The volume of research on transboundary rivers and their management in the Global South is disproportionately small when compared to the size of the river basin populations, water withdrawals, and consumption in these regions. This disparity is evident from an extensive analysis of 4,713 case studies, which was conducted using machine learning techniques and a desk review. Transboundary river basins (TRBs) are crucial resources for millions of people, but they are facing significant anthropogenic pressures, hydro-political tensions, and the escalating impacts of climate change. These challenges call for collaborative research that crosses multiple disciplines, sectors, and national borders to address shared water management goals and contribute to achieving the United Nations' Sustainable Development Goals (SDGs).

The study aimed to achieve three main objectives: (1) to understand the themes, patterns, and perspectives in transboundary river-related research, (2) to assess the disparities in research between the Global North and Global South, and (3) to propose a sustainable management approach for transboundary river basins worldwide. To achieve these goals, the study utilized machine learning models to analyze 4,237 publications, in addition to conducting a desk review of 327 relevant articles. The analysis resulted in the thematic categorization of 4,732 case studies, which provided a comprehensive global perspective on the prospects for sustainable management across 286 transboundary river basins worldwide.

Transboundary rivers are critical to global sustainability. According to previous research, these river basins support 52% of the world’s population, contribute 60% of the total global freshwater flow, and span 47% of the Earth’s land surface. Despite their importance, these river basins face a range of challenges, including hydro-political disputes, pollution, water-sharing conflicts, natural hazards, climate change impacts, and ecosystem vulnerability. Notable river systems that have been at the center of transboundary water conflicts include the Mekong, Indus, Nile, Ganges-Brahmaputra-Meghna (GBM), Mississippi, Colorado, Rhine, and Danube rivers. Countries such as India, Bangladesh, Pakistan, China, Ethiopia, Sudan, Egypt, and others are frequently involved in transboundary water disputes. These conflicts are often exacerbated by competing demands for water for agriculture, hydropower, and domestic use.

A key finding of this research highlights significant variation in the volume of studies conducted on different transboundary river basins. For instance, the Mekong River accounts for 18.8% of studies, the Indus River for 15.5%, and the Nile River for 11.9%. The distribution of research is far from equitable, with the majority of studies focusing on large river basins in the Global North, while smaller and medium-sized river basins, particularly in the Global South, remain under-studied. This contrasts sharply with the smaller number of studies conducted on river basins in the Global South, where water security and resource management issues are more pressing.

Furthermore, there is a noticeable regional variation in the types of research conducted on transboundary rivers. In Asia, which accounts for 43.7% of the total transboundary river research, the focus has largely been on hydro-political conflicts, particularly in large river basins such as the Mekong, GBM, and Indus. These research efforts are driven by the complex geopolitical dynamics in these regions, which have often led to tensions and disputes over water resources. such as the Nile, Indus, and Mekong rivers, are frequently studied due to their geopolitical importance and water governance related conflicts. In contrast, smaller river basins in Asia, which face severe water crises and have dense populations, have received far less attention. This regional disparity is not limited to Asia; Africa also faces similar challenges. Research in Africa has been concentrated on the impacts of climate change, natural hazards, and water-sharing conflicts, particularly in river basins like the Nile. The socio-political challenges and limited research infrastructure in many African countries have hindered comprehensive studies on sustainable water management in these regions.

In North America, research on transboundary rivers has focused heavily on large river basins, which account for 28.31% of the total research in the region. Similarly, Europe has also concentrated its research on medium-sized river basins, which constitute 36.9% of its transboundary river studies. In both North America and Europe, much of the research has centered on issues such as climate change, disaster management, and water governance. Interestingly, despite the large-scale water crises in Asia, it has the least number of studies on small river basins, a gap that is particularly concerning given the increasing water scarcity challenges in this region.

Thematic analysis of the transboundary river research revealed key areas of focus. Hydropolitics, which accounted for 15.6% of the total research, was the most prominent theme, with studies primarily addressing conflicts, cooperation, and water-sharing agreements in large river basins. Other significant themes included landscape ecology, pollution, governance and policy frameworks, climate change, disaster management, and ecosystem vulnerability. While large river basins have dominated the research agenda, small and medium-sized river basins, which face acute water crises and socio-economic challenges, have been overlooked.

Fig 1. Network of corresponding institutions and its relationship with co-authors; The contributions from global south scholars and those from downstream countries are minimal compared to those from the global north and upstream countries. 

One of the notable trends in the research is the varying emphasis on governance-related issues in different regions. The advanced infrastructure and institutional frameworks in the Global North have led to greater attention on landscape ecology, technical aspects of river management, and policy issues related to governance. In contrast, the Global South has focused more on hydro-political conflicts, resource competition, and the challenges posed by local capacity constraints. This regional difference in research focus highlights the need for a more inclusive approach to water governance that incorporates local knowledge and addresses the specific needs of countries in the Global South. The Global South also faces challenges related to inadequate research infrastructure, which limits the scope of studies that can be conducted on transboundary river basins in these regions.

A major focus of transboundary river research has been on large river basins with high rates of runoff. The primary research themes in these areas have been related to dam construction, cooperation, water-sharing agreements, and the management of water resources between upstream and downstream regions. Examples of such river basins include the GBM, Mekong, Blue Nile, and Indus Rivers. These rivers have been the focus of numerous studies exploring how countries can manage water resources equitably, particularly in the face of rising water demands and geopolitical tensions.

International organizations such as the United Nations Economic Commission for Europe (UNECE), the Transboundary Waters Assessment Programme (TWAP), and the United Nations have developed several frameworks and guidelines to promote transboundary water cooperation. These initiatives emphasize the need for equitable water management, conflict resolution, and integrated basin management, which are essential for achieving the SDGs. The adoption of these guidelines could help promote sustainable management practices in river basins around the world. The study also highlighted significant gaps in research, particularly in small and medium-sized river basins, which are often overlooked in favor of larger, more politically significant basins. There is a need for greater focus on these smaller rivers, which are vital for local communities and often face the most severe water security challenges. Sustainable management of these smaller basins requires innovative solutions that take into account the unique ecological, social, and economic conditions in each region.

In conclusion, the study revealed substantial disparities in transboundary river research between the Global North and Global South (Fig1). While the Global North has the infrastructure and research capacity to address complex governance and ecological issues, the Global South faces significant challenges related to hydro-political conflicts, resource management, and research capacity. To address these disparities, there is a need for more research on small and medium-sized river basins, with an emphasis on local capacity building, governance reforms, and international collaboration. By focusing on these areas, researchers and policymakers can work together to promote sustainable management of transboundary rivers and contribute to the achievement of the SDGs. Our findings recommend fostering equitable, inclusive research in transboundary river basins, particularly in the global south. This involves empowering local researchers, enhancing science diplomacy, and increasing funding for underrepresented regions. Collaborative North-South partnerships should prioritize addressing socio-economic, cultural, and geopolitical complexities while bridging critical knowledge gaps in these vital areas.