HydroEnv - Optimizing Environmental Flow Releases under Future Hydropower Operation

This project investigated the problem of monitoring, modelling and optimising environmental flow releases under future hydropower operation in Switzerland. HydroEnv is part of the SNF National Research Programme 70 project "Supply of Electricity for 2050: HydroPower and GeoEnergy". The objective of HydroEnv was to view the planned hydropower production increase in Switzerland in conjunction with a rise in possible environmental degradation in river systems downstream of dams and intakes. HydroEnv aimed to provide an integrated monitoring, modelling and assessment methodology by which impacts of current hydropower release rules can be quantified, operation strategies can be improved, and future environmentally conscious, societally acceptable, and economically viable flow release rules can be designed. The working group was composed of four PhD students at different institutions, each researching aspects of the methodology on study sites in the Maggia and Borgne rivers in Switzerland.

Project Partners: ETH Zurich, EAWAG, Uni Lausanne, EPF Lausanne
Duration: 1 February 2015 -- 31 January 2018

• Phd Project 1: Hydrological flows and stresses on riparian vegetation (ETH Zurich)
  This PhD project simulated runoff generation in hydropower affected watersheds with physically-based hydrological modelling approaches, developed inflow scenarios for operators, including state-of-the-art climate change projections. A 2d coupled surface-groundwater hydrodynamic modelling approach was implemented in the affected rivers downstream to study the effects of low and high flow dynamics on riparian vegetation. Water (both drought and flood) stress on riparian vegetation was monitored with field measurements and remote sensing to provide ground verification.
  Supervisors: Prof. P. Burlando, Prof. P. Molnar

• PhD Project 2: Monitoring river ecology and flow disturbance (EAWAG, Duebendorf)
  This PhD project determined temporal response patterns of macroinvertebrates, periphyton and sediment metabolism in the river reaches affected by regulation. State-of-the-art drone technology and river surveying were used to map sediment distribution patterns. Sediment respiration was quantified for different floodplain compartments (e.g. gravel bars, riparian areas, instream sediments, floodplain islands) for an ecosystem assessment of floodplain metabolism along the entire river system. The results were compared with data from other regulated rivers in Switzerland (e.g. Spöl).
  Supervisor: Dr. Christopher Robinson

• PhD Project 3: Sediment disruption and river morphology (Uni Lausanne)
  This PhD project quantified the degree of disruption in coarse sediment flux and associated ecosystem impacts which results from regulating flow and the consequences this has on sediment dynamics, river morphology and hence instream ecology over short and long timescales. High precision elevation models derived by drone survey and laser scanning were used to quantify erosion and deposition patterns along the affected river reaches. The effects on instream habitat was assessed with novel methods which take into account the ecological uncertainty associated with habitat modelling.
  Supervisor: Prof. Stuart Lane

• PhD Project 4: Establishment of dynamic environmental flows (EPF Lausanne)
  This PhD project developed an analytical and numerical framework on the basis of which dynamic flow redistribution policies which balance hydropower generation and riverine ecosystem needs can be quantified. The quantification was based on traditional ecohydrological indicators as well as new ecosystem measures from hydrodynamic modelling of affected river reaches. A particular focus was on studying operational policies to generate dynamic environmental flows, which mimic natural flow variability as opposed to constant minimum flows.
  Supervisor: Prof. Paola Perona