87 / 2024-01-05 16:02:57

Hydroinformatics application of Catastrophic Flood Assessment in Haihe River Basin

Hydroinformatics application, distributed modeling, “23∙7” catastrophic flood, Haihe river basin

• The purpose of the work

By using hydroinformatics technologies to deeply analyze and trace the causes of the “23∙7” catastrophic flood occurred in Haihe River Basin, to detect the weak points of flood defense and to give technological suggestion for the future flood management in this region.

• The key issue(s) or problem(s) addressed

One of the main challenge for assess this catastrophic flood is how to deal with the big mount of hydro-data and set up the models to represent the progress of this disaster and to evaluate the impacts of flood defense measures.

• The methodology or approach used

In order to deeply understand the progress of this flood disaster, a big mount of data including hourly records in 5302 rainfall stations, 1385 hydrological stations, 1239 reservoirs and high resolution topography data and 3D hydraulic structures information has been analyzed and applied for setting up the distributed hydrological model of 173 computation unit which covers around 23,000km² area. Moreover, 8 high resolution 2D hydraulic models have been also created for represent the flow movement in the floodplain area. At the end, all those data and modelling results have been integrated into a digital twin platform of Haihe river basin.

• The results or conclusions derived from the research/project/practices

(1) The rainstorm is concentrated certain places of the Haihe River Basin with high rainfall indensity. The catchments covered by the rainstorm presents an obvious "seepage runoff generation" runoff generation mechanism, and their rainfall-runoff coefficients are generally higher than 0.6, that resulting in a high flood peak at the downstream.

(2) The measured flood peaks at multiple stations in the upstream of the Daqing River Basin have exceeded/approached historical extremes. The designed flood discharge capacity of the Baigou River is only 3000 m³/s, and the current flood discharge capacity is insufficient. The left embankment of Xiaoying dike is only 1m higher than the river channel which is one of the main weak point of the flood defense system of Haihe River basin.

(3) 84 large and medium-sized reservoirs in the basin have intercepted and stored over 2.85 billion m³ of flood, with an average peak shaving rate of 77%. They have reduced flooding in 24 towns and 7.51 million mu of farmland, avoiding the relocation of 4.623 million people. The maximum storage capacity of 8 flood storage and detention areas is 2.53 billion m³, effectively reducing flood peaks and diverting flood volume, greatly reducing the flood control pressure in downstream areas.