[Published by the UdL Press Service]: Minimize the environmental impact of hydroelectric power plants on mountain river ecosystems by determining the role of sediments and the morphology of the channel in the effects of the sudden rises and falls of flow. This is the proposal of researchers from the RIUS Research Group of the Department of the Environment and Soil Sciences of the University of Lleida (UdL) in an article published in the journal Environmental Research Letters. It is signed with other scientists from the universities of the Balearic Islands, Bologna (Italy), Canterbury (New Zealand), Ottawa (Canada), Utah (USA) and the Malaysia campus of the University of Nottingham, in addition to the Division of Environment and Parks of the Government of Alberta (Canada). The aim is to design optimal ways to release water from the dams that use this system of hydroponks and at the same time establish possible actions for conditioning the channels that limit the impacts on their structure and composition, as well as the operation of the natural aquatic communities.

"Hydraulic energy is considered a form of renewable and green production, but generating electricity from rivers is not free to cause impacts on the environment," explains the professor of Physical Geography at the UdL and associate researcher at the Institute Catalan Water Research, Ramon J. Batalla. Power plants operating under a hydropower regime generate rapid and marked fluctuations in downstream river flows, when turbines come into operation to produce energy as demand marks. These hydropics, frequent and more visible in mountain rivers, can generate changes in the river ecosystem and biota downstream.

"The extensive existing casuistry indicates that it must be studied on a case-by-case basis. However, with regard to macro-invertebrates living at the bottom of the river, the sudden and rapid increase in flow can lead to a greater drag of individuals downstream, detaching them from the surface of the channel due to the mobility of the sediments that make it up or given the hydraulic force of the water.As for fish communities, changes in flow modify their habitat and a sudden drop in water level can trap them in side areas of the river, preventing them from moving and in some cases causing death if they run out of water, ”Batalla specifies.
 
Global demand for renewable energy is rising rapidly as fossil fuels need to be phased out, "so rivers are expected to continue to experience the effects of hydroelectric generation over the coming decades," he warns. Professor Ramon Batalla. Its aim is to find forms of hydraulic energy production that limit the effects on downstream river ecosystems and propose mitigation or improvement measures, in line with the requirements of the European Union's water framework directive.
 
The researcher also indicates that "the analysis of hydroponics and their impacts and mitigation represent a current scientific and environmental management challenge of the first order." Therefore, “it is necessary to place it in a broader context, both in relation to the transition to carbon-free forms of energy production, and to the multiple uses of water, and to the functions and services of the associated aquatic ecosystems, ”he adds.
 
The article published in Environmental Research Letters advocates studying the morphology of riverbeds and their sediments "as a critical causal link between flow regimes with hydrofoils and the ecological changes observed in rivers affected by this activity." Using multiple data acquisition tools (remote sensing, geomatics) and modeling, researchers can characterize in detail changes in riverbed configuration, topography, and sedimentology. "We can quantify processes from centimeter to kilometer scales and this is important to quantify the intensity of impacts and the variation in space and time," says Batalla.

UdL researchers began their studies on the environmental effects of hydroelectric power plants in 2010, in La Noguera Pallaresa, with the institutional support of the Ebro Hydrographic Confederation and the Catalan Agency of the Water, and the collaboration of the electricity companies Endesa and Acciona. A research that has continued through projects of the National R & D & I Plan MorphPeak (CGL2016-78874-R) and MorphHab (PID2019-104979RBI00) funded by the Ministry of Science and Innovation, and the European ERDF funds, and with the support of the Generalitat de Catalunya through the RIUS River Dynamics Research Group SGR2017-0459. They are also part of the European Hypeak Network, which became operational in 2020 and of which they are founding members.