Environmental Hydraulics

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2 PROCEEDINGS OF THE 6TH INTERNATIONAL SYMPOSIUM ON ENVIRONMENTAL HYDRAULICS, ATHENS, GREECE, JUNE 2010 Environmental Hydraulics Editors George C. Christodoulou & Anastasios I. Stamou National Technical University of Athens, Greece VOLUME 1

3 Environmental Hydraulics Christodoulou & Stamou (eds) 2010 Taylor & Francis Group, London, ISBN Types of artificial water bodies in the Aegean islands (Greece), their environmental impact and potential value for biodiversity N.M. Georgiadis, K. Paragamian, T. Giannakakis, D. Poursanidis & G. Catsadorakis WWF Greece, Athens, Greece ABSTRACT: Since 2004 WWF Greece has started a survey of the poorly known wetlands of the Greek islands, aiming to assess their status and ensure their conservation. We identified 685 wetlands larger than 0.1 ha at 67 islands of the Aegean archipelago. Among them there are also artificial water bodies, created by hydraulic constructions, as well as by mining works and excavations for aggregates. Lately, the number of these is increasing in order to meet the large fresh water needs of these islands. We located 186 artificial water bodies of 8 types, in 26 islands covering a total area of 918 ha. In this paper we assess the several types of water bodies as wildlife habitats; we discuss their environmental significance for wildlife, as well as their impact upon the downstream natural wetlands; and we propose the most ecologically sound types from a conservation-of-biodiversity point of view. It is not advisable to construct more dams. Off-stream reservoirs with or without buried membrane liming are more ecologically sound and can better serve wildlife needs. 1 INTRODUCTION The Aegean archipelago is a hotspot for the biodiversity and endemism of Greece and Europe (Sfenthourakis & Legakis 2001). One of its many noteworthy features is the presence of numerous small wetlands, of great importance for the geographical continuity, diversity and sustainability of life on the islands of theaegean (Paragamian & Catsadorakis 2007, Paragamian 2009). They support numerous endemic and rare species and most of them are important stop over sites for millions of migratory birds each year (UNDP 1999). Furthermore, nearly all island wetlands are of great value for the islanders, as they contribute to water adequacy, protect coastal agricultural land from salinization, and participate in the processes of beach creation, while increasing landscape mosaics (Catsadorakis & Paragamian 2007). In a region that is among the driest of the Mediterranean, they also provide benefits connected mainly with groundwater recharge and sediment, pollution and nutrient retention. The economic value of all the above is large but difficult to estimate and depend upon functioning freshwater ecosystems (Smith & Darwall 2006). However, many of the natural wetlands of these islands are being degraded daily by various anthropogenic activities (rubble and garbage dumping, pollution, drainage, overexploitation, drillings, upstream water retention etc.) (Tsiouris & Gerakis 1991, Catsadorakis & Paragamian 2007, Paragamian 2009). In most of the Aegean islands, water resources do not suffice to cover the increasing demand, mainly due to the rapid growth of tourism in recent decades (Voivontasa et al. 2003, De Stefano 2004) and by unsustainable irrigation practices. Despite the (limited) use of solutions such as desalination, in recent years (Kechagias & Katsifarakis 2004, Manolakos 2008), most of the needed water is either transported by ship (a costly alternative) or stored in artificial reservoirs. Water resources management in Greece currently faces significant challenges. The rate of implementation of the water frame directive (WFD) 2000/60/EC (which has been incorporated in the national legislation with law N. 2339/03) is not satisfactory, while a number of chronic problems have not found a solution, yet (Gikas & Angelakis 2009). During the last two decades a sharp increase in the construction of reservoirs is observed in the Aegean islands, which are the major works on the islands with respect to water resource management. Most of them are planned and managed almost exclusively as technical basins. Both their potential environmental significance and impacts are practically neglected. The present paper presents the main findings regarding the number, distribution and types of the artificial water bodies surveyed and discusses the potential of the artificial water bodies as habitats for wildlife, their potential value and their impacts upon the downstream natural estuarine wetlands. 1137

4 2 METHODS All island wetlands larger than 0.1 ha (both natural and artificial) were located through: a. Literature scan, b. Answers to questionnaires sent to over 200 local and regional authorities, individual scientists and NGOs, and c. Examination of satellite images. Field surveys were carried out to verify the occurrence and document the type and area of each wetland and provide a basic assessment of their ecological and hydrological significance as well as their conservation status. Data were collected in accordance to MedWet wetland database and were entered in an adapted Microsoft Access database and a Geodatabase. To evaluate the water bodies biological significance a score was given to each one of them, based on biological indices such as the presence of certain animal and plant species, the overall biodiversity and endemism, the occurrence of invasive species and the capacity of the artificial water body to maintain life. Additionally, literature review and aerial and satellite images were used to investigate the impact of different types of artificial reservoirs to the downstream estuarine wetlands. 3 RESULTS 3.1 Inventory of artificial water bodies We located 186 artificial water bodies, larger than 0.1 ha situated in 26 islands and covering a total area of 918 ha. Of these, 50% (both in number and surface area) are found in Crete, followed by other large islands as Evia (23/133.8 ha), Lesvos (10/50.4 ha) and Rhodes (5/64.8 ha). These were classified into eight different types according to their construction and position: i. Dam lakes (22 in 13 islands, total area 582 ha), located mostly in Crete (7/360 ha) and South Aegean region (144 ha mainly in Mykonos and Rhodes), and less in the North Aegean region (78 ha), ii. Gravel/brick/clay/borrow pits (31 in 8 islands, 34.5 ha), located mostly in Evia, Crete and Lesvos, iii. River barrier pools (5 all in Crete, 5.9 ha), iv. Membrane covered reservoirs (35 in 13 islands, 108 ha), located mostly in Crete, Chios and Lesvos, v. Reservoirs with burried membrane or no membrane (45 in 6 islands, 52 ha), mainly located in Crete, Kos, Rhodes, Samos and Chios. vi. Concrete reservoirs (14 in 4 islands, most of them in Crete), covering 3.5 ha, vii. Mine pools (29 in 4 islands), covering 128 ha located mostly in Evia and Milos and viii. Wastewater treatment marshes (5, all in Crete, 5.9 ha). Another 50 hydraulic projects have been planned for the coming years. Among them, 31 are dams and the other 19 are mostly membrane covered reservoirs. More than half of the hydraulic projects will be built on small islands of the Cyclades (19) and the Dodecanese (7) (Anonymous 2008a, Anonymous 2008b, Greek Commission on Large Dams 2009). Water inputs in the island artificial water bodies take place in 5 different ways: 70 are fed by streams of temporary or permanent flow, 46 are fed by surface flow, 14 are fed by karstic springs, while marshes of waste water treatments are fed by sewage waters. Only 3 are fed by water drawn of drilled wells while for 46 we were unable to identify the origin of water inputs. 3.2 The artificial water bodies as wildlife habitats The creation of water bodies modifies the environmental qualities of the flooded area and of a broader area around it, depending mainly on local climate, soils and topography. Bank slope, depth and water level fluctuation in combination with age, play a significant role in the aquatic characteristics in the artificial wetlands (Dimalexis et al. 2005). The biological indices we used showed that only 11% of the Aegean islands artificial water bodies have high biological value, 19% medium biological value, 31% low, 21% were found to have neutral functions, while 18% were found to have negative effects. All marshes for wastewater treatment were found to be of high biological significance, followed by 40% of the river barriers 1138

5 Figure 1. Biological significance of Aegean s island artificial water bodies. pools and 27% of dam-lakes (Fig. 1). In the cases of the membrane covered reservoirs as well as in the mining pools with steep rocky slopes, aquatic vegetation is absent or minimal. Furthermore, the majority of the membrane covered reservoirs have mostly negative value as they act as pitfall-traps for many animals that approach to make use of water, since, due to the slippery substrate, they cannot climb back to land and they drown. Reservoirs with buried membranes or no membranes are much more favourable for vegetation growth and support more wildlife. The same applies to small ponds dug in earth to store irrigation water for farmlands, have smaller depths and bank gradients, which in combination with stable water levels, result in the development of wetland vegetation and the colonization of the system by aquatic species. 3.3 The effect of artificial wetlands on the downstream natural wetlands In most of the Environmental Impact Studies (EIS) and approved Environmental Terms (ET) of hydraulic works in the islands, there is no data related to the minimum water flow (known as: ecological flow), which is needed for the maintenance of the downstream ecosystems. Only in 7 out of the 26 approved ET that we were able to collect, there are clear references to ecological flow but without any specification on quantitative data or methods of measurement and application. The supply of fresh water and sediments is directly affected by upstream artificial reservoirs in 22 Aegean island natural wetlands (Table 1), while another 17 natural wetlands are expected to be affected by hydraulic projects to be built over the next few years (Table 2). For all these wetlands a minimum supply of fresh water flow and of some sediment transport should be ensured. 3.4 The Livadi marsh in Serifos Island: a case study. The Livadi marsh in the island of Serifos was a typical small mouth of an intermittently flowing stream. During heavy rainfall, the wider area around the mouth was flooded. Thus, apart from the aquatic vegetation on the stream banks and mouth, the broader area was transformed to a brackish temporary marsh, part of which was cultivated with non-irrigated crops during the summer period. The above condition changed after the construction of the Steno Dam, almost 1.5 km upstream from the marsh, which traps more than 2/3 of the watershed s run off. The dam was completed in Since 1999 the water flow downstream decreased to almost zero, as there was no provision for ecological flow or for any water flow at all. As few water and no sediments were reaching the stream mouth, the area with aquatic vegetation shrunk and flooding ceased. Those facilitated secondary anthropogenic interventions which resulted in the destruction of the small wetland. As can be seen from aerial images (Figure 2) changes in the land cover-use of the area close to the stream bank but also in the riverbed itself are apparent. In 1983, only a few buildings stood close to the stream bank, whilst a clear water line and wetland vegetation in both sides of the stream occurred. In 2004, five years after the reduction of fresh water flow caused by the dam, the same area was totally altered. 1139

6 Table 1. Natural estuarine wetlands that were found to be impacted by the effects of upstream reservoirs. WWF WWF CODE NAME ISLAND CODE NAME ISLAND AMO001 Katapola marsh Amorgos LEM012 Estuary of Chandrias Limnos AST003 Kampos or Livadi Astypalaia LER001 Agia Kioura marsh Leros CHI025 Estuary of Partheni Chios LES028 Skala Eressou Lesvos CHI005 Komi marsh Chios LES081 Estuary of Mithimna Lesvos IKA001 Estuary of Halaris Ikaria MYK001 Estuary of Panormos Mykonos IKA003 Estuary of Mirsonas Ikaria MYK004 Estuary of Phoko Mykonos IOS005 Estuary of Mylopotas Ios NAX016 Estuary of Phaneromeni Naxos KRI091 Estuary of Anapodaris Crete ROD003 Estuary of Gadouras Rhodes KRI135 Geropotamos (estruary) Crete ROD028 Estuary of Sianitis Rhodes KRI142 Estuary of Platane Crete SER005 Livadi marsh Serifos KRI252 Mpramianos (esturary) Crete THA003 Estuary of Maries Thasos Table 2. Natural estuarine wetlands that will be likely affected by hydraulic projects under construction. WWF WWF CODE NAME ISLAND CODE NAME ISLAND AND003 Ateni lake Andros NAX006 Estuary of Skoylikaria Naxos CHI001 Limnos or Marmari marsh Chios PAR004 Molos marsh Paros CHI003 Estuary of Kokala Chios PSR001 Marsh of Psara Psara KRI203 Tavronitis estuary -marsh Crete ROD007 Estuary of Lardos Rhodes LES020 Estuary of Tsiknias Lesvos ROD008 Estuary of Asklipios Rhodes LES022 Pharmakies Lesvos SAM010 Megalo Rema Samos LES038 Almyropotamos (Vatera) Lesvos SAM011 Fourniotikos (estuary) Samos LES054 Estuary of Vourko Lesvos TIN002 Kolympithra Tinos MIL011 Estuary of Agios Ioannis Milos Figure 2. Aerial photos of Livadi marsh on the island of Serifos, Cyclades, Greece in 1983 and There was no vegetation on both sides, more buildings have been constructed and the riverbed has been covered with concrete and used as a road. This is a typical case of the succession of secondary interventions taking place following the arrest of water flowing to the river mouth by retention upstream. 4 DISCUSSION AND CONCLUSIONS The geographic distribution of artificial reservoirs is mainly related to the adequacy of water resources, and intra-annual fluctuation of water demand. There are greater numbers in the arid and highly visited Cyclades islands, but also in the larger Aegean islands, where permanent populations 1140

7 are larger and water demand is higher. Most of them are planned and managed almost exclusively as technical basins. Both their potential environmental significance and impacts are practically neglected. In all hydraulic works, appropriate measures to support biodiversity and mitigate the impact to the remaining natural aquatic system should be taken. Such measures should be designed having in mind the proper function of the downstream wetland ecosystems but also the multiple functions that an artificial water body can play. This is also the case for interventions that can be made to existing artificial reservoirs by ensuring an ecological water flow for the downstream ecosystems and by creating artificial wetland(s) in all or part of the reservoir or in proximity to it. However, it should be stressed that in any case, an artificial wetland cannot replace the ecological functions of a natural wetland that has been degraded. It can offset some losses, but in no case, it can create an equivalent ecosystem, in terms of biological quality and ecological functioning. Additionally, we must consider that in many cases, artificial reservoirs are those responsible for the degradation of natural wetlands that depend on the basin of each project. The retention of a stream s or river s flowing water, at some point above the estuary, alters the basic attributes on the whole water system. These differentiations are caused primarily due to lower amounts of water flow downstream but also other factors are involved. A series of many hydrologic and hydraulic parameters compose the structure and function of wetland ecosystems and therefore their water needs. In these parameters we should definitely consider the characteristics associated with sediments and their transportation from upstream to downstream plains and estuaries. Thus, it should be noted that the minimum water flow (ecological flow) is not the only parameter in order to ensure the preexisting structure of downstream wetland ecosystems that are influenced by hydraulic works. In other words, it is assumed that the construction of any hydraulic work changes the natural distribution and synchronization of flows, resulting in a change of sediment and nutrient regimes, temperature and other physicochemical characteristics of water, thus changing the structure of wetland ecosystems (Kingsford 2000, World Resources Institute 2004). However, the minimum water flow from an artificial reservoir to downstream ecosystems is clearly the most important parameter for maintaining aquatic characteristics in downstream areas and therefore has been studied more than all the other parameters. Thus, although most of the island coastal wetlands depend also on groundwater and sea-water, the fresh surface water from the linked streams, which, in most of the cases, are flowing a few times a year, is still very important for their existence. In the cases of Katapola marsh (Amorgos isl.), the estuary of Mylopotas (Ios isl.), Livadi marsh (Serifos isl.) and the estuary of Mpramianos (Crete isl.) it is known that the retention of water and sediments caused by upstream dams have led to a reduction in wetland area, which allowed for secondary anthropogenic interventions (rubble, extension of croplands, building, etc.) resulting in total destruction of these degraded natural wetlands. Such phenomena of degradation are evident in almost all natural wetlands connected to an upstream artificial water body. For all the above reasons it is proposed that the construction of large hydraulic projects, especially dams, should be stopped in the islands. Instead, several smaller off-stream reservoirs with buriedmembrane lining or no membrane at all, which does not heavily affect the natural water bodies (river basin, watercourse, estuary) is considered to be a better solution. Additionally, the construction of small river barriers as high as possible in the basin, for the enrichment of groundwater, is still a solution that can help save water without significantly affecting the natural water systems. REFERENCES Anonymous. 2008a. Table of constructed and under construction hydraulic works. Association of Hydraulic Engineering Consultants. Published report on the Internet: (In Greek.). Anonymous. 2008b. Table of constructed and under construction hydraulic works by the ministry. Hellenic Ministry of Rural Development and Food. Published report on the Internet: (In Greek.). Catsadorakis, G. & Paragamian, K Inventory of the wetlands of the Aegean Islands: Identity, ecological status and threats. 392pp. Athens: World Wide Fund for Nature WWF Greece (In Greek). De Stefano, L Freshwater and Tourism in the Mediterranean. WWF Mediterranean Programme. Rome, Italy. (Unpublished report). Dimalexis, A., Spyridaki, E., Dretakis, M. & Nikolakakis, M Good Practice Guide for the design and management of reservoirs in order to achieve multiple functions. Life00 ENV/GR/ Natural History Museum of Crete. University of Crete. Heraklion (In Greek.). 1141

8 Gikas, P. & Angelakis, A. N Water resources management in Crete and in the Aegean Islands, with emphasis on the utilization of non-conventional water sources. Desaliniation 248: Greek Commission on Large Dams Table for constructed and under construction large dams. Published report on the Internet: (In Greek.). Kechagias, E. & Katsifarakis, K. L Planning water resources management in small islands, the case of Kalymnos, Greece. Water, Air, and Soil Pollution: Focus 4: C 2004 Kluwer Academic Publishers. Printed in The Netherlands. Kingsford, R.T Ecological impacts of dams, water diversions and river management on floodplain wetlands in Australia. Austral Ecology 25: pp. Manolakos, D Desalination Systems in the Greek islands. Paper presented in the workshop: solutions for the future organized by Korthi Municipality, UM of N. Cyclades. 5/10/2008 Andros. (In Greek.). Paragamian, K The island wetlands of Greece. In Efthymiopoulos, I. & Modinos, M. (editors) The Eco-nomy of Water: Ellinika Grammata/DIPE. Paragamian, K. & Catsadorakis, G Inventory of the Aegean islands wetlands: A two-year WWF greece s project. Proceedings of the 3rd Conference of Hellenic Ecological Society and Hellenic Zoological Society Ecology and Conservation of Biodiversity. pp (In Greek). Sfenthourakis S. and A. Legakis Hotspots of endemic terrestrial invertebrates in southern Greece. Biodiversity and Conservation 10: Smith, K. G. & Darwall, W.R.T The Status and Distribution of Freshwater Fish Endemic to the Mediterranean Basin. IUCN, Gland, Switzerland and Cambridge, UK. Tsiouris, S. & Gerakis, A. P Wetlands of Greece. Value Lessons Protection. Aristotle University of Thessaloniki WWF Greece. (In Greek.). United Nations Development Programme Conservation of Wetland and Coastal Ecosystems in the Mediterranean Region. Medwetcoast. Regional Project Document. UNDP, Global Environment Facility. Voivontasa, D., Arampatzis, G., Manoli, E., Karavitis, C. & Assimacopoulos, D Water supply modeling towards sustainable environmental management in small islands: the case of Paros, Greece. Desalination 156 (2003) pp. World Resources Institute Rivers at Risk. Dams and the future of freshwater initiatives. Dam right, WWF Dams Initiative. 1142

Blocking Sea Intrusion in Brackish Karstic Springs

European Water 1/2: 17-23, 3. 3 E.W. Publications Blocking Sea Intrusion in Brackish Karstic Springs The Case of Almiros Spring at Heraklion Crete, Greece A. Maramathas, Z. Maroulis, D. Marinos-Kouris