Coastal Evolution and Human Interventions: an Integrated GI for Littoral Management in Molise

Stefano Cardinali, Edi Valpreda

Department of Environment, Climate and Sustainable Development
ENEA - National Agency for New Technologies, Energy and the Environment (IT)

As in the whole Italian country, the Molise littoral is greatly retreating in latest 50 years. More than 86 hectares have been lost in about 30 kilometres of sandy beaches.
Having in this littoral the coexistence of natural high environments relevance (SIC: Communitarian Relevance Sites) with important human interventions due to Termoli commercial harbour, and with a strongly and continuous coastal defences construction to prevent coastal settlements from erosion.

The study compares, inside a common GI environment, costal lines evolution from 1954 till nowadays (2006), littoral natural "goods" (coastal dunes, pinewoods, coastal wetlands and sandy beaches) and human settlements and interventions done in the seafront for coastal risk mitigation and for industrial endeavour (harbours, marinas, etc).

A certified collection of multitemporal data has been achieved using different sources: ortho and traditional Technical maps, aerial photos, satellite imageries, DGPS surveys also done during the study. Having different accuracies and different updating, all data have been handled to dispose of data set with numerical format and common cartographic reference system (WGS84 UTM). Moreover a proceeding to evaluate, in quantitative way, the positional accuracy after data managing, has been assumed to can consider these "values" inside spatial analyses with which the coastal erosion hazard has been calculated.

The changes of coastline position comes combining twosome subsequent cartographies (using DSAS GIS extension (from USGS) and transect spaced out 50 metres coastline long) ; the coastal erosion hazard derives from further comparisons between these "changes" and beach amplitudes. The study highlights the increase and displacement along the coast of the maximum values of erosion hazard expressed as the estimation of time in which the coastal trend will induce the whole loss of the present sandy beaches width.

In the same GI scheme, the coastal defences, harbours and armoured mouths have been drawn (as polygons) and classified by a complex attributes set.
Theirs outlines derive from past and present cartographic sources, and their attributes come from interviews with local policy makers, citizens, etc. In fact no archives were available for these manufacts, only an unwritten memory be there.
The result is a complex database, developed with ARCGIS 9.0, having metadata information applying the ISO-19115 reference model.

The research highlights that, after a general sediment supplies decreasing (after 1960) due to dams building, there is in the last decades a clear relation between main coastal damages and human coastal hard interventions. These results could be a very important tool for a responsive coastal planning but highlights also the difficulties to uses that GI knowledge in local planning when the decisions are made without a concrete technical contribute and when GI wholly underlines the force-driving relationships.

The research was partly done inside the INTERREG NOE' OCR - PROJECT - LITTORISK Subproject