Disaster and Floodplain Management: DRTMC, University of Dhaka Climate Change and Sustainable Floodplain Management Dr. K. B. Sajjadur Rasheed Former Professor of Geography and Environment, University of Dhaka Adjunct Faculty, Independent University, Bangladesh and Consultant, Center for Environmental & Geographic Information Services

Prologue 20 th century’s biggest challenge is climate change and its biggest threat is to ‘environment’ and ‘sustainable development’ Floodplains are a dynamic landscape: their forms and features are continually changing; hence, sustainability is a major goal

Climate Change Impacts and Projections Observed impacts: Atmospheric warming is unequivocal Each of the last three decades has been successively warmer than any decade since 1850 Over the past two/three decades, glaciers and ice sheets have continued to shrink Between 1993 and 2010, mean annual sea level rise [globally] was 3.2 mm

continued Projected impacts: Continued emission of GHGs will cause further warming, and is likely to exceed 2 o C by 2100 Virtually certain that there will be more heat waves Monsoon precipitation: likely to increase Monsoon retreat dates: likely to be delayed By 2100, global glacier volume likely to decrease by 15 to 85 percent SLR – likely to be up to 0.82 meters with no mitigation; and will continue beyond 2100

Significance in BD ecosystem Higher temp means more moisture from BoB; more rain internally & in India/Nepal/Bhutan; more water volume in GBM rivers; and higher frequency of floods Forms & features of floodplains will undergo continuous changes; due to floods [area, depth, duration], bank erosion and high intensity rain

continued  Adverse impacts on floodplain livelihoods:  Farmland submergence: crop loss  Prolonged drought: land degradation  Delayed monsoon retreat: threat to Kharif II (T. aman) and Boro crops  Salinity in coastal zone: crop loss  Loss to fisheries sector from flooding  Biodiversity health: trees and species habitat

What is ‘sustainability’ in floodplain management? Use & maintaining floodplain ecosystem over the generations Floodplain is dynamic: changes in it are intensified from climate change impacts Soils are reformatted; drainage is altered; farmlands are reclassified; settlements and other infrastructure are relocated due to floods and bank erosion Task: efforts to contain damage and retain basic potentials for farming, fishing & settlements Objective is to make floodplains capable to meet the needs of growing population for more crops, more homesteads, more fisheries, more biodiversity etc.

Response Strategy and Options for Floodplain Management

Adaptation and Disaster Risk Reduction Adaptation: seeks to make adjustments in natural and human systems to impacts caused or will be caused by climate change: [autonomous or planned] DRR: efforts to reduce damage through mitigating disaster effects AND preparedness to meet the challenge

continued Both adaptation and DRR should go in tandem since climate change related hazards are going to be more frequent and intensive; and DRR can help in (a) preventing or avoiding, (b) minimizing losses; and (c) recovery Preparedness under DRR strategy is a major instrument for sustainability of floodplains

continued Response planning in Bangladesh National Adaptation Program of Action [NAPA]: 2009 ( updated version of 2005) Bangladesh Climate Change Strategy and Action Plan [BCCSAP]: 2009  Both documents address problems of livelihood security and sustainability for floodplains, where most people live

continued Both documents (especially BCCSAP) emphasize measures for floodplain ecosystem, such as (a) innovative crop technology with climate- resilient crops; (b) diversification of fish culture techniques; (c) strengthening flood and cyclone warning systems; and (d) repair, rehabilitate existing embankments and plan, design & construct new hazard mitigation structures like river embankment, coastal embankments, and drainage systems etc.

Measures to ensure floodplain sustainability Principal objective is to enhance the resilience of floodplains to face: increased rainfall & flooding and more volume of upstream water; management of channel siltation, bank erosion; soil salinization; land degradation from drought; vulnerability of settlements & infrastructure from inundation

Embankments River and coastal embankments, despite many criticisms, are sine qua non to protect lives, assets in floodplains No possibility of moving setback distance further inland to accommodate water in the channel To accommodate increased water volume in rivers, embankment heights need to be raised up to 1.5 m, including coastal embankments (to prevent surge)

Embankments cont BD has more than 8,000 km of embankments, many in bad shape due to lack of maintenance (and encroachment) Floodplains will not be sustainable if embankments are not sustainable Hence, prime concern is monitoring and management of embankments, including installation and operation of more sluice gates to drain country-side water from increased rainfall

Behavioral modification of rivers Channel improvement: (more rigorously) (a)Dredging in prime sections including around infrastructures & settlements (b)River channel straightening thru’ loop cutting, bypass, local structural control (c)Groynes and spurs on river banks to deflect floodwater and minimize bank erosion The purpose is to enhance river’s conveyance capacity, and control its flow in a planned manner

Flood preparedness Flood forecasting and warning is the most cost- effective tool for minimizing losses from floods South Asian monsoon changes will affect flooding in BD Hence, flood forecasting needs to be strengthened More upstream data should come from India, Nepal as well as China Regional information exchange among GBM countries on flood management measures

Climate-smart cropping Objective: to attain sustainability in floodplains thru’ addressing climate change challenge Crop diversification: to adapt to ecological changes and prevent total crop failure from floods, drought & unseasonable rainfall Expansion of hybrid rice cultivation to take advantage of shorter growing period and high productivity Climate resilient rice crop innovation (new species): salt tolerant (for coastal region); submergence tolerant (for flood prone central BD); and drought tolerant (for drought prone northwestern BD)

Coastal floodplains Problems ahead: sea level rise in the Bay; salt water ingress in soil, surface and ground water; more intense cyclones and stronger surge; coastal erosion = then, what to do for the coastal plain? Raising polder and embankment heights to prevent sea water from entering inland farms & settlements Expansion of coastal afforestation and ‘green belt’ all along the coastline Introduction of salt resistant/tolerant rice and other crops to offset increased soil and water salinity

continued Promotion of alternate livelihoods: brackish water fisheries in lands unfit for crop agriculture; expansion of shrimp farming (with effective environmental safeguards) Cross dams between chars/mudflats to prevent coastal & riverine erosion, and accelerate accretion (for land reclamation) Sea wall or dykes to protect coastal ports, towns, & other infrastructure (true it is expensive, but selectively needed as essential option)

Summing up Floodplain is created by natural forces in river basins, yet, another natural force: ‘climate change’ (caused by human actions) is threatening its sustainability. ‘Do nothing’ is no more an option Actions to attain floodplain sustainability must be proactive, with active participation of floodplain users and managers: with both structural and non- structural options should be explored and used Vision: Synergy between planned and autonomous adaptation by floodplain managers (including planners & administrators) and floodplain users or inhabitants

Thank you all for your attention