«URBAN FLOODING AND ITS MANAGEMENT 1.0 INRODUCTION Flooding in general and urban flooding in particular is not a un- known event in world and in ...»
Deficiencies in the drainage system (Planning, Execution & Maintenance):- The master 6.6.9 plan for drainage of Delhi was prepared in 1976 and sent to Delhi Administration in 1981 considering problems and habitation at that point of time and did not consider for future urbanisation and particularly rural–urbanisation and unauthorised colonies. Every department/ civic bodies in Delhi plan construct and maintain their drainage in isolation without consideration of overall integrated drainage and sustainability resulting in flooding.
6.6.10 Failure of pumping installations due to inadequate capacity or the failure of electric supply.
6.6.11 Multiple authorities in the city but owning responsibility by none. Less co-ordination among various Govt and civic bodies like MCD, PWD, DJB, I&FC, BSES, NDPL, NDMC,Cantt, CPWD etc. Control of Operation of barrages at ITO, Chilla and Okhla on river Yamuna are not with Delhi but with UP and Haryana which regulate only at request of I&FC dept of Delhi.
6.7 PREVENTIVE MEASURES UNDER TAKEN/PLANNEDAfter every flood in Delhi and experience gained, then Delhi Administration and present Delhi Govt has taken various preventive measures to curb floods in Delhi which resulted in safe living in Delhi to a great extent. These are illustrative and lot more are yet be done.
6.7.1 Construction of flood protection structures
• Marginal Bunds on left bank of River Yamuna, Marginal bund on right bank u/s of Wazirabad was constructed. These act as barriers for flooding.
• Regulators were constructed on Najafgarh drain.
• After floods of 1978, the banks of river Yamuna has been raised, a large number of spurs, bed bars, studs and Left Forward bund have been constructed to protect the embankments in Delhi territory. Raising of right embankment from Wazirabad barrage d/s is under consideration for a discharge of 3 lac cusec.
• Regulators with mobile pumping arrangement had been made where there is frequent risk of main Drain/River flowing at higher level than max out fall level of outfalling drains like at Chilla, Jahangirpuri drain, Supplementary drain and at all the 15 outfalling drains into River Yamuna.
• Channelising, lining etc has been undertaken in Supplementary drain to cater for a design discharge of 5000 cusec in first phase from Kakrola regulator, for 10000 cusec from Rithala d/s in Second phase and with 15000 cusec d/s of GTK Road in third phase. The proposal for phase II and III are under consideration.
• With the construction of Ajmeripura Dam on Sahibi River in Rajasthan, Masani Barrage in Haryana, and remodeling of Najafgarh drain including construction of Supplementary drain has reduced the flooding in Delhi.
6.7.2 Improvement of drainage efficiency
• Desilting, cleaning of road, bell mouth, gullies, removal of debris, solid waste materials from all drains of all depts. /civic bodies is being coordinated by the E-in-Chief of MCD.The committee also to make sure that all drains are checked and cleaned before monsoon to ensure that they are not blocked or collapsed. Desilting reports and certificates are being obtained from all owning agencies before 15th June every year.
• Constructions of cunnette in NG drain for 100-150 cusec capacity flow.
• Najafgarh drain, Supplementary drain, Jahangirpuri drain, TDI, II, Shahdra out fall drains etc carry lot of silt from domestic sewers and therefore continuous desilting of these drains is being carried out by deploying about 28 machines (Dragline -18 Nos., Hydraulic excavator water master-4 Nos with trucks, dozer, barges having total desilting capacity of 250 cum /hr though out the year. More machines are being purchased. Desilting also being carried out through contract where these machines can’t be deployed.
• Vasant Kunj, Mahipalpur and Dwarka area lack proper drainage system and suffered flooding. The I &FC with DDA, PWD, Airport authority, CISF, MCD, Metro rail, railways etc.is working on it to work out a comprehensive plan on sharing basis using STPs with covered drain of ultimate 1000 cusec capacity.
6.7.3. RAIN WATER HARVESTING Rain Water Harvesting is very old concept since ancient times and plays a key role in arresting floods and urban water scarcity. There are many ways of rain harvesting as illustrated below adopted by Delhi Govt which will go a long way in reducing urban floods. Construction of Tankas is another system of rain harvesting used particularly in villages where land in normally not costly.
A. On-channel storage of Rain Water in storm drains:
Rain Water is being impounded in 30 km length of Najafgarh (NG) Drain from Dhansa to Kakrola Regulator (by I &FC) by closing gates at Kakrola. 6.5 km of NG Drain has also been deepened impounding 155 MG water annually and further 2.3 km is proposed to be deepened by 1.5 m. the Mungeshpur drain has been regraded in 12.5 km impounding 4 MG water.
B. Artificial Recharge Trenches:
49 nos (cost aprox 1.0 lac each) in bed of Mungeshpur drain in North West Delhi in 7.3 km;
27 nos in borrow-area of Mundela Bund in 6.32 Km, 11 nos. in Khera Khurd storm water drain in 1.65 Km, 32 nos. in abandoned reach of Burari escape drain in 4.85 Km in consultation with Central Ground Water Authority (CGWA) have been provided. Similar trenches in other drains are also proposed to be provided.
C. Check Dam:
G Rain Water Harvesting Structures:
Buildings-bye laws have been modified to provide rain water harvesting in building plots more than 500 Sq. m in area including Roof top rain water harvesting. Some RWS`s are also voluntarily adopting this system in their colonies by good campaign of the Govt.
6.7.5 Flood-plain management :
The Yamuna Development Board, Yamuna Action plan-I, Yamuna Action plan- II and Usha Mehra committee etc are working for river Yamuna and its flood plains. A lot of JJ clusters and other structures along the banks and in the flood plains of river Yamuna have come up resulting in reduced flow. The High court of Delhi has constituted Usha Mehra committee to remove all encroachments up to 300m from water edge. This has resulted in removal of all JJ clusters and other structures reviving the original course and flood plain of river Yamuna.
It will definitely help in more flow and retention of water during floods. Under Yamuna Action Plan –II – A coordinated efforts are being made by all deptt and civic bodies for total Water Cycle Management of Delhi in relation to Yamuna and its flood plains.
6.7.6 Planting sturdy trees sustaining draught as well flooding: Stress has been given by The Govt Delhi for tree plantations where-ever land is available and particularly on road sides, along drains etc. Approx 5 lac trees are being planted every year. This will result in reducing soil erosion and run-off coefficient of the area and in turn reduce the flooding.
6.7.7 I&FC dept has started preparing of Master drainage plan of Delhi in consultation with all deptt of the govt. These data shall be properly documented and shall be used in planning and construction of drainage system of Delhi.
6.7.8 Land use and development planning
• DDA has been given responsibility to prepare master plans considering drainage aspects besides others for the development of the city. The DDA, MCD and the Delhi Urban Art Commission are responsibility to strictly follow the plans while developing the area.
• Certain area has been declared as reserved forests where construction of any kind is prohibited
• The land use and its planning in river New Yamuna is being looked by the DDA and supervised by the Central Water Commission, Delhi.
6.7.9 Suggestions of past expert committees on Delhi floods and drainage A Reddy Committee (1959): Recommended to remodel the drainage system of Delhi for an intensity of rain fall likely to occur once in two years i.e. for 42 mm/hr which gives discharge of 1.5 cusec /acre in urban area, @ 1.0 cusec/acre for city streets and 10 cusec /sq.mile for rural area. It was also suggested to review the drainage plan when future MPD is planned.
B Moti Ram Committee (1965): Recommended increased discharge capacity of Najafgarh drain to 10000 cusec C Jain committee (1968): Suggested preparation of Master plan of drainage of Delhi, c/o supplementary drain with discharge capacity of 4000 cusec to serve up coming urbanisation as per MPD 1961 D OP Goel Committee (1993): Suggested for coordinated efforts by all. Drainage problems having inter state ramification i.e. UP, Haryana, Rajasthan and Delhi needs to be resolved through central agency i.e. CWC. Open drains are suitable but for city like Delhi where land is a precious commodity, covering of drains may be think in certain areas where drain depth is more than say 1.5 m and available space can be used for road, parking or other commercial activities.
7.0 FLOODING MANAGEMENT- SAFETY TIPS
7.1 A By Government :-An Apex committee for flood –mitigation is working under the Chairmanship of the Hon’ble Chief Minister of Govt of Delhi with all ministers, MPs, some MLA and heads of all Govt /civic bodies looking after drainage, health, communication, food & supplies and dealing with basic amenities are its members with Chief Engineer ( I & FC) its member-secretary. Central control rooms are set up by MCD, NDMC, Police, Transport, Health, Home Guards & Civil Defence, Food & Civil Supplies, Flood Control Deptt., Delhi Development Authority, Education Department, PWD, Govt. of Delhi, BSES, NDPL, Delhi Jal Board and all connected to control room of CWC.
Guidelines on floods and complete information of nodal persons, arrangements, list of vulnerable points are issued as “Flood Control Orders” every year by the Divisional Commissioner of Delhi.
Flood control Department installs 25 wireless stations, one central control room connected with other city control systems of various deptt. Arrangement of flood materials like Empty Cement Bags-58500, Stone- 5714Cum, Ballies -2250, Boats-50, Life Buoy-211, Boat – Trolley-28, Boat Engine-24, Trucks-11, Life Jackets-471, Pumps-104 with pumping capacity of 330 cusecs, silt excavator machine -28 Nos and Motorola sets to all officers had been made to curb the Delhi floods.
The bench mark for alarming flood situation in Delhi is the water level of River Yamuna at Old Railway Bridge. The Warning level is 204.0 m and danger level is 204.83m. Warnings are also issued when discharge at Tajewala and Masani barrages are- FIRST Warning at one lakh and 35000 cusecs,SECOND at 3 lakh and 70000 cusecs, THIRD warning at 5 lakhs and one Lakh cusecs are released from these barrages. The warning level in Delhi has been attained every year except in 1987, 1991 and 2004.
B By Individual:
- Flood insurance policy for house should be procured. Have a disaster plan and prepare a disaster supplies kit for your home and car. Include a first aid kit, canned food, bottled water, battery-operated radio, flashlight, protective clothing and written instructions on how to turn off electricity, gas, and water.
7.2 During flooding:
This is on site measures require highest degree of efficiency and promptness. Some of them are illustrated here.
A By Government :- Evacuation priorities and needs, Identification of Evacuation sites, Evacuations during Un-expected flooding, Shelter management plan, Evacuation support plan, Live stock protections plan, Search and rescue of people and live stock, Setting up of Communications system, wireless system, control rooms, Health operation and first aid. Immediate relief measures like supply of food, water, essential commodities, evacuations of flood victims; plugging of breaches, protection and emergency repairs of public transport system etc.
Pumping out water from ponds, low lying areas, (the I&FC dept is having 205 pumps with 2250 HP and capacity aprox 330 cusecs which are used during flooding in any area allotted to it in Delhi). Total DJB’s Pumps-installations are 70 Nos. with capacity of 1000cusec.
B By Individual:
- Use sandbags or pillows or rugs to fill the airspace of a door during rising flooding, put the expensive things, electronic appliances, food and drinks upstairs or as high as possible, Switch off the power supply,Move to a safe and higher ground quickly. Be cautious at night, because it’s harder to see flood dangers. If told to evacuate, do so immediately. Avoid areas subject to sudden flooding like low spots or already flooded areas. Do not attempt to drive through a flooded road. The depth of the water is not obvious and the road may be washed away. Kids should never play around high water, storm drains or viaducts. Keep listening to the latest news and announcements from the police or local flood management team and obey instructions being given and cooperate and keep patience.
7.3 Flood measures after cessation of floods:
Restoration of power installation, public assets like road, railways, bridges, sewerage and water supply schemes and drains, merchandise and shopping areas, industries / factory equipments, public building, etc. Demarcation of land lines & removal of overlapping sand/Silt layer of flooded area are to be done. System of post-monsoon surveys needs to be done and corrective measures are adopted in time bound manner to avoid flooding in future.
Always boil drinking water. Electrical equipment should be checked and dried before used.
7.4 Failures of Flood Management Policies Floods may or may not occur regularly. The level, duration, extent and terming of their occurrence vary from event to event. Where flood occur after long intervals, (it may create immediate crises) memory of crises also fades away and so the preparedness of flood management also disappear.
Failure to adopt a comprehensive and effective flood management policy may be due to:Lack of adequate funds
2. Flood problems are technically complex and prediction of next occurrence is difficult.
3. Multiplicity of deptt/local authorities and Lack of coordination amongst these bodies.