柽柳灌丛沙堆及丘间地蚀积分布随背景植被变化的风洞实验
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摘要
以塔克拉玛干沙漠南缘沙漠—绿洲过渡带广泛分布的柽柳灌丛沙堆及丘间地植物为原型,依据风沙运动相似理论,制作背景植被盖度依次为0%、4%、10%、16%和26%五组灌丛沙堆模型,在风洞中进行蚀积变化规律模拟实验。结果表明:柽柳灌丛沙堆及丘间地蚀积分布可划分为6个区域,依次为沙堆前积沙区、沙堆迎风坡风蚀区、沙堆两侧风蚀区、沙堆背风侧涡流积沙区、沙堆后尾流积沙区和不受沙堆影响区。随着指示风速增大,沙堆前积沙区和尾流积沙区范围缩小而沙堆两侧风蚀区面积明显增大。随着背景植被盖度的增大,沙堆前积沙区和尾流积沙区范围增大而沙堆两侧风蚀区范围明显减小。灌丛沙堆及丘间地整体风蚀面积比、风蚀率、各分区蚀积强度均呈指数规律递减。背景植被盖度为0%时,灌丛沙堆影响区风蚀率明显高于不受沙堆影响区,说明裸露地表条件下灌丛沙堆的存在会加剧地表风蚀;当背景植被盖度为4%~16%时,灌丛沙堆影响区风蚀率均低于不受沙堆影响区,可见丘间地植被存在可使灌丛沙堆起到一定的防风阻沙作用。当背景植被盖度>16%时,柽柳灌丛沙堆及丘间地整体蚀积强度和风蚀率变化趋于平稳。据此认为维持不低于16%的背景植被覆盖,是沙漠—绿洲过渡带柽柳灌丛沙堆科学保育的关键。
Based on the similarity theory of wind and sand movement,the study took the Tamarix nebkhas and interdune plants,which are widely distributed in Oasis-desert ecotone at the southern rim of the Taklimakan Desert,as the research prototype to create five sets of nebkhas model with background vegetation coverage of 0%,4%,10%,16%,26%,respectively to conduct the simulation experiment of erosion and accumulation change rule in the wind tunnel. The results show that: erosion and deposition distributions among Tamarix ramosissima nebkhas and interdune can be divided into six areas: depositional area in front of nebkhas,the eroded area on nebkhas' windward slope,the eroded area on nebkhas' both sides,the vortex depositional area on nebkhas' leeward side,the wake depositional area behind the nebkhas and the unaffected area. Along with the increase of the wind speed,range of frontal depositional area and wake depositional area shrinks while that of the eroded land on nebkhas' both sides decreases significantly. In addition,along with the increase of background vegetation cover range of frontal depositional area and wake depositional area increased while that of eroded land on nebkhas' both sides decreases significantly. The entirety erosion area ratio,the wind erosion rate and the erosion/accumulation intensity on the partitions are all decreasing with exponential law. When the background vegetation coverage equals to 0%,wind erosion rate in nebkhas-affected area is obviously higher than that non-nebkhas-affected area,which indicates that the presence of nebkhas will increase the wind erosion on bare surface. When the background vegetation coverage equals to 4%-16%,the wind erosion rate of the nebkhas-affected area was lower than that of the non-nebkhas-affected area,which means that the presence of interdune vegetation around nebkhas could,to a certain degree,make contribution to wind breaking and sand blocking. When the background vegetation cover is over 16%,change of the erosion intensity and wind erosion rate of Tamarix ramosissima nebkhas and interdune become level off. It is considered that keeping the background vegetation coverage not less than 16% is the key to the scientific conservation of the Tamarix nebkhas in the Oasis-desert ecotone.
Based on the similarity theory of wind and sand movement,the study took the Tamarix nebkhas and interdune plants,which are widely distributed in Oasis-desert ecotone at the southern rim of the Taklimakan Desert,as the research prototype to create five sets of nebkhas model with background vegetation coverage of 0%,4%,10%,16%,26%,respectively to conduct the simulation experiment of erosion and accumulation change rule in the wind tunnel. The results show that: erosion and deposition distributions among Tamarix ramosissima nebkhas and interdune can be divided into six areas: depositional area in front of nebkhas,the eroded area on nebkhas' windward slope,the eroded area on nebkhas' both sides,the vortex depositional area on nebkhas' leeward side,the wake depositional area behind the nebkhas and the unaffected area. Along with the increase of the wind speed,range of frontal depositional area and wake depositional area shrinks while that of the eroded land on nebkhas' both sides decreases significantly. In addition,along with the increase of background vegetation cover range of frontal depositional area and wake depositional area increased while that of eroded land on nebkhas' both sides decreases significantly. The entirety erosion area ratio,the wind erosion rate and the erosion/accumulation intensity on the partitions are all decreasing with exponential law. When the background vegetation coverage equals to 0%,wind erosion rate in nebkhas-affected area is obviously higher than that non-nebkhas-affected area,which indicates that the presence of nebkhas will increase the wind erosion on bare surface. When the background vegetation coverage equals to 4%-16%,the wind erosion rate of the nebkhas-affected area was lower than that of the non-nebkhas-affected area,which means that the presence of interdune vegetation around nebkhas could,to a certain degree,make contribution to wind breaking and sand blocking. When the background vegetation cover is over 16%,change of the erosion intensity and wind erosion rate of Tamarix ramosissima nebkhas and interdune become level off. It is considered that keeping the background vegetation coverage not less than 16% is the key to the scientific conservation of the Tamarix nebkhas in the Oasis-desert ecotone.
引文
[1]COOKE R,WARREN A,GOUDIE A.Desert geomorphology[M].London:UCL Press,1993.
[2]TSOAR H.Types of aeolian sand dunes and their formation[J].2008,582:403-429.
[3]TENGBERG A,CHEN D L.A comparative analysis of nebkhas in central Tunisia and northern Burkina Faso[J].Geomorphology,1998,22(2):181-192.
[4]杜建会,严平,董玉祥.干旱地区灌丛沙堆研究现状与展望[J].地理学报,2010,65(3):339-350.[DU Jianhui,YAN Ping,DONG Yuxiang,et al.The progress and prospects of nebkhas in arid areas[J].Journal of Geographical Sciences,2010,65(3):339-350.]
[5]樊自立.塔里木盆地绿洲形成与演变[J].地理学报,1993,(5):421-427.[FAN Zili.A study on the formation and evolution of oases in Tarim Basin[J].Journal of Geographical Sciences,1993,(5):421-427.]
[6]BRUELHEIDE H,JANDT U,GRIES D,et al.Vegetation changes in a river oasis on the southern rim of the Taklamakan Desert in China between 1956 and 2000.[J].Phytocoenologia,2003,33(4):801-818.
[7]ARDON K,TSOAR H,BLUMBERG D G.Dynamics of nebkhas superimposed on a parabolic dune and their effect on the dune dynamics[J].Journal of Arid Environments,2009,73(11):1014-1022.
[8]WASSON R J,NANNINGA P M.Estimating wind transport of sand on vegetated surfaces[J].Earth Surface Processes&Landforms,1986,11(5):505-514.
[9]李志忠,武胜利,王晓峰,等.新疆和田河流域柽柳沙堆的生物地貌发育过程[J].地理学报,2007,62(5):462-470.[LI Zhizhong,WU Shengli,WANG Xiaofeng,et al.Bio-geomorphologic growth process of Tamarix nabkha in the Hotan River Basin of Xinjiang[J].Journal of Geographical Sciences,2007,62(5):462-470.]
[10]李志忠,武胜利,肖晨曦,等.新疆和田河流域灌丛沙堆风洞流场的实验研究(Ⅰ)[J].中国沙漠,2007,27(1):9-14.[LI Zhizhong,WU Shengli,XIAO Chenxi,et al.Study on wind-tunnel simulated flow pattern over nabkha in Hetian River Basin,Xinjiang(Ⅰ)[J].Journal of Desert Research,2007,27(1):9-14.]
[11]哈斯,杜会石,孙禹.内蒙古高原小叶锦鸡儿(Caragana microphylla)灌丛沙丘:形态特征及表面气流[J].第四纪研究,2013,33(2):314-324.[HASI Eerdun,DU Huishi,SUN Yu.Caragana microphylla nebkhas in Inner Mongolia Plateau:morphology and surface airflow[J].Quaternary Sciences,2013,33(2):314-324.]
[12]LEENDERS J K,BOXEL J H V,STERK G.The effect of single vegetation elements on wind speed and sediment transport in the Sahelian Zone of Burkina Faso[J].Earth Surface Processes and Landforms,2007,32(10):1454-1474.
[13]杨帆,郑新倩,王雪芹,等.绿洲—沙漠过渡带柽柳灌丛沙堆表面的蚀积特征[J].沙漠与绿洲气象,2013,7(5):55-61.[YANG Fan,ZHENG Xinqian,WANG Xueqin,et al.The surface erosion-deposition characteristic of Tamarix ramosissima nebkhas in cele oasis-desert ecotone[J].Desert and Oasis Meteorology,2013,7(5):55-61.]
[14]张春来,邹学勇,董光荣,等.植被对土壤风蚀影响的风洞实验研究[J].水土保持学报,2003,17(3):31-33.[ZHANG Chunlai,ZOU Xueyong,DONG Guangrong,et al.Wind tunnel studies on influences of vegetation on soil wind erosion[J].Journal of Soil and Water Conservation,2003,17(3):31-33.]
[15]WHITE B R.Laboratory simulation of aeolian sand transport and physical modeling of flow around dunes[J].Annals of Arid Zone,1996,35(3):187-213.
[16]ZHANG W,KANG J H,LEE S J.Tracking of saltating sand trajectories over a flat surface embedded in an atmospheric boundary layer[J].Geomorphology,2007,86(s 3-4):320-331.
[17]张萍,哈斯,吴霞,等.单个油蒿灌丛沙堆气流结构的野外观测研究[J].应用基础与工程科学学报,2013,21(5):881-889.[ZHANG Ping,HASI Eerdun,WU Xia,et al.Filed investigation on airflow profile of an Artemisia ordosica nebkha dune[J].Journal of Basic Science and Engineering,2013,21(5):881-889.]
[18]DONG Z,LUO W,QIAN G,et al.Wind tunnel simulation of the three-dimensional airflow patterns around shrubs[J].Journal of Geophysical Research Atmospheres,2008,113(F2):139-139.
[19]董治宝,陈渭南,董光荣,等.植被对风沙土风蚀作用的影响[J].环境科学学报,1996,16(4):437-443.[DONG Zhibao,CHEN Weinan,DONG Guangrong,et al.Influences of vegetation cover on the wind erosion of sandy soil[J].Acta Scientiae Circumstantiae,1996,16(4):437-443.]
[20]BURRI K,GROMKE C,LEHNING M,et al.Aeolian sediment transport over vegetation canopies:a wind tunnel study with live plants[J].Aeolian Research,2011,3(3):205-213.
[21]ZOU X,LI J,LIU B,et al.The protective effects of nebkhas on an oasis[J].Aeolian Research,2016,20:71-79.
[22]LUO W,ZHAO W,LIU B.Growth stages affect species richness and vegetation patterns of nebkhas in the desert steppes of China[J].Catena,2016,137:126-133.
[23]刘进辉,王雪芹,马洋,等.绿洲沙漠过渡带柽柳灌丛沙堆-丘间地系统土壤粒度分异规律研究[J].北京林业大学学报,2015,37(11):89-99.[LIU Jinhui,WANG Xueqin,MA Yang,et al.Spatial heterogeneity of soil grain size on Tamarix ramosissima nebkhas and interdune in desert-oasis ecotone[J].Journal of Beijing Forestry University,2015,37(11):89-99.]
[2]TSOAR H.Types of aeolian sand dunes and their formation[J].2008,582:403-429.
[3]TENGBERG A,CHEN D L.A comparative analysis of nebkhas in central Tunisia and northern Burkina Faso[J].Geomorphology,1998,22(2):181-192.
[4]杜建会,严平,董玉祥.干旱地区灌丛沙堆研究现状与展望[J].地理学报,2010,65(3):339-350.[DU Jianhui,YAN Ping,DONG Yuxiang,et al.The progress and prospects of nebkhas in arid areas[J].Journal of Geographical Sciences,2010,65(3):339-350.]
[5]樊自立.塔里木盆地绿洲形成与演变[J].地理学报,1993,(5):421-427.[FAN Zili.A study on the formation and evolution of oases in Tarim Basin[J].Journal of Geographical Sciences,1993,(5):421-427.]
[6]BRUELHEIDE H,JANDT U,GRIES D,et al.Vegetation changes in a river oasis on the southern rim of the Taklamakan Desert in China between 1956 and 2000.[J].Phytocoenologia,2003,33(4):801-818.
[7]ARDON K,TSOAR H,BLUMBERG D G.Dynamics of nebkhas superimposed on a parabolic dune and their effect on the dune dynamics[J].Journal of Arid Environments,2009,73(11):1014-1022.
[8]WASSON R J,NANNINGA P M.Estimating wind transport of sand on vegetated surfaces[J].Earth Surface Processes&Landforms,1986,11(5):505-514.
[9]李志忠,武胜利,王晓峰,等.新疆和田河流域柽柳沙堆的生物地貌发育过程[J].地理学报,2007,62(5):462-470.[LI Zhizhong,WU Shengli,WANG Xiaofeng,et al.Bio-geomorphologic growth process of Tamarix nabkha in the Hotan River Basin of Xinjiang[J].Journal of Geographical Sciences,2007,62(5):462-470.]
[10]李志忠,武胜利,肖晨曦,等.新疆和田河流域灌丛沙堆风洞流场的实验研究(Ⅰ)[J].中国沙漠,2007,27(1):9-14.[LI Zhizhong,WU Shengli,XIAO Chenxi,et al.Study on wind-tunnel simulated flow pattern over nabkha in Hetian River Basin,Xinjiang(Ⅰ)[J].Journal of Desert Research,2007,27(1):9-14.]
[11]哈斯,杜会石,孙禹.内蒙古高原小叶锦鸡儿(Caragana microphylla)灌丛沙丘:形态特征及表面气流[J].第四纪研究,2013,33(2):314-324.[HASI Eerdun,DU Huishi,SUN Yu.Caragana microphylla nebkhas in Inner Mongolia Plateau:morphology and surface airflow[J].Quaternary Sciences,2013,33(2):314-324.]
[12]LEENDERS J K,BOXEL J H V,STERK G.The effect of single vegetation elements on wind speed and sediment transport in the Sahelian Zone of Burkina Faso[J].Earth Surface Processes and Landforms,2007,32(10):1454-1474.
[13]杨帆,郑新倩,王雪芹,等.绿洲—沙漠过渡带柽柳灌丛沙堆表面的蚀积特征[J].沙漠与绿洲气象,2013,7(5):55-61.[YANG Fan,ZHENG Xinqian,WANG Xueqin,et al.The surface erosion-deposition characteristic of Tamarix ramosissima nebkhas in cele oasis-desert ecotone[J].Desert and Oasis Meteorology,2013,7(5):55-61.]
[14]张春来,邹学勇,董光荣,等.植被对土壤风蚀影响的风洞实验研究[J].水土保持学报,2003,17(3):31-33.[ZHANG Chunlai,ZOU Xueyong,DONG Guangrong,et al.Wind tunnel studies on influences of vegetation on soil wind erosion[J].Journal of Soil and Water Conservation,2003,17(3):31-33.]
[15]WHITE B R.Laboratory simulation of aeolian sand transport and physical modeling of flow around dunes[J].Annals of Arid Zone,1996,35(3):187-213.
[16]ZHANG W,KANG J H,LEE S J.Tracking of saltating sand trajectories over a flat surface embedded in an atmospheric boundary layer[J].Geomorphology,2007,86(s 3-4):320-331.
[17]张萍,哈斯,吴霞,等.单个油蒿灌丛沙堆气流结构的野外观测研究[J].应用基础与工程科学学报,2013,21(5):881-889.[ZHANG Ping,HASI Eerdun,WU Xia,et al.Filed investigation on airflow profile of an Artemisia ordosica nebkha dune[J].Journal of Basic Science and Engineering,2013,21(5):881-889.]
[18]DONG Z,LUO W,QIAN G,et al.Wind tunnel simulation of the three-dimensional airflow patterns around shrubs[J].Journal of Geophysical Research Atmospheres,2008,113(F2):139-139.
[19]董治宝,陈渭南,董光荣,等.植被对风沙土风蚀作用的影响[J].环境科学学报,1996,16(4):437-443.[DONG Zhibao,CHEN Weinan,DONG Guangrong,et al.Influences of vegetation cover on the wind erosion of sandy soil[J].Acta Scientiae Circumstantiae,1996,16(4):437-443.]
[20]BURRI K,GROMKE C,LEHNING M,et al.Aeolian sediment transport over vegetation canopies:a wind tunnel study with live plants[J].Aeolian Research,2011,3(3):205-213.
[21]ZOU X,LI J,LIU B,et al.The protective effects of nebkhas on an oasis[J].Aeolian Research,2016,20:71-79.
[22]LUO W,ZHAO W,LIU B.Growth stages affect species richness and vegetation patterns of nebkhas in the desert steppes of China[J].Catena,2016,137:126-133.
[23]刘进辉,王雪芹,马洋,等.绿洲沙漠过渡带柽柳灌丛沙堆-丘间地系统土壤粒度分异规律研究[J].北京林业大学学报,2015,37(11):89-99.[LIU Jinhui,WANG Xueqin,MA Yang,et al.Spatial heterogeneity of soil grain size on Tamarix ramosissima nebkhas and interdune in desert-oasis ecotone[J].Journal of Beijing Forestry University,2015,37(11):89-99.]
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