基于GIS栅格数据的叶尔羌河灌区洪水风险动态模拟与识别

【目的】加强叶尔羌河灌区防洪规划与管理。【方法】根据1959-2015年叶尔羌河灌区洪水事件,以叶尔羌河喀群渠首至艾力克塔木之间的区域为研究对象,应用GIS工具生成数字高程(DEM)栅格数据,构建了FloodArea洪水淹没模型,计算了高情景和低情景2种典型历史洪水量级下的淹没范围、水深、流速等风险要素,绘制了研究区的洪水风险图。【结果】叶尔羌河洪水淹没风险区主要限于灌区河段附近,重现期为20a洪水风险较高,卡群水文站以下河段多处被洪水冲毁部分河段河堤,洪水漫溢淹没区主要分布在沿河道两侧灌区的地势低洼区,洪水淹没范围较大;重现期为5 a洪水的流程强度和洪水淹没区比重现期为20 a洪水有所减少,危险性等级降低,灌区以及居民点基本未受到影响。【结论】通过反演高情景和低情景2种典型洪水,生成的洪水风险灾害指示图能够科学地模拟、预测洪水淹没范围,防洪工程的重点是在平原灌区莎车县、麦盖提县、巴楚县河段。

Using GIS Grid Dataset to Simulate and Identify Flooding Risks in Irrigation Areas in Yarkant in Xinjiang

【Objective】In order to strengthen the flood control planning and management of Yarkant River irrigation area,the paper carried out the flood inundation risk simulation study.【Method】The analysis was based on flood events measured in 1959—2015 from the region between the Kaqun canal head and Eryketam.The merging GRID raster file was generated from DEM,and a flooding inundation routing model-Flood-Area-was developed to calculate flooding risk factors such as inundation area,flood depth and flow rate,under different scenarios.【Result】The flood inundation area was limited to the vicinity of the flooding plain.The 20-year return of flooding risk was high,which could cause overflow and inundation losses in parts of the downstream reaches of the Kaqun gauge with the inundation area distributed mainly in the lowland of the irrigation areas along the river.The frequency of 5-year return of flooding risk and its associated inundation area were both less than those of the 20-year return.The 5-year return of flooding risk of the Yarkant River was low and it dose not result in loss in irrigation areas and residential areas.【Conclusion】The Flood-Area model was able identify flooding risks and calculate inundation areas duo to high and moderate flooding.Flooding-control projects should focus on sections of the river in the plain areas comprising of Shache County,Makit county and Bachu County.