# A MAC Protocol to Support Monitoring of Underwater Spaces +
## 5 Application Scenario  
UWSNs may be used in different application areas for monitoring, from military to environmental scenarios. As explained before, more than 70% of the Earth is covered by the ocean, and most of it is still unexplored. One of the hot topics in ocean research is related to the interaction of the sea and the coast in the presence of human activities. In this sense, we are using this proposal in the design of an underwater sensor network to monitor several variables in the Bahia Blanca (Argentina) estuary. This city is the home of Ingeniero White port, which was originally used to export crops and fruits from a large area. In the last 30 years, this site has been surrounded by a large petrochemical nucleus, refineries and fertilizer plants, as well as deep water harbors. This means that periodical dredging, artisanal and commercial fisheries and oil and cereal cargo vessel traffic usually affect this area, as well as the direct impact of the city. Several environmental studies have been done in the estuary, mainly in the inner part of it. For this reason, there is a large time-series database on physic-chemical parameters that has been assembled. These series are very important, as they provide information on the entry points of the main rivers and the main human activities through the city sewage. The estuary has a large mudflat with a rich ecosystem supporting a large population of wildlife, including migratory birds, crabs, fishes and molluss. The increment of the port activity and the incorporation of new industrial activities have modified the ecosystem of the estuary. At present, the influence of the port, the industrial activities and the city itself is being analyzed in the outer part of the estuary, especially in the surf zone outside the estuary. Several seaside towns at 50, 80 and 170 km away from the port are under analysis. For the first of these towns, Pehuen Co, it has been already proven that the ecosystem is under a severe effect of the port. The estuary has very strong tidal currents, and these affect the neighbor beaches with a large tidal amplitude. The other two, Monte Hermoso and Reta, are located further away, but most importantly, they are at open sea. Figure 14 shows a capture of the satellite image of part of the estuary with the city of Bahia Blanca and its port on the left and the seaside towns along the beach. The black circles represent the probable locations for the sensor networks. The project tries to prove whether the port has modified the ecosystem of these beaches. For this, an underwater sensor network will be deployed in the area to measure different parameters, like water turbidity, spectral radiance, temperature, density, salinity, monitoring volatile organic and inorganic compounds. These parameters should be measured at different depths and distances from the coast and along several months to capture seasonal variations. Although it is possible to deploy a wired  
Figure 14: Satellite picture of the Bahia Blanca estuary. network, in the surf zone and under the effects of waves, it presents severe drawbacks. Besides, as these beaches have people living in the seaside towns, the sensors and cables may be broken. Different clusters of nodes should be deployed along the coast to determine the presence of pollutants and variations in association with the tidal currents and the effect of wind. The first cluster should be deployed in the proximity of the port; a second group of sensors would be deployed in the mouth of the estuary, while the third one in Pehuen Co. Between Monte Hermoso and Pehuen Co, there are just 25 km with no river mouths in the middle. The fourth cluster will be anchored in Monte Hermoso. Two important river mouths are on the coast between Monte Hermoso and Reta, Sauce Grande and Quequen Salada. Intermediate clusters are deployed at these points to measure the influence of the rivers in the seaside. Finally, in Reta, there is also a small water stream mouth, the river El Gaucho.