|Paper title||Development of Water Quality Indicators for Transitional Waters using Sentinel Data|
|Form of presentation||Poster|
Water quality is a key worldwide issue relevant to human consumption, food production, industry, nature and recreation. In fact, monitoring and maintaining good water quality are pivotal to fulfilling the UN Sustainable Development Goals and enshrined in European policy through the Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD). Inland, transitional and coastal waters are increasingly threatened by anthropogenic pressures including climate change, land use change, pollution and eutrophication, some of which remote sensing can provide useful and continuous monitoring data and diagnostic tools for.
The European Copernicus programme includes satellite sensors designed to observe water quality and serves data and information to end-users in industry, policy, monitoring agencies and science. Three Copernicus services, namely Copernicus Marine, Copernicus Climate Change and Copernicus Land, provide satellite-based water quality information on phytoplankton, coloured dissolved organic matter, and other bio-optical properties in oceanic, shelf and lake waters. Though the transitional waters are partly covered by CMEMS coastal service, the approaches are distinct in the different services.
Responding to global needs, the H2020 Copernicus Evolution: Research for harmonised and Transitional water Observation (CERTO) project (https://www.certo-project.org/) is undertaking research and development to produce harmonised and consistent water quality data suitable for integration into each of these Copernicus services, and, thus, extend support to the large communities operating in transitional waters such as lagoons, estuaries and large rivers. This integration is facilitated by the development of the CERTO prototype, a Software-as-a-Service (SaaS) that contains modules on improved optical water classification, improved land-sea interface and atmospheric correction algorithms, and a set of selected indicators. The development of suitable indicators that respond to user needs is of utmost importance to demonstrate the added value of the CERTO upstream service to potential users and stakeholders in the downstream service domain. By providing a harmonised capability across the Copernicus services, the CERTO prototype will enable the evaluation of these indicators for the continuum from lakes to deltas and coastal waters and support intermediate and end-users in industry and policy sectors, while ensuring compliance with their own monitoring requirements.
To demonstrate the value of CERTO outputs, six case study areas are selected: i) Danube Delta; ii) Venice Lagoon and North Adriatic Sea; iii) Tagus Estuary; iv) Plymouth Sound; v) Elbe Estuary and German Bight; and vi) Curonian Lagoon. Eighteen local and national stakeholders in the six European countries where the CERTO case study areas are located have been interviewed to identify user needs in terms of the contents and relevance of the CERTO prototype.
Initial analysis of the user requirements collected points to a need for: i) improved products with respect to spatial and temporal resolution, ii) water quality indicators that aggregate data and iii) help in decision making and reporting, such as for the EU WFD and MSFD. To address these needs, several indicators are being developed within CERTO that use satellite-based estimations of water turbidity, suspended particulate matter and chlorophyll-a concentration, and include region-specific mean values, anomalies, percentiles (e.g., chlorophyll-a 90th percentile) and trends. Two indicators are based on turbidity and suspended matter and aim at aiding the planning and management of industry and local authorities: one will allow the analysis of the maximum turbidity zone (or high loads zone), the second one will aim at characterising the dredging events and impacts in the study areas. Another indicator based on the phenological analysis of phytoplankton blooms (i.e., bloom timing) that occur in these transitional regions is also under development. The aim of this indicator is to further understand ecosystem functioning and to provide support for the implementation of additional phytoplankton metrics for the EU WFD. Based on Sentinel-2 and Sentinel-3 data, these indicators are transferable and comparable across time and space and provided in near-real-time to provide faster response. In addition, a more complex indicator is under development, i.e., the Social-Ecological System Vulnerability Index (SESVI), which integrates local knowledge and data, 3rd party modelled and satellite data as well as CERTO outputs, to characterise the main pressures in the case study areas and highlight hotspots of vulnerability in lagoons and estuaries due to human pressure and climate change.
This paper presents the suite of CERTO indicators that aim to better support water resources management and decision-making, and shows the progress achieved thus far.