溃口宽度和倒灌、退水对防洪保护区洪水演进的影响

Effect of levee-breach width and water intrusion and recession on flood routine in flood protected zone

考虑沟渠倒灌、退水对防洪保护区溃堤洪水演进的影响,采用有限体积法建立了防洪保护区的二维洪水演进模型,分别采用二阶TVD格式和二阶Runge-Kutta方法对计算区域的空间离散和时间离散求解,定量分析了溃口宽度和沟渠倒灌、退水对防洪保护区洪水演进及淹没范围的影响,并用水面线平铺得到的淹没线对模型计算淹没范围进行了验证。研究表明:溃口宽度每增加50m,区内蓄洪量相差8%左右,溃口越宽,水位上涨越高,但最大水深随时间的变化不明显,淹没范围的变化率较小,最大淹没范围相差约1.8%;沟渠退水和支流倒灌的作用非常明显,最大蓄洪量和最大淹没范围相差60%以上。与溃口宽度增大相比,沟渠倒灌、退水会造成更大的淹没损失。

The paper built 2D model by using finite volume method （FVM） to analyze the effect of water intrusion and recession on levee-breach flood routine in flood protected zone quantitatively. It solved the space discretization and time discretization of calculation region by second-order TVD format and secondorder Runge-Kutta method,and quantitatively analyzed the influence of water intrusion and recession on levee-breach flood routine and immerse scope in flood protected zone. The calculated submerged scope of the model is verified. The results show that when the levee-breach width increase 50 meters the flood storage quantity of flood protected zone decreases 8 percent. With the increase of breach width, the water level rises, but the maximum water depth does not change significantly with change of time. The change rate of submerged area is less, and the largest submerged area differs by 1.8 %. The effect of water intrusion and recession is very obvious, the difference between the maximum flood volume and maximum submerged area is more than 60%. Water intrusion and recession will cause greater flood losses compared with the increase of levee-breach width in flood protected zone.