Oxbow Lakes: Unsung Heroes of the Indian Floodplains

Kunal Konar
1 day ago
12 min read

Updated: 14 hours ago

Authors: Dr. Arnab Ghosh, Er. Kunal Konar

Contacts: drarnab.swre@gmail.com; konar.kunal@gmail.com

1 Prologue

I learned about ox-bow lake probably in Class-VI, when I was introduced to the science of Physical Geography by an well-known Bangla School Text Book by Basu & Moulik on Geography. After almost 32 years later, I am publishing an article on this phenomenon of nature (Ox-bow lakes) which occurs in the lower reaches of almost all the great river systems in this planet.

As a Water & Environment Professional, I studied these lakes as Ponds, Bills, Dhars, Tals, Chars etc. in the middle Ganga plains and North-Eastern India (e.g. Loktak Lake). So, I did a small opening Section (Section 2) to contextualize the solutions this blog article offers for all Water & Environment people, policy makers, academicians, government bodies, professional bodies, and civic societies. Other than that, I reviewed the first draft and reformatted it for web-publishing and did the bibliography section and at the very end the Author’s profile.

Rest of the draft, initial conceptualization, illustrations etc. are done by the lead Author, Dr. Arnab Ghosh. I am publishing it for the global readership in the hope that they will find it a good technical read and chalk out some systemic action points around the proposed solutions indicated here by the lead Author.

~~ Kunal Konar, Editor, Co-author, and the Publisher.

2 Case Study of the Beledanga Ox-bow Lake

Let us start by looking at a relevant and recent research article on these special classes of floodplain lakes, titled, “Ecosystem services assessment of Beledanga oxbow lake in the Gangetic plains: pathways to sustainable conservation” (Ekka, et al., 2024). In this article, the authors and their whole team (consists of scientists and staffs from two internationally recognized institutes (the Central Inland Fisheries Research Institute (ICAR), Kolkata, India and the Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, Netherlands) concentrated their cumulative efforts to quantify the ecosystem services provided by a medium sized ox-bow lake, namely, Beledanga Lake (these are locally known as ‘Baor’ and Beledanga Lake is also locally known as Natidanga Baor) in the Ichamati River System. This gives us the opportunity to map and quantify how many such lakes are there in a river system typical of the deltaic region of one of the largest and diverse River Basin – the Ganga-Meghna-Brahmaputra Basin. This is done in the next-subsection before returning to more subtle and important topic i.e. Ecosystem Services provided a small perennial wetland to the people and nature.

2.1 Ox-bow Lakes: How frequent are these Wetlands?

Towards this end a quick desktop study is planned and executed via Open-Source Desktop GIS Tool (QGIS 3.4 LTR) and freely available data from Global Map Service Providers (Open Street Map and Google Roads). Figure 1 summarizes the result.

The river Ichamati originates from a river named Mathabhanga. Mathabhanga River is a branch river of the River Padma (known as Ganga in India). According to the data updated in Open Street Map, the length of Ichamati River is 269 km. Visual inspection via Desktop GIS suggests that there are 19 ox-bow lakes at present and all occurring within the middle reaches of the river. All these ox-bow lakes and their approximate surface area are listed in the infographic of Figure 1. The total surface area of these lakes is ~ 14.172 sq. km. These 19 lakes have been formed over a range of the river measuring about 63 km (aerial distance). Within India (West Bengal) it flows through Krishnanagar, Bangaon, Basirhat sub-divisions. This river forms the present-day international boundary between India and Bangladesh along two stretches of Nadia and North 24 Parganas.

Figure-1: Map showing all of the 19 Ox-bow Lakes within Ichamati River System

Ichamati’s rich floodplains directly sustains the livelihoods of indigenous riverine communities coupled with thousands of migrant labourers and refugees residing along and across its basin in North 24 Parganas district of West Bengal. Referring from another blog article written by Akshat Mishra in 2022 in the India Water Portal’s website,

Livelihood: Ichamati supports livelihood of about 200,000 people.
Bio-diversity: “Ichamati is one the of major feeder rivers traversing along the Sundarbans Biosphere Reserve which is a hotspot for 1186 numbers of known irreplaceable biomes (Iqbal, 2020) including 334 plants (Uddin, 2025), 322 fish and 428 bird species, to list a few. Ichamati swerves through this estuarial ecosystem which is a stronghold for threatened and endangered avian species like white-rumped vulture, masked finfoot, brown-winged kingfisher in addition to the Royal Bengal Tiger, Irrawaddy dolphin, Indian python, estuarine crocodile and river Terrapin.”

And there lies the importance of this river – it is the lifeline for about 200,000 people or more and even at its current status of siltation and high pollution level, the river is capable of supporting wide variety of bio-diversity. This is probably one of the reason that the Inland Waterways Authority of India has already marked a 63.4 km reach of this river as the National Waterway No. 44 and commissioned a DPR level study by the M/S Egis India Consulting Engineers in 2019.

Out of 19 lakes, 6 are in Bangladesh and rest of the 13 are in India; 7 lakes are in the right bank of Ichamati and rest of the 12 lakes are in the left bank. So, in summary this special class of floodplain lakes which happens to have an important hydraulic/geomorphologic feature – the Tie Channels (i.e. the water course that links these lakes to the main rivers during the monsoon floods) for engineering intervention may occur frequently for some rural areas of interest and provides for ideal natural systems for planned and policy level intervention for the benefit of this planet’s bio-diversity and material value to the surrounding populace. This statement shall be made clear in the next sub-section.

2.2 Ecosystem Services from Beledanga Ox-bow Lakes

Now let’s go a bit finer on spatial scale and focus on a single ox-bow lake within Ichamati River System. Let us extract and present the key results from the study performed by a highly acclaimed group of applied scientists from the CIFRI and Delf Technical University, Netherlands and reported in 2024 (Ekka, et al., 2024).

In this study the authors quantified the ecosystem services provided by the Beledanga Ox-bow Lake using Millenium Ecosystem Assessment Framework of the United Nations. They have employed following experimental and analytical tools in their study:

Field surveys;
Stakeholders' consultations; and
Secondary data analysis like literature survey etc.

Following key features about the Beledanga Lake are reported in the study:

Average rainfall: 1538 mm
Mean annual temperature: 26.2°C
Relative humidity ~ 59%
Recent droughts: 2017 and 2020
Reduction of lake’s Water Surface Area: From ~ 65.15 hectare (0.6515 km2) in 1980 to 46.00 hectare (0.46 km2) in 2020. They attributed this area reduction to “ encroachment, water stress, macrophyte infestation, and sedimentation, all exacerbated by the impacts of climate change”.

Table 1 Summarizes the Ecosystem Services provided by the Beledanga Oxbow Lake.

3 Nature’s Dynamic Meandering Cut-off

Oxbow lakes that assume a characteristic U shape in response to a meandering fluvial channel abandoning one of its branches are stable and relatively stable water environments (Knighton, 1998). The Gangetic plains of India have some of the best examples, like Beledanga and Bhomra, although small in surface area, that have a disproportionate ecological impact, documenting the river's geomorphological record (Sinha & Ghosh, 2012). Their constant sculpting and silting occur naturally, representing an active but regular evolutionary process. Their constant sculpting and silting occur naturally, representing an active but regular evolutionary process.

Figure-2: Oxbow Lake Formation and Benthic Ecosystem Structure (Diagram Courtesy: Lead Author)

4 Blue Carbon Stock

These water bodies cannot be taken to mean stagnant houses but dynamic biogeochemical pumps. During monsoon floods, they hold suspended sediments and nutrient loads, and thus act as filters that improve water quality downstream (Mitsch & Gosselink, 2015). Most importantly, the sedimentary layers of hypoxia serve as productive reservoirs of blue carbon, sequestering carbon at levels three to four times higher than those in conventional agricultural soils, thereby damping climate perturbations resulting from human activities (Nashik & Fennessey, 2016). This sequestration depends on the presence of a flourishing microbial community within the depositional matrix; bacterial and fungal communities develop successively as the lake ages, directing detrital organic matter into non-biodegradable carbon stores (Bridgham, et al., 2006). As a result, the oxbow lakes take a disproportionate share of the world's carbon tally in the world carbon account, even though they occupy only a small area of land.

5 Biodiversity Hotspot

These lakes serve as critical biodiversity sources and suitable breeding sites; e.g. one such study reported that these lakes may host over 90 ichthyic species (Sarkar & Borah, 2017). These form serene, nutrient-rich retreats for ova and juvenile life. The changed nature of ichthyofaunal composition shows temporal variations, with the greatest change occurring during the seasonal peak of species richness in the wake of monsoonal conditions, which creates hydrological connections between the lacustrine system and the main river through the so-called tie channels (Dutta, et al., 2020). Ecosystem services form the basis of the communal livelihoods of proximate human settlements. Business fisheries provide essential sources of protein and income streams, whilst lacustrine discharges supply irrigation water invaluable to premium agrarian products during dry periods, thus supporting a multi-sectoral green economy (Junk, et al., 2013). This combined bioeconomic matrix supports thousands of livelihoods through activities such as fishing, crop farming, and duck husbandry.

Figure-3: Ecosystem Services and Livelihoods from Oxbow Lakes (Courtesy: Lead Author)

6 Constraints

However, oxbow lakes are subject to significant anthropocentric stress. Over-fishing, pollution inputs, and agricultural activity have been found to cause a 41% loss in fish diversity (Sarkar, et al., 2019). The most critical danger is when the sedimentation is accelerated, enhanced by the sealing of tie-channels that result from upstream land-use alterations and the development of floodplain embankments, isolating these lakes and interfering with their natural ecological processes (Ghosh, et al., 2025).

7 Solutions

The leading solution would be to replenish the hydrological connectivity of the floodplain system with nature (Opperman, et al., 2010). For example,

we can improve water quality and restore fish assemblages by breaking anthropogenic boundaries and dredging tie-channels in a matter of years (Tockner, et al., 2010).
Re-instating the natural dynamics of a flood pulse should be at the forefront of management issues, rather than the artificial operational sequence of gates, because seasonal flow provides a vital source of nutrients and food for fish in generating cycles (Junk & Wantzen, 2004).
Sustainable fisheries management, which includes limits on catches, size limits, and bans on destructive gear, is a necessity (Welcomme, et al., 2010).
At the same time, protecting oxbow lakes provides a significant climate finance opportunity; they have higher rates of carbon sequestration, which could generate substantial revenue potential from carbon markets (Moomaw, et al., 2018).

Thus, an investment in conservation will yield additional value in the form of flood reduction and groundwater restoration.

7.1 Innovative Ideas

Innovation provides more avenues to support resilience.

By incorporating,
- renewable energy systems, e.g., photovoltaic arrays located along the margins of the floodplain,
- downstream value-added processing, such as fish drying, can be turned on, and market access expanded to increase profitability (UNDP, 2021).
- combined solar-wind systems will guarantee a stable energy supply to local populations, transforming traditional ways of life into more sustainable, climate-resilient businesses (IPCC, 2022).

To sum up, oxbow lakes are complex ecological resources, characterized as dynamic carbon sinks, biodiversity reserves, and socioeconomic icons. Their redevelopment creates an interesting model for environmental health, climate change reduction, and community strength, in harmony with nature's natural cycles.

8 Research related Contributions

The insights presented in this blog article are derived from my own experience in several peer-reviewed studies conducted in the Bhagirathi-Hooghly basin, which further elucidate the ecological, hydrological, and socio-economic dimensions of floodplain wetlands.

Water Productivity of Wetlands (Roy, et al., 2021): This study applied the AquaCrop model to assess water productivity in six wetlands of the Bhagirathi-Hooghly sub-catchment. Findings reveal that aquatic resource productivity (fish and aquatic plants) exceeds rice productivity by 7%, driving a livelihood shift from agriculture to aquaculture. Land use change analysis (2014–2019) showed a decline in water area (up to 42%) and an increase in dryland and settlements, highlighting growing human pressure on these ecosystems.
Seasonal Dependency on Wetlands (Roy, et al., 2021): Using bathymetry, water quality indices, and trend analysis (Seasonal Kendall test, ARMA modelling), this research documented sedimentation and pollution in wetlands like Bhaluka, Bhomra, and Chupichar. Despite wetland decay, rice and fish production increased, reflecting intensified human dependency. The study underscores the need for dredging, pollution control, and sustainable management to maintain wetland functions amid climatic variability.
Meandering River Dynamics (Ghosh, et al., 2020): Focusing on riverbank erosion and channel migration in the Bhagirathi-Hooghly stretch, this study employed a Migration Coefficient (MC) approach and GIS-based modelling to predict future centreline shifts. Results indicate eastward migration and increasing sinuosity, which raise erosion risks for riverside communities and infrastructure. The research aids in forecasting vulnerable zones and supports planning for bank stabilization and flood management.

Collectively, these studies reinforce the critical role of oxbow lakes and wetlands as dynamic socio-ecological systems, warranting integrated management to balance productivity, biodiversity, and resilience in the Gangetic floodplains.

9 References

Bridgham, S. D. et al., 2006. The carbon Balance of North American Wetlands. Wetlands, 26(4), pp. 889-916.
Dutta, S., Saha, A. & Majumdar, M., 2020. Hydrological connectivity and fish assemblage structure in floodplain lakes of the Brahmaputra basin, India. Environmental Biology of Fishes, 103(2), pp. 145-160.
Ekka, A. et al., 2024. Ecosystem services assessment of Beledanga oxbow lake in the Gangetic plains: pathways to sustainable conservation. Frontiers in Freshwater Science, Volume 2.
Egis India Consulting Engineers, 2019. Final Detailed Project Report (DPR) of National Waterway No. 44, Volume-1: Main Report.
Ghosh, A., Roy, M. & Roy, P., 2020. Estimation and prediction of the oscillation pattern of meandering geometry in a sub catchment basin of Bhagirathi Hooghly River, West Bengal, India. SN Applied Sciences, 2(1497).
Ghosh, R. et al., 2025. Impact of channel bottlenecking and anthropogeomorphic interventions on flood and wetland conditions in the lower gangetic floodplain. Environmental Earth Sciences, 84(604).
IPCC, 2022. Climate Change 2022: Impacts, Adaptation and Vulnerability, s.l.: Inter Governmental Panel on Climate Change.
Iqbal, M. H., 2020. Valuing ecosystem services of Sundarban Mangrove forest: Approach of choice experiment. Global Ecology and Conservation, 24(2020).
Junk, W. J. et al., 2013. Current state of knowledge regarding the world’s wetlands and their future under global climate change: A synthesis. Aquatic Sciences, 75(1), pp. 151-167.
Junk, W. J. & Wantzen, K. M., 2004. The flood pulse concept: New aspects, approaches, and applications An update. Rome, FAO, pp. 117-140.
Knighton, D., 1998. Fluvial forms and processes: A new perspective. s.l.:Arnold.
Mitsch, W. J. & Gosselink, J. G., 2015. Wetlands. 5th ed. s.l.:John Wiley & Sons.
Moomaw, W. R. et al., 2018. Wetlands in a changing climate: Science, policy and management. Wetlands, 38(2), pp. 183-205.
Nashik, A. & Fennessey, M., 2016. Carbon storage in US wetlands. Nature Communications, 7(1), p. 13835.
Opperman, J. J. et al., 2010. Ecologically functional floodplains: Connectivity, flow regime, and scale. Journal of the American Water Resources Association, 46(2), pp. 211-226.
Roy, M. B., Ghosh, A., Kumar, A. & Roy, P., 2021. Assessing the nature of seasonal meteorological change in people’s dependency on wetland: a case study of Bhagirathi–Hooghly floodplain system. Development and Sustainability, 23(12), pp. 17881-17903.
Roy, M. B., Ghosh, A., Kumar, A. & Roy, P., 2021. Study of water productivity model on wetlands: a case study of Bhagirathi-Hooghly sub-catchment basin, Southern West Bengal, India. Environmental Monitoring & Assessment, 193(10).
Sarkar, U. K. & Borah, B. C., 2017. Floodplain wetland fisheries of India: With special reference to impact of climate change. Wetlands Ecology and Management, 25(1), pp. 1-15.
Sarkar, U. K. et al., 2019. Status, potential, prospects, and issues of floodplain wetland fisheries in India: Synthesis and review for sustainable management. Reviews in Fisheries Science & Aquaculture, 27(2), pp. 155-174.
Sinha, R. & Ghosh, S., 2012. Understanding dynamics of large rivers aided by satellite remote sensing: A case study from Lower Ganga plains, India. Geocarto International, 27(3), pp. 270-219.
Tockner, K., Pusch, M., Borchardt, D. & Lorang, M. S., 2010. Multiple stressors in coupled river–floodplain ecosystems. Freshwater Biology, 27(3), pp. 207-219.
Uddin, S., 2025. Life in the Sundarbans Mangrove Forest. [Online] Available at: https://uddin.digital.conncoll.edu/sundarbans/global/loss-of-biodiversity/ [Accessed 27 Januray 2026].
UNDP, 2021. Renewable energy for sustainable livelihoods, s.l.: United Nations Development Programme.
Welcomme, R. L. et al., 2010. Inland capture fisheries. Philosophical Transactions of the Royal Society B: Biological Sciences, 365(1554), pp. 2881-2896.

10 About the Lead Author

Dr. Arnab Ghosh was graduated in Geography from Calcutta University in 2008 and then did his Master of Arts in Geography and Disaster Management in 2010 from Ravindra Bharati University. He stayed in academia and went on to the School of Water Resources Engineering Jadavpur University and completed his doctoral degree (PhD) from there in 2022. His research topic was “Study on River Dynamics of Floodplain System with Special Reference to Avulsion of Bhagirathi.”

Till date, Dr. Ghosh has authored or co-authored 15 journal articles and 9 book chapters. He is also an active professional in the consulting domain with 9 projects where he has worked as either project scientist or project assistant.

Dr. Ghosh gained deep understanding and skills in solving water related problems using GIS & RS and hydrologic and hydrodynamic modelling tools.

He has also worked in the field during many of his academic and consultancy projects and conversant with tools and technologies like Acoustic Doppler Current Profiler (ADCP), Echosounder, Total Station, DGPS, Dumpy Level, Current Meter on bathymetric measurement of river and analysis of retrieved data through WIN RIVER II software, including lab-based module and field survey techniques. Also used Acoustic Doppler Velocimeter (ADV) in flume-based studies on bank erosion protection, flood protection, and bridge scouring. Likewise, he has obtained acquired deep skills in numerical modelling tools commonly used in many classes of water related studies like SWAT, MIKE NAM, MIKE 11, HEC-RAS 1D and 2D, HEC-HMS and BSTEM, FLO 2D, FLO 3D, Delft 3D, Water GEMS and Flood. On the GIS-RS domain he is conversant with ArcGIS, QGIS, Google Earth Engine etc. Finally, he is also conversant with Data Science and generic computational tools like R, Python, MATLAB and Origin.

Classes of engineering problems undertaken by him is widely varied; some of the key uses cases are river bank protection, climate change studies, sedimentation studies, dam break studies, bridge scouring, land use analysis, climatic hazard, 1D and 2D inundation modelling, 2D urban flood modelling, EIA and Rapid-EIA, Wetland Valuation etc. He may be reached at: drarnab.swre@gmail.com; and more about him may be found at: