Transboundary Basins Research Articles

Teleconnections of Atmospheric Circulations to Meteorological Drought in the Lancang-Mekong River Basin

The Lancang-Mekong River Basin (LMRB) is one of the major transboundary basins globally, facing ongoing challenges due to flood and drought disasters. Particularly in the past two decades, the basin has experienced an increased frequency of meteorological drought events, posing serious threats to the local socio-economic structures and ecological systems. Thus, this study aimed to analyze the meteorological drought characteristics in the LMRB and identify the impact and correlation of atmospheric circulation on the meteorological drought in the basin. Specifically, the different levels of meteorological drought events were defined using the Run Theory based on the seasonal and annual SPEI from 1980 to 2018. The time lag correlation between meteorological drought events and the EI Nino-Southern Oscillation (ENSO), Arctic Oscillation (AO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO), were analyzed in the LMRB. Our results indicated that, from a temporal perspective, the period from November to April of the following year was particularly prone to meteorological droughts in the basin. In terms of spatial distribution, the primary agricultural regions within the basin, including Thailand, Eastern Cambodia, and Vietnam, were highly susceptible to meteorological droughts. Further analysis revealed a teleconnection between drought events in the LMRB and atmospheric circulation factors. The sensitivity of the basin’s drought timing to its response decreased in the order of the ENSO > AO > NAO > PDO. In general, the ENSO had the most substantial influence on drought events in the basin, with the strongest response relationship, while the upper reaches of the basin displayed the most significant response to the AO; the occurrence and progression of meteorological droughts in this area synchronized with the AO. These findings enhance our understanding of drought-prone areas in the LMRB, including the meteorological factors and driving mechanisms involved. This information is valuable for effectively mitigating and managing drought risks in the region.

Transnational governance standards in ensuring sustainable development and operation of hydropower projects in transboundary basins

The notion of “transnational” law encompasses a sophisticated corpus of globally applicable rules, standards and safeguards, often informal in origin, which are widely accepted around the world and supported across a range of business sectors and civil society constituencies. The recent proliferation of such “transnational” law extends to the hydropower sector, where normative standards and safeguards increasingly apply to promote and certify sustainable practices in the development and operation of hydropower projects. Such projects are associated with significant environmental and social impacts and the projected increase in hydropower investments, mainly in emerging economies, will require effective supplemental regulatory tools. Many such projects will be located in, or impact upon, international rivers, thereby adding a further layer of complexity regarding their effective regulation and increased the risk of inter-State disputes over the equitable use of shared waters. Such complexity and risk will be exacerbated by increased uncertainty due to climate change. Thus, the existence of widely accepted transnational standards, which are relevant and applicable to hydropower development globally, can play a key role in building trust between watercourse States and in promoting greater transboundary water cooperation. This article explores the potential role of transnational standards in improved regulation of environmental and social impacts associated with hydropower projects located on international watercourses and the extent to which such standards cohere with established and emerging requirements of international water law. It thus examines the synergies arising between these informal and formal regulatory frameworks with a view to developing a better understanding of their interaction in practice. In so doing, it focuses on two key categories of applicable transnational regime: a sustainability certification and labeling scheme dedicated to hydropower projects and operated by the Hydropower Sustainability Council; and MDB environmental and social safeguard standards imposed upon major water-related projects, including hydropower projects, particularly those adopted by the World Bank and the European Bank for Reconstruction and Development (EBRD).

Environmental Radioactivity, Ecotoxicology (238U, 232Th and 40K) and Potentially Toxic Elements in Water and Sediments from North Africa Dams

The natural radioactivity of 238U, 232Th and 40K was measured in water and sediment samples collected from Sidi Salem dam (Tunisia) and Aïn Dalia dam (Algeria) in the Tuniso-Algerian transboundary basin. The samples were measured using a TERRA detector of gamma, beta, and alpha rays, and atomic absorption and gamma-ray spectrometry were used to analyze the levels of radionuclides and toxic elements, respectively. Potentially toxic elements (Fe, Pb, Zn, Ni, Cr, Cu and Cd) and associated health risks in surface water and sediment of dams were investigated in this present study. The concentrations of Fe, Pb, Zn, Ni, Cr, Cu and Cd in surface water ranged from 5.430 to 9.700 mg·L−1, 0.022 to 0.168, 0.018 to 0.142, 0.065 to 0.366, BDL to 0.0351, BDL to 0.071 and BDL to 0.048 mg·L−1, respectively. In the sediments, the concentrations of Fe, Pb, Zn, Cu, Ni, Cd and Cr were of the order of 136.7, 3.41, 3.22, 0.213, 0.182, 0.15 mg·L−1 and BDL, respectively. The mean radioactivity rates in the water samples were 1.72, 0.068 and 94.6 Bq·L−1 for 238U, 232Th and 40K, respectively (Tunisia dam), and were 1.9, 0.09 and 131.43 Bq·L−1 for 238U, 232Th and 40K, respectively (Algeria dam). The mean 238U, 232Th and 40K radioactivity concentrations measured in the sediment samples were 2.67, 0.18 and 197.87 Bq·kg−1, respectively (Tunisian dam), and were 4.34, 0.27 and 287.61 Bq·kg−1, respectively (Algeria dam). The activity concentration of 40K was higher than that of 238U and 232Th for the water and sediment samples. The activity concentrations follow the order 40K > 238U > 232Th. The cumulative impact of these radio-geochemical elements can cause immediate serious problems in the ecosystem due to their high potential toxicity to the environment and human health in this study area and can be transposable to any other similar region. A good knowledge of monitoring quality and quantity for transboundary water resources and international collaborations are essential to safeguard human health (women’s breast cancer, thyroid cancer, neurological impact) and avoid conflicts, especially during climatic upheavals of drought.

An approach to complex transboundary water management in Central Asia: Evolutionary cooperation in transboundary basins under the water-energy-food-ecosystem nexus

Water-related issues in transboundary basins are generally complicated by the challenges of climate change, the historical evolution of the basin characteristics, and the different interests of the riparian countries. Therefore, dealing with water-sharing and water cooperation problems among basin countries needs to be based on multi-factor system analysis in the context of regional water, energy, food (land) resources, and ecosystems. In the present study, the Aral Sea basin in Central Asia, where transboundary water problems are extremely prominent and complex, was selected as the research area. Firstly, the characteristics of the water-energy-food-ecosystem nexus of the Aral Sea basin are analyzed. Then, based on the game theory, a multi-objective game model is constructed, and the multi-objective evolutionary game process and evolutionary stable strategies (ESSs) of both the upstream and downstream countries are explored. Finally, the evolutionary stable strategy under the intervention of the basin commission is simulated. The results show that there are obvious reciprocal feedbacks among water, land, energy, and ecosystem in the Aral Sea basin, and the uneven distribution of natural resources, fragile ecosystems, and conflicting demands of multiple actors lead to the unstable evolution of the nexus. Driven by the maximization of upstream and downstream countries’ respective interests, the optimal stabilization strategy of the system cannot be realized. Whereas, the introduction of the basin commission intervention and its restraint mechanism is conducive to promoting cooperation and maximizing the overall benefits of the basin. The incentives and penalties of the basin commission have significant effects on whether the system can reach Pareto optimality, and higher incentive coefficient and penalty coefficient help the system converge to the ideal state more quickly. The evolution of the water-energy-food-ecosystem nexus based on the perspective of the whole basin can provide theoretical support for dealing with the transboundary water conflicts, and the cooperation strategy aiming at maximizing the overall benefits of the basin can provide decision-making basis for promoting transboundary water cooperation and synergistic development of the water-energy-food-ecosystem nexus.

Integration of the Water Evaluation And Planning System Model with the Nash Bargaining Theory for Future Water Demand and Allocation in the Kabul River Transboundary Basin under Different Scenarios

Integration of the Water Evaluation And Planning System Model with the Nash Bargaining Theory for Future Water Demand and Allocation in the Kabul River Transboundary Basin under Different Scenarios

Flood Inundation and Streamflow Changes in the Kabul River Basin under Climate Change

The Kabul basin yields around 16% of the total annual water availability in Pakistan. Changing climate will alter the precipitation regime in terms of intensity and frequency, which will affect the water yield and cause flood hazards. Against this background, this study aims to quantify the impacts of changing climate on the water yield, its timings, and, more importantly, the associated flood hazards in the transboundary Kabul basin. For this, we used a rainfall-runoff inundation (RRI) model coupled with the snow and glacier melt routines and drove it for historical and future climates simulated by the atmosphere-only general circulation model (AGCM) at 20 km spatial resolution. The model simulations reveal that rainfall runoff contributes around 50% of the annual flows, and the rest is contributed by glaciers and snow melts. Annual precipitation is projected to increase by 14% from 535 mm, whereas temperatures will rise by 4.7 °C. In turn, the Kabul River flows will only increase by 4% to 1158 m3s−1 from 1117 m3s−1, mainly due to an increase in winter flows. In contrast to a minute increase in the mean river flows, the maximum flood inundation area is projected to increase by 37%, whereas its depth will rise between 5 and 20 cm.

Application of eco-compensation to control transboundary water pollution in water diversion projects: The case of the Heihe River transfer project in China

Controlling transboundary water pollution is particularly crucial for the sustainable development of diversion basins, while eco-compensation is an essential incentive for multistakeholder transboundary water pollution control. Considering the dynamics of the various actors' pollution control behavior in the Heihe River water transfer project and utilizing differential game theory, we construct a baseline strategy, a horizontal eco-compensation strategy, and an incentive coordination strategy under scenarios with and without authority incentives. The corresponding equilibrium solutions are then determined, and comparisons are made between the payoffs of the players in the six different structures, thus defining the optimal scenario for the different programs. In the case of the largest ecological water transfer project of the Heihe River in Northwest China, according to the research findings, (1) when eco-compensation is funded through a single source, incentive coordination scenarios can contribute effectively to water pollution control instituted by the main participants in water diversion projects; when multiple financing sources are available, horizontal ecological compensation scenarios are more compatible with the individual interests of local municipalities to improve the water quality environment. (2) Water-receiving cities voluntarily eco-compensate for water-supplying cities, and this incentive structure for eco-compensation facilitates a significant improvement in the effectiveness of water pollution control and therefore the harmonious promotion of sustainable economic and environmental development in eco-fragile areas. (3) Water transfer projects, for which the two participants are at widely.different levels of development and the environment is inherently fragile, can facilitate, via an eco-compensation mechanism that combines horizontal and vertical scenarios, sustainable development-oriented policies for eco-compensation systems in which the authority participates as a third-party game player. The research supports the establishment of policies for the governance of the transboundary water diversion project basins to address conflicts in water pollution management.

Hydrological responses to the synergistic climate and land-use changes in the upper Lancang river basin

Climate change trends in the upper Lancang river basin (LRB), a high-mountain area, are prominent on a global scale, and climate-induced land use change with increasing cropland and migration has been observed in the past decades and is expected to expand in the future. We assessed land use and sediment yield from the basin in the past and future under the synergistic impact of projected climate change and associated land use change. We found that the transition from grassland and forest to cropland under climatic change favorable to agriculture can be the topmost contributor to the sediment yield increase from the upper LRB, with an increaisng rate of 40.6% from the entire area and as high as 118% in some sub-areas. As the baisn serves as the source area of the Lancang-Mekong River Basin (LMRB), we call for coordinated management throughout the entire LMRB, given the complex sediment dynamics crossing scales, affected by both climate change and socioeconomic development in trans-boundary basin.

Water-related problems of Central Asian countries in the transboundary basin of the Syrdarya river

Water-related problems of Central Asian countries in the transboundary basin of the Syrdarya river

An assessment of long-term and large-scale wetlands change dynamics in the Limpopo transboundary river basin using cloud-based Earth observation data

Significant progress has been made in monitoring and assessing the effects of land use and land cover (LULC) changes on wetland extent. However, our understanding of wetland within the transboundary basins has been limited by the scarcity of available data on their dynamic changes over time. This study aimed to address this gap by analyzing the long-term and large-scale spatio-temporal extent of wetland in the Limpopo transboundary river basin (LTRB) over a 20-year period (2000–2020). To achieve this, we utilized the Google Earth Engine (GEE) cloud-computing platform and various remotely sensed data. The study had two primary objectives; (1) to examine LULC changes over time using machine learning algorithms applied to multisource remotely sensed data in GEE, and (2) to assess the relationship between LULC changes and the extent of wetlands in the basin. A total of nine land cover classes were identified, including shrublands, croplands, bare-surface, wetlands, sparse vegetation, tree cover, built-up areas, and grasslands. Shrublands covered 76–82% of the LTRB. On the other hand, wetlands and sparse vegetation were the least dominant, with proportions ranging from 0.3 to 2%. The overall accuracy of the classification results was within acceptable ranges, ranging from 77 to 78%. The study further revealed a continuing decline in wetlands extent and sparse vegetation, with average rates of 19% and 44%, respectively. Conversely, shrublands, croplands, and tree cover showed an increase, with average rates of 0.4% and 12.4% respectively. A significant finding was the replacement of a substantial portion (40%) of wetland areas with built-up areas, indicating that urban expansion is a major driver of wetland shrinkage in the study area. These results provide valuable insights into the declining extent of wetlands in the LTRB. Such findings are crucial for environmental management efforts, as they provide information on which wetlands should be prioritized when implementing strategies to prevent the negative impacts of LULC changes on wetlands in the area. Therefore, contributing towards achieving sustainable development goals relating to freshwater ecosystems protection and management.

Predicting priority management areas for land use/cover change in the transboundary Okavango basin based on machine learning

Remote sensing and modelling of land use/land cover (LULC) change is useful to reveal the extent and spatial patterns of landscape changes at various environments and scales. Predicting susceptibility to LULC change is crucial for policy formulation and land management. However, the use of machine learning (ML) for modelling LULC change is limited. This study modelled LULC change susceptibility in the Okavango basin using ML techniques. Areas with high LULC change susceptibility are termed priority management areas (PMAs) in this study. Trajectories of LULC change between 1996 and 2020 are derived from existing LULC change maps of the Okavango basin. Overlay analysis is then used to detect patches of LULC change transitions. Three LULC transitional categories are adopted for modelling PMAs, namely 1) from natural to anthropogenic classes (Category A); 2) from anthropogenic to natural classes (Category B); and 3) from natural to another natural class (Category C). An ensemble of ML algorithms is calibrated with categories of LULC change and social-ecological drivers of change to produce maps showing the susceptibility of LULC change in the basin. Thereafter, thresholding is done on probability maps of susceptibility to LULC change based on the maximum sum of sensitivity and specificity (max SSS) to delineate PMAs. Results for trajectories of LULC change indicate that anthropogenic activities (croplands, built-up areas, and barelands) generally expanded, displacing natural areas (wetlands, woodlands, water, and shrubland) from 1996 to 2020. Regarding PMAs, anthropogenic-related PMAs (Category A ∼34 560 km2) covered a larger area compared to the natural ones (Categories B∼33 407 km2) and (Categories C∼15 040 km2). The findings of this study emphasize the value of ensemble ML modelling in identifying PMAs and guiding transboundary land use planning. Overall, this study highlights the role of anthropogenic activities in driving land use changes in Transboundary Drainage Basins (TDBs) and suggests a need to promote sustainable practices in predicted PMAs through comprehensive planning to ensure water availability in the Okavango basin.

Open-access remote sensing data for cooperation in transboundary water management

ABSTRACT Open-access remote sensing products provide data for transboundary water management. This study presents a comprehensive overview of the applications, uncertainties and implications of these remote sensing data products in the context of transboundary water management. Focusing on different stages within the transboundary cooperation continuum, we delineate the potential role and application of remote sensing data at the various stages of this cooperation. Despite the uncertainties and capacity requirements for data acquisition, processing and interpretation, we argue that remote sensing broadens opportunities to monitor, assess, forecast, track or validate compliance in transboundary basins, thereby challenging traditional notions of water data exclusivity.

Painted Water—A Concept to Shape Water Negotiation Strategies in Shared River Basins

In a transboundary river basin, downstream states frequently express concerns regarding the potential utilization of water resources by upstream states as a tool for exerting coercion. This fact contributes to instilling doubt in the applicability of negotiations, even in transboundary basins that possess strong international agreements. In an effort to address the issue, this paper introduces the painted water concept. It divides upstream states’ available water into three triage color volumes before reaching downstream states in ascending order of negotiability: green, yellow, and red. Additionally, downstream states must consider the dynamics of transitions of painted water classes over time when developing their negotiation strategies and water policies. In order to assess the concept’s contribution in practice, we analyze trilateral riparian negotiations along the Blue Nile River basin, based on a “what-if” analysis approach under four global future scenarios. These results could shed light on part of the complexity of the Blue Nile negotiation and mainstream the water policies and perspectives of riparian states. Here, this paper shows that the painted water concept can provide multidisciplinary insights into proactive water negotiations. The inclusion of such a concept can help to deepen theories, approaches principals, and any disciplines pertinent to transboundary water negotiations.

Widespread increases in soluble phosphorus concentrations in streams across the transboundary Great Lakes Basin

Widespread increases in soluble phosphorus concentrations in streams across the transboundary Great Lakes Basin

Exploring neotectonic activity in a semiarid basin: a case study of the Ain Zerga watershed

AbstractMediterranean basin exposed to ongoing processes of erosion and deformation. Neotectonics is the study of the geological processes involved in the deformation of the Earth’s crust. The topography of the terrain is greatly impacted by these neotectonic events, which has a considerable impact on the drainage pattern and general geomorphology of the region. In this work, the active tectonics were evaluated using the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) and several Geomorphic Indices in the Ain Zerga region of Northeast Algeria. Asymmetry factor, basin form, the ratio of valley floor width to valley height, the sinuosity of mountain fronts, hypsometric integral, hypsometric curve, and transverse topographic symmetry factor were some of the indices used. These findings emphasize the tremendous tectonic activity that exists in the study area. In comparison to sub-watershed N°2, sub-watersheds N°1, N°3, and N°4 had stronger tectonic activity, according to the examination of these geomorphic indicators. The Relative Tectonic Activity Index (Iat) distribution pattern, which concurred with other pieces of information such as stream deflection and lineament analysis, corroborated these conclusions. We were able to learn a lot about the different levels of tectonic activity in the sub-watersheds by using traditional geomorphic indices. The tectonic activity-exhibiting basins consistently displayed connections with structural disturbances, basin geometry, and field research. Geomorphic indices and morphometric characteristics were used to identify tectonically active zones in a portion of the Mellegue transboundary basin, which shows a considerable influence of neotectonic activity in a portion of the Neogene basin.

Hydrochemical and isotopic evaluation of groundwater and river water in the transboundary Silala River watershed

AbstractThis article reviews a hydro‐chemical and isotopic study aiming to provide information about groundwater‐surface water interactions in the Silala River, a transboundary basin shared between Chile and Bolivia. The chemical and isotopic data show: The springs located in the northern section of the lower course of the Silala River and the Cajones springs in Bolivia have similar characteristics and represent a shallow flow system fed by local recharge. In contrast, the springs located in the higher and southern sections of the lower course of the river have similar characteristics than the Orientales springs located in the higher part of river basin indicating these springs are associated with a high‐altitude recharge area. The river in the upper course in Chile has similar chemical and isotopic characteristics to the springs already mentioned, indicating most of the river flow comes from the high part of the basin in Bolivia. The groundwater shows different chemical characteristics, similar depleted isotopic values, and much lower 14C values (including Orientales groundwater) than the upper springs and river, providing the first evidence that both systems are not connected in the Chilean section of the river and the springs system is part of a perched aquifer confirmed by visual field observations. These data support a conceptual model which includes an interaction between a perched aquifer, probably in alluvial deposits on the flanks of the volcanoes, and the river as result of a complex system of fractures present in the near‐surface levels of Silala Ignimbrite. This study provides valuable information for modeling of hydrological and hydrogeological data in the study area.This article is categorized under: Science of Water > Hydrological Processes Science of Water > Water Quality

Quantitative water balance of surface waters for a transboundary basin in South America

Quantitative water balance of surface waters for a transboundary basin in South America

Transboundary Nile basin dynamics: Land use change, drivers, and hydrological impacts under socioeconomic pathways

Landscape transitions in the Nile River basin will likely accelerate over the next decades due to socioeconomic developments and climate change. However, the assessments of land use/land cover (LULC) changes and their impact on the water resources over the Nile basin lacked a transboundary perspective. Here we used coupled basin-scale geospatial-hydrological models to project future LULC changes in the Nile basin and its three tributaries (i.e., White Nile, Blue Nile, and Atbara River), explored their drivers and projected hydrological impacts under different shared socioeconomic pathways (SSPs) during 2020–2060. Compared to 1992–2019, significant increases in the forested area (>50 × 103 km2) are expected to occur in the upstream areas of the White Nile and the Blue Nile in South Sudan and Ethiopia, with larger increases projected under higher emission scenarios. Consequently, it will likely reduce the downstream seasonal river discharge for the White and Blue Nile by up to 8.4% (SSP5) and 8.9% (SSP2), respectively. An increase of 7.4% in the Blue Nile discharge is expected during the flood season if the current urbanization/deforestation rates would prevail in the future. Large decreases (>15 × 103 km2) of unused land are expected in the Atbara River sub-catchment with increases in natural vegetation socioeconomic-related LULC types, leading to a river flow decrease of 15% during the rainy season under the SSPs. The basin-scale LULC changes are projected to decrease the Main Nile flow to Egypt by 3.6% under SSPs and increase by 2.1% if the historical trends prevail. The results highlight a close association between landscape dynamics, socioeconomic growth, and climate change over the Nile basin and suggest adaptive LULC planning and conservation measures.

A synthesis of hydroclimatic, ecological, and socioeconomic data for transdisciplinary research in the Mekong

The Mekong River basin (MRB) is a transboundary basin that supports livelihoods of over 70 million inhabitants and diverse terrestrial-aquatic ecosystems. This critical lifeline for people and ecosystems is under transformation due to climatic stressors and human activities (e.g., land use change and dam construction). Thus, there is an urgent need to better understand the changing hydrological and ecological systems in the MRB and develop improved adaptation strategies. This, however, is hampered partly by lack of sufficient, reliable, and accessible observational data across the basin. Here, we fill this long-standing gap for MRB by synthesizing climate, hydrological, ecological, and socioeconomic data from various disparate sources. The data— including groundwater records digitized from the literature—provide crucial insights into surface water systems, groundwater dynamics, land use patterns, and socioeconomic changes. The analyses presented also shed light on uncertainties associated with various datasets and the most appropriate choices. These datasets are expected to advance socio-hydrological research and inform science-based management decisions and policymaking for sustainable food-energy-water, livelihood, and ecological systems in the MRB.

Exploring “big picture” scenarios for resilience in social–ecological systems: transdisciplinary cross-impact balances modeling in the Red River Basin

Climate change is increasing the frequency and the severity of extreme events in river basins around the world. Efforts to build resilience to these impacts are complicated by the social–ecological interactions, cross-scale feedbacks, and diverse actor interests that influence the dynamics of change in social–ecological systems (SESs). In this study, we aimed to explore big-picture scenarios of a river basin under climate change by characterizing future change as emergent from interactions between diverse efforts to build resilience and a complex, cross-scale SES. To do so, we facilitated a transdisciplinary scenario modeling process structured by the cross-impact balances (CIB) method, a semi-quantitative method that applies systems theory to generate internally consistent narrative scenarios from a network of interacting drivers of change. Thus, we also aimed to explore the potential for the CIB method to surface diverse perspectives and drivers of change in SESs. We situated this process in the Red River Basin, a transboundary basin shared by the United States and Canada where significant natural climatic variability is worsened by climate change. The process generated 15 interacting drivers ranging from agricultural markets to ecological integrity, generating eight consistent scenarios that are robust to model uncertainty. The scenario analysis and the debrief workshop reveal important insights, including the transformative changes required to achieve desirable outcomes and the cornerstone role of Indigenous water rights. In sum, our analysis surfaced significant complexities surrounding efforts to build resilience and affirmed the potential for the CIB method to generate unique insights about the trajectory of SESs.