Monitoring in the LIFE IRIS Project
To better understand the effect of the measures in LIFE IRIS, a comprehensive monitoring programme is being carried out. A temporal comparison is made based on a pre-monitoring (assessing the status quo) and a post-monitoring (assessing the status after implementation of the measures).
What is biological monitoring?
Investigative work!
The idea behind biological monitoring is to use the presence of certain plants or animals at a location to draw conclusions about their habitat.
Many things that crawl, flit, flutter and swim in and around the water can help to assess the ecological condition of a water body.
By the way, it’s always worth turning over a stone or two in a shallow body of water to catch a glimpse of this wondrous world!
Aquatic ecologists therefore go in search of clues in the water: with protocols, cameras, special nets, measuring instruments or even power generators.
Electrofishing is particularly impressive. This method is used to catch fish without harming them. They are stunned for a short time using electricity, measured and released back into the water.
What is unique about LIFE IRIS monitoring?
7 IRIS indicators.
As the LIFE IRIS project considers various aspects such as aquatic ecology, ecosystem services and flood protection as a whole, it is important that these topics are also reflected in the monitoring. Based on a comprehensive monitoring concept (Csar & Gumpinger, 2020), the seven indicators to be used in LIFE IRIS were determined:
Hydromorphology
Hydromorphology refers to the shapes and structures of a water body, including gravel banks and bays or weirs and straightened sections. Hydromorphology also determines the flow behaviour and bed load.
Hydromorphology is the main indicator for measures in the bed and bank area, for the bed load balance and for the water regime. When analysing and evaluating measures, a very good significance is required for small-scale considerations.
Hydromorphology in the IRIS project:
Hydromorphology is assessed in LIFE IRIS using a specially tailored method that enables small-scale evaluation of the measures. As all measures aim to improve hydromorphology, this indicator is part of the monitoring for all measures.
Some aquatic organisms, such as crustaceans, insects, larvae, mussels, snails or worms (macrozoobenthos) have certain requirements for their habitat. They only colonise bodies of water with a certain oxygen content or a specific temperature range, for example.
Caddisfly larvae are the sister group of butterflies. They can use their silk to build so-called ‘caddies’, for example from plant parts or small stones of different sizes. Different species build different ‘houses’.
These animals occur in a breathtaking variety and each species has its own niche and tells us something about its habitat.
Macrozoobenthos in the IRIS project:
The composition of macrozoobenthos organisms reacts particularly sensitive to pressures on water quality (e.g. oxygen content), changes in the river bed or backwater. This is why macrozoobenthos, together with hydromorphology, was a ‘fixed starter’ and included in the monitoring for all IRIS measures.
Macrozoobenthos
Fish
Freshwater fish are among the most endangered animals on earth. In the course of their lifetime, they are dependent on a wide variety of aquatic habitats. For example, a gravel-spawning trout needs gravel banks to reproduce, the young fish then need shallow areas with not too much current, until the larger, older fish find themselves in deep pools (depressions in the river bed or bank areas with little current). In order to find these different habitats, fish have to migrate. The watercourse must therefore be well structured but above all it must be passable. Unfortunately, there are currently around 28,500 impassable barriers in our rivers, which often make this spawning migration impossible.
Fish are therefore the best indicator of hydromorphological changes such as a lack of connectivity.
Fish in the IRIS project:
A 5-metre-high ground sill is to be dismantled on the Pielach in order to make the section passable for fish again. The area is particularly important because the highly endangered Huchen, the so-called ‘Danube salmon’, has one of its last occurrences here. Huchen can grow up to 140 cm and weigh 50kg!
© DWS
Dragonflies sometimes develop as larvae in the water for several years before they venture into the air. Some species, for example, need a sandy substrate in the river for their development, which mainly occurs in well-structured rivers of a medium size – i.e. with a certain width, depth and flow velocity. So, if a freshly hatched animal is sitting on the bank, you have already learnt a lot about the river.
Dragonflies in the IRIS project:
Dragonflies offer an additional benefit for biological monitoring: they react particularly quickly to changing conditions thanks to their ability to fly and high mobility! Because dragonfly fauna can be used to document changes and hopefully successes very quickly, they are perfect for evaluating the effectiveness of measures, even within a limited time frame.
For more information on these colourful aerial artists, we have collected some curious dragonfly facts here.
Dragonflies
Flood protection
Flood protection is of course always a key issue in river management. Most of us think of dams and walls for flood protection. However, with such hard constructions, the water is only channelled further downstream and in the process gains speed. So while the situation may be improved locally, regionally the flood risk sometimes even increases.
If, on the other hand, the river is given enough space, then river channel extensions and dedicated floodplains can also be beneficial for flood protection. In these areas, the water can be held back deliberately. This relieves problem areas. Furthermore, dams and walls can always break. This so-called probability of failure is much lower with targeted water retention in the area.
© Bernhard Schubert
Flood protection in the IRIS project:
Flood protection is also evaluated as an indicator as part of LIFE IRIS monitoring. The relevant analyses require data on flood risk on the one hand and data on potentially affected assets on the other.
The following scenarios are calculated and compared for the status quo and for the implemented measure: (1) floods with a high probability (HQ30), (2) floods with a medium probability (HQ100) and floods with a low probability/extreme scenario (HQ300). The positive effects of the measures can be visualised through this comparison.
The figure shows, for example, the current flooding pattern of the Lafnitz in Rudersdorf. Analysing the affected protected assets before and after the implementation of measures provides a good overview of the effect of the measures on flood protection.
Natural river and floodplain landscapes are very dynamic ecosystems in space and time. Floods, seasonal changes in discharge and dry periods result in the constant restructuring and formation of new habitats in the river landscape.
Pioneer plants live up to their name and are the first plants to cover new sand and gravel banks. Willows, for example, have a very soft wood that allows them to bend rather than break during floods.
Many habitats and the animal and plant species they harbour are endangered (Red Lists), as the regulation of our rivers has left little room for these natural dynamics.
The result is the degradation or even loss of these important floodplain systems. Floodplain landscapes are important for biodiversity, as they provide a habitat for so many species, as well as for the local climate. Their cooling function is becoming increasingly important, especially in times of climate crisis.
Terrestrial ecology
Ecosystem services
Nature provides us with many services that we often take for granted – the so-called ecosystem services. The availability of drinking water, protection against natural hazards and attractive recreational areas are just a few examples and show the enormous importance that ecosystem services have on our lives and our quality of life.
An evaluation of ecosystem services helps to assess what additional benefits ecological improvements can bring.
Ecosystem services in the IRIS project:
In the IRIS project, we selected ecosystem services as indicators that are particularly meaningful for smaller restoration projects and for which sufficient data is available.
Within the scope of the monitoring, it is assessed, for example, whether the measures in the IRIS project have a positive effect on flood protection, protection against low water or sediment regulation. In the case of the reconnection of peatlands, the effect of the measures on the retention of greenhouse gases is also analysed.
