After the climatological and current situation are realized, the autonomous scenario and other scenarios can be developed according to the DPSIR method to make sure the right relations are used in a transparent and structured way. The comparison of the different simulations (climatological, autonomous, scenarios) is compared to the current situation run (Figure 1). This comparison shows how E-Flows have changed due to for example dams and water abstraction (climatological simulation) and how E-Flows may change due to autonomous developments and intended strategies. A first comparison between the climatological situation and current state may already give a valuable first impression of what drivers and pressures control the fluvial system. However, if there is no information on human interventions, scenarios and strategies can be compared to the climatological run.
Figure 1: relative comparisons between the current state (current management) and different simulations
REACT has three levels of comparison between scenarios and strategies. Level 1 is the most abstract level and compares how, for example, the creation of dams changes some typical fluvial conditions, like mean flow velocity or peaks in discharge during a certain period. Those changes are expressed on a map (Figure 2).
Figure 2: example of mean annual flow velocity in a river with three zones. Left the situation without dams and right with dams. Dams are indicated with orange lines.
The second level of comparison is focused on trait strategy per biological group (macrophytes, fish, etc). The results are presented spatially on maps and in tables. On maps the comparison can be done by visual comparison (Figure 3), but also maps can be made that show the difference between two simulations. The comparison in tables (Table 1) indicates whether changes in trait strategy are positive (‘home’ to the trait strategy) or negative (‘invasive’).
Figure 3: example of fish guild composition in three FZPs without dams (left) and with dams (right). Dams are indicated with orange lines.
Table 1: conceptual table to indicate whether a change in trait strategy is desirable. Results are on FPZ level.
The third and most detailed level of comparison is the analyses of what filters (states) limit the occurrence of trait strategies and how this may differ between scenarios. Moreover, these types of analyses are valuable to indicate the main drivers and pressures governing the state of the fluvial system. This helps to design and refine strategies to mitigate the pressures and create the right conditions for the occurrence of the desired trait strategies.
