After reading this article you will learn about the advantages and methods of artificial recharge of ground water.
Advantages of Artificial Recharge of Ground Water:
Following are the main advantages of artificially recharging the ground water aquifers:
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.
Methods of Artificial Recharge of Ground Water:
The methods of artificial recharge can be broadly classified as:
1. Spreading Method:
i. Spreading within channel
ii. Spreading stream water through a network of ditches and furrows
iii. Ponding over large area:
(a) Along stream channel viz., Check Dams/Nala Bunds
(b) Vast open terrain of a drainage basin viz., Percolation Tanks
(c) Modification of village tanks as recharge structures.
2. Recharge Shafts:
i. Vertical Shafts
ii. Lateral Shafts
3. Injection Wells:
4. Induced Recharge:
5. Improved Land and Watershed Management:
I. Contour Bunding
II. Contour Trenching
III. Bench Terracing
IV. Gully Plugging
In alluvial as well as hard rock areas, there are thousands of dug wells, which have either gone dry, or the water levels have declined considerably.
These dug wells can be used as structures to recharge the ground water reservoir. Storm water, tank water, canal water etc. can be diverted into these structures to directly recharge the dried aquifer. By doing so the soil moisture losses during the normal process of artificial recharge, are reduced.
The recharge water is guided through a pipe to the bottom of well, below the water level to avoid scouring of bottom and entrapment of air bubbles in the aquifer. The quality of source water including the silt content should be such that the quality of ground water reservoir is not deteriorated.
Schematic diagrams of dug well recharge are given in Fig. 27.6:
In urban and rural areas, the roof top rainwater can be conserved and used for recharge of ground water. This approach requires connecting the outlet pipe from rooftop to divert the water to either existing wells/tube wells/bore wells or specially designed wells. The urban housing complexes or institutional buildings having large roof areas can be utilised for harvesting roof top rainwater for recharge purposes.