Reassessing policy options requires a better understanding of climate impact on farm water management in India
Photo: iStock Embarking on an exploration of the intricate interplay between climate variability and its profound impact on crop yield, our recent paper, featured in the International Journal of Water Resources Development, unveiled crucial insights into the challenges faced by India’s agricultural sector.
In this blog post, we navigate the nuanced findings, highlighting the related water risks and offering valuable perspectives for informed policy decisions.
Seasonal climate change has been shown to affect expected crop yield and yield variability functions significantly. Changes in rainfall and evapotranspiration across seasons largely affect expected yields for most crops, such as bajra, chickpea and groundnut. However, high summer rainfall and low monsoon evapotranspiration extremes reduce groundnut and chickpea yield variability, respectively.
Rainfall in winter is inversely related to bajra, chickpea and groundnut yields. Though rice and sugarcane are positively related to winter rainfall, yields decline as rainfall rises above the optimal levels of 85.35 and 88.79 millimetres (mm), respectively. Yields of rice and sugarcane also reduce as evapotranspiration (combined processes that move water from the Earth's surface into the atmosphere) in the summer rises beyond optimal levels.
An increase in summer evapotranspiration decreases bajra, chickpea and groundnut yields at an increasing rate, with turning points at 54.04, 149.41 and 25.69 mm, respectively. Further, increased evapotranspiration in monsoon reduces yields of chickpea and groundnut, whereas rainfall in autumn is negatively related to bajra and chickpea yield.
Higher evapotranspiration in most of the seasons (except autumn) affects chickpea yield, whereas higher rainfall in most seasons (except summer) affects bajra yield. Monsoon maximum temperature is adversely related to yields of rice, groundnut and sugarcane, with turning points at 24.88, 37.34 and 27.62 degrees Celsius, where sugarcane is most susceptible to changes in maximum temperature across other seasons (except summer).
Similarly, a higher summer and monsoon minimum temperature decreases sugarcane yield at an increasing rate. The minimum temperature in winter is adversely related to rice, chickpea and groundnut yields, with turning points at 7.79, 9.95 and 13.14°C, respectively. With respect to rice, chickpea and groundnut, yield also declines as autumn windspeed rises above 1.08, 2.54 and 1.33 metres per second.
It is further observed that high rainfall extremes in the summer and monsoon reduce the risk of groundnut and sugarcane yields, respectively. A low evapotranspiration of 1mm below climate normal in autumn and monsoon decreases the yield variability of groundnut and chickpea by 36.71 per cent and 35.44 per cent, respectively.
Chickpea and groundnut yield risks, on the other hand, increase with low maximum temperature extremes in winter and monsoon, respectively. A low minimum temperature of 1°C below the climate normal in summer and monsoon increases the yield variability of groundnut and rice by 51.98 per cent and 35.71 per cent, respectively. It is also seen that high winter and low monsoon windspeed extremes enhance the risk of groundnut and rice yields, respectively.
The study considered differences in water availability due to climate variation as an important factor affecting crop production, requiring proper water management. Changes in winter rainfall and summer evapotranspiration negatively affect most crop yields. To mitigate the adverse effects of heavy rain in winter, diverting surplus water from croplands to storage facilities could be useful, as it could then be used to meet high crop water demands in summer.
High rainfall and temperature extremes are frequently the cause of flooding and drought, which increases crop yield variability. To reduce the adverse effects, effective drainage facilities are required to distribute the excess water throughout the seasons. Reallocating water to crops that gain from irrigation expansion (such as rice, chickpea and sugarcane) or substituting other high-tolerant crops could also increase farm production while reducing water loss.
Assessing the impact of climate change on crop production and production risk highlighted the varying sensitivity to weather variables and extremes across seasons, with significant variation across crops, largely in response to water elements. The variations in effects within and between seasons prompted crop-specific seasonal adaptation, emphasising the importance of sustaining long-term water availability.
Crop-wise assessment of climate effects enabled the identification of high-tolerant crops that could be replaced with low-tolerant ones. It also identifies crops that gain from irrigation, making irrigation diversification easier. Seasonal assessment, on the other hand, recognised changes in water availability due to climate change for crops during various farming seasons.
Excess water in a season could be saved to avoid yield loss and then used to meet crop water demands in water-stressed seasons. Major consumptive use of rainwater for elevated crop water demand would further relieve pressure on groundwater that would otherwise be harvested. Appropriate irrigation and water management would be extremely beneficial in achieving these goals. Using scientific techniques, modern irrigation would reduce the severity of climate shocks on crop production.
Greater emphasis and precision in understanding the scope and nature of climate change effects on farm water management in India are required to re-evaluate policy options. The planners must decide whether to continue running irrigation to defend farmers from climate threats or to make better economic use of scarce water resources by diversifying irrigation supply to higher-potential crops.
The government should improve the use of rainwater and predictive techniques to enable crop-wise water management and frame multi-prolonged climate adaptation strategies to address yield risks. Climate-smart agriculture should be given preference in policy and local governance. Successful programmes can be tied to many regionally viable and sustainable agricultural management programmes. Farmers’ progressive involvement in water management would result in beneficial outcomes in terms of efficiency, equity and economy.
Souryabrata Mohapatra is a researcher with core interests in climate economics and sustainability
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth
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