Studies on aquatic environments include an ecological diagnosis of the lake, an analysis of the phosphorus balance at the watershed level, as well as the characterization of streams. These studies are essential to gather the knowledge necessary for harmonious and sustainable development that minimizes the impact of human activity on aquatic systems.
Study of Lakes
The health of our lakes has a direct impact on the environment, but it also has an influence on the quality of life of a region’s shoreline residents and on the strength of the economy. To address the various problems (aging, contamination, coastal erosion, usage conflict, etc.) that can occur, Groupe Hémisphères:
- consolidates and analyzes the available knowledge;
- masters the different ecological diagnosis evaluation tools (physico-chemical profile, bathymetric or morphometric surveys, turnover rate, biophysical description of the watershed, moisture balance, as well as the characterization of banks, tributaries, aquatic vegetation, etc.);
- applies the Protection Policy for Lakeshores, Riverbanks, Littoral Zones and Floodplains;
- evaluates the lake’s health using proven models and other evaluation parameters collected in the field;
- identifies usage-related issues;
- conceives and implements a lake management plan, an action plan and corrective measures;
- prepares and explains scientific concepts in a clear, concise manner;
- implements an information and education program on the environment;
- searches for partners and financing, and negotiates conservation agreements.
Modelling Phosphorus Retention in Lakes
A phosphorus balance assessment includes a comprehensive analysis of the watershed’s soil use which makes it possible to calculate the theoretical contributions of phosphorus by subwatershed and to subsequently validate them in the field. As a result, subwatersheds that generate phosphorus can be targeted more effectively.
The methodology developed by Groupe Hémisphères has the advantage of distinguishing between natural and man-made sources of phosphorus and it relies on the latest advances in lake conservation. Conclusions are not based solely on an acceptable phosphorus concentration limit, but also reflect the specificities of each subwatershed and the development and conservation constraints.
In order to fix problems associated with an excess of phosphorus and thus prevent the deterioration of our lakes, Groupe Hémisphères:
- analyzes soil use at the watershed level;
- estimates the phosphorus balance according to its origin, whether internal (sediments) or external (wastewater, surface runoff, logging, agriculture, industry, etc.);
- identifies the subwatersheds, and the activities within them, that generate phosphorus;
- recommends relevant and realistic solutions to lower the amount of phosphorus.
Lake and Stream Quality Monitoring
Monitoring the quality of lakes and streams is essential to better document the effects of protection measures. This can also prove useful in determining the contamination level of a lake, stream or adjacent ecosystem, and also makes it possible to find the source of contamination. To monitor water quality,Groupe Hémisphères:
- regularly takes water samples to analyze one or several parameters;
- monitors water contamination under different conditions (low water, rise in the water level, heavy rain, etc.);
- takes sediment or contaminated soil samples;
- analyzes the results according to the criteria defined by the provincial and federal governments.
Characterization makes it possible to evaluate the nature of streams. Based on its characteristics, the presence of a fish habitat can be validated or excluded. It also enables, if necessary, the measurement of contamination levels and identification of the contaminant’s preferred migration paths. The body of data gathered will allow for better identification of the protection or restoration measures needed. To compile the data required for such an analysis, Groupe Hémisphères:
- measures the width, depth, temperature, slope and flow velocity of streams;
- identifies the type of substrate and the vegetation present;
- uses sediment traps to determine the contaminant’s preferred migration paths;
- analyzes the sediments collected in accordance with the CCME and MDDEP guides;
- analyzes the flow of the surface water to determine the role played by erosion as a preferred migration path of contaminants;
- analyzes the water’s physico-chemical parameters (turbidity, pH, nitrogen, phosphorus, metals, hydrocarbons, etc.);
- shows the links between streams and the water table using an approach at the watershed level;
- identifies the quality of the fish habitat (for more information, refer to the Fish Habitat Characterization service under Ecosystem Characterization and Mapping).
In collaboration with the INRS-ETE research team, Groupe Hémisphères benefits from a strong scientific expertise in the detection and estimation of chlorophyll a concentration ([Chl-a]), as an index of presence of cyanobacteria in freshwater lakes in southern Quebec, using the SCHORE tool (System for CHlOrophyll Remote Estimation). Groupe Hémisphères:
- uses an operational method of quasi-real-time detection of algae bloom;
- integrates the results of satellite image data as a complementary decision-making tool in all the services offered both for the assessment of the health status of lakes or for the implementation of preventive actions to be undertaken at the scale of the watershed of our waterbodies;
- establish priority plans for field missions according to the level of deterioration and the importance of the waterbodies affected;
- compares the results obtained from the key parameters used (Chl-a, suspended matter, transparency) with other indicators of the state of health of the waterbody (periphyton, herbaria, etc.)