www.iasinsights.in ; www.iasgyaan.com posts Hindu summary-30th June 2018 about Handling water scarcity by recharging aquifers.
Recharging aquifers-a solution to water scarcity
Focus on groundwater recharge to curb water scarcity
Facts to be known:
- 90 per cent of the rural water supply, over 50 per cent of the urban water supply, and over 70 per cent of the agricultural water supply is sourced from aquifers
- India is the highest user of groundwater, even ahead of the US and China, consuming over 70 percent of groundwater.
- Agriculture consumes more than 70 per cent of groundwater, this sector needs special attention
Creating water scarcity.
- water over-exploitation is linked with the geometrical increase in population.
- rapid urbanization
- Change in life styles and consumption patterns
Scarcity in rural areas reasons:
- Ponds dried up or have been “converted” into wastewater collection pits, rendering them not only useless, but also as a breeding ground for diseases.
- Farming water-intensive crops as they are remunerative.
- India exporting water(through water intensive crops)
- Mass tailored solutions
- Providing ready and cheap supply of water due to agriculture subsidies.
In Industrial areas:
- Water usage is organised and productive, which means that it has an inherent potential to produce, recycle, and reuse its own water without loading the environment.
- Some industries located in water sufficient areas use high ground water, contaminating of water and soil as well.
Why water scarcity is Geometrical?
Step 1 : As we keep exploiting water resources, the need for a proportional recharge of the aquifer stands.
Step 2: depletion is bound to get worse fast if not recharged.
Step 3: As the depletion of aquifers occurs, the dry zone created above the water table deepens in direct proportion.
How aquifer recharges?
- The earth’s crust comprises of layers of soil particles.
- When it rains, the top layers of soil are saturated with water, expelling air from the voids between the particles.
- If the water supply is continuously available, water will be transmitted to the underlying layers, saturating them too.
- However for this, the water supply has to be consistently available over a reasonably sustained period, in the absence of which the post-rain glare of the sun will dry the upper layers of the soil, resulting in water from the lower layers traveling to the upper layers via capillary action.
- This results in the subsequent drying up of underlying layers, so the aquifer does not get recharged and remains depleted.
- Rainfalls (especially in semiarid regions) are becoming intense and short-spanned, causing the problem of recharging aquifers to worsen due to huge runoff (no recharge is possible due to low retention of rainwater on the soil and the resulting low rate of percolation).
- Need to replace the “layer-by-layer saturation” for recharging the aquifer with a more sustained method: recharge through rainwater harvesting. This can be done easily by constructing recharge shafts/wells within geographic proximities in order to benefit the water levels locally, through harvesting, collecting, and recharging.
- Must minimize water drainage and direct water to the aquifer as soon as possible (especially in areas where there is less or no contamination of water).
- In urban areas, where land is scarce and precious, parks can be constructed a level below the ground or road level to allow the direct drainage of rainwater into a constructed aquifer recharge system.
Cost-effective, timely, and sustained implementation of such solutions to recharge the aquifer directly are needed.