Vision / Society and communities / How a river scientist resolved a 150-year-old border dispute

Society and communities

How a river scientist resolved a 150-year-old border dispute

Costa Rica is home to an abundance of wildlife, with protected rainforests and wetlands that make it one of the most biodiverse countries in the world. But when a territorial dispute threatened the safety of endangered species, Costa Rica took its case all the way to the International Court of Justice – calling on Professor Colin Thorne as a key witness.

The Central American country’s border dispute with neighbouring Nicaragua dated back to 1858, souring relations between the two nations for more than a century and a half and periodically flaring into armed conflict. It flared up again in 2010 when Nicaragua’s army occupied part of Costa Rica and oversaw work intended to change the course of the Rio San Juan, which marks the border.

There was no question of Costa Rica regaining control of the occupied territory by force because Nicaragua has a well-equipped army, while Costa Rica has only border police, having disbanded its army in 1947.

The country’s only recourse was to rely on international law as adjudicated by the UN-backed International Court of Justice (ICJ).

Professor Thorne, of the School of Geography, said: “Events that provoked Costa Rica to open a case against Nicaragua in the ICJ were not disputed. Nicaragua excavated a canal linking the Rio San Juan – which is under Nicaragua’s sovereignty – with a coastal water body called the Harbor Head Lagoon, which is also Nicaraguan territory. The case focused on whether that canal ran through Costa Rican territory or not.”

In framing their arguments, the legal teams of both countries called on internationally renowned river experts from leading universities to help them and the judges unravel the complex history of changes in the physical geography of the largest river in Central America.

"Costa Rica vs Nicaragua demonstrated that it is possible for a nation to protect its sovereign territory through recourse to the rule of law, rather than by force of arms."
Professor Colin Thorne

Costa Rica chose Professor Thorne, who composed a scientific research programme to build the evidence base necessary to inform the court on cartographic, fluvial and environmental issues underpinning the legality and impacts of Nicaragua and Costa Rica’s actions. He then led a team of Costa Rican technical specialists in collecting and collating technical and scientific data, carried out fieldwork and presented all the evidence to the court.

After a lengthy legal process, the ICJ ruled that Nicaragua had violated Costa Rica’s territorial sovereignty by occupying land on the Costa Rican side of the river. Such was the severity of the environmental harm, which involved clearing several hectares of rainforest and excavating wetlands protected under international convention, that for the first time in its history the court imposed damages on the offending nation.

Nicaragua accepted the Court’s rulings against it and paid $378,000 in damages to Costa Rica.

Professor Thorne said: “All nations stand to benefit from the court ruling – for the first time in history – of the award for damages for environmental harm, because this will deter states from undertaking activities liable to cause environmental harm to another state.”

Other beneficiaries of the impact of Professor Thorne’s research are peaceful nations threatened by militarily aggressive neighbours.

Colin Thorne

Professor Colin Thorne is a river scientist with particular expertise in erosion, sediment transport and sedimentation. His educational background is in environmental sciences, civil engineering and physical geography; he also has skills in expert knowledge elicitation and qualitative assessment.

More impact case studies

A year on: working class women and work during the Covid-19 pandemic

Read More

An academic working in government: reflections from a Chief Scientific Adviser

Read More

Cities and communities after the pandemic

Read More