CONCLUSIONS & RECOMMENDATIONS: –

Based on spot levels obtained from google image and GPS data recorded in the field, the localized physiographic gradient is determined which is in general towards south with elevation ranging from 247 m to 256 m from mean sea level. The area has good vegetation with deep-rooted plants. In the studied area, Nabha block is occupied by Indo-Gangetic alluvial plain of quaternary age, and falls in Ghaggar basin. The rainfall runoff is generated through various minor natural drains. The canal network for irrigation also exists in the area from river Ghaggar. The average rainfall of last 6 years is reported as 441.58 mm/annum as per IMD. The ground water occurs in alluvium consisting of Fine, Medium and Coarse-grained sand, which forms the potential aquifers. In the shallow aquifer (up to 50m) ground water occurs under unconfined/water table conditions; whereas, in deeper aquifer, semi-confined/confined conditions exist. The water level in the studied area ranges between 25.98 m to 32.13 m below ground level in pre monsoon season based on hydrogeological observations. The seasonal fluctuation is minimum 0.3 m and maximum 3.6 m as per CGWB district brochure. Based on the samples drawn from tube wells of GSK Plant, Nabha and its 5 km radius area reveals that most of wells show total dissolved solids below 1000 mg/ltr. Therefore, water is largely under fresh category. As per chemical analysis report of water from existing tube well in the plant premises, the most of the gradients are within permissible limits as per IS10500:2012. However, water may be suitably treated for specific industrial use. The water yield from tube wells varies between 64.8 m3/day to 575 m3/day as revealed by hydro geological well inventory in plant and its 5 km radius area. The wells within depth up to 60 m have low yields up to 125m3/day, whereas, the tube wells up to 200 m depth yield as high as 575m3/day. Ground water flows from north towards south, south-east and south-west as shown in water level contour map. The average Hydraulic Gradient as per water level contour map is 1/426. The existing five rainwater-harvesting structures with injection wells serve the purpose of recharge to ground water from rooftop area runoff and natural recharge from of the green area. Total recharge to ground water to be captured within the GSK plant premises is 6,854.44 m3 /annum (Through rooftop rainwater harvesting 4,562.73 m3 /annum & through open/green area 2,288.72 m3 /annum). Eight rain water ponds have been selected in various villages of Nabha Block outside plant premises to meet 200 % recharge of the present ground water extraction by the GSK plant besides plant premises. The catchment area of ponds is demarcated with the help of spot levels, contours and physiography as shown in Fig. These ponds have been found feasible for recharge of excess runoff during rains by increasing depth in all selected ponds and making percolation pits in one pond for additional ground water recharge. The recharge potential created outside plant premises would be 6,79,450.44 m3 /annum. The Total recharge measures to be created inside and outside the plant premises would be 6,86,301.88 m3 /annum equivalent to 1880 m3 /day as against required 200 % recharge to the tune of 6,80,360 m3 /annum.

The storage capacity of selected 8 ponds for additional recharge would be created by increasing the depth of each pond. In addition to increase in depth up to 3.5 m in pond-2 (Village-Lubana Teku), five percolation pits evenly distributed at a spacing of more than 30 m may also be installed & in pond-4 (Village-Kot Kalan), two percolation pits evenly distributed at a spacing of more than 20 m may also be installed. The dimensional parameter of percolation pit may be kept as 1 m (length) x 1 m (width) x 2 m (depth) with 6” dia injection well of 50 m depth capable of recharging 181 m3 /day of rainwater as per recharge test. The inlet of the structure should be 1 m above pond bed as dead storage for use by villagers. The quarterly cleaning/ removal of silt from the pond beds is suggested for efficient working of RWH system. The section view of proposed percolation pits with injection wells to be installed in pond-2. All the rainwater ponds in 8 villages as described above may be protected by fencing and deployment of security person/agency to avoid contamination and possible human/cattle accidental hazards. For good design of piezometer, a borehole of 14”diameter should be drilled up to 18 m depth by Drilling machine in the project premise with 8” plain pipes The pipe of the bore well should be left 1 m above the ground level & concrete structure may be made around this pipe with 14 inch thickness to prevent the bore well from surface pollutants around the bore well. Chamber of 14” diameter may be made with well cap having lock & key arrangement. There should be provision of 2” dia PVC airline in the borewell for inserting probe of manual / automatic water level recorder for complete precision in measurement of the water level data. Schematic design of piezometer is given in Fig.