Since water is a crucial resource, some 35 government agencies are involved in water sector. Bangladesh Water Development Board (BWDB) under the Ministry of Water Resources is by far the most significant organization, handling major portion of all expenditure in water sector. The organization is responsible for planning, construction (including rehabilitation), O&M of infrastructures in FCDI systems like embankments, regulators, barrages etc and overall management of FCDI projects.
- Completed Projects 684 nos
- Length of Embankment 9943 km
- Length of Irrigation Canal 5111 km
- Length of Draiange Canal 3783 km
- Pump House 19 nos
- Barrage 4 nos
- Hydraulic Structures 13949 nos
The Ganges-Kobadak Project is located in South-west Region of Bangladesh. The project is implemented (Phase-I & Phase-II) for FCDI for a gross area of 197000 ha of which irrigation command area is 142000 ha. At present about 100000 ha has been brought under irrigation. After implementation of the project, additional 3.0 lakh MT food grain production was possible by providing FCDI facilities through construction of FCDI infrastructures. It is estimated that market price of this additional crop production is about Tk 3500 million (US$ 50 Million approx). Major infrastructures in this project are given below;
- Pump House 2.0 nos
- Flood Control Embankment 39.0 km
- Irrigation Canal 1655.0 km
- Drainage Canal 971.0 km
- Hydraulic Structure 2184 nos
Command Area Development for Teesta Barrage Project (Phase-I)
The Phase-I of Teesta Barrage Project (TBP) was completed in June 1998 covering a gross benefited area of 1,54,250 ha and a net irrigable area of 111,406 ha. Main objective of the project was to increase productivity of the land by achieving full potential benefit of irrigation in the project area. It provides supplementary irrigation for transplanted Aman. In addition, irrigation of Rabi and Aus crops may also be possible in limited scale depending on availability of surface water resources. After implementation of the project, additional food grain production of Tk 4000 million (US$ 57 Million approx) is now possible by providing FCDI facilities through construction of FCDI infrastructures. Major infrastructures in this project are given below;
- Barrage 1.0 no (615 m)
- Closure Dam 1.0 no (2470 m)
- Flood Control Embankment 80.0 km
- Irrigation Canal 650.0 km
- Drainage Canal 250.0 km
- Hydraulic Structure 1160 nos
Meghna-Dhonagoda Irrigation Project
Meghna-Dhonagoda Irrigation Project (MDIP) is located in the Southeast Region of Bangladesh. The project was implemented with the objective for providing irrigation and flood protection to around 14000 hectares of cultivable land. The project became operational from 1989. Additional 46.0 thousand MT food grain productions are now possible by providing FCDI facilities through construction of FCDI infrastructures. It is estimated that market price of this additional crop production is about Tk 370 million (US$ 5.28 Million approx). Major infrastructures in this project are given below;
- Pump Station 2.0 nos
- Flood Control Embankment 60.0 km
- Irrigation Canal 218.0 km
- Drainage Canal 126.0 km
- Hydraulic Structure 666 nos
Chandpur Irrigation Project
The Chandpur Irrigation Project (CIP) is one of the most successful irrigation and drainage projects of BWDB. The project had been operational since 1979; about 57000 ha under flood control, 28500 ha under irrigation was brought under this project, additional 72.0 thousand MT food grain production is possible by providing FCDI facilities through construction of FCDI infrastructures. It is estimated that market price of this additional crop production is about Tk 600 million (US$ 8.60 Million approx). Major infrastructures in this project are given below;
- Pump House 2.0 nos
- Flood Control Embankment 100.0 km
- Low Lift Pump (LLP) 1600 nos
Muhuri Irrigation Project
The Muhuri river basin is located at middle reach of the South Eastern region of Bangladesh. A closure and a regulator were built near the outfall of the Feni river in 1985 to facilitate improved water management in the Muhuri river basin. Under pre-project condition, total production of crops was 114,799 M.T. In comparison to pre-project condition production, from 1985 till 2001, yearly incremental production of paddy and other crops on average stood at 81,450 M.T., the cost of which is Tk. 505.1 Million (US$ 7.2 Million approx). In pre-project condition, the project area had food deficit but at present it has been turned into food surplus area. The cropping intensity has been raised to 209% from 192% in the past.
- Closure 1 nos
- Regulator 1 nos (40 nos gate)
- Canal 598.0 km
- Bridge/Culvert 74 nos
- Drainage Sluice 8 nos
Approximately 6 million ha have been equipped with some of FCD infrastructures in Bangladesh. Initially emphasis was placed on FCD, but later the focus shifted to FCDI. Achievements due to development of these infrastructures are given below;
In addition, 44.77 lakh ha area was brought under FCD facilities through construction of FCD infrastructures; this created opportunity to increase food grain production to 198 lakh MT. This benefit occurred mostly in the Northeastern region by protecting Boro crops from early flash floods. In total, additional 90 lakh MT food grain production was possible, the cost of which stood at Tk 91800 million (US$ 1311.4 Million approx) (Table-1).
Environmental Improvement : A few of the significant positive environmental impacts are mentioned below;
- Environmental hazards, like loss of land and property have been reduced;
- Flood free environment has made the faster internal infrastructural development;
- Flood free environment has increased afforestation.
- Communications have been improved;
- Health conditions and sanitation have been improved
- Salinity intrusion has been prevented in the coastal area
In late 1980s and 1990s, a more balanced view began to emerge concerning impacts and benefits of FCD projects. Within embanked areas, results were generally positive, especially for agricultural production and increased security from flooding. Where drainage provisions were adequate and access to additional water could be secured in dry seasons, more intensive cropping was achieved; housing conditions improved and services were developed. However, negative impacts inside polders also emerged, for example, as drainage congestion within the embanked areas, an increase in flood depths outside embanked areas occurred due to confinement of the river and flood plain system. As a consequence decline in water bodies, interruption of fish migration patterns, and the general lack of adequate maintenance resulted; hence repairs were frequently needed. Recent impact evaluations on performance of infrastructures for FC and irrigation show that infrastructures for small schemes perform better than large schemes. It has been also observed that coastal areas provides higher returns where there are fewer opportunities for groundwater irrigation and negative effect of saltwater flooding is higher than in inland systems. It has been observed that economic return on about half of the infrastructures for FC and irrigation schemes surveyed were satisfactory (BWDB 1998).
For management of water resources infrastructures, financing maintenance is possibly the biggest bottleneck. Only a third as much as needed is spent on maintenance, which is a constant problem. In addition, lack of stakeholder’s participation is another issue. BWDB mainly performs planning, execution and management of FCDI projects, considering top-down approach. However, GoB’s Guidelines for Participatory Water Management foresee extensive involvement of stakeholders in project planning and implementations as well as management of infrastructures. Initially involvements of stakeholder’s participation in managing infrastructures for irrigation projects have begun but this involvement is also required for FCD schemes as well.
Flood, flood mitigation and management : Floodplains of major rivers and their tributaries and distributaries cover about 80% of Bangladesh. As a result of very flat topography, 20% of the land is inundated due to spilling from rivers during the monsoon period (June-September). Rainfall of high intensity and long duration causes drainage congestion within the country due to inadequate conveyance capacity of rivers and un-favourable tail water situation. The situation becomes severe when peak flow in the rivers synchronizes with high rainfall. The nation experiences around 37% inundation due to floods every 10 years. In 1988 and 1998 more than 60% land on an average was inundated.
FCD projects were mainly conceived to increase agricultural production by protecting agricultural lands from inundation. Usually, in a functional FCD project the F2 or F3 lands are converted to shallower flood phase, thereby, increasing available land for T Aman. In some areas, FCD projects were implemented to protect Boro crops for inundation. FCD projects have mixed results; in some areas these projects helps in raising crop yields the protected areas, the overall benefits; however, this has not been encouraging due to failure in managing external adverse impacts.
The GoB’s policy for food self-sufficiency and security is centered on increased agricultural productivity. However, improved performance of FCD projects would be needed for this. NWPo rightly puts greater emphasis on irrigation development and review of existing FCD projects. Water management inside FCD projects with stakeholder participation or withdrawal from non-performing or poorly performing FCD projects is a major task to be undertaken.
Human interventions in floodplains and associated impacts :
Human intervention in flood plains and water bodies has introduced significant environmental, social and economic impacts. Conventional engineering practices of analysis and design has to use simplified approaches without considering interactive responses from system interventions, which is inevitable in complex river and flood plain system. A unique example of such hazard was KJDRP (Khulna, Jessore Drainage Rehabilitation Project), in the southwest region. Numerous tidal rivers together served as a drainage network for the project area until the mid-sixties. After the construction of Polders and sluices under Coastal Embankment Project, natural tidal circulation was put under control. Tidal prism became greatly reduced; primary consequence was siltation in the drainage network. By early eighties, severe drainage congestion occurred in large waterlogged area. Its adverse consequences seriously affected agriculture, infrastructure, homestead plantations, health and livelihood.
Freshwater withdrawal and salinity intrusion in the Coastal areas : Salinity in the coastal areas, particularly in South West region is a major concern. Salinity intrusion in south west has increased due to low fresh water flow in Gorai during dry season. The main reason is withdrawal of water at the upstream, resulting in degradation of the Gorai Offtake. This has resulted in major adverse impacts on the environment and socio-economic condition. The Ganges Water Sharing Treaty (GWT) with India signed in 1996 provides guarantee to a certain quantum of flows during dry season to Bangladesh. The main challenges in the future would be to best utilize additional flows to restore the Gorai and other rivers; arrest environmental degradation by salinity control; extend irrigation facilities and control of sedimentation. Diversion, distribution and management of additional flow requires for major interventions like Barrage on the Ganges, water control structures and distribution canal in Ganges Dependent Areas (GDA). A detailed study on the feasibility of various intervention options should be immediately undertaken.
|Siltation Problem in Monu River|
Erosion of river banks : Seasonal variations of river flow causes variations in sediment transport, resulting in erosion of river banks. The possible after effects are migration of bank lines, resulting loss of valuable lands. Previous studies estimated that by year 2025 around 3,575 km2 areas in erodable river valleys of Brahmaputra, Ganges, Padma, Lower Meghna and estuary will be lost due to erosion. On the other hand, 3,665 km2 lands will be gained due to accretion in the same period. From these figures it may seem that loss is not very significant, however, this has major social, economic and environmental implications. Structural measures like river bank protection, canalization etc. for mitigation of erosion in extremely dynamic river valleys of Jamuna, Padma, Ganges or Lower Meghna would require huge investment. Planning for such mitigation measure requires prediction of river erosion and most suitable measure for mitigation based on resulting impact at upstream and downstream of mitigation work. Remote sensing data can be used for study of pattern changes in river plan form and bank lines. Mathematical models could be useful to predict river erosion, and study of different mitigation options and their impacts. Prediction of erosion for early warning can also save life and property.
One of the major mitigation measures includes land use policies, which should guide development activities in disaster prone areas. The land use policy should be based on analysis of risk due to hazard. Deterministic models can be used to simulate any events and GIS could be very a handy tool for risk mapping based on risk analysis. Probabilistic models could be used to take into account of the whole range of likely events by assigning probabilities to each range of events and estimating damage that would be expected to occur as a result.
Water stress : Agricultural drought is a common phenomenon in many areas of Bangladesh in post monsoon and dry season. In important cities, scarcity of water for drinking and sanitation is a major problem. Main causes of draught are limited rainfall, high temperature associated with low humidity and withdrawal of water at upstream. Over withdrawal of groundwater is causing lowering of groundwater in many areas, resulting many Shallow Tubewells (STW) being inoperable. Moreover, low flow in rivers in dry period and lowering of groundwater table is causing environmental problems like salinity intrusion in surface and groundwater, increase in the concentration of pollution in surface water, sedimentation etc.
Urban water supply and sanitation : Pollution from human and industrial sources is the main water quality problem in river systems near urban areas. Buriganga in Dhaka and Karnafuli in Chittagong are the worst affected. Other rivers are also shows gradual decline in water quality. This has posed to be a major problem in extracting required water from these rivers for drinking water and domestic activities. It has been estimated that urban population will increase by 2.7 times by 2025. The gross daily water demand in the major Metropolitan Cities (Dhaka, Chittagong, Khulna and Rajshahi) will rise from present 2460 Ml/d to 7970 Ml/d assuming a system loss of 20%. There is already a major short fall of required supply of safe water. Due to over abstraction and loss of recharge areas, groundwater table in Dhaka city has declined at an alarming rate over last couple of decades. A 1997 study by SWMC shows that maximum drawdown due to groundwater abstraction was 25m. However, the drawdown could be reduced to 15m by conjunctive use of surface and groundwater. Based on model study, SWMC recommended use of surface water during wet season from rivers surrounding Dhaka city and groundwater during dry period. It may be mentioned that cost of treatment of surface water will be lower in wet season because of lower pollution level. Recharge during wet season will raise groundwater table, which will reduce cost of groundwater abstraction during dry season. Alternative sources like Jamuna, which is only 80km away with reliable flow needs to be investigated. Conjunctive use in other major cities and urban areas should also be studied. Other options relates to more stringent regulations implemented on the ground relating to protection of the quality of water and reduction of wastage and unaccounted-for-water. Community participation in the process is vital. Demand management by imposing stepped tariffs could be useful to discourage wastage of water. Private sector management of water supply system could be more efficient in management of demand and quality services.
Dhaka has the largest piped sewerage system in Bangladesh; however, the existing system serves only 20% of the city. Only 1% of this reaches DWASA sewage treatment plant at Pagla, the rest leaks into ground or surface water system, which cause widespread pollution. Dhaka city’s 40% households have septic tanks with soak wells. In near future, with increase in population density, quantities will not only exceed soak well capacity, but high land values will discourage setting aside of land for such purposes. Therefore, immediate measures to collect and carry the effluent for treatment and disposal are necessary.