Hugli Research Articles

On the evidence of the Irrawaddy Dolphin Orcaella brevirostris (Owen, 1866) (Mammalia: Cetartiodactyla: Delphinidae) in the Hooghly River, West Bengal, India

We report the presence and status of the Irrawaddy Dolphin Orcaella brevirostris in the Hooghly River of West Bengal, India. These observations were made while conducting our field work on the Ganges River Dolphin, which involved vessel-based surveys as well as intensive monitoring from an anchored boat.

CO2 effluxes from an urban tidal river flowing through two of the most populated and polluted cities of India.

Urbanized rivers flowing through polluted megacities receive substantial amount of carbon from domestic sewage and industrial effluents which can significantly alter the air-water CO2 flux rates. In this regard, we quantified the partial pressure of CO2 in the surface water (pCO2(water)), air-water CO2 fluxes, and associated biogeochemical parameters in the Hooghly River, India, flowing through two of the most polluted cities of the country, Kolkata and Howrah, over a complete annual cycle during spring tidal phase (SP) and neap tidal phase (NP). This urbanized part of Hooghly River was always supersaturated with CO2 having an annual mean pCO2(water) and air-water CO2 flux of ~ 3800 μatm and ~ 49 mol C m-2 year-1, respectively. Significant seasonal variability was observed for both pCO2(water) and air-water CO2 flux (pre-monsoon, 3038 ± 539 μatm and 5049 ± 964 μmol m-2 h-1; monsoon, 4609 ± 711 μatm and 7918 ± 1400 μmol m-2 h-1; post-monsoon, 2558 ± 258 μatm and 4048 ± 759 μmol m-2 h-1, respectively). Monthly mean pH and total alkalinity varied from 7.482 to 8.099 and from 2437 to 4136 μmol kg-1, respectively, over the annual cycle. pCO2(water) showed significant positive correlation with turbidity and negative correlation with electrical conductivity and gross primary productivity (GPP). High water discharge could have facilitated high turbidity, especially during the monsoon season, which led to depletion in GPP and enhancement in pCO2(water) which in turn led to very high CO2 effluxes. The CO2 efflux rate in this urbanized riverine stretch was substantially higher than that observed in previous studies carried out in the less urbanized estuarine stretch of Hooghly. This indicates that the presence of highly urbanized and polluted metropolis potentially enhanced the pCO2(water) and CO2 effluxes of this river. Similar observations were made recently in some Asian and Australian urban rivers.

Near bank turbulence of a river bend with self similar morphological structures

The shapes of a meandering river at the different stages of its evolution forming meander loops result from the interaction of the turbulent flow structures and channel planform. Based on field investigations and analysis of Google Earth (aerial) images, series of self-similar lobed-shaped patterns of different scales evolving in both space and time were observed at the outer curved bank of large rivers such as Hooghly River (India), Yamuna River (India), Madhumati River (Bangladesh) and in the White Nile (Africa). The present study attempts to develop insight into the turbulence characteristics of the flow leading to the formation, growth and migration of these self-similar lobed-shaped patterns. Measurements of turbulent flow characteristics were carried out at five different locations within a distinct dynamic lobe of an outer bend of the River Hooghly. Results show that the outer bank of a curved channel is under the action of strong secondary currents, turbulent burst-sweep cycles, flow separation and strong intermittent turbulent shear stress at different scales leading to enhanced bank erosion activity. The results from the present study form the basis for a conceptual representation of the bankline retreatment process through the formation, growth and evolution of dynamic lobed-shaped erosive patterns.

A Note on “Metal Distribution and Short-Time Variability in Recent Sediments from the Ganges River towards the Bay of Bengal (India)” by Bonnail et al. (2019)

A careful reading of Bonnail et al. (2019)’s work points out some issues in the description of the Ganges River, e.g., describing it in a way that gives impression to the readers unfamiliar with the Indian rivers that it flows by the national capital New Delhi, after reading “it receives inputs from highly populated cities of India, including New Delhi and …”. However, as a matter of fact, it is not the Ganges, but the Yamuna River, a tributary of the Ganges, that passes through the National Capital Region of Delhi. Moreover, authors identify the studied river as the Ganges, whereas it is one of the distributaries of the Ganges called Hooghly (anglicized version of its local name Hugli). They have referred to the seasonality of the studied river; however, the flow of the studied (Hooghly) river is controlled by a barrage on the Ganges River. Moreover, Hooghly River receives input from its own tributaries; viz., Mayurakshi and Damodar, flowing through highly mineralized and coaliferous areas of Jharkhand state of India. Bonnail et al. (2019) have attributed the contamination of the river sediments to anthropogenic activities alone, by not evaluating likely natural sources. A correction factor for the underestimated total organic carbon (TOC) content obtained using Walkley-Black method should have been applied before using TOC values for factor analysis to overcome the underestimation issue with this method. This work intends to serve as a compendium, rather than a critique, to otherwise commendable work by Bonnail et al. (2019).

Spatial and seasonal distribution of multi-elements in suspended particulate matter (SPM) in tidally dominated Hooghly river estuary and their ecotoxicological relevance.

The present work represented first study of the spatio-seasonal distribution of the multi-elements in the suspended particulate matter (SPM) of the tropical Hooghly river estuary (HRE), eastern part of India. The high load of SPM (20-3460mg/l) might have induced negative impact on the phytoplankton density. The relative abundance of the studied elements exhibited the following decreasing trend (concentration in μg/g and %): Si(26.44 ± 3.75%) > Al(7.94 ± 1.52%) > Fe(6.17 ± 1.9%) > K(3.05 ± 1.5%) > Ca(1.97 ± 1.11%) > Mg(1.57 ± 1.71%) > Na(1.45 ± 8.40%) > Mn(1273 ± 2003) > Zn(178.43 ± 130.95) > V(151.54 ± 27.13) > Cr(147.08 ± 32.21) > Cu(62.06 ± 14.03) > Ni(49.64 ± 12.09) > Pb(21.5 ± 10.45). The accumulation of Ni, Cr, Pb, and Cu is mainly controlled by the formation of Fe hydroxides along with particulate organic carbon (POC) and salinity. The average geo-accumulation index (Igeo) and enrichment factor (EF) endorsed the substantial input of Cr (Igeo = 0.037; EF = 1.61) and Zn (Igeo = 0.123; EF = 2.07) from diffused pollution sources. From ecotoxicological point of view, the quality guidelines (QGs) suggested that Cr and Ni might possess frequent adverse biological effects. However, the mean probable effect level (PEL) quotient values revealed 49% probability of toxicity to the aquatic biota for five toxic elements (Cr, Ni, Cu, Zn, and Pb). The geochemical approaches, pollution indices, and statistical evaluation together revealed low to moderate contamination in the estuary. This baseline data would be beneficial in adopting proper management strategies for sustainable utilization and restoration of the water resources. The authors strongly recommend continuous systematic monitoring and installation of treatment plants for management of this stressed estuary.

A preliminary study on upstream migration of mangroves in response to changing environment along River Hooghly, India

Environmental changes and anthropogenic activities can be linked to altered distribution and abundance of species. However, the ecological impacts of change in the microenvironment have not been well documented. Herein, we have identified the distribution of mangroves and associated species and characterized surface sediment and water samples along the banks of River Hooghly. The application of Combined Mangrove Recognition Index (CMRI) and its validation with the available ground data on satellite image of 2015 indicates that some mangrove species have reclaimed the upper course of the river, which was earlier absent before 1995. This study is the first report on the upstream migration of mangrove species such as Sonneratia caseolaris, Sonneratia apetala, Derris trifoliata, Hibiscus tiliaceus, and Thespesia populnea in River Hooghly. The changes in pollution load, varied sedimentation pattern, high chemical oxygen demand, mean sea-level rise, and anthropogenic activity might have played a significant role in the upstream migration of mangroves.

Open-angle glaucoma in a rural and urban population in Eastern India—the Hooghly river glaucoma study

Purpose:Glaucoma is the leading cause of irreversible blindness in the world. The current study aims to estimate prevalence, features, and associations of open angle glaucoma (OAG) in a rural and urban East Indian population.Methods:This is a population based cross sectional study with two arms, rural (28 contiguous villages from 13 Gram Panchayats in Balagarh Police Station, Hooghly district) and urban (Kolkata). Individuals residing in the study area aged 40 years and above were included using multistage random cluster sampling. All subjects underwent a detailed ophthalmic examination at our base hospitals including applanation tonometry, ultrasound pachymetry, gonioscopy, and frequency doubling technology perimetry. The primary outcome was the prevalence of POAG (95% CI). Age and gender specific prevalence estimates were calculated. Multiple logistic regressions were used to analyze the risk factors.Results:Data from 7128 and 6964 subjects aged 40 years or older from Kolkata city and Hooghly district, respectively were analyzed. In the urban population, 2.10% (95% CI: 1.99–2.21%) had POAG and 0.15% (95% CI: 0.13–0.17%) had secondary OAG. In the rural population, 1.45% (95% CI: 0.59–2.31%) had POAG and 0.10 ± 0.03% (95% CI: 0.07–0.13%) had secondary OAG.Conclusion:The study concludes that higher age, higher vertical cup disc ratio (VCDR), and lower central corneal thickness (CCT) are important independent predictors of OAG and emphasizes that increased intraocular pressure (IOP) is not POAG. Gonioscopy, disc evaluation, and screening perimetry need to be incorporated in the detection protocol for glaucoma if we intend to lighten the burden of blindness due to glaucoma.

Spatial distribution and sources of pesticidal persistent organic pollutants in the Hooghly riverine sediment.

Given the extensive indiscriminate usage in the past and limited ongoing use, organochlorine pesticides (OCPs) have been widely reported in the Hooghly riverine environment. Hence, surface riverine sediment samples were collected along the urban and suburban transects of the Hooghly River and OCPs were quantified in gas chromatography mass spectrometry (GC-MS). Mean concentration of HCH, DDT, and endosulfan was 5ngg-1, 10ngg-1, and 4ngg-1 respectively. DDT was dominant among all the OCPs and contributed nearly 40% to the total OCPs possibly due to the ongoing use of DDT for vector control programs. Diagnostic ratios suggest recent source of lindane, DDT, and endosulfan. Using OCP concentration from previously published data in surface water during the same time frame, sediment-water partitioning of OCPs was estimated. Excluding α-HCH and γ-HCH in few pockets, majority of the OCPs tend to partition more on to sediment. Comparing the sediment concentration with the sediment quality guideline values, risk on ecological integrities was indicated due to DDT and HCH contamination. Suburban sites indicated higher risk than urban sites according to the calculated sediment quality guideline quotient (SQGQ). A brief review on the approach to pesticidal POP pollution management in India revealed that older management approaches should be replaced with a unique, integrated, and holistic system.

Sewage fluxes and seasonal dynamics of physicochemical characteristics of the Bhagirathi-Hooghly River from the lower stretch of River Ganges, India

ABSTRACTTo understand the temporal variations of the physicochemical characteristics of the Bhagirathi-Hooghly River (BHR), three locations representing three districts of West Bengal were selected. The material fluxes from 34 drains during pre-monsoon season was quantified. The analysis of variance (ANOVA) revealed that no significant spatial variations were observed for the physicochemical parameters, whereas seasonal variations were significant. The mean discharge was found to be highest (247.2 × 103 m3 d−1) in the midstream drains. Highest mean concentrations of dissolved oxygen (DO) (7.35 mg L−1) and nitrate (0.81 mg L −1) were observed during the post-monsoon season followed by the monsoon and pre-monsoon. According to the BIS, WHO and the European standard of water quality (pH, 6.5–8.5; Nitrate, 0–2.5 mg L−1;DO, ≥5 mg L−1), the results of the respective parameters revealed the BHR system is maintained at high to good water quality, meaning that the BHR system is slightly altered from its pristine environment. The mean concentrations of biological and chemical oxygen demands were found to be high during the monsoon season, revealing that a large quantity of refractory organic matter is transported to the eastern Bay of Bengal from the Ganges.

Geochemical fractionation and risk assessment of trace elements in sediments from tide-dominated Hooghly (Ganges) River Estuary, India

The geochemical fractionation and potential mobilization of cadmium, chromium, copper, nickel and lead were studied in surficial sediments (top 0–10 cm; <63 μm grain-size) of the Hooghly (Ganges) River Estuary, eastern part of India, using a sequential extraction procedure. The risk assessment was evaluated at three specific levels; i.e., enrichment level (enrichment factor, geo-accumulation index), the availability level (elements bound to different fractions, risk assessment code, Individual and Global contamination factors) and biological toxicity level (Potential ecological risk index; sediment quality guidelines). Different geochemical phases indicated heterogeneities in TE distribution patterns as follows: (i) Cd was dominant in the exchangeable phase and significant proportion of Pb was bounded to the reducible fractions; (ii) the potential mobile fraction (ΣF1 − F3) in the sediments was higher for Cd and Pb (>46%), reflecting their adverse impact on benthic organisms as they are weakly bound to the sediment and can migrate to water; (iii) a minor fraction of Cu (<10%) was found in the oxidizable fraction suggesting less environmental risk to the aquatic biota and (iv) the dominance of the Ni, Cr and Cu in the residual fraction supports the assumption of their geogenic origin. Both Cd and Cu posed medium to high ecological risk values based on risk assessment code (RAC). Global Contamination Factor (GCF) values allowed to identify the “pollution hotspots” in the study area.

History of the subterranean connections between Calcutta and Howrah

The first metro railway started operation on London’s Metropolitan Railway line using steam locomotives and wooden carriages (1863). Although Calcutta, India, acquired its metro in 1984, its connection with Howrah through an underwater tunnel under the River Hooghly was first conceived in 1921. Plans for this were laid out by Sir Harley Dalrymple-Hay, and he prepared the blueprint of a railway from Calcutta to Howrah with ten stations over its 10·6 km stretch. Unfortunately, the project was abandoned by the government of Bengal on financial grounds. Then, in 1928, Calcutta Electric Supply Corporation, to cater for increasing power demand on both sides of the river, consulted Sir Dalrymple-Hay to provide a tunnel below the lowest scour level of the river. It was planned to provide a conduit for electrical cables with inspection facilities, and this tunnel was built in 1931. Calcutta’s East–West metro line, including the underwater stretch below the River Hooghly, was reconceived in 2006, and construction started in 2009. This line now crosses the River Hooghly with a rail level at a depth of 19 m below the riverbed with 13 m of water depth at average tide, and its projected daily commuters will be almost 1 million by the year 2035.

Impact assessment of barge trafficking on phytoplankton abundance and Chl a concentration, in River Ganga, India.

Impact of barge movement on phytoplankton abundance and biomass was assessed in the lower stretch of river Ganga, popularly known as Bhagirathi-Hooghly river, during April 2016 to March, 2017. Based on the magnitude of tide, intensity of shipping and boating activities, the stretch from Baranagar to Lalbag (278 km), located at latitude (22°38'33.41"N to 24°10'59.75"N) and longitude (88°21'21.29"E to 88°16'5.65"E) was divided into three zones viz. zone—I (Baranagar to Barrackpore), zone II (Triveni to Balagarh) and zone III (Nabadweep to Lalbag). Water samples were collected randomly from six stations covering 22 barge movements at their passage at three different time intervals viz., 30 minutes before ‘barge movement’, during ‘barge movement’ and 30 minutes after ‘barge movement’. Analysis revealed the presence of 52 phytoplankton taxa belonged to 5 phylum during the study period. The abundance of phytoplankton was highest in zone—I followed by zone III and the zone II. A 44% decrease (1,997 ±1,510 ul-1) in phytoplankton abundance was observed during ‘barge movement’ with respect to normal condition (3,513 ± 2,239 ul-1) which could be due to propeller turbulence in the passage. Cell damage study revealed 21% damage in phytoplankton cell structure in ‘during barge’ followed by ‘after barge’ (10%) condition compared to natural state (6%). Study revealed that phytoplankton biomass (Chlorophyll a) was influenced by ‘barge movement’ in the sampling stretches and the impact was assessed by one way ANOVA. The effect was found significant at Barrackpore (p <0.01), Triveni (p <0.01), Balagarh (p <0.01) and Lalbag (p <0.01) where as it was insignificant at Baranagar and Nabadweep, which may be due to continuous and existing boat trafficking at Baranagar and Nabadweep. Two way ANOVA computed using ‘barge movement’ and sampling stations showed significant (p<0.01) effect on magnitude of Chl a concentrations in the sampling locations. Thus, the ‘barge movement’ influenced phytoplankton abundance and biomass, it had a detrimental effect on phytoplankton cell architecture also. The data set of this work serves as foundation information to understand the ecological implications augmented barge induced environmental disturbances in waterways. This is the first such study which depicts the impact of ‘barge movement’ on aquatic food chain linkages in Bhagirathi- Hooghly river.

Elemental composition of aquaculture fish from West Bengal, India: nutrition versus food safety.

Aquaculture production continues to grow in West Bengal, where on average people consume 8.2kgcapita-1 of fish each year, and an extensive mosaic of aquaculture ponds has developed along the River Hugli as clay pits are repurposed. The adjacent brickworks and industry (especially tanneries) are a source of environmental pollution, with potential for bioaccumulation of potentially harmful elements (PHEs) in fish farmed in these ponds. Fish from aquaculture present an opportunity to meet food sufficiency in West Bengal; however, an investigation to assess their effectiveness for micronutrient supply balanced against food safety is required. Five ponds close to industrial brick manufacture (urban) and three from rural areas were assessed for the degree of pollution within their pond sediments and waters. Fish were also sampled from each location including a subset from the market in Kolkata to determine the concentrations of PHEs in their fish muscle tissue. Dietary intake and PHE loading were calculated for four fish species to evaluate their nutrient content with respect to recommended daily intakes for adults, e.g. calcium (Ca), potassium (K), magnesium (Mg), iron (Fe), zinc (Zn) and selenium (Se), and to establish whether the provisional maximum tolerable intakes (PMTIs) are exceeded for PHEs, e.g. aluminium (Al), arsenic (As), mercury (Hg), chromium (Cr), tin (Sn), copper (Cu) and lead (Pb). Preliminary results suggest that aquaculture is making an important contribution to nutrition, with fish being a good source of Se. However, in contrast to small wild-caught fish, aquaculture fish in the present study were poor sources of Fe, Ca and Zn. The fish also made substantial contributions (> 10%) to the PMTI of Hg and As. Therefore, there is an urgent need for ongoing monitoring and an expanded sampling programme, as well as research into approaches which might improve the nutritional quality of the farmed fish.

Calcutta’s Pulta Water Works: 150 years of silent service

Calcutta (Kolkata) served as the capital of colonial India from 1757 to 1911. It fundamentally resembled the urban setting of London. For over three centuries since its inception as an urban centre, Calcutta observed huge growth, endured political events, survived disasters, absorbed the influx of refugees and is now one of the most congested cities in the world. Prompted by its growth as a regional hub in the early nineteenth century and recognising the pressing need for an organised water supply system, the authorities started implementation of the very first surface-water-based supply scheme in Asia. Despite being situated next to River Hooghly, Calcutta’s water supply was designed to draw water from 22 km upstream. Pulta Water Works started operation in 1868 with only 27·3 million litres per day (mld) capacity, having simple water abstraction, treatment, supply, storage and distribution techniques. Now, this waterworks has an installed capacity of 1182 mld and employs advanced treatment technologies to serve more than half of the larger city area. This paper summarises the history of inception and development of Pulta Water Works, which still serves Calcutta and stands out as an emblem of sustainable urban water supply.

Consequences of sand mining on water quality and instream biota in alluvial stream: a case-specific study in South Bengal River, India

In this paper, an attempt has been made to document consequences of river sand mining on water quality and instream biota in an alluvial channel as Kangsabati River, India. Water Quality Index (WQI) is used to identify the adverse effects of water quality on species diversity, richness, and evenness of the aquatic community. Physicochemical parameters (PP) such as pH, dissolved oxygen, total dissolved solids, electric conductivity, salinity, biological oxygen demand, magnesium cation, and turbidity are analyzed from 27 representative sampling stations as sandchar, mining, and pit sites along the upper, middle, and lower course. Pearson correlation indicates that pH and magnesium cation is the most significant parameters with WQI. Principal component analysis denotes good water quality ( 70) water qualities are presence in mining and pit sites. Applying Simpson’s index, Simpson’s index of diversity, Simpson’s reciprocal index, and Shannon–Wiener diversity index on instream biota, those vary from sandchar (0.19, 0.81, 5.57, and − 1.34) to mining (0.11, 0.89, 9.23, and − 1.39) and pit sites (0.12, 0.90, 10.68, and − 1.50). Maximum Margalef’s index of species indicated the richness of species types in mining sites (4.62), with minimum mean values in sandchar sites (3.64). Contrastingly, Pielou’s evenness index is high in sandchar sites (− 1.05) and low in mining sites (− 1.49). Therefore, significant physicochemical parameters such as PH, dissolved oxygen, magnesium cation, and electric conductivity changes the diversity index, species richness and evenness in mining and pit along the middle and lower courses caused by sand mining.

Urban Growth Dynamics and Changing Land-Use Land-Cover of Megacity Kolkata and Its Environs

Spatio-temporal land-use land-cover changes have a long-term impact on urban environments. The present study is based on land-use land-cover changes and urban expansion of megacity Kolkata and its environs over three decades (1991–2018) using multitemporal Landsat data. The study aims to explore and explain the spatio-temporal land-use land-cover change, areal differentiation, spatio-temporal urban growth trajectory and future land-use land-cover prediction with population projection. The spatio-temporal representation found rapid urbanization, i.e. 19% to 57%, exactly three times as in 1991, resulting in significant loss of other than urban/built-up area. Urban trajectory reveals that the expansion mainly occurred in north-east to south-west direction, the zone of both sides of River Hooghly. Areal differentiation map with highest urbanization (3146 ha or UII = 0.64) was identified in the north–north-west part, while least urbanization was identified in the east–north-east direction. On the other hand, this urbanization has grabbed most (i.e. 87%) of the areas within 5-km ring buffer compared to other three ring buffers. Being Kolkata as a traditional city, it has all modern facilities since British rule; as a result, the high population growth and rapid urban expansion were explored in the study. Therefore, urban growth led to radical changes in land-use land-cover, which were witnessed by sharp decreases in sparse vegetation and fallow land. The correlation explained that increasing urbanization has decreased the amount of water body and vegetation. The future prediction graph identified the more horrible picture: the city and its environs will be covered by 67% built-up, while there will be only 3% water body, 14% vegetation and 16% fallow land of the total geographical area with a population (projection) of 28 million in 2051 if it is continued. Such expansion will create a wide range of mismanagement and environmental problems. Hence, the intensive explanation and areal differentiation maps and diagrams prepared using geospatial data will definitely help to understand the urban growth dynamics process and changing form of land-use land-cover and simultaneously decision-making process of the local planners, stakeholders and academicians. Therefore, it also guides to future planning to decrease the adverse effects of urbanization and result in the form of land-use land-cover and makes an eco-friendly megacity as well as sustainable urban development too.

Distribution and sources of organic contaminants in surface sediments of Hooghly river estuary and Sundarban mangrove, eastern coast of India

This study investigated polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds such as polychlorinated biphenyls (PCBs) and DDT-related pesticides in surface sediments of Hooghly estuary and the Sundarban mangrove wetlands. Concentrations of ∑17PAH, ∑182PCB and ∑6DDT ranged from 15.4 to 1731, not detected (nd) to 13.5 and nd to 8.97 ng g−1 dry weight, respectively. Low levels of PCBs and low to moderate concentrations of DDTs and PAHs reflected recent development in West Bengal, which was dominated by agriculture and multifarious industries in the past. Diagnostic ratios suggested that major sources of PAHs are combustion processes, DDTs are input by agriculture, antifouling paints and public health campaigns, and organochlorines are predominantly from industrial origin. Heavier PCB congeners suggest local sources and short-range transport of such chemicals. Decision makers may use these findings for managing the Hooghly River watershed in order to promote a sustainable development on the eastern coast of India.

Air-water exchange of pesticidal persistent organic pollutants in the lower stretch of the transboundary river Ganga, India

The lower stretch of the perennial transboundary river Ganga is known as the Hooghly River (HR) in India. Despite the strict ban, HR has been evidenced with residues of pesticidal persistent organic pollutants (POPs) from primary and secondary sources. Hence surface water sampling and passive air sampling (PAS) were conducted along the urban and suburban transects and discharge points to study the fate of pesticidal (POPs along the HR. Excluding the discharge points, the mean concentration of hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and endosulfan (ENDO) were 6 ng/L, 4 ng/L and 36 ng/L in surface water and 888 pg/m3, 1689 pg/m3 and 429 pg/m3 in atmosphere respectively. Percentage composition and diagnostic ratios strongly suggest ongoing use of technical HCH, DDT and endosulfan. Elevated endosulfan in surface water has been related to its usage during fishing. Except for p,p’-DDE, α-Endo and β-Endo, fluxes at the air-water interface showed net deposition from air to water for all the OCPs in urban and suburban transects. The estimated eco-toxicological risk assessment showed risk on lower trophic organisms due to DDT and lindane mostly at the discharge points. Endosulfan can pose potential risk to the edible fishe species in the HR.

Fishers’ Livelihood Diversification in Bhagirathi–Hooghly Stretch of Ganga River in India

For the resource-poor fishers, livelihood diversification is a strategy to cope with the uncertainties and inadequateness of fisheries as a profession. The present study is an attempt to assess the socioeconomic conditions together with livelihood diversification of fishermen households of the Bhagirathi– Hooghly stretch of Ganga River. Data were collected by personally interviewing 500 fishermen from Sagar to Farakka (560 km stretch) in West Bengal using survey schedules in 2016. Analysis of data indicated that the socio-economic conditions of fishermen households were not encouraging. Fishing is the main occupation of around 88.60% of fishers and overall, fishing contributes about 70.30% to the total income of the family. Average number of income-generating activities per household ranged from 1.43 in the lower stretch to 1.79 in the upper stretch. Further, it was found that not only the average household income and number of income sources were limited, their level of diversification was also quite low. The monthly income of a household was found to be Rs 9391. The income is higher in the lower stretch because of higher catch and high value fish in the catch. Fishery as an only profession is unable to provide a decent life. The study also revealed that among other factors, the Simpson index contributes positively and significantly towards per capita income of the fisher households. However, in the absence of suitable alternative opportunities, the resource is under pressure. Government needs to develop appropriate strategies to facilitate successful livelihood diversification. Facilities may be created for non-fishing activities like fish marketing kiosks, cloth weaving facilities, agro-processing in fruit orchard areas, e-rickshaws and so on. Fishers may be trained in other income-generating activities like carpentry, embroidery, dress making, driving, etc. for better livelihood.

River-tide-storm surge interaction characteristics for the Hooghly estuary, East coast of India

ABSTRACT The head Bay of Bengal region that borders the North Indian Ocean is crisscrossed with numerous tidal creeks, riverine systems and channels that play an important role in storm surge studies. In particular, the storm surge resulting from the landfall of tropical cyclone over this region can interact with the river systems and thereby modify the characteristics of storm surge. Several studies were attempted to understand the behaviour of storm surges and associated inundation for the Indian coast; however, the role of hydrologic component in modifying storm surge received less attention. The present study considers a stretch of Hooghly River channel in West Bengal that provides the navigable route to two important national ports, and important in context to socio-economic implications. The state-of-art advanced circulation model (ADCIRC) hydrodynamic model used in this study incorporates the riverine stretch and investigates the effect of river discharge on storm surge propagation along the upstream reaches of the Hooghly River. In addition, the river-tide interaction was studied with differential river discharge volumes of 1000 and 3000 m3 s−1 that corresponds to the respective minimum and maximum discharges. Model simulations well represented the upstream tidal propagation as well the reversal of tidal currents in the river. Also the effect of variable river discharge volumes in modifying the limit of flood flow was clear from simulation. The results signify that limit of flood flow was seen nearly 70 km in the river upstream for discharge volume corresponding to 1000 m3 s−1 and reduced to 62 km on increasing the discharge to 3000 m3 s−1. The effect of wind stress on storm surge penetration into river was also investigated using the hypothetical Aila cyclone wind field. Moreover, the combined effect due to varying river discharge volumes and wind stress on storm surge characteristics was also studied. The study is an effort to understand the role of river-tide-storm surge interaction very useful in a real-time storm surge forecasting system.