In the absence of river basin thinking, Bangalore's planners have created a water architecture dependent on the Arkavathy and the Cauvery. A study by our water expert S. Vishwanath
A river basin is a hydrological unit from where any rainwater falling emerges from single point. Many rivers which are now running dry or are carrying loads of sewage are now being sought to be revived. A river basin approach is thought of as the best way to proceed ahead to restore the ecological system of our rivers.
In which river basin is Bangalore located? A common misconception is that we are fully in the Cauvery basin. A rude shock came to the water managers of the city when the Cauvery Water Disputes Tribunal indicated that only 30 per cent of Bangalore was in the Cauvery basin and hence was eligible only for a limited amount of water from the Cauvery.
Unfortunately, the planners, in the absence of river basin thinking, have created a complete water architecture dependent on the Arkavathy and the Cauvery. The Arkavathy is of course a tributary of the Cauvery and in the broader context, part of the Cauvery basin.
What came as a surprise is that a large chunk of Bangalore was actually in the Dakshina Pinakini or South Pennar or Ponnaiyar as the many names by which the river is known by.
Apparently the Tribunal's point was that this section of Bangalore has to make arrangements for its water from this basin for the section of the populace living here.
As Bangalore expands it is likely to move into the Palar and the North Pennar basins too. Sitting on a ridge leaves it the uncomfortable choice of being upstream in all the river basins it spans. The Nandi Hills, being the highest point in the region, is the origin of six rivers.
Single point dependence
Starting from 1894 till date the single point dependence on the Cauvery shows a singularly risky management approach. The city utility will now have to plan for water supply understanding its position in a river basin or basins. It will have to look at its role in the river basin planning. How much of resource will it draw or is allowed to draw from the river?
How much of catchment management will it do to ensure that the river flows freely and at least with adequate water for drawal for the city's need? How will it ensure the health of the basin by ensuring no pollution of the river either through sewage or even through solid waste dumping in the catchment? The river basin as a unit of hydrology and hydrogeology will increasingly become the unit of water resource planning. Water supply providers will all have to factor in what happens in the basin and the possible impact it can have on the future sustainable provision of the resource.
Make it better
Since we as a city live upstream the responsibility on the city is all the more towards the rivers. It cannot be that we only appropriate fresh water from all resources available, dump sewage, abandon reservoirs and run to farther fresher water bodies. This is unsustainable.
We need river basin institutions that will look at the rights to water in the entire basin and also look at the need for the river itself to flow, apart from ecosystem needs.
We need to move quickly on this one.