风沙活动强度3种估算指标对比及适用性分析

Applicability of three indexes for estimating the intensity of blown-sand activity

风沙活动强度是风沙地区交通、能源基地等基础设施建设和运营中科学开展风沙工程防护设计须考虑的重要内容。但在实际工作中尚缺乏操作性强、适用性广的风沙活动强度估算指标。本研究选取风蚀气候侵蚀力、沙丘活化指数和输沙势3种常用指标,基于中国北方风沙区多个具体工程案例,对比分析了3种指标的适宜性及存在问题。结果表明:(1)由于没有考虑工程周边沙源丰富程度的相关影响因素(如植被、戈壁砾石的覆盖度),3种指标的估算结果均难以准确客观地反映具体工程的实际风沙问题。(2)采用高精度风速风向数据计算的输沙势更能表达干旱地区的风沙活动特征,但在降水较多的区域偏差较大。(3)铁路等线性工程两侧风沙活动强度可能存在差异,相同防沙措施的防护效益存在明显差别,具体工程风沙活动强度的估算应明确其方向性差异。在指导防护体系建设时,需尽可能考虑降水、气温、风速、风向等多种因子,同时结合沙源、地表覆盖度、工程走向等实际情况来分析风沙活动强度差异。研究结果有助于提出一种准确度高、适用性广、可操作性强的风沙活动强度估算指标,为有效开展防沙工程设计提供指导。

For the construction and operation of transportation and energy infrastructure in sandy area,the intensity of blown-sand activity is an important index that should be considered in designing wind-blown sand control engineering.However,currently there is no easily and widely adopted method to calculate this intensity.In this study,three commonly used indicators,namely wind erosion climatic erosivity,dune activity index and sand drift potential,were selected to compare and analyze the suitability and existing problems of each index after referring multiple specific engineering cases in North China.The results are as follows.(1)Without considering the relevant factors affecting the availability of sand sources around the engineering,such as the coverage of vegetation and gobi gravel,the three indicators cannot reflect the actual wind and sand problems of specific engineering.(2)The sand drift potential calculated using high-precision wind speed and direction data can better express the wind characteristics in arid areas,but its deviation is larger in regions with more precipitation.(3)Significant differences in the intensity of blown-sand activity may exist on two sides of linear engineering such as railways,and there are obvious differences in the protection effects of the same sand control measure.The difference of direction should be made clear when estimating the intensity of blown-sand activity for a specific project.When guiding the construction of the protection system,it is necessary to consider as many climatic factors as possible,such as precipitation,air temperature,wind speed and wind direction.The difference of sand activity intensity,the availability of sand source,the surface coverage,and engineering trend should be take into account together.The study is helpful to propose a method for estimating the intensity of blown-sand activity with high accuracy,wide applicability and good operability in the future,which will provides guidance for the effective design of sand control engineerings.