Urban Flooding: Causes and Management

Disaster Management”, from 27th -29th October 2009

Dr. N. Sai Bhaskar Reddy, CEO, GEOhttp://www.e-geo.orgsaibhaskarnakka@gmail.com

Rajendranagar, Hyderabad

What Happened ?• Andhra Pradesh recently has been hit by a devastating flood. 30th

Sep-6thOct 2009• The most affected districts in Andhra Pradesh are Kurnool,

Krishna, Guntur, Nalgonda and Mahaboobnagar. • Over 1.3 million people are displaced from their homes. The

official death toll is 199 people with 6,295 livestock that have also perished in the six districts.

• As many as 478 villages in 87 mandals have been severely hit in the last four days with the heaviest flooding that River Krishna has seen in more than a 100 years.

• 42,000 houses in Kurnool and 11,680 houses in MahaboobnagarGuntur District are severely affected.

• Millions of acres of agriculture which include paddy, cotton, turmeric, maize, chilly and many other commercial crops are also damaged.

Imageries

10/6/2009 North America Telugu Society Inc. (NATS)

SriSailam Project and Nagarjuna Sagar

Krishna River

Krishna River Vijayawada

Photo Gallery

Photo Gallery

Photo Gallery

Photo Gallery

Photo Gallery

Types and causes of floods3.0 TYPES OF FLOODING3.1 According to Duration Slow-Onset Flooding, Rapid-Onset Flooding, Flash Flooding.3.2 According to Location Coastal Flooding, Arroyos Flooding, River Flooding and UrbanFlooding. The urban area is paved with roads etc and the discharge of heavy rain can’tabsorbed into the ground due to drainage constraints leads to flooding of streets,underpasses, low lying areas and storm drains.4.0 CAUSES OF URBAN FLOODING4.1 Natural Causes4.1.1 Heavy Rainfall / Flash floods Water of Heavy rainfall concentrates and flows quicklythrough urban paved area and impounded in to low lying area raising the water level. It createsmore havoc when a main drain or a river passing through the area over-flows or breaches4.1.2 Lack of Lakes Lakes can store the excess water and regulate the flow of water.When lakes become smaller, their ability to regulate the flow become less and hence flooding.4.1.3 Silting The drains carry large amounts of sediments and deposited in the lowercourses making beds shallower thus channel capacity is reduced. When there is heavy rain, thesesilted drains can’t carry full discharge and result in flooding.

4.2 Human Causes4.2.1 Population pressure Because of large amount of people, more materials are

needed,like wood, land, food, etc. This aggravates overgrazing, over cultivation and soil erosion

whichincreases the risk of flooding.4.2.2 Deforestation Large areas of forests near the rivers/catchment of cities are

used tomake rooms for settlements, roads and farmlands and is being cleared due to which

soil is quicklylost to drains. This raises the drain bed causing overflow and in turn urban flooding.4.2.3 Trespassing on water storm drains The areas which were essentially created bythe storm water drains to let their flood waters pass freely being tress-passed for

developmentalpurposes result in obstruction of water flow and thus contributed immensely to the

fury of floods.

4.2.4 Urbanisation leads to paving of surfaces which decreases ground absorption andincreases the speed and amount of surface flow. The water rushes down suddenly into the streamsfrom their catchment areas leading to a sudden rise in water level and flash floods. Unplannedurbanisation is the key cause of urban flooding. Various kinds of depression and low lyingareas near or around the cities which were act as cushions and flood absorbers are gradually filledup and built upon due to urbanisation pressure. This results in inadequate channel capacity causingurban flooding.4.2.5 Un Authorised colonies have been developed by the local colonisers onthe agriculture land, earlier being used for crop has been purchased at lucrative prices fromfarmers, without consideration to the city plans ,drainage, sewerage etc. and thus subjected toflooding during heavy rain falls.4.2.6 Poor Water and Sewerage Management Old drainage and sewerage system hasnot been overhauled nor is it adequate now .All the drainage and sewer system in many parts ofDelhi has collapsed resulting in flooding. This can be seen during rainy seasons every year.4.2.7 Lack of attention to the nature of hydrological system.4.2.8 Lack of flood control measures.4.2.9 Multiple authorities in a city but owning responsibility by none.

CAUSE OF FLOODS

Impacts • - loss of human life• - flooding of housing, commercial and industrial properties• - flooding of streets, intersections and transportation systems, causing traffic delays• - recurring basement backups from surcharged sanitary sewers• - inflow of stormwater into sanitary sewers• - municipal waste water treatment plant by-passing• - combined sewer overflows• - spilling the surcharged sewers content into streets• - damage to public and personal property• - health hazards• - disruption of services such as water supply, sewerage and power supply• - delays in public transportation• - cleanup demands• - adverse effects upon the aesthetics• - disturbance of wildlife habitats• - economic losses• - pollution of local waterways and receiving water bodies

Flood Management Planning• - reducing exposure of people and property to flood hazards• - reducing existing level of flood damages• - minimising soil erosion and sedimentation problems• - protecting environmental quality and well-being by reducing in-the-catchment

pollution• - improving the usefulness of floodplains• - minimising receiving water pollution• - reducing future after-development flow rates to pre-development levels• - enhancing recreational opportunities and improving overall urban amenities• - replenishing ground water• - supplementing domestic water supply• - capturing water for irrigation• - protecting public health• - providing open space and parklands• - using stormwater as a resource

• Godavari, most severe recorded flood, in 1986, lasted for 20 days

Godavari Floods August 2000• Hyderabad, Aug 28: THe Godavari river was in spate and rising rapidly all along its course in

Andhra Pradesh today, posing a flood threat to five districts even as the state government was grappling with last week's havoc wrought by floods that had claimed 141 lives.

• low-lying areas in Karimnagar, Warangal, Adilabad, Khammam and Nizamabad were being evacuated and the district administration had been put on alert to take up rescue and relief operations. Following heavy rains in catchment areas of Pranhita in Maharashtra, Godavari level was rising rapidly all along its course from Nanded to Dowleshwaram in east Godavari districts, he said.

• The Godavari basin districts had received a record 42 cm rainfall since Sunday triggering a flood threat to Karimnagar, Adilabad, Warangal, Khammam and Nizamabad districts.

• The flood water entered 23 island villages in west Godavari district while the famous Kolleru lake in the district was in spate inundating one lakh hectares of paddy crop.

• In the last week's floods, 141 people had died and over 3,090 villages, spread over 13 districts, were affected with 298 villages being totally marooned. Over 54,000 houses and 12,247 roads were damaged and the preliminary estimation of losses to public property was put at Rs 776 crore.

For regulating flood plain use:- zoning ordinances- floodplain regulation- waste disposal regulation- groundwater quality protection regulation- subdivision ordinances- building ordinances- reduction of population densities- regulation of squatter settlement in flood prone areas- prohibiting specific functions of land- relocating elements that block the floodway- regulating the building material- providing escape routes to higher places- state regulated and sponsored insurance policy

Management

• Community based disaster preparedness programs

TASK FORCE TEAMS

FIRST AID SHELTER MANAGEMENT RELIEF

RESCUEWARNING

DM COMMITTEE

CBOs – SELF-HELP GROUPS, ETC.

WARD / GRAM PANCHAYAT

DM SOCIETY at Municipality

DM COMMITTEE DM COMMITTEE DM COMMITTEEDM COMMITTEE

DM COMMITTEE DM COMMITTEE DM COMMITTEEDM COMMITTEE

DMCs of each area

HEALTH

ENGINEERLAW AND ORDER

MRO / MDO AGRICULTURE

DISTRICT COLLECTOR / JOINT COLLECTOR / CEO

MPTC / ZPTC

Municipal Corporation

DISTRICT DISASTER MANAGEMENT

CELL / TASK FORCE / RELIEF AND

REHABILITATION CELL

MP / MLAZP CHAIRPERSON

Departments

RDO / SUB-COLLECTOR

PUBLIC / PVT / NGO

The Disaster Management Bill, 2005 Disaster Management Act, 2005The National Disaster Management Authority National Disaster Response Force

State Disaster Management Authority

District Disaster Management Authority

DMC / DMS Organisational Structure (Suggested)

Pre flood activities• Conducting meeting in the villageS / Wards regarding the

possible extent of flood and actions to be taken.• Checking of all rescue material. i.e.- bottles, coconut,

ropes, thermocoal boats, etc• Early warning group preparation• Identification of old people, pregnant ladies, kids• Identification of high raised place• Rice collected from all households• First aid material made ready• Radio / TV news by warning groups

During flood activities• Announcement in the village• Evacuation to safer place to old age people, ladies, kids,

sick people & live stock• Moved people to safer place (i.e. aged people, pregnant

women, children, sick people etc…)• Arrangement for temporary shelter• Approached Govt. for emergency relief• Availed rice and dal from Government for camp.• Use high raised bore well for drinking water• Monitor the Water levels and receding status.

Post flood activities• Flood Area survey• House damage survey• Water logging sites survey• Call to govt. medical team for medication• Cleaning of Debris and cleaning whole Village.• Bleaching powder spreading in water and logging areas• House damage assessment• Crop damage assessment (both the reports were given to the govt officials,

they were so amazed to see that how accurately it has been done. Further the compensation and new houses were sectioned according to this assessment.

• Relief from Govt. & NGOs distributed through DMC & Task force • Govt. Relief distributed equally in the village• Sick people were taken to hospital

SOCIAL

SOCIAL

ACCESS TO HEALTH

SERVICES

LOCAL INSTITUTIONS

DISASTER MANAGEMENT

COMMITTEE

TASK FORCE

ROLE OF GRAM

PANCHAYAT

VILLAGEPOPULATION AND %AGE OF VULNERABLE AGE GROUP

POVERTY OF THE

HOUSEHOLDS

INSTITUTIONAL

BUILDING

HUMAN

TRAINING

AWARENESS

COMMUNICATION

LOCAL SPECIFIC

INDIGENOUS KNOWLEDG

E

NETWORKING

SENSITIZATION

KNOWLEDGE AND SKILLS

KNOWLEDGE /

UNDERSTANDING

PHYSICAL

ROADS AND COMMUNICATION AND WARNING SYSTEMS INFORMATION

RELIEF CENTERS: HIGH REACH AREAS AND SHELTERS (SCHOOLS / COMMUNITY CENTERS / RELIGIOUS PLACES, ETC.)

FOOD / COOKING NEEDS, LIGHTING

AND OTHER ESSENTIALS

LIFE SAVING EQUIPMENT BOATS / LIFE JACKETS / ETC.

INFLUENCE OF SCHEMESAND PROGRAMME /

GRANTS OR SUBSIDIES

ACCESS TO PUCCA HOUSES / RAISED BOREWELLS

FISHERIES, MICRO-

ENTERPRISES, ETC.

ACCESS TO CPR AND

MANAGEMENT

NATURAL

AGRICULTURE

CHOICE OF CROP AND

SHORT DURATION

LIVESTOCK

LAND DEVELOPMENT

AND ACCESS TO IRRIGATION

INPUT, PRACTICES AND OUTPUT

SUPPORT

ENVIRONMENTAL

FLOODS OCCURANCE AND

INTENSITY

DROUGHT OCCURANCE AND

INTENSITY

CLIMATE VARIABILITY FACTORS

FINANCIAL

DMCVULNERABILITY

REDUCTION FUND (VRF)

SHGsMICRO-FINANCE

SOCIO-ECONOMIC PROFILE OF COMMUNITY

ACCESS TO LOANS FROM

BANKS

SUPPORT ORGANISATIONS

PROJECTS / PROGRAMMES /

RELIEFCOMPENSATION / GRANT /

RELIEF AND REHABILITATION SUPPORT FROM GOVT. AND OTHER

AGENCIES

Policy • The Government of India, initiated the following measures related to disasters management:• The Disaster Management Bill, was passed in 2005 • Disaster Management Act, came into existence in 2005• The National Disaster Management Authority was formed• National Disaster Response Force is also formed

• Provided facilities for formation of State Disaster Management Authority, District Disaster Management Authority and local authorities.

• The Disaster Management Unit of Andhra Pradesh under the Ministry of Finance, initially would be involved in the following activities:

– formation of a long-term mitigation policy– undertaking key hazard studies– restoring and strengthening infrastructure with improved design– use of innovative methods such as the setting up of the Vulnerability Reduction Fund Trust– improved methods of capacity building through innovative training and orientation programmes and

community participation– extensive use of mass media and multimedia.

District level

Sr. No Long term Sr. No Short term

01 Infrastructure 01 District task force Relief and Rescue operations

02 Embankments 02 Compensation

03 Communication

04 Relief funds

05 Road

06 Housing

Short term and long term measures by Govt., Institutions, organizations and community at different levels anticipated as such.

MANDAL/ FEDERATION LEVELSr. No Long term Sr. No Short term

01 Hostel 01 Seeds Provision

02 Education 02 Land reclamation

03 School provision 03 Fertilized Provision

04 SC/ST Welfare hostel 04 Evacuation relief and rehab. centres

05 Vocational training center

06 Loan access to bank and institutions

07 Marketing centers

08 Early warning systems & Awareness

VILLAGE / HABITATION / WARD LEVELSr. No Long term Sr. No Short term

01 PHC 01 First aid / health care camp02 Relief- rice, pulses, clothing,

vegetables, kerosene, blankets, buckets, plates, mugs, mats

03 Boat 03 Temporary shelters04 Rescue materials- Net, life jacket,

mega phone04 Compansation

05 Radio06 Micro finance and enterprises07 Village roads08 Sanitation09 Potable water10 High raised bore wells11 Housing12 Identification & shelter

ReferencesNorth America Telugu Society Inc. (NATS)