Protecting the coastal polders

Till mid-1980s the policy on management of polders remained focused on agriculture and dictated by the imperatives of attaining self-sufficiency in food with little or no regard to erosion. The severe floods in 1987 and 1988 triggered the need for erosion control. The government with international supports promptly formulated a Flood Action Plan (FAP) that comprised 26 structural and non-structural interventions. The Master Plan of 1964 recommended implementation of 59 FCD/I projects but specifically neither included any erosion control measures nor indicated any strategy therein and, thus the coastal polders were left at the vagaries of nature for continuing erosion. Since 1972 the two major international donors that supported 46 FCD/I projects at a cost close to US $ 1800 million included nothing substantial on erosion control.

The basic physical parameters for estuarine erosion are river discharge varying with hydrograph, sediment discharge varying with channel geometry, bed and bank material and, length and slope of the channel. System carrying the sediments is subjected to a process generated by hydro-dynamics, responsible for the morphological changes correspondingly resulting erosion and accretion. The most important environmental factor impacting the coastal polders is this erosion. The partial information reveals that during the period from 1982-1992 about 106,300 ha were lost due to erosion along the major rivers while only 19,300 ha were accreted. The net area of 87,000 ha gobbled is mostly agricultural lands. The rolling displacement of population has been estimated at 64,000. Based on these rates the nation during last 30 years probably has lost over 300,000 ha of productive lands and rolling displacement of more than 200,000 people including damages to water infrastructures.

Impacts of erosion are eventually translated into enormous vulnerabilities raising challenges the nation has to face in realising benefits from its development programmes. Erosion causes affected people suffer emotionally by the fact that they loose not only an important production asset but also suffer the loss of their status in the community that the land holding and the asset provide. Infrastructures damaged by estuarine erosion make the polders immediately partially or fully non-functional thus severely impacting its management. The vulnerabilities stemming from the erosion makes the public and private development efforts continuously repetitive, distract community interests and cause readily unsustainable, mounting pressures on national initiatives.

Management of polders is also vulnerable to continuing coastal and estuarine erosion and accretion process. Inappropriate setting of the institution involving stakeholders' participation and inter-agency co-ordination is the major impediment towards integration and harmonisation of the management of the coastal polders culminating in sub-optimal use of the coastal resources. Most of the FCD projects in the coast as such have failed to perform as effectively as originally conceived and designed. Besides, the salt-water irrigation for cultivation of salt and shrimp has all the way been ignored by the water-professionals.

Salt-water irrigation instead of salt-water intrusion has in many cases reversed the traditional coastal water management. The mode of operations and functions of the hydraulic structures regulating water have also been reversed by way of introducing the salt-water within the project instead of preventing the saline-water intrusion from the sea; thereby impacting the planning and design. The gradual depletion of the coastal ecology has drawn attention of the experts for its repletion in the recent years.

The coastal phenomenon inclusive of regular astronomical tides, soil salinity, salt-water intrusion, erosion and accretion, sand blowing, mining, storm surges, cyclones, and the other coastal vulnerabilities have been impacting the management of polders in the coast. Estuarine erosions and other coastal phenomenon have combined impacts on the management of coastal polders in achieving its desired objectives. Options for reduction of impacts on management are complicated involving the limitation of resources, adherence of priority to technical stability of the infrastructures, multi-dimensional vulnerability, stakeholders' participation, institutional settling, inter-governmental organisations co-ordination, public-private partnership, climate change, micro and macro-level economy, and eventually the socio-political commitments towards a sustainable management of coastal polders. The management of the coastal polders should be transferred to the stakeholders where local government institution may play the pivotal role in reduction of the impacts.

Md. Saeedur Rahman, is Chief Engineer, Bangladesh Water Development Board.