The impacts of Segura River (Spain) channelization on the coastal seabed.

Human actions over rivers and coasts have generated great changes along seaboard. In order to know future development of those changes, it is necessary to understand the development of the coast during the past. When there is a complex morphologic system as a result of the combination of natural elements with human construction elements, the study of the abovementioned changes requires a wider perspective than the one provided by traditional two-dimensional methods. Thus, the Geographic Information Systems (GIS) become a suitable tool for that kind of studies. In this work, GIS are used to understand changes in bathymetry, sediments properties and transport, as well as surface variations of plant species occurred in the Segura River mouth (Spain) within a period of 17 years due to the channelization of the river low course. The methodology followed here implies the integration of data coming from different sources and with different formats in a GIS, what allows for a spatial analysis. Results obtained show the grain-size spatial distribution for every period of time studied, as well as bathymetry changes and seabed morphology. It can be concluded that the construction works carried out in the riverbed have affected sediment grain-size in the area. Clays have nearly disappeared and consequently there is a descent of seabed level that affects plant species, such as Posidonia oceanica.