Geoscience Reference
In-Depth Information
spatial change, in others, it will be necessary to mobilize the indicators built from
spatial statistics. For example, “the distance to the nearest neighbor or to the
k
th
nearest neighbor”, typically used in probabilistic approaches of spatial
configurations [RIP 05], may be used to describe the degree of concentration in a set
of points at multiple dates. All these measures thus constitute a summary of the
“history” of the whole spatial organization. Let us take the example of a set of
archaeological settlements stamped following a time granularity at the century level
in a region in the South of France (the Lunellois and the Vaunage [FAV 98]). These
settlements are described by a certain number of indicators characterizing the level
and the activity of the settlement as well as the function of the settlement. The
analysis of the coevolution of the number of occupied sites and of their areas
provides the first image of the evolution of the settlements' structuring and allows
the different occupation phases of the territory to be identified. A deployment of the
settlement system can be observed at the beginning of the period with a very strong
increase in the number of settlements with small areas. This was followed by a
retraction, the settlements being concentrated on a smaller number of larger
settlements with a more significant area [NUN 06] (Figure 3.5(a)). Local indicators
allow a full account to be given in parallel to these evolutions from a spatial point of
view. Figure 3.5(b) shows the evolutions of the averages of the “distance to the
nearest settlement” and of the “number of neighboring settlements within less than
3 km”. These indicators, measured for each settlement occupied during the period
being considered, are two complementary ways to give insights about the local
situations. They allow the spatial inscription of the phenomenon to be highlighted.
The change of the average distance between settlements from 500 m to more than 1
km between the 1st and 5th Century illustrates the emergence of a new spatial
organization of the settlement system, with a more regular coverage of all the
territory.
Figure 3.5.
Statistical description of the evolution of a point pattern (source [FAV 98])
