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1.
A. N. Nunes C. O. A. Coelho A. C. de Almeida A. Figueiredo 《Land Degradation \u0026amp; Development》2010,21(3):260-273
This paper analyses the effects of land abandonment on runoff and sediment yield in a central inland area of Portugal. Rainfall simulation experiments were performed in areas of traditional land use (land cultivated with cereals) with various types of soil plant cover associated with the period of abandonment (4–5 years, 15–20 years and 30–40 years) in two different seasons, namely under very dry conditions and after a long wet period. Statistical analysis showed a notable difference between the cultivated soils and those abandoned for a long period of time, which included appreciable vegetation recovery, higher organic matter content and negligible overland flow and soil loss. Cereal cultivation, in particular ploughing, is a very negative land management practice, due to the high runoff and soil loss. Within 4–5 years a crust develops over abandoned soils with sparse herbaceous plant cover, particularly after a dry season, which enhances runoff and sediment yield. In scrubland and oak plots, although marked water repellency was registered at the end of a dry, warm season, its influence seems to be irrelevant in terms of overland flow and erosion yield. The major factor in controlling overland flow and reducing soil erosion rates appears to be the role played by vegetation in protecting the soil surface and supplying organic carbon to the top layer. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
2.
R. J. Loch 《Land Degradation \u0026amp; Development》2000,11(3):221-240
An Erratum for this article has been published in Land Degradation & Development 11(4) 2000, 399. A study using simulated rain and overland flows was carried out on a 6‐km‐long bund constructed at the NorthParkes Mine, New South Wales, Australia. The bund has been progressively constructed using 5‐m lifts to achieve final heights of 10–20 m. The slope profile consisted of alternate benches and batters of approximately 30 per cent gradient. For the topsoil placed on the bund, properties assessed included infiltration, erodibility, effects of plant cover on infiltration and erosion, and of slope length on erosion. Studies also considered permeability of the underlying spoil material, and compared susceptibility to erosion by overland flows of the two spoil materials available for bund construction. For sites that had been revegetated for one and two years, infiltration increased and soil erodibility decreased with time under vegetation. There were large increases in infiltration with increasing vegetative cover, and high infiltration rates at 100 per cent cover. The soil loss ratio curve fitted to erosion data showed larger effects of cover on erosion than predicted by the universal soil loss equation (USLE). Overland flow studies indicated no effect of slope length on erosion rates, and indicated ‘target’ levels of vegetative cover necessary to prevent rill development. Permeability of spoil underlying topsoil at one site was shown to be high, and unlikely to impede water entry and drainage. Overland flow studies showed marked differences between the two spoils studied in both critical shear for rill initiation and in rill erodibilities. Implications of the results obtained on rehabilitation planning and management are discussed. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
3.
用水平土柱和修正的Green-Ampt模型确定土壤的入渗性能 总被引：3，自引：1，他引：2
土壤入渗能力和降雨产流过程及地下水密切相关。土壤入渗过程决定了灌溉/降雨过程中水分进入土壤的过程,影响了化肥、农药及其他污染物随水分迁移过程以及坡面水文与土壤侵蚀过程等。该研究根据水流在水平土柱中运动的能量要求以及实际测量得到的土壤水分分布,对Green-Ampt模型中含水率分布呈活塞运动推进(即湿润锋内部土壤水分为恒定值)的假定进行了修正。采用更符合实际的呈线性分布的土壤水分分布模型,基于水量平衡和土壤水动力学原理,提出了对应的土壤入渗性能的计算模型。给出了利用修正模型估计土壤入渗性能的方法,计算模型以及计算过程。结果表明,利用修正模型估算得到的土壤入渗性能回归的入渗水量与实际供水量的相对误差为0.66%,说明该修正模型和计算方法具有很高的精度。该文提出的修正模型很好地描述了水分在土壤中的分布,较Green-Ampt入渗模型中的活塞模型更符合土壤水动力学中关于土壤水分运动的分析。将该修正模型与水平土柱试验结合,可以大大地提高土壤入渗性能计算的精度,为以后的土壤水分运动,地表产流计算以及土壤侵蚀等方面的研究提供非常有效的工具。 相似文献
4.
Using the simulation model described in Part I, this paper examines the impact of erosion on soil productivity, how the impact varies according to initial soil conditions and organic matter management and the economic cost of erosion measured as net present value. The reference crop is winter wheat grown in Chunhua in the southern Loess Plateau. Biomass yield is plotted over 100 years for four erosion scenarios represented by 0, 9, 27 and 47 per cent slopes, three initial soil conditions indicated by 0·5, 1 and 2 per cent organic matter, and two management levels determined by high or low levels of reincorporation of organic residues. Calculations of soil productive half‐life (time to half initial yield) and whole‐life (to equilibrial yield) are presented. The principal findings are that decline in soil productivity is caused by both erosion and insufficient return of organic matter. By increasing organic matter input, erosion damage is offset and soil productive life prolonged, but this is a costly strategy. If yield decline caused by erosion is isolated, erosion control is more important on a high organic matter input system. A maximum soil productive half‐life of 600 years is achieved with no erosion, high initial organic matter and return of organic residues; minimum half‐life of 10 years is with high erosion, low initial organic matter and little return of residues. In between, there are complicated interactions that significantly affect the economic cost of erosion and hence the decisions farmers make in investing in conservation practices. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
5.
B. C. Oinam W. Marx T. Scholten S. Wieprecht 《Land Degradation \u0026amp; Development》2014,25(5):483-500
Land use practices and vegetation cover distribution are considered to be the most important dynamic factors that influence the land degradation or the soil erosion of a region. In this study, a Soil Protection Index (SPI) is defined as a function of land use practices and intensity of vegetation cover. This index is used to map the relative degree of protection of topsoil from being eroded by external effects such as rainfall and overland flow. A fuzzy rule‐based model integrated within ArcGIS® has been set‐up and tested with the aim to develop SPI maps. The amount of vegetation cover distribution, that is, Normalized Difference Vegetation Index as proxy parameter and Land Use–Land Cover map are chosen as fuzzy input parameters for the SPI as the desired system output. The approach was tested in the Upper Awash basin in Ethiopia. The output SPI map was qualitatively evaluated against the expert‐defined land degradation risk class, and it was found that locations that are mapped with ‘low and very low’ SPI classes at different time periods of the year have a high potential land degradation risk. Furthermore, socio‐economic data (‘population and livestock densities’) and environmental parameters (‘altitude and soil erodibility’) for the region are used to correlate with the SPI map as an indirect method of evaluation. It is found that population and livestock density explained 68 per cent of the spatial distribution pattern of predicted SPI and an adjusted R‐squared value of 0·681 (p < 0·05) was obtained. It was also found that the SPI distribution over the region for two different time periods, that is, January and July 2001, correlated positively (R2 = 0·41 and R2 = 0·51) with the soil erodibility of the region. The transferability and applicability of the model for different environmental settings or landscapes were tested by mapping the SPI of Italy. This SPI map of Italy was compared with the soil erosion map of Italy produced by the European Soil Bureau. It can be concluded that the SPI map reflects the potential land degradation risk distribution of the case‐study region. Results show that a fuzzy rule‐based model can provide useful preliminary information even without detailed and precise data information for developing appropriate strategies for land degradation assessment vital for sustainable land use management. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
6.
Regional assessment of soil erosion using the distributed model SEMMED and remotely sensed data 总被引：15，自引：0，他引：15
The soil erosion model for Mediterranean regions (SEMMED) is presented and used to produce regional maps of simulated soil loss for two Mediterranean test sites: one in southern France and one in Sicily. The model demonstrates the integrated use of (1) multi-temporal Landsat Thematic Mapper (TM) images to account for vegetation properties, (2) a digital terrain model in a GIS to account for topographical properties and to assess the transport capacity of overland flow, (3) a digital soil map to assess the spatial distribution of soil properties, and (4) a limited amount of soil physical field data. The principle drawbacks of the model are that it does not account for soil particle detachment by overland flow nor for soil surface crusting. The model is most sensitive to the initial soil moisture storage capacity and the soil detachability index. The main advantages of SEMMED are that it simulates processes at a regional scale and, where possible, it uses available data sources such as remote sensing imagery, digital elevation models (DEM) and (digital) soil databases, which usually are not available for smaller catchment areas. Using SEMMED it is possible to produce regional maps of erosion assessments, which are of more practical use in land use planning and land management than simple extrapolations from small plot experiments. 相似文献
7.
Abstract. The Pan‐European Soil Erosion Risk Assessment (pesera ) model was evaluated using existing soil erosion data collected under various types of climate, vegetation, landscape and soil conditions. The data used represent a variety of typical Mediterranean land uses such as winter wheat, vines, olives and bare, stony land prevailing in hilly areas. Using this data, the model was calibrated for sediment transport by overland flow and results compared to measured soil erosion values from runoff plots and a watershed on a monthly basis. The performance of the model was assessed statistically, showing that it can be satisfactorily used for predicting soil erosion rates under the conditions included in the study. The overall model estimate including all the available experimental data was 0.69 t ha?1 yr?1 with a maximum error of 1.49 t ha?1 yr?1. After validation, the model was applied to a small watershed (60 ha) of great ecological importance for the sea turtle Caretta caretta. For this purpose, soil and vegetation maps were compiled from all the necessary data for applying the model. The model was run for three years using daily data from an existing nearby meteorological station. The predicted and measured soil erosion rates for a 7‐month period were 0.31 t and 0.18 t, respectively. Application of the model to each mapping unit showed the over‐riding importance of land use for sediment generation under the given climatic conditions. Bare land, occupying 5.5% of the watershed area, generated up to 69% of the total sediments estimated for the watershed. It is concluded that the pesera model can be used as a regional diagnostic tool under a range of soil, topographic and climatic conditions for identifying the best land use type and vegetation cover to protect hilly areas from soil erosion. The calculated overall root mean square error for the model is 0.06 t ha?1 yr?1, compared to a soil erosion rate of 0.04 t ha?1 yr?1, which can be tolerated for protecting the area for the sea turtle. 相似文献
8.
密云水库土门西沟流域非点源污染负荷估算 总被引：2，自引：1，他引：2
密云水库水质影响北京市地表饮用水源质量,非点源污染成为密云水库水质下降的主要原因。为了满足水资源管理规划,在密云水库土门西沟小流域内根据不同的水土保持措施选择6个径流小区,主要有：板栗林、油松林、刺槐林、混交林、灌木林、梯田,于2007年对小区地表径流进行水质水量的监测。运用RUSLE公式和SCS法估算流域内不同水土保持措施的非点源污染负荷,利用ArcGIS工具绘制了土壤侵蚀量空间分布图。结果表明：土门西沟小流域非点源污染物主要来源于土壤侵蚀,泥沙中的吸附态是非点源污染物存在的主要形式;其次土门西沟小流域不同水土保持措施单位面积的污染负荷输出由大到小排列顺序为,经济林＞阔叶林＞灌木林＞针叶林＞混交林＞梯田。研究结果表明减少经济林来增加混交林用地面积,提高水源林的覆盖率,梯田可以维持现有的用地状况,禁止陡坡栽种农作物,坡脚和沟道农地采取梯田的耕种方式,以此来达到控制非点源污染的目的。跟以往研究得出的结论相反,梯田非点源污染负荷比林地小,主要是因为梯田相对坡耕地大大增加了地表入渗量,此外是因为梯田施用有机肥料,减少非点源污染。 相似文献
9.
The Pyrenean and Pre‐Pyrenean mountain areas have been intensively used at least since roman times, but nowadays depopulation has lead to widespread land abandonment without a steering land‐management. Vegetation recovery is weak in most abandoned fields. Soil formation and characteristics are conditioned by this fact, and for this, soils show past degradation processes and are mostly predominant factors for continuing land degradation or restoration. Three study areas were set up along a climatic gradient with increasing summer water deficit in the sub‐humid zone between the Central Pyrenees and Pre‐Pyrenees. Soil survey combined with experiments for the determination of infiltration, runoff and erosion were applied for understanding the degradation history and the future development of the soils. All areas are dominated by Entisols, but also Inceptisols and Alfisols are found, and even soils with hydromorphic features. The soils show signs of heavy erosion. The parental material determines the nutrient supply and the general chemical properties. All sites show a weak water storing capacity, as a result of the removal of fine material by erosion and due to the depletion of soil organic matter. In addition, infiltration capacity and runoff generation are high within the studied areas, averaging between 27 and 37 per cent. The driest area studied shows an ongoing trend to degradation, with high erosion rates combined with a high degradations status of the soil. The other areas are characterised by a patchy pattern of soil degradation and regradation processes. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
10.
半干旱草地上的生态地理响应: 综述 总被引：4，自引：0，他引：4
The ecogeomorphic processes occurring on semiarid rangelands are reviewed, with emphasis on the source-sink relations and positive feedback loops that existed between shrub patches and intershrub areas, and the way livestock presence affected these interactions. Compared with intershrub areas, the shrub patches had a higher soil porosity, infiltration capacity, water-holding capacity, hydraulic conductivity, structural stability, and organic matter content, and lower bulk density. These differences derived from a host of processes whose intensity was less in the shrub patches, including raindrop impact, mechanical crust formation, overland water flow, soil erosion, evaporative moisture loss, and flock trampling. There was also greater shading of the soil surface; soil and litter deposition; water accumulation; microbial, fungal, and mesofaunal activities in the shrub patches. The overland flow of water carried soil and litter from the intershrub areas to the shrub patches and resulted in microtopographic modifications that tended to strengthen these source-sink relations. Grazing had an impact on these processes, not only at the shrub-intershrub scale but also within the intershrub areas, through the creation of highly compacted trampling routes. The combined role of the above ecogeomorphic processes was to maintain the rangeland’s functionality. Without these inter-relationships, water loss, soil erosion, and nutrient depletion would occur at the hillside scale, causing degradation of the landscape. 相似文献
11.
J. L. Ternan A. G. Williams A. Elmes C. Fitzjohn 《Land Degradation \u0026amp; Development》1996,7(4):337-351
Bench-terracing and Pinus afforestation have been extensively adopted as a means of soil conservation in Spain. This paper questions the appropriateness of this technology to extensively gullied soils and sediments of the Raña formation of central Spain. Bench-terracing has markedly altered the characteristics of the surface soil horizon as compared with nearby undisturbed matorral (natural scrub) vegetation. The construction process and resultant bench-terrace morphology have imposed a new, more spatially structured pattern in soil properties giving enhanced opportunities for overland flow generation and erosion. The terracing has exposed subsurface Bt horizons on inner treads and lower risers, producing a very compact clay rich surface horizon, low in organic carbon and of poor structural stability. Despite subsoiling hydraulic conductivity is very low. Excavated soil material is ploughed sideways to partially bury the original surface horizon and form part of the next riser downslope. Downslope drainage on the terraces gives rise to soil moisture contents approaching saturation on the lower risers and treads. Consequently only small rainfall inputs are required to initiate ponding and overland flow generation on sloping treads. Rainfall simulation demonstrates the importance of antecedent soil moisture to runoff generation, and the role of vegetation and organic matter in retaining water. Erosion bridge measurements show that erosion rates on sloping treads are as high as those recorded on gully sidewalls. Gully sidewall erosion is also accelerated by runoff waters shed from terrace treads. Management of native matorral vegetation may provide a more sustainable approach to soil conservation than bench terracing with afforestation. 相似文献
12.
基于土壤~(137)Cs监测的土壤侵蚀与有机质流失——以密云水库为例 总被引：3，自引：0，他引：3
本文运用137Cs核素示踪技术,研究北京重要的水源供应地密云水库周边地区及白河上游地区土壤侵蚀状况与有机质流失状况及其相互之间的量变关系。试验结果表明:0～20cm土层中山坡上137Cs含量低于坡中、坡下,但若山顶具有缓坡或山角下具有陡坡则137Cs含量变化规律相反。根据水利部标准与土壤137Cs监测结果,密云水库周边大部分地区基本属于轻度侵蚀和中度侵蚀,部分地区侵蚀情况严重,达到了剧烈侵蚀的程度。不同土地利用方式对土壤有机质分布有很大影响,有机质含量分布为灌丛>林地>果园>农田;上游地区有机质含量高于水库周边地区土壤,表明人为活动加剧了土壤侵蚀和有机质的流失。对于景观单一,地域较小的采样区进行三次曲线数学模拟,其相关系数高达0.9左右,表明在监测土壤137Cs、210Pb含量变化的同时,可以利用小区域数学模型直接预报预测土壤有机质含量的变化。 相似文献
13.
土壤侵蚀过程中坡面流水力学特性及侵蚀动力研究评述 总被引：5，自引：0，他引：5
土壤侵蚀动力过程是水流和土壤两者相互作用的复杂物理过程,而含沙水流是土壤侵蚀的主要动力,深入理解坡面流水力学特征及侵蚀动力是研究土壤侵蚀动力学规律的基础.本文从坡面流水力学特性及侵蚀动力,包括:流速、水深、流态、阻力规律以及坡面流的切应力、冲刷动力、运动能量等多方面对国内外关于土壤侵蚀动力过程研究进行了系统深入的评述,并探讨了研究中存在的问题,重点指出:坡面流作为三维、非恒定非均匀沿程变量流,流动形态千变万化,坡面状况较为复杂,其均匀流理论远不能真实反应自然界复杂地表状况下的水流水力学特性及其变化规律.开展复杂地表的水流运动过程、水力学参数变化规律及坡面侵蚀水动力过程研究是今后土壤侵蚀水动力学研究的重要方向,这对于深入了解土壤侵蚀水动力过程的内在机制、构建物理侵蚀模型具有重要的研究意义. 相似文献
14.
退耕驱动的近地表特性变化对土壤侵蚀的潜在影响 总被引：8，自引：0，他引：8
张光辉 《中国水土保持科学》2017,(4):143-154
黄土高原是我国、乃至全球土壤侵蚀最严重的区域之一,侵蚀强度及时空分布特征受近地表特性的显著影响.退耕还林(草)工程大面积的有效实施,势必会引起近地表特性(土壤理化性质、植被茎秆、枯落物、生物结皮、根系系统)的显著变化,进而对坡面径流的水动力学特性及侵蚀过程产生影响.本文从退耕驱动的近地表特性变化、近地表特性变化对坡面径流水动力学特性的影响、近地表特性变化对土壤侵蚀过程(土壤分离、泥沙输移、泥沙沉积)的影响及其机制、区域土壤侵蚀对退耕的响应4个方面较为系统地总结近几十年国内外的研究成果,并提出了目前亟待强化的研究领域.这对理解退耕坡面土壤侵蚀过程及其动力机制、建立植被覆盖坡面的土壤侵蚀过程模型、评价退耕坡面的水土保持效益,具有重要的理论意义. 相似文献
15.
16.
《Land Degradation \u0026amp; Development》2017,28(7):2290-2297
Reclamation following mining activities often aims to restore stable soils that support productive and diverse native plant communities. The soil re‐spread process increases soil compaction, which may alter soil water, plant composition, rooting depths, and soil organic matter. This may have a direct impact on vegetation establishment and species recruitment. Seasonal wet/dry and freeze/thaw patterns are thought to alleviate soil compaction over time. However, this has not been formally evaluated on reclaimed landscapes at large scales. Our objectives were to (1) determine soil compaction alleviation, (2) rooting depth, and (3) spatial patterns of soil water content over a time‐since‐reclamation gradient. Soil resistance to penetration varied by depth, with shallow compaction remaining unchanged, but deeper compaction increased over time rather than being alleviated. Root biomass and depth did not increase with time and was consistently less than the values in the reference location. Plant communities initially had a strong native component, but quickly became dominated by invasive species following reclamation, and soil water content became increasingly homogeneous over the 40‐year chronosequence. Seasonal weather patterns and soil organic matter additions can reduce soil compaction if water infiltration is not limited. Shallow and strongly fibrous‐rooted grasses present in reclaimed sites added organic matter to shallow soil layers, but did not penetrate the compacted layers and allow water infiltration. Strong linkages between land management strategies, soil properties, and vegetation composition can advance reclamation efforts and promote heterogeneous landscapes. However, current post‐reclamation management strategies are incompletely utilizing natural seasonal weather patterns to reduce soil compaction. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
17.
A principal challenge in erosion control is the integration of the many technical and non‐technical issues that affect the acceptance of soil conservation measures by land users. This first paper in a three‐part series considers the main criteria at farm level: biophysical efficiency; productivity and sustainability; and socio‐economic acceptability. A model is developed to integrate these various components into a decision‐making framework for soil conservation at the farm level. With the particular conditions of the Loess Plateau in China, land degradation comprises a number of key biophysical and socio‐economic variables. The model components therefore include available water storage capacity of the soil as an index of productivity, the organic matter and mineral soil balance to reflect the major changes to the soil when eroded, and cost‐benefit analysis to determine the economic wisdom of devoting household resources to land improvement. The model is calibrated using data from the Nihegou Catchment near Chunhua in the southern part of the Loess Plateau. Through simulation runs, this model enables a better understanding of erosion–productivity–time relationships. Although relatively simple, the model successfully encompasses the processes of greatest significance to agricultural development in this part of China. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
18.
A one-dimensional mathematical model, termed sediment transport rate-based model, is developed for determining rainfall-induced soil erosion and sediment transport. The model is comprised of (1) the kinematic-wave equation for overland flow, (2) a transport rate-based advection equation for rainfall-induced soil erosion and sediment transport, and (3) a semi-Lagrangian algorithm for numerical solution of the soil erosion and sediment transport equation. A series of soil flume experiments under simulated rainfalls were conducted to simulate the overland flow and sediment transport and to test the sediment transport rate-based model. Numerical results of sediment transport rate-based model indicate that (i) hydrographs display an initial rising limb, followed by a constant discharge and then a recession limb; (ii) sediment transport rate graphs exhibit the distributions similar to the hydrographs; and (iii) sediment concentration graphs show a steep-receding limb followed by a constant distribution and a receding tail. The numerically simulated hydrographs, sediment transport rate and concentration distributions are in good agreement with those measured in laboratory experiments, demonstrating the efficacy of the transport rate-based model. 相似文献
19.
F. H. Tonneijck M. Velthuis W. Bouten E. E. Van Loon J. Sevink J. M. Verstraten 《European Journal of Soil Science》2016,67(2):226-236
Volcanic ash soil contains large stocks of organic matter per unit area. A large proportion of organic matter is stored in the subsoil; therefore, a thorough understanding of its vertical distribution is needed to predict the effects of change in climate and land use. Faunal bioturbation is often cited as the dominant process that affects the vertical distribution of organic matter. An additional but often overlooked process is change in the volume of the soil. Such change might affect the vertical distribution of organic matter by changing the position of the soil surface, which can affect the soil‐forming processes related to depth, such as weathering, decomposition, bioturbation and rooting. We calculated the change in volume with geochemical mass balance equations, and showed the effect of change in soil volume on the vertical distribution of organic matter using a dynamic model. Then we evaluated the plausibility of the model concept with an independent model for parameter identification and through a model sensitivity analysis. Results show that volume change is a major soil‐forming process that determines the vertical distribution of organic matter in volcanic ash soil as the active bioturbation zone moves upwards in response to soil thickening. 相似文献
20.
岩溶坡地不同利用类型土壤入渗性能及其影响因素 总被引：14，自引：3，他引：11
为了探讨岩溶坡地不同土地利用类型土壤入渗性能差异及其影响因素,该文利用环刀法测定了不同利用类型石灰岩土壤的入渗过程曲线,并分析了孔隙状况、颗粒组成和土壤结构等对入渗的影响。结果表明：土地利用类型对岩溶坡地土壤入渗性能影响较大,初始入渗速率和稳定入渗速率均表现为灌丛＞果园＞草地＞旱地。灌丛地表下层（＞15～30 cm）平均稳定入渗速率8.11 mm/min,最小值4.22 mm/min;旱地地表下层平均稳定入渗速率0.46 mm/min,最小值仅0.13 mm/min。旱地表层以下存在显著的入渗阻滞层。岩溶坡地土壤入渗性能与有机质、水稳性团聚体和孔隙度有显著相关性。非毛管孔隙在入渗初期的作用大于后期,＞0.25 mm水稳性团聚体含量是影响稳定入渗速率的重要因素。该文为进一步研究岩溶坡地旱涝灾害、水土保持和水资源开发利用等提供了理论依据。 相似文献