Groundwater augmentation as an adaptation strategy in Odisha

To augment irrigation sources in alluvial zone of Dhenkanal and Cuttack districts of Odisha, fifteen dug wells were designed and implemented as per the groundwater table. Pumping test was conducted to estimate the recharge rate for different dugwells which varied from 7.48 to 14.35 m3/hr. Accordingly, cropping pattern and command area (0.70-1.1 ha) for each dug well were established. After augmenting the ground water resources with improved irrigation system, 240% cropping intensity and net income of Rs. 39,000 to Rs.44450 per ha was achieved in different dug wells.

Drip irrigation system was installed in well irrigated command areas which increased the yield of different vegetable crops by 15-21 per cent over conventional method of irrigation. Maintaining optimum soil moisture and frequent nutrient supply matching with the crop water requirement under fertigation helped in yield increase over conventional system. 42 to 54 per cent water saving was realized by the farmers which enabled them to extend the area under cultivation with the same water. The study convinced farmers that adoption of water saving methods is key to achieve climate resilient agriculture.

Potential of location specific groundwater recharge structures in climate change adaptation:

Location specific groundwater recharge structures suitable for geohydrological conditions are assessed for its performance in terms of recharge rate and area of influence. Dry Stone Masonry Pond, Single Wall Masonry Structure, Cement Masonry Structure were constructed at Kherad, Som, Karget, Shisvi villages of Udaipur district, Rajhasthan. Daily monitoring of surface water level was carried out through gauging and table of the identified well situated in the downstream side of the structures was also measured on daily basis.

Similarly appropriate water harvesting cum groundwater recharge structures were constructed and evaluated at Dhari and Kodinar farms of Junagarh Agricultural University, Gujarat. The recharged water to aquifer from ponds storage (storage capacity-9604m3) was estimated as 13415 m3. The total harvested rainwater (runoff) during the monsson-2012 was computed as 13572 m3. The recharged groundwater from the pond storage can provide life saving irrigation of 5 cm depth to rainfed crops in 26.83 ha area during dry spell in kharif or irrigate 3.35 ha area of crop having 40 cm seasonal irrigation requirement in winter (rabi) season.

The total harvested water storage was computed as 4478 m3 through runoff in another 4 ponds at JAU farm Dhari and 4297 m3 was available for groundwater recharge. The recharged groundwater due to pond storage can be helpful for the life saving irrigation of 4cm depth to rainfed crops in 10.74 ha area in kharif or cover additional area of one hectare of winter crop having seasonal irrigation water requirements of 40 cm. Construction of another recharge structure of designed capacity of 31700 m3 is under progress at JAU farm, Mahuva which is located in coastal belt of Gujarat.

Artificial recharge through recharge well in percolation pond was taken up in PAP basin of Coimbatore, Tamilnadu by way of allowing the runoff water to pass through silt detention tank, water collection tank cum treatment chamber and erection of shaft with filtering chamber. The recharge during the monsoon and non monsoon period was computed based on water level fluctuation method

MODFLOW (USGS Modular Three- Dimensional Ground-Water Flow) Model was calibrated and validated in Vadachitur watershed located in the Parambikulam-Aliyar-Palar basin of Tamilnadu and simulated and observed water levels were compared for a period of 365 days. At a period of 365 days, storage in to the aquifer was 1.62 Mcum/day and flow out of the aquifer from storage was 4.82 Mcum/day. The water pumping out from the wells was 2.1 Mcum/day whereas recharge into the aquifer was 5.99 Mcum/day. The total inflow into the aquifer was 7.965 Mcum/day and total outflow into the aquifer was 7.954 Mcum/day. At the period of 365 days, the outflow was more than the inflow by an amount of 0.0011 Mcum/day.

These studies point to the potential of ground water recharge as a means to cope with climate variability both in high and medium rainfall regions. However the performance of these structures will be monitored annually in relation to rainfall to know to what extent this technology can help in drought coping.

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