Simple download service (Atom) of the dataset: Limit of the reference flooding zone by hydraulic and hydrogeomorphological approach from Sarsonne to Ussel in Corrèze

L_ZI_SARSONNE_2001_LIM_L_019

The study determined the flooding areas of the Sarsonne at Ussel by hydrogeomorphological approach on the upstream and downstream areas of the urbanised part (maximum right-of-way only). The hydrogeomorphological approach is a naturalistic approach based on reading the morphology of the alluvial plain. It is supplemented here by extrapolation of the water line from a flood known to establish the reference flood water line.
This reading of the morphology of the alluvial plain has been clarified on the urbanised area, thanks in particular to topographical works, allowing the definition of heights and flow rates in the crossing of the urbanised area. The flooding zone was determined by calculating the water line of a centennial flood (reference) determined by extrapolation of the 1994 flood water line, extrapolation based on topographical knowledge, the difference in flows between the 1994 event and a centennial event. Topographic knowledge has been used to determine water heights (between 0 and 1 m and > 1 m); flow velocities were defined qualitatively from valley morphology primarily. The crossing of these two parameters allowed to map the hazard (strength = H > 2 m or 1 m < H < 2 m and V > 0.5 m/s or 0 m < H < 1 m and V > 1 m/s; mean = 1 m < H < 2 m and V < 0.5 m/s or 0 m < H < 1 m and 0.5 m/s < V < 1 m/s; low hazard 0 m < H < 1 m and V < 0.5 m/s).

L_ZI_SARSONNE_2001_LIM_L_019

本研究采用水文地貌学方法（hydrogeomorphological approach），针对于塞勒（Ussel）境内萨尔松讷河（Sarsonne）城市化河段的上下游区域（仅以法定最大河道管理岸线范围为准），划定其洪水淹没范围。水文地貌学方法是一种基于冲积平原（alluvial plain）形态解读的自然主义研究路径，本研究通过已知历史洪水的水位线外推，构建基准洪水水位线，以此补充该方法的应用。

得益于地形测绘工作的支撑，本次冲积平原形态解读在城市化区域内得到了细化完善，得以明确城市化河段的高程与流量参数。本次洪水淹没范围通过百年一遇基准洪水的水位线计算划定，该水位线基于1994年洪水水位线外推得到，外推过程结合了地形测绘认知以及1994年洪水与百年一遇洪水的流量差值。

研究借助地形测绘数据确定了水深参数（分为0~1米、>1米两个区间）；流速参数则主要依据河谷形态定性确定。结合水深与流速两个参数，可绘制洪水风险分布图并进行分级：高风险（强度等级为：水深H>2米，或1米<H<2米且流速V>0.5米/秒，或0米<H<1米且流速V>1米/秒）；中等风险（水深1米<H<2米且流速V<0.5米/秒，或0米<H<1米且0.5米/秒<V<1米/秒）；低风险（水深0米<H<1米且流速V<0.5米/秒）。