AN INFORMATION SYSTEM TO ANALYZE AND MONITORING COASTAL AREAS FOR PLANNING SUSTAINABLE DEVELOPMENT. APPLICATIONS FOR SANTOS ESTUARY (BRAZIL) AND BAHIA BLANCA (ARGENTINA)
ALMEIDA GUERRA, PAOLA BRUNELA
This thesis is developed within the ECOManage Project which have the strategic objectives to understand and quantify similarities and differences of estuarine system function in response to anthropogenic impacts in order to recommend restoration and/or sustainable development measures and to provide scientific support to local environmental managers on best-practice policies on 3 different coastal zones, including an estuary with mangroves (Santos-Brazil), a large estuary with wide intertidai areas (Bahia Bianca-Argentina) and a fiord (Aysen-Chile). This thesis focus mainly on two of Ecomanage study areas: Santos (Brazil) and Bahia Bianca (Argentina). Coastal areas, broadiy defined as near-coast waters and the adjacent land area, are nowadays one of the most threatened zones all over the world, due to their attractiveness, convenience and availability of resources for urban and industrial development. Therefore, many of these areas worldwide have reached critical environmental conditions as a result of great anthropologic pressure and overexploitation of their resources. Coastal areas are among the most vulnerable of Earth's ecosystems, any activity carried out in these areas should be carefully planned since what happens to the coasts has effects that reach far beyond their local aquatic and human communities, thus, causing irreparable or long term consequences. The two study areas that this thesis approach are characterized for being under significant environmental stress specially caused by poor urban planning and other anthropogenic activities like intensive agriculture. Santos is characterized by the presence of valuable and unique ecosystems as Mata Atlantica (Atlantic forest) and mangrove forests that are currently under great stress due to strong urban development in the area, which is also affecting the quality of its estuary. For this reason and so to have an appreciative idea of water quality conditions of Santos Estuary a quality index was also calculated applying Fuzzy set principles and based on water, sediment and organism samples collected by CETESB in 1999 and 2000. The quality index highlighted those areas with bad, moderate and acceptable pollution in the estuary. Bahia Bianca it is characterized by its extensive crop fields and pastures for grazing which make of i t one of the most important provinces in Argentina for grain and wool exportation. These area is under stress due to the intense agricultural activities which cause soil erosion and land degradation, however it is less environmentally affected than Santos Estuary. The general aim of this research is to create a complete information system using GIS and remote sensing techniques as data sources for the analysis of local problems of Santos and Bahia Bianca i.e. soil loss, urbanization. Furthermore, to estimate and compare rates of soil erosion obtained by two different erosion models stressing the importance of vegetation coverage as prevention of soil loss processes affecting these two study areas. The integration of landcover analysis making emphasis on multitemporal studies in the area of Santos to detect landcover change over a seven year period and the prediction of landcover change using specific software and modeling techniques was also included as an important source of information for the present and future studies. A Spatial Decision Support System (SDSS) was elaborated for Santos study area to tackle one of its most important problems, urbanization, therefore providing local authorities with a reliable tool for decision making processes. Santos landcover change analysis highlighted the most vulnerable areas regarding anthropogenic pressures, mainly deforestation and urbanization. Results obtained emphasize that areas mostly affected by anthropogenic activities are located on low and medium elevations, while those areas characterized by high elevations and steep slopes are less influenced by human activities. Most of the classes in both cases seem to remain as themselves, between 70% and 90% of the area represented by each class does not suffer any impact or transformation into other class, which is quite significant in terms of environmental impact. Landcover prediction of 2010 was obtained through interpolation of surfaces based on the input landcover maps of 1993 and 2000. Landcover trend map of 20 l O highlight an apparent decrease of anthropogenic effects and a more uniform landcover. This could be justified by the improvement in application of environmental laws in the area (CONAMA, 2002). The possibility to predict future landcover is quite significant for performing environmental assessment and preventing uncontrolled anthropogenic activities in this way foreseeing possible scenarios regarding landuse and lancover after a specified number of years. Another important factor that was taken into consideration for Iand degradation and environmental impacts of human activities in these two areas, was the calculation of erosion risk maps using two different models, the RUSLE and USPED, the latest one also gives a quantification of deposition processes taking place. Erosion rates tend to be quite low for both study areas. In Santos and Bahia Bianca it seems that erosion processes are mainly determined by topographic characteristics of each area. Lower erosion rates are found on plain terrains: in Santos mangroves have very low erosion rates, while low vegetation have higher erosion rates; for Bahia Bianca intertidal flats have very low erosion rates, while bare soil at higher elevation increase its erosion rates. Nevertheless, in Santos Mata Atlantica of highlands is mainly found at elevations of more than 570 m, but erosion rates are still very low, this fact highlight the importance of a good vegetation cover in those areas at high risk of erosion. However, erosion rates obtained for Santos and Bahia Bianca, are quite lower than expected, very high erosion values were found only on steep slopes. Unfortunately, validation of erosion-sedimentation results was not possible since in-situ field measurements were not available, nevertheless, results tend to be quite reliable if compared to previous studies performed in nearby areas with similar characteristics. Nevertheless erosion modeling is an important tool for assessment of soil loss processes and elaboration of soil erosion risk maps which are useful references for planning future activities, decreasing current erosion effects as well as preventing future soil degradation. Finally, the elaboration of a Spatial Decision Support System for analyzing urbanization problems in Santos was also possible by the application of GIS. The SDSS was designed to evaluate urban problems in Santos, as there is a considerable number of people living in protected areas as mangrove ecological reserves, which put significant pressure on this fragile and unique ecosystem, so making their relocation an important issue to be solved. In most of the cases these people belong to the lowest social class, characterized by very low incomes and living in extreme poor conditions, which make the difficult task of relocation even more difficult. These people must be conveniently moved as soon as possible to adequate and safe areas. The SDSS indicates the most appropriate places for doing so, taking into consideration a series of local factors and constraints such as, topography, water bodies, existing urban settlements, erosion and landuse, that are the basis of the analysis performed to determine "suitable" locations. The SDSS was an important asset that facilitated the proposal of feasible solutions and viable recommendations to improve urbanization problems in the area of Santos and surroundings. For this reason the elaboration of a SDSS within this thesis, was intended to be a useful and reliable tool to help local authorities with the decision making process for solving Santos most critical threats affecting the city at the present time. It is important to provide regional responsible authorities with the right tools as remote sensing and GIS and reliable planning sources like SDSS thus, helping them in the decision making process for efficiently face current problems avoiding a worsening of the present scenarios.