Role of forests in springshed recharge
In the Himalayan region, most of the water consumed comes from springs . About 15% of Indian population, more than 20 crore people, depend on springs for their source of fresh water .
Springs are places where groundwater flows out to the surface from an aquifer. This can happen in mountainous regions when the water table is higher than the mouth of the spring, as happens in artesian wells shown in the figure below.
Non-artesian springs are even more common in the Himalayas. These are simply underground streams that flow from a higher elevation through the earth to a lower elevation and exit in the form of a spring, using the ground like a drainage pipe.
A springshed is the entire water catchment area of the aquifer feeding the spring.
Springs, though specialized and common in mountainous regions, are nevertheless a fragile resource, owing to the usually limited size of the underlying aquifer, and limited opportunities for springshed recharge due to high run-off in the mountains.
In the Himalayan villages, springs as a source of fresh water are being increasingly threatened by three kinds of pressures, all of which can trace their origins to climate change :
- Rise in rainfall intensity resulting in increased rate of runoff and reduced springshed recharge per unit of rainfall
- Reduction in temporal spread of the rainfall leading to decreased springshed recharge
- Marked decline in winter rain resulting in immense depleting pressure on the aquifers
These factors have resulted in many perennial springs turning into seasonal ones, and many seasonal ones drying out completely [2, 3].
Forest conservation and management in the springsheds can have a transformative effect on recharge of the aquifers. Forests arrest runoff, and hold water, allowing slow seepage and recharge of aquifers. Forests also vastly increase the springshed area, collecting and directing water through streams and channels.
Accurate identification of catchment area, and targeted forestry is one of the most effective ways of springshed recharge. The Jal Jeevan Mission of the Government of India has taken up identification and documentation of springs and springsheds all over the country on a grand scale. A centralised National Spring Information System (NSIS) has been created to record co-ordinates, slope characteristics, land use and land cover, vegetation, soil type, rock type, rainfall, spring discharge, water quality, and water demand and availability for all of the major springs throughout the country . Such detailed socio-economic and hydro-geological mapping of springs would give complete information to decision makers to plan springshed management and associated forestry needs.
Forestry as an effective method of springshed recharge has been well tested and documented. For example, undertaking afforestation in the Luhali village in Tehri district in Uttarakhand, by planting 500 fodder plants and 10,000 napier grass saplings, increased the spring discharge from 70 litres per minute to more than 260 litres per minute, an increase of more than 3.5 times within two years . Similar interventions in the Chureddhar village in the same district increased the spring discharge from 9 litres per minute to 14 litres per minute within a decade [3, 4].
The Jal Jeevan Mission has also placed emphasis on afforestration as a primary way of springshed revitalisation. As per the guidelines of the Jal Jeevan Mission, restoration and strengthening of springs should be done through the Compensatory Afforestation Fund Management and Planning Authority (CAMPA) .
Thus, forestry as an effective way of springshed recharge is well known and understood. However, it needs to be applied and implemented in even greater scale and numbers. The centralised database of the National Spring Information System will play an invaluable role in enabling effective and efficient interventions for springshed recharge management.