semeau life+
Every drop counts French water is consumed the world over, making hydrological management vital in the country. Dr Patrick Lachassagne is currently investigating the role of forested land cover in the functioning of hydrosystems. Here, he discusses his methods and how they will lead to more effective environmental protection policies To begin, what are the key aims of SEMEAU Life+? Has the project encountered any challenges in realising these goals? The aim of the project is to contribute to the methodological developments required for the application of the European Water Framework Directive (WFD); one of which is a need for joint surface and groundwater modelling tools in order to help define and devise effective water management and protection policies. SEMEAU Life+ focuses on European hydrosystems where, due to the agricultural decline of recent decades, the surface of forests has increased while the surface of other land cover has decreased. Such hydrosystems are largely present across Europe; consequently an important objective of the project was to efficiently compute the quantitative hydrological role of the forest as these may evapotranspirate more than other land covers. Most existing hydrological modelling tools do not specifically take into account the hydrological role of forests. One of the challenges we encountered was integrating
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their role within hydrological modelling tools without adding too many additional parameters; generally, fewer possible parameters equates to less calibration uncertainties and thus better models. What is the premise of the modelling methodology you are developing to monitor hydrogeological processes? The modelling methodology was developed on the basis of an existing tool (MODCOU, from the Paris School of Mines), which has already been applied in numerous case studies where the joint modelling of both surface and groundwater is required (necessary in most cases). This code is quite classical in hydrological sciences, and it was our aim to work with such a tool in order to further promote the methodology. The model was adapted to correctly simulate complex volcanic hydrosystems such as Volvic but it was also, and mainly, designed to accurately simulate forest cover. With a few additional parameters, the model is able to successfully simulate forest interception
(evaporation), the temporal changes of forest transpiration, and also the temporal changes of forest root prospection depth. Consequently, the model effectively simulates the fact that deciduous trees can mobilise far more of the soil water reserves during summer than in winter. How is the project modelling climate change and forest management scenarios? It’s quite simple in principle. Each vegetation type is characterised by its Leaf Area Index (ie. the surface of the leaves for one unit of soil area) which varies depending on the tree species and the season – which is evident for the deciduous trees. We integrated this basic but essential parameter within the hydrological modelling code in order to accurately simulate the hydrological role of the forest (and other land covers such as meadows). We subsequently calibrated the hydrological code on the Volvic watershed on the basis of the prevailing land cover and climate – and also those of the past decades as we benefit from a very large set of historical data. We then simulated various changes, the most important
semeau life+ being a simulation of land cover change: what would happen if the agricultural decline and the associated forest growth continue? Are you coordinating these research efforts across national borders? Originally the project involved three French partners: Volvic, Vals-les-Bains and SaintEtienne. However, one of the actions of SEMEAU Life+ was to identify potential applications across Europe. In fact, the final conference of the project involved more than 130 participants from Europe and more from the US, Japan, India, Australia and Africa. An important result of the conference was that it gathered scientists, practitioners and stakeholders (elected representatives, technicians from central or local government, water agencies, etc.) both from the water and forest fields, and it promoted a fruitful dialogue between these two communities. Could you explain the significance and expected impact of your activities? Simulating the particular role of forests and anticipating the effects of climate and anthropogenic changes are very important in attempting to mitigate global changes, especially in regions where alterations in land cover may have an influence on the water budget (for example, by increasing evapotranspiration).We can contribute to breakthrough ideas, such as favouring specific forest stands in water stressed areas that are complementary to those already implemented.
A vital source The forested hills and mountains of Volvic, Saint-Etienne and Vals-lesBains in south central France are home to hydrosystems and forested areas. These are key to informing the development of a new transferable methodology for the total modelling of a water body, including its forested surface. The SEMEAU Life+ project is unlocking their potential The preservation of quality water resources has long been recognised as a global issue of fundamental importance. In areas such as the Volvic impluvium (the watershed of the Volvic natural mineral water located in the Auvergne regional volcano park in France) substantial economic interests are implicated and protection policies have long been established in the interest of sustainable quality. However, as understanding of hydrosystems and the role of the forest has grown, existing policies that have safeguarded against factors such as agriculture and villages waste water had to be adapted specifically to address the effects of forest growth. In 2000, in response to anxiety over the state of the Earth’s waters, the European Commission initiated the European Water Framework Directive (WFD) with the aim of protecting water sources and cleaning up those suffering as a result of anthropogenic contamination. Dr Patrick Lachassagne, Head of the Environment and Water Resources Division at Danone Waters, France, has been managing a four-year collaborative project operating across several pilot sites in France. Now nearing its end, the SEMEAU Life+ project has been collecting data from its activities in Volvic, Vals-les-Bains and Saint-Etienne in order to produce a tool for modelling surface water bodies and groundwater, and the role of forest at basin scale.
Hydro simulations As a researcher for Danone Waters France, Lachassagne heads the SEMEAU Life+ project technical component at the Volvic site in Auvergne, developing research projects in partnership with scientists from the Paris and Saint-Etienne Schools of Mines, the University of Clermont-Ferrand and Tours, and the French Geological Survey, among others, to help improve the industry’s knowledge about the hydrological structure and functioning of their
springs. In this respect, this highly forested watershed of Volvic was chosen as the principal beneficiary of the SEMEAU Life+ project but their goals are not distinct from the project itself as a key element of the modelling tool is its transferability. Its success, therefore, lies in its potential for future application in regions beyond the Massif Central. The Volvic impluvium, which comprises an area of 38 km2 and includes the iconic Puy de Dôme, has been a vital source of data for the project, not least because of the many past quantitative and qualitative studies that it has been subject to and its similarities with an estimated third of European territory. In addition to measuring the dynamics of a complex volcanic hydrosystem, researchers are also adapting the modelling tool to take into account potential evapotranspiration from forest cover to determine its contribution to water sources. By simulating the presence of conservative elements in water such as water isotopes, the project’s progress can be traced and effectively mapped out. The simulation of these parameters has enabled the Volvic team to validate the calibration of the hydrodynamic model they produced; an essential part of the tool itself. Comprising five computational modules, the SEMEAU Life+ modelling tool measures the potential evapotranspiration of forests; runoff – the transfer of water in the unsaturated zone; the underground flow from the bottom of the unsaturated zone to the paleovalleys; and the saturated flow once the water reaches the heart of the paleovalleys. The model has already generated success for Lachassagne and his colleagues. Notable findings include: • A 1 per cent increase of the Volvic impluvium forested areas would yield a 0.2 per cent decrease of the total water discharge at the outlet of the watershed • Converting coniferous stands to deciduous trees (about 15 per cent of the actual forested surface of the impluvium) would lead to approximately a 9 per cent increase in the total water discharge at the outlet of the watershed • Totally converting the deciduous stands to coniferous ones would decrease the same discharge by 85 per cent
The Vals-les-Bains ‘Geyser’ periodic spring
As knowledge of the forest’s role in hydrosystems grows, there are more opportunities to implement protection policies that extend from agriculture to forest management.
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SEMEAU LIFE+ OBJECTIVES • To develop a methodology for surface and groundwater body modelling, integrating the hydrological behaviour of forested areas, at the scale of the catchment which represents the relevant scale in terms of water resource management and protection • To define, in liaison with the local stakeholders, forest management scenarios of the areas concerned, integrating water resource protection and local economic development both in the current climate conditions as well as those prevailing in the future, incorporating climate change impacts • To conduct a set of demonstrative pilot actions relating forest management with water resource protection
partners Société des Eaux de Volvic (Danone group) SITHERE – Vals les Bains Ville de Saint Etienne
FUNDING LIFE+ Environment programme
CONTACT Dr Patrick Lachassagne Head of Environment and Water Resources Evian Volvic World Sources – Danone Waters BP 87 – 11 Avenue Général Dupas 74503 Evian-les-Bains Cedex France T +33 6 03 85 15 71 T +33 4 50 84 86 25 E
[email protected] www.life-semeau.eu DR PATRICK LACHASSAGNE obtained his PhD in Quantitative Hydrology and Hydrogeology from the Paris School of Mines in 1989. He earned a Professoral degree (Habilitation à Diriger des Recherches) from Montpellier 2 University in 2008. After 20 years at BRGM, the French Geological Survey, from 2008 to date, Lachassagne has occupied the position of Head of Environment and Water Resources and is in charge of research activities, new water resources, operational management and the protection of Evian, Volvic, Badoit and La Salvetat.
A model for management
Educational trail – Vals-les-Bains
Although it is a marked achievement, the success of the SEMEAU Life+ project is not solely bound to modelling the operation of hydrosystems. WFD emphasises the conservation of quality water sources and the modelling tool helps enable this by increasing global understanding of hydrosystems. However, it is the participation of the communities at the water’s source that is most crucial to the completion of its goals. The project’s end-users are integral to its continued success which is why a large part of SEMEAU Life+ has focused on developing a system where by ownership is transferred to them. An essential component of the study was to involve local inhabitants in land management. In order to aid communities in implementing environmental protection policies, particularly with regard to forests, the pilot sites extended beyond Volvic’s catchment, encompassing those of SaintEtienne and Vals-les-Bains. Situated in the Massif Central, Saint-Etienne is an ideal test site due to the proximity of the Furan watershed – a forested tributary of the Loire – which displays increased levels of phosphates. In particularly aggravated circumstances, this can lead to eutrophication which can result in phytoplankton blooms that upset the balance of the local ecosystem. Studying the Furan enabled the identification of the sources of these phosphates and lead to the implementation of preventative measures. The spa town of Vals-les-Bains, which lies in the Ardèche region of France, was chosen for its numerous natural mineral springs that are a part of the Volane watershed. Here, SEMEAU Life+ has been specifically concerned with community actions beseeching involvement with the preservation of water sources. “To achieve this the project created an educational trail that passes through various different water-based features of the forested landscape in order that both local people and tourists, children and adults, can appropriate the main
principles of water management,” explains Jean-FranÇois Terrisse from SITHERE – the SEMEAU beneficiary in Vals.
Win-win Perhaps one of the most important outcomes of the project has been how the principles of water protection policies developed at Volvic can be applied to other areas through the twoway benefits of their application. Their main principle is founded on the advantages of water abstraction at the spring, which is used upstream on their catchment both to favour the protection of the water resource and also to support local development on the catchment. In France, there is a tax, for example, on each bottle of Volvic sold that, through the Volvic protection policies, makes its way back to the source’s impluvium. In the frame of SEMEAU, these benefits favour water protection and the development of the income of private forested land owners. According to Lachassagne, the main principles are “downstream/upstream redistribution, and win-win policies”. Providing education and incentives for the communities at the source will ensure not only the continued preservation of quality water but also, as in Saint-Etienne, encourage the treatment of contaminated sources. With the modelling tool especially adapted to a variety of hydrological scenarios and land management, and as growing interest in countries outside of Europe indicates, its application is likely to benefit many other communities with a quality water source.
Natural mineral water bottling company (S E M VALS), Vals-les-Bains
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