The city of Thiruvananthapuram is blessed with several hillocks and valleys and is often referred to as a city with natural drains. Though the city has a unique topography of numerous elevations and inclines, it has never been effectively planned and utilised in general, and particularly in terms of draining of rainwater.
Continuous heavy showers that sustain for a couple of hours often result in drainage clogging and heavy flooding of all our city roads. Pre-monsoon de-silting activities have become mere customary and never been imbibed any thoughtful proactive ideas. The city area experiences waterlogging to a large degree mostly owing to haphazard pattern of development, featured by small and fragmented house plots, narrow ducts, and blatant encroachments compared to its peripheral counterparts with larger open spaces that could manage larger volumes of water.
Data available with the Meteorological Department do not underline any substantial increase in rain over the years to account for the flood havoc. Yet, our roads get flooded within a few hours of rain. On closer observation, the unprecedented flooding of city spaces largely points to a single factor, namely, cementing or paving of tiles over all open spaces available. The figures available with the State’s Commercial Taxes Department affirm the increased sales turnover of exterior tiles over the past several years.
Till recently, rainwater was never ‘managed’ and a large portion of it was left to permeate the soil. Tiled grounds would not allow rainwater to stay even for a moment but prod instant flowing down, resulting in lightning floods in the low-lying areas of the city that could lead to greater calamities.
The district is predominantly covered with laterite soil,which has higher water-holding capacity than sandy soils seen in coastal areas, and allows water to percolate deep and helps recharging the groundwater levels, say experts in the State’s Groundwater Department. It would even charge the water which is blocked deep inside rock formations, though the channels that feed the deep reservoirs are usually unknown. The city’s soil structure gradually starts changing from laterite to loose sand at a distance of about three to six km off the coast, they say.
The Kerala Municipalities Building Rules, 1999, clearly emphasises the need of rainwater percolation and mandates sufficient opening in the plot where houses or buildings are constructed and exempts only those with impermeable soil. Through an amendment in 2001, it mandates 50 per cent of the required open space to be left unpaved, but this is often breached, as no follow-up inspections are carried out once a building obtains its TC number.
The Groundwater Department, which keeps a constant vigil of groundwater levels, opposes even box culverts used for drainage and cementing of drains’ floors. Experts with the department suggest providing water-collection pits at regular intervals all along the draining path, a very effective and zero-cost measure which would immensely help groundwater recharging. The draft document of the city’s Master Plan that came out in 2012 has attempted a comprehensive approach for an overall development of the city but was kept at bay. Hence we are still forced to follow the city’s archaic Master Plan formulated in 1971 which was based on the demography of 1961. Provisions were included in the new draft document to retain whatever available public open spaces in the city’s periphery as water retention areas. In the past, the city was blessed with large paddy fields, free-flowing canals, and numerous ponds, all of them functioning as natural reservoirs to accommodate rainwater. But unplanned urban growth led to this cul-de-sac and foiled all scope for suitable rainwater retention areas within the city.
