Chalakudy River Research Articles

Prediction of streamflow in Chalakudy River Basin, Kerala, by integrating teleconnection patterns of large-scale atmospheric circulations

ABSTRACT In this study, the relationship between large-scale climatic drivers and streamflow of the Chalakudy River Basin, Kerala, was analysed using methods such as bivariate wavelet coherence (BWC), multiple wavelet coherence (MWC), and partial wavelet coherence (PWC) analysis. The four prominent global climate indices chosen are the Indian Ocean Dipole (IOD), North Atlantic Oscillation (NAO), El Niño Southern Oscillation (ENSO), and Pacific Decadal Oscillation (PDO), along with other local climate drivers. The BWC analysis showed that streamflow and rainfall had a very strong in-phase relationship, whereas the maximum temperature and average temperature showed an anti-phase relationship. In the case of global climate drivers, ENSO has a significant impact on the streamflow of the Chalakudy River Basin. The average wavelet coherence (AWC), which quantifies the teleconnections, confirms the observation with a high coherency of 0.75 between streamflow and rainfall and 0.51 for streamflow and ENSO. Streamflow prediction models were developed using random forest (RF) and artificial neural network (ANN) techniques by considering the influence of significant global and local climatic drivers. It was observed that the RF model performed slightly better than the ANN model, with R = 0.875, NSE = 0.766, RMSE = 23.468, and RSR = 0.524.

Otolith shape reveals the population structure of 'Malabar Labeo’, Labeo dussumieri (Valenciennes, 1842), in the four west-flowing rivers of India

Otolith shape variation in Labeo dussumieri from the four west-flowing rivers of India was analyzed using Wavelet coefficients and elliptic Fourier descriptors in the ShapeR package. The mean otolith shape of L. dussumieri varied significantly among sampling locations, with the posterior margin of the otolith showing the maximum variation. Otolith shape analysis also revealed variations between regions of different latitudes, with the northern (Narmada and Kundalika River) and southern populations (Achankovil and Chalakudy River) forming two distinct clusters. This variability in otolith shape might be attributed to the variation in environmental conditions prevailing in the sampling locations. The linear discriminant analysis based on elliptic Fourier descriptors and Wavelet coefficients showed an overall classification success of 89.03 % and 89.20 %, respectively. The present study validated that the lapillar otoliths are ideal for investigating the population structure of cyprinid fishes like L. dussumieri. The present study provided the first comprehensive information on the otolith shape analysis of L. dussumieri from the four west-flowing rivers of India.

Demographics and reproductive characteristics of threatened Malabar pufferfish (Carinotetraodon travancoricus) from Western Ghats hotspot, India

Context Carinotetraodon travancoricus is a threatened ornamental aquarium fish endemic to Western Ghats (WG) biodiversity hotspot of India and indiscriminate collection of this species resulted in a severe population decline. Aims To understand the impacts of wild collection of C. travancoricus for aquarium-fish trade, information on their population status and reproductive characteristics is required. Methods Specimens for the present study were collected from the Chalakudy River of WG and growth, mortality, exploitation and reproductive characteristics of C. travancoricus were investigated. Key results The natural mortality of the species was higher than the fishing mortality. The peak spawning period of the species was from May to September. Length at first maturity (L50) for males and females was estimated to be 18.4 and 18.1 mm respectively. Conclusions The stock of C. travancoricus in the Chalakudy River may be in near full exploitation under current harvesting strategy. The lower value of length of first capture than size at first maturity indicated that C. travancoricus is likely to be captured before it matures and breeds, subsequently contributing to declining recruitment. Implications A combination of different strategies (closed fishing seasons, mesh-size regulation and no-fishing areas) will improve sustainable management and conservation of species.

Resilience in Action: Examining Re-settlement Efforts of Flood-Affected Farmers in the Chalakudy River Basin

The devastation caused by natural disasters, particularly in developing regions with limited resources and infrastructure, poses significant challenges to human lives and livelihoods. The 2018 Kerala floods, one of the worst in the state's history, wreaked havoc across the region, particularly affecting the Chalakudy River basin. This paper explores the resilience and resettlement efforts undertaken by flood-affected farmers in the Chalakudy River basin post-disaster. Drawing on a review of literature and empirical data, the study examines the various forms of assistance received, including emotional rehabilitation support, special loans, and subsidies. The findings highlight the remarkable resilience of the farming community amidst adversity, while also shedding light on disparities in aid distribution and the challenges encountered in the resettlement process.

Aquatic insects for monitoring the health status of riverine potholes: A case study in Chalakudy river basin, Kerala, India.

Potholes are microhabitats in riverine ecosystems that substantially contribute to the unique regional faunal diversity and community composition. Investigations on the ecological status of potholes in riverine habitats are very scanty. The present work is of utmost importance, particularly as a pioneering study to evaluate the health status of riverine potholes using aquatic insects as potential biological indicators. Samples of water and aquatic insects were collected and analyzed during the pre-monsoon season from February 2022 to May 2022 in the potholes at Athirappilly and the Ezhattumugham regions of the Chalakudy river basin.The present study identified 208 individuals represented by 15 families in the potholes at Athirappilly, whereas 94 individuals belong to 10 families at Ezhattumugham.The computation of water quality parameters and benthic metrics revealed a significant variation between the stations.Spearman correlation analysis revealed that the water temperature, electrical conductivity, dissolved oxygen concentration, and biochemical oxygen demand were influencing the distribution of aquatic insects in the potholes. Families such as Perlidae, Ephemeridae, Baetidae, Stenopsychidae, and Hydropsychidae (sensitive families) reported from the well-oxygenated potholes at Athirappilly, where the water temperature and biochemical oxygen demand were minimum.The significantly high percentage composition of Ephemeroptera, Plecoptera, and Trichoptera taxa and a low family biotic index value indicate good health condition of the potholes at Athirappilly. In contrast, the low percentage composition of Ephemeroptera, Plecoptera, and Trichoptera taxa and high family biotic index values, with the abundance of tolerant families (Micronectidae, Caenidae, and Chironomidae), reflect the impact of organic pollution at Ezhattumugham.

Trophic fingerprinting of a pristine but rapidly deteriorating downstream region of a Western Ghats River.

Chalakudy River is renowned for its pristine waters and rich ichthyofaunal biodiversity. The downstream area of the river is confronting a series of risks, including pollution, saline water ingression, sand mining, illegal and intensified fishing practices, and invasion of exotic and alien species. A mass balanced ecosystem model was constructed for the downstream region of Chalakudy River (DCR) using Ecopath with Ecosim (EWE), incorporating 12 functional groups to delineate the food web and network flow indices for the period 2020 to 2021. The trophic level (TL) of the ecosystem network ranged from TL-1 (detritus) to TL-3.4 (birds). High fishing pressure is one possible cause for the high ecotrophic efficiency values as evidenced by the fish groups. Both the grazing food chain and detritus food chain (detritivory: herbivory ratio 0.94) contributed more or less equal to the energy transfer between TL. Network analysis of the model indicated a mean transfer efficiency of 12%, with shares from primary producers (14%) and detritus (11%). A mixed trophic impact analysis demonstrated a strong positive impact of primary producers and detritus groups on most of the other ecological groups at higher trophic levels. The DCR model showed a high system throughput (32,464.7 t km-2 year-1), low system omnivory (0.09), low connectance index (0.36), low Finn's cycling index (4.9), and mean path length (2.8), low relative ascendency (37.5%), and high system overhead (62.5%). These indices propound that DCR is an immature and developing ecosystem with moderate strength in reserve to resist external perturbations.

Characterization of suspended microplastics in surface waters of Chalakudy River, Kerala, India

ABSTRACT The investigation focused on identification and quantification of microplastics in surface waters of Chalakudy River, Kerala. Microplastics were detected in the surface waters of the study area with a recovery rate of 108.33 mg particles L−1. The abundance of microplastics ranged from 15.13 ± 4.13 – 170 ± 17.75 particles L−1 (mean: 55.81 ± 34 particles L−1). A maximum number of microplastics were obtained from site C3 and the least from site C8. The weight distribution of microplastic on sites exhibited strong positive correlation with the abundance (r = 0.83). Microplastics of size <20 µm were in higher abundance in the study area. Microscopic examination revealed fragments (47.06%) as predominant plastics and the dominant colour was brown/mud (26.99%). Abundance of coloured plastics indicated the probability of damage to aquatic life. Raman spectrum analysis revealed that Low-Density Poly Ethylene (40%) as the predominant polymer that could be observed at all the sampling sites. Lower-sized microplastics would cause accidental ingestion by organisms. The estimated release of a higher average number of microplastic particles (55.81 ± 4.25) into the marine environment is of serious concern. The observed overall abundance and recovery rate of microplastics in the study area indicated the status of contamination due to a multitude of sources.

Water Delivery Performance of Canal Irrigation: A Case Study of Chalakudy River Diversion Scheme

The role of irrigation is important in mitigating the challenges involved in food production under the changing climate scenarios. Adequacy and equity in water distribution are the primary concern regarding the performance of any irrigation scheme. Conveyance efficiency and two adequacy indicators, namely, Relative Water Supply and Adequacy were used to evaluate the performance of Chalakudy River Diversion Scheme (CRDS) located in central Kerala, India, in the present study, Water withdrawal data collected from Irrigation Department, and data collected from field measurements of canal discharge and seepage loss were used in the study. Irrigation requirement of the canal command area was worked out using the FAO’s CROPWAT 8.0 software. The results revealed that the average annual irrigation demand of the CRDS command area is 46.90 Mm3. Measured flow rate through the canal system showed that the flow decreases towards the tail end. Loss of water through seepage from the canal was high in the irrigation scheme due to the highly damaged condition of canal lining and poor maintenance. The CRDS canal system’s overall conveyance efficiency was found to be 51%. Based on Relative Water Supply and Adequacy Indicator, functioning of the irrigation scheme falls in the category of ‘fair’. Apart from proper repair and maintenance of canal system, conjunctive use of groundwater and canal water for irrigation is suggested towards the tail reaches to alleviate irrigation water inadequacy problems in the CRDS command area.

Analysis of Trends and Teleconnections between Streamflow and Climatic Drivers in Chalakudy River Basin

Analysis of Trends and Teleconnections between Streamflow and Climatic Drivers in Chalakudy River Basin

Farmer Resilience to Floods - A Post-Disaster Analysis in the Flood Plains of Kerala, India

Extreme weather and climate events lead to substantial economic impacts, loss of lives and livelihoods, and adverse effects on human well-being and the environment. In a scenario where intensity and incidence of climate change induced extreme weather events are common, disasters will continue to be a regular phenomenon, compelling us to learn to live with it. The resilience of rural communities to weather adversities need to be explored, to cope with, adapt to disasters. In the background of the unprecedented deluge that engulfed in Kerala, the southernmost tip of India, in 2018 the study was undertaken to analyse the resilience level of the affected farmers. Although people of the state have experienced minor floods in past years, the flood of 2018 left the people of the state wholly devastated, with the turbulent water taking away most of their assets and livelihood options. The study used the factor analysis and logit model to analyse farmer resilience. The study was conducted by selecting 120 sample farmers along the flood plains of Chalakudy river, one of the worst affected flood plains. Through factor analysis, seven factors representing eight components of resilience were identified. The analysis identified risk orientation as the highly influencing factor in building resilience. Logistic regression analysis revealed education and subsidiary occupation as having a positive influence, while family size and crop diversification index negatively influence resilience.

Flood Plain Mapping and Identification of Warning Level Prior to Flood for Chalakudy River

Abstract: Flood is one of the most dangerous disasters occur in the world. It endangers the lives of humans and other species. In India one – fifth of the global death rate is happening due to flood. From 2018 June 1 st to August 19 Kerala also experienced a high intense rainfall which results severe flooding. Five million people were affected and 433 people loss their life during this flood. Hence one way to minimize the effect of flood is proper operation of flood forecasting and flood control systems. In this paper we analysed drastic flood situations in Chalakudy river basin during the years 2018 - 2021. Mapping of flood plain of Chalakudy river basin was prepared using HEC – RAS and ARC GIS and initially drowned areas were mapped using Google Earth Engine. Also identified the flood warning level of Chalakudy river and each local bodies based on actual data and field surveys.

Length–weight relations of 14 fish species (Actinopterygii) from the Chalakudy River, Western Ghats, India

Length–weight relations of 14 fish species caught by small-scale fishery from the Chalakudy River of the Western Ghats biodiversity hotspot, India were analyzed from April 2018 to March 2019. The following species were studied: Amblypharyngodon microlepis (Bleeker, 1853); Dawkinsia filamentosa (Valenciennes, 1844); Puntius mahecola (Valenciennes, 1844); Osteobrama bakeri (Day, 1873); Labeo dussumieri (Valenciennes, 1842); Channa marulius (Hamilton, 1822); Channa striata (Bloch, 1793); Horabagrus brachysoma (Günther, 1864); Mystus armatus (Day, 1865); Pangasianodon hypophthalmus (Sauvage, 1878); Heteropneustes fossilis (Bloch, 1794); Etroplus suratensis (Bloch, 1790); Megalops cyprinoides (Broussonet, 1782); Parambassis thomassi (Day, 1870). The main fishing gear that was used in the data collection were gill nets, seine nets, and cast nets. The b values in the LWRs ranged from 2.649 (L. dussumieri) to 3.023 (P. hypophthalmus). This study reports the first LWR reference for five species and new maximum total lengths for five species. The results provide baseline information for the sustainable management and conservation of the studied species.

Length–weight relations of 14 fish species (Actinopterygii) from the Chalakudy River, Western Ghats, India

Length–weight relations of 14 fish species caught by small-scale fishery from the Chalakudy River of the Western Ghats biodiversity hotspot, India were analyzed from April 2018 to March 2019. The following species were studied: Amblypharyngodon microlepis (Bleeker, 1853); Dawkinsia filamentosa (Valenciennes, 1844); Puntius mahecola (Valenciennes, 1844); Osteobrama bakeri (Day, 1873); Labeo dussumieri (Valenciennes, 1842); Channa marulius (Hamilton, 1822); Channa striata (Bloch, 1793); Horabagrus brachysoma (Günther, 1864); Mystus armatus (Day, 1865); Pangasianodon hypophthalmus (Sauvage, 1878); Heteropneustes fossilis (Bloch, 1794); Etroplus suratensis (Bloch, 1790); Megalops cyprinoides (Broussonet, 1782); Parambassis thomassi (Day, 1870). The main fishing gear that was used in the data collection were gill nets, seine nets, and cast nets. The b values in the LWRs ranged from 2.649 (L. dussumieri) to 3.023 (P. hypophthalmus). This study reports the first LWR reference for five species and new maximum total lengths for five species. The results provide baseline information for the sustainable management and conservation of the studied species.

On the diversity and abundance of riparian odonate fauna (Insecta) of the midstream Chalakkudy River, Kerala, India

The riparian Odonate insect diversity of the midstream Chalakudy River at six locations assessed from February 2018 to January 2019 has revealed the occurrence of 25 species of odonates. Among them,10 species are dragonflies belonging to seven genera of the family Libellulidae and the remaining 15 species are damselflies belonging to six families and 11 genera. Five endemic damselfly species have been recorded. Pseudagrion indicum is endemic to the Western Ghats, while the remaining four species, Vestalis apicalis, Libellago indica, Dysphaea ethela, and Heliocypha bisignata, are endemic to India. Diversity indices of the odonates in all the six locations were analyzed and it showed less abundance at sites where tourist activities are more and with thin native riparian vegetation. Further, the study has unequivocally revealed that thick native riparian vegetation is essential for their perching and existence. By and large, the uncontrolled tourism activities and habitat alteration interfere with the density and diversity of these endemic species.

Calibration and Validation of HEC-HMS Model for Chalakudy River Basin

Prediction of flood prone areas in a basin and evolution of the impact of climate change on water resources needs a correct estimation of the availability of water which will solely be achieved by hydrological modelling of the basin. However, modelling the hydrology of a basin is a complex task and models should be well calibrated to increase user confidence in its predictive ability which in turn makes the application of the model effective. In this study rainfall-runoff simulation model viz., Hydrologic Modelling System, developed by the Hydrologic Engineering Centre USA (HEC-HMS) has been calibrated and validated for Chalakduy river basin in Kerala, in Sothern India for prediction of its hydrologic response. The result shows Curve Number (CN), Lag time and initial abstraction (Ia) to be the sensitive parameters for the simulated stream flow. The statistical analysis of Nash-Sutcliffe model efficiency criteria, the percentage error in peak, percentage error in volume, and net difference of observed and simulated time to peak, which were used for performance evaluation, have been found to range from (0.70 to 0.87), (4.39 to 19.47%), (1.9 to 19%) and (0 to 1day) respectively, indicating a very good performance of the model for simulation of stream flow.

Impact of urbanization on flooding in chalakudy river

Extreme events like floods are a concern for any country in terms of the damages caused to life as well as property. The recent trend of unpredictable rainfall in India leads to significant changes in the flow of the river and basin characteristics, which contribute to the aggravation of floods. In the cataclysmic flood in the year 2018 in Kerala, the Chalakudy river basin was completely inundated. This region has undergone extensive environmental changes since the 1990s due to agricultural expansion, deforestation, increased urbanization etc. These indicate the need for conducting a hydrologic and land use/land cover (LULC) change analysis to identify the causes, effects and solutions to mitigate the devastating effect of floods. This goal is achieved with the help of Geographic Information System (ArcGIS) and a hydrological model (HEC-HMS). The results from the study shows that tremendous change in land use pattern has occurred over the past few decades and the notable among them is the 1003.9% increase in built-up area. The increase in flood peak of the devastating Kerala Flood 2018, exclusively due to this land use change/urbanization is found to be about 22% in this study area.

Assessment of river water quality indices based on various fuzzy models and arithmetic indexing method

River water is a major source of natural freshwater for both rural and urban areas. The severe threat in the form of pollutants is the major cause of deterioration of surface water quality. Water Quality Index (WQI) is a single measure of overall water quality in a specific location with a special emphasis on the time-based readings of water quality parameters. WQI can be used as a good tool to assess the intensity of water pollution. In this study, two water quality index models using fuzzy logic in MATLAB R2015a by trapezoidal and sigmoid membership functions are proposed. Fuzzy water quality index models were developed for various seasons, using eight experimentally estimated water quality parameters, such as Temperature (T), Chlorides (Cal−), Nitrates (NO3 −), Sulphates (SO4 −), Total Coli forms (TC), Total Dissolved Solids(TDS), Electrical conductivity (EC) and Total Hardness (TH) of the water samples at 8 locations stretching55 km of Chalakudy River from January 2018 to December 2018. The models are validated by comparing with the WQI values obtained by the application of arithmetic index method (AIM) based on Indian Standards, by finding the absolute average relative error (AARE) and root mean square error (RMSE). The fuzzy logic model using trapezoidal membership function (FTWQI) was found to be more reliable with the least error (AARE 0.0214 and RMSE 0.318) compared with the fFuzzy sigmoid water quality index (FSWQI) (AARE 0.573 and RMSE 0.86). The models enable the easy prediction of the risk of water consumption.

Feeding ecology of the endemic freshwater puffer fish Carinotetradon travancoricus (Hora & Nair, 1941) in Western Ghats hotspot, India

The study aimed to investigate the feeding ecology of a vulnerable freshwater puffer fish, Carinotetradon travancoricus from the Chalakudy river of Kerala, Western Ghats, a biodiversity hotspot of India. Fishes were sampled from October 2018 to September 2019. Stomach condition of the fishes showed the percentage of empty gut to be significantly higher during all seasons ( P < 0.01). Feeding intensity depicted the fish to follow an ‘active’ feeding strategy (31.59±10.32%) during pre-monsoon season. Diet composition and relative length of gut analysis indicated that the fish during its early stages relied on an omnivorous diet however preferring autochthonous food materials such as insects (27.91%) and crustaceans (25.30%) during its adult stages. A perceptible variation in the feeding strategy associated with the spawning season of C. travancoricus was also noticed. During their spawning season (May-August), a greater preponderance towards animal matter (52.18%) was noticed in their diet. The results of gastrosomatic index indicated that feeding activity of C. travancoricus is considerably reduced (2.99) during the spawning period. The present study provides the baseline information on the feeding ecology of C. travancoricus which could be helpful to aquarists for breeding and rearing of this species in captivity and thereby reducing their fishing pressure in wild.

Environmental impact of quarrying of building stones and laterite blocks: a comparative study of two river basins in Southern Western Ghats, India

Mining and quarrying for minor minerals impart significant economic, environmental and social impacts in and around the affected areas. The problem is severe in the small river catchments as the effective area available for assimilating negative impacts of the activity is minimal, compared to large river basins. To address these issues, an investigation has been carried out in two river basins of southern Western Ghats (India)—the Netravati–Gurpur and Periyar–Chalakudy river basins. Both these basins host two important port cities of south India—Kochi and Mangalore. The study reveals that about 6.75 × 106 ty−1 of hard rocks are being extracted in the Netravati–Gurpur basin through 64 quarries. At the same time, the total number of quarries and extracted amounts in the Periyar–Chalakudy river basin are 525 and 10.47 × 106 ty−1, respectively. Many hillocks in the region are turned to a cluster of ugly scars, degrading the ecology and aesthetics of the area. Lowering of water table, modification or disappearance of natural drainages and environmental pollution are some of the other observations noticed in the area. The environmental impacts of laterite quarrying are comparatively less than that of rock quarrying as removal of the hard laterite cap rock enhances water percolation and makes the area more irrigable for agriculture. The study stresses the need for environment-friendly quarrying alternatives with stringent guidelines to improve the overall environmental quality of the area on one hand and to meet the developmental requirements on the other.

Length Weight Relationship and Relative Condition Factor Study in Sahyadria chalakkudiensis Inhabiting Western Ghat River Systems of South India

A trend on unethical and unsustainable use of resources to meet the high demand in the trade of indigenous ornamental fishes is widespread. This increased exploitation calls for regulation. Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), an apex body having a central role in regulating the trade of any living organisms including indigenous ornamental fishes and preventing the species from being left as extinct. To enlist a species in trade by CITES, formulation of baseline data on its biology, population size, length-weight relations, condition factor, and habitat ecology are necessary. This paper looks into one such consideration on Sahyadria chalakkudiensis inhabiting Western Ghat rivers of Kerala. The length-weight relationships in respect of males and females inhabiting Chalakudy river are expressed as Log W = -3.800 + 2.43 Log L and Log W = -4.333 + 2.69 Log L while the same in males and females inhabiting Pooyamkutty river are Log W = -4.545 + 2.76 Log L and Log W = -5.290 + 3.12 Log L respectively .There is a regular seasonal cycle in relative condition factor with a peak in August (Kn=1.33; Chalakudy population) and September (Kn = 1.15; Pooyamkutty population).The results indicated that management of stock of S. chalakkudiensis is very essential to ensure sustainability of its trade.