Salinity Intrusion due to Fresh Water Scarcity in the Ganges Catchment : A Challenge for Urban Driking Water and Mangrove Wetland Ecosystem in the Sundarbans Region, Bangladesh (original) (raw)
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Mangrove wetland ecosystems in Ganges-Brahmaputra delta in Bangladesh
Frontiers of Earth Science in China, 2008
The Sundarbans is one of the productive mangrove wetland ecosystems in the Ganges-Brahmaputra delta in Bangladesh. The delta is undergoing rapid ecological changes due to human activity. In the present study, surface water salinity data from 13 rivers of the Sundarbans were collected in order to investigate the saline water intrusion in the mangrove wetlands. Results demonstrate that saline water has penetrated the upstream area as river water salinity has increased significantly in 1976 compared to the year 1968. The soil and river water salinity data also shows that it has crossed the water salinity threshold line in most parts of the Sundarbans wetlands. These observations are due to the construction of Farakka Barrage in 1975, which reduced the water discharge of the Ganges River from 3700 m 3 /s in 1962 to 364 m 3 /s in 2006. The shortage of freshwater discharge to the deltaic area is trailing active ecosystems function, especially in the dry season in the south western region in Bangladesh. The objective of this study is to understand and analyze the present degraded mangrove wetland ecosystems and their negative impacts. The findings of this study would contribute to the formulation of the mangrove wetland ecosystems management plan in the Ganges delta of Bangladesh.
Water Salinity Investigation in the Sundarbans Rivers in Bangladesh
Bangladesh, through its complex network of river systems, drains an area of about 1.76 million km 2 of the catchments of the Ganges, the Brahmaputra and the Meghna, of which only 7.5% lies in Bangladesh. The Sundarbans is situated in the Ganges catchment area, which is known as the single largest mangrove forest and unique ecosystem in the world. It has an area 6017 km 2 and a natural shield that protects the coastal area from storm surges and cyclones. It also plays a potential role in the regional economy and ecosystems. Since the diversion of Ganges water at Farakka Barrage in India from early 1975, as a result the water and soil salinity has penetrated. Consequently, both siltation and increased salinity have degraded water quality in the Sundarbans rivers, and threats for mangrove ecosystems. At present, ground water use in the study area is less because of high salinity intrusion. For salinity investigation, time series data for four years (13 rivers) were used for water salinity modelling. The objectives of this paper are to investigate the water salinity approximation in the Sundarbans rivers, which will be considered as a tool for decision making. It will make a contribution to develop an interdisciplinary management plan and to ensure that fresh water is supplied to the Sundarbans by the Ganges for the protection of mangrove ecosystems.
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.
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.
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
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.
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.
RISING WATER SALINITY: A THREAT TO MANGROVES OF INDIAN SUNDARBANS
Mangroves constitute an important ecosystem because of their global extent and high productivity. These plants thrive in the intertidal zones of the tropics and subtropics that are characterized by regular tidal inun-dation and fluctuating salinity. Mangrove species are well adapted, both morphologically and physiologically, to survive under saline conditions, but in hypersaline environment their growth is reduced. The present chapter is a critical analysis on the impact of salinity on the growth of a common mangrove species (Hertiera fomes). The analysis has been carried out in the framework of Indian Sundarbans, which has contrasting salinity profiles in different segments owing to barrage discharge and siltation phenomena. Analysis of the decadal profile of salinity indicates a gradual lowering in the western Indian Sundarbans due to Farrakka barrage discharge and runoff from catchments. The central sector, Water Insecurity: A Social Dilemma Community, Environment and Disaster Risk Management, Volume 13, 167À183
CHAPTER 8 RISING WATER SALINITY: A THREAT TO MANGROVES OF INDIAN SUNDARBANS
Mangroves constitute an important ecosystem because of their global extent and high productivity. These plants thrive in the intertidal zones of the tropics and subtropics that are characterized by regular tidal inundation and fluctuating salinity. Mangrove species are well adapted, both morphologically and physiologically, to survive under saline conditions, but in hypersaline environment their growth is reduced. The present chapter is a critical analysis on the impact of salinity on the growth of a common mangrove species (Hertiera fomes). The analysis has been carried out in the framework of Indian Sundarbans, which has contrasting salinity profiles in different segments owing to barrage discharge and siltation phenomena. Analysis of the decadal profile of salinity indicates a gradual lowering in the western Indian Sundarbans due to Farrakka barrage discharge and runoff from catchments. The central sector,