IIT Bombay Develops A Smart Irrigation Plan To Save 10-30% of Irrigation Water In Drought-Prone Regions
Researchers from the Department of Civil Engineering and Centre for Climate Studies at the Indian Institute of Technology Bombay (IIT Bombay) and the Indian Institute of Tropical Meteorology, Pune (IITM Pune), have developed a method that addresses the issue of water in drought-prone regions. In their recent study, they combined extended-range weather forecasts (1 to 3 weeks ahead), generated by IITM, Pune, satellite soil moisture data processed by IIT Bombay, and a computer model, to predict the amount of irrigation water needed up to three weeks, on a district and sub-district scale.
Earlier, during their pilot study in Nashik, Maharashtra, the researchers found that some well-to-do grape farmers used local soil moisture sensors. If the soil moisture sensor detects soil dryness, the farmers irrigate the grape farms. If the irrigated grape farms receive rainfall, the irrigation water gets wasted. To avoid water wastage in already shrinking groundwater locations, the authors suggested including weather forecasts.
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“During our pilot study in Nashik, we included local weather forecasts in the soil moisture data and showed farmers that groundwater can be conserved up to 30 %. We initially predicted up to one week (short-range) ahead,” shares Prof Subimal Ghosh, from IIT Bombay.
During this short-range prediction, researchers fed weather forecast and soil moisture data into a computer model that checks the possible amount of rain, the water capacity of the soil, and the water requirements of each crop. The computer model provides details on when and how much water would be needed for the crops. If the model predicts no rainfall in the coming days, it will suggest irrigating crops now. On the other hand, if the model predicts rainfall that can increase the soil moisture, it might suggest avoiding irrigating crops. Their findings showed that the grape farms could consume 10 to 30 % less water without compromising the yield. This approach prevents overwatering the crops and saves water.
The team extended their methodology in 12 sub-districts of Bankura, a drought-prone district in West Bengal. They considered five major crop varieties, i.e. maize, wheat, sunflower, groundnut, and sugarcane, a combination of cereals, oil seeds, and cash crops. These widely grown crops have varied growth patterns and water requirements. Each crop variety has a varied root zone depth, the extent below the soil surface to which a crop’s roots reach for water and nutrients. It is essential to retain soil wetness up to this level. When plants do not get enough water, they sense the water stress. To conserve water, they close stomata, the tiny pores on the leaf surface, meant for the exchange of gases.
The researchers used global soil maps and integrated satellite and field data to include soil moisture data such as root zone depth, soil texture, porosity, water-holding capacity, water conductivity, and stomatal closure. The researchers collected water consumption, monthly rainfall, root depth, and irrigation water requirement data from the Food and Agriculture Organisation (FAO) resource, IMD database, and IITM Pune.
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“Our computer model depicts the natural process by which plants draw water from the soil, their adaptation during a water stress, and their response during a water balance after irrigation or rainfall,” says Prof Ghosh.
The study methodology acted as a real-time advisor for water management. The researchers used the computer model and validated it with actual soil, weather, and crop requirements data for all the crops for the upcoming three weeks. By implementing this plan, the crops can consume less than 10 to 30% of the water usage compared to the traditional irrigation methods across all 12 sub-districts.
“We did not want to make the model very crop-specific, so we have developed more generalised equations. We used a very simple ecohydrological model that employed weather forecasts and soil moisture data, which can be adjusted based on the region and crops,” adds Prof Ghosh.
The extended-range weather forecasts can help in forecasting district-level water requirements and can assist water management. With the possibility of replicating across wide crop varieties and soil types, the approach aids in efficient water usage. “To expand this effort to other districts, we must convince the farmers that the model is beneficial. We are planning to discuss with farmers in villages to install a few sensors and develop an advisory system,” shares Prof Ghosh.
The study highlights how weather forecasting, remote sensing, and computer simulation can be joined together to assist farmers and water managers in effective irrigation management and reduce groundwater dependency.
This work received financial support from Department of Environment, Government of West Bengal; DST-Swarnajayanti Fellowship Scheme; Strategic Programs, Large Initiatives and Coordinated Action Enabler (SPLICE) and a part of the Climate Change Program (CCP); and Oracle Corporate Social Responsibility Fund.
