Chennai, India out of Water

Chennai, India has run out of water. The metropolitan area Chennai, once known as Madras, is home to 9 million people without adequate water. Chennai’s reservoirs and lakes are parched- with less than 0.2% of their reservoir's capacity full; and the city’s groundwater wells have run dry, too. To keep people alive local authorities are trucking in water and desalinating seawater, but the overall supply is 60% of what the government calls “ the city's basic requirement”- private companies are also trucking in water, but there is just not enough.

The images below are of Puzhal Lake, one of the four main reservoirs that serves the city taken a year apart. The first image was taken the last week in June 2019 showing a dry lake bed; and the second image taken in June 2018 shows a blue lake. The images are from NASA’s Earth Observatory.

from NASA

The water shortage is partly caused by low rainfall over the past few months; and partially by poor water management practices. In 2018, the city experienced one of its weakest northeast monsoon seasons, which runs from October to December and provides a large portion of the area’s annual rainfall. In addition, the southwest summer monsoon season  that should have started last month and run through September has been delayed across most of India. So far only short rainfalls have fallen in Chennai.

India is the world's largest user of groundwater and the north-east monsoon, which brings most of the water to this region in October and November, is unpredictable. Some years it pours, and in other years, it just fails to show up or does not carry enough water. Bangalore, Hyderabad and Delhi are all facing water shortages. It was reported that 65% of the country’s reservoirs were running dry. Growth in cities and development has been pursued without regard to water availability and sustainability.

The BBC reports that between 1980 and 2010, the land area of Chennai covered with buildings increased from 47 square kilometers to 402 square kilometers. Meanwhile, wetland areas declined from 186 square kilometers to 71.5 square kilometers. This has reduced the recharge of groundwater in the region as water demand has increased pumping. Groundwater recharges at various rates from precipitation. To recharge groundwater, it must rain (or snow) and the soil must absorb the water. Changes in rainfall patterns and impervious ground cover can impact the recharge rate of groundwater.

The Gravity Recovery and Climate Experiment (GRACE) satellite mission from NASA has been monitoring groundwater for almost 20 years. Two papers analyzing data from the first 10 years found that the Arabian Aquifer System, an essential water source for more than 60 million people in the Middle East, is the most over-stressed aquifer on earth. The Indus Basin aquifer of northwestern India and Pakistan was the second-most over-stressed and supports a much bigger population that is rapidly changing development. Water management practices and water planning desperately need to change. For too long India only land availability has limited development, not water availability and sustainability.