Artificial recharge
- 1. ABY M MUNDACKAL Email – abymichael@gmail.com Ph +91 9496480150
- 2. INTRODUCTION IMPORTANCE OF ARTIFICAL RECHARGE METHODS OF ARTIFICAL RECHARGE ADVANTAGES AND DISADVANTAGES CONCLUTION REFERENCES
- 3. GROUND WATER- Water present in the subsurface in a specific area during a specific period of time. Subsurface water or ground water is fresh water locate in the pore space of soils and rocks. ARTIFICAL RECHARGE- Augmenting the natural infiltration of precipitation or surface water into underground formation by some methods. (Source: India water week 2012, Article, Ground water management- Artificial Recharge of round water,)
- 4. Ground Water Depletion Ground Water Pollution Drinking Water Shortage in Urban Areas Seawater Ingress in Coastal Aquifers (Source: Manual on artificial recharge of ground water, Gov. of India)
- 5. Quantity of source water available Quality of source water available Resultant water quality (after reactions with native water and aquifer materials) Clogging potential Underground storage space available Depth to underground storage space Transmission characteristics of the aquifer Applicable methods (injection or infiltration) Legal / institutional constraints Costs Cultural / social considerations
- 6. These can be broadly classified as: Spreading Method Spreading within channel Spreading stream water through a network of ditches and furrows Ponding over large area Along stream channel viz. Check Dams/ Nala Bunds Vast open terrain of a drainage basin viz. Percolation Tanks Modification of village tanks as recharge structures. Cont…
- 7. Recharge Shafts Vertical Shafts Lateral Shafts Injection Wells Induced Recharge Improved Land and Watershed Management Contour Bunding Contour Trenching Bench Terracing Gully Plugging
- 8. Constructing small ‘L’ shaped bunds within a stream channel so that water moves along a longer path thereby improving natural recharge Useful where a small flowing channel flows through a relatively wide valley. Not useful where rivers/ streams are prone to flash floods and the bunds (levees) may be destroyed.
- 9. Generally three patterns of ditch and furrow systems are adopted: 1) With a “zigzag” course following the contours and land slopes 2) With branches from a main channel 3) With ditches arranged perpendicular to the main channel.
- 11. (i) Although this method is adaptable to irregular terrain, the water contact area seldom exceeds 10 percent of the total recharge area. (ii) Ditches should have slope to maintain flow velocity and minimum deposition of sediments. (iii) Ditches should be shallow, flat-bottomed, and closely spaced to obtain maximum water contact area. Width of 0.3 to 1.8 m is typical. (iv) A collecting ditch to convey the excess water back to the mainstream channel should be provided.
- 13. These are the most prevalent structures in India to recharge the ground water reservoir both in alluvial as well as hard rock formations. The efficacy and feasibility of these structures is more in hard rock formation where the rocks are highlyfractured and weathered. In the States of Maharashtra, Andhra Pradesh, Madhya Pradesh,Karnataka and Gujarat, the percolation tanks have been constructed in basaltic lava flows and crystalline rocks.
- 15. The existing village tanks, which are often silted up or damaged, can be modified to serve as recharge structure Some of the tanks in Maharashtra and Karnataka have been converted.
- 17. Ideally suited for deep water levels (up to 15 m bgl). Presence of clay is encountered within 15 m. Effective in the areas of less vertical natural recharge. Copious water available can be effectively recharged. Effective with silt water also (using inverted filter consisting of layers of sand, gravel and boulder). Depth and diameter depends upon the depth of aquifer and volume of water to be recharged. The rate of recharge depends on the aquifer material and silt content in the water. The rate of recharge with inverted filter ranges from 7-14 lps for 2-3 m diameter.
- 19. Ideally suitable for very deep water level (more than 15 m) Aquifer is overlain by impervious thick clay beds Injection well can be with or without assembly The injection well with assembly should have screen in the potential aquifer at least 3 -5 m below the water level The injection well without assembly is filled with gravel to provide hydraulic continuity so that water is directly recharged into the aquifer The injection well without assembly is very cost effective Depending upon volume of water to be injected, number of injection wells, can be increased to enhance the recharge rate The efficiency is very high and rate of recharge goes even up to 15 lps at certain places
- 21. Ideally suited for areas where permeable sandy horizon is within 3 m below ground level and continues upto the water level – under unconfined conditions Copious water available can be easily recharged due to large storage and recharge potential Silt water can be easily recharged 2 to 3 m wide and 2 to 3 m deep trench is excavated, length of which depends on the volume of water to be handled With and without injection well
- 23. Hydraulically, the effectiveness of induction of water in injection well is determined by: Pumping rate Permeability of aquifer Distance from stream Natural ground water gradient Type of well
- 29. 1. No large storage structures needed to store water. Structures required are small and cost-effective 2. Enhance the dependable yield of wells and hand pumps 3. Negligible losses as compared to losses in surface storages 4. Improved water quality due to dilution of harmful chemicals/ salts 5. No adverse effects like inundation of large surface areas and loss of crops 6. No displacement of local population 7. Reduction in cost of energy for lifting water especially where rise in ground water level is substantial 8. Utilizes the surplus surface runoff which otherwise drains off
- 30. 9. The technology is sound and generally well understood, both by technicians and the general population. 10. Very little special equipment is needed to construct drainage wells. 11. In rock formations with high structural integrity, few additional materials may be needed to construct the wells. 12. Groundwater recharge stores water during the wet season for use in the dry season, when demand is highest 13. Aquifer water can be improved by recharging with high-quality injected water. 14. Recharge can increase the sustainable water yield of an aquifer significantly.
- 31. 15. Recharge methods are environmentally attractive, particularly in arid region. 16. Most aquifer recharge systems are easy to operate. 17. In many river basins, controlling surface water runoff to provide aquifer recharge reduces sedimentation problems 18. Recharge with less saline surface water or treated effluents often improves the quality of saline aquifers, facilitating use of their water for agriculture and livestock. 19. Aquifer may be used for the storage and distribution of water and for removing contaminants by natural cleaning processes that take place as polluted rain and surface water infiltrate the soil and percolate down through the various geological formations.
- 32. 1. In the absence of financial incentives, laws or other regulations to encourage land owners to maintain drainage wells, they may fall into disrepair and ultimately become source of groundwater contamination. 2. There is potential for contamination of the groundwater from injected surface runoff water, especially from agricultural fields and road surfaces. In most cases, surface runoff water is not pre-treated before injection. 3. Recharge can degrade the aquifer unless quality control of the injected water is adequate. 4. Groundwater recharge may not be economically feasible unless, significant volumes can be injected into the aquifer. 5. A very full knowledge of the hydrogeology of an aquifer is required before any full scale recharge project is implemented 6. Disturbances of soil and vegetation cover during the construction of water traps may cause environmental damage to the project area.
- 33. Ground water resources plays a major role in ensuring livelihood and security across the world, specially in economies that depend on agriculture. India is now the biggest user of ground water for agriculture in the world. So following are the recommendations 1. Laws regarding judicious use of water should be formulated. 2. More and more areas be covered under artificial recharging and promoting it by giving subsidies wherever necessary 3. Awareness creation programmers should be developed and promoted 4. Affordable and viable technologies for ground water recharging need to be developed
- 34. Manual on artificial recharge of Ground water 2007 September, Center Ground water board , Govt. of India. Articles on Artificial Ground water recharge with special reference to India by M/s Amartya Kumar Bhattacharya, Associated professor, Bengal Engineering and science University, Shibpur. Irrigation and water power engineering, Dr BC Punmia, Laxmi Publication Pvt. Ltd. New Delhi. Article on Ground water management- Artificial recharge of ground water, Er Kirit B. Trivedi, Deputy EE, Govt of Gujarat.
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