CGWB - Publications and Media Warehouse
Category | Aquifer Mapping |
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State | Uttarakhand |
District | Dehradun |
Block | Chakrata Doiwala Kalsi Raipur Sahaspur Vikasnagar |
Year of Issue | 2022 |
Number of Authors | 2 |
Name of Authors | MS. CHANDREYEE DE, MS. ANJALI KUSHWAHA |
Keywords | Introduction, Data Collection and Generation, Data Interpretation, Integration and Aquifer Mapping, Ground Water Resources, Ground Water Related Issues and Management Strategies, Block-wise Ground Water Management Plans |
File | Download |
The study area (Dehradun District) is situated in NW corner of Uttarakhand State and extends from Latitude 29° 58‘N to 31° 02‘30" N and Longitude 77° 34’45’’ E to 78° 18’30’’ E. The study area has been taken up for aquifer mapping study in AAP 2020-21. The total area of Dehradun district is 3088 km2 with an average altitude of 640 m above MSL. The present study area comprises of parts of Dehradun district covering an area of 2138.00 sq. km. NAQUIM studies have been carried out in the Doiwala block (1000 sq.km), Raipur Block (393.13 sq. km), Vikasnagar block (224.26 sq. km) and Sahaspur block (520.61 sq.km). The remaining blocks have slope greater than 20% and hence have not been included in the scope of NAQUIM studies. The study area receives an average annual rainfall of 2051.4 mm. Most of the rainfall is received during the period from June to September; July and August being the wettest months of the year. The study area may be divided into four geomorphological units namely alluvium, piedmont fan deposits, structural and denudational hills and residual hills. Dehradun is one of the largest intermontane valleys between the Mussoorie Ranges of the Lesser Himalaya to the north and the Siwalik Ranges to the south. The study area is bounded by major faults from all sides; the Main Boundary Thrust (MBT) to its north, the Himalayan Frontal Thrust (HFT) to its south, the Yamuna Tear Fault (YTF) to the west, and the Ganga Tear Fault (GTF) to the east, making it a structurally isolated block. Alluvial fans, hillocks, river terraces, and floodplains are the major geomorphic units in this region, and the valley fills have been described as Dun gravels‘. Geologically whole Doon valley can be divided into three regions of Lesser Himalaya, the Siwalik group and the Doon Gravels. Canals and tube wells are main means for the irrigation in the study area. The area, irrigated by Canal is 13181 ha which contributes to 54 % of the total irrigated area. Ground water contributes to 10 % of total irrigated area. The two rivers Ganga and the Yamuna form the major drainage of the NAQUIM area and are effluent in nature. The general flow direction of groundwater is NW- SE in the eastern part of the study area and NE- SW in the western part of the study area. 3 The Central Ground Water Board, Dehradun constructed four gabion structures on Medawala Khala in Thano Forest Range. It is observed that the Doon Gravels are highly receptive to the artificially recharged water. There are 44 Number of NHS monitoring stations in the study area, which are being regularly monitored for ground water level and quality. To attempt the hydrogeological interpretation of aquifer disposition and its nature within the study area, the data from 12 Nos. of CGWB Exploratory Wells have been analyzed in detail. Doon Gravels are highly porous and they have a significant permeability and act as good groundwater reservoirs. Groundwater occurs under unconfined and semi-confined conditions. The saturated granular zones occur in a depth range between 35.50 and 138.68 m bgl. The shallow aquifers occur under unconfined conditions, while deeper aquifers occur under semi-confined to confined state of disposition. The confining layers are impermeable clay beds. To know the water level and its behaviour with respect to time and space, 44 NHS monitoring wells comprising of Piezometers, dug wells and Handpumps were analysed. 97% wells show rise in depth to water level during post-monsoon. The seasonal fluctuation (rise) in the district varies from 0.035 to 6.93 metres. Long term water level trends from the existing 29 nos. of hydrograph stations were statistically analyzed (2010-19). It is observed that the long-term water level trends during pre and post-monsoon seasons are rising. Rising trend of water level suggests that surface water irrigation not only compensates the withdrawal but puts additional recharge through return flow in the system and through direct seepage from running canal. For estimation of the quality of ground water, ground water samples from the 44 locations of NHS monitoring stations have been collected during pre-monsoon 2020. The ground water samples were analysed for major chemical constituents at Chemical Laboratory, CGWB, NR, Lucknow. The general chemical quality reveals that most of the wells contain low dissolved mineral contents and hence, groundwater in Dehradun district is fresh and potable. All the blocks of Dehradun District fall under the Safe Category with an average of 21.77% Stage of GW Extraction for the entire district. Based upon the climatic conditions, topography, hydro-geology of the area, suitable structure for rain water harvesting and artificial recharge to ground water need to be planned and implemented. Farm ponds, chalkhal, efficient irrigation practices like drip irrigation and sprinklers can help in water conservation. 4 Dehradun district is growing day by day as an Industrial City having clusters of Industries. Each industry is having very large roof area. Therefore, industries may be directed to harvest the roof top rain water by constructing recharge structures in their premises as the area receives plenty of rainfall.