Small, Medium and Large Scale Maps in Coastal Studies. What Happened to Arno's Mouth between the XIV th

Summary: An ever growing number of experts and specialists in modern territorial evolution use historical cartography as a primary source. We can say the same for those interested in the evolution of a coastline, not necessarily from an historical point of view, but because they are engaged in counteracting what appears to be an un-restrainable phenomenon of erosion that in 2006 concerned 42% of the low sandy beaches of the Italian coast. We do not have to go too far back in time to see that the intermittent phenomena of an advancing and retreating coastline is not new. Compared to a century or two ago, however, erosion today not only causes severe and immediate economic repercussions, but in the short and intermediate time frame risks the same repercussions on population distribution and settlement at both a national and regional level. Naturally this is all due to global factors: climate change, rising sea levels, greenhouse effect, and others. Few negationists are left, but the panorama of hypotheses on the causes of climate change, especially when we limit the area of investigation, will continue to grow. This is also because not all low Mediterranean coastlines react in the same manner to the same solicitations. In the case of Tuscany, different reactions may be visible in areas distant only a few kilometers from one another, and sometimes only a few hundred meters. Geo-environmental factors such as subsidence, tectonics, sea currents; anthropic factors such as deforestation, land fill, river bed quarrying and canalization, harbor construction, and the remedies adopted to stem the effects of the above: all contribute to differentiate the coastline's response. Beginning with the latest medieval period, anthropic factors can be studied with some possibility of success and correct interpretation, even though they are sometimes unpublished and only available in historical archives. Here we can discover the exact (or almost) date when a harbor or breakwater was built, a meander cut, a river mouth moved. And from a climatic viewpoint, limiting ourselves to rainfall, even though reliable figures lack for the more distant centuries, we have a fairly complete record of the more important floods that indicate periods of incessant rainfall. It is therefore important to thoroughly study the evolution of a specific section of coastline. Over the last five centuries, historical cartography has become an exceptionally useful instrument in research using integrated sources – descriptive, historical hydrographic essays, chronicles, and so forth. In the following pages, synthesized as deemed necessary as an extract of a more lengthy study in print 1 , we will examine the accretion and erosive phases of the mouth of the Arno River, the fourth longest Italian river and the longest in Tuscany, from the XIV th century to the last quarter of the XIX th century. These pages will also offer an initial overview of the data regarding the sedimentary surplus that influenced an area of six kilometers to the left and right side of the river mouth: San Rossore, a natural park almost without settlements, to the north, and Tombolo with the tourist towns of Marina di Pisa and Tirrenia, heavily urbanized during the last century, to the south.