What has caused the water crisis in Bengaluru, neighbouring areas

Why the shortage

During last year’s monsoon, Karnataka received rainfall that was 18 per cent below normal, the least since 2015. Even the post-monsoon period did not bring much rain to the state. Like most other parts of the country, Karnataka receives a bulk of its annual rainfall during the monsoon, and it is this water that fills up the reservoirs and recharges the aquifers. A rainfall deficit in the monsoon months almost inevitably results in water stress.

Karnataka was not the only state to receive below-normal rainfall last monsoon. Kerala, for example, finished the season with a 34 per cent deficit. Bihar, Jharkhand and eastern Uttar Pradesh had almost 25 per cent deficit each.

However, what makes the difference in the case of Karnataka, as pointed out by Vimal Mishra, a professor of Civil Engineering and Earth Sciences at IIT Gandhinagar, is the nature of the underground aquifers in the area.

“South India has a very different kind of aquifer system. It is very rocky. The aquifers don’t hold a lot of water. They empty out quickly, and they also get recharged pretty quickly. What this means is that groundwater resources are not able to sustain for very long in the event of a prolonged dry spell. This is very different from the aquifers in north India, which have a much better capacity to hold water. This is why Bihar and Uttar Pradesh, which got even less rainfall last year than Karnataka, have not seen similar water scarcity,” Mishra, the Vikram Sarabhai Chair professor at IIT Gandhinagar, said.

“Aquifers in north India, once full, can hold enough water to sustain the demand for a couple of years,” he said.

Falling reservoir levels

Another direct consequence of low rainfall has been the relatively low level of water in reservoirs. Latest data from the Central Water Commission shows that Karnataka reservoirs are currently holding water at only 26 per cent of their full capacity, which is at least ten percentage points lower than what is expected at this time of the year. Instead of the nearly 8.8 billion cubic meters of water that is expected in Karnataka’s reservoirs at this time of the year, only 6.5 billion cubic meters is currently available. And this is depleting steadily. A month earlier, the state’s reservoirs were holding 7.78 billion cubic meters of water, CWC data shows.

Again, it is not just Karnataka’s reservoirs that have below-normal water levels. Other states in south India are facing the same problem, with Telangana being in a far worse situation. But the demands in Karnataka are different, and its reservoirs are depleting faster than those of the neighbouring states. Clearly, the state is being forced to draw more from the reserves even before the start of the summer season.

“Roughly about half of Bengaluru gets its drinking water through piped supply. The remaining half mostly uses groundwater for drinking purposes. The areas that have piped supply are not facing much disruption because this water is coming from the reservoirs. In these kinds of situations, when the rainfall has been scanty and reservoir levels are low, the tendency of the governments is to prioritise drinking water needs, especially in the urban areas. It is in parts of Bengaluru that are dependent on groundwater that the drinking water problem seems most acute,” Mishra said.

As summer rolls in, the state might be staring at an even bigger water crisis, as the demand goes up, not just from households but also from industry, agriculture and hydropower sectors. This is likely to continue till the monsoon rains arrive, hopefully in the first or second week of June.

Dealing with water shortage in Bengaluru, elsewhere

“There are a lot of long-term structural issues, like unregulated construction, systematic destruction of lakes, hindrances to the natural underground flow of water, and climate change, that affect the availability of water in Bengaluru. But these do not seem to be the immediate triggers for this particular ongoing event. This one has to do largely with the seasonal fluctuation in rainfall and the state’s inability to create capacities to deal with these kinds of variabilities,” Mishra said.

He said while the focus has been on Bengaluru — the main urban centre with a major international footprint — it was quite likely that the rural parts of the state were facing an even greater shortage. India still has not built capacities to deal with multiple-year droughts, he said.

“We have done some analysis on the last 800 years of data. We have found that the probability of two or three continuous years of drought at the national level is extremely low, but at the state level this is very probable; in fact, quite high. We will have to become resilient to such disruptions,” he said.

“The key obviously is to put value on water. It is not a free resource. Low or optimum consumption needs to be incentivised while wastage must be discouraged. How this is done is a matter of policy choice. But the use of ground water through the use of household pumps, for example, needs to be discouraged and minimised,” he said.