Bangalore isn’t just poised to lose its ‘garden city’ tag, but is alarmingly on its way to desertification, according to experts. A series of studies conducted over a five-year period has substantiated this claim.
Speaking to DNA, former head and principal scientist at Indian Council for Agricultural Research, Dr NG Raghu Mohan, who is also a soil and water resource consultant, says Bangalore’s depleting underground water table and shifting seasons are signs of gradual desertification. Earlier, citizens experienced prickly summer heat during March, but now, February seems like summer. The seasons have advanced and the moisture content in the air is almost lost.
Dr Mohan has studied the climate and soil of Bangalore over the last decade and says that there is a yardstick to measure desertification. One is when evaporation is more than precipitation. Earlier in Bangalore, evaporation was equal to precipitation, like in Pune, and Bangalore then experienced heavy rainfall. But now, the number of rainy days and quantity of rainfall has reduced. Now, Bangalore receives 540mm and some times 300mm of rainfall, compared to 1000mm it received earlier.
Noticeably, vegetation has become scarce in the city and its outskirts.
Lakes are vanishing and soil moisture is depleting. Therefore, the number of days the soil can release moisture to the plants has also reduced because of the presence of clay pan. This is presently 50cm below earth’s surface. This restricts soil digging and absorption of moisture.
“Desertification is not visible, but it’s occurring gradually. Peripheral areas of Bangalore such as Magadi, Hoskotte and Anekal are also experiencing increased evaporation. Bangalore’s soil is becoming desert-like as rainfall is reducing and summer heat is increasing,” he says. Climate in an area is humid when there is a rainfall of at least 180 days per year, and evaporation is less than precipitation. It’s semi-arid when the number of rainy days is 90; it is arid when there are 60 rainy days and a desert when the number of rainy days is less than 30.
Environmentalist AN Yellappa Reddy warns: “If we start exploiting and digging more borewells, underground water will be depleted and Bangalore will become a desert in a few years. The impact of desertification is difficult to assess as little is known. Neither the government nor citizens are concerned about it. The heat island effect is also adding to this.”
Studies have proved that glass and concrete structures are adding to the desertification, as the temperature in their vicinity is always high.