Floods in Delhi
Issues
Flood Management
The Irrigation and Flood Control Department of Delhi is the sole incharge of execution, repair and maintenance of flood control works on River Yamuna and Najafgarh drain system. Till date both banks of the River Yamuna has been embanked through its run in Delhi right from Palla in the North to Jaitpur in the South. On the right bank. Delhi is protected by Rural Marginal Embankment (RME) from Palla to Supplementary drain, Jagatput Bund from Jagatpur to upstream of Wazirabad Barrange, Yamuna Bazaar Wall upstream of Old Railway Bridge and Rural Marginal Embankment MAdanpur Khadar from Okhla to Jaipur. On the left side, Delhi is protected by Left Forward (LF) Bund from Delhi - U.P. Border upto Wazirabad, Shahdra Marginal (SM) Bund from Wazirabad to Old Delhi railway Bridge and L.M Bund from Old Railway Bridge to NOIDA.
Analysis shows that while RME Palla meets the requirement fro with-standing a 25 year frequency flood, Jagatpur Bund, Yamuna Bazaar wall, Mughal Bund, L.F Bund, S.M Bund and L.M Bund all fail to meet this standard and would overtop in such a flood. In the eventuality of a 100 year frequency flood, all these embankments would fail to meet the requirement (Sharma 1996.)
Four major floods : profile
1977: Najafgarh drain experienced heavy floods due to discharge from the Sahibi River. The drain breached at six places between Dhansa and Karkraula, marooning a number of villages in Najafgarh block. Six human lives were lost due to house collapse. 14 persons died in a boat mishap. Crop damage was estimated at Rs 10 million.
1978: (September) River Yamuna experienced a devastating flood. Widespread breaches occurred in rural embankments, submerging 43 sq km of agricultural land under 2 meters of water, causing total loss of the kharif crop. In addition to this, colonies of north Delhi, namely, Model town, Mukherjee Nagar, Nirankari Colony etc. suffered heavy flood inundation, causing extensive damage to property. The total damage to crops, houses and public utilities was estimated at Rs 176.1 million.
1988: (September) River Yamuna experienced floods of very high magnitude, flooding many villages and localities like Mukherjee Nagar, Geeta Colony, Shastry Park, Yamuna Bazzar and Red Fort area, affecting approximately 8,000 families.
1995: (September) The Yamuna experienced high magnitude floods following heavy runs in the upper catchmen area and resultant release of water from Tajewala water works. Slow release of water from Okhla barrage due to lack of coordination between cross state agencies further accentuated the problem. Fortunately, the flood did not coincide with heavy rains in Delhi, and could be contained within the embankments. Nonetheless, it badly affected the villages and unplanned settlements situated within the river-bed, rendering approximately 15,000 families homeless. These persons had to be evacuated and temporarily housed on roadsides for about two months, before they went back to living in the river-bed. (Source : Sharma, 1996).
Settlement Patter in Flood Plain
A close analysis of the flood zoning pattern reveals that the high risk zones are the areas that have earlier been identified as unplanned or poorly planned areas having high population densities and sub standard housing structures. These include areas of North Delhi, and Trans Yamuna Area. Some of the colonies that have come up in these areas are at levels 3 to 4 meters below the 1978 flood level.
The community exposed to the highest risk from floods comprises the families living in the villages and unauthorized colonies within the river-bed. There are over 15,000 such families, having over 75,000 persons. Situated on the wrong side of the embankments, these people live on the edge of the floods, and are the first ones to find their homes washed away.
Direct effect of floods in the river Yamuna and the city's network of drains. These affect the population living in the Yamuna River-bed and on the banks of the river and drains.
Local flash floods and water logging increased surface run-off due to high ratio of hard surfaces leading to flash floods. This in turn badly affects the low lying areas, particularly the unplanned colonies which get water logged.
Risk of break in embankments
Protection from the river by embankments lead to a false sense of safety and development starts taking place in the shadow of these embankments. In the event of failure of these protective works, as has been seen in the form of breaches during past floods, the effect is devastating because the pressure of the entire embanked stretch is released at one point, and it takes the people by surprise.