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Abstract:

The downstream area of the Yellow River is a suspended river and has constantly threatened the security of Kaifeng city. The Yellow River is one of the main forces driving the geomorphological characteristics evolution of Kaifeng city. Recent developments in unmanned aerial vehicle remote sensing system -UAVRSS technology mean that research can now include both macroscopic and microscopic remotely sensed data. This paper utilized a digital elevation model (DEM) obtained using UAVRSS technology and evaluated the DEM and digital orthophoto map (DOM) of a given transect to analyze the geomorphological characteristics from the macroscopic and microscopic perspectives. Results of this research show that: the surface elevation near the Iron Pagoda is 88.44 m, the spire elevation is 143.618 m and the height is 55.183 m. The downstream area of the Yellow River in the Kaifeng city area is a typical suspended river. The surface elevation rises from 88.44m in Kaifeng city to 105 m near the Yellow River levee, while the elevation of the Yellow River is 92.25 m. The Yellow River is about 4 m above Kaifeng city and the river embankment is 16.56 m above the city. On a macro level, the transect elevation gradually decreases from north to south, which exhibits a stepwise pattern called the Four Typical Ladders. On a micro level, the most geomorphological changes were seen in the North Wall, the city-protection dike and the embankment. Those drastic changes were mainly influenced by the Yellow River floods, three major defense projects, and other human activities. The Yellow River remains the major of safety hazard to Kaifeng's steady and healthy development. Communities in Kaifeng city need to take a more active role in safeguarding their security and continuously aiding in flood control by recognizing the importance of major local defense projects.