Transboundary rivers and seas play a critical role in global stability, providing essential resources such as water, energy, and food security. Yet they are also flashpoints for international conflict. With over 260 international river basins and numerous shared seas, disputes often arise over usage rights, ecological protection, and access. The legal frameworks that govern these shared waters attempt to balance sovereign interests with the broader needs of basin or maritime communities. However, climate change, rapid development, and shifting geopolitics have made existing legal instruments increasingly inadequate.

International Legal Frameworks for Shared Waters

1. The UN Watercourses Convention (1997)
   This Convention provides foundational principles such as equitable and reasonable utilization, no significant harm, and the duty to notify and consult in planned developments. Though not universally ratified, it is regarded as reflective of customary international law.
    
2. The UNECE Water Convention (1992)
   Originally for European states, it was opened globally in 2016. It emphasizes basin-level cooperation, joint monitoring, and dispute resolution.
    
3. The United Nations Convention on the Law of the Sea (UNCLOS, 1982)
   UNCLOS regulates maritime boundaries, navigation, and marine resource exploitation. It applies to the mouths of rivers, estuaries, and semi-enclosed seas, often intersecting with inland water disputes.
    
4. Customary International Law and Regional Agreements
   Customary law, bilateral treaties, and regional agreements often take precedence in specific cases where global conventions do not apply or lack enforcement.
    

Case Studies of River Disputes

1. The Indus Waters Treaty and Kishanganga Dispute (India–Pakistan)
   The Indus Waters Treaty of 1960, brokered by the World Bank, divides the six rivers of the Indus system between India and Pakistan. The Kishanganga Hydroelectric Project led to arbitration by the PCA in 2013, where India was permitted to build the dam but required to maintain downstream flows. In 2024, Pakistan initiated new arbitration concerning planned Indian dams on the Chenab River.
    
2. Gabčíkovo–Nagymaros Project (Hungary–Slovakia)
   Hungary halted its part of a dam project citing environmental harm. The 1997 ICJ ruling held both parties responsible but urged updated agreements to reflect evolving environmental norms.
    
3. The Silala River Dispute (Chile–Bolivia)
   In 2022, the ICJ ruled that the Silala River is an international watercourse subject to shared usage rights, despite Bolivia's claim it was artificially diverted.
    
4. Grand Ethiopian Renaissance Dam (Ethiopia–Egypt–Sudan)
   The GERD project has become Africa's most contentious water dispute. Ethiopia completed its fourth filling in 2024. Egypt insists on a binding treaty, fearing existential threats. Negotiations remain deadlocked despite AU mediation.
    

Maritime and Semi-Maritime Disputes

1. The Mekong River and China's Role
   China controls the upstream portion of the Mekong but is not part of the Mekong River Commission. Its dams have caused drastic downstream shortages. As of early 2025, the MRC reports record-low flows affecting Cambodia and Vietnam.
    
2. The South China Sea Disputes
   The PCA ruled in 2016 against China's territorial claims, favoring the Philippines. However, China ignored the verdict. In 2024, the Philippines announced another PCA case over environmental harm and harassment of its fishermen.
    

The Role of Climate Change

Climate change is redefining legal responsibilities in water governance. Melting glaciers are altering river flows; rising seas threaten to submerge baselines under UNCLOS. In 2024, the UN began debating whether maritime boundaries should remain fixed despite changing coastlines. Low-lying nations advocate for "legal stability" of their Exclusive Economic Zones.
 

Proposed Solutions to Transboundary Water Disputes

1. Establishing Binding Multilateral Agreements
   Countries sharing rivers or seas must create enforceable treaties with dispute resolution mechanisms. Regional bodies should be empowered to facilitate this. For example, China should be encouraged to join the MRC or form a parallel legal structure.
    
2. Enhancing the Role of International Courts
   The ICJ, PCA, and regional courts should be used more proactively. Their judgments should carry enforcement mechanisms, possibly through UN Security Council backing, especially in maritime disputes.
    
3. Incorporating Climate Science in Legal Instruments
   Agreements should be updated to reflect hydrological shifts and environmental risks due to climate change. This includes guaranteeing minimum environmental flows and adapting treaty baselines.
    
4. Transparency and Data-Sharing Mechanisms
   Unilateral decisions often stem from a lack of transparency. Legal mandates for real-time data sharing, such as between India and Pakistan or China and the Mekong countries, could prevent misunderstandings.
    
5. Promoting Regional Legal Forums
   Legal bodies such as the African Court of Justice or ASEAN legal mechanisms should be empowered to mediate and adjudicate river or sea disputes.
    
6. Capacity Building and Civil Society Involvement
   Support from civil society, local communities, and NGOs can ensure compliance and promote ecological awareness. Community-based water diplomacy has succeeded in parts of the Nile and Mekong regions.

Conclusion
Shared rivers and seas represent both an opportunity and a threat. International law provides the tools to manage these resources, but only if states respect the rule of law and prioritize collective sustainability over narrow nationalism. The future of peace in many regions may depend less on military power and more on the fair sharing of water. As disputes grow more complex under the pressures of development and climate, legal innovation and cooperative diplomacy will be the cornerstones of survival.

References:

• United Nations Convention on the Law of Non-Navigational Uses of International Watercourses, 1997
  URL: https://treaties.un.org/doc/Treaties/1997/05/19970521%2006-03%20PM/Ch_XXVII_12.pdf
• Gabčíkovo–Nagymaros Project (Hungary/Slovakia), ICJ Judgment, 1997
  URL: https://www.icj-cij.org/public/files/case-related/92/092-19970925-JUD-01-00-EN.pdf
• Kishanganga Arbitration (India v. Pakistan), PCA Award, 2013
  URL: https://pcacases.com/web/sendAttach/67
• ICJ, Silala River Dispute (Chile v. Bolivia), Judgment, 2022
  URL: https://www.icj-cij.org/public/files/case-related/162/162-20221201-JUD-01-00-EN.pdf
• Al Jazeera, "Ethiopia completes fourth filling of GERD dam," September 2024
  URL: https://www.aljazeera.com/news/2024/9/10/ethiopia-completes-fourth-filling-of-gerd-dam
• Financial Times, "Philippines plans new South China Sea legal challenge," October 2024
  URL: https://www.ft.com/content/philippines-new-south-china-sea-legal-challenge