低影响开发技术在半山区丘陵地带的应用效果评估

为评估低影响开发技术缓解半山区丘陵地带城市内涝的效用,以河北邢台临城县中心城区为例,结合地理信息系统构建了研究区暴雨洪水管理模型,利用实测节点积水深数据率定了模型参数,验证了模型的可靠性。以此模型为工具,因地制宜布设了各种低影响开发措施,分别对比分析了3a、5a、10a、20a一遇设计暴雨下措施实施前后出水口的流量过程。结果表明:在半山区,低影响开发措施可以改变区域径流过程,使出水口流量过程线较为坦化,起涨时间明显滞后,洪峰平缓。但上述变化均受坡度影响,且消峰减量效果不仅与布设面积有关,还与坡度有关,坡度越小消减效果越明显。洪水总量及洪峰流量消减率随重现期的增大逐渐减小,且控制洪水总量的敏感性优于洪峰;措施实施的滞峰效果和滞峰能力均不明显。研究结果可为区域内开展小尺度海绵措施改造提供决策支持,为其他半山区域的雨洪管理提供参考。

Evaluation on application of low impact development technology in hilly zone of semi-mountainous region

n order to assess the effectiveness of low impact development ( LID) technologies for mitigating urban waterlogging in the hilly zone of semi-mountainous region， the central urban area in Lincheng County of Xingtai City in Hebei Province is taken as a study case，and then a rainstorm flood management model is established in combination with the Geographic Information System，while the model parameters are calibrated with the waterlogging data from the relevant measured nodes， thus the reliability of the model is verified. By taking this model as the tool，various LID measures are deployed according to the relevant local conditions，and then the water outlet hydrographs of the design rainstorms with the return-periods of 3a，5a，10a and 20a before and after implementing the measures are analyzed respectively. The result shows that the LID measures can change the regional runoff process in semi-mountainous region and make the outlet hydrograph more flattening with significant delay of fluctuating time and smooth flood peak. However，all the changes mentioned above are affected by slope gradient，while the effect of peak clipping and volume reduction is not only related to the measure deploying area，but also related to slope gradient，thus the smaller the slope gradient is， the more significant the flood reduction effect is to be. Both the flood volume and the flood peak flow gradually decrease along with the increase of the return period，while the sensitivity of controlling flood volume is better than that of flood peak，but the effect and capacity of flood peak retardation from implementing the measures are not obvious. The study result can not only provide decision-making support for carrying out the improvement with smallscale sponge measures within the region，but also can provide reference for the rainflood management in the other semi-mountainous regions.