2017-09-13 7 WATER SAVING CHALLENGE Field Study 2: Houat Ronan le Goaster at the main well (Forage 5”) on Houat 1 (19) WATER SAVING CHALLENGE Christian Pleijel [email protected] Tel +358-457-342 88 25 FIELD STUDY: HOUAT Content 1 Summary 2 2 Introduction 3 The assignment The client Study objects The three levels of an island Methodology 3 The water of the island 6 Location Geology Hydrology and climate Vegetation 4 The water of the islanders 9 Human pressure Virtual distance Water consumption 5 The water of the community 10 Governance Water procurement Wastewater Water quality Cost and taxes Future plans 6 Water saving 13 Benchmark #1 Benchmark #2 7 References 17 2 (19) WATER SAVING CHALLENGE FEL! DET GÅR INRTE ATT HITTA NÅGON REFERENSKÄLLA. FIELD STUDY: HOUAT 1 Summary Houat is a 3 km2 island outside Brittany in France. It has a resident population of 250 in- habitants but, given the large number of summer residents (3,000) and visitors 100,000), the human pressure on the islands' freshwater system (as well as energy distribution, sewage and waste recuperation and treatment, roads, ports, telephones, internet, trans- ports, postal services, healthcare and fire brigade) is equivalent to a population of 554 persons and the need for water is 22,5 million litres for 2015 and 23,3 millon litres for 2016, according to SAUR. Water procurement, distribution and management on Houat is organised in cooperation with the mainland municipalities in a joint company. Although being highly competent, it is not the company’s primary interest to save, but to sell water. The legal framework PLU puts restrictions on the citizens and the landowners, but not on water management. Resi- dents’ water consumption is half of the island’s total needs but when calculating the amounts needed from a consumer’s perspective, it does not meet the producer’s perspec- tive. The will, efforts and a mindset for saving water on Houat were mainly be found with the mayor of Houat, Mme Andrée Vielvoye, who pushes the issue in her private life as well as on the municipal level through Houat’s PLU (Plan Local d’Urbanisme), which stipulates that all new buildings are to be built with a rainwater reservoir, prohibits swimming pools and private drillings. 3 (19) WATER SAVING CHALLENGE FIELD STUDY: HOUAT 2 Introduction 2.1 The assignment The Houat study is part of an assignment to search for, find, describe and share good ex- amples of water saving practices on eight European islands, islands who do not solve wa- ter scarcity just by bringing more water through pipelines, desalination plants and tank- ers, but are making efforts to save water. The project is looking for best practices within four areas of water saving actions: 1 Training: Information, good examples, schooling, campaigns, understanding that water has different qualities which can be used for different purposes. 2 Engineering: Technologies for reducing water consumption in households (water taps, showerheads, toilet sinks etc), for reducing leakages in mains and pipes, for more effi- cient desalination/reverse osmosis processes, treatment of wastewater etc. 3 Billing: Differentiated pricing of (municipal) water that lead to water saving. 4 Cutting: Switching off the (municipal) water: mostly for shorter periods of time. Obstacles to save water can be found in governance (water saving is not a political issue), regulations, cost, taxes and financial obstacles (the water company does not earn money by saving water), no ‘sense of urgency’, sustainability indicators are underdeveloped or inexistent, management (saving is not an objective), human behaviour, business threats (water saving might ruin the visitors’ experiences and damage the island’s brand), tech- nology and over-capacity (the island has a system which procures more water than the island needs, even in peaks). 2.2 The client The assignment has been given to the Royal Institute of Technology (KTH) in Stockholm by MEP Tonino Picula from Croatia, the Hellenic Small Islands Network, l'Association des îles du Ponant, the Irish Islands Federation/Comhdháil Oileáin na hÉireann and ESIN – the European Small Islands Federation. 2.3 Study objects Eight islands are included in the project: Tilos and Ithaca in Greece, Lastovo and Vis in Croatia, Sein and Houat in France, Inisheer and Cape Clear in Ireland. 4 (19) WATER SAVING CHALLENGE FEL! DET GÅR INRTE ATT HITTA NÅGON REFERENSKÄLLA. FIELD STUDY: HOUAT Figure 1. The eight islands in the study They have been chosen because (a) they all have a scarcity of freshwater, (b) they repre- sent different sizes, seas, hydrogeology, climate, size of population and remoteness, (c) they have what seems to be interesting solutions for saving water, and (d) they have been in previous contact with us which makes it easy to obtain true data within a limited time and budget. 2.4 The three levels of an island To understand the freshwater situation of an island, the whole island must be observed (not just the technologies). We describe three interlinked levels: a The water of the island This is the basic geophysical system level which encompasses the physical geographical conditions on the island no matter if people live there or not: geology, oceans, skies, hydrology, meteorology, flora and fauna – the physical landscape. b The water of the islanders At the next level, humans move in and make their human footprints: they build houses and villages, till the soil and water, eat, drink, walk, arrange their social life with chil- dren, schools, elderly care, health care and security – the cultural landscape. c The water of the community 5 (19) WATER SAVING CHALLENGE FIELD STUDY: HOUAT At the top level, the humans build a common infrastructure of roads, water, sewer, tel- ephone, broadband, fossil and renewable energy sources, ports and ships. Water is produced, distributed, managed, financed and administrated – the technical landscape. 2.5 Methodology Data about the islands has been collected through desktop research and field studies, dur- ing which we made make semi-structured interviews with politicians, technicians and citizens, investigated technical installations, took part of documents, plans, studies, maps and earlier research. This field study on Houat was undertaken by Christian Pleijel and Maxime Bredin on 20th and 21st of april, 2017, under supervision of professor Anders Nordström from the Univer- sity of Stockholm and professor Louis Brigand from the University of Brest (Maxime Bre- din is one of professor Brigand's students). We are most thankful to the mayor of Houat Mme le Maire Andrée Vielvoye and water consultant Ronan Le Goaster from Eau du Mor- bihan for their time and efforts to answer all our questions and guiding us around the is- land. Figure 2. Ronan Le Goaster, Maxime Bredin. Andrée Vielvoye et Christian Pleijel 6 (19) WATER SAVING CHALLENGE FEL! DET GÅR INRTE ATT HITTA NÅGON REFERENSKÄLLA. FIELD STUDY: HOUAT 3 The water of the island Figure 3. Houat 3.1 Location Houat (Enez Houad in Breton) is a French island in the Atlantic Ocean, off the south coast of Brittany in the department of Morbihan. It is located, along with two other major is- lands, in the entrance to the Baie de Quiberon. The surface of Houat is 2,9 km2. The island is 5 km long and 1.5 km at the widest. It is mostly granite cliffs except for a long beach lined with dunes on the eastern coast. Figure 4: Hoat on a sea chart 7 (19) WATER SAVING CHALLENGE FIELD STUDY: HOUAT Figure 6: Geology of Houat, from… 3.2 Geology Houat is a massive of gneiss and granite in slight slope. There are sand dunes in the north- east and the south east, the rest of the coast is steep from 14 to 29 meters, cut by ravines with sandy beaches. Inside the islands, the terrain is mostly flat between 25 and 28 me- ters. 3.3 Hydrology and climate West coast climate with relatively large annual precipitation. The three summer months have little rainfall which makes the island a nice holiday island. The average rainfall for the years 1993-2002 on Houat is 910 mm per year and the total of water falling on the island 750,000 m3 per year 1. The variations in rainfall are big, see the table below. Groundwater recharge is about 480 mm in most parts of the island (ref 4). The same reference indicates that the runoff is about 220 mm and the groundwater for- mation is only 260 mm. The thin soil cover on a large part of the island's surface, as well as the bedrock's thin cracks, hamper infiltration in the bedrock. Groundwater can be the source of the island's total water use. Caution to drill for deep wells should be observed to prevent saltwater penetration in the wells. The bedrock has varying size and amounts of cracks, which gives a wide variety of possibilities for outlets across the island. 1 Étude hydrogéologique Houat 2004, page 21 8 (19) WATER SAVING CHALLENGE FEL! DET GÅR INRTE ATT HITTA NÅGON REFERENSKÄLLA. FIELD STUDY: HOUAT Table 1: Rainfall on Houat 1993-2002, source Météo France sur la station de l’île d’Houat 3.4 Vegetation The top of the island plateau was practiced until the 1960s; today, pastures have given way to brushwood (gorse, ferns, brambles). 9 (19) WATER SAVING CHALLENGE FIELD STUDY: HOUAT 4 The water of the islanders For a general introduction to the island, its culture, history and society, see http://www.mairiedehouat.fr, http://www.ina.fr/video/CAF93010642/l-ile-de-houat- video.html and http://www.iles-du-ponant.com/visitons-nos-iles/ile-de-houat.