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Title: Hydrogeological Modeling for Spatio-Temporal Assessment of Groundwater Fluctuation and Quality: A Case Study in Lower Chenab Canal, Pakistan
Authors: Awais, Muhammad
Keywords: Engineering & Technology
Issue Date: 2019
Publisher: University of Agriculture, Faisalabad.
Abstract: Groundwater is imperative for global food production, lifeline for all types of agriculture, cultures associated with it and inhabitants around the globe. In Pakistan, irrigation water supplies for 40-60% area are met through groundwater resources depending upon rainfall variability. The 70 percent farming community of the province Punjab, Pakistan fulfill their crop water demands either directly or indirectly from groundwater. Resultantly, the aquifer has depleted and deterioration in groundwater quality is observed due to upcoming of saline water. A detailed investigation was carried out to address the aforementioned issues in Lower Chenab Canal (LCC-E) command area of Punjab, Pakistan. The field data from 2005-2013 were utilized for the analysis of prevailing groundwater levels and GIS mapping was used to study the groundwater quality patterns. The field data from 2005-2013 of water levels and quality patterns were analyzed and mapped by employing GIS. A three dimensional groundwater flow model employing USGS developed code MODFLOW-2005 was used for existing and future predictions of groundwater levels up to 2033, and MT3DMS transport model was utilized for groundwater quality assessment. The model was calibrated manually for the steady state initially; the groundwater levels for the year 2006 were used as the initial conditions and hydraulic conductivity values were adjusted to have a close agreement between observed and simulated heads. The Parameter estimation tool acronym as ‘PEST’ was utilized for transient state calibration of the model. The transient state calibration was done for the years-2006-2011. The calibrated model was validated with a different data set for the years 2011-2013. To predict the model results and to simulate the future response of the aquifer under changed recharge and pumping, a number of future scenarios were developed. The hydrodynamics of the groundwater flow were studied for two decades i.e. up to year 2033. The results of the future predictions of groundwater levels under Scenario-I, which represent the business as usual conditions, showed that there was a net gain of water levels in upper parts of the study area and lowering of water levels in central and lower parts. A maximum of 5.17m decline and 5m increase in water levels was anticipated in LCC. The percentage of good quality area decreased slightly with 1% change from 2013, whereas 2.5% decrease in area under marginal category was observed while area under unsuitable quality groundwater was expected to be increased from 24.8% to 28.6% in LCC. The predicted results of Scenario-II with increased pumping following historical trends showed an overall decline in the complete LCC. Maximum drawdown is anticipated in Bhagat Sub Division which shows up to 15.68m decline. The area under good quality water will also be significantly dropped from 49% to only 7%. The area under marginal category will have a boom from 41% to 55%, whereas the area under unsuitable category will also be increased manifold from 10% to 38%. The piezometric water levels for the spatially adjusted recharge and discharge patterns under the future scenario-III revealed an overall decline in water levels in the upper four sub divisions, whereas an overall recovery in the water levels was observed in lower five subdivisions of the study area where irrigation recharge was allowed to increase. The area under good quality water which was pre -dominantly in the upper subdivisions have shrinked significantly from 49% to 19%, area under marginal quality groundwater has increased manifold from 41% to 57%. Similar kind of trends were observed in unsuitable category groundwater which has increased enormously from 10% to 24%. The simulation under H3B2 future climate change scenario showed some interesting results. The declining water level trends in all the subdivisions were observed. Tarkhani Sub Division is expected to have maximum dropdown of 4.77m. Minimum drop down in water level was anticipated for Sultanpur subdivision i.e. 0.51m. The predicted results for water quality status shown degraded water quality status in the entire LCC. Only 19.7% area would sustain its status of having good quality of water, 49.3% area will have marginal quality of groundwater whereas 31% area would be converted to unsuitable quality of groundwater in the LCC.
Gov't Doc #: 18776
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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