The draft Revised Master Plan for the city of Bengaluru has been put out for public comments and suggestions the last date of which is January 23, 2018. As with all master plans it lays out broadly what will be the infrastructure and land use plan for the city subject of course to many corrections at the neighbourhood level. Specially to look out for is the identification of lakes, tanks and the channels connecting them. Have they been identified correctly? Are the boundaries correct and clear? Are the feeder channels and the channels linking one tank to the other marked and protected? It would be good if citizens and citizen groups pay close attention to these features of the master plan and make sure to send in their comments.
One component of planning which is usually paid little attention to, is the soil and aquifer. Literally what lies below our feet. Aquifers are porous body of weathered rock which have the capability of storing and releasing water. The wells of old were dug into the aquifers to obtain the waters held in them. These aquifers can be considered as green infrastructure for a city as much as trees, forests and parks are. In Bengaluru alone, there could be up-to 10,000 wells and over 400,000 borewells providing 400 to 700 million litres of water per day to enable the city to meet its water demand.
Developing a good map of the aquifers, developing a management strategy to protect and fill them with clean water and reusing these waters sustainably would enable the city to become water secure. This should form part of the master plan for water of the city.
Lack of understanding
Several examples of the lack of understanding of aquifers and their correct management can be cited. A commercial complex reported problems of leaking basements after the heavy rains of last year, yet the water consumed by the commercial complex mostly for non-potable purpose such as toiler flushing came from the distant Cauvery. By digging three wells in the premises the groundwater could be tapped for the use of waters needed in the complex and the water table lowered, thus eliminating the basement flooding.
A swimming pool being built by the government in a suburb of the city pumps out groundwater almost daily to lower the highwater table. By digging a shallow well and linking it to the swimming pool, most if not all of the water requirement that the pool requires can be met by the shallow aquifer provided it is recharged adequately.
In another case, a commercial and housing complex dug a double basement for car parking. Since the aquifer was saturated, it pumped out clean potable water into the storm drain for months to empty it so that the basements could be dug. Aquifers act like groundwater banks storing water during the rains and releasing it throughout the year.
In areas with high depths of weathered rocks it would be unwise to dig double and triple basements and destroy the water holding capacity of the earth.
Globally the idea of ‘sponge cities’, urban areas that soak up rainwater , prevent flooding and provide water when needed as groundwater is gaining traction. A master plan for a city struggling to source water from distant sources must include the shallow and deep aquifers as green infrastructure. That would-be water and groundwater wisdom.
zenrainman@gmail.com
