Rainwater is an immensely important resource for us. Rainwater seepage forms a self replenishing and useful source of pure and fresh water, and is being continuously depleted due to industrialisation.

Since (seasonal) rain water is retained in water holes and ground water reserves, their regular recharging has to be ensured by maintaining forests that helps percolation and slopes that provide larger surface area for natural percolation of rain water. Urbanisation, deforestation, leveling of slopes, sand mining, quarrying, unscientific construction of roads etc. have significant deleterious effects on maintenance of water bodies and recharging of ground water sources. Contour bunds, river bed maintenance, aforestation especially with plants that reduce soil erosion are important for recharging. While trenches and contour bunds could improve water availability in plain areas like Tamil Nadu, sloped land in areas like Kerala would need optimal land use and water conservation. Unscientific infrastructure building, misuse of forest land, irrational violation of coastal zones etc. can mar natural collection/ seepage of water underground.

Roads, paved courtyards and floor coverage hasten the flow of storm water to sea disallowing water to seep under soil to recharge our river life lines. Due to the peculiar geographic setting some states like Kerala and Mizoram, the surface run off determines the ground water level. Flow rate of a drop of water is 3m per second. If the water is allowed to seep through soil, the underground run off would be very slow; ie. takes three days to seep through 3m. Such slow seepage would maintain the recharging o the rivers and water holes. About 92% of rainwater Kerala receive, flows to the sea within 44hrs. Paddy fields (Wet land) besides being seats of food grain production are potent reservoirs of water that replenish the of ground water level.

Kerala has a road density of 417 Km/100 Sq.Km (national average is 100.39 Km/100 Sq.Km). Length of road per lakh population is 509.23 (national average is 321.3 Km.).This looks strange when one reflects it on the fact that the per capita landholding of Kerala is < 0.13 hectares and croppable land <0.1 hectares. Frequent, (almost daily) accidents in Kerala and the rising death rate must make every one sit up and think. Research shows that traffic volume especially on National Highways is likely to exceed three times road capacity in 10-years and six times in 20 years from now. (10-12% traffic growth rate). In the light of the frequent landslides in hilly regions and the disastrous havoc of Uttarakhand.

Scientific planning of roads: Ideally Roads shall be planned only on what geologists call “divides”. Divides are natural peaks atop slopes with the terrain slanting on either side. Roads constructed on divides are supposed to have minimum landslides as they would not transgress ‘flow channels’ of rain water. In areas like Foot hills of Himalaya, Kerala, Assam, Andamans etc. one comes across frequent landslides. A close assessment would show areas where roads are made by cutting slope it would drastically reduce the surface area which is expected to help hold and percolate water underground.

By Prof. V. Ramakumar


Also See:
Human or Environment: What should be given preference?

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