A study on responses of soil erosion and sediment yield to closing cultivation on sloping land in a small catchment using 137Cs technique in the Rolling Loess Plateau, China

By comparison of volumes and ¹³⁷Cs contents of the deposited sediments before and after 1993, changes of specific sediment yields and relative sediment contributions from the gully area and from the inter gully area after closing cultivation on the later area on a small catchment of Zhaojia Gully, in the Rolling Loess Plateau, are analyzed in this paper. Closing cultivation in a large scale has not resulted in decrease but increase of specific sediment yield of the catchment, in sharp decrease of the sediment yield and the relative sediment contribution of the inter-gully area, and in increase of the sediment yield and the contribution of the gully area, for a short term. The mean specific sediment yield of 29650 t km⁻² a⁻¹ of 1994–1996 in the catchment was 2.2 times the average value of 13413 t km⁻² a⁻¹ for a long term. The specific sediment yield of the inter-gully area decreased from the 14335 t km⁻² a⁻¹ in 1994 to 7034 t km⁻² a⁻¹ in 1995 and 3517 t km⁻² a⁻¹ in 1996, while the yield of the gully area varied between 44944 and 62136 t km⁻² a⁻¹ during the period of 1994–1996 which was much greater than the value of 21118 t km⁻² a⁻¹ before 1993. The relative sediment contribution from the inter-gully area decreased from 23% in 1994 to 15% in 1995 and 6% in 1996, while the contribution from the gully area increased from 77% in 1994 to 85% in 1995 and 94% in 1996. It is suggested that compacting of ploughed soils resulted in increasing of the erosion resistance but in decreasing of the precipitation infiltration, therefore, the soil erosion reduced but the runoff amount increased on the inter-gully area. Increase of delivering runoff from the inter-gully area to the gully area should result in activeness of gully erosion and mass movements, consequently, in increase of the total sediment yield from the catchment.     

基于淤地坝淤积信息的小流域泥沙来源及产沙强度研究

根据黄土丘陵区王茂沟流域关地沟3号淤地坝29年泥沙沉积旋回变化,以及各旋回层泥沙中、坝控流域沟间地和沟谷地表层土壤中137Cs的测量,结合淤地坝修建、运行历史资料及次降雨资料,估算了坝控流域沟间地和沟谷地的相对产沙量和坝控流域不同时期的侵蚀产沙强度。研究表明,沟间地是该小流域泥沙主要来源,该流域泥沙的70%源自沟间地;坝控流域1959~1987年期间,年侵蚀产沙强度由强变弱,呈显著降低趋势。     

基于RUSLE模型的喀斯特峰丛洼地土壤侵蚀及其养分流失评估

以中国南方典型喀斯特峰丛洼地为研究对象,基于GIS技术和RUSLE模型,对喀斯特峰丛洼地的土壤侵蚀空间变化特征进行了分析。探讨了峰丛洼地土壤侵蚀与土壤养分流失之间的关系,揭示了该地区不同土壤养分流失之间的空间变化差异。结果表明:2015年研究区土壤侵蚀总量为1 950.21×10~4 t·a~(-1),占研究区国土面积的76.75%。土壤侵蚀空间分布整体上呈现出南北两侧向西中部变化的条带状的空间分布特征。因土壤侵蚀引起的土壤有机碳(SOC)、全氮(TN)、全磷(TP)和全钾(TK)等养分流失总量为57.76×10~4 t·a~(-1),其中SOC、TN、TP和TK的平均流失量分别为38.13、1.18、0.16和6.00 t·km~(-2)·a~(-1)。研究区土壤侵蚀的空间变化整体上是随侵蚀等级增加,侵蚀面积和侵蚀量逐渐减少而平均侵蚀模数增加的过程,土壤侵蚀的空间分布差异决定了土壤养分流失空间分布差异。     

Soil Erosion on a Slope without Vegetation： a Simulating Experiment on a Bare Land in Mt. Tanakami

0　IntroductionManystudieshavebeendoneonthesedimentdischargeinMt.Tanakami .Thosestudiesconcerntheamountofsedi mentsandfewdiscussionsabouttheprocessonly .Andthesedi mentyieldmechanismindevastatedslopeinMt.Tanakamiisnotfullyunderstood.Inordertorecordthewholeprocessofsoilero sionfromthebeginningofprecipitation ,totheendofsedimentmovement,asimulatingexperimentbyusingartificialrainiscon ducted .Basedonthisexperiment,andbyfurthercomparingwiththepreviousdataofsedimentsinthisarea,somebasicdataaboutc…     

Identification of the deposited layers in landslides reservoir and investigation of the sediment yields during the later sixteenth century on the Hill Loess Plateau,China

There are many sediment trapping reservoirs in the Hill Loess Plateau. The Huangtuwa small catchment is selected as a research field where samples were collected in a sediment deposit profile with a vertical length of 12.73 m. By the variation of fine particle content and pollen concentration, 54 flood couples were identified. Taking the freeze-thawing disturbed texture as the sign of the latest flood couple in a year, it is ascertained that those 54 floods should happen in 31 years. Using pyramid volume calculation formula, the sediment yields of flood ranged between 716-30376 t· km^-2, The average sediment yield was 7106 t· km^-2, The annual sediment yields varied between 968-55579 t· （km^2· a）^-1, and the average value is 12629 t· （km^2· a）^-1. Compared with the modern annual sediment discharge of the Huaining River, the erosion rate in the Huangtuwa region 450 years ago was similar to the modern erosion rate. In the period from the 27th year to the 31st year, the average annual sediment yield increased sharply to 31309 t· （km^2· a）^-1. It implied that re-reclamation of the abandoned land in the catchment since the landslide disaster, where vegetation had rehabilitated already, caused very severe soil erosion in the catchment.     

典型铁路工程边坡降雨侵蚀过程规律调查

在我国水力侵蚀5大分区选取典型铁路边坡进行径流小区侵蚀或沟蚀侵蚀试验,通过试验数据结果分析各个典型铁路工程边坡的水力侵蚀过程和主要影响因素,给出了铁路工程边坡水力侵蚀入渗过程、产流过程、产沙过程和侵蚀模数的时间过程规律,以及各过程主要因素的影响规律.     

Impacts of Soil.Water Conservation in Jialing River on Sedimentation of the Three Gorges Reservoir

The Jialing River is one of the main tributaries of the Yangtze River. The average annual runoff accounts for 16 % and the sediment load 26% of the total at Yichang therefore it＇s one of the main contributors of sediment to the Three Gorges Reservoir. Ever since 1989, our country has implemented ＂Yangtze River soil and water conservation＂ project, Till the end of 1996, altogether 25.8 % of erosion area in Jialing River has been improved after large scale conservation has taken effect. The analysis and comparison between records taken before and after the implementation of soil and water conservation on runoff and sediment yield indicated that the sediment load soil erosion in Jialing river basin has been taken under control to some extent. Amount of annual runoff in main conservations have generally dropped by exponential function. Obvious result has been achieved in Jialing River, efficiency of sand reduction is about 10%-25%. Therefore, sediment to Three Gorges Reservoir is decreased accordingly, and it will be beneficial to take advantage of reser- voir＇s synthetic benefit.     

无人机摄影测量提取黄土高原切沟参数精度分析

选取陕北黄土丘陵沟壑区桥沟小流域为研究区,分别用同时相的地面三维激光扫描数据和固定翼无人机摄影测量数据提取切沟形态参数,分析无人机摄影测量提取切沟参数的误差及其原因．结果表明:1）无人机摄影测量与三维激光测量比较,提取切沟面积、周长和沟长二维形态参数的百分误差<10%;2）与三维激光扫描测得切沟横截面积、平均沟深和体积三维形态参数相比较,无人机摄影测量误差<20%,沟壁陡峭、植被覆盖度较高的大型切沟测量参数误差较大,而沟壁坡度相对较小、植被相对稀疏的小型切沟测量参数误差较小;3）固定翼无人机垂直摄影采集数据的方式会导致切沟沟壁细节数据缺失,从而降低切沟参数提取精度．基于无人机摄影测量生成的DSM无法有效过滤植被影响,在一定程度上影响切沟参数的提取精度．与三维激光测量相比,无人机摄影测量切沟地貌参数的精度略低,在切沟短期动态变化监测方面还存在一定的局限性．      

Changes in overland flow and sediment during simulated rainfall events on cropland in hilly areas of the Sichuan Basin, China

Water and soil loss are the major causes of the land degradation in the hilly area of the Sichuan Basin, China, where purple soil (FAO, Calcaric Regosols) is widely distributed. Little research has been conducted on changes in overland flow and sediment during rain events on sloping cropland in this area. In this study, 45 artificial rainfall events were applied to five runoff plots with slopes of 9%, 18%, 27%, 36%, and 47%, respectively. Results showed that erosion processes on purple soil of sloping cropland are complex, because the sediment concentration changes with time under different situations. According to correlations between runoff discharge and sediment concentration, all erosion events were classified into three types: (1) positive correlation; (2) negative correlation; and (3) no correlation. Positive correlations were dominant, accounting for 60% of all events. Rainfall intensity, slope gradient, and tillage treatment were the main factors that influenced erosion events.     

黄土地区小流域次暴雨侵蚀产沙研究

通过坡面模拟降雨实验，分析了黄土地区坡面降雨径流产沙过程的主要影响因素，建立了坡面径流含沙量与坡面流量、前期土壤含水量、土壤干容重之间的定量关系。应用实测资料分析了黄土地区暴雨径流侵蚀产沙特点，建立了考虑流域前期土壤含水量和径流涨落段的含沙量与流量之间的水沙传递关系，建立了小流域次暴雨侵蚀产沙模型。经用实测资料计算检验，此模型对小流域次暴雨侵蚀产沙过程及产沙总量的计算结果都具有较高的精度。     

流域泥沙过程机理分析

黄土高原地质地貌复杂，是黄河流域的主要泥沙源区，并以黄土丘陵沟壑区和黄土高塬沟壑区为代表．沟壑区的不同部位具有不同的侵蚀产沙现象，并在不同的空间尺度上表现出迥异的水沙运动规律．为此需将流域分为坡面与沟道两大系统分别研究，本文描述坡面侵蚀产沙、沟坡区重力侵蚀和沟道水沙运动的主要现象，分析各水沙过程的主要机理．揭示出可依据坡面径流建立坡面侵蚀产沙模型；根据水流的诱发作用，用沟坡土体失稳的随机力学模型模拟沟坡重力侵蚀；考虑影响水沙运动的多种要素，建立沟道系统的高含沙水沙模型．流域泥沙过程机理的研究为建立符合实际物理图景的水沙模型系统，完成流域泥沙过程模拟提供基础。     

Preliminary results of the study on wind erosion in the Qinghai-Tibetan Plateau using 137Cs technique

The worldwide fallout of caesium-137 (137Cs) associated with the nuclear weapon tests during the 1950s and 1960s has provided a valuable man-made tracer for studies of soil erosion and sediment delivery. But relatively few researchers have used it to estimate wind erosion. In this note, the 137Cs technique is introduced into the studies of wind erosion and its modern processes in the Qinghai-Tibetan Plateau. Two 137Cs reference inventories of 982.11 and 2 376.04 Bq·m-2 were established preminarily, distributed in the south and middle-north parts of the studied area respectively. By analyzing the patterns of 137Cs depth profiles from sampling sites, the aeolian processes of erosion and deposition in nearly 40 years have been revealed, i.e. the shrub coppice dunes (S1) and semi-fixed dunefields (S3) experienced the alternation of erosion and deposition, while the grasslands (S4, S6 and S7) and dry farmlands (S5) suffered erosion only. By using 137Cs model, the average wind erosion rates for shrub coppice dune (S1), semi-fixed dune fields (S3), dry farmlands (S5) and grasslands (S4, S6 and S7) were estimated to be 84.14, 69.43, 30.68 and 21.84 t·ha-1·a-1 respectively, averaging 47.59 t·ha-1·a-1 for the whole plateau, which can be regarded as of the medium erosion standard. These results derived from 137Cs for the first time have significant implications for the further research of wind erosion and desertification control in the Qinghai-Tibetan Plateau.     

三峡库区紫色土坡耕地土壤侵蚀研究：进展与方向

紫色土坡耕地是三峡库区粮食经济作物的主产载体,也是库区水土流失的主要源地和入库泥沙的主要来源。结合野外调查和相关报道,对三峡库区紫色土坡耕地土壤侵蚀研究方法、侵蚀强度、泥沙颗粒形态以及侵蚀引起的养分流失等方面进行综述。结果表明,坡耕地土壤侵蚀研究方法主要包括径流小区法、人工模拟降雨法和侵蚀针法等直接观测方法和核素示踪、模型模拟和遥感监测等间接观测方法;库区紫色土坡耕地土壤侵蚀速率达3464～9452t／km2,其中15°～25°坡度范围的土壤侵蚀最为严重,是今后坡耕地土壤流失防治的重点坡段;流失泥沙主要以〈0．02mm的团聚体和〈0．002mm的粘粒为主,其中粉粒（0．002~0．02mm）和粘粒（〈0．002mm）携带的养分流失较多;植物篱、垄作和坡改梯等措施理水效果明显,均对坡耕地侵蚀产沙具有较好的控制作用。今后应在模型方法、埂坎结构和功能、水土保持措施适宜性评价等方面拓展研究。     

岔巴沟流域次降雨水沙耦合关系空间变异研究

在全面分析岔巴沟流域地貌形态、沟网及降雨空间分布等因素基础上,结合野外实地观测资料,对该流域次降雨水沙耦合关系及其空间变异性进行了研究.结果表明,岔巴沟流域次降雨输沙模数与洪峰流量模数及径流深具有较强的相关性,这种相关性耦合关系具有明显的空间变异性,流域面积、地貌形态等下垫面因子是形成该空间变异性的主要原因.     

黄河中游小流域产沙机理与治理对策

选取黄河中游河段上的支流：皇甫川、窟野河、无定河上一些小流域作为典型流域进行分析研究，根据下垫面差异，将产沙区分为黄土区、基岩区、风沙区、通过各产沙因子对侵蚀产沙影响作用的分析，对三种产沙区进行定性到定量分析，全面研究了黄河中游产沙机理，并进一步提出了治理对策，本文研究的典型流域指基本上具有单一下垫面物质组成的流域。     

Sediment source identification by using ^137Cs and ^210pb radionuclides in a small catchment of the Hilly Sichuan Basin, China

The Hilly Sichuan Basin is one of the most populous agricultural regions in the Upper Yangtze River Basin and has an area of about 105000 km2. Cropland ratios and population densities vary between 0.3 and 0.7 and be-tween 400 and 800 people/km2, respectively, in the Si-chuan basin. The basin is considered as one of the most severely eroded regions in the Upper Yangtze River Basin as well in China. Soil erosion rates were reported mostly to be greater than 5000 t·km-2·a-1 by the first st…     

集水区径流资源空间变化的模拟与分析

利用高泉沟流域１９８８－１９９５年８年３１个观测小区定位观测的６３次流资料,模拟出了基于ＧＩＳ栅格系统的小区降雨－产综合模型;采用ＡＲＣ／ＩＮＦＯ系统,建立了研究区栅格ＤＭＥ、多年平均降水因子等空间数据库;提出了一种新的基于ＧＩＳ栅格系统的计算集水区总产流量的反演算法,模拟同泉沟流域径流资源的时空变异规律。     

典型强降雨下不同植被类型水土保持特征分析

设置地表径流观测场,观测强降雨下不同植被恢复5年后产流、产沙特征.试验结果表明,苦竹＋牛鞭草植被类型在此次强降雨为106.3mm情况下,产流、产沙量占其全年的15.24%和17.072%,调节降雨和抑制土壤侵蚀的能力最强;农耕地产流、产沙量占其全年的22.05%和31.65%,其中产沙量达其他3种植被类型的4.6-13.3倍,水土保持能力最弱;桦木＋牛鞭草、杂交竹＋牛鞭草植被类型因桦木生长和杂交竹间歇性采伐的原因,水土保持能力居于中等水平;对比农耕地来说,3种植被类型恢复后土壤侵蚀得到了有效控制,但强降雨下地表径流控制程度还较弱,需继续加强对土壤—植被系统的培育.     

基于一二维耦合内涝模型的城市道路积水来源量化分析

为模拟道路地表径流和排水系统溢流对道路积水的影响, 对道路汇水区采用地表二维模型, 对其他汇水区和地下管网采用一维模型, 并构建基于PCSWMM的一二维耦合内涝模型, 提出以本地道路地表径流和检查井溢流对积水贡献比例为指标的积水来源定量分析方法。基于实测检查井液位数据和积水深度数据对模型进行验证后, 利用该模型对设计暴雨条件下深圳市南山区某排水片区的道路积水进行模拟, 得到如下结果。1) 研究区存在4个主要道路积水点(A, B, C和D), 在重现期为5年的暴雨下, 有两个积水点(A和D)发生溢流, 溢流在积水中的占比分别为24%和61%; 在重现期为50年的暴雨下, 有3个积水点(A, C 和D)发生溢流, 溢流在积水中的占比分别为49%, 62%和73%。随着暴雨强度增大, 检查井溢流对积水的贡献增加。2) 道路积水的动态变化受到积水来源、下游壅堵和局部地形等诸多因素的综合影响。3) 对于溢流在积水中占比较大的内涝点, 建议着重提高管网排水能力, 并对上游汇水进行海绵化改造; 对于本地道路径流在积水中占比较大的内涝点, 建议对本地进行海绵化改造, 适当地改造局部地形, 或增加排涝泵站等设施。     

Prediction of Soil Erosion on Different Underlaying Surface in Construction Period of Xichang to Panzhihua Expressway

In order to investigate the behavior of soil erosion on the slope of the different underlaying surface during construction, the experiment with natural rainfall on Xichang-Panzhihua highway was conducted, to quantify the runoff and soil loss. The results show that. （1） the main type of soil erosion is gully erosion, the amount of soil erosion caused by gully erosion is higher than that by surface erosion. （2） The principal factor causing soil erosion on the slope of the embankment is individual amount of precipitation, the width of the embankment and rain intensity. （3） The principal factor causing soil erosion on the cutting slope is individual amount of precipitation, the width of the cutting slope and rain intensity. （4） The principal factor causing soil erosion on the slope of the dumped soil area is individual amount of precipitation, the width of the flat roof and rain intensity. There are well linear relationships between the amount of soil erosion and the principal factor, and their correlation coefficient are 0.935 7-0.999 8.