‘Fuzzy logic’ to optimise water use

Should water be saved for power generation or should it be released for agriculture?

This is the dilemma the Karnataka government finds itself up against at the end of a season of failed monsoons. It’s much like the situation in the State a month ago, when crops had started to wither as reservoirs held back water.

However, researchers from the Indian Institute of Science (IISc.) have devised an algorithm that could possible ease the situation. The complex number crunching was tested out at the 71.50-TMC storage Lakkavalli gravity dam across the Bhadra in Shivamogga district that irrigates 1.68 lakh hectares across Chitradurga, Shivamoga, Chikkamagalur, Davangere, and Ballari taluk.

“In India, about 75 per cent of water is used in agriculture. But, the efficiency in use of water is very low, at just around 40 per cent,” says Pradeep Mujumdar, Professor at the Civil Engineering Department, one of the authors of the recently-published paper, who believes that calculating the amount and times for release of water can go a long way in conserving large amounts of water.

For the Lakkavalli dam, his team placed data gathering equipment in 15 locations in the command area of the reservoir that monitored four major crops of the region — paddy, citrus, sugarcane and maize.

Soil moisture content for each of the crops was calculated, and based on the rainfall received at these stations, the researchers could calculate — through a mathematical tool called ‘Fuzzy logic’ — the amount of water that needed to be released.

The study notes that the irregular release of water currently results in days where there is very deficit water for the crops, while the real-time model ensures adequate water for the crops at most times. For instance, in paddy, the current policy results in at least four days of severely-deficient water in the developmental stage that can push it to wilt.

In the reservoir side of things, the models show that on an average, even during a dry year, more than 16 million cubic meters can be saved, while 19 million cubic meters less can be released.

Data that may be helpful:

Important Points:-

• A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by utilizing the weight of the material alone to resist the horizontal pressure of water pushing against it. Gravity dams are designed so that each section of the dam is stable, independent of any other dam section
• The Bhadra Dam,which has created the Bhadra Reservoir, is located on the Bhadra River a tributary of Tungabhadra River in Chikkamagaluru district in Tarikere Taluk, in the western part of Karnataka in India
• Fuzzy logic is an approach to computing based on "degrees of truth" rather than the usual "true or false" (1 or 0) Boolean logic on which the modern computer is based.

Source :- The Hindu, 27-Nov-2015