基于3S和~(137)Cs技术的三峡库区小流域泥沙输移比研究

用3S技术对重庆忠县石宝寨的菱角塘小流域进行侵蚀单元的划分,通过137 Cs示踪技术配合GIS空间插值法,评估小流域1963年以来的地面侵蚀量;同时,以137 Cs定年法为主要研究手段,确定塘库不同层位的淤积泥沙的年龄,计算1963年以来小流域塘库泥沙淤积量,从而获得小流域以塘库入口为观测断面的泥沙输移比。研究结果表明:(1)不同土地利用类型的土壤侵蚀量差异明显,从1963-2013年这50年间,小流域侵蚀总量为7 240.5t,林地侵蚀总量为2 095t,坡耕地土壤侵蚀总量为5 145.5t,是林地侵蚀总量的2.45倍;(2)用137 Cs定年法进行计算得出小流域塘库淤积总量为1 927.5t,输出库外的泥沙643t;(3)计算菱角塘小流域1963年以来的泥沙输移比为0.36,小流域的低泥沙输移比说明流域内在坡面下方集中分布的水田以及修建的塘库能够很好拦蓄流域上部坡面的侵蚀产沙。     

基于指纹识别技术的小流域泥沙来源研究进展

泥沙来源判别是小流域土壤侵蚀研究的重点,也是难点。复合指纹识别技术因其结果直接、准确度高、作业快等特点,在国内外泥沙来源研究中得到大量应用,并迅速发展。复合指纹识别技术是在划分潜在侵蚀区的基础上,采集侵蚀区土壤样和流域出口泥沙样,室内分析土壤样和泥沙样指纹因子,利用相关统计检验方法筛选最佳指纹因子组合,利用数值转换模型将最佳指纹因子浓度转换为各侵蚀区产沙比例。主要通过阐述指纹识别技术泥沙来源研究步骤,总结现有可靠性检验方法,归纳研究对象等方面,综述基于复合指纹识别技术的泥沙来源研究进展。重点介绍了复合指纹识别技术最佳指纹因子组合筛选和数值转换模型,并指出复合指纹识别技术存在的问题。     

黄土丘陵区小流域淤地坝纪录的泥沙沉积过程研究

淤地坝是黄土丘陵区小流域水土流失治理的重要工程措施之一,在拦蓄泥沙的同时,也记载了小流域侵蚀产沙的历史变化过程及特征.该研究根据流域历史降雨资料,分析了黄土丘陵区关地沟小流域淤地坝1959～1987年泥沙沉积旋回变化及各旋回层泥沙中、小流域沟间地和沟谷地表层土体中放射性同位素137Cs含量,研究了小流域侵蚀产沙变化过程及泥沙主要来源.结果表明:该小流域在淤地坝建设初期,侵蚀产沙强度很大,其后产沙强度由强变弱,呈显著降低趋势,淤地坝内沉积泥沙的70%来源于沟间地;微小流域与较大流域在泥沙来源方面存在较大差异.     

基于泥沙指纹识别的小流域颗粒态磷来源解析

控制泥沙迁移一直是流域管理的重点,而泥沙携带污染物与养分(磷)对下游水体的影响愈发引起关注。研究泥沙来源的位置、特征及各来源对泥沙输出的贡献,有助于针对重点源区实施水土流失以及水污染治理措施。农业小流域中磷的输出以泥沙吸附的颗粒态磷为主,研究泥沙来源可为探讨颗粒态磷的来源提供重要基础。复合指纹技术是一种可靠的泥沙源解析方法,但在一些地表物质相对均一、输沙量较小、受人为因素影响较多的东部小流域,能否应用指纹识别法解析泥沙来源并探讨颗粒态磷来源还需要验证。该文以南京市九乡河上游小流域为研究区,尝试以指纹识别技术分析流域泥沙来源为基础,进而研究不同来源对颗粒态磷输出的相对贡献。研究结果表明,农田对泥沙输出的贡献为25.3%~65.2%,对颗粒态磷输出的贡献达52.2%~85.8%;矿山及道路施工用地对泥沙输出的贡献为34.8%~74.7%,但是对颗粒态磷输出的贡献仅为14.2%~47.7%;而来源于林地的泥沙与颗粒态磷总体上均不到0.1%。复合指纹技术不但能够有效识别泥沙来源,且以泥沙源解析来研究颗粒态磷来源,能够为基础资料缺乏地区提高颗粒态磷来源识别的合理性以及流域非点源磷污染控制提供一种思路和方法。     

桑干河流域淤地坝沉积泥沙特征及其来源解析

[目的]为查明桑干河流域的泥沙主要策源地和侵蚀产沙变化。[方法]选取阳原县高墙乡典型淤地坝沉积泥沙为研究对象,利用复合指纹识别技术,测定沉积泥沙及其源地的土壤粒径、SOC、TN、¹³⁷Cs、低频质量磁化率等9种指纹因子,研究了不同淤积阶段的泥沙策源地及坝控小流域侵蚀产沙演变规律。[结果](1)沉积泥沙中¹³⁷Cs平均含量较低,与沟壁土壤无显著差异(p>0.05),但极显著小于林草地和耕地的¹³⁷Cs含量(p<0.01),这指示淤地坝沉积泥沙主要来源于沟壁;(2)由于沟壁中大部分¹³⁷Cs含量低于检出限,¹³⁷Cs较好地指示泥沙主要来源沟谷地中的沟壁,但难以用于小流域多种策源地的判别,经Kruskal-Wallis H非参数检验和多元逐步判别分析筛选,确定TN+X_lfb+SOC构成最佳指纹因子组合,有效地判别小流域2006—2017年泥沙源地的平均贡献率为沟壁(82.68%±8.20%)>耕地(15.36%±8.46%)>林草地(1....     

指纹识别技术在泥沙来源研究中的应用进展

指纹识别技术作为一种较新的研究泥沙来源的方法,在泥沙来源研究中获得了越来越多的重视,特别是复合指纹识别技术定量研究泥沙来源在模型和应用方面已取得了一系列进展。本文阐述了传统研究泥沙来源的方法,总结了单因子指纹识别技术以及复合指纹识别技术在泥沙来源研究中的应用原理与进展,并对复合指纹识别技术应用前景及发展趋势进行了分析。     

西南喀斯特小流域地表、地下河流细粒泥沙来源的137Cs和磁化率双指纹示踪研究

在黔中喀斯特高原农林复合生态系统峰丛谷地小流域,利用¹³⁷Cs和磁化率双指纹因子对碳酸盐岩表层土壤(坡地和坝地)、深层土壤(沟道和洞穴/裂隙)以及碎屑岩夹层岩屑3类来源开展指纹特征分析,通过多元混合模型对流域暴雨过程侵蚀悬移质泥沙进行指纹复合示踪,并计算小流域地表及地下出口输出泥沙的主要来源及相对贡献率。结果表明:¹³⁷Cs和磁化率在碳酸盐岩表层土壤、深层土壤以及碎屑岩夹层岩屑3类来源存在显著差异,流域内表层土壤、深层土壤和碎屑岩夹层岩屑的¹³⁷Cs和磁化率平均含量分别为3.39 Bq/kg和310.07×10^-8 m^3/kg、0.50 Bq/kg和180.69×10^-8 m^3/kg、0 Bq/kg和7.02×10^-8 m^3/kg。表层土壤、深层土壤和碎屑岩夹层岩屑对流域地表出口泥沙的相对贡献分别为16.2%,4.3%和79.5%,拟合优度为99.97%;表层土壤、深层土壤和碎屑岩夹层岩屑对流域地下出口泥沙的相对贡献分别为<0.1%,37.9%和62.1%,拟合优度为83.80%。喀斯特流域泥沙来源区别于其他碎屑岩流域具有的特点为:(1)碳酸盐岩风化表层土壤来源少,对河流泥沙贡献小,主要贡献于地表河流。(2)无论流域地表出口还是地下出口,河流泥沙来源主要为流域中碳酸盐岩所夹的少量(地面物质组成<10%)的碎屑岩夹层岩屑。(3)深层土壤略有贡献,地下河流贡献比例高于地表河流。另外,¹³⁷Cs和磁化率可作为双指纹示踪物较好地示踪喀斯特小流域地表、地下河流泥沙来源和确定相对贡献率。     

指纹识别技术在泥沙来源研究中的应用进展

指纹识别技术作为一种较新的研究泥沙来源的方法,在泥沙来源研究中获得了越来越多的重视,特别是复合指纹识别技术定量研究泥沙来源在模型和应用方面已取得了一系列进展。本文阐述了传统研究泥沙来源的方法,总结了单因子指纹识别技术以及复合指纹识别技术在泥沙来源研究中的应用原理与进展,并对复合指纹识别技术应用前景及发展趋势进行了分析。     

基于复合指纹法的九乡河小流域泥沙来源解析

在一个农业和采矿活动较多的小流域,分析了不同用地类型,包括农田、林地、采矿用地等潜在泥沙来源的土壤及泥沙的地球化学性质特征,利用复合指纹和多元混合模型研究了流域输出泥沙的主要来源及相对贡献。研究表明:该方法对不同泥沙来源的正确判别率最高达到87.5%,模型拟合优度达0.93。各泥沙样品中来源于农田的相对贡献为25.3%~65.2%,来源于矿山用地的相对贡献为34.8%~74.7%,来源于林地的泥沙总体上不到0.1%。指纹识别技术在地表物质均一的小流域也能有效识别泥沙的来源。     

基于文献计量学分析泥沙来源研究进展与热点

明确流域或区域泥沙来源对水土保持措施科学布局有重要意义。为了更好地掌握泥沙来源研究的发展动态,研究借助文献计量方法与可视化工具——CiteSpace软件,对中国知网(CNKI)总库和Web of Science数据库迄今关于泥沙来源的所有文献进行收集分析,探寻当前该领域的研究热点,为未来的发展研究提供参考。对检索获取的6 000余篇中文和英文文献的分析发现,当前泥沙来源研究的主要对象包括淤地坝、小流域、河流与盆地。研究热点主题主要包括泥沙输移、泥沙形态和土壤侵蚀; 热点研究内容注重对环境效应、影响因素等进行综合研究; 热点研究手段是复合指纹识别技术。关键词突现图和时区图展现的前沿研究趋势显示,在重点研究区要重建流域泥沙来源历史的演变规律; 指纹识别法作为热点研究手段则亟需科学的试验设计来验证该方法的准确性; 将来的研究则侧重于形成类似“复合指纹系统工具”的工具,服务于流域管理、侵蚀泥沙产生的环境风险预测等方面。     

金沙江干热河谷典型区段水土流失特征

以金沙江干热河谷典型区段不同处理坡面和林地、农地集水区为研究对象,采用坡面径流小区和集水区卡口站三角形薄壁堰实测法,在坡面径流小区和集水区土地利用现状调查基础上,通过降雨、径流及泥沙观测,分析金沙江干热河谷典型区段水土流失特征。结果表明:(1)不同处理坡面径流小区产流量、产沙量大小依次为坡耕地>自然坡面>水平阶整地>反坡台整地,表明反坡台和水平阶造林整地以及植被良好的自然坡面对地表径流的拦蓄和对泥沙的削减都起到较好效果;(2)大暴雨对集水区尺度产流产沙贡献值大,产流降雨量在4.8～27.6mm区间,农地集水区径流深小于林地集水区,大于27.6mm时,农地集水区径流深反超林地集水区,而产沙量不受降雨量影响,为林地集水区低于农地集水区;(3)径流小区尺度与集水区尺度雨季水土流失起止时间一致,集水区径流系数小于径流小区,集水区产沙量大于径流小区。     

Fingerprinting sediment sources in a typical karst catchment of southwest China

Due to the complex hydrogeological conditions in karst regions, it is difficult to measure sediment source contributions at a catchment scale directly. The objective of this study was to quantify the relative contributions of sediment sources and their temporal variability in a karst catchment in southwest China. Karst depressions can trap eroded sediment similar to a dam or reservoir and, thus, are representative and typical test beds for identifying sediment sources in karst regions. Three sediment cores were taken from a karst depression, 58 soil samples from three potential sediment sources were collected, and 18 soil properties were analyzed. The relative contributions of cropland, forestland, and fissure or crack soils were calculated using a multivariate mixing model. The fingerprinting results demonstrated that the cropland was the main sediment source in karst catchment. Specifically, according to the mean sediment contributions of the three deposited sediment cores, the sediment contribution from cropland topsoil was 69.3%, varying from 46.9% to 92.3%, and forestland soil and crack soil accounted for 8.6% and 22.1% of the sediment yield, and varying from 2.8% to 16.5% and 4.8%–36.6%, respectively. This result indicated that great attention should be paid when using only a single core to quantify sediment provenance. Due to the deposited sediment was generally disturbed as cropland in the karst depression, the area that has not been disturbed in recent decades in depression was more appropriate to trace sediment sources in karst catchment. To the best of our knowledge, this study was the first to quantify the contributions of sediment sources in the karst catchment of southwest China. This study provides valuable information and a preliminary reference for applying a composite fingerprinting technique to quantify sediment sources in karst catchments.     

Effect of Land Use,Seasonality, and Hydrometeorological Conditions on the K<Superscript>+</Superscript> Concentration–Discharge Relationship During Different Types of Floods in Carpathian Foothills Catchments (Poland)

The purpose of the study was to determine the role of land use, seasonality, and hydrometeorological conditions on the relationship between stream water potassium (K⁺) concentration and discharge during different types of floods—short- and long-duration rainfall floods as well as snowmelt floods on frozen and thawed soils. The research was conducted in small catchments (agricultural, woodland, mixed-use) in the Carpathian Foothills (Poland). In the woodland catchment, lower K⁺ concentrations were noted for each given specific runoff value for summer rainfall floods versus snowmelt floods (seasonal effect). In the agricultural and mixed-use catchments, the opposite was true due to their greater ability to flush K⁺ out of the soil in the summer. In the stream draining woodland catchment, higher K⁺ concentrations occurred during the rising limb than during the falling limb of the hydrograph (clockwise hysteresis) for all flood types, except for snowmelt floods with the ground not frozen. In the agricultural catchment, clockwise hystereses were produced for short- and long-duration rainfall floods caused by high-intensity, high-volume rainfall, while anticlockwise hystereses were produced for short- and long-duration rainfall floods caused by low-intensity, low-volume rainfall as well as during snowmelt floods with the soil frozen and not frozen. In the mixed-use catchment, the hysteresis direction was also affected by different lag times for water reaching stream channels from areas with different land use. K⁺ hystereses for the woodland catchment were more narrow than those for the agricultural and mixed-use catchments due to a smaller pool of K⁺ in the woodland catchment. In all streams, the widest hystereses were produced for rainfall floods preceded by a long period without rainfall.     

Evaluation of the Effectiveness of Forest Restoration and Check‐Dams to Reduce Catchment Sediment Yield

Reforestations and check‐dams are two commonly used measures to reduce soil erosion rates and sediment export from highly eroding catchments. Here, we evaluated the impact of the construction of 94 check‐dams and land use changes (caused by agricultural abandonment and reforestations) on sediment yield in the Upper Taibilla catchment (320 km², SE Spain) from 1956 to 2000. We combined land use change analysis, field surveys, and application of the WaTEM‐SEDEM erosion and sediment yield prediction model for nine scenarios combining land use maps (1956, 1987, and 2000) and different numbers of check‐dams throughout the catchment. Land use changes alone reduced sediment yield up to 14%, but in combination with check‐dams, the reduction in sediment yield reached 44 ± 6%. Sediment yield reduction was higher in smaller sub‐catchments, with, on average, a higher transport capacity than larger catchments, illustrating the scale dependency of human impacts on sediment fluxes and the buffer capacity of larger catchments. From an economical perspective, the construction of check‐dams was estimated to be more expensive than reforestation programs in the studied catchment, while adding more check‐dams did not always result in a proportional reduction of sediment yield. This indicates that optimizing check‐dam distribution relative to land use patterns is crucial to decrease catchment sediment yield. Check‐dams have a large and instantaneous impact on sediment yield over a restricted time period, while reforestations have important sustained effects at a lower economic cost. These contrasting effects require a careful evaluation for optimal effective catchment management. Copyright © 2014 John Wiley & Sons, Ltd.     

三峡库区小流域修正通用土壤流失方程适用性分析

土壤侵蚀量的定量研究可为国家生态环境建设和水土保持宏观决策的制定提供重要的依据。修正通用土壤流失方程(revised universal soil loss equation,RUSLE)是开展土壤侵蚀定量评价的主要手段。该文在地理信息系统(geographic information system,GIS)的支持下,依据中国土壤流失方程各因子的算法确定RUSLE模型各因子值,估算了三峡库区黄冲子小流域不同时期的土壤侵蚀量,并与基于泥沙平衡原理计算的土壤侵蚀量比较后分析RUSLE模型在库区小流域的适用性。结果表明,基于RUSLE模型估算的小流域1963-2000年(农地小流域)和2001-2014年(林地小流域)的年均土壤侵蚀模数分别为2246.09和868.3 t/(km2·a),其结果与采用137Cs和210Pb技术的塘库沉积物定年结果基本吻合,表明210Pb定年结果可靠。依据泥沙平衡原理计算的小流域1963-2000年和2001-2014年的年均土壤侵蚀模数分别为942.48和811.47t/(km2·a)。RUSLE模型估算小流域1963-2000年和2001-2014年的土壤侵蚀模数相对误差分别为138.32%和7.00%。因此RUSLE模型适用于库区林地小流域,而不适用于库区农地小流域;但是基于地形因子(LS因子)修正的RUSLE模型估算结果相对误差减少至8.14%,其适用于库区农地小流域。     

Relative Contribution of Rill/Interrill and Gully/Channel Erosion to Small Reservoir Siltation in Mediterranean Environments

Reservoir siltation because of water erosion is an important environmental issue in Mediterranean countries where storage of clear surface water is crucial for their economic and agricultural development. The high density of gully systems observed in Mediterranean regions raises the question of their contribution to reservoir siltation. In this context, this study quantified the absolute and relative contributions of rill/interrill and gully/channel erosion in sediment accumulation at the outlet of small Tunisian catchments (0·1–10 km²) during the last 15 years (1995–2010). To this end, a fingerprinting method based on measurements of caesium‐137 and total organic carbon combined with long‐term field monitoring of catchment sediment yield was applied to five catchments in order to cover the diversity of environmental conditions found along the Tunisian Ridge and in the Cape Bon region. Results showed the very large variability of erosion processes among the selected catchments, with rill/interrill erosion contributions to sediment accumulated in outlet reservoirs ranging from 20 to 80%. Overall, rill/interrill erosion was the dominant process controlling reservoir siltation in three catchments whereas gully/channel erosion dominated in the other two catchments. We identified the presence of marly gypsum substrates and the proportion of catchment surface covered by soil management/conservation measures as the main drivers of erosion process variability at the catchment scale. These results provided a sound basis to propose guidelines for erosion mitigation in these Mediterranean environments and suggested to apply models simulating both rill/interrill and gully/channel erosion in catchments of the region. Copyright © 2015 John Wiley & Sons, Ltd.     

1990－2013年东北地区耕地时空变化遥感分析

为揭示1990－2013年东北地区耕地变化规律,以Landsat TM/ETM+/OLI遥感影像为数据源,采用面向对象与目视解译相结合的分类方法,提取东北地区1990年、2000年和2013年耕地信息,辅以气候、地形、社会经济等数据,分析耕地时空变化特征及其驱动因素。结果表明：面向对象分类与目视解译相结合的方法能够快速、准确地完成耕地空间分布信息提取,总体分类精度达93%以上;2013年东北地区现有耕地4.17×105 km2,占东北地区土地总面积的33.51%,其中旱田比例为86.24%;1990－2013年耕地总量增加,2000－2013年比1990－2000年耕地增加速度减小,空间上,耕地呈现南减北增的趋势,新增耕地重心逐渐北移,建设用地侵占耕地速度加快,以省会城市为中心,向东北部蔓延;对湿地、林地、草地开垦减弱,对裸地和海面的农业开发增强,退耕还湿、还草、还林效果明显,耕地变化活跃区处于年降水量在500～700 mm、年均气温在2～4℃、坡度小于3°、高程小于200 m的地理环境中;旱田改为水田规模扩大,旱田质心变化不显著,水田质心向东北移207.41 km。23 a间,虽然气候变化对东北地区耕地变化有一定影响,但政策调控、经济发展、科技进步、人口增长、城市扩张等人文因素仍然是耕地变化和时空分异特征的主要驱动因素。农业发展转型、提高单位面积产量和劳动生产效率,将是未来东北地区耕地发展的必由之路。     

Novel sediment source fingerprinting quantifying erosion-induced total nitrogen and total phosphorus outputs from an intensive agricultural catchment,North China

Intensive farming is a primary cause of increased sediment and associated nitrogen (N) and phosphorus (P) loads in surface water systems. Determining their contributing sources, pathways and loads present major challenges in the high-intensity agricultural catchments. Herein, we quantify the sediment sources and magnitude of sediment total N and total P from different sources using a novel application of compound-specific stable isotope (CSSI) and fallout radionuclides (FRNs) of ¹³⁷Cs and ²¹⁰Pbex in an intensive agricultural catchment in North China. Sediment sources from surface and sub-surface soils were estimated from FRNs fingerprint and accounted for 62 ± 7% and 38 ± 7% respectively, while surface soil from land uses that originated from hillslope were identified by CSSI fingerprint. Using a novel application of FRNs and CSSI sediment fingerprinting techniques, the dominant sediment source was derived from maize farmland (44 ± 0.1%), followed by channel bank (38 ± 7%). The sedimentation rate (13.55 ± 0.30 t ha⁻¹ yr⁻¹) was quantified by the ¹³⁷Cs cores (0–60 cm) at the outlet of this catchment. The total N and total P in sediment were both mostly derived from maize farmland and least from channel banks. The channel banks are significant sediment sources but contribute little to the input of sediment N and P for eutrophication. It implies that chemically-applied farmlands are the main hotspots for catchment erosion control and pollution prevention. The novel application of FRNs and CSSI techniques cost-effectively quantified sediment N and P loads from different sources with a single visit to the catchment, enabling rapid assessment for optimizing soil conservation strategies and land management practices. Keywords: Sediment sources, Land use, N and P loads, Compound-specific stable isotope, Fallout radionuclides.     

Establishing sediment budgets for two small lowland agricultural catchments in the UK

Sediment budgets have been established for two small (<4 km²), lowland, agricultural catchments, by using ¹³⁷Cs measurements, sediment source fingerprinting and more traditional monitoring techniques to quantify the individual components of the budget. The gross and net erosion rates for the fields on the catchment slopes were estimated using ¹³⁷Cs measurements within selected fields, which encompassed a representative range of slope angles, slope lengths and land use. These estimates were extrapolated over the entire catchment, using a simple topographically driven soil erosion model (Terrain-Based GIS, TBGIS) superimposed on a DEM, to derive catchment average gross and net erosion rates. Suspended sediment yields were measured at the catchment outlets and sediment source fingerprinting techniques were used to establish the relative contributions from the catchment surface, subsurface tile drains and eroding channel banks to the sediment yields. In-channel and wetland storage were quantified using both direct measurements and ¹³⁷Cs measurements. The sediment budgets established for the catchments highlighted the importance of subsurface tile drains as a pathway for sediment transfer, accounting for ca. 60% and 30% of the sediment output from the two catchments. Erosion from channel banks contributed ca. 10% and 6% of the sediment output from the two catchments. Although the suspended sediment yields from these catchments were considered high by UK standards (ca. 90 t km⁻² year⁻¹), the sediment delivery ratios ranged between 14% and 27%, indicating that a major proportion of the mobilised sediment was stored within the catchments. In-field and field-to-channel storage were shown to be of similar magnitude, but storage of sediment in the channel system and associated wetlands was relatively small, representing <5% of the annual suspended sediment yield.