5.1Introduction -
From the environmental safeguard view point, an alternative analysis is an important tool for the best selection of the project, implementation process, and operation mechanism in terms of environmental acceptability of the chosen method. Alternative analysis provides information about the advantages and disadvantages, quantifies the environmental impacts to the extent possible, and attaches economic values where feasible for each alternative considered. The alternative analysis for CEIP project will be conducted into two phases.
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Phase 1 will analyze the "no action" alternative of the project which will be reflected in this document and during embankment specific environmental assessment.
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Detail activities to be carried out for implementing the proposed interventions will depend on the design of the interventions. Phase 2 will conduct embankment specific alternative analysis for the project design, technical options, and implementation and operation method in terms of environmental impact. The second phase analysis will be conducted separately for each of the embankment and will be reflected in the Environmental Impact Assessment and Initial Environmental Examination report.
5.2No Action Alternative -
No Action Alternative means the future socioeconomic and environmental scenario of the area without any development in the coastal polder. This section presents the predicted status of the area without the project in the coastal areas considering the climate change and its impact.
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Coastal area of Bangladesh is already vulnerable to natural hazards. It is expected that climate change will have further impact on the characteristics of the hazards such as cyclone and storm surges, tidal flooding and drainage congestion due to sea level rise (GoB, 2009). The existing structures of coastal polders are currently not functioning well in most areas. Baseline data of polders show that the existing crest level of the embankments is below the design level due to subsidence and top soil erosion. Analysis of the capacity of existing polders to withstand storm surge with climate change scenarios, carried out by IWM under current feasibility study of CEIP project, shows that most of the coastal polders will be overtopped by storm surge with return period of 25 year – 100 year. Some of the embankments can prevent only storm surge level with 10 year return period. Also, recent study shows that 14 interior polders and 30 sea-facing polders are likely to be overtopped by storm surge under the baseline scenario (2005) (Figure 5.1). The extent of overtopping in these polders increases under the climate change scenario for 2050 (with 27 cm sea level rise). Under the climate change scenario, 12 additional interior polders and 3 additional sea-facing polders may be overtopped (World Bank, 2010). Most of these polders are located in the Ganges Tidal Plain East (GTPE) zone in the coast area. A list of the polders likely to be overtopped is given in Appendix – 5.
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As embankment were originally designed to protect against high tide without consideration of storm surges, without an upgrading of the embankment system, most coastal poldes are at risk from flooding from storm surges. Increasing the crest level of the embankment and widening their slopes through CEIP project will help to protect people living inside the polder (along with their asset) from storm surges, which are likely to worsen with the impact of climate change.
 
Figure 5 14: Overtopped Polders in Coastal Area Under Different Scenarios (World Bank, 2010)
5.2.2Salinity Intrusion -
Saline water intrusion is an important issue in coastal area and is very much related to climate change induced sea level rise. Depending on temporal and spatial variations, salinity affects the coastal ecosystem, fisheries, agriculture and public health. IWM and CEGIS (2007) estimated that more coastal area will be affected by high salinity due to future sea level rise than present saline affected areas. It is found that 1 ppt salinity line may move towards upstream by 10km to 20 km during monsoon, mainly in the central part (through Baleswar-Buriswar rivers) due to 27cm sea level rise and 62 cm sea level rise respectively. In Hatya and Manpura island in the Meghna Estuary, maximum salinity level may be increased to 3-5ppt for 27cm (in 2050) and 62cm (in 2080) sea level rise respectively (IWM and CEGIS, 2007) (Figure 5.2).
Figure 5 15: Salinity Condition In Coastal Area (for 2005 and 2050)
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For the improved drainage system, or protection of saline water intrusion by embankment and water control structures through CEIP, the salinity problem will be reduced in the project area. With proposed implementation work of retirement of embankment and replacement and new construction of water control structures, saline intrusion in khals, ponds water and other surface water sources will be prevented. Salinity will also be decreased due to flushing during wet season.
5.2.3Drainage Congestion and Water Logging -
Most of the internal khals are silted up and drainage and flushing sluices of the polder are not functioning properly which is a major reason of water logging/ drainage congestion in polder areas. If the present situation continues, the polder area will face more drainage congestion due to malfunctioning of water control structures and the continuous siltation in the internal khals. Especially drainage system will collapse if the regulators and flushing sluices remain in its damaged condition. After implementation of the proposed structural works, the drainage congestion would improve inside the project area. The project rehabilitation interventions, replacement of all regulators and flushing sluices with adequate vents and construction of new flushing sluices would significantly remove the drainage congestion and water logging problems in the polder areas.
5.2.4Surface Water Availability -
Availability of surface water would be reduced in ponds and other wet land areas, if there will be no initiatives to store water in internal khals by making the regulators functional. Due to unavailable upstream fresh water flow in some rivers like Bhairab-Bishnu and climate change induced changing rainfall pattern in South-west area of Bangladesh may create drought. Ground water table would also be depleted due to low rainfall or shifting of rainfall pattern and abstraction of excess ground water during dry season. Reserves of surface water for irrigation would be reduced due to silted up khals and malfunctioning of water control structures. With the implementation of the project, surface water availability is expected to be significantly improved when drainage system and water controlling structures will be implemented. After replacement and construction of new regulators with adequate vents, fresh surface water will be restored extensively in the internal khals and facilitate supply of irrigation water as well as recharge of ground water table.
5.2.5Sedimentation -
Presently, tidal inflow causes sedimentation in rivers and khal beds and also in the tidal creeks. A number of important khals of the project area have been silted up through the Surroundings Rivers. This rate will increase if the water control structures are not replaced. This massive sedimentation will reduce depth of the rivers and internal khals which will increase drainage problem and tidal wave action. Thus overtopping the embankment will be more frequent that will increase flood plain area of the polder, of proper action is not taken. Proposed interventions of structural and embankment works will reduce the sedimentation rate of the defined channels and will make the internal drainage system more active. Sedimentation will be reduced and tidal influence will increase after the structures with adequate vents are replaced and the embankment is strengthened as per implementation plan. The increased tidal prism will increase bed scouring in khals and rivers bed for smooth drainage of the polder area.
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Soil nutrient status is dependent on the silt laden river water. If the project would not be implemented, most of the project area would remain submerged which would reduce some micro-nutrients availability of soils and would influence to deteriorate soil fertility. On the other hand, the surface water of the rivers contains silts of the river, which would contribute to increase the soil fertility. Full flood control may deprive the soils to receive the fine silts from the rivers.It is likely that river water flooding would sustain the soil fertility from further degradation. Similarly, the soils which are continuously irrigated with ground water may develop toxicity.
5.2.7Agriculture -
The agricultural land use will be degraded in absence of embankments, hydraulic structures, salinity intrusion and siltation of drainage channels. Under the without project condition, the farmers will be discourage to cultivate HYV Boro using surface water irrigation just after harvesting T Aman. If the interventions would not be implemented, the soil salinity would increase beyond critical limit (ECe> 4.0 dSm-1) and the availability of surface water in the river would decrease due to siltation.
5.2.8Livestock -
If the project is not implemented, the land type will be deteriorated and crop production will decrease. People of the coastal area will be desperate for raising the livestock and poultry for their existence. However, due to salinity intrusion and frequent submergence of land grazing areas are reducing. The interventions will help to protect the area from submergence by tidal saline water as well as flood from river water. The intervention may increase fodder for livestock/poultry. This will create very favorable environment for the expansion of livestock rearing in the area.
5.2.9Fisheries -
The water bodies e.g. internal rivers, khals, floodplain and borrow pit canal are present in the project area. Due to continuous siltation, water availability from internal river and khals would reduce especially in dry season. This habitat would become less suitable for fish habitation, production, diversity and migration in future without the project. CEIP will ensure proper operation of the existing sluice gate during fish breeding period which will facilitate fish migration and production.
5.2.10Flora and Fauna -
The aquatic and other habitats will be unchanged without any interventions. But increased water logging may reduce terrestrial habitats with negative impacts on terrestrial flora and fauna. Dying of terrestrial plants at the homestead and roadside is also caused by water logging. Practice of traditional shrimp farming by entering and storing saline water might change flora and fauna composition. The EIA will assess and evaluate the impacts on shrimp farming due to reduced water logging.
5.2.11Socio-economic Condition -
Currently the degree of seasonal as well as permanent out-migration is moderate. The rate is gradually increasing day by day as a consequence of low agriculture practice due to water congestion, salinity intrusion, cyclone, and drought, scarcity of drinking water and eventually low living standard. CEIP project is expected to increase agricultural production, employment opportunity and better communication.
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