## 3 Results and Discussions
### The Role of Geological Methods in Urban Flood Control
The Role of the Geological Method-Integrating Water Ecological Engineering Construction with Eco-Geological in the Prevention and Control of Urban Flood Disasters  
It has been recognized that urban water ecological engineering construction can greatly improve the city's ability to prevent flood disasters. By controlling soil erosion, the amount of sediment entering the reservoir or river can be substantially reduced, thereby maintaining the capacity of these water bodies to intercept floods. The water and soil loss in the upper reaches or source of the Jialu River Basin is quite significant. By the end of 2015, the total water and soil loss area was 881 km\({}^{2}\), and the average annual total soil loss was 2.16 million tons [28]. On the one hand, the loss of water and soil at the upstream or the source will lead to sedimentation and weaken the flood interception capacity of the reservoir, and on the other, sedimentation at the middle and lower reaches will lead to the blockage of the river channel and will greatly reduce its flood discharge capacity. It is estimated that the upstream siltation of the reservoir due to soil erosion has reduced the flood interception capacity of the reservoir from 260.91 million m\({}^{3}\) to 195.68 million m\({}^{3}\), which is about 25.00%. Figure 9: Land use types in study area. Developing green patches by giving due consideration to ecological geology can address this issue quite successfully. Thus, areas suitable for planting trees or grass need to be selected based on the local geological conditions. By following scientific practices in ecological restoration and management, the sediment deposition in reservoirs and river channels can be greatly reduced to maintain the capacity of the reservoir to intercept floods and the river, and to discharge flood water. At present, the amount of annual soil erosion is 3.281 million m\({}^{3}\). After ecological management, the reservoir can reduce the sediment deposition volume by 3.281 million m\({}^{3}\) every year [28], and this number is temporarily used as the standard for the improvement of the flood-holding capacity in this paper. The goal of increasing infiltration storage and river discharge capacity are achieved through the proper implementation of urban ecological engineering. Zhengzhou plans to build 54 water ecological projects within the city. These projects are planned for various areas, including the Jialu River, Lianhu Lake, Dongfeng Canal, Ruyi River, Xiushui River, Xilinuke, Yuema Lake, and Yanming Lake. After the completion of these projects, the water-covered area of Zhengzhou city will increase from 156.9 km\({}^{2}\) to 211.66 km\({}^{2}\). The urban water surface area will increase from 0.93% to 3.9% by 2020 [33]. Concept-wise, the construction of water ecological engineering is to follow \"Tao follows nature\" and not artificially destroy the law of water cycle. Geologically speaking, it is necessary to follow the laws of ecological hydrogeology. Thus, there should be no seepage prevention at the bottom of lakes and rivers, so that water can naturally seep into the ground. The area of the study area is 2750 km\({}^{2}\), and the water surface area is 3.9% \(\times\) 2750 = 107.25 km\({}^{2}\). If the bottom of the basin (area: 107.25 km\({}^{2}\)) is not treated with anti-seepage, the situation would be drastically different. Considering the hydrogeological parameters such as the permeability coefficient of the soil layer in the local vadose zone, the buried depth of the groundwater level, and the water level of lakes and rivers, the amount of seepage water is calculated to be 14.53 million m\({}^{3}\)/d. The results show that the water ecological engineering based on this concept is very beneficial to the prevention and control of flood disasters.