By Dr. R. H. Patil, Department of Agricultural Meteorology, UAS, Dharwad
Hubballi – Dharwad Municipal Corporation forms the 2nd largest populated area in the state of Karnataka after Bengaluru. Between 1991 and 2001, the population of the twin cities grew by 21.27% from 648,298 to 786,195, which further increased by another 20.04% to reach 943,788 by 2011. Now, assuming an average of 19-20% decadal growth between 2011 and 2021, the total population of the twin cities may well have crossed 11.30 lakh.
With an ever-increasing population, domestic water demand is increasing exponentially, and supplying water has been one of the HDMC administration’s priority issues throughout the year, especially with the implementation of an ambitious project to supply water 24/7 to all parts of the twin cities. Currently, the main source of drinking water is the Malaprabha and Neersagar reservoirs, which are supported by scores of bore wells dug by both corporations and private citizens.
As per the Central Groundwater Board report, in India, some 80% of the drinking water requirements in rural areas, 50% of the urban water requirements and > 50% of the irrigation requirements are met with groundwater, and it is not much different in Dharwad district and the twin cities. The groundwater in Dharwad and Hubballi taluk is already overexploited and the quality of the water is deteriorating due to nitrate/fluoride contamination and industrial pollutants. Besides, the groundwater level is dropping alarmingly fast in many places.
In this regard, HDMC has embarked on a novel project to construct groundwater recharge structures around some 200 public bore wells spread across the twin cities. This is a very small, but welcome step in the right direction to make the best use of excess rainwater from the monsoon period to recharge bore wells to enhance not only the quality of water output but to increase the longevity of bore wells to achieve sustainable water management and supply to the twin cities.
However, the scarcity of quality drinking water is severe and widespread; hence, most areas in the twin cities get municipal water once every 5 or 6 days. Irregular water supply, particularly during the summer months (March-May), encourages citizens to dig more bore wells in order to secure their own source of water for daily consumption.
These bore wells present in residential compounds also need a groundwater recharge structure built around them. This can be easily achieved through a roof rainwater harvesting system connected to a recharge structure within each residential compound. HDMC must encourage already built houses with bore wells to capture and store roof-top rainwater within the compound for reuse and recharge of bore wells and make it compulsory for new buildings to have a “bore well recharge structure” in place before issuing a completion certificate.
Like every residential compound is built with a municipal water storage underground tank, HDMC must make it obligatory on the part of citizens to build a separate underground tank to store roof-top rainwater or divert the same to a bore well recharge structure.
Not only will this improve bore well water output and quality, but it will also help to reduce flooding in cities during peak monsoon months, as well as the financial burden on HDMC from flood damage to city amenities, drainage systems, roads, and buildings. Roof-top rainwater harvesting, storage, and use to recharge bore wells must be recognized by the public, and such structures must be included in the planning and construction of residential houses and apartments.
HDMC must also create public awareness programs in this regard and bring in regulations for effective implementation to achieve a sustainable groundwater water management and supply system for the twin cities for a bright future.