乌兰布和沙漠黄河段不同治理措施固沙效果研究

Sand-fixing Effects of Different Management Measures in the Yellow River Section of Wulanbuhe Desert

以乌兰布和沙漠沿黄段为研究区,研究了麦草沙障、沙柳沙障和梭梭林3种治理措施下风速廓线、粗糙度、风沙流结构及输沙率等指标的变化,以期筛选不同治理措施下防风固沙效果的优劣性,为进一步完善当地防沙护岸和防沙治沙工程提供一定理论依据。结果表明:梭梭林地和设置沙障后的近地表(0~30 cm)粗糙度较流动沙丘明显增加,风速明显降低,且沙障的风速廓线随高度均遵循对数分布规律。铺设沙障后或营造梭梭固沙林,输沙率相比流沙均有明显降低,相同风速下铺设沙柳沙障后输沙率为流沙的2.2%~38.2%,铺设麦草沙障后输沙率为流沙的13.3%~35.8%,梭梭林地输沙率为流沙的4.2%~27.6%。随风速的增加,流动沙丘风沙流结构特征值λ逐渐减小,麦草沙障风沙流结构特征值λ逐渐增大,沙柳沙障和梭梭林风沙流结构特征值λ呈现先减小后增加的规律。采取措施后下垫面均能很好地控制近地表的流沙活动。

Taking the Yellow River section of Wulanbuhe Desert as research area,wind profile,surface roughness,sand flow structure and sediment transport rate have been studied under straw sand barrier,Salix psammophila sand barrier and Haloxylon ammodendron,in order to select the wind-preventing and sand-fixing effects of different management measures and provide the theoretical basis for improving the local sand control engineering.The results show that the roughness near surface(0~30 cm)in forestland of Haloxylon ammodendron and after establishing sand barrier has been increased more obviously than that of moving dunes,the wind speed has been reduced obviously,and the wind profile of sand barrier has followed the logarithmic distribution with height.After planting Haloxylon ammodendron and establishing sand barrier,sediment transport rate has been reduced obviously than that of moving dune.At same wind speed,the sediment transport rate after establishing Salix psammophila sand barrier is 2.2%~38.2%of that of moving dune,the one after establishing straw sand barrier is13.3%~35.8%of that of moving dune,the one of forestland of Haloxylon ammodendron is 4.2%~27.6%of that of moving dune.With wind speed increasing,the characteristic value(λ)of moving dune has decreased gradually,the one of straw sand barrier has risen gradually,and the ones of Salix psammophila sand barrier and Haloxylon ammodendron have showed a tendency of first decreasing and then increasing.After taking measures,underlying surface can control shifting sand movement near surface well.