Groundwater depletion is experienced in several districts of Tamil Nadu state and Coimbatore district is heading in that direction. The average well failure rate is 47% for open wells and 9% for bore wells. The total cost of depletion for new wells varies from Rs 1,999 per ha to Rs 90,975 per ha. The electricity subsidy to the farmers has varied from Rs 22,621 per ha for coconut growers to Rs 25,498 per ha for banana growers as on 2004. The cost of irrigation per cubic metre (m 3 ) is less on large farms. The average net return with free electricity varies from Rs 0.14 per m 3 to Rs 1.38 per m 3 and is drastically reduced when electricity is priced at an economic cost, i.e. Rs 21.15 to Rs 20.14 per m 3 . The shift in cropping pattern towards high value crops helped the farmers to some extent to bear the cost of externalities arising out of depletion. The social cost caused by groundwater overdraft is about Rs 554.3 million, which may increase when the well density increases further. Suggested policy options are to change the cropping pattern to less water-consuming crops, to invest in watershed development activities, to change inefficient pumpsets and to adopt well spacing norms.

Purpose Changing climate has increasingly become a challenge for smallholder farmers. Identification of technical, institutional and policy interventions as coping and adaptation strategies and exploring risks of their adoption for smallholder farms are the important areas to consider. The aim of the present study was to carry out an in-depth analysis of adaptation strategies followed and the associated risk premium in technology adoption. Design/methodology/approach The study was carried out in the dryland systems of three Indian states – Andhra Pradesh, Karnataka and Rajasthan – and was based on a survey of 1,019 households in 2013. The flexible moment-based approach was used for estimating the stochastic production function, which allowed estimation of the relative risk premium that farmers are willing to pay while adopting the technologies to avoid crop production risks. Findings In all the three states, the risk premium (INR ha−1) was higher for farm mechanization compared to supplemental irrigation, except in the case of Andhra Pradesh. The higher the level of technology adoption, the higher the risk premium that households have to pay. This can be estimated by the higher investment needed to build infrastructure for farm mechanization and supplemental irrigation in the regions. The key determinants of technology adoption in the context of smallholder farmers were climatic shocks, investment in farm infrastructure, location of the farm, farm size, household health status, level of education, married years, expected profit and livestock ownership. Originality/value Quantification of the risk premium in technology adoption and conducting associated awareness programs for farmers and decision-makers are important to strengthen evidence-based adoption decisions in the dryland systems of India.

Groundwater is now a major source of agricultural water supply in many parts of the world. The value of groundwater as a new source of supply is well known. However, its additional buffering or stabilization value is less appreciated and even less analysed. Knowledge on groundwater's stabilization value is advanced by developing and estimating an empirical model using the case of tank irrigation systems in Tamil Nadu, India. Unlike previous work, the model uses cross-sectional rather than time-series data. The results show that for the case-study region, the stabilization function added approximately 15% to supply value. Scenarios with surface water and electricity price were incorporated in the model. Increased surface-water supply and electricity price caused reduction in groundwater use but the percent of stabilization value of groundwater increased. The findings are used both to suggest improvements in tank irrigation systems and to further contextualize knowledge of groundwater's stabilization value

A hybrid model incorporating the econometric and programming models was developed to quantify the impact of climate change on agriculture in Godavari basin, India. The Just and Pope production function was used to estimate the mean yield of crops and the variance associated with the mean yield and using the estimated yield, the multiple goal programming model was used to optimize the land and water use under mid and end century climate change scenarios. The results indicated that rice production will reduce during mid and end-century periods by 16% and 36% respectively and by incorporating the water and labour saving technologies in the crop production, the reduction in rice production will be eliminated during mid-century and it will be only 19% during end-century period. The overall water saving will be about 20% due to the adoption of these technologies. Technology up-scaling programs are suggested. Areas for future research are also indicated.

Irrigation tanks in India are common property resources. Tanks provide not only for irrigation, but also forestry, fishing, domestic water supply, livestock, and other uses. Using empirical results from a study of tank performance from 80 tanks in Tamil Nadu, South India in two time period: 1996-97 and 2009-10, this paper evaluates tank irrigation system performance in terms of economic output and revenue generation forirrigation and other uses.The results indicate that irrigation and other productive uses put together raised the total value of output at tank level by 12 % in 1996-97 and just 6 % in 2009-10. This may suggest that tank multiple use values are small and getting smaller, and therefore not worth consideration. However, it was also found that, while declining in absolute terms, non-irrigation uses provided the majority of tax revenues and still more than cover government's operation and maintenance expenditure (O&M) budget. This finding provides another reason to consider multiple use values and their linkage with overall system viability.