Flood Management Plan for Dibrugarh Town

Client: Assam Climate Change Management Society (ACCMS)
Year: 2023
Location: Dibrugarh, Assam, India

A significant issue in Dibrugarh town is the unregulated expansion of urban areas, resulting in inadequate drainage systems. The challenges are exacerbated by excessive rainfall and improper land use, resulting in urban flooding.

The initiation of this study is to evaluate the flood risk (flood-prone regions), climate vulnerability, and develop short-term and long-term adaptation/resilience interventions in order to futureproof the town.

Objectives

  • To conduct risk and vulnerability assessment for Dibrugarh town (municipality) in terms of urban flooding with respect to climate change.
  • To develop a climate-resilient flood management plan for the town of Dibrugarh (municipality), proposing recommendations for climate adaptation/resilience encompassing blue-green interventions.
  • To develop a monitoring and evaluation framework along with describing the indicators that would be used to measure the overall progress of the project.

Potential Solutions

  • Implementation of Climate Resilient Blue-Green Infrastructure
  • Prioritizing interventions for the Dibrugarh Municipal Area, supplementing existing flood management programs
  • Sustained participation of Local Organizations and Community to support Local Government

Expected Outcome

  • Blue-Green Infrastructure interventions can reduce storm water runoff intensity form current 80% to 20%(approx.) attenuating peak runoff (Computed through Flood Modelling; Results Shared in the end)
  • BGI adds to urban environmental improvement introducing green spaces, natural ecosystems, and soft-engineering approach to longer term sustainability
  • Pilot list of interventions and locations to support process for receiving funding for implementation

Desk Research / Literature Review of Available Data

  • Historical analysis of flood, causes, issues and challenges occured, frequency of of flooding
  • Analysis of Master plan
  • Historical change in green cover
  • Climate change impact

Flood risk Assessment & Impact Mapping

  • GIS-based assessment Analysis of DEM for flood simulation modelling
  • Risk identification
  • Primary surveys of selected critical flood – prone areas in the city
  • Climate / Impact Modelling for Municipal-level Flood Risk Assessment

Climate / Impact Modelling for Municipal-level Flood Risk Assessment

  • Potential climate change impacts (future precipitation)
  • Time period feasibility:
    a. 2025 – 2039 (near future)
    b. 2070 – 2070 (far future)

Capacity Development of the Departments Involved
In Flood Management

  • Inception meeting
  • Consultation and capacity building workshop

Develop A Comprehensive Climate Resilience Plan For Dibrugarh Town Particularly From The Urban Flood Risk Mitigation Point Of View

  • Project Identification
  • Framework for measuring Dibrugarh’s resilience to climate change
  • Recommendations for short-term and long-term adaptation interventions
  • Develop a monitoring and evaluation framework

Site Visit

Historical Data

Past Flood Occurrences
Source:  An overview of Urban Flooding in Dibrugarh Town, Assam; Pal Arch’s Journal of Archaeology of Egypt / Egyptology  

Date

Affected Area

Consequences

Jun 10, 2015

The affected areas include Dibrujan, Durgabari, PWD Colony, Kalibari, Vishnu Nagar, Bagchipara, West Chowkidinghee, Bansbari, Amolapatty, Guardapara, Officer’s Colony, Nirmali Gaon and Police Reserve, Milannagar, Boiragimoth, Seujpur, Khalihamari, Gangapara, Lachit Nagar, Ambari, Kadamoni, Gandhi Nagar, Lichubari, Padum Nagar, Shantipara, Khania Gaon and Jibon Phukan Nagar

Shops and markets, schools and colleges, banks and offices have been remaining closed under the impact of the urban flooding

July 24, 2015

Flood water inundated Milanagar, Graham bazar, Khalihamari, KP Road,
Padum Nagar, Amolapatty, Naliapool, Santipra, Chowkidinghee, Gangapara, Bansbari, Gabharupathar and Seujpur areas

Drain water entered local houses; the city’s main roads were under water

Jul 1, 2016

Jibon Phukan Nagar, Bordoloi Avenue, Lachit Nagar, West Milanagar, Khaniagaon, Gangapara, Seujpur, Amolapatty, Padum Nagar, Naliapool, Santipara, KP Road, Durgabari, Vishnu Nagar, Khalihamari, Guardapara and Graham Bazar, Gabharupathar Police Station

Road damage, NH37 also affected. Drain water entered local houses

July 11, 2019

Prominent areas of the town, Traffic congestion, Road including, Thanacharali, Bagchipara, Chowkidinghee, Graham Bazaar, Santipara, locality next to Bagmibor Nilomoni Phukan, HS School and RKB Path

Traffic, Road damage

August 4, 2019

The road from Thana Chariali to Shankardev Hospital was affected

Traffic, Road damage

September 24, 2019

Gangapara, Bagchipara, Pathanpatty, Amolapatty, Graham Bazar, Seujpur, Naliapool, Boiragimoth, Kodomoni, Gandhinagar, Vishnunagar, Bhola Nath Road, Running Shed Gate, Milan Nagar, Santipara, West Chowkidinghee, Mollukubasa, Railway Colony, Police Reserve etc.

Normal life has been largely affected, unhygienic condition, traffic, road damage

Jun 25, 2020

Gangapara, Bagchipara, Pathanpatty, Amolapatty, Graham Bazar, Seujpur, Naliapool, Boiragimoth, Thanacharali, Chowkidinghee, Milannagar etc.

Traffic Problem, drain water entered local houses, health and hygiene problem, cocking problem, mental stress etc.

Workshop

Watershed

Watershed

Upstream zone

Midstream zone

Downstream zone

Total runoff (cu. m.)

Maijan

13,47,875

17,15,451

5,73,919

36,37,245

Sessa

59,13,356

93,83,587

16,66,098

1,69,63,041

Buri Dehing

1,28,36,277

1,02,42,890

31,84,929

2,62,64,096

Sub-basins in Planning Area

Sub-basin

Area (sq. km.)

Runoff Generated (m3)

Drain Capacity at 100% (m3)

Drain Capacity at 80% (m3)

Drain Name)

1

1.9

14,413

2

1.6

4,988

3

4.2

38,657

55,850

93,369

44,680

74,695

DTP

Rajabheta

4

5.3

85,577

1,09,022

87,217

DTP

5

2.8

19,699

85,004

68,003

DTP

6

4.7

63,171

7

5.5

47,175

71,220

56,976

DTP

8

2.4

17,758

28,795

23,036

DTP

9

1.7

4,974

10

15.9

3,44,861

95,610

76,488

Rajabheta

11

20

4,16,572

60,904

48,723

Rajabheta

Total

10,57,851

5,99,777

4,79,821

Flood Prone Areas
  • Around 31 sq.km. area out of 71 sq.km. (planning area) is flood prone
  • Many low-lying areas are found underwater logging within the city area.
  • Due to the absence of stormwater drains, the rainwater and the flash water, in monsoon, are unable to flow downstream, and this area becomes prone to waterlogging.
  • At many places, the accessibility of on pavement is hindered due to water logging and hence sometimes become a reason for traffic congestion.
  • The waterlogged areas include Mancotta and NH-37 T-junction to Civil Defence Office; near the office of Divisional Forest Officer to the cross-junction of NH 37 (AT Road) to Dibrugarh Hospital (civil hospital).

Wetland

Identified Wetland Suitable Locations in Dibrugarh

Identified Wetland Suitable locations in Master Plan Boundary

The nature-based solutions are proposed on the following scales of urban extent

The City Scale

  • Urban forests and terracing on higher elevation levels to delay runoff.
  • Creation of constructed wetlands or wetland restoration in lower urban areas to collect and store water runoff.
  • Renaturation of existing streams and drainage lines in the city to slow down water flows.
  • Increase of open green spaces or parks throughout the city to add infiltration capacity and reduce urban heat.
  • Continuity of linear tree canopies and green corridors along roads in the city.

The Neighborhood / Building Scale

  • NBS integrated into buildings such as green roofs, green facades, private gardens in combination with green streets. Such measures can both regulate temperature and store water.
  • Retention basins, rainwater retention ponds, or green water squares to store water.
  • Small-scale rainwater catchment and drainage interventions such as bioswales.