Kali Gandaki Research Articles

Length-weight relationship and exploitation of Macrobrachium species in the Burhi Gandak River, North Bihar, India

Three species of the Palaemonidae family, namely Macrobrachium dayanum (Henderson, 1893), Macrobrachium lamarrei (Milne Edw., 1837) and Macrobrachium malcolmsonii (H. Milne Edw., 1844) were investigated for their length-weight relationship and exploitation status in the Burhi Gandak River between July 2020 and June 2021. A total of 907 specimensof M. lamarrei, 942 M. dayanum and 962 M. malcolmsonii were collected using trap net (locally named Ghana Jal), Saalbhar Jal, Pelni, Dhonijal and Khorjal and traditional boats such as Nauka and Donga. M. lamarrei was found to be the dominant species among them in the catch composition. Peak landing was observed from June to August. The maximum length was recorded for M. malcolmsonii (16.8 cm) followed by M. dayanum (8.0 cm) and M. lamarrei (6.1 cm). The length-weight relationship of M. lamarrei, M. dayanum and M. malcolmsonii indicated negative allometric growth with slope (b) values of 2.7692, 2.6027 and 2.7513, respectively. The von Bertalanffy growth parameters viz., asymptotic length (L∞), growth coefficient (K) and age at zero length (to) were 5.67 cm, 2.3 y-1 and -0.5913 y-1 for M. lamarrei ; 10.08 cm, 0.990 y-1 and 0.6684 y-1 for M. dayanum and 16.59 cm, 0.730 y-1and -0.7289 y-1 for M. malcolmsonii , respectively. Fishing mortality was lower than natural mortality which was estimated as 1.71 for M. lamarrei, 0.15 for M. dayanum and 0.18 for M. malcolmsonii. The present study revealed that the smaller length groups had higher natural mortality, whereas larger length groups had higher fishing mortality. The current exploitation rate was 0.26 for M. lamarrei, 0.06 for M. dayanum and 0.09 for M. malcolmsonii. The research fills a critical gap providing essential insights into the population dynamics and exploitation of the three prawn species in the Burhi Gandak River, revealing their underexploited status, highlighting opportunities for sustainable harvesting and informed fishery management to support biodiversity conservation and local livelihoods. Keywords: Bihar, Burhi Gandak River, Length-weight relationship, Macrobrachium, Stock assessment

A Farmer-Centric Cost–Benefit Analysis of Climate-Smart Agriculture in the Gandaki River Basin of Nepal

Climate-smart agriculture (CSA) is a climate-resilient practice that stands out globally as an important practice through which we can deal with emerging challenges through adaptation and mitigation to increase crop productivity and resilience. Despite its significance, a comprehensive cost–benefit analysis of the adoption of these practices has not yet been carried out. This study aims to bridge the knowledge gap between the cost and effectiveness of CSA practices adopted by small-scale farmers in growing rice, wheat and maize, the most staple crops in the Gandaki River Basin of Nepal. In this study, net present value (NPV), internal rate of return (IRR), benefit–cost (BC) ratio, net benefit investment (NK) ratio and payback period, along with the value of externalities (social and environmental), were employed to assess the profitability of CSA practices. The findings indicate that almost all the CSA practices analyzed were profitable, with the exception of solar water management in maize with very low IRR (6%) and a longer payback period. The outcome of this study offers valuable insights for farmers in choosing profitable CSA technology and for policy makers in promoting better CSA technology, upscaling CSA practices, and formulating new agricultural policies and programs in the context of the changing climate.

Geomorphological characteristics of Gandak river between Sahibganj and confluence with Ganga river during 1989–2022

The Gandak River originates in Nepal and merges with the Ganga River in India. The Gandak River is experiencing significant geomorphological alterations due to climate change and anthropogenic causes. In this study, an attempt has done to examine river bank erosion & accretion, shifting of the river bank, sinuosity, and braiding index of the Gandak River between Sahibganj and the confluence with the Ganga River, covering a length of 92.4 km from 1989 to 2022 (33 years) using remote sensing and geospatial technologies. The delineation of the river bank line for different periods, along with the quantification of erosion and accretion of the river’s right and left banks, were analysed using GIS, including the sinuosity and braiding patterns. The overall sinuosity value ranged from 1.16 to 1.01 and did not follow any specific pattern in significant reaches. The sinuosity value was almost constant over the most d/s reach of 30.74 km. The braiding index of the River was found to be the maximum between Ismailpur and Baijalpur and the minimum value between Munja and Chakia in 2015 and 1995 respectively. This study revealed that the river is shifting to the right, and bank protection measures were needed. Finally, the proposed investigation revealed the braiding phenomenon, river shifting in the transverse direction, and shifting of the meander bend was primarily responsible for the erosion and accretion of the river banks. This study will benefit local government agencies, concerned authorities, and people residing along the banks of the Gandak River by providing insights into the river’s migration patterns. Further, this knowledge aids in better planning of riverbank protection measures and developing a navigation system.

Comparative Analysis of wear on Hard and Soft Coated Francis Runners: A Case study of Kali Gandaki ‘A’ Hydro Power Station

Abstract Surface coating on Turbine components is a regular practice in hydro power plants to tackle with wear. The Kali Gandaki ‘A’ hydro power station of Nepal having 3x48 MW Francis Turbine units made of CN 13/4 material has been regularly coating its Runners entirely using Tungsten Carbide based alloy through HP-HVOF hard coating process. In 2021 for the first time one of the Runners was partially coated around the blades using elastomeric semi-soft coating material manually via brush application, while the remaining portion of the Runner was hard coated. This study was conducted to compare the wear on the hard and soft coated runners after a similar period of operation under similar circumstances. Both the Runners were found to be heavily worn out at the upper and lower wearing rings, suction side of all blade inlets at the shroud and all blade outlets. The soft coated runner was found to have more erosion and cavitation wear than the hard coated runner. A unique canal-type cavity was found on the hub side wearing ring of the soft coated runner but no such pattern was seen on the hard coated Runner. The sections of the soft coated Runner where the coating was still intact had the parent material fully protected, but the sections with coating completely washed away were found to have deeper and wider cavities showing that the parent material had significantly washed away. The major reason behind the soft coated Runner being more worn out could be the manual application of coating material using hand brush which could have resulted in blade profile being distorted due to which the Runner efficiency might have reduced and thus higher erosion and cavitation occurred. This study could be useful to assess the applicability as well as the benefits and drawbacks of hard and soft coating on Francis Runner.

Possibilities of Ecotourism Development in Rani Mahal Area, Palpa, Western Nepal

Nepal has significant potential for tourism due to its diverse flora and fauna, rich culture, and abundance of mountains, historical sites, and religious places. This study assesses the potential for ecotourism development in the Rani Mahal area of Palpa district. The research was based on Focus Group Discussions (FGDs), Key Informant Interviews (KIIs), and field observations. In total, FGDs were conducted in five locations, and 38 KIIs were carried out. The study found that ecotourism activities such as white-water rafting, beach volleyball, homestays, and hiking are feasible in the Rani Mahal area. White-water rafting in the Kali Gandaki River (from Ridi to Ramdi) and beach volleyball in the Rani Mahal area were identified as highly promising for ecotourism. Similarly, homestays in Bote village (Dailathun) and Satuka (Syangja) were also found to have high potential. Additionally, hiking routes from Rani Mahal to Magar homestay (Baugha Gumha), Alamdevi temple (Syangja), Argali, and Ridi offer great potential for ecotourism activities. The results of this study provide valuable insights into tourism planning, infrastructure development, and the sustainable development of ecotourism in the Rani Mahal area.

Monkey menace in Nepal: An analysis and proposed solutions

Monkey menace is a prevalent issue in South Asia and Southeast Asia, where Rhesus macaques are considered pests of major field crops. In Nepal, factors such as monoculture cropping patterns, forest fragmentation, degradation of natural habitats, and changing agricultural practices contribute to increased monkey menace and human-macaque conflict. Factors such as cropping season, food resource distribution, crop variety, wild food availability, and distance from forests and farms influence the frequency and intensity of crop raiding. This study introduced non-human primates, their status, and availability in Nepal, and analyzed different crops raided by monkeys along the Buddhi Gandaki River, frequency and crop raiding season of monkeys in Jhor Mahankal and Goldhunga and suggested some solution measures for the monkey menace in Nepal. Maize was the most raided crop, while pumpkin was the least. The total percentage of crops raided was 24.62%, with an average crop loss of 29.24%. Crop raiding was most prevalent during the spring season (45%), followed by the rainy season (39%), and least prevalent during the winter season (16%). Rhesus macaques refrained from raiding crops with bitter or spicy flavors, such as turmeric, bitter gourd, chili, ginger, and mustard. The suggested control measures need to be followed to mitigate the monkey menace and manage the human-wildlife conflict.

Climate Change and Flood Vulnerability Analysis in the Narayani River of Nepal

Flood disasters annually devastate livelihoods, particularly during the monsoon season, with no apparent reduction in impacts in low-lying regions of developing countries like Nepal. Given the increasing effects of climate change globally, this study aims to assess climate change effects and biophysical vulnerability of riverine communities to floods in the Narayani River of Nepal, elucidating the interrelationship between these phenomena. This paper presents an analysis of trends and extreme events of climatological variables, such as temperature, precipitation, and daily river discharge and hazard mapping and risk assessments in the river stretch of two Village Development Committees (VDCs) in the country’s inner Terai region of Nawalparasi district for different return-period floods, with the aid of the HEC-RAS (Hydrologic Engineering Centre’s River Analysis System) and HEC-GeoRAS. A long-term climatological data was collected from the Department of Hydrology and Meteorology, Kathmandu, and the analysis was performed using statistical softwares, SigmaStat, and SigmaPlot. In addition, flood conditions representing 2, and 100-year periods were determined using Gumbel’s distribution. The study revealed a narrowing temperature range, with increasing minimum temperatures and decreasing maximum temperatures, precipitation, and river discharge. However, there was a notable increase in extreme events. The hazard mapping indicated the people’s vulnerability to inundation and soil erosion along the low-lying riverbanks. The findings underscore the necessity for reliable technological and socio-economic vulnerability mapping to provide early warnings to at-risk populations. This paper argues that unplanned and mismanaged settlements in riverine areas may lead to population displacements, creating environmental refugees.

Uncertainty estimation of hydrological modelling using gridded precipitation as model inputs in the Gandaki River Basin

Study RegionFour subbasins in the Gandaki River Basin in the southern Himalayan region. Study FocusIn the southern Himalayan region, gridded precipitation datasets are often used to complement sparse gauge network observations in hydrological modelling for water resource assessment. However, the applicability and uncertainty of using these datasets in hydrological modelling remain to be evaluated. In this study, nine high spatial resolution gridded precipitation datasets were used to force a widely used hydrological model to simulate the daily runoff at four hydrological stations in this region. The accuracy of these datasets was evaluated, and the model calibration results and modelling uncertainty were analyzed. New Hydrological Insights for the RegionOur analysis revealed large differences among the nine gridded precipitation datasets, and most datasets underestimated the annual precipitation in the low-elevation regions and overestimated that in the high Himalayas. Furthermore, through the adjustments of model parameters, the underestimations of precipitation by gridded datasets were compensated for by the overestimation of glacial melt. Therefore, the model performance was better, and the model uncertainty was lower in basins with higher glacial coverage. Notably, our findings indicated that the performances of gridded precipitation datasets were heterogeneous and that their direct use in hydrological modelling may result in unreasonable hydrological process variables; thus, these datasets should be evaluated and used with caution in water resource assessments in Himalayan regions.

Impact of climatic changes on fish biodiversity and their conservation (India)

India, having numerous rivers, is enriched with varieties of flora and fauna in and around it. The total catchment area of the river basin is about 2.5 lakh km2 or 81% of the total geographical area of India. All over India, there are remarkably diverse ranges of aquatic life. 950 freshwater and 1570 marine fish species, a total of 2500, are found which occupies 1.5% of the world's total fish species. Fish is full of nutrition and a prime source of aquatic food. But in this fast-developing urbanization era: anthropogenic activities, industrialization, population, elevated air temperature, global warming, drought, flood, pollution, and monsoonal ups and downs equally put pressure on the climate, ecosystem, society, and economy, increasing pressure on all livelihoods and food supplies, including those in the fisheries and aquaculture sector. The actual properties of climates are being changed very rapidly. Fish availability in the monsoonal season is more than in the summer season. Therefore, the present study aims to determine the present status of fish biodiversity of river Gandak and the significant role of climate change on them. The study was conducted from January 2022 to August 2022 in Gandak river. Overall, 25 individuals of fishes were recorded and characterized which belonging to 12 families, Cyprinidae (32%) was most abundant, followed by Channidae (12%), then Bagridae, Siluridae, Cobitidae, Ambassidae with 8%; Notopteradae, Heteropneustidae, Claridae, Belontidae, Belonidae, Nandidae occupied only 4%. families. Aspidoporia morar and Puntius species, Labeo calbasu and Labeo bata were in good quality while Labeo rohita and Catla catla were not found in good amounts. A good number of ornamental fishes were also recorded. But after these surveys, it was seen that there was a significant decline in their population that also affect other depending organisms along with local fishermen directly or indirectly. So, the need of the hour is conservation which involves restoration of habitat, cleaning of rivers, sewage treated water, mass awareness program to people for water conservation, sustainable use of river water and its resources and these will help the fishermen in livelihood and earning along with the nutritional need of the society.

Carapace Length-weight, Carapace Width-weight Relationships, Condition Factor and Sex Ratio of Freshwater Crab Sartoriana spinigera (Wood-Mason, 1971) from the River Burhi Gandak, North Bihar, India

Background: The Burhi Gandak river origins in the Chautarwa Chaur region near Bisambharpur in the West Champaran district of Bihar and flows through the East Champaran, Muzafarpur, Samastipur and Begusarai districts. It falls into the river Ganga near Khagaria district. Its coordinates are 25°51'40''N latitudes and 85°48'36''E longitudes. The total area of catchment is 12500 sq. km in size overall, of which 9601 sq. km are in Bihar and the rest in Nepal. The study will be helpful for stock estimation, developing conservation and choosing appropriate species for aquaculture. The present data can be used to develop conservation plans while providing biological data needed for an effective management of this fishery. Methods: The carapace length-weight, carapace width-weight relationship, condition factor and sex ratio of freshwater crab Sartoriana spinigera (n=663) collected from River Burhi Gandak, North Bihar, between July 2020 to June 2021. In the present investigation, freshwater crabs were collected from different types of techniques, including hand-picking, digging, setting traps and taking them from their nest. Result: Total of 663 specimens of Sartoriana spinigera (Wood-Mason, 1971) of both sexes (male and female) were collected in which 363 female and 300 male. The carapace length-weight of Sartoriana spinigera females were calculated as W = 0.9122.521 with R2 = 0.875, male W = 0.43102.505 with R2 = 0.853 and length-weight of combined sex (male and female) were calculated as W = 0.6612.701 with R2 = 0.954. The carapace width-weight of female were calculated as W = 0.5542.331 with R2 = 0.831, male W = 0.7912.421 with R2 = 0.802 and carapace length-weight of combined sex (male and female) were calculated as W = 0.18122.601 with R2 = 0.900. From this study showed it could be stated that crabs have allometric growth pattern. The Fulton’s condition factor (Kn) value were calculated as 1.10 and sex ratio calculated was 1:1.49. This paper provides information.

Ecological Regeneration of Wetland: Case Study of Kanwar Lake, Begusarai

The wetlands are the partially water-submerged environments that are highly productive, and support fauna and flora species in significant numbers that are dependent for their survival on the organic production of wetlands. Kanwar Lake is situated about 22 kilometers to the northwest of Begusarai. The Gandak River, a tributary of the Ganges, meanders across the area, creating the largest oxbow lake in Asia. It is a natural body of water that is significant on many different levels, including ecological, floral, faunal, geomorphological, and zoological. In 1989, the state government of Bihar designated Kanwar as a protected area for avian species. It has been considered a Ramsar site since 1987, but the wetland was not one of the 13 designated sites. In 1984, the lake’s area was 6,786 hectares (ha), but by 2004, it had shrunk to 6,043.825 ha. Only 2,032 hectares remained of the original lake area by 2012. Wealthy farmers and locals have rapidly colonized the lake bed. Lake biodiversity has declined as weeds have grown across the wetland. Widespread deforestation, overgrazing, unsustainable agricultural methods and over-exploitation of biomass for wood, fodder, and timber have stripped the land of its natural vegetative cover and exacerbated erosion. The research deals with the ecological study of the area and how urbanization has caused impacts on it. It focuses on how this has caused the deterioration of the lake and the measures for restoring the lake ecology, safeguarding the trend of urbanization. After analyzing the major key issues and analyzing the issues at the edge of the lake and around the Manjhaul, some of the major findings conclude that there is a need for stormwater management of the whole city, restoration of Kanwar wetland, and industrial control around the lake.

Constraining the exhumation history of the Greater Himalayan Sequence, Kali Gandaki, Central Nepal

To understand the evolution of the Himalayan orogen, we first need to understand how the South Tibetan Detachment System (STDS) evolved through time and space. We present new (and previously published) thermochronological results from a transect in the footwall and ductile shear zone of the basal structure of the STDS in the Kali Gandaki region: the Annapurna detachment. The exhumation history is interpreted from observations using 1D thermal–kinematic models that invert to give the exhumation rate of samples. Recently published data have suggested that high-temperature slip on the detachment persisted until at least c. 12 Ma, more recently than is commonly assumed for STDS deformation. Our new data and modelling support these findings and suggest that the cessation of slip coincided with a dramatic (>50%) decrease in the exhumation rate of the shear zone and its footwall at c. 12–10 Ma. Exhumation rates remained low until c. 3 Ma, after which they increased to levels comparable with those that characterized STDS activity. Plausible causes of this late pulse of exhumation include an intensification of the Asian winter monsoon and the establishment of today's Indian summer monsoon, glaciation and/or an internal structural reorganization of the Himalayan orogenic wedge driving localized rock uplift in the hinterland. Supplementary Material, including method descriptions, full datasets and supplemental figures, is available at https://doi.org/10.6084/m9.figshare.c.6949467

Climate change impacts on Seti Gandaki River flow from hydropower perspectives, Nepal

Climate change impacts on Seti Gandaki River flow from hydropower perspectives, Nepal

Population changes in Gharial (Gavialis gangeticus) vary spatially in Chitwan National Park, Nepal

Gharials, large crocodilians found only in South Asia, are widely seen as a flagship species for river conservationin Nepal, especially in Chitwan National Park, where a headstart program has supplemented the populationsince 1981. The population has shown signs of recovery only in the last decade, so continued monitoring of populationtrends is vital for conservation. We conducted annual winter population surveys for gharial in Chitwan between 2017and 2022, during which we also characterized riverbank substrate availability and basking preferences. We documentedpotential threats to the species in Chitwan throughout the year. Overall, we counted an increasing number of Gharialsin Chitwan; however mixed-effects modelling of Gharial encounter rate showed that increasing encounters rates are notevenly distributed throughout available habitat, with some river stretches having stable or decreasing trends. Encounterrates on the Rapti River increased in all transects, compared to more variable results on the Narayani River, likelyattributable to higher levels of human disturbance and the impact of captivity on habitat selection. Fewer Gharials wereseen in transects with high levels of disturbance due to sand mining and the extraction of river substrates, highlightingthis threat as a major concern. Regular reports of bycatch in illegal gillnets was the major observed source of mortality.A lack of an increasing population trend in the stretch above a large barrage suggests that recruitment is minimal inthis area, and the dam likely has a negative impact on upstream Gharial recruitment. We cautiously suggest that theChitwan population is recovering, but that recovery is hampered by threats, especially substrate extraction, illegal gillnetfishing, and river fragmentation by a dam.

Multi-site calibration of the SWAT hydrological model and study of spatio-temporal variation of water balance components in the Narayani River Basin, central part of Nepal

Abstract Science-policy interaction is vital for addressing hydro-climatic disasters in data-limited regions, with modeling and analysis as key components. The utilization of the soil and water assessment tool (SWAT) model facilitated an evaluation of water balance variations across time and space within Narayani Basin through multi-site calibration. The adjustment of all parameters via the SUFI-2 algorithm revealed that precipitation and temperature lapse rate (PLAPS and TLAPS) exhibit higher sensitivity in scenarios where observed stations fail to capture orographic effects. The calibrated model accurately replicated evapotranspiration, net water yield, and groundwater flow for each sub-basin, including average flow and flow duration curve at calibration points. Findings indicated that 22% of precipitation is lost to evaporation, while 75% contributes to basin runoff, showcasing significant spatial and temporal variability in water balance components. Notably, net water yield comprises 44% lateral flow, 38% surface flow, and 16% groundwater flow, with distinct spatial patterns favoring lateral flow in the Himalayas and groundwater flow in the plains due to topographical variations. These outcomes offer actionable insights for policymakers and water resource managers, enabling assessments of climate and land use impacts and facilitating the formulation of policies for sustainable water resource utilization.

Assessment of the Effect of Climate Change on the Hydrology in Seti Gandaki River Basin: A Case Study of Seti Khola Hydropower Project

Assessment of the Effect of Climate Change on the Hydrology in Seti Gandaki River Basin: A Case Study of Seti Khola Hydropower Project

Effect of Coarse Aggregate Size Variation on Compressive Strength of Concrete along the Length of Kali Gandaki River

The Kali Gandaki River is renowned for its diverse geological composition, providing a unique opportunity to examine how the inherent characteristics of coarse aggregates impact concrete performance in terms of compressive strength. This research delved into the influence of varying coarse aggregate sizes on the compressive strength of concrete obtained from different points along the Kali Gandaki River. Multiple samples of coarse aggregates were gathered from distinct geological regions along the river. The study adopted a concrete mix design for M20, and concrete cubes were manufactured with coarse aggregate sizes ranging from 10mm-16mm, 16mm-20mm, 20mm-25mm, to 25mm-31.5mm. All sample sets underwent compressive strength testing after 7 and 28 days of curing. The results revealed that, under identical curing conditions and water-cement ratios, the compressive strength of the produced concrete increased with the aggregate size, reaching a peak at 25mm. Additionally, among the surveyed locations, namely Ramdi Ghat, Khada Ghat, Pakhichaur Hungi Ghat, and Belchaur Ghat, Belchaur Ghat exhibited superior performance in compressive strength. The findings of this work aim to contribute valuable insights to the field of concrete technology and construction industry.

Calcite fabric development in calc-mylonite during progressive shallowing of a shear zone: An example from the South Tibetan Detachment system (Kali Gandaki valley, Central Himalaya)

Calcite-rich lithologies within the Annapurna Detachment zone, a strand of the South Tibetan Detachment System in central Himalaya (Kali Gandaki region, Western Nepal) have been characterized for the superimposition of microstructures to unravel deformation variations during syn-collisional exhumation. Finite-strain, grain size, twinning and crystallographic preferred orientations have been combined to define the contribution of dynamic recrystallization and twinning in calcite in the overall deformation. Dynamic recrystallization and twinning occurred respectively at temperatures of c. 400–550 °C and <250 °C. The comparison of calcite-based paleopiezometers indicates that cooling occurred along with an increase in differential stress from c. 4–19 MPa up to c. 118–154 MPa at decreasing strain rates. Flow estimates with the subsimple shear (30–50% of simple shear) regime for both fabrics support a single progressive deformation where the plastic regime progressively changed. We interpret the changes in intracrystalline deformation mechanisms in calcite and their differences in differential stress records, deformation temperature, and strain rate as linked to the exhumation of the rocks induced by the detachment, from deeper to upper crustal levels. Results for the Annapurna Detachment zone have been compared with the literature database for the regional continuation along the Himalaya, the South Tibetan Detachment System, which is defined by a lower main shear zone and an upper brittle fault. Data comparison led us to link our early stage of ductile shearing to that elsewhere recorded in the main lower branch of the system. Conversely, data for the late shearing are not found for the main branch when affecting quartz-bearing rocks, as strain hardening resulted in an upward partitioning of the deformation and in the localization of a brittle fault. Therefore, this study highlights how variations in lithology in regional-scale shear zones influences the exhumation path and the overall architecture of shear zones.

Flood Hazard Mapping and Risk Assessment in Narayani River Basin, Nepal

Floods, earthquakes, forest fires, landslides, and other natural hazard are common in Nepal. Among them, the flood is one of the natural disasters and that occurred in the Narayani River basin. The Narayani River Basin's exposures and vulnerabilities are at danger from a flood catastrophe of this kind, hence this studies attempts to reduce and control the risk of flooding in order to better manage disasters. The factors of flood hazard, flood exposures, and flood vulnerability are investigated as part of the ward-level flood risk assessment, which aims to prevent and manage the flood disaster. The hydraulic model (HEC-RAS) for the 2018 flood event was used in this study to create the GIS- based modeling of the flood inundation maps. Additionally, it calculated the various return periods for floods in the river basin—5, 10, 25, 50, 75, and 100 years. Furthermore, the flood extent was confirmed using the flood map produced by the Google Earth Engine (GEE) using remotely sensed techniques. For Hydraulic modelling, ALOS/PALSAR Digital Elevation Model (12.5m.) spatial resolution was used. In addition, RAS-MAPPER generated the geometric data for the hydraulic modeling, which was then transferred into HEC-RAS. This data included the cross-section, flow route, streamline, and bank lines. On both sides of the river, the necessary Manning value "n" values were computed for every cross-section. The steady-flow models of the anticipated flood hydrographs were created using the hydraulic model. Google Earth Engine (GEE) flood maps generated from Sentinel-1C radar satellite data were used to validate the results for the 2018 flood events. When comparing the simulated result's flood inundation area with the remote sensing data's flood area, the overlap area for the 2018 flood event is 65%. Additionally, the flood area is verified. In addition, the hydraulic model generated flow conditions for 5, 10, 25, 50, 75, and 100 year return periods. The river basin's surface water level and flood extent are both progressively rising. In order to effectively manage and prepare for potential flood hazards in the study area, an analysis of the flood risk assessment was conducted by taking into consideration three primary factors: the flood hazard map, flood exposure, and flood vulnerability. The layers of the population, crops, schools, hospitals, and road network were all exposed to flooding, and the factors that determined flood vulnerabilities were literacy, urban area, and agecomposition (less than 14 and more than 65). The higher flood risk area was found in Ward number 1, 3, 4,16,18,26 of Bharatpur metropolitan, Gaindakot municipality ward number 1 and 12, 15 of Madhyabindu Municipality.

Analysis of Farmers’ Perceptions of Climate Changes and Adaptation Strategies in the Transboundary Gandaki River Basin

Global climate change poses many adverse impacts and risks, which affect the livelihoods of local farmers. This study has assessed farmers’ perceptions of climate changes and adaptation strategies in the transboundary Gandaki River Basin (GRB). A total of 639 households were surveyed purposively from different physiographic regions, ranging from the lowland plain to the high Mountain region of the GRB. These surveyed perceptions were analyzed using a binary logistic regression (BLR) model. The results show that the significant variables determining the climate change perceptions are family size (p = 0.004), total number of livestock owned by the household (p = 0.000), availability of irrigation facility (p = 0.000), temperature change (p = 0.007), precipitation change (p = 0.000), and household head’s age (p = 0.044), education level (p = 0.000), and profession (p = 0.003). The results were also analyzed by physiographic region. Farmers in the Mountain region perceived the household head’s education (p = 0.008) and profession (p = 0.009), precipitation change (p = 0.028), climate-induced disease/pests (p = 0.042), and impact on vegetation (p = 0.044) as significant variables. Significant variables in the Hill region were found to include the household head’s education (p = 0.029) and profession (p = 0.043), lack of irrigation facility (p = 0.029), precipitation change (p = 0.018), increased drought (p = 0.018), and decreased agricultural production (p = 0.025). Similarly, farmers in the Tarai region noticed the lack of irrigation facility (p = 0.011), temperature change (p = 0.042), precipitation change (p = 0.017), impact on stable crops (p = 0.043), and decreased agricultural production as important variables. Likewise, in the Gangetic Plain (GP) region, the household head’s education (p = 0.010), total number of livestock (p = 0.037), lack of irrigation facility (p = 0.006), precipitation change (p = 0.003), increased drought (p = 0.002), and decreased agricultural production (p = 0.001) were found to be significant variables. The determinant factors vary between the different regions due to the geography and overall socio-economic factors of the respondent. Combining the scientific data with the farmers’ perceptions may help to clarify how climate change affects the farmers’ perceptions and adaptation strategies to better enhance their livelihood.