Watershed ppt (Final)

Municipal Corporation of

Greater Mumbai, India

Managing Mithi Drainage Basin

To Enhance Flood

Resiliency

Mumbai Topography and Drainage

Merger of 7 islands in Island City, 4

islands in Suburban District.

Surrounded by water on three sides.

Much of the area is close to sea level.

Gravity drainage system affected by

high/low tides.

During high tide ingress of sea water.

Island City has no natural drainage

outlet.

Mithi largest river flowing in Suburban

District

Catchment area 7265 hectares

Length approx. 17.9 km

Storm Water Drainage Network is

more than 150 years old designed for

rainfall of 25 mm per hour and run off

co-efficient of 0.5.

Rainfall Characteristics

Watershed degradation

Inadequate Storm Water

Drainage System

Increase in Impermeable

Surface Cover

944 mm in 24 hrs.944 mm in 24 hrs.On 26On 26thth July 2005July 2005

Vulnerability of MUMBAI

To Flooding

Urbanisation has increased vulnerability of

Mumbai to floods

Narrowing of banks for housing and slums

Reclamation of river beds by industrial units

Diversion of course of the river for construction of the

airport

Main river has been forced to turn 900 four times in

quick succession.

Some sections are bunded with walls and

embankments on both sides.

Reclamation of natural ponds

Reclamation of mangroves for construction of Bandra

Kurla complex.

Moraraji Nagar Slum EncroachmentMoraraji Nagar Slum Encroachment

Mithi on Kurla Mithi on Kurla Saki Naka RoadSaki Naka Road

Land use changes have increased

vulnerability of Mumbai to floods

Change in land use pattern has led to an increase in

run off coefficient to almost 1.0

Mithi River Flooding Mithi River Flooding 2626thth July 2005July 2005

Recommendation: Do not obstruct water flow of the

river

Initiatives taken since 2006

Widening & deepening of Mithi River is almost completed

940,406 cubic meters of silt and 492,000 cubic meters of hard rock

has been excavated from the river bed till 31st March 2011

Construction of R.C.C. retaining wall of 7.8 km length on both the

banks along with 6 to 12 mtr wide service roads.

Two weirs have been completed along the river.

4922 (residential & non residential) structures have been

demolished for widening the river, 663 structures remain to be

demolished

Expenditure incurred till 31st March 2011 69.8 Million Euros

Expected expenditure to complete the remaining work approx 71

Million Euros

Target date of completion December 2012

SAKINAKASAKINAKA

Weir Wall at BamandayaWeir Wall at Bamandaya

New Bridge At Kranti Nagar

Upstream of Kranti Nagar Bridge

Before

Upstream of Kranti Nagar Bridge

After

BEFORE

AFTER

Recommendation: Develop Early Warning Systems

Installation of 35 automatic

weather stations at 28 locations

Console gives audible alarm

when the rainfall exceeds 10mm

in 15 minutes

Rainfall data is transmitted every

15 minutes to the EOC, MCGM

Flow Gauges have been installed

upstream of Mithi River and a

measuring scale has been marked

on the existing pier of

Krantinagar Bridge to indicate the

level of water in the Mithi river

and issue warning to the

population living downstream20

KRANTINAGAR

FLOODING SPOTS

CATCHMENT

BOUNDRY

IRLA PUMPING

IRLA NALLA

IRLA NALLA Br-A

IRLA NALLA Br-BGARWARE NALLA

IRLA NALLA Br-C

Recommendation: Augment the capacity of the storm water drainage system to cater to the increase in runoff

ABHISHEK NALLA

Nalla training work

completed Work under SRA

development

FLOODING SPOTS

1 Milan Subway

2 VM Road

3 Near Cooper Hospital

4 JVPD Area

5 Near Vile Parle Station

6 Sahar Road Junction

1

2

3

4

5

6

Work of training yet to

start (funded by

MCGM)

Work of training under

progress

Existing Trained

KOLE DUNGARI NALLA

Pumping Stations

Storm Water Pumping Station at Irla

Capacity 48 Cubic Meter / Second

No. of Pumps 8

Capacity of each pump 6 Cubic Meter / Second

Progress Inlet channel - Irla

Progress Irla

Recommendation: Prepare detailed Contour Maps to

identify the sub-catchment and low lying areas

A contour map of Mumbai with 0.2 m interval has been

completed

Recommendations

Conserve wet lands

The reclamation of mangroves

for construction of the

Bandra Kurla complex has

increased the likelihood of

flooding.

Promote recreational

activities along the banks

of the river

GOALS OF DRMMP

Recommendation: Preparation of a comprehensive

Disaster Risk Management Master Plan

Policy Recommendations

Make flood risk and flood hazard

assessments an integral part of the

master planning process

Record construction details along with

the plinth and ground level in a master

inventory

Provide flood-resistant temporary

shelters

Municipal Corporation Of Greater Mumbai

Thank You

Making Mumbai a better and safe place to live in