Sediment management in dams in the Andes

I visited Colombia, Ecuador, Peru, and Bolivia, with the purpose of learning about their dam projects, built and proposed ones. I aimed to learn about their vision, strategic plans, and environmental concerns in these topics. Particularly, I aimed to collect information for estimating sedimentation rates in dams. The Andes have one of the largest soil erosion rates in the world because of their high rainfall intensities and steep slopes. Therefore, sedimentation rates in reservoirs should be higher than the world average, which is 1%. There are plenty of dams built, in these four countries, because of their rivers with steep slopes and high discharges, which cascade down from the Andean Mountains, resulting in many potential sites for dams. Since the last decade, those countries have intensified their hydropower development. For example, by 2016, Bolivia only used 1.2% of its hydropower potential. By 2025, the country's plan to invest 25 billion dollars for building 35 hydropower projects will generate 11 GW. Ecuador has built more than 10 hydropower projects during the last 10 years and has a large project portfolio aiming that hydropower constitutes the 90% of the Ecuadorian energy source. Colombia has similar goals, by exploiting its hydropower potential in the Magdalena and Cauca Basins. While Peru deals with a problem of water resources distribution, as 97.5 % of the total surface water resources of the country are in the Amazon Basin, however, 65% of Peru’s inhabitants live in the basins that drain to the Pacific. Thus, they divert water from the Amazon tributaries. The total number of built dams in the four countries would surround 1,000, accounting for dams for irrigation, drinking water supply, flood control, and hydropower. Despite their different designs and locations, they share a common ground: Lack of Sediment Management. For example, Poechos, the largest reservoir in Peru, completed in 1997, has already lost half of its original capacity. Those projects are expensive, and when a reservoir is considered full of sediments, it not only lose its benefits, it also becomes a potential hazard and the dam should be removed. Dam removal costs are as high as 50% of the dam construction costs. During my trip, I primarily visited research groups focused on water resources, but not limited to engineering departments. I also contacted and visited governmental regulatory institutions, climate monitoring institutions, and I visited a few dam sites as well. Particularly in Ecuador, where I went to several rivers in the Ecuadorian Amazon. My next phase is to process and analyze the collected data. One expected result is strategic dam planning. It emphasizes the need for free-flowing rivers, without stopping developing. It shows the potential of hydropower, the amount of sediment trapped in dams, and which rivers are free-flowing. These countries have plenty of water resources, however, a diversification between hydropower generation together with additional renewable energy resources is more sustainable than maximizing only hydropower. In the case of the Amazon Basin, watershed management should be a priority over each country's plans, promoting electric interconnections between the countries.