Mangrove wetland ecosystems in Ganges-Brahmaputra delta in Bangladesh (original) (raw)
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The Sundarbans is situated in the Ganges transboundary catchment which is known as the single largest mangrove ecosystems in the world and covers 10,000 km² between Bangladesh and India. Since the diversion of Ganges water at Farakka Barrage in India from early 1975, salinity level has increased drastically in the south western part of Bangladesh. Due to reduction of fresh water flow urban drinking water supply, industrial production, agriculture, fisheries, navigation, hydromorphology and mangrove wetlands ecosystems have been affected. Urban area both surface and groundwater have become unfit for human consumption. In the consequences about 0.170 million hectares (20.4%) of new land, and almost 27 small towns have been affected by various degrees of salinity during the last three decades. The saline front defined by 6 dS/m iso-haline has penetrated up to 173 km north from the coast. The salinity has exceeded the recommended level 1 dS/m for potable water. It is a new threat to supply quality drinking water to the small towns in the south western region in Bangladesh. The dominant mangrove Heritiera fomes and Ceriops decendra species are affected by top dying disease which is recognised as key management concern. The Fourier Polynomial water salinity models on Sundarbans rivers are showing the cycling increasing behaviour. The findings of this study a potential contribution for making comprehensive management plan are for urban water supply, and protection of the mangrove wetlands ecosystems in the Sundarbans region.
2011
The Gorai River is the major distributary of the Ganges River in the right bank and important provider of fresh water inflows to southwestern region of Bangladesh. The length of the river is 199 km and the area of the Gorai River catchment is 15160 km². The Gorai used to discharge into the Bay of Bengal through the Mathumati and Baleswar Rivers. The Madhumati was connected to the Nabaganga at Bardia point. This is the drainage path of the Gorai water, which now reaches the Bay mainly via the Passur and Sibsa Rivers. The distribution of the Gorai River flow at Bardia between the Nabaganga and Madhumati Rivers and tidal conditions which influence the sediment concentration are not known. From previous study result shows that the annual average bed materials transport in the Ganges River is about 18X106 metric tons and one third of the Ganges sediment is settling down on the Gorai River basin. The mean peak flow in the Gorai River was 6,200 m³/s in 1962 and the present minimum recorded flow in the dry season is only 10 m³/s in 2008. This is the main reason of the Gorai River bed ridged by sedimentation. It has been observed that the major part of the Gorai River basin is dry, and as a result the sea saline water is penetrating in the upstream of the Gorai River catchment. Salinity intrusion along the Nabaganga-Rupsha-Passur system has largely been influenced by the dry season flow of the Gorai River. The high sediment concentration reaches about 20 km upstream of Bardia and a clean concentration gradient can be observed along the down stream direction of the Gorai and the Nabaganga River. The Gorai is a crucial instrument for maintaining both ecosystems and economy of the region. Since 1980s, the flow in the Gorai River has been blocked by the build-up of sediment in the off-take. After construction of Farakka Barrage on the Ganges River in 1975 in India which is 17 km far from the Bangladesh border, as a result the Ganges water flow has reduced significantly in the down stream. This shortage of fresh water in the Gorai basin is the root cause of salinity intrusion in the catchment and damage of mangrove ecosystems and its services of the Sundarbans region. The study is carried out based on primary and secondary data sources. The objective of this study is to investigate the shortage of fresh water in the Ganges-Gorai basins and their negative impacts on socio-economy and mangrove wetland ecosystems in the Sundarbans in Bangladesh. Keywords: Gorai River, Water shortage, Sedimentation, Salinity intrusion and Mangrove ecosystem and Sundarbans
Through their complex network of river channels, the Ganges, Brahmaputra and Meghna Rivers cover an area of about 1.76 million km 2 , their boundaries extend across different countries such as Bangladesh, Bhutan, China, India, and Nepal. The Sundarbans are found at the coast of the Ganges River and are known as the world's single largest mangrove forest with 3.5 percent of the world's mangroves covering an area of 6017 km 2 . The Sundarbans wetlands act as a natural shield that protects the coastal area from storm surges and cyclones in pre and post monsoon periods. However, due to increased in irrigation of agriculture, industrial activity and the diversion of Ganges water at Farakka Barrage (India) in early 1975, both siltation and salinity have increased in the Sundarbans which is threatening the Sundarbans ecosystems. Consequently the dominant Sundari (Heritiera fomes) and Goran (Ceriops decendra) are affected by top-dying disease which is recognized as a key management concern. The Ganges water sharing is not just a geo-technopolitical problem; it is also a humanitarian problem. So, interaction and educational awareness between concerned states are of great significant. The objective of this paper is to make a contribution towards the development and implementation of management plan for mangrove wetlands resources and to ensure that fresh water is supplied to the Sundarbans by the Ganges. Water salinity simulation and modeling would be a proper tool for decision making and allow planners to protect the Sundarbans ecosystems in future.
Hydrologic monitoring and analysis in the Sundarbans mangrove ecosystem, Bangladesh
Journal of Hydrology, 2007
The unique habitat of the Sundarbans mangrove ecosystem is dependent upon the hydrological regime. Therefore, a comprehensive study to understand the hydrologic behaviour and the changes that have taken place due to anthropogenic activities in and around the area is fundamental to the management of natural resources and environment. In the past, ad hoc and uncoordinated efforts were made due to the inherent inaccessibility and high cost of data collection. The present article documents the results of the hydrologic monitoring, modelling and analysis in the Sundarbans. The study results show that the annual maximum tidal range has increased by about 0.75 m in the eastern and central parts during the last two decades. About 60% area remains in higher salinity condition (>20 ppt) for at least 1.5 months in a year. Organic pollution in the waterways is within the Environmental Quality Standard (EQS) of Bangladesh with the average Dissolved Oxygen (DO) of 5.99 mg/L. Total Ammonia, Nitrate (NO 3-N) and Phosphate (PO 4-P) level are present in sufficient quantity for the aquatic life to survive and are within EQS limit. Lead and Chromium occasionally exceed EQS limit especially along the large barge routes in the western part. The data and information presented in the paper will serve as a baseline for future hydrological and environmental studies.
Threats to the Sundarbans Mangrove Wetland Ecosystems
2009
Through their complex network of river channels, the Ganges, Brahmaputra and Meghna Rivers cover an area of about 1.76 million km 2 , their boundaries extend across different countries such as Bangladesh, Bhutan, China, India, and Nepal. The Sundarbans are found at the coast of the Ganges River and are known as the world's single largest mangrove forest with 3.5 percent of the world's mangroves covering an area of 6017 km 2. The Sundarbans wetlands act as a natural shield that protects the coastal area from storm surges and cyclones in pre and post monsoon periods. However, due to increased in irrigation of agriculture, industrial activity and the diversion of Ganges water at Farakka Barrage (India) in early 1975, both siltation and salinity have increased in the Sundarbans which is threatening the Sundarbans ecosystems. Consequently the dominant Sundari (Heritiera fomes) and Goran (Ceriops decendra) are affected by top-dying disease which is recognized as a key management concern. The Ganges water sharing is not just a geo-technopolitical problem; it is also a humanitarian problem. So, interaction and educational awareness between concerned states are of great significant. The objective of this paper is to make a contribution towards the development and implementation of management plan for mangrove wetlands resources and to ensure that fresh water is supplied to the Sundarbans by the Ganges. Water salinity simulation and modeling would be a proper tool for decision making and allow planners to protect the Sundarbans ecosystems in future.
Bangladesh through its complex network of river systems drains an area of about 1.76 million sq. km ofthe catchment ofthe Ganges, the Brahmaputra and the Meghna of which only 7.5 percent lies in Bangladesh. The Sundarbans is situated in the Ganges catchment area which known as the single largest stretch ofproductive mangrove forest and unique ecosystems in the world. It is reprcsenting 3.5 percent of the world mangrove and consisting of an area 6017 sq. km. It provides direct employment opportunity to 600,000 people and 6 million people indirectly dependent. Since the diveßion of Ganges water at Farakka Barrage in India from early 1975, salinity levels have increased drastically in the coastal region in Bangladesh. The reduction ofGanges flows while the industries are facing serious problems in quality control of products and disastrous effects on agriculture, fisheries, navigation, hydro-morphology, drinking water, wetlands and mangrove ecosystems. The dominant flefi/iera fomes ard Ceriops decandra species are affected by top-dying disease which is recognised as key management concern. The Ganges water shadng is not just a geo-techno-political problem it is also a humanitarian problem. The objectives of this paper is to contribute to formulate a long-term management plan for mangrove wetlands resources through ensure to supply Ganges water into Sundarbans. GIS simulation and salinity model would be the proper tools for decision making and make recommendations for the future of Ganges water sharing conflict and protection of Sundarbans wetlands ecosystems.
Salinity intrusion affecting the ecological integrity of Sundarbans Mangrove Forests, Bangladesh
International Journal of Conservation Science, 2017
The raising of the sea causes salinity intrusion into fresh water zones such as river, lake, floodplain and other lowlands. Salinity intrusion in the Mangrove forest is a continuous process. However, due to the increasing salinity ecological integrity of the Sundarbans have been largely affected. The compositional and functional aspects of flora and fauna have been changing at a great deal. The objective of this study is to delineate the changes of the structure and composition of the Sundarbans Mangrove Forest due to excess salinity intrusion and how salinity affect its biodiversity, wildlife habitat and other ecosystem components. This study reviewed related literature gathered through an extensive survey of various websites and the secondary data obtained from various departments with necessary modifications. The land use maps collected from the Bangladesh Forest Department were interpreted to achieve an elaborate classification of forest type and its gradual change with increasi...
Saline Zone at the Sundarbans Mangrove Forest of Bangladesh
2009
The Sundarbans in Bangladesh part is one of the largest mangrove forests in the tropics comprising about six thousand square kilometers of forest area. It possesses unique character of having ebb and tide at every six hours, hence having salinity intrusion in its rivers and canals from Bay of Bengal. The forest is experiencing heavy saline intrusion in its lower saline zones. Therefore, there is a need to enumerate the saline water intensity in various zones of the forest. Present study tries to find out how much saline intensity exists in different rivers and canals of the Sundarbans. Results depicts that saline intensity was much higher in southwestern part, where it is moderate in northeastern part. Present study reveals the range of PH values between 6.5 and 7.7. PH was found to be lower in Kachikhali and Karamjol points, where Katka, Dublar char and Hiron point shows higher value i.e. near alkaline water. Western zone is higher saline intensive than eastern part. Electrical conductivity found to be between 5.2 and 24 dSm-1 (desi siemens per meter) in different sample collection points. Amount of NaCl (mg/L) was found between 15 and 30 mg/L. Therefore, the Sundarbans river systems and canals have strong saline intensity and the water quality seems to be brackish.