User preparation for novel aquatic applications based on synergistic use of CHIME and LSTM data

Kurzfassung

Two thirds of the planet are covered by water, the single most important element to sustain life. It is a habitat, provider of food, energy and recreation, but also the source of disasters. The changing climate and pollution diminish the availability of usable water, and thus increase the potential of user conflicts and public health problems. Preserving and promoting good water quality not only benefits the environment but also safeguards public health and ensures the preservation of water resources for future generations. There is a need for information on the potential of natural climate protection measures, but also regarding the preparedness to occurring threats such as toxic algae blooms or human contamination posing significant risks to water quality, water life and their habitats. Remote sensing by satellites can bring globally applicable, transboundary and large-scale monitoring solutions for current and long-term trend analysis. By combing the satellite data with modelling approaches even future projections can be calculated and applied for ecosystem assessments. The six new Sentinel Expansion missions are being developed to tackle prospective societal challenges such as global warming and its impact on nature and humans, urbanisation and food security. The combined data exploitation of these missions allows for the development of new applications bringing benefit to their end-users and thereby addressing EU policies and gaps in Copernicus user needs. In this context, the objective of the presented ESA funded AQUASUP project is to develop and validate novel concepts for the integrated use of data from the CHIME and LSTM missions, to overcome prevailing information deficiencies in inland water and coastal monitoring and management, focusing on enhanced water quality and ecosystem assessment. Combining hyperspectral and thermal imagery for advanced applications presents a promising pathway for addressing a multitude of societal challenges in the future holding the potential for understanding various impacts, such as the response of both inland and coastal ecosystems to population growth and climate change enabling to establish mitigation action plans. The project presents a first step in preparing the uptake of the new Copernicus Expansion missions together with selected stakeholders The novel applications will be based on simulated Chime and LSTM data and focus on the mapping and monitoring of aquatic environments, both inland and coastal. Four applications will be developed: A) Algae Classification and Quantification: The hyperspectral optical signature of algal blooms enables to quantify phytoplankton pigments (extent, types and concentrations), including those common to potentially toxic species, while the tolerance of phytoplankton to thermal changes is captured by combing CHIME and LSTM observations. Accurate calculations of chlorophyll-a, turbidity and water visibility (transparency) are used to create advanced products related to the quantification of cyanobacteria and the differentiation of phytoplankton functional types and pigments. B) Benthic Classification: The limiting constraint of water depth regarding the classification of benthic habitats, caused by the narrowing of usable spectral range with increasing depth, is estimated to be reduced using hyperspectral data. Improved retrieval algorithms are developed considering the noise of CHIME. The novel approach will improve the classification of benthic types and monitor the extent and spread of macrophytes and mussels in shallow water. A major goal is to distinguish quagga mussels from macrophytes in Lake Constance to monitor the spread of these invasive mussels. C) Water Temperature Models for ecosystem assessment in rivers: Water temperature is a critical parameter that influences the structure, function, and stability of river ecosystems and is a main factor influencing other water quality parameters such as oxygen and ecological adverse events such as harmful algal blooms as seen in the Oder River in Summer 2022. Based on the simulated LSTM land and water temperature data sets, a data-driven approach employing spatiotemporal, process-guided deep-learning techniques to estimate river temperatures distributed spatially along the Elbe River stream-network will be developed. The improved water temperature information will be combined with hyperspectral data to assess deterioration of water quality conditions through algae bloom detections and the discrimination into functional groups. An alert system will be established indicating critical ecological water states. D) Synthesis Products for early warning and risk indications in sea grass meadows: Enhancing the identification of biological species, including macrophytes, phytoplankton, and cyanobacteria, can be achieved by considering hydro-meteorological factors and physical boundary conditions like water temperature. The high frequent and higher resolution measurement on water temperature using the LSTM sensor as potential stressor and input to biomass model and the hyperspectral satellite sensor CHIME to map benthic habitats have the potential to provide useful insights of the growth cycle and trends on seagrass meadows. The application serves to initialise and answer scientific questions on the growth and biomass uptake (including C sequestration) of seagrass meadows in the German Baltic and their stressors. The development of the new approaches will be based on simulated data from sensors with similar specifications like EnMAP and PRISMA for hyperspectral data and TIR from Landsat or airborne sensors for the thermal data. The developed products will be tested and evaluated for different applications in selected representative use cases in Germany and Italy, covering lakes, rivers and coastal water bodies across different ecoregions. The selected users represent various stakeholder groups and are influential players within their respective fields. Their participation in testing and evaluation activities will ensure that the new approaches are tailored to address the stakeholders' real-world challenges, enabling the demonstration of viability and benefits concerning the Copernicus expansion missions. The participating users are: i) Baden-Württemberg State Institute for the Environment, Survey and Nature Conservation, ii) the State office of Environment of the region of Schleswig-Holstein, iii) the Regional Agency for the Protection of the Environment of Lombardy, iv) Helmholtz Centre for Environmental Research, and v) XYLEM. The described applications aim to prepare users to fulfil current and future regulations and policies imposed by global, EU, and regional initiatives, including the United Nations' Sustainable Development Goal (SDG) 6 on a global scale, the Water Framework Directive (WFD) - the most critical EU directive for water body protection and management - alongside the Nitrates Directive (ND) and the Drinking Water Directive (DWD) on a European level, and NATURA 2000, the Habitat Directive and Environmental Impact Assessments on a local scale.