农业工程学报
農業工程學報
농업공정학보
2015年
15期
124-132
,共9页
杨丹%熊东红%张宝军%郭敏%郑学用%张素
楊丹%熊東紅%張寶軍%郭敏%鄭學用%張素
양단%웅동홍%장보군%곽민%정학용%장소
输沙%径流%土壤%冲沟侵蚀%草被带长度%产沙量
輸沙%徑流%土壤%遲溝侵蝕%草被帶長度%產沙量
수사%경류%토양%충구침식%초피대장도%산사량
sediment transport%runoff%soils%gully erosion%grass belt length%sediment yield
金沙江干热河谷冲沟极为发育，水土流失强烈，严重威胁着该区的生态安全和社会经济发展。为探明植被影响径流过程、促进沟床稳定的机理，该研究采用野外放水冲刷试验，研究分析了沟床草被带长度对径流产输沙过程和特征的影响，旨在探明沟床草被影响下径流含沙量和输沙率时空变化规律。结果表明：1）增大草被带长度可有效降低冲沟径流泥沙含量，改变径流泥沙含量的时空分布特征。泥沙含量在时间上呈指数递减趋势，在冲沟径流运动方向上呈增大趋势。沟床草被带越长，泥沙含量在时间上波动性越弱，递减趋势越明显；随沟床草被带长度的增大，径流泥沙含量在沟床径流运动方向上的增大趋势有减缓现象；此外，当草被带长度增加到8 m以后，进一步增加草被带长度对减小径流泥沙含量效果不显著，而对照小区和4 m草被带小区泥沙含量均显著高于草被带长度≥8 m的小区，说明8 m草被带是降低径流泥沙含量的较好配置长度；2）沟床草被带对径流输沙率有减小作用。当草被带长度＜8 m时，径流输沙率高于草被带＞8 m的小区，且在时间上呈先增大后急剧减小而后趋于稳定的变化趋势。当草被带长度≥8 m时，径流输沙率在时间上表现出微弱的降低趋势。试验冲沟径流输沙率均值在空间上沿径流运动方向自冲沟上游至其下游表现出增大趋势，但草被带长度对输沙率在冲沟径流运动方向上的增大过程有较大影响。该研究为植被措施控制冲沟侵蚀提供理论依据。
金沙江榦熱河穀遲溝極為髮育，水土流失彊烈，嚴重威脅著該區的生態安全和社會經濟髮展。為探明植被影響徑流過程、促進溝床穩定的機理，該研究採用野外放水遲刷試驗，研究分析瞭溝床草被帶長度對徑流產輸沙過程和特徵的影響，旨在探明溝床草被影響下徑流含沙量和輸沙率時空變化規律。結果錶明：1）增大草被帶長度可有效降低遲溝徑流泥沙含量，改變徑流泥沙含量的時空分佈特徵。泥沙含量在時間上呈指數遞減趨勢，在遲溝徑流運動方嚮上呈增大趨勢。溝床草被帶越長，泥沙含量在時間上波動性越弱，遞減趨勢越明顯；隨溝床草被帶長度的增大，徑流泥沙含量在溝床徑流運動方嚮上的增大趨勢有減緩現象；此外，噹草被帶長度增加到8 m以後，進一步增加草被帶長度對減小徑流泥沙含量效果不顯著，而對照小區和4 m草被帶小區泥沙含量均顯著高于草被帶長度≥8 m的小區，說明8 m草被帶是降低徑流泥沙含量的較好配置長度；2）溝床草被帶對徑流輸沙率有減小作用。噹草被帶長度＜8 m時，徑流輸沙率高于草被帶＞8 m的小區，且在時間上呈先增大後急劇減小而後趨于穩定的變化趨勢。噹草被帶長度≥8 m時，徑流輸沙率在時間上錶現齣微弱的降低趨勢。試驗遲溝徑流輸沙率均值在空間上沿徑流運動方嚮自遲溝上遊至其下遊錶現齣增大趨勢，但草被帶長度對輸沙率在遲溝徑流運動方嚮上的增大過程有較大影響。該研究為植被措施控製遲溝侵蝕提供理論依據。
금사강간열하곡충구겁위발육，수토류실강렬，엄중위협착해구적생태안전화사회경제발전。위탐명식피영향경류과정、촉진구상은정적궤리，해연구채용야외방수충쇄시험，연구분석료구상초피대장도대경유산수사과정화특정적영향，지재탐명구상초피영향하경류함사량화수사솔시공변화규률。결과표명：1）증대초피대장도가유효강저충구경류니사함량，개변경류니사함량적시공분포특정。니사함량재시간상정지수체감추세，재충구경류운동방향상정증대추세。구상초피대월장，니사함량재시간상파동성월약，체감추세월명현；수구상초피대장도적증대，경류니사함량재구상경류운동방향상적증대추세유감완현상；차외，당초피대장도증가도8 m이후，진일보증가초피대장도대감소경류니사함량효과불현저，이대조소구화4 m초피대소구니사함량균현저고우초피대장도≥8 m적소구，설명8 m초피대시강저경류니사함량적교호배치장도；2）구상초피대대경류수사솔유감소작용。당초피대장도＜8 m시，경류수사솔고우초피대＞8 m적소구，차재시간상정선증대후급극감소이후추우은정적변화추세。당초피대장도≥8 m시，경류수사솔재시간상표현출미약적강저추세。시험충구경류수사솔균치재공간상연경류운동방향자충구상유지기하유표현출증대추세，단초피대장도대수사솔재충구경류운동방향상적증대과정유교대영향。해연구위식피조시공제충구침식제공이론의거。
Permanent gully is well developed in Jinsha Dry-hot valley region in China. The ravine density of this region can be up to 7.4 km/km2 with the maximum soil erosion modulus 1.64×104 t/(km2·a). Gully erosion seriously threatens the ecological security and social-economic development of the region. Vegetation is one of effective measures to cut down soil erosion. In order to explore the mechanism that vegetation affects overflow movement and promotes gradual stability of active permanent gullies, and find out efficient approaches and methodologies to control the development of permanent gullies in this area, a field scouring experiment was carried out between March and April 2013. The study aimed to investigate the impact of grass belt length on runoff sediment yields and transportation process as well as the spatial and temporal distribution characteristics of sediment content and sediment transport rate. Five experimental plots with grass belt length of 0, 4, 8, 12 and 16 m were constructed on an in-situ gully head in the Gully Erosion and Collapse Experimental Station, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences & the Ministry of Water Resources, Chengdu. Observing cross-sections were set in the gully bed every 4 m as well as an observing cross-section in the drainage area in every plot, and the distance between the gully headwall and the observing cross-section in the drainage area was 1 m. In addition, the width of flow section was measured by steel tap, the depth of runoff was measured by straightedge, and the velocity of overland flow was detected by staining method. Furthermore, sediment samples were collected by particular plastic bottles in every observing cross-section, and oven drying method was utilized to determine the sediment content, and sediment transport rate was calculated by sediment content and flow rate of flow cross-section. The results showed that: 1) Increasing grass belt length could not only effectively reduce the sediment content, but also change the spatio-temporal distribution of sediment content; Runoff sediment content decreased in an exponential function with the flushing time and exhibited an increasing trend along with the experimental plots from the upstream drainage area to downstream gully bed; The fluctuation degree of sediment content over the experimental time went through a decrease process with the increase of grass belt length; As the increase of grass belt length, the fitness of sediment content with experimental time became better, that is to say, the downward trend of sediment content became more and more obvious; On the other hand, although the sediment content underwent an increase process, the increasing trend of sediment content became weaker and weaker along with the experimental plots from the upstream drainage area to downstream gully bed; 2) the grass belt could reduce the sediment transport rate; The sediment transport rate in the experimental plots where the grass belt length was less than 8 m were higher than those in plots where the grass belt length was greater than 8 m; Moreover, when the grass belt length was less than 8 m, sediment transport rate exhibited to increase firstly and then change to sharply decrease and then tended to stable over the whole experimental time; However, runoff sediment transport rate had a weakly decreasing trend over the experimental time when the grass belt length was or greater than 8 m; Furthermore, with the increase of grass belt length, runoff transport rate of the same position observing cross-section in every experimental plots tended to decrease; The mean of runoff sediment transport rate of every observing cross-section showed an increasing trend along with the experimental plots from the upstream drainage area to downstream gully bed, while the specific increasing way of sediment transport rate was influenced by the grass belt length. Comparably, 8 m grass belt may be the optimal length for reducing runoff sediment content.
