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Hydrological And Socio-economic Impacts Of Basin-wide Water Harvesting And Artificial Recharge Interventions In Coastal Saurashtra

Congress: 2015
Author(s): Vedantam Niranjan (Hyderabad, India)


Keyword(s): Sub-theme 10: Management of water resources,
AbstractINTRODUCTION

Systematic studies dealing with physical and socio-economic impacts of water management interventions at the basin scale are very few in India. The available research in the past highlights the downstream hydrological, socio-economic impacts (Bachelor et al., 2002; Kumar et al., 2006; Kumar et al., 2008), (Kumar and Amarasinghe, 2009; Ray and Bijarnia, 2006) and social & ecological (Kumar et al., 2008) impacts when intensive water harvesting is carried out in naturally water scarce regions. The empirical studies mentioned here were also from naturally water-scarce regions. In this context, the work done by Ambuja Cement Foundation (ACF) a philanthropic organization is an exception. Coastal Saurashtra in Gujarat, India is characterized by highly erratic rainfall, aridity, and seawater intrusion due to excessive withdrawal of groundwater from coastal aquifers for irrigation. Under such conditions, water resources must be judiciously managed to ensure crop production and domestic water-security. The objective of the study was to assess the hydrological and socio-economic impacts of three different types of water harvesting and groundwater recharge structures built in three different river basins, viz., Singoda, Somat and Sagavadi, in Saurashtra region in Gujarat.

METHODS / MATERIALS

The hydrological impact of groundwater recharge interventions are analyzed by comparing the pre & post monsoon fluctuation in water levels in wells which are likely to be influenced by the recharge structures with those which are not likely to be under the influence of recharge structures, which are under the same geological setting. At the next level, the impact was analyzed by comparing the yield of wells in terms of total number of hours for which well located in the influence area of recharge structures could be run before drying up and the discharge (m3/hour) before and after the recharge interventions and comparing it with that of wells outside the influence area. The Socio-economic impacts of the recharge interventions were analyzed both at farm level and village level. The environmental impact of the intervention was assessed by analyzing the changes in the composition of stream-flows in the river systems which are treated using artificial recharge interventions, vis-a-vis the percentage contribution of the "total estimated virgin flows" from monsoon and non-monsoon flows.

RESULTS AND DISCUSSION

While the average increase in water level rise in the wells (due to monsoon rains) surrounding the check dam post intervention was 31.60, it was only 25.06 feet for the wells located outside the influence area of the check dam. The average recharge induced by the check dams in Harmadiya village was estimated to be 3.6cm, which is about 4.5 per cent of the rainfall. An increase in water spread area created by these impounding systems was around 3024ha, during the monsoon of 2010. The overall increase in farm income per bigha of land, for the existing cropping pattern was estimated to be Rs. 3708, when only the area under seven important crops within that unit area was considered. Similar trend in cropping pattern shift was seen in the case of reservoirs created by the mined out areas and the link canals. A worrisome trend is the tendency among the farmers to shift to highly water intensive sugarcane, which earns them high returns per every unit of land, but gives very low water productivity in economic terms (Rs.3.6/m3) as compared to wheat (Rs.5.1/m3) and cotton (Rs.7.3/m3). The environmental impact of the water harvesting structures built in a series in Singoda basin is positive, as they create many lakes in streams of different orders. The water is also being used by women and children for bathing, washing clothes, animal drinking and recreational purpose. However, care should be exercised while building more structures in future in this basin, and should be limited by the excess flows from the medium reservoir upstream and the total residual catchments.

CONCLUSIONS

The check dams and other water harvesting /recharge structures built by ACF create impact on the farm economy of the area in several ways. First: the continuous recharge from the reservoir created by the structure keeps the water level in the influence area high. But, it is important to note that the effectiveness of the intervention lies in making water available in the reservoirs when water levels in the aquifer starts drawing down. As noted by Kumar et al. (2006) and (2008), in the content of hard rock areas of Saurashtra, during years of good rainfall, the aquifers overflow leaving no space for the incoming flows from the reservoirs. The contribution of check dam in providing additional recharge is evident from the higher, post-pre monsoon rise in water levels in the wells near the check dams as compared to those located away from the check dams. But, there are limits to water harvesting in these basins, imposed by the hydrology and stream-flows. The next generation of interventions in the area should focus on improving the productivity of use of water. As the study shows, with improved recharge from the water harvesting/recharge structures, the farmers are increasingly using the water from their wells to highly water intensive sugarcane, merely because it gives high return per unit of land cultivated. Water productivity of this crop in relation to the irrigation water applied is very low under the traditional method of irrigation. Hence the attempt should be to promote water efficient irrigation among sugarcane growers or introduce new crops which yield high returns, but consume less amount of water.
1. Bachelor, Charles, Ashok Singh, MS Rama Mohan Rao and Johan Butterworth., (2002) Mitigation the Potential Unintended Impacts of Water Harvesting, paper presented at the IWRA International Regional Symposium ‘Water for Human Survival’, 26-29 November, 2002, Hotel Taj Palace, New Delhi.
2. Kumar, M. Dinesh et al (2006) Rainwater Harvesting in India: Some Critical Issues for Basin Planning and Research, land use and water resources research, 6 (1): 1-17.
3. Kumar, M. Dinesh et al (2008) Chasing a Mirage: Water harvesting and Artificial Recharge in Naturally Water-Scarce Regions, Economic and Political Weekly, August, 2008.
4. Kumar, M. Dinesh and Upali Amarasinghe (Eds) (2009) Water Productivity Improvements in Indian Agriculture: Potentials, Constraints and Prospects, Strategic Analysis of the National River Linking Project (NRLP) Series 4, Colombo: International Water Management Institute.
5. Ray, Sunil and Mahesh Bijarnia (2006): ‘Upstream vs. Downstream: Groundwater Management and Rainwater Harvesting’, Economic & Political Weekly, July 1.

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