Water is the key to life. Cities and towns were formed because of access to it, and the human body cannot live without it. The theme of 2019 World Water Day was "leaving no one behind." Access to clean water is a basic human right. According to the Water.org, 844 million people, roughly 1 out of 9 people on the planet, do not have access to safe water. The organization also points out that about 6 times the U.S. populations does not have a water connection to their house. Many water stressed countries are in developing nations of the world, but increasingly, water availability is an issue for places like Cape Town, Tokyo, Sao Paolo, Beijing, Melbourne, and London. Even in the United States, major cities in the West and Southeast are water-challenged. Speaking of challenges, the sixth largest city in India, Chennai, has been in the headlines recently (but not enough in my view) because it is literally out of water. Trains are being proposed to bring water to a city with over 7 million people. Satellite images released this week by NASA provide a stark look at the situation.
Data on the Water.org confirms that 159 million people depend on surface water from reservoirs, rivers, lakes, and streams for basic water needs. As of late June, the Central Water Commission (CWC) reported that 65% (roughly 2 out of 3) of India's reservoirs were dry. Of 91 reservoirs, 11 are completely dry, and overall storage position is inadequate. News18.com provides a comprehensive breakdown of the CWC report at this link, but here are some statements from their website story:
Region-wise data analysis shows majorly the reservoirs in eastern, western and southern regions of the country are facing high shortage of water. In the central zone, Uttar Pradesh and Chhattisgarh are affected, while the situation in the northern part of the country is better. In the five regions across the country, namely northern, eastern, western, central and southern there are 4, 14, 27, 10 and 30 reservoirs, respectively, where 40 per cent or below storage of water is available.
NASA's Earth Observatory released the "before" (May 31, 2018) and "after" (June 19, 2019) satellite images of Puzhal Lake. It is a rain-fed lake in the southern state of Tamil Nadu and is one of four reservoirs that serves the city of Chennai. The satellite images are from the Operational Land Imager on Landsat 8. As of June 21st, the four reservoirs were at 0.2 percent capacity according to the NASA Earth Observatory website.
Why has drought been particularly bad in India this year? To answer this question, an explanation of the Indian monsoon is needed. People often misuse the term "monsoon" as storm with a large amount of rainfall. The actual meteorological definition of monsoon is focused on a wind system and its periodic reversal. The Encyclopedia Britannica definition of the Indian Monsoon is written by one of former meteorology professors at Florida State University, legendary scientist T.N. Krishnamurti. The entry read on the encyclopedia website reads:
Indian monsoon, the most prominent of the world’s monsoon systems, which primarily affects India and its surrounding water bodies. It blows from the northeast during cooler months and reverses direction to blow from the southwest during the warmest months of the year. This process brings large amounts of rainfall to the region during June and July.
The wind system responds to changes in the surface heating of the Indian subcontinent during the warm and cool seasons. The southwest summer monsoon rains have been delayed this year. Chennai has received very little rain over the past several months, and the northeast monsoon season was very weak in 2018. The NASA Earth Observatory summary also cites the National Institution for Transforming India (a government think tank), which has Chennai on a list of cities that could run out of groundwater within one to two years. Forecasters predicted a sluggish start to the monsoon back in April. Outlooks suggest that things will pick up later in the Summer. This is critical since the Indian monsoon provides about 70% of annual rainfall needed by India for agricultural and life-sustaining needs. The lack of rainfall has likely amplified brutal heat conditions in India this year also.
The situation in India is particularly interesting to me as a scientist because one of my research projects at the University of Georgia has used satellite-derived rainfall and population data to quantify available precipitation per person around the globe. A prototype "Precipitation Per Person (PPP)" map for 2014 to 2017 is presented below. China and India both have relatively low PPP. This may be surprising since both countries receive a significant rainfall throughout the year. However, larger populations mean less available precipitation per person. This may indicate that precipitation alone could not theoretically sustain a population assuming no groundwater, managed water supply, or other augmentations. As noted earlier, the reservoirs sustaining Chennai are rain-fed. My doctoral student Ansley Long is applying a similar analysis in the water-stressed desert Southwest United States to assess needs of indigenous people on reservations.
