Map Viewing Service (WMS) of the dataset: N_ZONE_ALEA_PPRN_20140345_S_032

The mapping of the hay removal of clays in the commune of Castelnau-d’Arbieu in the Gers department is extracted from the departmental mapping derived from the BRGM. This mapping is a zoning of the probability of occurrence of the phenomenon of shrink-inflating of clay soils. A susceptibility map was first drawn up on the basis of purely physical criteria by the BRGM from the geological maps of the department, which were interpreted taking into account the following factors for each geological formation: — the proportion of clay material within the formation (lithic analysis); — the proportion of blowing minerals in the clay phase (mineralogical composition); — the geotechnical behavior of the material. For each of the clay formations identified, the hazard level is ultimately the result of the level of susceptibility thus obtained with the density of sinister swelling, reported to 100 km² of actual urbanised outcropping surface.本数据集提取自法国地质矿产调查局（Bureau de Recherches Géologiques et Minières，BRGM）生成的热尔省区域测绘成果，内容为热尔省卡斯泰尔诺-达尔比厄（Castelnau-d’Arbieu）公社范围内的黏土胀缩现象分布测绘图。该测绘成果为黏土土壤胀缩现象发生概率的分区图。法国地质矿产调查局首先以该省地质图为基础，基于纯物理标准编制了易发性分区图，编制过程中针对每个地质地层，综合考量了以下因素： — 地层内黏土物质占比（岩性分析）； — 黏土相中的风成矿物占比（矿物组成）； — 材料的岩土工程特性。针对已识别的所有黏土地层，最终的灾害等级由前述得到的易发性等级，结合每100平方千米实际城市化出露地表的灾害性膨胀事件密度共同确定。