The rain-fed regions of India are characterised by aberrant behaviour of monsoon rainfall, eroded and degraded soils with multiple nutrient as well as water deficiencies, declining groundwater table and poor resource base of the farmers. These are the major constraints for low and unstable yields. In addition, climate variability, including extreme weather events, poses serious threat to rain-fed agriculture. Rainwater harvesting is a panacea for the constraints of rain-fed farming.
Agricultural production in semi-arid, backward districts (Panchmahal and Dahod) of Gujarat are low due to rainfall dependence, less green water (in-situ) and blue water (runoff) use; poor recharge capacity of aquifers, lesser groundwater availability and absence of irrigation facilities. In this region, few farmers are having dug wells but due to poor water holding capacity of the aquifers they are not able to get sufficient water to irrigate their crops during post monsoon season.
Several blue water use options such as check dams, recharge structures, ponds had been constructed by some agencies at different locations. However, adoptability of these techniques by individual farmers in this region is very low due to higher cost of construction, which varies between Rs.2-4 lakhs for check dams/ recharge structures. Several masonry check dams constructed in many arid and semi-arid regions have also failed within few years after construction due to improper material of construction, faulty execution, inadequate curing, and so on. Further, trained manpower is also not usually available for construction of check dams and recharge structures due to remoteness or inaccessible locations and also as possibility of getting more lucrative options at building construction sites in urban areas. This emphasizes the need to develop cost effective and easily adoptable water harvesting techniques/structures in rain-fed regions.
In view of the above mentioned challenges, a project was initiated at farmers’ fields by ICAR-Indian Institute of Soil and Water Conservation Research Centre (ISWCRC), Vasad, Gujarat under Arid and Semi Arid Region (ASAR) programme of Science for Equity, Empowerment and Development (SEED) Division, Department of Science and Technology (DST), for efficient in-situ (green water) and ex-situ (blue water) water harvesting techniques to improve farm productivity.
Green water harvesting techniques
A cost effective and adoptable green water use techniques, such as paired row and furrow, conservation furrow and stubble mulch farming, vegetative filter strips, V shape micro catchment, crescent shaped bunds, saucer shaped basins and crop residue and gravel mulch techniques and furrow irrigation techniques for limited water supply conditions, for rain-fed crops for rabi crops were evaluated and demonstrated in farmers’ fields of Navadh, Navagam and Revaliya villages in Panchmahal District of Gujarat. Over 90 percent of the population in these villages, belong to Scheduled Tribe community and their main occupation is farming.
Blue water harvesting techniques
The blue water harvesting techniques of cost effective and innovative check dams: i) Plastic check dam, (masonry head-wall replaced with poly propylene sheets supported by GI angular frame) and ii) HDPE film embedded stone check dams have been developed and evaluated for rainwater harvesting in rain-fed regions. Direct well recharge filters (with vertical and horizontal flow) were evaluated and demonstrated in farmers’ fields for enhancing groundwater availability in this region.
Skill enhancement of the local farmers
As a part of skill development activities, several field demonstrations, visits and training programmes covering various green water harvesting techniques were conducted. Over 600 farmers and 150 students from the selected villages were trained to adopt and implement these techniques and 70 farmers are currently practicing these techniques in their fields.
The demonstration activity was found to have significant impact on the crop productivity. The green water harvesting techniques for rain-fed crops produced maximum green water harvesting (up to 80%) and minimum runoff and soil loss. It also enhanced the crop yields of rain-fed crops up to 30 per cent. Alternate furrow with surge flow irrigation is better option as this method saved the irrigation water up to 70% without affecting the crop growth and yields. The saved irrigation water can bring additional area under cultivation and increases the production by up to 1.5 times.
Cost effective and innovative check dams designed, developed and deployed by ICAR-ICWCRC are easy to construct and reduce the cost to one-fourth as compared to conventional check dams while using minimal manpower. These pre-fabricated check dams can also be easily transported and constructed in difficult terrain/ locations and can store up to 8000-15,000m3/structure of rainwater. These check dams and recharge filters will not only decrease the cost/unit of water stored (up to 1/4th) but also increase the rainwater availability, ground water recharge (up to 5 times) and enhance the productivity and production in rain-fed regions by up to two folds.
These innovative check dams can be up-scaled and adopted through line agencies and NGOs for sustainable development in the rain-fed area and thus offer better livelihood opportunities to the farmers.