Dataset Direct Download Service (WFS): N_ZONE_ALEA_PPRN_20140199_S_032

The mapping of the hay removal of clays in the commune of Castelnavet in the department of Gers is extracted from the departmental mapping 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.本数据集的图件源自法国地质矿业研究局（BRGM）编制的热尔省区域地质图，为卡斯泰尔纳韦镇内黏土干燥收缩现象的相关制图成果。该图件为黏土土壤胀缩现象发生概率的分区图。法国地质矿业研究局（BRGM）首先基于纯物理准则，利用该省的地质图件编制了胀缩敏感性图（susceptibility map），编制过程中针对各地质单元，综合考量以下因素开展解译：—— 地质单元内黏土物质占比（岩相分析）；—— 黏土相中膨胀性矿物占比（矿物组成分析）；—— 该物质的岩土工程特性。针对已识别的各黏土地质单元，最终的灾害等级由前述得到的敏感性等级结合灾害性胀缩密度确定，该密度以每100平方公里实际出露的城市化地表面积为统计基准。