基于模糊评价模型的南水北调中线冰害风险空间分布

Spatial distribution of ice hazards in middle route of South-to-North Water Transfer Project based on fuzzy evaluation model

南水北调中线工程线路长、跨越纬度大,冬季输水时存在发生冰塞、冰坝的风险,其中冰塞、冰坝堆积风险、开河模式规律等随渠道地理条件如:弯曲、横断面宽度等的变化而变化。因此亟需对风险的空间分布进行研究,以便于实现对渠道的分级管理,节省运营成本,增加工程应对风险的能力。应用模糊评价理论,通过分析、量化渠道地理条件,建立风险评价指标体系与评估模型,获得了冰害风险的空间分布。首先分析获得纵向坡度、弯曲、横断面束窄及渠道障碍物四个易诱发渠道冰害的地理条件;之后基于冰塞产生机理改进了地理条件的量化方法,并构建了冰害风险评价指标体系;然后以京石段为例,采用等距分割的方法获得多个单元渠道,并采用模糊评价模型评估每个单元渠道的风险;最后基于单元渠道的风险分布评估京石段不同渠段的风险。结果表明:单元渠道的冰害风险可分为5级;西黑山节制闸-瀑河倒虹吸节制闸渠段及坟庄河节制闸-南拒马节制闸渠段的相对风险最大,研究结果对冰害防治具有一定的指导意义。

The middle route of the South-to-North Water Transfer project is long and runs across a wide range of altitudes,and it will suffer from the risks of ice clogging and damming during the freezing period.The risk of ice jam accumulation as well as the break-up pattern vary with the tortuosity,cross-section width and other geographical conditions of the channel.Therefore,it is necessary to study the spatial distribution of the ice hazards in order to realize hierarchical management of channels,save operating costs and increase the ability to deal with risks.This paper established a risk evaluation index system and evaluation model to obtain the spatial distribution of the ice hazards by quantifying the channel′s geographical conditions based on the fuzzy evaluation theory.First,four geographical indicators that predispose to ice hazards were obtained including longitudinal slope,tortuosity of channel,cross-section width and obstacles.And then,the quantitative method for geographical conditions was improved based on the mechanism of ice jam formation,and the risk evaluation index system was established.Lastly,the Beijing-Shijiazhuang section was taken as a case study,in which the risks of different canal reaches were evaluated with the proposed model by partitioning the section into multiple unit channels.Results showed that the ice hazards of a unit channel can fall into five levels,and the hazards are the largest in the Xihei Mountain Regulator-Baohe River Regulator Reach and Fenzhuang River Regulator-Nanjuma Regulator Reach.The research findings can offer some valuable guidance to ice damage prevention and control.