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REFRESH Catchment case studies - responding to future change: Louros catchment, Greece
The Louros catchment is situated in the central-southern part of the Epirus Water District in Greece. The river flows for 72 km before it forms a delta where it empties into the Amvrakikos Gulf. The Amvrakikos Gulf and its wetlands are highly biodiverse and a unique biogeographical refuge in the bird migratory route between Europe and Africa. It is classified as a European Union Special Protected Area (EU-SPA) under the Wild Birds Directive, a Site of Community Interest under the Habitats Directive, a Natura 2000 site and since 2008, a Wetlands National Park. The quantity and quality of Louros water and its capacity to carry sediments is critical for the ecology of the gulf and its unique landscape. Thus, the case study of the Louros river provides an example of the interconnected nature of the Water Framework and the Habitats Directives and disentangles the potential for synergies developed on the basis of sustainable management.
The Louros has been used as a major source of drinking water for more than 2000 years and now provides drinking and industrial water to the three largest urban areas of the catchment and many smaller towns. Farming, tourism, stock raising, aquaculture in the uplands and fish farming at the estuaries are the most important economic activities, directly or indirectly dependent on the quality and quantity of the water. At the same time, some of these activities together with illegal disposal of municipal wastes or individual disposal installations not connected to waste water treatment plants, present major threats to the water quality of the Louros. Additionally, the extensive reclamation works, both irrigation channels and drainage ditches, have reduced the flow velocity thus the capacity of the river to carry sediments to the estuaries.
Farming and stock raising activities, especially pig and poultry farming, are considered the most polluting in terms of nutrient enrichment and add further pollution loads from pesticide addition. Farming with high abstraction rates due to intense irrigation is also considered responsible for the low discharge rates. Although there is a lack of systematic environmental monitoring of the quality and quantity of the surface and sub-surface water, fragmented scientific work shows that the Louros has been affected in both qualitative and quantitative terms. Maize, medic (clove) and cotton are the most widespread irrigated arable cultivations requiring considerable fertilization, while wheat is mostly rain-fed with minimum fertilization. Citrus fruits are the most important irrigated perennial cultivation.
Planned Agri-environmental Mitigation Measures
High concentrations of nutrients (nitrates, ammonium and total phosphorous) have been observed close to the river estuaries. Planned agri-environmental measures allow compensation for farmers if they comply with measures or combinations of measures including the set aside of land, maximum allowable fertilization and irrigation per cultivation. Scientists and stakeholders in the area discussed measures for each of the major polluting cultivations. In the case of maize, cotton and clover, four alternative agri-environmental schemes were considered, mainly combinations of set-aside of irrigated land, reduced fertilization and crop rotation with N fixing legumes.
The costs of the proposed measures were calculated from information provided by local stakeholders and the average farm financial accounts per cultivation in the Louros catchment. The effectiveness of each measure was assessed in terms of reduced fertiliser applied in the catchment, as well as reduced concentration of nutrients in the river water. At baseline, without any mitigation measure in place, the models showed average annual concentrations of nutrients at critical points close to the estuarine zone were low enough to attain good status.
The baseline assessment raises two issues. First, the river is at a relatively good status in terms of nutrient concentrations despite the fact that it has been declared as a Nitrate Vulnerable Zone. This is surprising considering the catchment receives 1,780 tons of nitrogen and 1,160 tons of phosphorous of fertilizer every year. It may be that excess nitrate is efficiently removed by soil and in-stream processes in the lowlands and that the carrying capacity of the river is within the limits set by current farming practices. The second issue concerns the application of mitigation measures should it be desirable to lower, even further, the observed nutrient concentrations. This is related to the future of the catchment under climate change and is an important point because agri-environmental programmes are multiannual and frequently extended from one programming period to the other. Under the worst scenario for climate change projections and economic growth, the concentration of nitrates increases slightly, ammonium decreases slightly and TP and SRP remain stable. This is due to the fact that, despite land use changes, the amount of nutrients leaching from the soil decreases due to low precipitation and runoff, and the amount of nutrients transported to the estuarine zone is reduced due to lower mean flows. Thus, in the case of Louros, climate change is not forecasted to have significant impacts on nutrient concentrations. Under the worst climate change scenario, mitigation measures involving a combination of crop rotation with N-fixing legumes, 5% set-aside and reductions of N and P fertilizers, remains the most cost effective option, with no obvious gains in terms of reductions in nitrogen concentrations and significant gains for TP and SRP concentrations.
In the Louros, public awareness of the excess application of fertilizers shapes opinion and farmers become an easy target for public dissatisfaction about the state of the environment. Public opinion then pushes policy makers to take action and adopt programmes against nitrification. Farmers readily accept these subsidized programmes which have a quantifiable target, i.e., specific tons of nutrients abated. This may not be the most appropriate response as the adoption of agri-environmental policies is at risk of from two fallacies or ‘errors’. First, adopting a policy which is not really needed (Type 1) and second, not adopting a policy when it is needed Type 2). For the Louros, there is a risk of a Type 1 fallacy associated with very high levels of fertilization application that, due to physical and climatic factors, fail to produce excessive nutrient concentrations in the water. A Type 2 fallacy could arise with moderate or low fertilization application under a low absorbing capacity soil - hydrosphere system resulting in elevated nutrient concentrations in the water. Both cases can be negatively or positively affected by future climate change. When the fertilizer application period coincides with reduced precipitation and runoff due to climate change, even a highly impacted system may show less nutrient concentration while a moderately impacted system may, under extreme climate events, present unprecedented nutrient concentrations
For further information see REFRESH reports
Report from workshop in Greece to explore discrepancies between different groups of stakeholders regarding their perceptions of the policy implementation issues the underlying factors that explain these differences, REFRESH deliverable 1.15, University of Patras, Greece