A STUDY ON CONJUNCTIVE USE OF GREEN AND BLUE WATER IN DEEVANUR TANK IRRIGATED AREA

The world population grows at a pace of 1.3% per year. By 2025, global population is likely to increase to 7.9 billion. More than 80 percent of population will be living in developing countries. This growth in population combined with the expected increase in prosperity will put an enormous pressure on water resources. As a matter of fact, 36% of the 2025 world population is projected to be living in China and India alone, so water has become the biggest limiting factor to feed a growing population. It is estimated that 2000 litres of water is required to produce enough food for a person per day. This enormous pressure on water, forces us to apply better water management practices. So efforts have to be made to increase the water use efficiency. Conjunctive use of green and blue water can help in effective utilization of water resources. Therefore a study is carried out in Deevanur tank, which is located in the Deevanur village in Mailam block in Tindivanam Taluk of Vilupuram District in Tamilnadu, India to determine the water balance components in the command area using Crop Irrigation Water Requirement (CRIWAR 3.0) simulation model. So water management in India will rank high on the national and international political agenda of water allocation for irrigation. The study on conjunctive use of green and blue water is important for effective utilization of water resources and increasing the water use efficiency at this juncture. From this study the highest crop potential evapotranspiration (ETp) on March 2015, it is around 68,500m3. The lowest crop ETp found on June 2014, because of non-cultivation during this month. The lowest green water usage observed during non-rainy and non- crop growing months. Also it is observed that the highest blue water utilization seen on non –rainy months. The lowest blue water usage observed during high rainfall months. The highest potential evapotranspiration in fallow field seen during the non-cultivation months and lowest value observed in vice-versa. This study reveals that, about 31% or 1/3 of fresh water lost through evapotranspiration in fallow field in this tank command area. This study also found that the annual percentage of blue water sharing on crop potential evapotranspiration in Deevanur tank is 64% during the year 2014 -15.