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Haor

A haor is a large, bowl-shaped tectonic in the northeastern region of , functioning as a seasonal that remains submerged under water for approximately six to eight months of the year during the monsoon season, reaching depths of up to 7 meters, before drying out to reveal fertile alluvial soils suitable for in the . Geographically, haors are concentrated in the Sylhet Basin within the , spanning about 1.99 million hectares across seven districts—Sunamganj, Habiganj, Netrakona, , , Maulvibazar, and —and are bounded by the Plateau to the north, the Indo-Burman Range to the east, and the Old Brahmaputra to the west. These depressions receive floodwaters from 23 transboundary rivers, including the and Kushiyara, originating in the hills, along with high annual rainfall ranging from 2,200 mm in the west to over 12,000 mm in upstream areas, leading to rapid inundation and vulnerability to flash floods and sedimentation. Ecologically, haors serve as critical hotspots, hosting over 140 native species, 200 aquatic plant , and 257 bird , including migratory waterfowl, while functioning as natural reservoirs that regulate flows in the Meghna system and support swamp forests of like hijal and koroch trees. Socio-economically, the haor region sustains a population of approximately 20 million people (as of 2022), with livelihoods heavily dependent on boro rice cultivation—which accounts for about 15% of Bangladesh's total rice harvest—and inland fisheries contributing around 20% of the country's fish production. Notable haors include Tanguar Haor, a Ramsar-designated wetland, and Hakaluki Haor, an ecologically critical area, both recognized for their ecological value and role in flood mitigation, though the region faces challenges from climate change, habitat degradation, and agricultural intensification that threaten its wetland integrity.

Haor Characteristics

A haor is defined as a bowl- or saucer-shaped shallow depression that functions as a backswamp within floodplain ecosystems, primarily found in the northeastern region of Bangladesh. The term "haor" derives from the Bengali word "হাওর," a corruption of the Sanskrit "sagor" meaning "sea," reflecting its expansive, sea-like appearance during flooding. Physically, haors are large floodplain depressions that remain inundated for extended periods, with water depths typically ranging from 1 to 3 meters in the dry season, concentrating in central beels and channels, and rising to 3 to 8 meters during the monsoon floods, reaching up to 10 meters in some haors such as Tanguar Haor. These features distinguish haors from related wetlands like baors or beels, which exhibit different hydrological retention patterns. Seasonally, haors transform dramatically: they become waterlogged and lake-like from to under influences, supporting aquatic habitats, before draining to form marshy grasslands from November to May, enabling terrestrial uses. This cycle sustains a dynamic freshwater with high productivity, particularly in fisheries—contributing approximately 20% to Bangladesh's inland through diverse spawning grounds—and agriculture, where dry-season rice cultivation thrives on the fertile soils.

Baor, Beel, and Jheel

Baors are lakes formed by the cutoff meanders of rivers, particularly in the moribund regions where river courses shift, creating isolated, crescent-shaped water bodies that retain water year-round. These features are predominantly located in southwestern , such as in the districts of , , and Faridpur, where they function as permanent freshwater habitats embedded within the floodplains of rivers like the . Unlike the seasonally inundated haors, baors maintain relatively stable water levels due to their enclosed nature and limited connection to active river channels, supporting consistent aquatic ecosystems. Beels represent larger, often perennial marshy depressions or shallow lakes that form in low-lying areas, frequently fed by river overflows or , and are distributed across central and eastern , including notable examples like and Arial Beel. These wetlands expand significantly during monsoons but retain water throughout the year in many cases, enabling year-round fisheries that contribute substantially to local livelihoods through capture and culture-based production. Their saucer-like and connectivity to river systems distinguish them from more isolated features, fostering diverse aquatic vegetation and fish assemblages. Jheels, prevalent in northern particularly in , are typically oxbow lakes or semi-natural ponds originating from ancient river bends or constructed reservoirs, serving dual purposes in and . Sites like Kanwar Jheel (also known as Kabartal) exemplify this, forming as a result of the Gandak River's meandering and supporting intensive alongside floodwater storage for in the Indo-Gangetic plains. Distinct from the vast natural depressions of haors, jheels often involve human modification for water management, enhancing their role in regional and .
Wetland TypeFormationSeasonalityPrimary LocationEcological Role
Baor lakes from river meanders and course shiftsPermanent water retentionSouthwestern (e.g., )Stable fisheries habitat, floodplain integration
BeelMarshy depressions from fluvial or river feedsMostly perennial, expands in Central and eastern (e.g., )Year-round , support
Jheel or semi-natural reservoirs from river bends or constructionPerennial, managed for stabilityNorthern , (e.g., Kanwar Jheel) storage, production
Haor (for comparison)Deep saucer-shaped basins from tectonic Seasonal flooding (7-8 months inundated)Northeastern Migratory bird habitat, seasonal agriculture-fisheries

Geographical and Geological Features

Location and Extent

Haors are primarily located in the northeastern region of , spanning districts in the and adjacent areas, including Sunamganj, , Habiganj, , , Netrokona, and . The haor wetlands total approximately 1.99 million hectares (19,900 km²) across 373 individual haors in the . The core haor basin, also known as the basin, covers about 20,000 km², representing a significant concentration of these saucer-shaped depressions. This core area is integrated into the larger , where seasonal inundation defines the landscape. The haors are bounded to the north and east by the hill ranges of Indian states, including , , , , and , which influence water inflows from upstream catchments. To the south, their extent is limited near the system, with natural levees and highlands marking the western edges. Key examples include , the largest at approximately 18,000 hectares, situated in and districts (roughly 24°35′–24°45′ N, 92°00′–92°08′ E), and , covering about 9,727 hectares in (approximately 25°09′ N, 91°04′ E).

Formation and Geology

Haors in northeastern originated through a combination of tectonic and fluvial within the Indo-Burman fold belt, primarily during the Pleistocene-Holocene periods. The Basin, part of the larger Bengal Basin where haors are located, experienced accelerated rates—three to eight times higher—from the to Pleistocene, driven by the advancing Indo-Burman ranges and associated dynamics. This , continuing at 3-6 mm per year, formed bowl-shaped depressions characteristic of haor topography, influenced by north-trending folds from the Indo-Burmese ranges such as the Hills. Tectonics in the Meghna Basin played a pivotal role, with differential uplift of surrounding hill ranges—including the to the north, , , , and —creating enclosed lowlands prone to sediment accumulation. The Meghna , spanning approximately 69,514 km² with about 33% in , is drained by the Surma-Kushiyara river system, which facilitated fluvial processes that deepened these depressions through . Haors exhibit low-lying , with elevations typically ranging from 5 to 20 meters above , 80% of the region below 10 meters, and 35% below 5 meters, making them highly susceptible to infilling. Geologically, haors consist predominantly of alluvial silts and clays derived from Himalayan erosion, transported via major river systems and deposited as grey silty clay loams. Over time, during the , ancient river courses from the Brahmaputra and rivers underwent shifts and channel abandonment, leading to the development of backswamps that evolved into the expansive haor wetlands. This fluvial evolution, combined with ongoing tectonic activity, has resulted in a dynamic sedimentary environment of deltaic and deposits spanning post-Oligocene to recent times.

Climate and Hydrology

Monsoonal Climate

The haor wetlands of northeastern are characterized by a , classified under the Köppen system as Am, marked by distinct wet and dry seasons driven by the South Asian system. This regime features heavy annual rainfall ranging from 3,000 to 5,000 mm, with the majority—approximately 70-80%—concentrated during the monsoon period from June to , when southwest winds bring moist air from the . The intense seasonal precipitation in this period triggers widespread inundation across the low-lying haor basins, transforming the landscape from drylands to expansive wetlands. Temperature patterns in the haor region exhibit significant seasonal variation, with cooler winter months from December to February recording averages of 10-15°C, often accompanied by and low . In contrast, the pre-monsoon summer period from to May sees temperatures rising to 25-35°C, fostering hot and humid conditions that precede the rains. Year-round high , typically exceeding 80%, persists due to the proximity to the and the region's flat topography, which traps moisture and exacerbates discomfort during both dry and wet seasons. Regional plays a crucial role in amplifying rainfall over the haors, as the southwest winds encounter the Plateau's southern slopes, leading to that enhances intensity in the adjacent basin. This mechanism results in some of the highest rainfall totals in , with the Meghalaya hills acting as a barrier that forces moist air upward, condensing into heavy downpours that directly influence haor . Long-term climate trends indicate increasing variability in haor rainfall patterns, attributed to global , with observed anomalies showing more frequent and intensified extremes from 1980 to 2020. Studies from 1980 to 2020, extended by projections to mid-century, reveal upward trends in annual totals alongside heightened pre-monsoon variability, leading to erratic wet spells and dry intervals that challenge the region's seasonal predictability; recent events, such as severe floods in June 2024 and October-November 2025, illustrate this trend.

Flooding Patterns

The flooding of haors is driven by overflows from the Surma-Kushiyara and systems, which during the peak season submerge 80-100% of the haor area to depths of 5-7 meters. This mechanism results from heavy upstream runoff and river overbank flows, transforming the low-lying bowl-shaped depressions into vast shallow lakes. Monsoonal rainfall acts as the primary trigger, intensifying the river discharges that spill into the haor basin. The annual hydrological cycle follows a distinct seasonal progression. From November to May, during the dry season, floodwaters recede significantly, exposing expansive mudflats that dominate the landscape and allow for agricultural preparation. Inundation commences rapidly in April-May through initial local rains and early spills from the Surma-Kushiyara system, escalating to full coverage by June that persists through October or November. Recession then occurs gradually from December onward, influenced by evaporation, seepage, and outflow back to the rivers. Haors are characterized by freshwater dominance, with supporting diverse and due to the influx of riverine inputs. Post-monsoon is slow, occurring primarily via natural canals and rivers, which facilitates the deposition of nutrient-rich sediments—estimated at around 13 million tons annually from the Meghna system—enhancing soil fertility for subsequent dry-season cropping. Infrastructure developments have significantly modified these natural patterns. Embankments and gates, intended to control flooding and enable pre-monsoon harvesting, often lead to prolonged water retention, exacerbated , and reduced efficiency. For example, the Haor Rehabilitation Scheme, initiated in 2007, has rehabilitated 37 haors with such structures and river dredging, while the Pre-Monsoon Flood Protection and Drainage Improvement Project, started in 2010, targets an additional 15 haors, altering flow dynamics and contributing to local waterlogging issues. The ongoing Integrated Master Plan for Haor Areas by the Haor and Wetland Development Board continues to refine these interventions to balance with ecological needs.

Ecology and Biodiversity

Flora and Vegetation

The haor wetlands of support a diverse array of plant life adapted to the region's pronounced seasonal flooding, with aquatic and semi-aquatic species dominating the ecosystem during the inundation period. Dominant aquatic includes free-floating plants such as water hyacinth (Eichhornia crassipes), which proliferates rapidly in nutrient-rich waters, alongside rooted floating species like water lilies ( spp., including N. nouchali and N. stellata) and (), which form extensive mats in shallow to deep waters and contribute to oxygen levels and structure. Emergent and riparian vegetation thrives along levees, kandas (elevated lands), and dry-season grasslands, providing stability to the basin edges. Key species here encompass hijal (Barringtonia acutangula), a swamp tree that anchors flood-prone areas and supports cycling, koroch (Pongamia pinnata), which occurs in elevated zones and aids soil stabilization, and reeds (Phragmites karka and related Phragmites spp.), forming dense stands in marshy transitions that buffer wave action and sediment deposition. Vegetation in haors exhibits distinct zonation patterns influenced by water depth and seasonal hydrology, with deep-water zones favoring floating plants like water hyacinth and that cover open waters, while shallow-water areas support submerged species such as Hydrilla verticillata and emergent sedges. During the , many aquatic plants undergo die-off, releasing that enriches the and fuels primary for the subsequent flood cycle. These zonation dynamics create layered communities, from open-water hydrophytes to riparian swamp forests dominated by hijal and koroch. Haor flora encompasses over 200 across diverse habitats, including herbs, trees, and shrubs, with surveys documenting 164 in and 76 in Medir Haor, among others; certain orchids, such as those in the Habenaria genus, represent notable endemics adapted to moist, shaded understories. Recent assessments up to 2021 indicate declines in native diversity due to like water hyacinth and noxious weeds (Mikania cordata), which outcompete locals and alter community structure. These assemblages briefly underpin faunal habitats by offering shelter and foraging bases.

Fauna and Wildlife

The haor wetlands of support a rich diversity of species, with over 140 indigenous species recorded across major sites such as and , belonging to 35 families and 12 orders. Key groups include carps like ( rohita) and ( catla), prawns such as the giant freshwater prawn (), and migratory species including hilsa (Tenualosa ilisha), which undertake seasonal journeys to spawn in the haor's interconnected river systems. These thrive in the haor's flooded basins, where peak breeding occurs during the season from May to October, facilitated by rising water levels that create expansive breeding grounds. Avifauna in the haors is equally diverse, with approximately 208 bird species documented in areas like Tanguar Haor, of which about 50% are migratory and utilize the wetlands as critical stopover sites along the Central Asian Flyway. Prominent species include egrets (Egretta spp.), kingfishers (Alcedo atthis and others), herons (Ardea spp.), and ducks such as gadwall (Mareca strepera), which congregate in large winter flocks numbering up to 60,000 individuals across haor complexes during the non-breeding season from November to March. Although Siberian cranes (Grus leucogeranus) have been reported in broader Bangladeshi wetlands, their sightings in haors are rare and sporadic, reflecting overall declines in this flyway. Other vertebrates adapted to the haor's aquatic-terrestrial interfaces include amphibians like the common skittering frog (Euphlyctis cyanophlyctis) and (Hoplobatrachus tigerinus), with 11 species recorded; reptiles such as the vulnerable peacock softshell turtle (Nilssonia hurum) and various snakes including the (Fowlea schnurrenbergeri); and mammals like the endangered (Prionailurus viverrinus) and the rare (Lutrogale perspicillata), totaling 19 species in surveyed haors. These species rely on the haor's emergent vegetation for shelter and , bridging aquatic and riparian habitats. Fish populations in the haors have experienced significant declines, with species availability dropping by approximately 30-40% in sites like from 2008 to 2018, attributed to and habitat alterations. Overall, more than 40% of species in these wetlands are now classified as threatened nationally by the IUCN, including several carps and the hilsa. The (Platanista gangetica gangetica), listed as endangered globally by the IUCN, is occasionally sighted in haor-connected river channels, underscoring the interconnectedness of these ecosystems.

Conservation and Threats

Haor wetlands in Bangladesh face significant conservation challenges, with key protected areas including Tanguar Haor, designated as a in 2000 and an Ecologically Critical Area (ECA) in 1999 due to overexploitation of resources. Hakaluki Haor, another vital haor ecosystem, was declared an ECA in 1999 to safeguard its , though its formal Ramsar designation remains under process as of 2025. These designations highlight the international and national recognition of haors as critical freshwater ecosystems supporting migratory birds and fish spawning grounds. Conservation efforts emphasize community-based management, led by the International Union for Conservation of Nature (IUCN) in partnership with the government. In , co-management models involving local communities have been implemented since the early 2000s, promoting sustainable resource use and livelihood improvements, with ongoing evaluations as recent as 2025 assessing community participation and ecological outcomes. In May 2025, UNDP and the Ministry of Environment, Forest and Climate Change launched a five-year, $4.05 million GEF-funded project to enhance community-based and restore critical habitats in . Complementary initiatives include the establishment of fish sanctuaries, such as the five permanent ones in created in 2011 to protect breeding areas for indigenous species, and similar efforts in like the Baiya Beel sanctuary. projects in the haor basin, including bioengineering with deep-rooted plants like vetiver, aim to stabilize embankments and mitigate erosion, supported by organizations such as the (IFAD). Major threats to haor ecosystems include climate change-induced erratic flooding, which disrupts seasonal inundation patterns and , as observed in the haor basin's vulnerability to flash floods. from upstream dams, such as those on the , reduces water depth and habitat availability by altering sediment flows into . Illegal encroachment for agriculture and settlements fragments areas, while from pesticides and fertilizers contaminates water bodies, exacerbating . Projections indicate that up to 20% of 's land, including haor s, could be inundated by 2050 due to sea-level rise and intensified flooding, leading to substantial habitat loss. The policy framework for haor conservation is guided by Bangladesh's commitments under the , joined in 1992, which supports wise use and international cooperation for wetland protection. Domestically, the Environment Conservation Act of 1995 (amended 2010) provides legal backing for ECAs and prohibits destructive activities in critical wetlands, complemented by national strategies like the Bangladesh Delta Plan 2100 for climate-resilient management. Although a dedicated National Wetland Policy remains in draft form, these instruments facilitate ongoing updates and community involvement in conservation.

Human Interaction

Settlements and Population

The haor regions of , primarily encompassing seven districts in the northeastern part of the country—Sylhet, Sunamganj, Habiganj, Maulvibazar, Netrokona, , and —feature clustered rural settlements that reflect adaptations to the area's flood-prone landscape. Villages, often referred to as haor-bashi communities, are typically situated on natural levees along rivers or on raised earthen mounds known as chars, which provide elevation above the seasonally inundated lowlands. These compact, nucleated or patterns avoid the deeply flooded basins, with over 90% of the haor land submerging annually during the season, compelling residents to prioritize higher ground for habitation. The of the haor basin is estimated at approximately 22 million as of 2025 projections, representing about 12.6% of Bangladesh's total and exhibiting high density averaging around 987 per square kilometer across the districts, though varying by zone (e.g., 722 per km² in Sunamganj to 1,593 per km² in ). This demographic is ethnically diverse, dominated by who form the majority, alongside indigenous groups such as the Khasi in and Maulvibazar districts and the Garo in Netrokona and areas, reflecting historical intermingling in the environment. Household sizes average 5.3 persons, with roughly 52% of households owning , underscoring the rural character of these communities. Historical habitation in the haor basin dates back to pre-15th century periods, with early settlements established by tribal groups and Hindu communities drawn to the fertile wetlands for and . A significant Muslim influx occurred from the 14th century onward, particularly following the arrival of Sufi missionaries like in around 1303, which facilitated Islamization and further population growth. Migrations were often driven by environmental pressures, including recurrent floods and famines; for instance, the 1787 earthquake along the Dauki fault altered the Brahmaputra River's course, exacerbating subsidence and creating additional low-lying haor depressions that influenced settlement shifts and displacement. These patterns of movement, combined with cyclical environmental stressors, have shaped the region's demographic resilience over centuries. Recent events, such as the 2024 flash floods, have displaced thousands and heightened vulnerabilities in these communities. To cope with annual inundation that affects over 70% of residents through flash floods and prolonged submersion, haor communities employ adaptation strategies centered on elevated housing structures called machans—raised platforms built on or mounds using and earth to protect against water levels rising up to several meters. Seasonal relocation is common, with families moving and belongings to higher chars during monsoons, while homesteads incorporate flood-resilient designs like embankments and green belts for . These measures, though effective for survival, highlight ongoing vulnerabilities, as population pressures continue to encroach on limited elevated land, prompting calls for enhanced like eco-village platforms to safeguard against intensifying impacts. The 2024 floods further strained these adaptations, damaging homes and across multiple districts.

Economy and Livelihoods

The economy of haor regions in northeastern is predominantly driven by fisheries, which form the backbone of local livelihoods due to the wetlands' rich aquatic ecosystems. These areas contribute approximately 20% of the country's inland production, yielding around 260,000 metric tons annually, primarily through dry-season aquaculture and monsoon-season open-water capture fisheries. For instance, alone produces about 15,000-17,000 tons per year, supporting small-scale fishing communities that rely on species like carps and for both subsistence and commercial markets. This sector not only provides essential protein but also generates income, with growth of over 12% observed in recent years through enhanced stocking and practices. The 2024 flash floods significantly reduced yields due to and disruption. Agriculture complements fisheries, with boro rice cultivation being the primary activity during the on raised earthen beds (known as "chaors") to mitigate flooding risks. These wetlands account for 25% of Bangladesh's total boro rice output and 15% of the nation's annual rice production, with average yields ranging from 4 to 5 tons per depending on variety and farm size. Varieties like BRRI dhan28 and BRRI dhan29 are commonly grown, supplemented by rearing in flooded paddies for eggs and , as well as on peripheral lands for diversified income. Local communities, numbering in the millions, depend heavily on these activities for sustenance amid seasonal constraints. However, the 2024 floods devastated boro crops, leading to widespread losses and food insecurity. Additional resources from haors include (kash) harvesting for roofs and crafting materials, which provides seasonal , alongside collection from wild bee populations and emerging initiatives like cage culture for high-value . However, challenges persist, including declining and crop yields due to of resources and increasing climate variability, such as erratic monsoons and early flash floods that disrupt harvesting. rates in haor communities remain high at 40-50%, exacerbating vulnerability and limiting .

Tourism and Cultural Significance

The haor wetlands of , particularly Tanguar and Hakaluki Haors, have emerged as key attractions for nature-based tourism, drawing visitors primarily during the winter months for opportunities. These Ramsar-designated sites host over 200 species of migratory birds, transforming the dried basins into vibrant spectacles that attract ornithologists and eco-tourists from across the country and abroad. safaris, often conducted via traditional houseboats equipped with modern amenities, allow visitors to navigate the expansive waterways, offering close encounters with the haor's unique and . Eco-lodges and floating accommodations in provide sustainable stays, emphasizing low-impact experiences amid the seasonal transformations from flooded basins to grassy meadows. Tourism infrastructure includes designated cruise routes and access points in Tanguar and Hakaluki Haors, supported by government initiatives for . In 2025, visitor numbers to these haors have reached over 100,000 annually, fueled by weekly influxes of 200 to 300 tourist boats carrying multiple passengers each. The government's protection orders, issued in November 2025, prohibit activities like bird hunting and tree cutting to safeguard ecosystems while promoting regulated . These efforts contribute approximately 1-2% to the regional GDP through related services, with plans for expanded eco-friendly facilities to balance growth and conservation. Culturally, haors hold profound significance in local and , embodying resilience against seasonal floods through vibrant folk traditions. Haor songs and dances, often performed during community gatherings, narrate tales of riverine life and agrarian cycles, preserving oral histories unique to these wetlands. Festivals like , the harvest celebration marking the new aman rice crop in late autumn, feature communal feasts, music, and rituals that highlight the haor's agricultural heartbeat, drawing participants to share fresh produce and . Religious sites, including Hindu temples perched on elevated mounds to withstand monsoonal inundations, serve as spiritual anchors for communities, fostering interfaith harmony. Indigenous crafts from Khasi communities in the haor basin, such as weaving and traditional mats, reflect ancestral skills passed down generations, often showcased in local markets and cultural exchanges. Post-COVID recovery has spurred growth in the haors, with increased domestic boosting local economies, yet it raises concerns over and environmental strain. Initiatives for on houseboats and visitor education aim to mitigate risks like in sensitive bird habitats, ensuring the haors' cultural and ecological integrity for future generations.