Karnali River Research Articles

Grain size and sediment load control on channel migration patterns of the Ghaghara river from Faizabad to Deoria, Ganga plain, India

Grain size and sediment load control on channel migration patterns of the Ghaghara river from Faizabad to Deoria, Ganga plain, India

Human-Wildlife Conflict in Bardia-Banke Complex: Patterns of Human Fatalities and Injuries Caused by Large Mammals.

Human fatalities and injury from wildlife attacks often result in a negative attitude toward conservation. This research was undertaken to investigate the patterns and conflict-causing factors of human killing and injury by large mammals, especially by Asian elephant (Elephas maximus), common leopard (Panthera pardus), and Bengal tiger (Panthera tigris tigris) in the Bardia-Banke Complex of western Nepal. We collected human death and injury records caused by wildlife in the Bardia-Banke Complex between 2019 and 2023, based on relief applications submitted by the victim's family. Additionally, camera trap monitoring was conducted following incidents of human-tiger and human-leopard conflicts. A total of 76 incidents involving human casualties and injuries were considered for analysis. Incidents of livestock depredation, crop raiding, and property damage were excluded from the analysis. Most of the attacks on humans were caused by tigers (75%), followed by elephants (16%) and leopards (9%). Almost all incidents occurred in daytime (97%). The highest number of conflicts were recorded in 2021, with 20 incidents. Most of the cases (84%) occurred within 1 km of forest edge. Khata corridor and the western side of the Bardia National Park, i.e., Karnali River corridor, were identified as high-conflict areas. The primary causes of the conflict manifested in cattle grazing (28%), grass cutting (28%), firewood collection (11%), fishing (8%), vegetable collection (5%), sand collection (4%), during rescuing friends (3%), grazing captive elephants (3%), highway rides (3%), sleeping in Chaupadi Goth (3%), walking nearby forest areas (3%), playing nearby forest areas (1%), while feeding pig (1%), and working in agricultural lands (1%). To promote human-wildlife coexistence, community-based patrols (33%), habitat restoration (26%), electric fencing (26%), and insurance (7%) were identified as the preferred strategies. Therefore, we recommend that stakeholders and concerned bodies increase awareness among local community about the use of forest resources, wildlife behavior, and human-wildlife conflict mitigation strategies.

Quantitative Assessment of Channel Migration in the Ghaghara River, Ganga Plain, India

ABSTRACT The Ghaghara River is one of the longest tributary of the Ganga River. The Ghaghara, a snow fed river is well known for channel shifting/migration. It was analyzed for lateral migration using multi-temporal satellite images and SOI toposheets. It shows 4.2 to 6.1 km lateral migration in last 45 years (1975–2020) between Bahraich and Deoria in the state of Uttar Pradesh. The lateral migration on the left side of the river (NNE) is 6144, 4838, 6475 and 4755 m, whereas on the right side (SSW) is 7021, 4555, 4718 and 4257 m during 1975–1990, 1975–2000, 1975–2010 and 1975–2020, respectively. The rate of migration (m/year) on left side (NNE) is 410, 194, 185 and 106, whereas on the right side (SSW) is 468, 182, 135 and 95 during 1975–1990, 1975–2000, 1975–2010 and 1975–2020, respectively. The major factors such as heavy precipitation, reactivation of chute channels, deposition of sediments, breaching of embankments and sand mining etc. might be responsible for the lateral migration of the river. Human settlements should be constructed away from the migration-prone area and regular monitoring and management system needs to be in place to mitigate the impacts of such natural events.

Understanding arsenic and manganese enrichment in the aquifers of the Ghaghara river basin, Middle Gangetic Plain (MGP), India: A multivariate statistical, compositional data analysis (CoDA), and receptor model approach

The focus of this study was to comprehend the spatial distribution, source apportionment, evaluation of natural background level (NBL), and mobilization mechanisms of arsenic (As) and manganese (Mn) in the Ghaghara river basin, located in the middle Gangetic plain (MGP) of India. A combination of analytical tools was employed, including multivariate statistical analysis (MSA), correlation analysis, and receptor models such as positive matrix factorization (PMF) and principal component analysis-multi linear regression (PCA-MLR). Taking into consideration the compositional constraints of the geochemical data, compositional data analysis (CoDA) methods were applied on the raw data prior to the correlation analysis and MSA. The results of MSA, correlation analysis and receptor models showed that major ion chemistry and As, Mn enrichment in groundwater were largely controlled by carbonate weathering, Fe and Mn oxyhydroxides dissolution. Anthropogenic activities, such as the infiltration of dissolved organic matter-rich water from local surface water bodies used as dumping sites and the infiltration of fertilizer-rich water from agricultural lands, were found to notably impact the groundwater geochemistry and release of As in the research area. The lower NBL of As (5.92 μg/L) compared to its mean concentrations (17.9 μg/L) in the study area also indicated that the rate of As release in groundwater through natural processes was comparatively low but various anthropogenic activities operating in the study region possibly acted as a trigger for the mobility of As from the mineral phases of the subsurface sediments. This study also highlighted the significance of applying CoDA techniques on geochemical data prior to statistical analysis, and the importance of receptor models, to better understand the nature and contribution of various natural and anthropogenic processes governing the hydrochemistry of groundwater in the alluvial aquifers.

Investigating the Parasitic Diversity of Nile Tilapia in the Ghaghara River: A Study on Fish Health and Monogenean Parasites.

This study investigates the presence and diversity of monogenean parasites infecting Nile tilapia (Oreochromis niloticus) in the Ghaghara River, recognizing their significant impact on fish health. Through field surveys, Nile tilapia specimens were collected from various locations along the river and subjected to standard parasitological analyses to identify monogenean parasites. Morphological assessments facilitated species identification and diversity assessments. Preliminary findings reveal a diverse array of monogeneans infecting Nile tilapia in the Ghaghara River, with species richness and prevalence varying across sampling sites, possibly influenced by environmental factors. While some monogenean species exhibit host-specificity, others demonstrate a broader host range. Understanding the distribution and diversity of these parasites would enhance our understanding of fish health and Ghaghara River ecosystem dynamics, informing management strategies for sustaining robust fish populations and promoting eco-friendly aquaculture practices in the region. Moreover, insights gained from this research may contribute to the conservation and management of aquatic ecosystems beyond the Ghaghara River.

Assessing Climate Change Impacts on Streamflow and Baseflow in the Karnali River Basin, Nepal: A CMIP6 Multi-Model Ensemble Approach Using SWAT and Web-Based Hydrograph Analysis Tool

Our study aims to understand how the hydrological cycle is affected by climate change in river basins. This study focused on the Karnali River Basin (KRB) to examine the impact of extreme weather events like floods and heat waves on water security and sustainable environmental management. Our research incorporates precipitation and temperature projections from ten Global Circulation Models (GCMs) under the Coupled Model Intercomparison Project Phase 6 (CMIP6). We applied thirteen statistical bias correction methods for precipitation and nine for temperatures to make future precipitation and temperature trend projections. The research study also utilized the Soil and Water Assessment Tool (SWAT) model at multi-sites to estimate future streamflow under the Shared Socioeconomic Pathway (SSP) scenarios of SSP245 and SSP585. Additionally, the Web-based Hydrograph Analysis Tool (WHAT) was used to distinguish between baseflow and streamflow. Our findings, based on the Multi-Model Ensemble (MME), indicate that precipitation will increase by 7.79–16.25% under SSP245 (9.43–27.47% under SSP585) and maximum temperatures will rise at rates of 0.018, 0.048, and 0.064 °C/yr under SSP245 (0.022, 0.066, and 0.119 °C/yr under SSP585). We also anticipate that minimum temperatures will increase at rates of 0.049, 0.08, and 0.97 °C/yr under SSP245 (0.057, 0.115, and 0.187 °C/yr under SSP585) for near, mid, and far future periods, respectively. Our research predicts an increase in river discharge in the KRB by 27.12% to 54.88% under SSP245 and 45.4% to 93.3% under SSP585 in different future periods. Our finding also showed that the expected minimum monthly baseflow in future periods will occur earlier than in the historical period. Our study emphasizes the need for sustainable and adaptive management strategies to address the effects of climate change on water security in the KRB. By providing detailed insights into future hydrological conditions, this research serves as a critical resource for policymakers and stakeholders, facilitating informed decision-making for the sustainable management of water resources in the face of climate change.

Length-Weight Relationship and Condition Factor of a Commercial Food Fish Labeo rohita (Hamilton, 1822) from Ghaghara River, Uttar Pradesh, India

The present study provides first-hand information about the length-weight relation of Labeo rohita (Hamilton) from Ghaghara River, Uttar Pradesh. We collected 107 specimens and took length and weight for better conservation techniques and proper management for rohu. A total of 107 specimens were examined for the study, which has ranging from 25.2-56.13 cm TL (Total length) and 183.3-2409.78 gm (weight) were used for the study of LWRs and condition factors. Our study represented that L. rohita exhibited a negative allometric growth (b < 3) indicating that the fish grows faster in length compared to their weight. The values of the correlation coefficient (r2) and condition factor (K) are 0.8601 and 1.27 respectively. This research will be useful for fishery research, stock assessment, conservation, and estimation of the fish condition of this Himalayan River.

Impact of Irrigation Dams on Fish Diversity of Budhikhola in Bardiya, Lumbini Province of Nepal

This extensive study describes the current status of freshwater fish diversity in the Budhikhola which is an important branch of the Karnali River that runs through the western region of the Bardiya district covering about 30 km distance in the north-south direction. To examine the effects of irrigation dams on habitat modification and fish variety, fish were collected from the entire Budhikhola stretch, with four sampling stations established depending on habitat structure. The freshwater system of the Budhikhola harbors a diverse and ecologically complex fish community comprising 41 species from 6 orders and 13 families. The dominance of the Cyprinidae family, represented by Barilius barna, Chanda nama, Chagunius chagunio, etc., highlights its ecological significance. On the other hand, the loss of important fish species is proof that the building of irrigation dams has had significant ecological effects. Human-induced hazards such as damming and overexploitation, have adversely impacted the river environment, resulting in reduced water depth, habitat structure changes, and restricted nutrient flow. The majority of the riverbed had been observed to be silt-covered. Significant fish species loss indicates ecological instability brought on by human activity. Changes in the distribution of fish sizes and spatial differences between upstream and downstream areas highlight the complex link between habitat modifications and community functioning. The catch-per-hour seasonal tendency, which peaks in September and falls in March, is correlated with fishing patterns, environmental factors, or breeding seasons. The evenness value (0.96) and high Shannon-Weiner Diversity Index (H'= 3.57) show a diverse and harmonious fish community. The relevance of family-level distinctions in implementing effective conservation and management measures is highlighted by major differences among family groups (p<0.001). As the findings make clear, the long-term survival of the diversified fish ecosystem of the Budhikhola depends on addressing and reducing anthropogenic stressors. This study provides valuable insights for informed conservation efforts in the aquatic ecosystems of Nepal.

Status of the Critically Endangered gharial Gavialis gangeticus in the upper Ghaghara River, India, and its conservation in the Girwa–Ghaghara Rivers

AbstractThe gharial Gavialis gangeticus is a Critically Endangered crocodilian endemic to the Indian subcontinent. Habitat modification by river damming and water extraction has caused a severe decline in its population. The status of the gharial is known within protected areas, but there have been few surveys for this species in unprotected areas. In Katerniaghat Wildlife Sanctuary, a breeding gharial population in Girijapuri Barrage Reservoir has low recruitment, and it has been hypothesized that yearlings disperse downstream into the unprotected Ghaghara River when the barrage gates are opened. We surveyed a 100-km stretch of the Ghaghara River from the Girijapuri Barrage to Chahlari Ghat, observing a total of 84 gharials, including a high proportion of juveniles. A survey in 2021 from Chahlari Ghat to Ayodhya observed 174 gharials, giving a combined total of 258 gharials in a 219-km stretch of the Ghaghara River for the two surveys. Together, these findings confirm the presence of a significant population of gharials in the Ghaghara River. We recommend the adoption of an integrated approach, involving government agencies and local communities along the river, to conserve the protected Girwa–Kaudiyala Rivers and the unprotected Ghaghara River for gharial conservation and recovery. Such a programme will need to tackle the threats facing the gharial and establish baseline data and long-term monitoring protocols for freshwater species conservation in this river system.

Improving evaluation of groundwater heavy metal(loid)s pollution efficiencies: Insights from novel Shannon entropy-weight and one-way ANOVA analysis

This study explores the hydrogeochemical behaviour of heavy metal(loid)s [HMs] in groundwater, their seasonal variations in enrichment and depletion, and adverse effects on human health in the Bahraich district of Uttar Pradesh, a part of the Ghaghara River basin, India. The Shannon's Entropy-Weighted Heavy Metal(loid)s Index (EW-HMI), a novel tool, has been applied to quantify cumulative groundwater pollution levels at each 42 monitoring sites, including critical evaluation of existing conventional pollution indices. Results from One-way ANOVA analysis indicate a significant seasonal difference in the mean concentrations of As, Fe, and Mn, demonstrating that monsoonal recharge is a governing factor for observed seasonal variation. The computation of EW-HMI reveals that >50% of sites are marked by ‘poor’ to ‘extremely poor’ water quality in Pre-monsoon 2022 (Pre-M). Distinctly, there is a notable improvement in 'excellent water quality', increasing from 9.5 to 57.1% in Post-monsoon 2022 (Post-M). This pattern of temporal change in EW-HMI, in contrast to HPI, is clearly depicted by the GIS-based spatial distribution maps. Thus, EW-HMI is a robust index and more effectively addresses apparent flaws in conventional indexing systems that could be used for wider applications. Health risk assessments (HRA) show that both children and adults in the Bahraich district are at risk of non-carcinogenic (NCR) and carcinogenic (CR) health effects from drinking contaminated groundwater. Children are anticipated to have a higher total CR mean value of 3.6 and 1.7 per 1000 children while adults estimated to have relatively low total CR mean values of 2.3 and 1.1 per 1000 adults in Pre-M and Post-M, respectively. This research offers valuable findings that can guide policymakers and stakeholders in identifying priority areas to facilitate the implementation of sustainable water resource management initiatives on both national and global scales.

Impact of Flooding on Nutritional Status among Early Childhood Development

Purpose: The purpose of this study is to assess and compare child nourishment in the communities affected by flood and non-affected households based on perception. Design/Methodology/Approach: The data was collected from flood-affected and non-flood-affected areas of households using a structured questionnaire consisting of both closed-ended and open-ended questions, followed by a face-to-face interview with the mothers or caretakers of children ranging in age from 3–5 years. A case study was also conducted in an exceptional case for further validation to dig deeper. A judgmental sampling technique was used to identify riverine flood-affected areas, and nearby communities was selected for non-flood-affected areas. Non-flood area selected from nearby communities with similar socio-economic backgrounds. The location of Bardiaya, Rajapur, is found to be victimized by the Karnali River of western Nepal every year. The focus group discussed and observation was also done. The research area was selected as highly affected by summer floods. Information was collected through a structured questionnaire and an in-depth interview with 3-5-year-old children's households’ mothers or caregivers. Findings/Result: Both areas found malnutrition, but the flood-affected area was more affected than the non-flood area. Every year, the deepest river in Nepal, Karnali, is affected one to three times annually. Its impact on society is to stay in safe places like community centers, school buildings, and Godam for one to four weeks (7 days to 30 days) annually. The main problem was monsoon flooding from June to September. When the Karnali River floods, the level rises and reaches 11 meters. In the riverbank area, residential people leave their homes and stay as refugees. Originality/Value: This is the Ex-post facto research to assure impact of flood on child nutrition which will be a guiding document for the creation of health society. Paper Type: Research paper

Impact of Flood on Children Nutrition

Purpose: Particularly with regard to floods, landslides, drought, forest fires, and hot and cold waves of viral infections every year, Nepal is a very disaster-prone nation due to the high summer precipitation rates. More landslides occur in Nepal's river hills and Terai region throughout the summer (June to September) due to the heavy monsoonal rain that falls during this time. In the up-stem region of rivers, flooding is more likely to occur, and the down-stem region of rivers has a dipping issue. Sedimentation harms homes, agriculture, and human life all at once. The research aims to distinguish nutritional difference among under-five children with and without flood through Weight, Height and Mid-Upper Arm Circumference (MUAC) reading. Design/Methodology/Approach: The study was carried out in a Nepali region that had just experienced severe flooding. The nutritional status of children in flood-affected and non-flood-affected communities was assessed and compared as ex-post facto research. Used mixed methodologies (qualitative and quantitative) to analyse how floods affect in ECD children. Review of relevant literature on the consequences of a natural disaster (flood) on children who were affected by it. Establish the target population, take ethical issues into account, and ask the mother of the children to provide her informed consent. Face-to-face interviews were used to collect information from respondents. The children's height, weight, and mid-upper arm circumference were measured. The information was then analysed using SPSS and Ena (WHO software). Findings/Result: The floods affected children, who measured anthropometry and body mass and prepared results. Review of literature related to flood-affected children and the effects of natural floods (disasters). Define the target population, consider ethical considerations, and obtain informed consent from the children’s mother. The data shows flood-affected children are more malnourished than children in non-flood-affected in the sane social areas. In the Karnali River, unthinkable floods stop human life. During the flooding duration, almost all houses leave their homes for 1 to 4 weeks and stay as refuse in community buildings (community homes, schools, and Godam buildings). According to the Karnali River floods, this condition occurs 1–3 times per year. After every flooding, it takes huge cost for the maintenance of their home, toilet, and handpump to get back to their normal life. Originality/Value: This is the first empirical research in Nepal to compare and analyse the impact of flood on Children's nutrition status to draw the attention of policy maker and different societies working in the area. Paper Type: Review paper

Occurrence, speciation, and controls on arsenic mobilization in the alluvial aquifer system of the Ghaghara basin, India.

High concentrations of arsenic (As) in groundwater are among the long-standing environmental problems on the planet. Due to adverse impacts on the human and aquatic system, characterization and quantification of individual inorganic As species are crucial in understanding the occurrence, environmental fate, behaviour, and toxicity in natural waters. This study presents As concentration and its speciation As(III) and As(V) data, including the interrelationship with other major and trace aqueous solutes from parts of the Ghaghara basin, India. More than half (57%) of the groundwater samples exhibited elevated As concentrations (> 10μg/L), whereas 67.4% of samples have higher As(III) values relative to As(V), signifying a potential risk of As(III) toxicity. The elevated concentration of As was associated with higher Fe, Mn, and HCO3-, especially in samples from shallow well depth. PHREEQC modeling demonstrates the presence of mineral phases such as hematite, goethite, rhodochrosite, etc. Therefore, it is inferred that the release of As from sediment particles into pore water via microbially mediated Fe/Mn oxyhydroxides, and As(V) reduction processes mainly control high As concentrations. The heavy metal pollution indices (HPI) and (HEI) values revealed heavy metal pollution in low-lying areas deposited by relatively younger sediments along the Ghaghara River. Large-scale agricultural practices, overexploitation of groundwater, and indiscriminate sewage disposal, in addition to geogenic factors, cannot be ruled out as potential contributors to As mobilization in the region. This study recommends conducting seasonal hydrogeochemical monitoring and investigating regional natural background levels of As, to precisely understand the controlling mechanistic pathways of As release.

Length-weight relationship and condition factor of a commercial food fish Labeo rohita (Hamilton, 1822) from Ghaghara River, Uttar Pradesh

Length-weight relationship and condition factor of a commercial food fish Labeo rohita (Hamilton, 1822) from Ghaghara River, Uttar Pradesh

Applicabilty of TRMM Precipitation for Hydrological Modeling Using HEC-HMS in Karnali River Basin in Nepal

This study aims to validate the HEC-HMS model in the Karnali river basin of Nepal, while also physically verifying the model parameters for the area. The HEC-HMS model is a semi-distributed physically based model that requires site-specific information about the weather, as well as spatial information on soil and land use. Using Arc-GIS, HEC-HMS, and HEC DSS, a hydrological rainfall runoff model was developed for the Karnali River basin at Asaraghat (DHM station 240) for the period of 1998-2005. Calibration for the time period of 1998-2001 resulted in an NSE value of 73.2% and an R2 value of 84%. Validation for the time period of 2003-2005 resulted in an NSE value of 72.4% and an R2 value of 82.02%. To evaluate the performance of the TRMM 3B42V7 rainfall product, statistical indicators such as NSE and R2 were used. Results showed that the TRMM rainfall data was reliable and had good precision in application to the Karnali River Basin. This study concludes that the TRMM rainfall data can be used as an alternative data source for basins with sparse rain gauge stations in Nepal. The results also suggest that the HEC-HMS modeling tool is good enough to relate rainfall and runoff. The model parameters for each sub-basin and reaches were analyzed with the physical characteristics of the watershed. Minor variations were found within calibrated and calculated Initial abstraction and Muskingum K, x, leading to the verification of the model parameters physically.

Flood susceptibility modeling of the Karnali river basin of Nepal using different machine learning approaches

The Karnali River Basin (KRB) comprises the longest river in Nepal, located south of the Himalayas. Despite its high susceptibility to floods, the basin lacks detailed studies. Proper floodplain management is essential to reduce the impacts due to rising flood frequency, magnitude, and severity aggravated by climate change. This research applies three machine learning techniques, Support Vector Machine (SVM), Random Forest (RF), and Artificial Neural Networks (ANN), to flood event data from the KRB. Ten flood conditioning factors; Aspect, curvature, distance to a river (DTR), normalized difference vegetation index (NDVI), elevation, slope, rainfall, soil, stream power index (SPI), and topographical wetness index (TWI) were selected based on the multicollinearity test. The parameter performance was evaluated using the Cohen Kappa Score, with NDVI having the greatest influence, followed by elevation, DTR, curvature, and TWI. Based on the Area Under the Curve of Receiver Operating Characteristics (AUROC), SVM outperformed RF, ANN, and ANN for FSM. The area of very high flood susceptible areas ranges from 0.8 to 2.5% of the basin area, most of them located in the south with low slopes and elevations. The results of this study suggest the use of SVM for FSM to help with proper floodplain management.

Environmental DNA (eDNA) based fish biodiversity assessment of two Himalayan rivers of Nepal reveals diversity differences and highlights new species distribution records

Although over 180 freshwater fish species have been reported from Nepal, little is known of their ecology and distribution. This information is needed because their diversity may be threatened by developments like hydropower constructions. We conducted Nepal’s first environmental DNA (eDNA) based fish biodiversity assessment in two major river systems- Karnali River (KR), which is still pristine and Trishuli River (TR) with numerous hydropower plants. The eDNA was concentrated by filtering (0.45 μm pore size) two liters of water collected at different sampling points in each study site. A total of 224 eDNA samples (KR = 162 and TR = 62) were collected, from which fish species were identified by 12S rRNA metabarcording approach utilizing Illumina sequencing platform. Alpha and beta diversity of species between two river basins were compared. Also, in KR site, fish (N = 795) were caught, and identified using COI gene based DNA barcoding method- building Nepal’s first fish DNA reference database. Field sampling identified 21 species through morphology and DNA barcoding, where Barilius spp. and Schizothorax spp. were the most abundant. From 244 eDNA samples, 24 Operational Taxonomic Units (OTUs) were identified in TR and 46 in KR with 19 being common to both sites, 27 being unique in KR, and five in TR only. Most fishes were of Cypriniformes and Siluriformes orders, with Barilius spp. and Schizothorax spp. being the most abundant. Long distance migratory fish (Tor spp, Neolissochilus hexagonolepis) and non-native fishes were identified in eDNA samples as well. Alpha diversity in TR was significantly lower than in KR. High beta diversity between the two sites indicated low similarity in fish diversity between the TR and KR. This study demonstrated the utility of eDNA as a non-invasive technique for biodiversity assessment which is particularly useful in areas like Nepal with scarce data on fish species distribution.

Application of water quality index (WQI) and statistical techniques to assess water quality for drinking, irrigation, and industrial purposes of the Ghaghara River, India

Application of water quality index (WQI) and statistical techniques to assess water quality for drinking, irrigation, and industrial purposes of the Ghaghara River, India

Appraisal of Empirical Studies on Land-Use and Land-Cover Changes and Their Impact on Ecosystem Services in Nepal Himalaya

The study of land-use and land-cover change (LULCC) and their impact on ecosystem services (ESs) is vital for Nepal, where the majority of people are dependent on agriculture and services related to the ecosystem. In this context, this paper aims to appraise the empirical studies on land-use and land-cover changes and their impact on ecosystem services in Nepal Himalaya. The study acquired studies from Web of Science and Google Scholar for systematic review. Altogether, 90 scientific studies, including 64 on land use and land cover and 26 on ecosystem services, published between 1986 and 2020 focusing Nepal, were assessed. The results show that there were continual changes in land-cover and land-use types in Nepal, as well as in the pace of development due to natural, anthropogenic, and policy factors. According to the national land-cover scenario, forests tended to increase, whereas agricultural land gradually decreased in recent years, with some of the available agricultural land even being abandoned. The scenario of the agricultural land in the Karnali river basin was different from those of the land in the Koshi and Gandaki basins. In the mid-twentieth century, the expansion of agricultural land and massive deforestation were observed, mainly in the Tarai region. Development works, urbanization, and the rural–urban migration led to the gradual decrease in and abandonment of the available agricultural land in recent decades. Further, this overall scenario has determined in provision of ESs. Forests have the highest value of ES, and community forests have played a vital role in their restoration. The concept of payment for ESs has greatly supported socio-economic development and ecosystem conservation. However, the formulation and implementation of effective landscape planning with suitable policies and enforcement mechanisms is essential to balance the negative impact of LULC on the sustained management of ecosystems and their associated services.

Environmental drivers of spatio-temporal dynamics in floodplain vegetation: grasslands as habitat for megafauna in Bardia National Park (Nepal)

Abstract. Disturbance-dependent grasslands, often associated with hydromorphological and fire dynamics, are threatened, especially in subtropical climates. In the Nepalese and Indian Terai Arc Landscape at the foot of the Himalayas, natural and cultural grasslands serve a viable role for greater one-horned rhinoceros (Rhinoceros unicornis) and for grazers that form prey of the Royal Bengal tiger (Panthera tigris). The grasslands are vulnerable to encroachment of forest. We aimed to establish the effects of environmental drivers, in particular river discharge, river channel dynamics, precipitation and forest fires, on the spatio-temporal dynamics of these grasslands. The study area is the floodplain of the eastern branch of the Karnali River and adjacent western part of Bardia National Park. We created annual time series (1993–2019) of land cover with the use of field data, remotely sensed LANDSAT imagery and a supervised classification model. Additionally, we analysed the pattern of grassland patches and aerial photographs of 1964. Between 1964 and 2019, grassland patches decreased in abundance and size due to encroachment of forest. Outside the floodplain, conversion of grassland to bare substrate coincides with extreme precipitation events. Within the floodplain, conversion of grassland to bare substrate correlates with the magnitude of the annual peak discharge of the bifurcated Karnali River. Since 2009, however, this correlation is absent due to a shift of the main discharge channel to the western branch of the Karnali River. Consequently, alluvial tall grasslands (Saccharum spontaneum dominant) have vastly expanded between 2009 and 2019. Because the hydromorphological processes in the floodplain have become more static, other sources of disturbances – local flooding of ephemeral streams, anthropogenic maintenance, grazing and fires – are more paramount to prevent encroachment of grasslands. Altogether, our findings underscore that a change in the environmental drivers impact the surface area and heterogeneity of grassland patches in the landscape, which can lead to cascading effects for the grassland-dependent megafauna.