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Fishermen in Pijino, in the lowlands of the Magdalena River Basin. Flickr / Mauricio Montoya
A collaboration between SEI and The Nature Conservancy is using a WEAP model to analyse how dam construction could affect wetland ecosystems and flood risks downstream.
Hydropower is very important for Colombia – in the last decade, it has provided three-quarters of all electricity. With the economy growing by an average of 3.5% per year, the country needs to boost energy production, and there are plans to build several dozen new large and mid-sized hydropower dams.
From an energy perspective, the benefits are clear: 26 dams on the Magdalena River Basin, Colombia’s largest, already provide about 33,400 GWh of power per year, and two major plants under construction, plus 30 planned projects, would boost hydropower capacity in the basin by more than 160%.
But the Magdalena River is not just an energy source: it also feeds a natural treasure, the wetlands of the Mompos Depression. Annual large-scale inundation of the Mompos floodplains regulates water, nutrient and sediment cycles that sustain a rich biodiversity and crucial ecosystem services.
‘Hydropower by Design’
Aiming to ensure that hydropower development is sustainable and does not disrupt key ecosystems, The Nature Conservancy (TNC) has promoted a basin-wide integrated management and planning approach, “Hydropower by Design”. As part of this approach, TNC teamed up with SEI to build a model of the Magdalena River Basin using SEI’s Water Evaluation And Planning (WEAP) system.
“This is part of a broader project funded by USAID [the U.S. Agency for International Development] to develop tools to support adaptation to climate change in Colombia,” says Marisa Escobar, a senior scientist at SEI-US and leader of the USAID project.
“TNC was already studying the Magdalena basin, and they asked us for technical support to integrate WEAP with their concept of ELOHA (ecologic limits of hydrologic alteration), a process to identify conservation areas in the context of water systems management. USAID suggested that we work together to support sustainable hydropower development.”
Along with ecosystem impacts, the project team set out to study flood risks. The Mompos Depression is highly vulnerable to extreme floods, and in 2010–2013, a particularly wet “La Niña” led to severe floods that caused numerous deaths and widespread property damage in the lower Magdalena basin.
Since those floods, several studies have been conducted to identify ways to reduce flood risks, and some identified the development of hydropower dams as a potentially helpful measure. But those studies did not look at flood dynamics in the basin as a whole, nor did they fully consider climate change.
Macro-basin-level approach needed
“In general, water resources planning tends to take a local view,” Escobar says. “This happens in large river basins around the world, from California to Thailand, and it has grave consequences. What you need is a macro-basin-level approach that is detailed enough to understand each sub-basin, but also shows the cumulative effects of actions throughout the basin. Even though there was information about the Lower Magdalena, no one had analysed how actions upstream could affect the floodplains, integrating hydropower scenario development and ecosystem services.”
Initial results of the WEAP analysis show that hydropower dams could substantially reduce water flows during the dry months, and thus harm wetland ecosystems. But the dams would not protect lowland communities from extreme floods during periodic high flow events, because upstream reservoirs would have to release water for dam safety. “In fact, flood risks could increase, because the change in water flows might lead communities to develop land that is highly exposed to flooding,” Escobar says.
The Mompos Depression is surrounded by major coca growing regions and trafficking routes. Click to enlarge.
The Mompos Depression is hot and humid, and it is close to several cocaine-growing regions and trafficking routes, Escobar says. As the violence has subsided, development has accelerated, with a particular focus on agriculture (including oil palm) and livestock.
Escobar stresses that the goal of this project is not to stop hydropower development, but to identify key ecosystems to prioritize for conservation, and thus identify the most sustainable pathways for hydropower growth. “This study adds important new insights to inform decision-making in the region,” she says. “But a lot more work remains to be done.”
Building capacity with decision-makers
As part of the USAID project, SEI has worked with water resource planners and policy-makers across Colombia, building technical capacity and, at the same time, promoting a more holistic approach. “It’s hard for someone in Cali o Bogotá to imagine how their choices might affect wetlands in the Lower Magdalena, hundreds of kilometres away,” Escobar says. “But through our conversations, as well as field trips to California and its Sacramento-San Joaquin Delta, we have tried to highlight the importance of looking at the big picture to manage water resources sustainably.”
TNC is continuing its work on the Magdalena, and is also sharing the study results with national decision-makers. “SEI doesn’t have a permanent presence in Colombia, so our partnership with TNC is key if we want to inform national policy,” says Escobar. “We’ve worked mostly at the regional level, so we make a good team – they work at the national level, and we continue to raise awareness at the regional level, to ensure that local decisions are informed by a broader perspective.”
The wetlands in the Mompos Depression are home to a rich variety of species, including wading birds such as these wintering Great Egrets. Flickr / Mauricio Montoya