293 / 2024-02-29 09:16:36

Simulation of Runoff Yield in Drainage Areas based on SCS and MIKE11 Coupling

SCS model; MIKE11model; drainage area; runoff simulation

The accurate simulation of the process of runoff yield in the drainage area is important for determining the appropriate design scale and orderly operation of waterlogging control projects. Taking the Luoshan drainage area in Four-lake Watershed in Hubei Province in China as an example, on the basis of widely collected data such as rainfall, land use, soil type, river section, water level and flow and so on, a coupled runoff yield model in the drainage area was developed by combining SCS with MIKE11. SCS can simulate the runoff well, but it does not reflect the flow concentration process of drainage systems such as rivers, canals, pumps and sluices. While MIKE11 has good performance in river routing simulation, it performs poorly for runoff simulation because it does not consider the space variability of parameters, and has many parameters that are difficult to obtain by observation. While the runoff of paddy field and water surface and the simulation of sluice and pump are modified.The model was calibrated and validated by the measured water level data at Luoshan pumping station in 1980, 1983, 1991 and 1996. Then the CN and roughness coefficient of the model are calibrated and validated. During the calibration periods (1980 and 1983), the relative errors between the simulated and observed water levels were -0.20% and -0.40%, respectively. The corresponding correlation coefficients were 0.980 and 0.952. And the efficiency coefficients were 0.949 and 0.849. Over the validation periods (1991 and 1996), the relative errors between the simulated and observed water levels were -0.10% and 1.70%. The correlation coefficients were 0.919 and 0.967. And the efficiency coefficients were 0.782 and 0.906, respectively. The agreement between simulated and observed data indicates that the coupled model is effective in simulating the process of runoff yield in the Luoshan drainage area. The model was used to evaluate the drainage capacity of the area. The current drainage capacity only meets a drainage standard with return periods of 7.1 years. If the standard is to be improved to meet that with return periods of 10 years, the discharge capacity should be increased from the current value of 150 m3/s to 161 m3/s. In addition, the influence of flood level of the outer river to drainage is analyzed quantitatively by simulating drainage modulus under the combination of different design storm and flood level of the outer river.