SJE Ecohydraulic Engineering GmbH (SJE)

SJE Ecohydraulic Engineering GmbH focuses on the field of ecohydraulics.Ecohydraulics describes the relationships between hydraulics (e.g. water depth, flow velocity), water morphology (e.g. structures and bed substrates in water bodies) and water habitats.

Figure 1: Functional principle of simulation system CASiMiR.

Since 2001, SJE has been developing the CASiMiR habitat simulation system and using it in practice. The CASiMiR software can be used, for example, for the development of ecologically sound flow regimes for water withdrawals from water bodies. This aspect makes it an important tool for environmental impact assessment of power generation projects (hydropower, cooling water), but increasingly also for irrigation projects. Another field of application is the evaluation of measures in river construction and rehabilitation - already in the planning phase. This is because CASiMiR not only allows the investigation of implemented measures, but also the evaluation of planning scenarios in which river bathymetry, morphology and discharge can be varied and optimized.

Recent developments of CASiMiR include a transient module that can be used to study the effects of rapidly changing flow conditions (e.g., hydropeaking) on fish and invertebrates. In addition, a module is currently being developed and adapted to predict fish swimming paths, which can be used, for example, to optimize the location of fish ladder entrances and their guiding flow.

CASiMiR software offers the possibility to investigate important aspects of river ecology (habitats, connectivity, fish migration behavior) on the basis of high-resolution terrain models (e.g. from drone aerial surveys), flow calculations and preferences of aquatic organisms. The model, in contrast to most other methods, provides quantitative information on stream ecology, e.g.:

- the increase in area of potential spawning habitat with gravel additions and flow variation,

- the stranding risk for fish larvae in case of rapid flow reduction,

- the improvement in the detectability of fishway entrance with increasing discharge.

SJE uses CASiMiR software in a variety of water management projects worldwide and offers introductory courses in modeling.

Figure 2: Fish lift facility Runserau (Austria) (left); modeling to optimize position and dotation of fish lift entrances: flow velocity classes according to swimming ability of grayling and brown trout, starting fish positions and predicted swimming paths (right).

In addition to practice-related projects, SJE is active in research and cooperates with leading universities and research institutions. Examples are the work on fish-shaped sensors in the project "Fishview" within the BONUS program of the European Commission, on the environmental sustainability of hydropower plants, as well as on hydropeaking and fish migration in the EU-funded projects Hydro4U and FitHydro, and on the behavior of fish in front of turbine intake screens in the project MeMo funded by the German Federal Foundation for the Environment. As part of the EU-funded doctoral program RIBES, SJE supervises young scientists working on new approaches to describe and predict fish behavior in the vicinity of fishways.  The company is thus active at the important interface between science and practice, where new methods and techniques are transferred to practical applications. Practical experience is incorporated into the research work and the state of the art is constantly being redefined.