There is a deepening water crisis that political sloganeering has yet to recognise — perhaps due to an enduring belief that, regardless of the severity of the drought, the monsoons will return to normal. However, what remains unaddressed is the twin reality of droughts and downpours as ‘atmospheric rivers’.
The latter is a new meteorological phenomena, depositing massive volumes of water in relatively small areas in just a day or two. Havoc has been wreaked in places as diverse as Oman, parts of Kerala, Tamil Nadu, California, and Brazil. The lesson is that such excessive rainfall does little to compensate for devastating water deficits left by prolonged droughts: surplus water runs off too swiftly, and fails to replenish the parched aquifers, tanks, and ponds depleted during the drought cycle.
Water storage in aquifers is a valuable resource but gets depleted through over-extraction. Surface storage in reservoirs, tanks and ponds experiences accelerated evaporation rates with rising summer temperatures — a stark illustration is Egypt’s Lake Nasser located in the driest part of the world, where 10-20 billion cubic metres evaporate annually. But every crisis presents an opportunity. India needs to seize such an opportunity to redefine agricultural policies.
Farmers will need to be coaxed to increase their water productivity. Rural communities need to be sensitised to the fact that water balance is crucial for their prosperity and survival.
Varied impacts
Water balance is simple enough to explain — the inflow of water in a region should ideally match the outflow, with the latter preferably of comparable quality to the inflow. Different crops have varied impacts on this balance. For instance, broadleaf plants like bananas consume significantly more water, mainly through transpiration, in addition to the evaporation from irrigated soils and crop roots.
Cereals like rice and wheat, and crops like pulses and natural rubber, have vastly different ‘virtual water’ footprints. Cereals like rice and wheat directly and indirectly utilise 1,300-1,600 cubic metres of water to produce a tonne of grain. The equivalent ‘virtual water’ usage of pulses is over 4,000 cubic meters and of natural rubber over 700,000 cubic metres.
The good news is that there is an abundance of reliable data and excellent technologies available for tracking water balances on a real-time basis. The task at hand is to build grassroots support to appreciate the existential threats communities will be facing because of rainfall variability. Most of all, there needs to be an appreciation that sustained rural prosperity requires collective management of local ‘hard’ water budget constraints. Agricultural extension and researchers thereafter could help communities agree on suitable portfolio of crops that maximise farm earnings for every unit of ET or evapotranspiration rate.
Fortunately, water accounting is feasible today, thanks to the ubiquity of terrestrial sensors, satellites, and drones. These tools, linked with digital analytics and Artificial Intelligence, offer invaluable objective insights into appreciating the difference between sustainable and unsustainable water practices for the communities to act upon.
Simply put, water accounting tracks and reports on how water can be beneficially used for generating highest crop value while minimising water volumes lost through evaporation and transpiration. In addition, water accounting information enables communities to explore the feasibility of reusing non-consumed water fractions in the locality (in situations where agricultural run-offs and wastewater could be treated and reused at affordable costs).
The writer is Senior Fellow, World Resources Institute, Washington DC