SHIRPUR PATTERN – A REVOLUTIONARY CONCEPT OF WATERSHED MANAGEMENT
Water is basis for all activities of everyone’s life, not only human, plants and animal but human ecosystem as whole. Scarcity of water compels human to extract more and more from underground, which temporarily solves the problem but not for long. Hence it is need of time to conserve maximum surface water and its underground sources. Shri. Amrishbhai Patel from Shirpur (Dist. Dhule, Maharashtra) developed a new concept of watershed management which is potent medicine for drought and flood both. Before going into the actual concept we have to understand reasons that caused the problem.
Water tragedy in country
In Maharashtra Khandesh region, Marathwada region, some parts of western Maharashtra and eastern Vidharbha facing acute problem of water shortage regularly in summer season. Some parts of Marathwada region face the same even in winter. This is because of iritic and uneven monsoon.
In some parts of our country it is found that the region which had faced drought previous year face flood in consequent year. This is happening because of climate change. The traditional watershed channels are not able to control flood.
India’s annual rainfall is 1170 mm which is mostly received in rainy season and rest of the months are nearly with no rainfall. Though we get 1170 mm rainfall but it is unevenly distributed.
Deccan plateau of central and northern Maharashtra is rainfall shadow zone where people depend on rainfall and underground water for agriculture and day to day usage. In these areas rainfall is nearly 700 mm which is much below national average. Here people harvest underground water for irrigation which is reducing underground storages deeper and deeper.
Rainfall and current policy:
India as total is not deficient in rainfall but lucky among few satisfactory rainfall receiving nations. If we decide to conserve maximum out of rainfall that we receive in monsoon and retreating monsoon using Shirpur Pattern then we’ll be not only able to irrigate our fields in arid region but also keep extra water for mitigation of subsequent drought year. Following changes occurred in rainfall pattern,
- Total rainfall is not decreased rather in some parts it is decreased.
- The unevenness of rainfall has increased.
- Total period of receiving rainfall is decreased. It means now within short time rainfall gives maximum water.
- Because of reduction in period of rainfall soil and water get minimum time for infiltration and most of the water lost as water erosion along with soil erosion. Minimum is the water & soil contact period minimum is infiltration.
- In good olden days rainfall mostly had been received with low intensity but longer time compared to present days. This had given more time for water to remain in contact with soil and useful for underground storage. Very less amount of water (3% in Deccan area) get percolated in underground storage
- Water readily joins main channels and goes to river channels and then into the sea.
Deccan Plateau system and drainage:
Deccan plateau of India consists of Maharashtra, Telangana, North Karnataka, some parts of Madhya Pradesh and Chhattisgarh. During formation of Deccan plateau, molten magma got spread over land and gave black colour to newly formed soil. This process of spreading of molten magma took place many times on the same area hence when we take section of soil profile we find many stratas of black soil material followed by yellow soil/silt, sand, Gravel and lastly rocky layer. From black soil layer up to gravel layer is called Soft Layer and Rocky layer is called Hard Layer. Such soft and hard layers get repeated several times in Deccan plateau. In these layers black soil layer act as barrier for water percolation and hence it minimizes rate of recharge of underground water sources. While sand layer and silt is most important layer which has huge capacity to hold water in it. Sand holds about 30% of water to its volume means 1cu.m sand holds about 300 liters of water. This water contributes to underground water and water to wells and bore wells in farms. Also like sand silt has capacity to hold 2.5 % of water in it means 1cu.m silt holds about 25 liters of water. If we have such natural storage available, we can develop small watershed projects like Shirpur Pattern to mitigate water scarcity at domestic level itself. It will make a village self-dependent for irrigation and there will be no need to depend on medium and Macro irrigation projects.
What is Shirpur Pattern?
Traditional watershed have natural streams with natural width and depth. Also these channels has driven alluvium at base which is very fine and does not allow speedy infiltration. Because of having less width traditional watershed channels hold less quantity of water. Also because of having less natural depth it percolate less water to underground resources, as percolation barriers from channels have not been removed while constructing check dam. Also in such traditional watersheds, water gets stagnated for a long time and evaporated most of its part as vapour. More is stagnation time due to percolation barriers like alluvium, black soil layers, yellow soil layers etc. less is percolation and more evaporation. That’s why though we observe more water in traditional watershed we feel it’s working but most of the time it’s not reality. Such watersheds are not watersheds but evaporation tanks only which are unable to current water problem.
In Shirpur Pattern, watershed channels are considered most important thing for conservation. In this watershed pattern width and depth of channels made 3 to 4 times more than natural measurement. That increases volume of channels to accumulate more water. Also due to increase in depth, at least one soft layer opens which helps in lateral and downward entry of water easily through sand and silt layers. Also percolation barriers get reduced as water doesn’t come across such barriers like Black material. It also increases hydrological pressure at bottom surface in tank area.
That results in increase in rate of downward movement of water. As speed of percolating water is more hence a negligible part of water gets evaporated in such watershed area that in real sense increases underground water resources. Also at appropriate distance by considering at least 1 or 2 soft layers check dams are constructed for percolation and lateral movement of stored water. Channels provided with chain of check dams which hold water in watershed/captive area itself and reaches underground sources of local area and make available water to localities’ in summer as recharge in their wells. In deficient rainfall such watersheds accumulate maximum water and increase recharge efficiency. Also in flood condition it accumulates more water in upstream captive area itself as its volume is more than natural watershed that reduces water flow in main river course and minimizes flood conditions at downstream and river bank area. Hence Shirpur Pattern is beneficial for both flood and drought.
Advantage of Shirpur pattern.
- It accumulates more water than traditional watershed structures.
- It increases infiltration and percolation and effectively recharges underground water resources.
- It reduces risk of both floods and droughts.
- It is a kind of watershed decentralization.
- It increases water availability 2-3 times more to watershed area.
- It overcomes from evaporation, stagnation and overflow like problems.
- It minimizes soil erosion.
Ground Result of Shirpur Pattern
This project is undergoing in many villages of Shirpur Tahsil in Dhule District of Maharashtra. Several villages adopted this pattern successfully. In many villages where only 25-30% of land was under irrigation which became 80-85 % after adoption of this pattern. The farmers were also advised to use micro irrigation systems to minimize water wastage and thereby use conserved water efficiently.
In 2012, many district faced drought in Maharashtra even worse than 1972 drought. In Jalna district the situation was worst. This is the district which has been facing drought conditions since many years continuously. The city people took it as challenge and by raising proper fund they not only solved drinking water problem and domestic use of it but also for irrigation to farms. Chief Minister and deputy chief minister gave green signal for his proposal. Under his guidance government built many check dams according to Shirpur pattern. In subsequent year with average rainfall all dams overflow with water and much of underground got recharged as farmers found their wells with high water level in summer.