美国大流域长时间序列水土保持减沙效果分析

 为借鉴美国开发治理比较早的一些河流的经验教训,选择密苏里河上游的Willow、佐治亚州LloydShoals水库、韦科、田纳西河一级支流渡科河、科罗拉多河上游等5条较大的流域进行水土保持减沙效果分析。通过前后长达1032年的大流域、长时间序列的水土流失治理,在排除降雨和水利工程影响的因素,其下游河道减沙效果都很显著,减沙分别在38%～55%之间。     

紫色土区小流域侵蚀产沙对水土保持措施的响应

探讨降雨量与水土保持措施对流域水沙关系的影响,对流域水土流失预报和水土保持效益评价具有十分重要的科学意义,但在紫色土区这方面的研究还相当薄弱。以鹤鸣观小流域Ⅱ号支沟实测降雨径流泥沙数据为基础,分析了水土保持措施对流域径流、泥沙及水沙关系的影响。结果表明:流域治理后期,降雨产流量变化率、降雨产沙量变化率均减小,随着降雨的增多,水土保持措施对径流、产沙的影响效应增强;暴雨强度愈小,降雨量愈少,水土保持径流拦蓄作用愈显著;但降雨量愈大,泥沙拦蓄作用愈显著;流域减水量一般在30%~70%,而减沙量都高于90%,减沙量明显高于减水量;由于水土保持综合治理的作用,1989年后的多年平均径流量较1989年前减少33.11%,多年平均产沙量减少90.50%。     

A decision support system for soil and water conservation measures on agricultural watersheds

Integrated watershed management (IWM) is vital in achieving agricultural sustainability in terms of both production and environmental protection. A decision support system (DSS) is useful in generating alternative decision scenarios for management of natural resources, facilitating the implementation of IWM concepts in an interactive and holistic way. The decision to implement an appropriate land use coupled with suitable soil and water conservation techniques not only enhances watershed health but also prevents sediment losses. Besides reducing basin fertility, such losses decrease the storage capacity of downstream reservoirs through silt deposition, which can, in turn, give rise to low biomass production and poorer flood control. In order to facilitate IWM, an effort was made to develop, in the Visual Basic programming language, a soil and water conservation DSS which considered both structural and cropping practices for arresting sediment loss. Input parameters to the DSS for a given tract of land included: mean slope; sediment loss; soil type; and land capability class (LCC). Outputs included decision criteria to choose among alternative structural measures and suggested cropping systems to serve as biological measures to reduce soil loss and conserve water. Structural watershed management measures included a variety of soil and water conservation structures widely adopted by farming communities throughout the world. The DSS is capable of providing sediment control solutions not only for small watersheds but also for larger drainage basins, by dividing the basin into smaller watersheds. The DSS was validated for a watershed on the Caribbean island of St Lucia and used to suggest measures for a 10° slope under specific soil type, sediment loss and LCC conditions. The measures proposed included bench terraces, graded contour bunds, conservation ditches, concrete chute spillways, diversion dams and conservation cropping systems. The measures actually adopted on‐site were conservation ditches, graded contour bunds and conservation cropping systems, a close parallel to the DSS's proposed measures. On slopes ranging from 5–55°, implementation of the suggested control measures resulted in a 34–37 per cent reduction in soil loss on the watershed. Copyright © 2004 John Wiley & Sons, Ltd.     

Assessing the potential of changing land use for reducing soil erosion and sediment yield of catchments: a case study in the highlands of northern Ethiopia

Reservoir sedimentation is the most serious threat for water harvesting schemes and hydroelectric power dams in Ethiopia. Designing watershed conservation strategies and management is crucial to reduce the rate of sedimentation. Because different landscape types have varying potentials for enhancing erosion processes, site‐ and process‐specific conservation measures are needed to target an appropriate intervention to the most needed locations. In this study, a GIS‐based distributed soil erosion/deposition model was used to simulate the potential of land‐use and cover (LUC) changes and conservation measures for reducing water induced soil erosion and potential sediment yield for two catchments in northern Ethiopia. LUC change and conservation measures targeted gully and stream buffers, protection of steep slopes and protection of areas with soil loss greater than a given threshold. The results show that land management measures targeted at hot‐spot areas of erosion and gully formation could reduce potential annual sediment yield from catchments by approximately 60% compared with the current losses. The study demonstrates the potential of a GIS‐based LUC‐redesign approach as a tool for optimizing land‐use and management strategies to reduce run‐off and erosion rates in the highlands of northern Ethiopia.     

降水和土地利用变化对罗玉沟流域水沙关系的影响

为探讨降水和土地利用变化对流域水沙关系的影响,以黄土高原丘陵沟壑区罗玉沟流域为研究区域,利用流域25年(1986—2010年)的年降水量、年径流量和年输沙量以及土地利用变化资料,分析罗玉沟流域水沙演变规律和水沙关系变化。结果表明:在1986—2010年罗玉沟流域年降水量和汛期降水量基本保持平稳,无明显的增减趋势,而流域年径流量和年输沙量整体呈波动递减的变化趋势,降水与径流相关分析得出,汛期产流产沙对流域年径流量和年输沙量影响最显著。对不同时期流域水沙变化分析,土地利用方式改变,主要是梯田、林草等水土保持措施,对于流域减水减沙作用有限,梯田和林草面积的增加并未明显改变流域水沙关系,淤地坝等工程措施对黄土高原丘陵沟壑区流域减水减沙具有重要作用。研究结果可为黄土丘陵沟壑区水土流失治理及水土保持措施布设提供理论依据。     

Quantitative analysis of morphometry on Ribb and Gumara watersheds: Implications for soil and water conservation

Morphometric analysis is a quantitative measurement and mathematical analysis of landforms. It plays a significant role in understanding the geohydrological characteristics of a drainage basin in relation to the terrain feature and its flow patterns. It also helps to estimate the incidence of infiltration and runoff, and other related hydrological character of a watershed like erosion and sediment transport which has a strong implication for natural resource conservation. This study has attempted to quantify the morphometric characteristics of Guna- Tana watershed for proper implementation of soil and water conservation practices. ASTER (DEM) was used for extracting morphometric parameters. The watershed covers a total area of 3601.5 km² and it has a basin length of 78.89 km. It has been tried to generate morphometric parameters which account basin drainage network, geometry, drainage texture, and relief characteristics together with hypsometric characteristics. The morphometric analysis of drainage density of the study watershed is 0.49 km/km² which indicates the basin is highly permeable and result with better underground water storage capacity. Ruggedness number is 0.02 that implies the area is less prone to soil erosion. In addition, it has stream frequency of 0.32 and form factor 0.57 which indicates slightly elongated basin shape. Comparative analysis of its sub watersheds Gumara and Ribb was also undertaken. Therefore, practicing soil and water conservation in the watershed could enhance/strengthen the water storage capacity, prevent sediment loss and related natural resource from the watershed that rehabilitate its productivity.     

黄土丘陵沟壑区不同土地利用方式下小流域侵蚀产沙特征

为进一步优化和合理配置水土保持措施,以黄土丘陵沟壑区3个不同土地利用方式下的坝控小流域为例,基于人工探槽取样、淤积层次甄别及与产流降雨事件的对应关系,结合1∶10 000早期地形图与全站仪测量,拟合库容曲线来估算淤地坝泥沙淤积量,进而反演坝控流域的产沙模数变化特征。结果表明:(1)延河马家沟3个不同土地利用方式下的洞儿沟、阎桥和芦渠坝控小流域,自建坝至2016年的多年平均淤积量分别为2 748.80,4 634.31,3 141.17 t;(2)洞儿沟、阎桥和芦渠流域多年平均产沙模数分别为2 432.56,3 131.29,1 794.95 t/(km~2·a),依次属于轻度、中度和轻度侵蚀;不同土地利用方式下坝控小流域的最小产沙降雨量均20 mm以上;(3)不同的土地利用方式对小流域侵蚀产沙影响显著,人类活动明显的阎桥流域多年平均产沙模数大于以林草地为主的洞儿沟流域,而以林地和梯田为主的芦渠流域多年平均产沙模数最小。由此可见,在黄土丘陵沟壑区合理配置不同的水土保持措施,是减少小流域侵蚀产沙的有效途径。     

甘肃天水市对比小流域暴雨洪水侵蚀产沙特性

 为分析黄土丘三区水土保持综合治理对小流域典型暴雨产汇流特性的影响,依据桥子东、西沟对比小流域暴雨洪水泥沙观测资料,结合实地调查对比分析雨、洪、沙特性。结果表明:在降雨差异很小的情况下,其水沙特性差异明显,桥子东沟较西沟洪峰削减率达66.9%,单位面积减洪量1万3336m3/km2,减沙量8534t/km2,2流域的流量和含沙量过程变化趋势基本一致,但西沟变率均大于东沟,且西沟流域侵蚀模数是东沟的3.5倍。桥子东沟流域各项水土保持措施发挥了显著的蓄洪拦沙作用,减洪效益59.9%,减沙效益79.5%;桥子西沟的林草措施减洪效益为6.9%,减沙效益8.4%。     

安塞县侯沟门村新农村建设与水土保持措施配置研究

根据野外天然降雨定位监测试验、野外人工模拟降雨与放水冲刷试验、土壤侵蚀类型遥感监测资料及附近纸坊沟小流域泥沙监测资料等.对安塞侯沟门村不同小流域土壤侵蚀类型及其分布规律和水土保持措施配置进行系统研究,特别是对村庄、道路、裸露坡面硬地面产流产沙规律进行了研究.明确了水土保持综合治理思路和重点及存在的问题,为今后评价土壤侵蚀变化、水土保持规划和综合治理提供科学依据.     

概念性土壤侵蚀模型的建立及在紫色土小流域的应用

概念性土壤侵蚀模型在描述流域基本过程的同时对参数要求较低,现有概念性模型中计算产沙所需参数主要靠律定或借鉴经验值。该文介绍了1个无需流域出口产沙量长序列观测资料来律定且能适用于研究流域的概念性土壤侵蚀模型。模型中引入了分布式水文模型WetSpa Extension作为水文模块,结合流域内试验小区上建立的流量—产沙量经验关系计算侵蚀量,再结合泥沙输移比构建起产沙模块。通过在紫色土地区小流域的应用表明,模型能够得到较合理的流域出口产流量、产沙量以及侵蚀率的空间分布等模拟结果,在没有试验小区的邻近流域地区也具有推广性,且能作为评价水保措施效益的有力工具。该概念性模型对于流域出口泥沙资料稀少的地区具有很高的应用价值和协助流域管理的 潜力。     

称钩河坝系流域水保措施减沙效益分析

以称钩河坝系流域降水、径流、泥沙和水土保持措施的5 a监测统计数据为依据,Quick Bird卫星影像为主要数据源,在ArcGIS 9.3及Region Manager 5.5软件支持下,研究该坝系流域降雨变化和水保措施对径流和产沙量变化的影响,分析坝系水土保持措施拦沙效益。结果表明:2007—2011年间,水土保持措施建设是该流域径流和侵蚀产沙减少的主要原因,其中坡面治理措施面积增加133.04 hm²,坝系流域总控制面积达到8 843.58 hm²,占流域总面积的54.80%。坝控范围内年平均侵蚀模数为18.80 t/km²,侵蚀模数减少5 581.20 t/km²。     

小流域非点源污染管理措施的多目标优化配置模拟

基于"风险评价—规划分区—分别管理"的非点源污染管理思路,采用非点源污染风险评价模型、最佳管理措施(best management practices,BMPs)评估体系及非支配排序遗传算法相耦合的方式,对北京怀柔区北宅小流域非点源污染进行不同空间尺度下最佳管理措施空间优化配置模拟,为小流域非点源污染最佳管理措施的实施,提供决策支持。研究结果表明:1)非点源污染潜力高风险区为距离河道较近受人为活动影响明显的居民区、养殖场和耕地,为重点管理区;2)根据污染物污染控制功效、成本投入以及景观美学功效3个方面综合评价结果对拟实施的BMPs进行综合评分排序,人工湿地、入渗池、绿屋顶、植物蓄留池等以下渗过程为主要污染控制机制类措施,可作为BMPs情景配置的优选措施;3)不同空间尺度下最佳管理措施空间优化配置模拟表明,流域层面BMPs最优方案为为生物滞留池0,湿式滞留池105 000元,占总成本的8%,入渗沟469 560元,占总成本的92%,总氮、总磷年污染负荷量综合削减率45%;村庄层面BMPs优化配置方案为生物滞留池3 105元,占总成本的0.8%;湿式滞留池21 000元,占总成本的5.6%;绿屋顶216 306元,占总成本的64%;透水性路面11 0736元,占总成本的29.6%。总氮、总磷年污染负荷综合削减率能够达到46%;农户层面BMPs优化配置方案为绿屋顶0元;雨水罐38元,占总成本的2.5%;生物滞留池675元,占总成本的44.5%;透水性路面805元,占总成本的53%。总氮和总磷两种污染物的年污染负荷削减率65%。     

Integration of modified universal soil loss equation (MUSLE) into a gis framework to assess soil erosion risk

Soil erosion is an important economic and environmental concern throughout the world. In order to assess soil erosion risk and conserve water and soil resources, soil erosion modeling at the watershed scale is urgently needed. This study integrated the Modified Universal Soil Loss Equation (MUSLE) in a Geographic Information System (GIS) framework in the form of a tool called ArcMUSLE, an extension of ArcGIS® software, to assist soil and water conservation agencies in soil erosion risk assessment and prioritization of critical areas for soil erosion control practices. With widely available spatial data, this tool can be applied to determine curve numbers, to estimate runoff, peak flow, and soil loss for a rainfall event within a watershed. An application example for a watershed in Black Hawk County, Iowa, USA, is presented. Copyright © 2008 John Wiley & Sons, Ltd.     

试论我国水土保持学科的性质与定位——川陕“长治工程”中期评估考察的思考

 以小流域为单元实施山、水、田、林、路、渠综合治理的理论与技术体系是在我国水土保持长期生产实践和科学研究中形成的具有中国特色的水土保持学科体系。通过川陕"长治工程"中期评估考察,分析"长治工程"小流域综合治理的特色与创新,并据此讨论我国水土保持学科的性质与定位。水土保持学科无论从法律地位还是学术地位,均应归属于资源保护与利用的范畴,与环境保护和生态学科的本质区别在于,水土保持更具有突出的生产功能。现阶段水土保持学科仍应首先赋予其防治水土流失,治理江河,提高农业生产综合能力,发展农村经济,改善农村基础设施及农民生活质量的内涵,并努力使之与农村生态建设结合,以不断深化和丰富其内涵,同时应在开发建设项目水土保持、饮用水水源地水土保持等方面拓展其学科外延。     

森林火灾流域侵蚀泥沙来源指纹技术研究进展

指纹识别技术是量化流域侵蚀泥沙来源的有效手段,如何应用于火烧流域,仍有一些问题值得探讨。通过回顾相关文献,总结森林火灾通过植被、土壤和灰烬加剧土壤侵蚀的机制,介绍应用指纹技术研究火烧流域泥沙来源的案例,重点分析放射性核素、矿物磁性、物理性质、地球化学元素和有机组分等指纹因子在火烧迹地的含量和性质变化,论述各类指纹因子在火烧流域泥沙来源研究中的适用性,并提出未来应重点关注指纹技术的物理基础、火灾后土壤性质的时空变化规律、指纹因子稳定性验证、燃烧灰烬的影响以及大粒径泥沙的识别等问题。为促进火烧迹地指纹识别技术的研究、理解森林火灾对于流域产沙格局的影响、提升火灾流域水土保持和生态修复的有效性提供理论依据。     

Changing sediment yield as an indicator of improved soil management practices in southern Brazil

Catchment-level soil and water conservation programmes have been widely employed in Brazil. An important component of these programmes is the implementation of water and sediment monitoring projects to evaluate the impact of changes in soil management on water resources. In general, results from monitoring projects have been inconclusive, due to a series of difficulties associated with data collection and limited timeframes. This study presents results from a hydrosedimentological monitoring project undertaken in a small (1.19 km²) rural catchment in Southern Brazil before and after the introduction of conservation tillage practices implemented by the RS-RURAL — Program Against Rural Poverty. These practices, including use of winter cover crops and minimum tillage tobacco cultivation, were gradually adopted by local farmers. Data on precipitation, runoff volume, maximum flow and sediment yield were assembled for representative storm events occurring between May 2002 and March 2006, and analyzed to identify changes in the storm runoff and storm-period sediment response of the study catchment. The results provide evidence of statistically significant reductions in storm runoff, maximum flow rate and sediment yield after implementation of the conservation practices. Sediment sources were also investigated using the fingerprinting technique and this work demonstrated a statistically significant reduction over the study period in the proportion of the sediment contributed by fields (62% to 54%) and unmetalled roads (36% to 24%). This reduction was offset by an increased contribution of sediment from channel sources (2% to 22%). The increased proportion of sediment mobilized from the channel is in part a function of the reduced contribution from the two other sources, but it also reflects the reduction in sediment inputs to the channel from the fields and unmetalled roads, which results in an increase in the energy available for channel scour. Results emphasize the complexity of the relationship between sediment yield, the effects of climactic variability, and changes in land use and management.     

An integrated watershed modelling framework to explore the covariation between sediment connectivity and soil erosion

Quantitative identification of the covariation between sediment connectivity and soil erosion can contribute to provide the key information for watershed sediment management. However, this covariation and its spatiotemporal response mechanisms are still unclear, especially whether this covariation can be used as a basis for identifying critical source areas of sediment in large-scale ecological restored watersheds. In this study, an integrated methodology framework by the revised universal soil loss equation (RUSLE), index of connectivity (IC) and sediment delivery ratio (SDR) was proposed to visually assess the spatiotemporal characteristics of erosion and sediment yield processes in the Yanhe Watershed with large-scale ecological restoration from 1985 to 2020 and to identify the covariation between sediment connectivity and erosion in subbasins. The soil erosion estimated by RUSLE has decreased by over 80% since 1985 owing to increased vegetation cover and the effective implementation of soil conservation measures, but the upper reaches still have high erosion intensity due to differences in specific controlling factors such as topographic conditions and land cover, requiring focused soil conservation practice. The IC results showed that as the vegetation restoration and soil conservation measures in the Yanhe Watershed varied from year to year, their spatial and temporal patterns had a strong influence on the distribution of sediment connectivity, and some local areas in the middle reaches showed local minima of IC in 1995, 1998 and 2010 mainly due to the implementation of long-term ecological restoration project. The developed IC-Erosion maps indicated that areas with high connectivity but low erosion accounted for over 60% of the total watershed area from 1985 to 1999, demonstrating a reverse correlation between sediment connectivity and erosion. Meanwhile, over 40% of the erosion occurred in a few areas (approximately 20%) with high connectivity and high erosion from 2000 to 2004, which can be characterized as the critical areas of erosion. The methods and results of this study provide ideas for separately defining both erosion and connectivity and quantifying bi-variable erosion–connectivity classification, which can be easily viewed on a scatterplot.     

Changing sediment yield as an indicator of improved soil management practices in southern Brazil

Catchment-level soil and water conservation programmes have been widely employed in Brazil. An important component of these programmes is the implementation of water and sediment monitoring projects to evaluate the impact of changes in soil management on water resources. In general, results from monitoring projects have been inconclusive, due to a series of difficulties associated with data collection and limited timeframes. This study presents results from a hydrosedimentological monitoring project undertaken in a small (1.19 km²) rural catchment in Southern Brazil before and after the introduction of conservation tillage practices implemented by the RS-RURAL — Program Against Rural Poverty. These practices, including use of winter cover crops and minimum tillage tobacco cultivation, were gradually adopted by local farmers. Data on precipitation, runoff volume, maximum flow and sediment yield were assembled for representative storm events occurring between May 2002 and March 2006, and analyzed to identify changes in the storm runoff and storm-period sediment response of the study catchment. The results provide evidence of statistically significant reductions in storm runoff, maximum flow rate and sediment yield after implementation of the conservation practices. Sediment sources were also investigated using the fingerprinting technique and this work demonstrated a statistically significant reduction over the study period in the proportion of the sediment contributed by fields (62% to 54%) and unmetalled roads (36% to 24%). This reduction was offset by an increased contribution of sediment from channel sources (2% to 22%). The increased proportion of sediment mobilized from the channel is in part a function of the reduced contribution from the two other sources, but it also reflects the reduction in sediment inputs to the channel from the fields and unmetalled roads, which results in an increase in the energy available for channel scour. Results emphasize the complexity of the relationship between sediment yield, the effects of climactic variability, and changes in land use and management.     

川北紫色土区典型小流域径流特征分析

针对日益加剧的四川紫色土地区水土流失情况,选取四川省南部县鹤鸣观小流域为研究区,对其径流特征进行探讨分析。结果表明,该流域径流季节变化与年际变化都较大,降雨量与径流量、土壤侵蚀模数与径流之间相关性与流域水土保持措施的实施与否关系密切,水保措施起到了很好的减水减沙效果。本研究为该区水资源合理利用与川北紫色土区流域水土流失机理分析以及区域水土保持治理提供了一定的科学依据。     

黄土丘陵区淤地坝建设后小流域泥沙拦蓄与输移特征

了解淤地坝建设后小流域泥沙拦蓄与输移的变化特征对正确认识和评价淤地坝的减蚀作用有重要意义.该文通过对黄土丘陵区王茂沟流域1953-2015年不同时段内淤地坝的拦沙量和流域出口输沙量的分析,研究了坝系建设后泥沙拦蓄、输移和侵蚀的变化过程与特征.研究表明,王茂沟流域年均拦沙模数呈减少-增加-再减少的波动变化趋势;流域年均输沙模数呈先增加后减少的变化趋势;1953-1986年期间,不同阶段的年均侵蚀模数变化不大,1987年后呈显著下降趋势.流域治理后期与初期相比,年均拦沙模数、输沙模数和侵蚀模数分别下降了79.3％、90.6％和83.9％.淤地坝建设初期,有效库容对流域拦沙模数和输沙模数的变化有重要影响,侵蚀性降雨频发和较低的水土流失治理度是侵蚀强烈的主要因素;流域治理后期,侵蚀性降雨及其发生频次的减少,水土流失治理度的提高与稳固,是流域拦沙、输沙和侵蚀产沙显著下降的主要原因.淤地坝在控制流域侵蚀产沙、减少泥沙输移方面作用显著,但要达到持续有效的作用,坡面治理不容忽视,两者兼顾是黄土丘陵区水土保持的必由之路.