine spatial and temporal variation of groundwater recharge and fluctuation in water level. Groundwater recharge model (WetSpass) and groundwater flow model (MODFLOW) were coupled to assess the current stage and future conditions of the aquifer. For spatial and temporal estimation of groundwater recharge a monthly water balance model (water and energy transfer among soil, plants, and atmosphere) WetSpass-M was used to determine the groundwater balance components on annual, seasonal, and monthly time scales for a period of last 20 years (2000-2019). The spatial distribution of water balance components depends on soil texture, land use, groundwater level, slope, and meteorological conditions. Inputs for the model included data of topography, slope, soil, groundwater depth, slope, land-use, and meteorological data (e.g. precipitation, air temperature, potential evapotranspiration, and wind speed) which were prepared using ArcGIS in asci file format. Model was validated against the observed groundwater level fluctuation. The long-term average annual rainfall (455.7 mm) was distributed into 231 mm (51%) as evapotranspiration, 109.1 mm (24%) as surface runoff, and 115.6 mm (25%) as groundwater recharge. Seasonally water balance components were divided into two seasons (summer and winter). The long-term annual groundwater recharge resulted that its value for the period of 2000 to 2019 ranged between 99.1 mm/year to 218.5 mm/year with an average value of 115.6 mm/year. Long-term summer recharge ranged 80.4 mm/season to 168.3 mm/season and long-term winter recharge ranged from 18.5 mm/season to 20.5 mm/season. Long-term monthly groundwater recharge ranged between 8.3 mm/month to 18.2 mm/month as minimum and maximum values, respectively. The WetSpass-M model's findings were used to develop a regional groundwater model for simulation of different aquifer management scenarios in the study are of Khadir Chaj doab, Pakistan. A distributed groundwater flow model; MODFLOW-2005 was developed to study the future scenarios of groundwater level in study area. The model was calibrated manually at steady state condition against the observed groundwater table data from 2003 to 2019. Groundwater level of year 2003 was taken as initial condition for steady state model and was calibrated against the observation wells data of year 2003-2014 at transient state conditions. It was validated at data of 2015-2019. In this study three main scenarios were simulated for future prediction of the groundwater. Scenario-I (to assess the impacts of pumping if the prevailing conditions of the years 2003 to 2019 will be continued until 2035); Scenario-II (Impact of pumping on aquifer by increasing the pumping capacity from 25%, 50%, 75% and 100% for upcoming 10 years) and Scenario-III (Impact upon the aquifer by decreasing in average groundwater recharge from river and rainfall by 50% by following the same pumping trend). Scenario-I results showed that there would be 18.1m decline in groundwater table at the end of year 2035. Scenario-II results predicted that decline in water by increasing the pumping capacity by 25%, 50%, 75% and 100% there would be decline in water table by 2.0, 5.5, 9.8 and 14.3m respectively in the year 2029. Result of Scenario-III showed that by decreasing the recharge from rainfall there would be 0.7m decline in water table and by open water bodies there would be 2.4m decline in water table. Spatially more decline in water table was observed in the areas away from the river. These results are very helpful to determine the recharge and discharge potential of the aquifer for its management.
Gov't Doc #: 27371
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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