Analysing Information

The current work centres on analysing the information that has been collected on the Villerest reservoir. The researchers will soon receive version 1 of the GENESIS platform and will start the intensive validation of the environment, and also interfacing models to the GENESIS platform. This is a crucial step towards testing the workflow that the group needs to develop during this phase of the project and will form their primary focus for approximately the next six months.

Ongoing work

Models are being prepared to link images to the models for the displacement of cyanobacteria in the reservoir. Once the toolbox necessary to test the GENESIS platform has been received intensive experimentation will begin. The satellite cameras are being used for a number of different purposes, and although they are highly sophisticated, so far only one exploitable image on the Villerest reservoir has been received. Budgetary constraints mean only a limited quantity of images can be requested, so further in situ data will be gathered.

Protecting the Loire Valley

Parts of the Loire valley, often referred to as the Garden of France, have been classified as UNESCO World Heritage Sites, making protecting it a real priority for the authorities. In the case of GENESIS work on the Villerest reservoir this means developments further upstream on the Loire River must be taken into account. For several years Saint Etienne, which is upstream of the Villerest reservoir, had no waste water treatment plant. It is now clear that untreated waste water was transferred to the reservoir, and that it created some significant problems in terms of water quality. In June 2009 a waste water treatment plant was opened in the region; GENESIS researchers are working to assess the impact this development has had on water quality in the Villerest Reservoir.

Project Overview

Introduction

This pilot addresses the transfer of knowledge about water quality in terms of its impact on health and to achieve effective crisis management. By focussing on the monitoring of water quality, this pilot will be carried out in the context of the Water Framework Directive.

The study is being carried out at the reservoir of Villerest, on the Loire river in France. For many years, the water here has been the subject of a proliferation of the bacteria cyanobacteria, which can be toxic. Cyanobactria develop mainly in eutrophicate waters, which are rich in phosphor and secondarily in nitrogen and have weak oxygenation (notably stagnant waters). The problem is particularly acute during the summer months, as the organisms develop themselves during hotter spells of weather.

The reservoir

The Villerest reservoir is 36 kilometres long and runs from Balbigny to Villerest, two towns of Loire department. The storage volume of the reservoir ranges between 68 and 235 Mm³ and it is located downstream a 6520 km² area watershed. The dam of Villerest was originally built in 1984 to reduce the impact of the river Loire floods by managing storage volume. The second function of the dam is to support low-water period, while a third function has been developed to generate electricity through a hydroelectric power plant owned by EDF.

Context

Villerest was chosen for this pilot as a model to test the relevance of remote sensing and monitoring of cyanobacteria blooms in a large scale aquatic ecosystem, in particular because it is regularly affected by toxic cyanobacterial bloom named Microcystis aeruginosa.

Chemical structure of microcystin present in Villerest

These proliferations are difficult to monitor because of the strong heterogeneous nature of the spatial distribution of cyanobacteria. Indeed, this distribution means we will have to make multiple samples if we are to obtain a good estimation of the cyanobacteria proliferation on the whole reservoir as well as anticipate problems arising at particular points, such as a bathing area.

There are also significant temporal variations in the biomass of cyanobacteria which also makes it necessary for multiple sampling if we are to follow the evolution of the population correctly. These constraints make this monitoring process both labour intensive and costly for this pilot.

Why are we doing this here?

This bacteria causes damage of several varieties and by monitoring its proliferation, we can add to the GENESIS solution in the Single Information Space for the Environment.

The damage caused by the specific cyanobacteria found at Villerest are:

It develops on the surface and is strongly visible. This colours the water green and decreases its transparency, while it also colours the reservoir's banks by leaving an indelible mark. It also smells terrible!

• Its development disturbs the natural ecosystems. A cyanobacteria is an oxygen consumer so degrades the biomass during the bloom.

• There are both health and sanitation problems linked with toxic development due to cyanobacterial proliferation.

The reservoir eutrophication during summer period

Finally, Villerest is an excellent representative model for reservoirs with these problems with cyanobacteria and also for other large-scale aquatic ecosystems.

The state we are in

Tourism in this area is vitally important to this area of France, but it is being badly affected by this problem as the phenomenon takes place during the most intense tourist period.

The reservoir itself plays host to a number of tourist activities. There are two harbours, campsites on the lake's banks and a bathing area. The cyanobacterial proliferation causes severe problems for all this activity.

Up to this point, monitoring the reservoir water has been based on regular samplings which are analysed and, if necessary, toxins are administered. This monitoring and analysis takes place before and after the bathing season and is the responsibility of the Health and Sanitary Departmental Direction (DDASS).

Visual monitoring of the water is also carried out but is the responsibility mayor. In terms of bathing in the water, this obligation is delegated to the bathing supervisor who can forbid bathing at any time using flags of different colours.

As it stands today, there is no system in operation to circulate information about cyanobacterial presence. One bathing area has even been closed for a whole year by the responsible mayor, as he was unable to manage the situation.

This pilot offers solutions to improve the transfer of the appropriate information with the aim of more accurate forecasting and warnings

The work

The work will consist of:

• Several campaigns for multispatial sampling based on the use of a spectrofluoprobe

• The analyses of satellite imagery to determine if this approach can allow a manager to estimate the spatial distribution of the cyanbacteria biomass in the reservoir. Indeed the development of cyanobacteria is highly linked with the presence of algae. These algae are photosynthetic organisms with a green colour which mark the presence of chlorophyll. This substance allows detection by remote sensing imagery thus issuing a specific beaming. Working with these pictures, information of where the proliferation is taking place and its are expected.

In parallel with the use of remote sensing assessment for the cyanobacteria monitoring in the reservoir, this project will also work on the potential integration of this tool with the existing network of monitoring. This way we can determine a new approach that can improve the decision making process for those responsible.

Methodology

The work on this pilot site will be distributed in three parts:

• Analysis of the users' needs and the definition of detailed charges notebook

• Construction and set up of models and tools

• Experimentation and assessment

Through these three phases of the study, this pilot will improve the transfer of information, which will facilitate the decision-making process. To do this, we will build:

• A common space for sharing data and transferring the information to improve the access for all actors.
  The near real-time monitoring will improve the management of proliferation, detection and prediction of the phenomenon. A solution developed with remote sensing is going to be deployed to anticipate cyanobacteria development and thus forewarn people of the sanitary risk.

Interview with sub-project leader Marc Erlich

Marc Erlich, leader of the GENESIS fresh water quality sub-project, discusses his work at the Villerest reservoir

Located in the Loire Valley in central France, the Villerest reservoir is an important element of the regional economy, yet has been subject to sustained proliferation of cyanobacteria. Marc Erlich, the leader of the GENESIS fresh water quality sub-project based in the area, expands on their work in measuring, analysing and alerting people to the presence of toxic cyanobacteria

Patrick Truss: What are the main indicators of water quality in the Villerest reservoir?

Marc Erlich: The water quality in the lake is determined by a couple of parameters, which we are measuring within this GENESIS sub-project. Three dominant phyto-plankton groups are being measured; the concentration of cyanobacteria, of chlorophycea and diatoms in chlorophyll equivalent, which is being measured using a BBE probe, a fluorescent marker which allows us to identify the quantity of the groups in the sample.
The second measured parameter, and the most important in terms of potential impact on human health, is the concentration of toxins detrimental to humans,  micro-cystins, which are generated by cyanobacteria.
We also identify the genotype of bacteria,  this is the posterior analysis being done in the laboratory, which requires us to determine the DNA of the group of cyanobacteria in order to determine whether a defined family of the bacteria is being transmitted from one place to another in the lake.
We are also counting the phyto-plankton, in terms of the biomass of each species being captured in the sample. The total level of phytoplankton concentration (including all species), nutrients concentration and oxygen concentration determines the eutrophication level of the lake, and therefore also its general water quality status. Finally, when water surface temperature exceeds 22°C it can lead to proliferation of cyanobacteria.
In Villerest we approach the problem from the remote sensing point of view, we need spatial distribution of cyanobacteria blooms. So we cross-reference the information collected in the field with the map of distribution of the cyanobacteria blooms obtained using satellite imagery. As cyanobacteria blooms are not visible information in the signal received by the sensor of the high-resolution satellite, we need to use an intermediate level,  the identification of chlorophyll A.

PT: Are cyanobacteria mainly located near the surface of the water? Or are they distributed at various depths?

ME: The presence of cyanobacteria is strongly related to the presence of chlorophyll A in the surface water. This is within a very few centimetres of the surface. This information is quite relevant, so we don't need to deal with the deeper part of the lake where, due to the weaker reflection of the signal, technical problems regarding its representativeness may arise.
So what is being seen on the surface of the water of the lake is in some way relevant and provides sufficient information on the presence of the cyanobacteria within the algae bloom.
Cyanobacteria are distributed in both space and time. We aim to have a simple measure which will allow us to determine the path of the cyanobacteria in the water body, which is quite a long (30 km), relatively narrow lake, but with a very important dam, which closes the Loire River.
Concerning the displacement, one of the assumptions to be confirmed under GENESIS is that wind direction is a dominant factor, which influences the transfer of cyanobacteria families in the lake from one place to another. We have observed a backward effect, so in some way the cyanobacteria which were being pushed forward to the dam then, through the changing wind directions, accumulate in some hot spots of the lake, where the concentration is higher than in other places.

PT: What effect does the dam have on the quality of the water? Is stagnant water generally lower quality?

ME: Historically speaking, observations show that the quality of water in the Villerest reservoir has deteriorated since it was first established.
Many factors encourage the development of algae within the lake. One is the extensive fertilisation of surrounding land: the European Common Agricultural Policy pushed farmers to improve agricultural efficiency, which in turn caused ecological disaster in the lake.
The phosphates and nitrogen in the lake have been transmitted first from cultivated areas to the river system, and then of course to the reservoir. This process started within a couple of years of the reservoir coming into service, and it is a constant preoccupation of the users of the lake. It creates a major nuisance, iin terms of both the smell and the colour of the water. When you look at the water from space the green water is clearly dominant. In the case of Villerest the most favourable conditions for the development of cyanobacteria are stratified, stagnant, warm water.

PT: I understand the Villerest Reservoir is quite important for tourism?

ME: Yes, this is a recreational area, and as the middle course of the Loire River has been classified as a UNESCO World Heritage Site, the quality of water in the upstream part is a constant preoccupation of the local and regional authorities. There are three categories of Villerest end users: institutional (county public administration for health DASS) , the public authority for the management of the Loire River basin (EPLoire) and mayors of concerned communities, and finally professional users of the lake (fishing associations, sailing clubs, campers, etc) and the wider public.
Our approach at the Villerest Pilot to validating the GENESIS prototype is to provide the appropriate information concerning potential threats to these three groups. If the prototype is judged suitable and promising then of course it is up to the authorities to decide whether or not to pursue this approach and to establish a permanent monitoring of the cyanobacteria using technologies which we will develop.
Up to last year there was no waste water treatment plant in the agglomeration of Saint Etienne, which is in the upstream part of the Loire River, and is upstream from Villerest Reservoir. So for a couple of years untreated waste water was definitely transferred to the reservoir, and it also contributed to creating the nuisance,  that's clear.
A water treatment plant was opened in the area in June 2009. Under fresh water quality activities of GENESIS project we would also like to monitor the eventual remedial effects of putting the treatment plant into service. We want to see whether it can protect the water quality of the lake, or at least to mitigate the problem.

PT: What is the Villerest Reservoir primarily used for? Is it mainly a walking area, or do people bathe there?

ME: The lake was created as a flood protection reservoir, it prevents the inundation of historical places around the lower part of the Loire River, starting from Blois right through to Orleans.
However, Villerest reservoir is also a recreational area used for bathing, boating and fishing activities, as well as a water resource for irrigation. It is not used for drinking water.
Therefore the major concern is the contamination of land and animals by toxins, which represents an indirect risk to the population, and the exposure of bathers in the lake to toxins. For instance fish from the lake represent a risk to the consumer.

PT: How accurate are the monitoring techniques you are using? Is there some level of uncertainty?

ME: In practical terms there is some level of uncertainty for all types of measurements. For instance, the BBE probe gives a measurement of the total chlorophyll-A concentration for one group of species. This means that we need to assess the population of each species in order to compare them to the total biomass of the sample, and to estimate the cyanobacteria mass in total. Errors can be of the order of 4-10 per cent, which remains in the acceptable range.