【作者】 郑海金；

【导师】 张洪江；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2012， 博士

【摘要】 坡面水土流失一直是国内外的研究重点和热点,目前国内对于其调控机制等进行了很多的研究工作,但现有研究成果多集中于黄土地区,其它水蚀地区(如南方红壤区)该力一面的研究成果还不多。本研究在典型南方红壤区——江西水土保持生态科技园设置16个径流小区,对2001～2009年次降雨条件下的降雨、地表径流、侵蚀泥沙进行了长期定位观测和土壤理化性质测定,以探讨典型红壤坡面水蚀特征,系统研究几种水土保持措施(林草覆盖、农林间作、清耕和林果梯田等措施)对红壤坡面减流减沙、理水调洪和土壤抗侵蚀性的影响及作用,为红壤坡面水土流失防治提供技术支撑。主要研究成果如下：(1)在南方红壤区,受降雨年内分配的影响,裸露坡面汛期(4-9月)径流深占年均径流深的86.3%,汛期泥沙流失量占年均泥沙流失量的96.5%,汛期是防治水土流失的重点时段。受天然降雨强度非均匀性的影响,实际产流产沙过程是不稳定和不连续的,呈现出一峰或多峰的特性；同一场降雨裸露坡面产流、产沙过程基本一致,累积产沙量和累积径流量随时间延长呈现出先小幅增长后快速增加最后趋于平稳的变化。同降雨强度相比,降雨量的变化对裸露坡面径流量的影响更为显著,这与当地以蓄满产流为主有关。与平均雨强相比,I30能更好地反映降雨强度与土壤流失量的关系。裸露坡面径流量与降雨量、降雨动能呈直线回归关系,与I30为幂函数回归关系；侵蚀泥沙量与降雨量、降雨动能、I30和径流损失量均呈幂函数回归关系。(2)在南方红壤区,所研究的几种水土保持措施均能有效降低地表径流量,减少土壤侵蚀量。其中：林草覆盖措施的年均减流率在90%以上、年均减沙率在99%以上,农林间作措施的年均减流率在65%以上、减沙率在75%以上,柑橘清耕的年均减流率在33%以上、年均减沙率在58%以上,林果梯田措施的年均减流率在70%以上、年均减沙率在89%以上。在林草覆盖措施中,全园覆盖、带状覆盖、带状覆盖+间作作物的减水效益都在95%以上、减沙效益都在99%以上,差别不大,因此考虑降低成本,避免物种竞争,采取等高水平草带(作物)措施更优；百喜草=、阔叶雀稗、狗牙根三种牧草的减水减沙效益都很好,且无明显差别,因此这三种草均可推广于条带种草。在农林间作措施中,横坡农林间作的累积减流减沙效应优于顺坡农林间作,且在大暴雨、特大暴雨的特殊情况下优势表现得史为突出。因此,横坡套种作物增加覆盖可作为防治坡耕地水土流失的有效措施。但由于每年的4～9月是研究区水土流失较严重季节,故应注意选择那些收获和栽种时间不在强降雨多发期的作物。柑橘清耕在某些特殊情况下,其减流减沙效应大大降低甚至出现减流减沙效果还不如裸露对照的现象,这也很好地解释了我国南方林下水土流失的现象。在林果梯田措施中,前埂后沟技术、梯壁植草技术和梯面内斜技术的减流减沙优势明显,在特大暴雨的特殊情况下表现得更为突出。因此,可集成这三项单项技术,增强对暴雨侵蚀的抵抗力。(3)在南方红壤区,通过几种水土保持措施(柑橘+百喜草全园覆盖、柑橘+作物(横坡间作)、柑橘清耕、柑橘+水平梯田(梯壁植草))的滞流削峰效应分析,发现与裸露对照相比,这些水土保持措施具有一定的削减地表径流洪峰和减少地表径流总量的效益,其中以柑橘+百喜草全园覆盖最优,其削峰效益均值为93.7%、减流效益均值为99.1%；柑橘清耕最差,其削峰效i益均值为53.8%、减流效益均值为49.8%；柑橘+作物(横坡间作)和柑橘+水平梯田(梯壁植草)居二者之间。除柑橘清耕外,其余3种水土保持措施还具有一定的产流滞后和峰值滞后效益,其中以以柑橘+百喜草全全园覆盖最优,其产流滞后效益均值为93.3%、洪峰滞后效益均值为57.5%。柑橘清耕因幼龄林下无灌草覆盖,其产流对降雨较为敏感,产流与峰现滞后时间要短得多,甚至出现产流滞后、峰值滞后效应不如裸露对照的现象。同一种水土保持的削峰减流效应较稳定,变幅不大；但产流与峰现滞后效应变化幅度较大,这与径流滞后效应受当场降雨、前期降雨和下垫面等多因素影响有关。(4)赣北红壤荒坡地土壤抗蚀性差,不同水土保持措施治理后土壤抗蚀性有所提高。灰色关联法计算结果表明：土壤最佳抗蚀性指标依次为团聚度和受蚀性指数(Eva)；土壤最差抗蚀性指标分别是湿筛水稳性团聚体平均重量直径(EMWD)和干湿筛团聚体平均重量直径差值(MWDC);土壤颗粒分散特性对土壤侵蚀量影响较大,而土壤稳定性参数对土壤侵蚀量影响较小,它们的均关联度依次为0.618和0.599。以田间实测K值为依据,对多种K值估算方法(诺谟图法、修正诺谟图法、EPIC模型法、平均几何粒径模型法和Torri模型法)进行了评价,发观这些估算方法的不确定性都较大,具体应用时需进行优化。建立了试验区修正诺谟图法的优化模型。更多还原

【Abstract】 The research of water erosion on slopes has been priorities and hotspots at home and abroad. So far, lots of research work was carried on its regulation mechanism. While, most of the research results in China are about the water erosion in the Loess Area, and the targeted outcomes of other areas, such as the Southern Red Soil Area, are still relatively limited. To study the mechanism of different soil and water conservation measures affecting water erosion in red soil slopes in southern China, field experiments were performed on the representative area named Jiangxi Eco-science Park of Soil and Water Conservation(SWC), including sixteen runoff plots treated by different measures,i. e. forest and grass measures, agricultural cultivation measures, clean tillage in orchard, fruit terraced measures and bare control. The precipitation, surface runoff and soil loss of each treatment under each natural rainfall events were recorded from 2001-2009 and the physical soil properties and chemical soil properties were tested after 9 years. This research explores the effects of SWC measures on runoff and sediment yield, water and flood regulation and soil anti-erodibility in red soil sloping land which can provide a scientific refference for the optimization of SWC measures and sustainable development of ecological environment construction. The main results are as follows:(1) The rain process mostly happened in the rainy season(from April to September), so the runoff amount from the bare slope in the rainy season accounted for 86.3% of the average annual runoff loss, and the sediment yield from the bare slope in the rainy season accounted for 96.5% of the average annual soil loss. Thus, the rainy season is the key period to control and prevent soil and water loss. Under the conditions of national rainfall, the rainfall intensity was not stable and continuous, so the runoff process of the bare slope was also unstable and uncontinuous, with one or more peak values. The process of runoff and sediment under the same rainfall condition was the same in barren slope. The cumulative sediment yield and the cumulative runoff with time showed a slight growth at the first, then a rapid growth and a smooth change finally. Due to runoff yield under saturated storage, the relation of runoff with rainfall was higher than that with rainfall intensity. There existed linear regression between runoff and rainfall, rainfall energy, while there was power function regression between runoff and I30-Comparing to average rainfall intensity,Ⅰ-30 can better reflect the relation between soil erosion and rainfall intensity. There existed power function regressions between runoff andⅠ30, rainfall, rainfall energy and runoff amount.(2) These SWC measures can effectively reduce the amount of soil and water loss. Comparing to the control plot, the runoff of forest and grass measures (Citrus+grass) were reduced by more than 90% and the sediment were reduced by more than 99%. The runoff of agricultural cultivation measures were reduced by more than 65% and the sediment were reduced by more than 75%. The runoff reduction rates of clean tillage in orchard were above 33%, and its sediment reduction rates were above 58%. The runoff reduction rates of fruit terraced measures (Citrus+terrace) were above 70%, and their sediment reduction rates were above 89%. Among the Citrus+grass treatments, the benefits of water reduction was above 95% among grass full covered, grass stip covered and grass+crops stip covered, while their benefits of soil reduction rates were above 99%. Therefore, to reduce the cost and avoid species competition, grass or crops strip covered in orchard are suggested. Among the three species of Bahia grass, Broadleaf paspalum and Cynodon dactylon, their reduction benefits of runoff and sediment had no obvious difference. Therefore, the three grasses can all be applied to orchard with grass strip covered. Among strip intercropping in Citrus orchards, the cumulative SWC benefits of contour strip intercropping was better than that of downslope strip intercropping, and the former’s SWC benefits were more outstanding under the special case of stroms. Therefore, contour strip intercropping to increase the coverage rate in new orchards is an effective measure to prevent soil erosion. As it is known, soil and water loss concentrated in the rainy season in this area. When planting intercropping crops, we should try to choose those their harvest and planting time aren’t in the rainy season. On some special cases, the runoff and sediment reduction effects of clean tillage in Citrus orchard were significantly decreased even had more soil and water loss than that of the bare control. This can well explain that only tree layer without the coverage of litter, shrub or grass, is easy to cause the forest soil erosion phenomenon in South China. Among Citrus+terrace measures, SWC benefits of mound before and ditch behind on terrace platform, grass planting on the terrace wall, and inward inclined terrace were well, especially in the special case of storms. Thus, integrating these three individual technologies will obtain better SWC benefits, to enhance the erosion resistance of orchards to storms.(3) Reducing effects and lagging effects of runoff and its peak of several typical SWC measures, i.e. Citrus+Bahia grass full covered, Citrus+contour strip intercropping, clean tillage in Citrus orchard, Citrus+level terrace with mound before and ditch behind+grassed wall were analyzed. It was found that compared with the bare control, all these SWC measures had obvious benefits to reducing surface runoff amount and its peak values. Citrus+Bahia grass full covered had the greatest benefits, with 93.7% of runoff amount reduction rate and 99.1% of runoff peak reduction rate. While, clean tillage in Citrus orchard had the lowest benefits, with 53.8% of runoff amount reduction rate and 49.8% of runoff peak reduction rate. In addition to clean tillage in Citrus orchard, these three measures also have certain benefits to lagging runoff and its peak. Citrus+ Bahia grass full covered had the greatest benefits, with 93.3% of runoff lagging rate and 57.5% of runoff peak lagging rate. Clean tillage in young Citrus orchard hasn’t the coverage of litter, shrub or grass, runoff is more sensitive to rainfall. So, its lagging time of runoff and its peaks were significantly shortened, even shorter than that of the bare control. Tor the same SWC measure, the benefit to reducing surface runoff amount and its peak valus was relatively stable. While, the benefit to lagging runoff and its peak was more unstabcle, mainly due to its multi-factors of rainfall (including early rainfall) and surface conditions.(4) Red-soil anti-erodibility was poor on barren slope in North of Jiangxi. Different SWC measures were applied to improve soil anti-erodibility. By grey correlation analysis of different anti-erodibility parameters on soil erosion modulus, it was shown that in the 10 anti-erodibility parameters, the first 2 factors affecting soil erosion modulus was soil agglomeration and soil erodibility index. The descending rank of the last 2 factors affecting sediment yield was EMWd and MWDC. The effects of soil particle dispersivity on sediment yield was better than that of stability of soil water-stable aggregates, their average grey correlation value were 0.618 and 0.599, respectively. Based on observed K factors of red soil in the study area, uncertainties of six K-factor prediction models(i-e-, nomogragh model, modified nomogragh model, EPIC model, two kind of geometricmean particlemodel, and Torri model) were evaluated. Results show that the six models were all high in uncertainty. Immeasurable error might result from direct indiscriminate use of these empirical models in estimating K factor. So, an optmized modified nomogragh model can minmize the uncertainty.更多还原