The application of the Shorezone Functionality index on Italian, Austrian and Slovenian lakes within the SILMAS project
International working group Maurizio Siligardi, Barbara Zennaro (Agenzia provinciale per la protezione dell’ambiente) Rossano Bolpagni (università di Parma, Regione Lombardia) Roswitha Fresner, Michael Schönhuber (Carinthian Institute for Lake Research) Liselotte Schulz (Government of Carinthia, Dep. 8 – Environment) Tina Leskosek (National Institute of Biology, Slovenia)
Coordination Maurizio Siligardi, Barbara Zennaro (Agenzia provinciale per la protezione dell’ambiente).
Authors Maurizio Siligardi, Barbara Zennaro (Agenzia provinciale per la protezione dell’ambiente). Rossano Bolpagni (Università di Parma, Regione Lombardia) Michael Schönhuber (Carinthian Institute for Lake Research) Tina Leskosek, Irena Bertoncelj, Uros Zibrat, (National Institute of Biology, Slovenia)
Acknowledgement Special thanks from APPA to all those that hosted and participated to the SFI trainings during summer 2012 and all those that supported the working group to carry on the work. APPA non è responsabile per l’uso che può essere fatto delle informazioni contenute in questo documento. La riproduzione è autorizzata citando la fonte.
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Summary 1. The SILMAS project.................................................................................................................... 4 2. The importance of the lake shorezone................................................................................ 6 3. The Shorezone Functionality Index...................................................................................... 8 4. The Shorezone Functionality Index as a management tool. ....................................... 12 5. The application within the SILMAS European Project. .................................................. 14 6. SILMAS Lake Reports. ............................................................................................................. 16
Levico Lake........................................................................................................................... 17
Caldonazzo Lake.................................................................................................................. 21
Idro Lake............................................................................................................................... 26
Wörthersee............................................................................................................................ 28
Millstätter See....................................................................................................................... 31
Lake Bohinj........................................................................................................................... 34
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1. T he SILMAS project
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The Alpine lakes share a common identity, rooted in their geographical location and the cultural and economic benefits they generate. Given how difficult it is to reconcile environmental protection and human activity, lake managers (elected representatives, government bodies and local associations) decided to pool their experience to solve the problems they all faced. To this end, five countries - France, Italy, Slovenia, Germany and Austria (figure 1) - formed a network of Alpine lakes. Launched for a three-year period (2009/2012) as part of European territorial cooperation, SILMAS (Sustainable Instruments for Lake Management in the Alpine Space) is a major project aimed at pooling experience and know-how in sustainable Alpine lake management. SILMAS follows on from Alplakes, an earlier network of Alpine lakes.
SILMAS objectives are • Share ideas and experience across a European network • Produce concrete tools (technical guides, training programmes, educational games) to help Alpine lake managers protect their resources • Raise public awareness of the need to protect and sustainably manage this fragile environment
SILMAS work priorities are • The probable effects of climate change on the Alpine lakes, and how to tackle them • Managing water usage conflicts •Educating the public in sustainable development as it relates to the Alpine lakes
Figure 1> Countries participating to the SILMAS project.
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2. The importance of the lake shorezone
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While most of earlier indices were characterized by a particular analysis, for example to the water itself (chemical analyses) or to the biotic environment (biological extended index), the lake Shorezone Functionality Index (SFI) looks at the overall status of the lacustral environment and assists in the identification of the causes of deterioration, zooming out from the waterbody itself to also include all the surrounding territory and watershed topography. The area around the shores is a transition zone (ecotone) between the surrounding territory and the lake and guarantees the execution of the ecological processes needed to protect the lake from the wateshed’s no-point sources of pollution. Its structure and the extension are influenced by the topography, the climate and the soil’s geological composition, while its water fluxes, the nutrients and sediment inputs, and the diffusion of animal and plant species are influenced by the lake riparian vegetation.
By “shorezone”, it is meant that area that includes the littoral (maximum depth of 1 meter) and the riparian zones, and it extends inland up to 50 meters from the shoreline (with the exception of interruptions or particular lake morphology which may limit its width) (figure 2).
Figure 2> Structure of the lake shorezone.
The riparian zone, the area immediately adjacent to a body of water functioning as a transition between the lake and the surrounding territory, is important as it regulates inputs (nutrients and sediments), improving the lake water quality by filtering the runoff from the catchment area and removing pollutants (the vegetation in the riparian zone can remove up to 90% of the nutrients passing through) and by aiding sedimentation (the vegetation slows the water flowing into the lake); it also provides habitat to aquatic and terrestrial animals, including food, shade (temperature control), shelters, areas for hunting and breeding; moreover it protects the shoreline from erosion, favoring the bank stabilization.
An healthy littoral zone (the first meters from the shoreline into the water) also provides habitat, food and nesting materials for aquatic and terrestrial animals, it is important for nutrient cycling and also protects the shoreline from erosion, favoring a good water clarity (through reduced wave action). By “Lake Shorezone Functionality” it is meant the capacity to accomplish those determinate functions.
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3. The Shorezone Functionality Index
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The importance of understanding and evaluating the lake shorezone functionality lead to the creation of a new system of indicators that could evaluate the shorezone functionality. The Shorezone Functionality Index was developed in Italy in 2004 by the National Environmental Protection Agency (APAT, now ISPRA)’s working group, coordinated by the Provincial Environmental Protection Agency (APPA) of Trento. It was created as the twin brother of the already existing Fluvial Functionality Index (2000) and tailored to the reality of the Alpine lakes. It was later integrated within the AlpLakes European Project for the lakes in region Lombardy (Italy), within the Silmas European project for the lakes along the alpine arch (Italy, Austria and Slovenia), within the Eulakes European Project modified for the big lakes of central Europe (Italy, Austria, Poland and Hungary) and finally ran in the lakes of by Aracaunia (Chile), by the University of Villarica, for the Chilean Environmental Agency. Both biotic and abiotic factors are used to evaluate the buffering capacity of riparian vegetation, the complexity and artificiality of the shoreline, the anthropogenic use of the surrounding territory, and the way the inputs enter the water body from the watershed. The SFI application consists in filling out two forms: the first form collects general information about the lake and its watershed (topography, morphology, climate…); the second form is filled out for each homogeneous shorezone stretch identified in the field. The “homogeneous shorezone stretch” is a stretch of
shore that has similar ecological, morphological and functional characteristics and can be therefore described in a single form. Every time there is a change in one or more parameters (for example artificialization, shore zone width or composition), a new form is used to describe the next homogeneous shorezone stretch. Different parameters are surveyed and evaluated in the field with an ecological point of view. They include ecological parameters (typology, width, continuity or interruption of the riparian vegetation), socio-economic parameters (land use, presence of infrastructure…) and other general parameters (steepness, concaveness, shore artificiality…). Each surveyed parameter has its own numeric weight, and a dedicated software (SFINX02) runs the parameter collected for each homogeneous stretch through a classification tree (figure 3) that will lead to different functionality levels.
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visuel italien
Figure 3> The classification tree in the SFI software.
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During the phase of the index development, nine parameters were identified, through a neural network analysis, as the ones influencing the most the shore functionality (figure 4). There parameters are: • Shore artificiality • Presence of grass • Interruption of the lake-shore-zone • The presence of road Infrastructure • The concavity of the shore profile • The presence of reeds • The presence of arboreal species • The heterogeneity of arboreal vegetation • The presence of non-hygrophilous species Each node of the classification tree shows the probability of each homogeneous stretch to fall into one of the five categories (as suggested from the WFD 2000/60/CE), ranging from I - Excellent to V - Bad). The higher percentage will determine the level of functionality (table 1). The results and parameters are then transferred into a GIS platform in order to create thematic maps of the parameters surveyed and to be able to carry out spatial analysis. The SFI maps are very important as they provide a first direct sight of the general status of the lake shorezone (figure 5), for example indicating the location of remaining areas of high functionality (blue colour). The length of each homogeneous stretch, and therefore the total lake perimeter length for each category, can also be calculated in a GIS. It is also possible to create different thematic map showing the different parameters (figure 6), for example the shorezone artificiality or the presence of exotic species. Different layers, such as the surveyed parameters, the soil use, the presence of houses, presence of waste water collectors etc., can be overlaid to carry out spatial analysis and identify the weaker or stronger locations, areas more in need or more prone to restoration actions. It is important to keep in mind that shore “naturality” and “functionality” are two different concepts. In fact, even if totally natural, a shore may have low levels of functionality in specific cases: for example, steep cliff falling directly into the lake with no or little riparian vegetation are in fact not able to carry out any good ecological function.
Figure 4> Example of results from an homogeneous stretch in SFINX02.
LEVEL
JUDGMENT
COLOR
I
Excellent
BLUE
II
Good
GREEN
III
Moderate
YELLOW
IV
Poor
ORANGE
V
Bad
RED
Tab. 1> Functionality levels, relative judgments and reference colors.
Figure 5> S horezone Functionality Index for Caldonazzo lake. The map provides a first direct insight on the status of the lake.
Figure 6> T hematic maps for Caldonazzo lake showing the with (“ampiezza”) of the shorezine (red = 0 meters, green = more then 40 m), and the artificiality (“artificialità”) of the shorezone (red = 100% artificial, blue = natural shore).
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4. T he Shorezone Functionality Index as a management tool
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The potential of the SFI method lies in the ability of obtaining a synthetic value of lake shorezone functionality. The SFI approach permits to complete the study of the internal lake’s dynamics, often modified for production or recreational-tourism purposes. A lake’ shorezone management based on the concepts of its functionality allows to reconcile the environment protection with the human use of the lake, helping an eco-sustainable city planning and watershed management. Lake managers and stakeholders can use these results for a sustainable ecosystem-based watershed management. The results obtained provide, relatively economically and in short period of time, an immediate general picture of the state of the shores around the lakes, in opposition of earlier indices that were representative only of specific points along the shore. The results can also be used to easily identify the location and the actions needed in potential restoration sites (different scenarios can be modeled in a specific area with SFINX02 changing determinate parameters to foresee the impacts that public or private work may have on the waterbody), location of protected areas, location of areas of important economic value and so on.
understand the results. It highlights the shorezone weakness and strengths and include specific indications of actions needed to improve the lake functionality. The report includes the following chapters: • Introduction to the Shorezone Functionality index • Lake’s location, origin and history • Results, statistical analysis and management recommendations • Application of the Shorezone Functionality Index (description of each homogeneous stretch one by one, with photos, SFI result and specific recommendation when applicable)
SFI answers to the current needs, as requested by the 2000/60/ CE directive, to develop new indices able to assess the hydromorphologic elements of the lake’s ecosystems, including the riparian zone.
The SFI thematic maps can be created for each parameters collected in the field. A shapefile containing this information is created for each lake and for each SFI study. Importing the results into a GIS environment allows to carry out geospatial and geostatistical analysis. For example, SFI studies carried out in a specific lake in 2 different years can be overlapped to extract information on changes in the shore functionality throughout time.
Future SFI reports in the same lake can also be used to track changes along the shorezone throughout time. Different output formats within this project are created to reach the final users, may they be managers, locals stakeholders or tourists. The outputs include the SFI report, the SFI thematic maps and the SFI brochure. The SFI report describes the lake and all the homogeneous stretches identified, and is written so that the reader, not necessarily familiar with the index or the lake, will be able to
The SFI brochure was studied to share the results with a general public and it is usually available in both English and the local language. The brochure describes shortly the methodology, the lake main categories, a summary of the statistical results and management suggestions.
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5. The application within the SILMAS European Project
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Within the SILMAS European Project, Italy, Austria and Slovenia cooperated together in applying the Shorezone Functionality Index on their project lakes. The Shorezone Functionality Index (SFI) is an index that evaluates the capacity of the area located just adjacent the lake shore to accomplish determinate ecological functions, such as the purification of waters coming from the surrounding watershed and their capacity to host aquatic animals. The SFI reports give specific indications on what actions are needed to improve the functionality of the shorezone and can therefore be used to plan, monitor and evaluate restoration efforts. Similarly, different scenarios can be modeled in a specific area to foresee the impacts that public or private work may have on the waterbody. The data can be entered into a GIS system, in order to carry out further spatial analysis and easily display the results in maps. For these reasons, this index represents an important and powerful tool that can be used for sustainable planning and management. Between summer 2010 and 2011, APPA offered different seminars on SFI methodology and implementation to 3 Silmas’s project partners: Region Lombardy in collaboration with University of Parma for lake Idro (Italy), the National Institute of Biology - Department for freshwater and terrestrial ecosystem Country
Lake
Partner
IT
Caldonazzo
APPA
Barbara Zennaro
IT
Levico
APPA
Barbara Zennaro
research (Slovenia), and the Department of Environment of the Regional Government of Carinthia (Austria). These 3 entities subsequently and autonomously carried out the index on their own lakes, providing as well useful feedback to further improve the index. The first results and the comments collected by the partners lead in fact to the update of the SFI software SFINX into the newer version SFINX02, corrected for some bugs and graphically improved. As a project output, 6 lakes have been surveys the SFI index (table 2), their location shown in figure 7. The following chapter shows an extraction of the SFI report (chapter 2 and chapter 3) including indication on where to find the full report and more information about the index.
Contact Person
IT
Idro
Reg. Lombardia
Rossano Bolpagni
AT
Millstätter See
ABT 8
Michael Schönhuber
AT
Wörthersee
ABT 8
Michael Schönhuber
SL
Bohinj
NIB
Tina Leskosek
Table 2: Lakes participating to the SFI surveys.
Figure 7> Location of the SFI/SILMAS lakes.
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6. S ILMAS Lake Reports
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Levico Lake Location and Origin Levico lake is located in the Province of Trentino, Italy (figure 8), close to the homonymous touristy town of Levico (population = 7.300) which is located on the southern-eastern section of the lake (figure 9 and 10).
Figures 8, 9, 10> Location of Levico and Caldonazzo lakes, delineation of their watersheds and satellite images of Levico’s surrounding territory.
The lake is located 400 meters a.s.l, and its shape reminds of a Norwegian fjord. It was originated, similarly as the neighboring Caldonazzo lake located on the other side of Tenno’s hills, by an alluvional damming created by Rio Maggiore. The tributaries are the Visintainer and the Rio Maggiore streams. Its only emissary joins the waters coming from Caldonazzo lake few hundreds meter downhill, forming the springs of the Brenta river. The transparency (Secchi disk) is about 5 meters (7,6 m in winter) and the lake water have a deep blue color. Its extension is big enough to mitigate the surrounding climate, and its shores host two beaches with a park and a camping, all of them very frequented during the summer season.
The surrounding territory is mainly characterized by coniferous forest running all the way to the water, some agricultural fields and the developed area of the Levico town (figure 10). Field work in Levico lake was carried out by Maurizio Siligardi and Barbara Zennaro, from the Settore informazione e monitoraggi of the Environmental Protection Agency of the Province of Trento, on the 29th September 2010.
Results In Levico lake, most of the shorezone shows an excellent to good functionality (figure 11), with homogeneous stretches able to carry out different ecological functions, such as nutrient removal from surface water running into the lake, shore erosion protection, providing habitat for aquatic and terrestrial species.
Figure 11> SFI results for Levico Lake.
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Lower values are generally due to the presence of exotic species, lack of hygrophilous species and an increasing level on human pressure. On 6 individuated homogeneous stretches, more then ¾ felt under the excellent and good category (83%) and were characterized by a shorezone composed by green forests, partly penalized by the presence of exotic species and no-hygrophilous species (figure 12). The remaining two stretches felt under the categories moderate and poor (17%) and are represented by the camping (that obtained a better result compared to the public beach thanks to the presence of the reeds and different arboreal riparian species) and the public beach.
BASSE DEF Figure 12> Percentage distribution of the functionality level of Levico Lake.
SFI Value
Stretches identified
Total m
Percentages
Excellent
3
1368
21%
Good
1
3970
62%
Moderate
1
350
5%
Poor
0
0
0%
Bad
1
790
12%
TOTAL
6
6478
100%
Table 3> Results for Levico Lake: along Levico’s perimeter, 6 homogeneous stretches were identified, for a total of 6,5 km of lake perimeter.
SFI Category 1 and 2 These categories occupy most of the lake perimeter, and are characterized by steep hills covered predominantly with dense native vegetation mainly no-hygrpphylous that growth without interruption growing until the lake shore (figure 13). Paths or accesses to the shore are absent in the western part of the lake, while a small fisherman path reaches the emissary on the northern side of the lake (figure 14). The shorezone should be able to filter any cause of no-pointsource of pollution (and storm water run-off), despite of the steepness of the area and the surrounding environment (0-200 meters from the coast) and the penalization due to the presence of exotic species (such as robinia) and no-hygrophilous species.
Figures 13, 14> Examples of categories 1 and 2.
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The second identified pristine stretch is the protected biotope hosting reeds (instituted by the Province of Trento in 1988 and 1994) located on the southern end of the lake (figure 15). The territory surrounding this stretch is poor in vegetation, composed mainly by shrubs and small trees and it is partly urbanized. The third identified pristine stretch encloses the small area surrounding the Brenta emissary. This area is characterized by the presence of older trees on the left side of the emissary, and of a man-made area of the right side.
Figure 15> Examples of categories 1 and 2.
SFI Category 3 and 5 The low SFI result is mainly due to the high artificiality of the shore and the lack of riparian vegetation: superficial waters and possible no-point source pollutant can flow directly into the lake in this area without encountering any particular barrier. The two stretches falling into this category are the artificial public beach, composed by shingles and cobbles (figure 16), and a private camping site, composed by bare soil slightly covered by small trees planted probably for shading. There are small pools of wet reeds and few riparian trees, which are separated from the land by an impermeable sustaining wall.
The presence of bare soil and the high population density during the tourism season, make this stretch very sensitive to pollution issues.
Figure 16> Example of SFI category 5.
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Lake Levico Management Recommendatio Levico lake is generally an healthy lake suffering from a seasonal human impact during the summer months. Definitely the presence of woods around the lake protects it by possible source of pollution that may come from the cultivation in Tenna’s hill (on the western site). Levico Lake does not present any particular issue regarding water quality and no particular management actions are suggested for the management of this lake. The stretch with the artificial beach could be improved by replacing the broken impermeable wall with a permeable one, constructed with woods and rocks, allowing the growth of the reeds in certain spots, also to ensure an healthy habitat and a safe corridor for aquatic animals.
Authors Barbara Zennaro, Maurizio Siligardi Agenzia provinciale per la protezione dell’ambiente Settore informazione e monitoraggi Piazza Vittoria, 5 - 38122 Trento Tel. 0461 49 77 39 - Fax 0461 49 77 69
[email protected] [email protected]
For more information Agenzia provinciale per la protezione dell’ambiente Settore informazione e monitoraggi Piazza Vittoria, 5 - 38122 Trento Tel. 0461 49 77 39 - Fax 0461 49 77 69
[email protected] [email protected] www.appa.provincia.tn.it
Full report available at http://www.appa.provincia.tn.it/appa/pubblicazioni/-Acqua/
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Other recommendation is the frequent control of the quality of main tributaries to avoid discharge of nutrient from the surrounding environment. It is also recommended to promote lake environmental education, such as sensitization campaigns for local stakeholders and managers on the role of the lake and classes on lake ecology for schools, maybe using the concept of the “house on the lake”, as proposed in the SILMAS project.
Caldonazzo Lake Location and Origin Caldonazzo lake is located in the Province of Trentino (Italy), close to the town of Pergine (population =20.580) which is located on north section of the lake (figure 17, 18, 19).
BASSE DEF Figures 17, 18, 19> Location of Levico and Caldonazzo lakes, delineation of their watersheds and satellite images of Caldonazzo lake’s the surrounding territory.
Caldonazzo lake is the first natural lake for extension entirely located in Trentino. Its extension is big enough to mitigate the surrounding climate: Caldonazzo means “warm”: even if it is an alpine lake, it is very popular for bathing, as its average temperature in summer months - June 20°C, July 23°C, August 24°C - is perfect for a refreshing bath and to practise water sports. The lake is located in the district C4, High Valsugana, and is divided into 5 municipalities: Pergine, which occupies the larger area, Calceranica, Caldonazzo, Bosentino and Tenna. The State Road 47 Valsugana runs along the eastern embankment of the lake, but its impact is often mitigated by the presence of various tunnels. This road connects the capital city of Trento with the Veneto Flat and then Padova and Venice, crossing all Valsugana Valley. Along the western embankment of the lake instead, often limiting the width of the shorezone, there are the main road connecting Pergine with Calceranica, the Valsugana Railway and the pedestrian/bicycle track, all running parallel to each other. Date
Surveyors
16 June 2010, by feet
Maurizio Siligardi, Barbara Zennaro, Catia Monauni, Renato Grazzi
12 October 2010, by boat
Maurizio Siligardi, Barbara Zennaro, Renato Grazzi
12 April 2012, by boat
Barbara Zennaro, Gaetano Patti, Renato Grazzi
The lake was originated, similarly as the neighboring Levico lake located on the other side of Tenno’s hills, by an alluvional dam created by the old course of Fersina river and by the Rio Mandola. The main tributary is the Rio Mandola stream, complemented by other little streams around the lake (Fos dei Gamberi, Fos dei Lavatoi, Rio da Ischia). Its only emissary, on the eastern side of the lake, joins the waters coming from Levico lake few hundreds meter downhill, representing the springs of the Brenta river. Field work in Caldonazzo lake was carried out in different dates by foot and by boat. The following table summarizes the field work date and surveyors, from the Settore informazione e monitoraggi of the Environmental Protection Agency of the Province of Trento.
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Results The lake was strongly eutrophic during the 70’s and its environmental conditions were low: the water had a low transparency value (Secchi Disk’s value of 80 cm), high chlorophyll and nutrient content. Given the tourist value of the lake, the provincial authorities decided to act on different restoration actions, consisting of: 1. A collection system was built to collect all urban wastewater existing along the lake 2. The deep water was oxygenated with a Swedish method, consisting of big bells located at a depth of 12 meters blowing compressed water. The air mixed with the water and was distributed in a radial way in the lake. To date, the bells are still in part functioning 3. The deep water was also removed with a siphon located close to the Brenta emissary 4. The remaining pristine shorezones were protected.
The positive effects of these actions were already visible after only 3 years, but it took the lake 35 years to restored the trophic condition needed for the tourist industry. The shore generally shows an high level of artificiality, with only few places left pristine (figure 20). Extended reeds belts are present only in the northern side of the lake, where they constitute the protected biotope (instituted by the Province since 1988 and 1994) and in the southern end, where the lake waters exit to form the Brenta river. The two main roads running north to south along the eastern and western shores of the lake often represent a limitation of the shore width, with the exception of those areas (in the eastern side), where the tunnels allow a continuity of vegetation from the shore to the surrounding environment.
Figure 20> SFI results for Caldonazzo Lake.
SFI Value
Stretches identified
Total m
Percentages
Excellent
6
2346
19%
Good
4
1198
10%
Moderate
4
3041
25%
Poor
1
238
2%
Bad
14
5494
44%
TOTAL
29
12317
100%
Table 4: Results for Caldonazzo Lake: 29 homogeneous stretches were identified, for a total of 12.3 km of lake perimeter
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On 29 individuated homogeneous stretches, nearly half (44%) shows a Bad value. These are the stretches with beaches and cemented sustaining walls built right on the water-land interface. The second bigger class is Moderate (25%), and represents stretches with a restricted shorezone width which although still hosts vegetation. The remaining classes, Good (10%) and Excellent (19%) are represented by those areas where the reeds is present and where the road tunnels allow a continuum between the shore and the surrounding environment, increasing the functional shorezone width (figure 22).
BASSE DEF Figure 22> Percentage distribution of the functionality level of Caldonazzo Lake.
SFI Category 1 and 2 These categories are located in coincidence with areas where the shorezone width is wider thanks to the presence of reed belts or thanks to the continuity with the surrounding environment given by the road tunnels. The vegetation is here mainly hygrophilous and a good shore functionality is assured (figures 22 and 23).
Because their extension occupied only the 29% of the whole lake perimeter, it is advisable to safeguard these areas (most are in fact already protected thanks to the special instituted biotopes). An improvement could be given with the growth of a reed belt, but further study are necessary to verify this possibility.
Figures 23, 24> examples of SFI categories 1 and 2.
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SFI Category 3 The stretch occupies most of the western side of the lake, running along the pedestrian-bike path (figure 24). Even though the riparian vegetation is almost continuous and there is a good diversity, the width of the lake shorezone is penalized by the presence of the path running along it. The provincial road running parallel to it could also represent a source of pollution for the lake, and it is therefore important not to worsen the condition of this stretch.
Figure 24> Example of SFI category 3.
SFI Category 4 and 5 The low SFI values are given by the high artificiality of the shore and the lack of riparian vegetation: superficial waters and possible no-point source pollutant can flow directly into the lake in this area without encountering any particular barrier. The stretches in this category fall into two main typologies: the first is constituted by artificial beaches made of small pebbles
Figures 25, 26> Examples of SFI categories 4 and 5.
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or English gardens, covered by few trees probably planted for shading (figure 25); the second typology, located in the southern-eastern side of the lake, is characterized the presence of impermeable sustaining walls that support garden for private summer houses, and that causes an interruption between the lacustrine and terrestrial environment (figure 26).
Caldonazzo Management Recommendations Caldonazzo Lake improved its quality thanks to the restoration works accomplished in the past years, such as the waste water collector. Although, the absence of a vegetation buffer zone, especially along the southern shores where the pressure from agriculture is higher, represents a weakness. Another threat for the shorezone functionality is represented by the requests to continuously expand the beaches, parking and tourist structures, all actions that will increase the artificiality of the shorezone, therefore loosing existing areas with good functionality. In the past fifthy years, the use of Caldonazzo lake leaned more and more toward a tourism related use. This resulted in a gradual decrease of natural areas to create new beaches, tourist infrastructures, summer houses, roads and parking. The SFI index showed how these human actions affected the lake shorezone functionality. Nowadays, the lake offers many tourist attractions and it would be recommended to improve the quality of the tourist offer, rather than the quantity, assuring an ecological vision with protection of the already existing natural sites.
It is therefore recommended to: • Preserve the already existing natural areas, including the protected biotopes • Consider an environmental friendly development, limiting the use of cement • Keep the current limitation on the use of boat engines • Supervise the tourist offer growth/development • Publicize the tourist offer considering the natural aspects of the lake • Organize a sensitization campaigns for local stakeholders and managers on the role of the lake and its need to be healthy • Promote lake environmental education in schools, maybe using the concept of the “house on the lake”, as proposed in the SILMAS project
Authors Barbara Zennaro, Maurizio Siligardi Agenzia provinciale per la protezione dell’ambiente Settore informazione e monitoraggi Piazza Vittoria, 5 - 38122 Trento Tel. 0461 49 77 39 - Fax 0461 49 77 69
[email protected] [email protected]
For more information Agenzia provinciale per la protezione dell’ambiente Settore informazione e monitoraggi Piazza Vittoria, 5 - 38122 Trento Tel. 0461 49 77 39 - Fax 0461 49 77 69
[email protected] [email protected] www.appa.provincia.tn.it
Full report available at http://www.appa.provincia.tn.it/appa/pubblicazioni/-Acqua/
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Idro Lake Location and Origin Lake Idro is a south alpine deep lake located in the Northern part of Italy at an altitude of 368 m a.s.l. across the provinces of Brescia and Trento (between Lombardy and Trentino-Alto Adige Regions). The lake surface is equal to 11.03 km2, with a maximum length of 9.4 km, a maximum depth of about 124 m and a volume of about 8.5* 108 m3. According to its trophic status the lake has been considered to be meso-eutrophic; limnologically, the lake belongs to the meromictic type of circulation. Currently, the upper mixed water zone (the oxic layer) varies between 40 m and 50 m of depth and approximately more than 50-60% of the entire lake volume is permanently stratified and oxygen-free. The basin plays an important part in the economy of the local population essentially in terms of tourism and recreation; however, it is also the first Italian natural lake completely converted into a hydroelectric reservoir in the mid-1930s. As a
consequence of the huge drawdown and water level fluctuations imposed by hydropower exploitation, and the increase in pollutants delivery from the its catchment, since early 1970s, the basin has been shown a progressive worsening of water quality and biotic component. A major ecological effect of these external perturbations is the increase of the bottom layer of water (usually free of oxygen) moved from about a depth of 7080 m (late 1960s) up to currently 40-50 m. In the last ten years, a progressive steep reduction in the amplitude of artificial water level fluctuations, coupled with the accumulation of organic matter and nutrients in waters and surface sediments, have enhanced a rapid and intense proliferation of littoral vegetation and recurrent cyanobacterial blooms. The present investigation has been carried out from a boat (performing a complete circumnavigation of the lake during the surveys) and integrating them with aerial photographs.
Results On the whole, Lake Idro has 26.670 m of shoreline divided into 44 distinct stretches, few of which are submitted to intense anthropogenic perturbations that resulted in a localized alteration of the lake shores and/or beaches (figure 27). Consequently, a poor SFI value is exclusively associated to the 16% of the total length of the shoreline (about 4.340 m) that comprised the littoral sector of the lakeside towns and built-up areas, splitting into 8 distinct stretches with very low values of functionality. No shoreline sectors with a fair evaluation (4, SFI value) have been
BASSE DEF Figure 27> Results for Lake Idro.
SFI Value
Stretches identified
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BASSE DEF Figure 28> Percentage distribution of the functionality level of Idro Lake.
Total m
Percentages
Excellent
4
2400
9%
Good
17
10780
40%
Moderate
15
9150
34%
Poor
0
0
0%
Bad
8
4340
16%
TOTAL
44
26670
100%
Table 5> Summery of the SFI results.
pointed out; on the other hand, 15 stretches show a moderate level of shorezone functionality with a total length of about 9.150 m, in presence of slight levels of human pressure that resulted into a moderate alteration of littoral and hydro-hygrophilous vegetations (e.g., periodical cutting of riparian belts, installation of quays or boas). The remnant stretches (21 lake sectors with a length of 13.180 m equal to the 50% of total shoreline extension) display a good or excellent conservation stages in presence of natural and near-natural conditions (figure 28).
SFI Category 1 and 2 These categories represent in total the half of the lake perimeter with a clear predominance of the “good” conditions (equal to the 41%). To the excellent class are related 4 lake sectors that included stretches in natural conditions, not easily reachable by humans if not by boats (figure 29). These sectors are characterized by well-developed fringes of hydro-hygrophilous vegetation, although in general the water-terrestrial ecotones are mostly reduced to a thin belt of about 5-10 m. The second category is differentiated by the irregular presence of paths and not-paved sidewalks used as approaches to the lake shore, sparse residential settlements or not-intensive agricultural areas. Generally, these stretches display a near-natural condition with good conservation status characterized by, in the main, continuous riparian and littoral vegetation stands and only sporadic presence of artificial substrates.
BASSE DEF Figure 29> SFI Category 1 and 2.
SFI Category 3 The third category includes the stretches that are characterized by non-negligible levels of anthropogenic pressures; however in presence of several natural attributes as well as wet fringe vegetations or littoral ecotones, although, the expected helophytic communities are frequently replaced by invasive or less exigent species. Nevertheless, these sectors are included into not-intensive agricultural lands and neighbourhoods (figure 30).
BASSE DEF Figure 30> SFI Category 3.
SFI Category 5 Category 5 includes the artificial shorelines (in presence of retaining walls, piers, docks, etc.) that are classified in the worst functional status. This typology is prevalently found in the urban contexts, especially in the southern and northern sectors of the basin. Natural vegetation is scarcely represented and frequently these sectors are characterized by beaches that are periodically repaired using allochthonous materials (figura 31).
BASSE DEF Figure 31> SFI Category 5.
Management Recommendations Lake Idro shows rather high Shorezone Functionality Index (SFI) values; at least 84% of its shoreline is in a good status of conservation. Our results suggest that high levels of anthropogenic alteration are only detected in correspondence with urban residential and settlements areas. Generally, the good status of littoral and riparian contexts is in contrast to the current worst status of water quality. Among the human pressures, in
fact, agricultural activities in the watershed and wastewater from resident population and from trout farms are probably the most relevant. Nevertheless, the presence of well preserved fringe vegetations (e.g., hydro-hygrophilous plant belts) guarantees an efficient filtering functionality and stimulates a rather slow but constant control of the exogenous input and the internal nutrient load.
Authors
For more information
Dr. Rossano Bolpagni
Dr. Rossano Bolpagni
Dipartimento di Scienze Ambientali, Università degli Studi di Parma - Department of Environmental Sciences, University of Parma V.le G.P. Usberti 11 / A - 43125 Parma
Dipartimento di Scienze Ambientali, Università degli Studi di Parma - Department of Environmental Sciences, University of Parma V.le G.P. Usberti 11 / A - 43125 Parma
Tel: (+39) 0521 905696
Tel: (+39) 0521 905696
[email protected]
[email protected]
27
Wörthersee Location and Origin As one of the most popular bathing lakes the Lake Wörthersee is situated in Carinthia, close to its capital, Klagenfurt, located near the eastern shores of the lake. With an area of 19,39 km² and a length of 16,5 km Lake Wörthersee is even the largest lake of Carinthia. It is situated in a valley aside off the main draining line of the river Drau and embedded in the hilly Mittelkärntner Hügelland. The valley ridge is a tectonic disorder, which was covered by an ice age glacier. The lake basin stretches from the east to the west, is structured by islands, peninsulas and underwater rises and parted into three. The maximal depth amounts to 85,2 m, while there is a average inflow of 2.460 l/s. A great number of smaller brooks flow in from all sides of the lake. The biggest is the Reifnitzbach with an average substance of 630 l/s. The water residence time of 10,5 years has been calculated. As a consequence of the strong burdens with nutrients (eutrophication), which were caused by the quick development of tourism during the 1960s, the oxygen-free zone of this
meromictic lake moved from about a depth of 70 m up to 45 m. The pollution with phosphor-polluted waste water grew up rapidly and algae blooms appeared, severely handicapping the bathing activities and tourism. In 1963 the responsible authorities reacted, setting measures and implementing a law for keeping clean the lakes. As the first guiding project the purification plant Klagenfurt (1967) was built. These measurements of stabilization in the catchment area (like the built of the drainage system around the lake) made the lake again a major attraction magnet for summer tourism. The lake`s name has its origin in the Old High German “Werdersee”, meaning lake with 4 islands. One of them, Maria Wörth, was connected to the mainland by decreasing the water level in 1770. The investigation for the SFI has been carried out by using videos, taken from boat and helicopter, and integrating them with aerial photographs and on-site surveys.
Results The overall shoreline of Lake Wörthersee amounts to 46.300 m. Most of it is interested by a huge anthropogenic pressure, resulting in diffused settlements along the lake waters (figure 32). Popular bathing localities like Velden, Pörtschach and Maria Wörth attract many tourists during the summer months. As a result, nearly 50 % of the shoreline shows a poor SFI value. Human disturbance results in artificial shores and impermeable sustaining walls. 15 stretches without functionality has been
BASSE DEF Figure 32> SFI results for Lake Wörthersee.
SFI Value
Stretches identified
28
BASSE DEF Figure 33> Percentage distribution of the functionality level of WörtherseeLake.
Total m
Percentages 11%
Excellent
8
5269
Good
6
2294
5%
Moderate
13
17136
37%
Poor
0
0
0%
Bad
15
21601
47%
TOTAL
42
46300
100%
Table 6> Summery of the SFI results.
encountered during the survey. 10 from the remaining 16 stretches resulted to have a moderate shorezone functionality. Its length amounts to 6.755 m, where human interventions, especially in front of private properties, result in decreased hygrophilus vegetation and the installations of piers for bathing purposes. The remaining sections stand in the range of excellent/good values, natural and near-natural conditions could be achieved (figure 33).
SFI Category 1 and 2 These categories occupy together just 17 % of the lake perimeter. The excellent condition is characterized by areas under nature protection (protection area “Walterskirchen” and area around the lake outlet, the Glanfurt) or by stretches in nearnatural conditions. The first are distinguished by the presence of hygrophilous species and extensive weed-patches. Stretches in near-natural conditions sometimes also resulted to be in a
good state, as some of those stretches are rather narrow and characterized by the close presence of paved streets. Such streets run all around the lake and often approach the lake shore. The surrounding territory of these stretches in excellent/ good conditions is distinguished by hilly, mostly woody territory. Sometimes there are sparse residential settlements, while intensive agricultural areas are lacking (figure 34 and 35).
BASSE DEF Figures 34, 35> SFI Category 1 and 2.
SFI Category 3 This category is distinguished by stretches that result under clear anthropogenic pressure, but still presenting some natural attributes: permeable shore reinforcements or wet reed patches for example. Otherwise the majority of the shorezones is in private hand and often lack in hygrophilous vegetation, replaced by short grass. Here often the filtering functionality of the shorezone vegetations goes missing. The stretches are mostly located between the major touristic settlements, on the northern shore as well on the southern coast (figure 36).
BASSE DEF Figure 36> SFI Category 3.
SFI Category 5 Impermeable, artificial shorelines distinguish the stretches classified in the worst category. These sections can be prevalently found in the areas interested by high population density, especially in the western basin. Reed belts are rare, wooden docks regularly present (figure 37).
BASSE DEF Figure 37> SFI Category 5.
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Management Recommandation Lake Wörthersee shows a strong anthropogenic pressure, especially those deriving from seasonal tourism. The lake is surrounded by extensive wooden areas, while agricultural surfaces almost are missing (the whole catchment area is characterized by less than 20 % of agricultural surfaces). As the nutrient input is supposed to be low, the lacking filtering functionality of almost half of the shoreline does not endanger the water quality of the lake. Domestic waste waters as well as waste waters deriving from other urban infrastructures are collected in the local drainage system and discharge outside the lake’s watershed basin.
Authors Dr. Michael Schönuber Kärntner Institut für Seenforschung Kirchengasse 43 / 2. Stock 9020 Klagenfurt am Wörthersee Sekretariat: (+43)(0) 5 0536 578 21
[email protected]
For more information Dr. Roswitha Fresner Kärntner Institut für Seenforschung Kirchengasse 43 / 2. Stock 9020 Klagenfurt am Wörthersee Sekretariat: (+43)(0) 5 0536 578 21
[email protected]
Full report available at http://www.kis.ktn.gv.at/159890_DE-KIS-Publikationen
30
A problem may derive from the increasing number of docks and piers along the Wörthersee shores. They may endanger the natural habitat structures of the local fauna, especially the fish fauna. The SFI shows that the lake shore along Lake Wörthersee has reached obstructions of a scale that affects seriously the natural functions of the bank, such as filter and buffer effects. It is therefore generally recommended to neglect interventions in intact riparian sections (rated as very good or good). Similarly, in sections with strongly modified banks, constructions (piers, marinas) should be allowed only in exceptional cases.
Millstätter See Location and Origin The second largest lake of Carinthia, the Millstätter See, has an area of 13, 28 km². As it has a depth of 141 m and a volume of 1.204,6 million m³, it’s also the deepest and water-richest lake. The main inflow of the Millstätter See is the Riegerbach with its catchment area of 188, 8 km² and an average discharge of 3.100 l/s. Besides by this the lake is also fed by a number of smaller brooks. The emissary, the Seebach, has 5.350 l/s on its average. With the increasing tourism since the 1950s a change of water quality started, which expressed in the algae bloom and the loss of the high visibility. The burdening of the lake with homemade waste water was responsible for this phenomenon. At that time the waste waters were directly led into the lake and its tributaries. With the beginning of the canalization (1968 to 1994) the re-oligotrophication process has started and with it the eye-catching algae–blooms has disappeared. The water is of excellent quality today.
The name of the lake derives from the village of Millstatt. Frequently you can hear that the name of Millstatt derives from the Latin “mille statuae” and is based on the legend of St. Domitian. He should have thrown 1.000 heathen statues into the lake, when he converted to Christianity. More probably, however, is that the name results out of the pre Slavic “Melissa”, meaning mountain brook or hill brook. The investigation for the SFI has been carried out by using videos, taken from boat and helicopter, and integrating them with aerial photographs and on-site surveys.
Results With a length of almost 27 km the shoreline of Lake Millstätter is consistently shorter than those of Lake Wörthersee, the largest Carinthian lake. As a popular bathing lake, there are several touristic settlements along its shores, especially along the northern bank line (figure 38). Most of the stretches that showed low shorezone functionality are placed there, while the steep southern shores distinguish themselves through a near-natural state and low human pressures. 25 different stretches have been identified. 6 of them showed a excellent-good state, for a overall length of over 10.000 m (or 39 %). The remaining stretches
BASSE DEF
BASSE DEF
Figure 38> SFI results for Lake Millstätter See.
Figure 39> Percentage distribution of the functionality level of Millstätter Lake.
Stretches identified
Total m
Percentages
Excellent
5
10.111
38%
Good
1
285
1%
Moderate
10
6755
25%
Poor
0
0
0%
Bad
9
9705
36%
TOTAL
25
26856
100%
SFI Value
could be distinguished by typical human pressures, resulting in residential and recreational facilities. Those anthropogenic interventions caused an artificialization of the shoreline, often using impermeable materials, and strongly impacting on the natural, hygrophilus vegetation. The poorest functionality could be encountered on a total of 9.7 km. Reed belts along the shore are rather rare because of the high slope of the shorezones.
Table 7> Summery of the SFI results.
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SFI Category 1 and 2 One third of the lake perimeter, characterized by steep, hilly surroundings especially towards south, is occupied by stretches falling in these two categories (figure 40 and 41). On the southern shores is dominating the excellent status, as human pressures result very low due to the morphology of the surrounding territory. Southwards, on the slopes of the ridge that divides the lake from the Drava valley, woodland is clearly predominant.
The only stretch with good functionality is in presence of a cliff, where the vegetation is rarefied due to natural reasons. Wet reeds formations are rare and narrow as the lake ground is rather steeply sloping.
BASSE DEF Figures 40, 41> SFI Category 1 and 2.
SFI Category 3 and 5 These categories are dominating among the numerous settlements and the traffic infrastructures along the northern shore (figure 42 and 43). Erosion protections are mostly impermeable in presence of residential and public facilities.
Private gardens and public beaches are also often completely lacking of hygrophilus vegetation. Road protection measures, made prevalently of riprap, narrow the shorezone significantly along the northern bank line. Wet reeds patches are rare.
BASSE DEF Figures 42, 43> SFI Category 3 and 5.
Management recommendation Observing the surroundings of the lake huge differences can be observed. To the south shores and hinterland are in a nearnatural state, with very low human pressures. A nutritional input to the lake from this region can be excluded. On the other hand, the remaining shores show huge anthropogenic impact on the shorezones. Residential and touristic settlements, road infrastructures and recreational spaces heavily influence its filtering functions. Nutritional input should be expected only from nearby agricultural surfaces, but actually they seem not to influence the water quality of the lake.
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The SFI shows that the lake shore on the north side of Millstätter See has reached obstructions of a scale that affects seriously the natural functions of the bank, such as filter and buffer effects. It is therefore generally recommended to neglect interventions in intact riparian sections (rated as very good or good). Similarly, in sections with strongly modified banks, constructions (piers, marinas) should be allowed only in exceptional cases.
Authors Dr. Michael Schönuber Kärntner Institut für Seenforschung Kirchengasse 43 / 2. Stock 9020 Klagenfurt am Wörthersee Sekretariat: (+43)(0) 5 0536 578 21
[email protected]
For more information Dr. Roswitha Fresner Kärntner Institut für Seenforschung Kirchengasse 43 / 2. Stock 9020 Klagenfurt am Wörthersee Sekretariat: (+43)(0) 5 0536 578 21
[email protected]
Full report available at http://www.kis.ktn.gv.at/159890_DE-KIS-Publikationen
33
Lake Bohinj Location and Origin Lake Bohinj in the largest natural lake in Slovenia. It was shaped by glacial and tectonic forces approximately 10.000 years ago. The Lake lies at 526 metres a. s. l., covers 3.28 km2 and contains 92.5 million m3 of water. Maximal depth is 45 m and the retention time of water is 4 months. The main tributary of lake Bohinj is river Savica with average discharge between 4.6 – 5.6 m3s-1. Other tributaries are smaller rapid streams and underground sources. The outflow of the Lake is river Jezernica with average discharge between 6.6 – 9.9 m3s-1 which merges with river Mostnica from the valley Voje. After the confluence the river si called Sava Bohinjka. The area of the Lake is within Triglav National Park, a designated nature protection area where nature conservation is a priority. Catchment area of the Lake covers approximately 100 km2 of mountainous and scarcely inhabited land.
Ecological state of lake Bohinj was described as “excellent” between 2006-2009 state monitoring, in 2010 however the ecological state was degraded to “good”. The reason for degradation of the ecological state estimate was lower diversity of benthic invertebrates which respond to hydro-morphological changes in littoral zone. These changes in littoral zone are caused by different natural and anthropogenic influences constantly present in lake Bohinj (ARSO, 2010). In 2011 the ecological state was again assessed as “excellent”.
Results Lake Bohinj shorezone is approximately 11.35 km long. SFI index of the Bohinj shorezone was estimated partly from the land and partly from the lake (figure 44). We divided the shorezone into 11 sections for which SFI values were estimated. SFI values for lake Bohinj range from “excellent” to “moderate” without any sections in “poor” or “bad” condition. Four sections have “excellent”, one section had “good” and six have “moderate” SFI values which reflect the human use of the shorezone of the lake.
Stretches identified
Total m
Percentages
Excellent
4
6704
59%
Good
1
500
4%
Moderate
6
4146
37%
Poor
0
0
0%
Bad
0
0
0%
TOTAL
11
11350
100%
SFI Value
Table 8> Total length and percentage of length of sections with different SFI values of lake Bohinj.
BASSE DEF Figure 44> Map of lake Bohinj SFI values for shorezone.
Excellent value of SFI for shorezone was estimated for the north shore where anthropogenic influence is very low. Entire north shore is natural and covered with forest which spreads upwards to the slopes of Pršivec and is only accessible by a footpath (figure 46).
Figure 45> Relative length of sections with different SFI values of lake Bohinj.
BASSE DEF
34 Figure 46> The north shore is natural and covered with forest.
Moderate values of SFI were estimated for the north-east part where anthropogenic influence was considerable in the past. Forest was cut to create pastures which were later abandoned. Despite the succession meadows are still open which affects the purifying function of the shorezone. There are no other human activities present which would increase the drainage of nutrients into the lake (figure 47).
BASSE DEF Figure 47> Abandoned pastures in the north-estern part of lake Bohinj.
Moderate SFI values were also calculated for the eastern shorezone which is under the influence of swimming area, village (Ribčev Laz) (figure 48 and 49), several buildings, small peer, farmland and local roads. Touristic activities are concentrated within this area and part of the shorezone is stabilized with concrete blocks. This area is flat and only a small part is covered with forest. Purifying function of this section is reduced.
BASSE DEF Figure 48, 49> E astern shore is affected by anthropogenic influence where touristic activities are concentrated.
The entire south shore is lined by a local asphalt road with relatively dense traffic in the summer months. The shore gently slopes upwards and is mostly covered with forest which is interrupted by few buildings. Entire south shorezone has excellent or good SFI values. The purifying function of the shorezone is good, however the shorezone is relatively narrow due to the road. Western shore (Ukanc) has moderate SFI values due to the touristic infrastructure (camp site) and swimming area (figure 50). Located in the immediate vicinity of the shorezone are also bungalows, hotel and farmland. Purifying function within this area is reduced.
Part of the western section is covered with occasionally flooded forest near the Savica inflow (figure 51). This section has excellent SFI value due to high uptake of nutrients from the water by the forest vegetation.
BASSE DEF Figure 50> Swimming area in the western part of lake Bohinj.
BASSE DEF Figure 51> Flooded forest with reedbeds next to the Savica inflow.
35
Management reccomandation In general the ecological state of lake Bohinj is excellent with more than half of the shorezone with excellent SFI index values which is rare among Alpine lakes. However, we noticed differences between parts of the shore under anthropogenic influence and near-natural parts. Most of the buildings are connected to the sewage system and farmland is mostly used as extensive pastures and meadows therefore nutrient seeping
into the lake is small. Additional pressure is due to swimming in non-designated areas of the shore. If tourism and degradation of the shore do not increase the state of lake Bohinj shorezone should remain excellent. Managing authorities should pay special attention to activities on the western and eastern shore where the purifying functions are already reduced.
Authors Tina Leskošek
Dr. Irena Bertoncelj
Uroš Žibrat
National Institute of Biology Večna pot 111 1000 Ljubljana Slovenia
National institut of biology Večna pot 111 1000 Ljubljana Slovenia
Nazorjeva 22 2000 Maribor Slovenia
+386 (0)59 232 700
+386 (0)59 232 700
[email protected]
[email protected]
[email protected]
For more information Tina Leskošek Nacionalni inštitut za biologijo Večna pot 111 1000 Ljubljana +386 (0)59 232 700
[email protected]
Literature Kakovost jezer v Sloveniji v letu 2010 (ARSO, 2010, http://www.arso.gov.si/vode/jezera/JEZERA_kratko_2010_MDT.pdf) Ocena stanja jezer v Sloveniji v letu 2011 (ARSO, 2011, http://www.arso.gov.si/vode/jezera/Poro%C4%8Dilo%20JEZERA%20_2011.pdf)
36
37
Conception et réalisation oct. 2012
