可降解格状沙障对典型新月形沙丘风沙活动调控作用研究OA

The Yabulai Mountain wind-sand gap,the largest convergence zone between the Badain Jaran Desert and the Tengger Desert,is subject to intense aeolian activity with complex sediment transport pathways,making it a critical area for the Three-North Shelterbelt Project.Through multi-profile gradient synchronous observations of wind and sand conducted at the foot,mid-slope,and crest of the windward slope of crescent-shaped dunes in this region,this study compares the structural characteristics of sand transport flows and the particle size differen-tiation patterns of wind-eroded sediments between biodegradable poly lactic acid(PLA)sand barriers and bare sand surfaces.The results indicate the following:(1)PLA sand barriers markedly suppress mid-to-high-level sedi-ment transport at the slope base(sediment-free above 30 cm).Sediment reduction rates at the mid-slope and crest reach 53%,although near-surface sediment transport remains high.The wind-sand flow structure in PLA sand bar-rier zones at the slope base and mid-slope shows an inflection point at 0-10 cm,deviating from the typical expo-nential decay trend.(2)Sediment transport at the base and crest of PLA sand barrier zones occurs primarily with-in the 0-30 cm range,whereas bare sand crests concentrate transport within 0-20 cm(accounting for 85%).Bare sand at the base and mid-slope,along with PLA sand barriers at the mid-slope,exhibit sediment transport across the full 0-100 cm range.(3)The particle size distribution of wind-eroded material falls primarily between 100 and 500 μm,with saltation as the dominant transport mechanism(volume fraction>95%).At the bare sand slope crest,the proportion of suspended particles increased markedly to approximately 25%within the 2-10 cm range,whereas suspended transport at the same elevation on the bare sand mid-slope accounted for only about 4%.At the mid-slope,transport occurred primarily via saltation within the 50-100 cm range,accompanied by minor sus-pended transport(approximately 8%)and creep transport(approximately 5%).The cumulative distribution curves for PLA sand barriers exhibit consistent patterns,with particle motion dominated by saltation.(4)The average grain size of wind-eroded material shows a fluctuating decrease with increasing elevation,indicating good sort-ing.The distribution displays moderate kurtosis and near-symmetric skewness.(5)PLA sand barriers produce a central erosion-type single-funnel concave surface at the slope base and mid-slope,while the slope crest develops a northwest-trending accumulation ridge and a double-funnel concave structure.Considerable gradient differenc-es in erosion and accumulation depths are observed across different slope positions.PLA sand barriers effectively suppress dune migration by altering near-surface wind-sand flow structures and sediment grain size composition,providing data support for ecological protection at wind-sand convergence zones.