Semiquantitative surveys for the study of beach morphology

The global climate change and its effects on environmentally sensitive coastal areas have led both scientific and economic organizations, to implement coastal management plans. One weakness of this scheme is the lack of statistical data, especially in the so-called Third World countries, which by their economic characteristics do not allot funds for this type of study. It would be interesting to have easy low-cost survey methodologies, accessible to people with limited technical knowledge, yielding results that could be used by the specialists in coastal management. That is a kind of appropriate technology. Thus, experiments were made with a methodology based on a semiquantitative beach survey, adapted to local people conditions. They were carried out on the coast of Monte Hermoso (Buenos Aires prov., Argentina), where there is knowledge of both beach and the sea sediments, dynamics and climate from previous studies. Periodically the survey can be accompanied by expeditive topographic beach profiles. Near-shore and climatic observations with conventional methods, would be important for the understanding of the coastal processes that generate the morphological variation of the beach. The methodology is based on a semiquantitative descriptive survey, which provides a wealth of reliable information, and thus inferences about the behaviour of the beach along the time. Topographic sketches are made from target beach areas, turning the information into defined symbols that indicate the orientation of ridges, runnels and their flow, outcrops, etc. Dimensions are measured by estimating a metric grid. In order to be located during the successive campaigns the target beach areas are referenced to natural or cultural elements of easy recognition along the coast. Thus, beach change during a given period can be compared. The records are transferred to a digital graphic database to generate maps using a graphing program and a Geographic Information System. They are evaluated individually and also compared between successive campaigns, in order to establish changes on beach morphology. The results are chronologically compared to infer the trends of sediment movement and the seasonal and annual behaviour of the beach. The length of time to develop the processes of erosion and deposition can also be determined.