Design of a Biological Corridor for Migration of Freshwater Prawn over a Dam in the Southwestern Slopes of Los Andes, Peru

Andrés Goyburo; Jesús A. Mejía; Aníbal S. Verástegui
Faced with the effects of climate change, forms of environmentally friendly energy production, such as hydroelectric plants, are promoted. However, the building of these structures in a riverbed represents an obstacle to the movement of migratory aquatic species. A new case involves rivers of southwestern slopes of Los Andes, inhabited by crustaceans with economic and environmental importance. Considering the proposed construction of a diversion dam for a hydroelectric plant on the Ocoña River, 120 km upstream from its mouth, from 8 sampling points, the freshwater prawn (Cryphiops caementarius) population and its corresponding intensity of migration were estimated. The results were used to make hydraulic calculations, the sizing of passage for migrating species and for hydraulic modeling using HEC-RAS software. From the collection and analysis of the samples, it was found that the population is distributed depending on altitude. The intensity of migration was found between 0.88-23.67 and 4.02-34.92 prawns.min-1 for wet and dry season respectively. The average migration intensity was 10.08 prawns. min-1. It was calculated the ratio of required space/total length specie in 0.83, equivalent to a surface density of 1.35 migrating prawns per square meters. Considering an area of 4.80 m2 and the referred migration density, it was determined for each square meter a migration rate of 6.48 prawns. min-1. The biological corridor width results in 1.56 m, and an operating water flow of 0.33 m3. s-1. The population composition and the ability of this specie to climb over surfaces, out of the water, indicated that the most suitable step is the type pool - weir. In conclusion, the work allowed defining the architecture and dimensioning of the migration passage, according to specific requirements of the specie.
Cryphiops Caementarius; Freshwater Prawn; Migration; Fish Passage; Ecohydraulics; Hec-Ras
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