Harvesting and Managing Rainwater

PRADAN has been working on developing in-situ rainwater harvesting techniques since 1990s because a large segment of poor people in villages are small and marginal farmers with no access to irrigation and rainfall is unreliable and much of it runs off. Different low cost techniques have been tried to suit local contexts. Of these, two techniques, the 30x40 model and the 5% model became popular among farmers. The former, comprising of dividing gently sloping un-terraced land into contiguous parcels of 30’x40’, each with shallow bunds and a water storage pit at the lowest corner was tried for treating wastelands. The latter consists of making a 2-3 meter deep pit at the upper corner of each terraced paddy field on 5% area of the field across a large (10 hectare or more) landscape in a gently sloping terrain.

The 5% model was conceived to protect rain-fed paddy in Jharkhand from dry spells during September, known as Hathiya locally. The core idea is that every plot should have a water body to hold back rainwater that would otherwise flow out as run-off during heavy showers. It captures excess water when it rains and releasing it to the field during dry spells. The pits enhance sub-surface water flow and improve the moisture regime of the whole area. Additionally, the water in the pits is used to irrigate in times of scarcity during the crop’s vegetative growth phase.

 

Impressed by the potential of the 5% technique, the community in many districts is building larger structures covering about 10-15% area as seepage tanks. A larger water body would strengthen livelihoods in several ways and make the idea more easily replicable. It would insure the monsoon paddy against intermittent dry spells. Farmers would also be able to use the harvested water to take an early winter crop following paddy in case of late monsoon rains. Finally, a larger water body would make it feasible to rear fish on a small scale. Field bunds using the soil dug out of the 5% pits, gully plugs in erosion-prone portions of the landscape and large diameter dug wells in the valleys for lift irrigation are the other techniques that have been tried successfully. The underlying principle is that in an undulating terrain, used largely for farming and underlain with an impervious substrate, rainwater must be harvested and managed in a decentralised way to increase moisture availability to the crops through the growing season. The root zone itself can be used for storage to a great extent. To sum up grant funds will be utilised to take a mix of the following activities that will be detailed after joint planning exercise at each hamlet level.

  • a. Plantations (fruit trees / relevant Timber/ Lac hosts) in privately owned fallow / wastelands, supported by 30’ X 40’ model on degraded uplands,
  • b. 5 % Model in medium lands to support rainfed cultivation,
  • c. Land Husbandry in upland, medium upland and homestead. This will include gully plugging, terracing, levelling-bunding, contour bunding, land treatment e.g. liming, increasing organic matter , dealing with micro-nutrient deficiencies etc. to improved productivity of rainfed agriculture,
  • d. Seepage tanks in lowlands and valleys and small earthen dams on local drainage lines,
  • e. Micro-irrigation schemes to utilise surface water to provide life saving irrigation to Kharif crop and take up cash crops on a small scale in Rabi season. Also, some schemes, which tap into the sub-surface flow, created in the lowlands e.g. making a lowland well and lifting water for 5-7 families.