Integrated Use of MERIS and other EO Data for Water Quality and Red Tide Monitoring along United Arab Emirates Coasts
Ceriola, Giulio; Manunta, Paolo
Planetek Group, ITALY

Coastal zones mark the transition from land to ocean. A large percentage of global population resides within, or with easy access to, these areas. Moreover most of the economical and productive activities are located from the coastal area (100km from the coast). They include transport, shipping, oil and gas, mineral extraction, fisheries and tourism to name a few sectors. A large amount of these sectors depend on the coastal ecosystem being healthy or Living Ocean, so they need to be constantly monitored. Monitoring of coastal water ranges from the direct measurement of bio-physical parameters (e.g. chlorophyll, sea surface temperature, turbidity, salinity, oxygen) to the use of (forecasting) model to detect and make a prevision about the variation of some key parameters.

Currently the most accurate method to monitor Water Quality (WQ) is by means of on-site measurements. However this method has some drawbacks mainly linked to the capability of sparse sampling - in respect to space and time - to be representative of wide areas and of large periods of time.
Together with this traditional means the use of EO techniques has been recently increased: optical and thermal sensors are able to measure some parameters linked to the optical properties of the water surface, together with the surface temperature. A number of space-related projects have dealt with the realization of EO based WQ monitoring systems
The Coastal Outfall project, funded by ESA under the Value Added Element (VAE) of the EO Envelope Programme, is focused at implementing a suite of products and EO data services specifically targeting two growing sectors: Waste Water Treatment plants and Desalination plants. Concerning the latter, the coast of the United Arab Emirates hosts some of the largest desalination plants in the world and their operation is linked in two ways to the status of the water quality near the coast: from one side the water they release could have an impact on the coastal ecosystem and from the other side they can be strongly affected by harmful and not-harmful algae bloom. In particular the local phenomenon known as Red Tide in the last 4 years had a relevant impact for desalination plants causing severe damages and stopping the operations.

Some actors are involved into the WQ management in the Arabian gulf, among them the Environment Agency of Abu Dhabi (EAD) is a governmental agency committed to protect and manage biodiversity, to provide a clean environment and to promote Sustainable Development in the Emirate of Abu Dhabi. The interest of EAD into the project concerns in particular desalination plant operation, for the monitoring of WQ near the plants. Of particular interest is the detection of Red Tide and other (harmful) algae blooms which have a relevant a socio-economical impact, involving not only desalination plants, but also e.g. aquaculture industries or public health.

The Coastal Outfall project, building on existing prototype EO products, has the objective of implementing and demonstrating a monitoring service able to derive NRT WQ parameter and Sea Surface Temperature from medium resolution sensors like MERIS FR and MODIS AQUA. This monitoring in particular is aimed at identifying Red Tide events by detecting anomalous values in some WQ parameters, with the support of higher resolution images (e.g. MODIS first bands, Landsat5, SPOT, etc.) to empirically retrieve Chl and TSM for lowering false alarms. Moreover when a Red Tide alarm is confirmed the use of a very high resolution sensor like DubaiSat-1 is considered to be used for a precise determination of the Red Tide perimeter, giving a concrete support in preventing and forecasting the possible Red Tide effects.

The present work describes the analysis performed within the Coastal Outfall project and the designed service demonstration scenario over the UAE area and the preliminary results obtained.