Major River Basins Research Articles

Evaluation of Rainfall Variability Over Major River Basins of India Using Multi Temporal Satellite Data Products

ABSTRACTHigh resolution remotely sensed rainfall data is indispensable to accurately monitor rainfall variability at a river basin scale under climate change. The aim of the study is to assess the change in rainfall climatology and determine the performance of three GPM rainfall products (IMERG Final_Run, GSMaP_Gauge and recently developed GSMaP_ISRO) against in situ observation over major Indian River basins for the monsoon season rainfall during 2000–2020. The analysis provides valuable insights into the issues in the rainfall products and their performance under varying rainfall intensity (low, moderate and heavy) and orography. Results indicate that mean monsoon rainfall is better represented in GSMaP_ISRO than IMERG Final_Run and GSMaP_Gauge estimates. GSMaP_ISRO outperformed IMERG Final_Run and GSMaP_Gauge with smaller root‐mean‐square error and higher correlation coefficient. It was observed that the performance of GPM rainfall is influenced by rainfall intensity and terrain height of basins. In particular, for high rainfall occurrence, the Brahmaputra and Barak basins in northeast India exhibited large uncertainties in IMERG Final_Run and GSMaP_Gauge products. The statistical evaluation of different rainfall scores (POD, FAR and CSI) suggested that the GSMaP_ISRO rainfall has significant skill over Indian river basins. A significant improvement is observed over Brahmaputra (RMSD = 34.46, CC = 0.92, FAR = 0.26), Barak and others (RMSD = 65.75, CC = 0.95, FAR = 0.29) and Cauvery basin (RMSD = 23.1, CC = 0.8, FAR = 0.15) for GSMaP_ISRO estimates. These findings provide valuable information on the accuracy of GPM rainfall necessary for hydro‐meteorological applications.

Unveiling hydrological responses in Madagascar’s major river basins: addressing data scarcity and land-use change impacts

Insufficient observed hydro-climatological data and studies on land use and land cover change (LULCC) hinder the understanding of environmental changes at the Major River Basins in Madagascar (MRBM). This paper assesses the impact of LULCC on water resources across the MRBM. The ability of the Soil and Water Assessment Tool (SWAT) model to simulate streamflow is evaluated to obtain long-term and consistent hydrological information across the country. Moreover, this study emphasized the process of single-gauge calibration and dealing with uncertainty on a large river basin scale. Despite the lack of data, the model efficiently simulated streamflow, achieving high predictive accuracy in 8 basins out of 12 during calibration and validation. By 2050, a major change in LULC is predicted across the MRBM, which is expected to significantly alter the water balance. Major causes of LUCC and measures to address these changes are also investigated. We recommend basin-specific water management plans.

Community characteristics of macrobenthos and ecosystem health assessment in ten reservoirs of Henan Province, China

Assessing the eco-health of regional reservoirs is essential for sustainable water resource utilization and water security, particularly in water-scarce areas. This study constructed a Benthic Index of Biotic Integrity (B-IBI) based on the community characteristics of macrobenthos in ten large and medium-sized reservoirs across four major river basins in Henan Province, China. A total of 90 taxa were identified, representing 3 phyla, 6 classes, 17 orders, 45 families and 81 genera. The B-IBI was derived from five key metrics: the number of crustacean and mollusca taxa, Intolerant %, the BI index, the BMWP index, and the Shannon–Wiener index. The B-IBI scores across 44 sites in the ten reservoirs ranged from 0.35 to 3.99. The assessment classified two reservoirs (QTH and HKC in the Yellow River basin) as poor, whereas one reservoir (QP in the Huai River sbasin) was classified as excellent. The B-IBI index effectively distinguished impaired sites from reference sites, supporting its suitability for eco-health assessments of reservoirs in Henan Province.

Climate-Resilient Rice Cultivation in India: Overcoming Challenges for Sustainable Food Security

Climate change poses a significant threat to rice cultivation in India, impacting yield and production due to rising temperatures, erratic rainfall and increasing salinity. India, the world's second-largest rice producer, faces challenges in maintaining rice output amid these environmental stresses. Studies highlight temperature increases leading to significant yield reductions, with potential losses in major river basins. Climate-resilient agriculture (CRA) practices, such as direct-seeded rice, drought-tolerant varieties and integrated crop diversification, offer solutions to mitigate these impacts. CRA emphasizes water conservation, reduced labour costs and improved input efficiency. Climate-resilient rice varieties, particularly those tolerant to salinity and submergence, are crucial for sustaining food security and farmer livelihoods in vulnerable regions. Despite benefits, barriers to adoption include policy issues, lack of awareness, inadequate infrastructure and limited access to technology. Collaborative efforts between government, NGOs and local communities are essential for fostering the widespread implementation of these practices to ensure long-term agricultural sustainability.

A new species of Phenacorhamdia (Siluriformes: Heptapteridae) from the Juruena River basin, with insights into its phylogenetic position

Heptapteridae is a group of small to medium-sized neotropical catfish composed of 23 genera and 238 valid species, classified into two subfamilies: Rhamdiinae and Heptapterinae. Phenacorhamdia represents small heptapterids and is composed of 14 valid species distributed across all major river basins in South America. In this paper, we add another species to the genus, described from the Juruena River basin, Mato Grosso state, Central Brazil. This species is distinguished from its congeners by having multicuspid teeth, 47–52 vertebrae, maxillary barbel not reaching to pectoral-fin origin, and absence of a short extension of the first pectoral-fin ray. Additionally, a brief discussion on its putative phylogenetic position, based on UCEs dataset, is provided.

The Relationship of Fish Functional Traits, Physicochemical Characteristics and Exotic Fish (Micropterus salmoides and Lepomis macrochirus)

An invasive species is defined as a biological species introduced, most often through human action, that causes direct harm, such as reducing or driving native species to extinction. This introduction can result in long-term changes to ecosystem structures and ultimately contribute to a decline in biodiversity within areas where it was not previously present. Thus, continuous monitoring and management are essential. This study examined the impact of two exotic species, largemouth bass (Micropterus salmoides) and bluegill (Lepomis macrochirus), on fish diversity in rivers across South Korea. Data from the “Stream Ecosystem Survey and Health Assessment” project, which was conducted along five major river basins between 2013 and 2021, were analyzed. The data were divided into three periods: 2013–2015, 2016–2018, and 2019–2021, covering a total of 960 sites. The results revealed that largemouth bass and bluegill were present at 360 sites (37.5%) from 2013 to 2015, 325 sites (33.9%) from 2016 to 2018, and 356 sites (37.1%) from 2019 to 2021. Additionally, when comparing sites where exotic fish were present with those where they were absent, the average number of native species was slightly higher in areas where these invasive species were present, yet the average Fish Assessment Index (FAI) value was lower. Statistically significant differences were observed in fish diversity, especially in trophic and tolerance traits. This study provides valuable insight into the impact of invasive species on South Korean river ecosystems and offers important information for developing future conservation and management strategies for biological resources.

Genetic diversity of the Khorat snail-eating turtle (Malayemys khoratensis) in Thailand.

Malayemys khoratensis is a freshwater turtle species endemic to northeastern Thailand and Lao PDR. While M. khoratensis is relatively common and widespread in Thailand, its population size and demographic trends remain largely unknown, as direct population estimates are lacking. This species faces significant threats from consumption, exploitation, and trade. Therefore, this study aims to investigate the genetic diversity, population structure, and demographic trends of M. khoratensis in northeastern Thailand, using two mitochondrial DNA genes, Cyt b and ND4. We grouped the turtles based on three major river basins in northeastern Thailand: Mun, Chi, and Northeast Mekong to assess population structure and test the isolation-by-basin hypothesis. The Cyt b and ND4 genes of 49 M. khoratensis individuals across 15 provinces in Thailand were sequenced, and 15 sequences from a previous study of Ihlow et al. (2016) were included into the analyses. We constructed a haplotype network from the concatenated sequences and analyzed the population structure with the analysis of molecular variance (AMOVA). Additionally, we used a Bayesian Skyline plot (BSP) analysis to estimate the effective female population size and explore the demographic history of this species. Our analysis identified 13 unique haplotypes defined by 26 polymorphic sites from 64 samples. The total haplotype diversity for M. khoratensis was 0.819, while nucleotide diversity was 0.0031. The haplotype network and AMOVA revealed no distinct population structure among the river basins, suggesting gene flow across these regions. The BSP estimated a stable effective female population size of approximately 130,000 individuals since around 100,000 years ago (late Pleistocene). Our findings indicated no significant population structure by river basin, which may be due to natural movement between basins or potential human-mediated translocations linked to the turtle trade. The demographic trend of M. khoratensis appears to have been stable over time. However, given the ongoing exploitation of this species, we recommend regular monitoring of population trends to support its long-term survival.

Ecological risks caused by neonicotinoid pesticides in sediments: A case study of freshwater basins in China.

Neonicotinoid insecticides (NNIs) are extensively used in agricultural production in China due to their selective neurotoxicity towards target insects. In recent years, the rapid development of agriculture has increased the use and residue of NNIs. Consequently, the sediment environment, serving as the ultimate sink, is significantly impacted by NNIs. Upon release into the environment, NNIs can enter the human body through the food chain, posing potential ecological and human health risks. This study analyzed 79 sediment samples from two major river basins in North and South China, the Liaohe River basin in Liaoning Province and the Jianjiang River basin in Guangdong Province. The content, composition, distribution, and source of eight NNIs were analyzed, and assess the ecological and human health risks of the target compounds in these regions. The results indicated that the average concentration of NNIs in the sediments of the Jianjiang River basin (2.34μg/kg) is slightly higher than that of the Liaohe River basin (2.32μg/kg), and the sources of NNIs in the two areas were different, with differences in the sources of NNIs likely attributable to varying types of agricultural production. The risk assessment revealed that the ecotoxicological and public health risks were more pronounced in the Jianjiang River basin compared to the Liaohe River basin, underscoring the critical need for surveillance and management of hazardous substances like NNIs. The insights findings from this study can provide scientific guidance for the risk evaluation and environmental management of NNIs.

Correction: Haplotype analysis based on the D-loop region of mitochondria of the fish Wallago attu (Bloch and Schneider, 1801) collected from four major river basins of the Northern Part of the Eastern Ghats, India

Correction: Haplotype analysis based on the D-loop region of mitochondria of the fish Wallago attu (Bloch and Schneider, 1801) collected from four major river basins of the Northern Part of the Eastern Ghats, India

Improving long-term prediction of terrestrial water storage through integration with CMIP6 decadal prediction

Accurate climate prediction is crucial for terrestrial water storage (TWS) decadal prediction, which contributes to the sustainable development of hydrological infrastructure. Although the initial memories from atmosphere, ocean and land surface are important sources of climate predictability, their impacts on the decadal hydrological prediction still remain unknown. Here, climate predictions with different initialization strategies from the sixth Coupled Model Intercomparison Project (CMIP6) are incorporated into the hydrological predictions over global major river basins through the elasticity framework. Integrations of the climate initialization and external forcings can improve the TWS prediction skill (Nash-Sutcliffe efficiency) by 0.14–0.24 over 69 % basins against a reference forecast without any climate prediction information, especially over high-latitudes at long lead time. Specifically, climate initialization results in a higher skill for TWS prediction over 62.5 % of basins, while considering the Atlantic or Pacific sea surface temperature information is benefit to the hydrological prediction over 38 %–90 % of basins at different lead times. Our findings imply that reliable hydrological decadal prediction can be achieved if skillful climate prediction that originates from initial conditions, external forcings and specific climate variability has been utilized appropriately.

Rain event detection and magnitude estimation during Indian summer monsoon: Comprehensive assessment of gridded precipitation datasets across hydroclimatically diverse regions

Accurate precipitation estimates are quintessential for hydrologic modeling and climate studies. Different gridded precipitation products are available in any region, and selecting the best one is essential for hydroclimatic modeling and analysis. In the current study, observation- (APHRODITE), reanalysis- (IMDAA, ERA5-Land, PGF), satellite-based (IMERG, CHIRPS, PERSIANN-CDR), and hybrid (MSWEP) gridded precipitation products with different spatial and temporal resolutions are evaluated using several continuous, categorical, graphical, and interval-based performance measures towards detecting Indian Summer Monsoon Rainfall (ISMR) events and estimating their magnitudes for the subcontinent of India, considering IMD gauge-based gridded data as reference product. We confine our analysis to the monsoon season (i.e., June to September), the principal rainy season in the Indian sub-continent. The dearth of data and limited rain gauge-based observations from non-uniform sparse monitoring networks across India necessitated grid-to-grid comparative evaluations instead of point-to-grid assessments. We propose a new ranking framework to determine the suitability of precipitation datasets for twenty-seven hydroclimatic regions comprising homogeneous rainfall zones, Köppen-Geiger climate zones, and major river basins. Results from the comprehensive evaluation suggest that (1) APHRODITE, MSWEP, and ERA5-Land best approximate precipitation event occurrences across India, (2) MSWEP and ERA5-Land are most suitable (highest rank) alternatives at the regional level, while APHRODITE is found to be next suitable dataset owing to its persistent dry bias, (3) CHIRPS and IMERG have reasonably lower rank score across India, (4) close agreement of examined datasets is noted over semi-arid and sub-humid regions (e.g., peninsular and central India), whereas ERA5-Land, IMDAA, and APHRODITE fail to detect and reproduce the intensity of the events along the west coast and northeastern India, (5) PGF and PERSIANN-CDR are the least situated datasets. Moreover, the present study provides a unique and innovative perspective to characterise the precipitation over a vast topographic, ecologic, and climatic gradient region like India.

Factors influencing carbon and water use efficiency in changing environments

IntroductionVegetation plays a crucial role in terrestrial ecosystems, acting as a vital link connecting the lithosphere, hydrosphere, and atmosphere in terms of energy flow and material cycling. Changes in surface vegetation significantly regulate the water cycle, energy flow within terrestrial surfaces, and global carbon balance.MethodsThis study focuses on nine major river basins in China to quantitatively investigate the impacts of climate factors, vegetation dynamics, and land use changes on carbon use efficiency (CUE) and water use efficiency (WUE).ResultsThe primary controlling factors of WUE trends are NDVI (average contribution: 33.75% ± 6.90%) and VPD (average contribution: 28.04% ± 3.98%). NDVI predominates in the Haihe, Yellow River, Yangtze River, Pearl River, and Songliao River basins, while shortwave radiation (Srad) dominates in the southeastern rivers and inland river areas, and humidity (Shum) in the southwestern river basins. For CUE trends, the main controlling factors are Srad (average contribution: 36.46% ± 3.40%) and precipitation (Pre) (average contribution: 26.72% ± 5.20%). NDVI negatively influences the Huaihe River and southeastern river basins, while Pre negatively influences the Songliao River and Yellow River basins, and Srad negatively influences the Huaihe and southwestern river basins. Pre predominates in the Huaihe, Songliao, Haihe, southwestern river basins, and inland river areas, while Srad predominates in the Pearl River, Yangtze River, and Yellow River basins.DiscussionClimate factors and vegetation dynamics have significant regional impacts on WUE and CUE across different river basins, especially the roles of NDVI and VPD on WUE, and Srad and precipitation on CUE. These differences underscore the importance of developing region-specific management strategies to optimize ecosystem services in each basin.

Applicability analysis of comprehensive drought index based on GRACE data in ten major river basins in China

As hydroclimatic extremes, drought triggered by climate change and human activities are recurrent over China. Selecting an appropriate comprehensive drought index is an important measure to comprehensively monitor drought characteristics. Precipitation and Terrestrial Water Storage Anomalies (TWSA) are important variables for assessing drought triggered by water deficiency in the atmosphere and terrestrial systems. The study aims to compare and discuss the applicability of drought index based solely on TWSA (DSI) and based on the combined effects of precipitation and TWSA (CCDI) in monitoring comprehensive drought in China. The results reveal that precipitation anomalies do not align with TWSA in arid basins, while they are synchronized in humid basins. CCDI reveals more favorable spatiotemporal agreement with the traditional drought indices, whereas DSI shows more consistency with common drought indices in humid basins. CCDI and DSI are suitable for assessing comprehensive drought in arid and humid basins, respectively. Moreover, almost both DSI and CCDI successfully monitored major drought periods in humid and arid basins during 2002–2006 and 2013–2017, respectively. Overall, this study highlights the applicability of CCDI and DSI in comprehensive drought assessment in arid and humid basins, respectively, providing valuable support for optimizing water resources utilization, management, and drought resistance decision-making.

Linking curve number with environmental flows: a novel approach.

Change in flow regime is one of the major reasons which influence the services offered by rivers and integrity of their aquatic ecosystems requiring certain amount of flow in the river known as environmental flow. In this study, the environmental flows described by Tennant's method are correlated with a very versatile index defined in terms of Curve Number (CN) that incorporates hydrometeorological and geomorphological characteristics of catchment. Parameter CN is commonly known to be closely related with catchment characteristics (viz., land use, soil type, etc.). The rainfall-runoff data of 17 catchments from five major Indian river basins (i.e., Brahmani-Baitarani, Godavari, Mahanadi, Mahi, and Narmada) of low flow season (October-June) are used to derive the relationship between percentage of average annual flow (%AAF) and CN. The %AAF is seen to increase linearly with increasing CN, and vice versa, for all catchments and the correlation (R) is found to be greater than 0.7 for 16 (out of 17) catchments. The correlation between %AAF and CN is maximum for Dhariawad (R2 = 0.899) and Baronda (R2 = 0.814) catchments, indicating excellent relationship between %AAF and CN, which can be useful for the environmental flow prediction based on catchment characteristics. The existence of such a relationship is further strengthened by the relation established between the standard normal deviate of CN and the Standard Flow Index (SQI), a variation of %AAF, using the same field data.

Haplotype analysis based on the D-loop region of mitochondria of the fish Wallago attu (Bloch and Schneider, 1801) collected from four major river basins of the Northern Part of the Eastern Ghats, India

Haplotype analysis based on the D-loop region of mitochondria of the fish Wallago attu (Bloch and Schneider, 1801) collected from four major river basins of the Northern Part of the Eastern Ghats, India

Remote Sensing-Based Multiscale Analysis of Total and Groundwater Storage Dynamics over Semi-Arid North African Basins

This study evaluates the use of remote sensing data to improve the understanding of groundwater resources in climate-sensitive regions with limited data availability and increasing agricultural water demands. The research focuses on estimating groundwater reserve dynamics in two major river basins in Morocco, characterized by significant local variability. The study employs data from Gravity Recovery and Climate Experiment satellite (GRACE) and ERA5-Land reanalysis. Two GRACE terrestrial water storage (TWS) products, CSR Mascon and JPL Mascon (RL06), were analyzed, along with auxiliary datasets generated from ERA5-Land, including precipitation, evapotranspiration, and surface runoff. The results show that both GRACE TWS products exhibit strong correlations with groundwater reserves, with correlation coefficients reaching up to 0.96 in the Oum Er-rbia River Basin and 0.95 in the Tensift River Basin (TRB). The root mean square errors (RMSE) were 0.99 cm and 0.88 cm, respectively. GRACE-derived groundwater storage (GWS) demonstrated a moderate correlation with observed groundwater levels in OERRB (R = 0.59, RMSE = 0.82), but a weaker correlation in TRB (R = 0.30, RMSE = 1.01). On the other hand, ERA5-Land-derived GWS showed a stronger correlation with groundwater levels in OERRB (R = 0.72, RMSE = 0.51) and a moderate correlation in TRB (R = 0.63, RMSE = 0.59). The findings suggest that ERA5-Land may provide more accurate assessments of groundwater storage anomalies, particularly in regions with significant local-scale variability in land and water use. High-resolution datasets like ERA5-land are, therefore, more recommended for addressing local-scale heterogeneity in regions with contrasted complexities in groundwater storage characteristics.

Concurrent droughts across Major River Basins of the World modulated by El Niño–Southern Oscillation

Droughts are among the costliest natural disasters with far-reaching impacts. Focusing on the influence of El Niño–Southern Oscillation (ENSO) on worldwide droughts, this paper presents a formulation of the complex network of concurrent droughts across the Major River Basins (MRBs) of the World. Specifically, concurrent droughts are measured by event synchronization and interconnections of concurrent droughts are determined by significance test. Event coincidence analysis is incorporated into interconnections to quantify the effects of El Niño and La Niña events. A case study is devised for the 3-monthly standardized precipitation index (SPI) of Global Drought and Flood Catalogue during the period from 1950 to 2016. The results highlight that owing to the synchronization of droughts, there exist nine communities of the MRBs, each covering MRBs across different continents. While the correlation between SPI and ENSO exhibits mixed patterns for MRBs grouped by continent, there exist distinct patterns of correlation for MRBs grouped by community. Overall, 28.88% of concurrent droughts tend to be modulated by El Niño events, especially over MRBs in South-West Pacific, South Africa, northern South America and South Asia. In the meantime, 23.51% of concurrent droughts tend to be modulated by La Niña events, especially over MRBs in the United States, southwestern South America, northern China and Central Asia. The modulation of El Niño and La Niña is confirmed by composite analysis of SPI and detailed analysis of the Yangtze River Basin. Overall, the complex network provides useful information for drought forecasting and disaster mitigation.

Spatially varying effect of soil moisture-atmosphere feedback on spring streamflow under future warming in China

Soil moisture–atmosphere feedback (SAF) is expected to accelerate warming in the future, but its influences on the terrestrial water cycle over non-traditional hotspots of land–atmosphere coupling (e.g., East Asia) remains elusive due to strong heterogeneity and uncertainties at model grid scales. Here we show robust evidence of the integral effects of SAF on streamflow under future warming across major river basins in China. Based on high-resolution hydrological modelings driven by CMIP6 simulations with/without land–atmosphere coupling, SAF is projected to significantly increase spring streamflow by 28–58% in mid-latitude China, but decrease it by 12–48% in other regions. Such contrary effects are attributed to the soil moisture-precipitation interaction, which causes spatially opposite changes in precipitation through thermodynamic (e.g., ascending/descending vertical motions) and thermal (e.g., weakened meridional water vapor transport) atmospheric adjustments. Our result highlights the importance of SAF in altering freshwater resources even in locations not typically considered to be SAF hotspots.

Assessing terrestrial water storage dynamics and multiple factors driving forces in China from 2005 to 2020

In the context of global warming, comprehending the dynamics of terrestrial water storage (TWS) and its responses to natural and anthropogenic factors is paramount for hydrological research and the management of water resources in China. This study utilized GRACE (Gravity Recovery and Climate Experiment)/GRACE-Follow On (GRACE-FO) satellite data to analyze terrestrial water storage across nine basins in China from 2005 to 2020 at multiple temporal and spatial scales. Subsequently, employing a Geographic detector model, potential influencing factors were identified, and an enhanced Geographically Weighted Regression (GWR) method was proposed for attributing changes in TWS in China. The findings reveal a consistent declining trend in TWS based on GRACE/GRACE-FO data across different temporal scales, with the most pronounced decreases observed in August and September. Geographic Detector analysis unveils significant interactions among various environmental factors, with climate variables playing a pivotal role in modulating hydrological characteristics of major river basins, where rising temperatures can exacerbate the severity of precipitation events, thus increasing the risk of floods and droughts. Moreover, analysis of the primary influencing factors indicates significant impacts of population density and topography on water resources in the southeastern and southwestern regions, particularly amidst increasing human activities and urbanization expansion. The results of this study are crucial for comprehending the dynamic changes and mechanisms of TWS in China, as well as for formulating water resource management strategies.

Revisiting moated sites in Northeast Thailand: integrating spatial analysis with previous and new research insights

Moated sites in northeast Thailand serve as pivotal evidence of human–environment interaction since the Iron Age and have been subject to extensive study. This research conducts a comprehensive examination of moated sites, aiming to analyze their spatial characteristics and relationships with physical environmental factors across various scales, including regional and major river basins. To achieve these goals, advanced GIS tools including average nearest neighbor (ANN) analysis, kernel density estimation (KDE), standard deviational ellipse (SDE) analysis, and the Kruskal–Wallis test are employed. By incorporating a dataset of 468 moated sites and expanding the geographic scope beyond previous studies, this research offers new insights into settlement patterns and environmental interactions. Contrary to earlier interpretations suggesting random dispersion, the study’s findings reveal a clustering pattern, indicating intentional spatial organization by ancient communities. The study also highlights the influence of rainfall on the number of moats, with multiple moats more common in lower rainfall areas and single moats in higher rainfall regions. Additionally, the results observe that sites with more moats are typically found at higher elevations, although no significant correlation between elevation and site size was identified, challenging previous studies' conclusions. These results underscore the importance of local environmental conditions, such as rainfall and elevation, in shaping the distribution and characteristics of moated sites. The findings highlight the complex interplay between environmental factors and human settlement strategies, emphasizing the role of water management in ancient communities.