开封市黄河滩区土地资源规避洪水风险的安全利用

基于ArcGIS与ERDAS遥感影像制图软件,利用2007年SPOT2.5m分辨率遥感影像,结合实地调查,详细编绘了开封市段黄河河道边界、开封段黄河滩区土地资源的利用现状。采用1992~2007年最大洪峰时期的TM影像与沿河水文站点的观测资料,提取1992~2007年7个典型日期的河道行洪边缘线,与本底数据叠加,编制了开封段不同常遇洪水流量下滩区淹没范围。按照黄河下游二维水沙数学模型,采用2004年汛后河道大断面资料,计算生成不同流量级大洪水在滩区的可能淹没范围图(淹没区边界)。在此基础上,结合土地资源管理与河道行洪安全性的要求,总结当前黄河下游滩区利用开发的现状与存在问题,制订土地安全利用规避洪险的原则,规划土地安全利用分区,分为临河风险缓冲带、近河宜耕地带、相对稳定利用带(中风险带)和稳定利用带。提出了黄河滩区土地资源合理安全利用的对策。

The safe use of land resource to avoid flood risk within the lower Yellow River in Kaifeng

The Yellow River channel boundary and beach land use within Kaifeng City were mapped in detail by using 2007 SPOT 2.5 imagery, field surveys, and ArcGIS and ERDAS software. The river channel flood fringe lines of a typical 7-year period between 1992 and 2007 (less than 8000 m³/s) were generated from Landsat TM images of annual largest flood peak between 1992 and 2007, in conjunction with hydrological data along the Yellow River. Additionally, the submerged Yellow River beach areas with certain regular flood flows within Kaifeng City were created overlaid with background data. Certain levels of large floods and their potential submerged areas were calculated within the Yellow River beach in Kaifeng (especially over 8000 m³/s) based on the mathematical model of the 'downstream runoff and sediment of Yellow River' together with data obtained from a large cross section of the river channel after 2004. According to land resource management and safety requirements for flood transit within the channel, the current issues regarding the lower Yellow River are discussed, including the increased threat of floods in low beach villages, the infrastructure of agricultural development, the living condition of farmers within this Yellow River beach area, and the negative effects of brick-tile kilns and borrow pits on farmland and farming activities. Four principles of safe land use to avoid flood risk are proposed as follows: 1) protecting and using land resources to improve ecological and economic efficiencies as a whole; 2) utilizing land resources based on suitability; 3) prioritizing 'easily exploitable beach land', such as high and flat beach; 4) exploiting land resources intensively while decreasing beach land utilization rationally. Finally, four zones of safe land use to avoid flood are suggested in Kaifeng beach: a) the risk buffer zone close to the river channel (less than 4000 m³/s, about 200 m from the river course waterfront); b) the zone suitable for cultivated land near the river channel (4000-6000 m³/s); c) the zone of relatively stable land use (6000-8000 m³/s); and d) the zone of stable land use (above 8000 m³/s). At the same time, important measures of safe use beach land resources to avoid flood risk are proposed.