一种基于稳定流场的流域径流汇流模拟方法

A Basin Runoff Simulation Modal Based on Steady Flow Fields

近年来,人类活动导致气候异常,暴雨洪涝灾害频发。建立有效的径流汇流模型模拟流域径流过程具有重要意义。然而,流域前期水情误差成为进一步提高模拟精度的瓶颈。为此,以纳维-斯托克斯方程(N-S方程)为指导,提出一种基于稳定流场的流域径流汇流模型模拟方法。首先,通过对N-S方程分解,建立了栅格模式下的径流汇流模型;然后,针对模型存在"汇流水流方向异常"问题,加入水流混合模拟环节,包括栅格单元水速增量修正和邻域栅格单元水流混合模拟。实验表明,当上游供水稳定时,模型能产生稳定的水流场;最后,以岷江上游为实验流域,将模拟时段24 h前的小时上游流量代入模型创建稳定流场,模拟流域前期水情;利用600 h的实测降水数据和上游流量数据进行径流汇流模拟,获取流域出口水文站的模拟水位序列,并与实测水位对比,发现算法能提高流域径流模拟精度,在暴雨洪涝灾害的预警预报中具有一定的理论意义和实践价值。

In recent years, human activities have led to climate anomalies and frequent rainstorms and floods. It is of great significance to establish an effective runoff model to simulate the basin runoff process. However, the errors of prophase water regime have become a key bottleneck to further improve the accuracy of runoff simulation. To simulate the basin prophase water regime more accurately, a runoff simulation model based on steady flow field is proposed under the guidance of Navier-Stokes Equation. In order to solve the problem of "abnormal direction of water flow" in the model, the mixed flow simulation is added to the modal, which includes water velocity increment correction and mixing simulation with neighborhood. It is proved that the new algorithm can produce a stable water flow when the upstream has a stable water supply. On this basis, a certain amount of upstream flow sequences and area precipitation sequence before the simulation period are imported to the model to produce prophase water regime. Finally, taking the upper reaches of Minjiang River as the experimental basin, the steady flow field is created by substituting the upstream flow of 24 hours before the simulation period into the model to simulate prophase water regime of the basin. 600 hours of measured precipitation data and upstream flow data are used to simulate runoff confluence, the simulated water level series of the hydrological station at the outlet of the basin are obtained. Compared with the measured water level, it is found that the proposed method can improve the accuracy of runoff simulation in the basin and has a certain theoretical significance and practical value in the early warning and forecasting of rainstorm and flood disasters.