Using an AUV for Assessing Wastewater Discharges Impact: An Approach Based on Geostatistics

Several monitoring approaches have been used to understand the physical, chemical, and biological processes associated with coastal sewage discharges. However, these efforts have not improved the understanding of the interaction of effluent plume/coastal ocean processes. Autonomous underwater vehicles (AUVs) have already been shown to be very useful for performing high-resolution surveys of small features such as outfall plumes. Some of the advantages of these platforms include easier field logistics, low cost per deployment, good spatial coverage, sampling over repeated sections, and the ability to perform feature-based or adaptive sampling. Once the data have been collected in the field, it is necessary to extrapolate from monitoring samples to unsampled locations. Geostatistics has been successfully used to obtain information; for example, regarding the spatial distribution of soil properties. Besides giving estimated values at unsampled locations, it provides a measure of the accuracy of the estimate, which is a significant advantage over traditional methods used to assess pollution. In this work, geostatistics is used to model and map the spatial distribution of temperature measurements gathered by an AUV in a sea outfall monitoring campaign, with the aim of distinguishing the effluent plume from the receiving waters and characterizing its spatial variability in the vicinity of the discharge. The results demonstrate that this methodology can provide good estimates of the dispersion of effluent, and it is therefore very valuable in assessing the environmental impact and managing sea outfalls.

Coastal pollution and mitigation measures in Turkey

Turkey is a developing country where industrial and urban developments mostly occur in coastal areas. Besides the present pollution loads, newly developed tourist areas and industries, through increased input of wastes, further stress the coasts of Turkey. In this study, the state of sewerage systems, treatment plants and sea outfalls in Turkish coasts were investigated. The pollution problems should be considered differently from region to region. Development of coastal areas appeared to be partially tourist and partially industrial in nature. Because of this fact, problems from different coastal areas were discussed in different projects and solutions were recommended.

European attitude to the disposal of wastewater in the sea: the case for a (European) network for sea outfall research

A network of European organisations with interests in the utilisation of long sea outfalls as an integral element in the sewerage of coastal communities has recently been established. The central aim is to provide a focus both for the adoption of best practices and the identification of outstanding problem areas across the European community, against the background of the standards of practice demanded by the recent implementation of the European Commission's (EC) Urban Waste Water Treatment Directive. This article is intended both to inform a wider audience of the existence of the network and to extend the call for membership both to European parties and others interested in being informed on European developments in this area.

Pollutant dispersion in the nearshore region: modelling and measurements

Some results on pollutant dispersion modelling and tracer measurements for the Mediterranean Spanish coast are presented. Two hydrodynamic models have been used to simulate wind and wave induced circulation in the nearshore and surf zones respectively. A “near field” model has been used in order to simulate the initial conditions for the local “far field” dispersion model. Two study cases are presented: The first one shows the mixing of conservative tracers in a Mediterranean surf zone from an experimental and numerical models used to predict bacterial dispersion from the main sea outfalls of Barcelona City. The comparison between dye dispersion experiments and model in the surf zone is good, while the outfall predictions show the importance of accurately modelling the effects of buoyancy on the plume.

Sea outfalls for the disposal and treatment of wastewater effluents

The paper brings together a useful summary of all aspects of design and implementation of outfall schemes for the disposal of wastewater effluents. It outlines methods of assessment of the receiving water in relation to short-term and long-term impacts using the concept of Environmental Quality Objectives, with reference to European Union (EU) Standards and United Kingdom (UK) Practice. The need for good field data is outlined with appropriate methods and an indication of cost. A discussion of predictive modelling techniques and of the need to integrate combined storm discharges is included. The principles of hydraulic and structural design are outlined with special reference to the design of diffusers and to the impact on this of different characteristics of the receiving water. Finally, a brief review is given of the construction methods available at the present time.