人工羊草地的水土保持效应研究

发布时间：2018-06-09 15:07

本文选题：羊草 + 盖度　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：黄土高原地区植被覆盖度低,土壤抗侵蚀能力弱,加之降雨分布集中,造成严重的水土流失,土地资源遭受破坏,导致土壤肥力下降,生态环境极为脆弱。植被对土壤侵蚀的影响具有不可忽视的作用,退耕建植人工草地可以明显减轻土壤侵蚀程度,有利于土壤在雨季对降水的蓄积。羊草在我国集中分布于东北平原和内蒙古高原东部,在陕西、宁夏、甘肃等省(自治区)亦有分布,是禾本科牧草中分布最广、利用价值最高的优良禾草。因而分析羊草盖度对产流产沙过程和风蚀过程的影响,明确羊草的水土保持效益,对羊草地的水土流失防治具有重要意义。通过人工降雨试验和风洞试验,研究了5种盖度下羊草地的产沙产流特性和抗风蚀特性,探讨了不同盖度羊草地的水土保持效应。取得了如下主要结论:1.模拟降雨条件下,随羊草盖度的增加初始产流逐渐延后;坡度越大,产流时间越快;雨强越大,产流时间越快。当羊草盖度小于60%时,盖度对产流时间的影响相对较小,羊草盖度为100%时,产流时间最慢。坡度为5°时,产流时间最慢,随着坡度的逐渐增加,产流时间的增加率逐渐增大。黄绵土的初始产流时间快于风沙土的初始产流时间。羊草盖度对不同土类的初始产流时间的影响比较稳定,随着羊草盖度的逐渐增加,风沙土的初始产流时间相比黄绵土的平均滞后速率没有明显变化。2.相同坡度和雨强下,随羊草盖度的增加,累积径流量呈持续减少的趋势。坡度和雨强同样是影响累积径流量的重要因素。盖度为20%时,平均累积径流量76.15 L/(m2·h),当羊草盖度增加到100%时,平均累积径流量减少44%。坡度越大,累积径流量越大,当坡度由5°增加到15°时,平均累积径流量增大26%;雨强越大,累积径流量越大,当雨强由90mm/h增大到120mm/h时平均累积径流量增大42%。风沙土的累积径流量小于黄绵土的累积径流量,随着羊草盖度的逐渐增加,风沙土的累积径流量相比黄绵土的平均减少速率先减小后增大,当羊草盖度为60%时,其减少速率达到最小。3.羊草盖度、坡度和雨强是影响累积产沙量的重要因素,累积产沙量与羊草盖度呈反比,与坡度和雨强呈正比。当羊草盖度由20%增加到100%时,平均累积产沙量减少65%;当坡度由5°增加到15°时,平均累积产沙量增加63%;当雨强由90mm/h增加到120mm/h时,平均累积产沙量增加79%。风沙土的累积产沙量大于黄绵土的累积产沙量,当羊草盖度小于60%时,风沙土累积产沙量相比黄绵土累积产沙量的平均增加速率随着羊草盖度的增加缓慢上升;当羊草盖度为大于60%时,其增加速率迅速增大。4.黄绵土羊草地和风沙土羊草地的产流趋势均呈现在降雨初期产流率快速增长,在降雨中后期产流率保持稳定;产沙趋势呈现在降雨初期产沙率快速增长然后出现小幅回落,在降雨中后期产沙率保持稳定。在降雨过程中的每一个阶段,黄绵土的产流率高于相应条件下风沙土的产流率;黄绵土的产沙率低于相应条件下风沙土的产沙率,在雨强120mm/h、坡度15°和羊草盖度为20%时这一特征表现最明显。5.风蚀量与羊草盖度呈反比,与风速呈正比,黄绵土的风蚀量低于相应条件下风沙土的风蚀量。当羊草盖度从60%增加到80%时,风蚀量的减少率最大,由此可知,羊草抵抗风蚀的临界盖度介于60-80%之间。0-23cm高度内这两层的集沙仪收集到的风蚀物的质量比较接近,主要是由蠕移颗粒和大部分的跃迁颗粒组成,这一高度内收集到的风蚀物占整体风蚀量的70%以上。6.人工羊草地的盖度比较大,从而有效的阻止了风力对土壤的侵蚀。与细竹蒿草相比,羊草的减蚀率达到37.47%。留茬可以有效防止水土流失,与深翻地相比,荞麦留茬的减蚀率是62.01%,玉米留茬的减蚀率是70.99%,羊草留茬的减蚀率与玉米留茬的减蚀率比较接近。
[Abstract]:The vegetation coverage of the Loess Plateau is low, the soil erosion resistance is weak, and the distribution of rainfall is concentrated. The soil erosion is serious, the land resources are destroyed, the soil fertility is reduced and the ecological environment is extremely fragile. The effect of vegetation on soil erosion can not be ignored. The degree of erosion is beneficial to the accumulation of soil in the rainy season. In China, Leymus chinensis is distributed in the Northeast Plain and the eastern Inner Mongolia plateau, in Shaanxi, Ningxia, Gansu and other provinces (autonomous regions), which are the most widely distributed and best used grasses in the grasses. Therefore, the process of runoff and sediment yield and wind erosion are analyzed. The effect of water and soil conservation of Leymus chinensis is of great significance to the prevention and control of soil erosion in sheep and grassland. Through artificial rainfall experiment and wind tunnel test, the characteristics of sediment yield and wind erosion of sheep grassland under 5 kinds of coverage are studied, and the water and soil conservation effect of sheep grassland with different coverage is discussed. The following main conclusions are obtained: 1. simulation With the increase of the coverage of Leymus chinensis, the initial runoff was gradually postponed with the increase of the coverage of Leymus chinensis; the greater the slope, the faster the flow time, the greater the rain intensity, the faster the production time. When the cover of Leymus chinensis was less than 60%, the effect of the coverage on the production time was relatively small. When the cover of Leymus chinensis was 100%, the flow time was the slowest, and the flow time was the slowest and with the gradient of the gradient. The increase rate of the flow time increased gradually. The initial flow time of the yellow soil was faster than the initial flow time of the aeolian soil. The effect of Leymus chinensis coverage on the initial flow time of different soils was more stable. With the gradual increase of the coverage of Leymus chinensis, the initial flow time of the aeolian soil had no obvious change in the average lag rate of the yellow soil. Under the same slope and rain intensity, the cumulative runoff decreased continuously with the increase of the coverage of Leymus chinensis. The gradient and the rain intensity were also the important factors affecting the cumulative runoff. The average cumulative runoff was 76.15 L/ (m2. H) when the coverage was 20%. When the coverage of Leymus chinensis increased to 100%, the average cumulative runoff decreased the greater the 44%. gradient and the cumulative runoff. The larger the gradient increased from 5 to 15 degrees, the average cumulative runoff increased by 26%, the greater the rainfall intensity, the larger the cumulative runoff, the cumulative runoff of the 42%. wind sandy soil when the intensity of the rain increased from 90mm/h to 120mm/h was smaller than the cumulative runoff of the yellow soil, and the cumulative runoff phase of the aeolian sandy soil was gradually increased with the increase of the cover of the sheep and grass. The average reduction rate of the yellowish soil decreased first and then increased. When the coverage of Leymus chinensis was 60%, the decrease rate reached the minimum.3. Leymus chinensis coverage. The slope and rain intensity were the important factors affecting the cumulative sediment yield. The cumulative sediment yield was inversely proportional to the coverage of Leymus chinensis, and was proportional to the slope and rain intensity. The average cumulative sediment yield was increased when the coverage of Leymus chinensis was increased from 20% to 100%. The average cumulative sediment yield increased by 63% when the slope increased from 5 to 15. When the rain intensity increased from 90mm/h to 120mm/h, the cumulative sediment yield increased in 79%. aeolian sandy soil than the cumulative sediment yield of the yellow soil. When the coverage of Leymus Leymus was less than 60%, the cumulative sediment yield of the aeolian soil was compared with the average sediment yield of the yellow soil. The increase rate increased slowly with the increase of the coverage of Leymus chinensis; when the coverage of Leymus chinensis was greater than 60%, the rate of increase in the growth rate of.4. yellow meadow and aeolian sheep grassland increased rapidly in the early period of rainfall, and the rate of yield remained stable in the middle and late period of rainfall, and the trend of sediment yield in the early period of rainfall was faster. At each stage of the rainfall process, the yield of the yellow soil is higher than that of the corresponding wind sand soil, and the yield of the yellow soil is lower than that of the corresponding wind sand soil under the corresponding conditions, in the rainfall intensity 120mm/h, the slope 15 degree and the Leymus chinensis coverage at 20%. The most obvious sign of.5. wind erosion is inversely proportional to the coverage of Leymus chinensis, which is proportional to the wind speed, and the wind erosion of the yellow soil is lower than that of the wind sand soil under the corresponding conditions. When the coverage of Leymus chinensis increases from 60% to 80%, the reduction rate of wind erosion is the largest. Therefore, the critical coverage of Leymus chinensis resistance to wind erosion is between the two layers within the height of 60-80% between the two layers. The quality of the wind erosion objects collected by the sand instrument is close, mainly composed of vermicular particles and most of the transition particles. The wind erosion collected in this height accounts for more than 70% of the total wind erosion of the.6. artificial sheep grassland, which effectively prevents the erosion of the wind to the soil. 37.47%. stubble can effectively prevent soil erosion. Compared with deep ground, the erosion rate of buckwheat stubble is 62.01%, the erosion rate of corn stubble is 70.99%, and the erosion rate of stubble of Leymus chinensis is close to that of corn stubble.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157

【共引文献】