Estimate river flow standards to set climate change goals

Estimate river flows to set climate change mitigation goals

By Lydia Alvanou, Axios – Loudias – Aliakmonas Management Authority

The Protected Area of Axios-Loudias-Aliakmonas is an extended coastal wetland covering an area of 33.800 ha. The Axios delta Management Authority identified that impending climate change will add to and magnify pressures and risks that are already present in the watershed (e.g. irrigation, dams, or extractive uses) through its potential to alter rainfall, temperature, runoff patterns and to disrupt biological communities. It therefore commissioned a study on the ecological flow in Axios and Aliakmonas rivers to the Greek Biotope/Wetland Centre (EKBY).

The study applied the Instream Flow Incremental Methodology (IFIM). As a first step, target species of the rivers’ fauna and flora (fish, aquatic plants) were identified and their needs were accessed in terms of flow parameters (e.g. depth, velocity etc.). Furthermore, habitat suitability criteria curves for the above species were developed to assess the impact of alterations of flow regime on the availability of their habitat. The flow parameters (depth and velocity) under the different discharge scenarios in the two rivers were assessed by applying the hydraulic models of the two rivers that were developed and calibrated for this purpose. Finally, the minimum ecological flow for each river was proposed in such a way as to ensure maximum usable habitat area for target species:

Aliakmonas river May-June: ≥ 15 m3/s August-September: 20 m3/s .

Axios river May/June: 20 m3/s August/September: 30 m3/s (± 5 m3/s) .

The estimated flow standards will be incorporated into the National Park Designation Presidential Act that is currently being prepared.

Photo: Wet meadows in the Axios river © Lia Papadranga