近十年土壤侵蚀与水土保持研究进展与展望

在当今生态文明背景下,土壤侵蚀与水土保持研究迎来了新的发展机遇和挑战。本文首先采用文献计量学方法,定量分析了近10年来国内外土壤侵蚀与水土保持学科发展现状。在此基础上,结合社会需求的变化,阐明了学科发展需求与存在问题。最后,提出了本学科研究的重点领域与方向:水文过程与侵蚀产沙机理,土壤侵蚀过程及其定量模拟,全球变化下土壤侵蚀演变及其灾变机理,社会经济系统—水土流失的互馈过程,以生态功能提升为主的土壤侵蚀防治,以及土壤侵蚀研究新技术与新方法等。     

Soil crusts and deposits as sheet erosion indicators in southern Mali

Rills are indicators of erosion, easily recognized by farmers and extension workers. However, they are rare on fields in Mali with slopes of 0–3%, even though run‐off and sheet erosion may be a problem. The suitability of three other soil surface features as erosion indicators was therefore investigated: (1) structural crusts formed by rainfall impact without lateral soil movement; (2) in situ depositional crusts, formed by sedimentation leaving the finest particles on top; and (3) run‐off deposits of fine and coarse sand, formed after the removal of finer particles. Feature (1) occurred on the elevated parts and ridges, whereas (2) and (3) occurred in lower parts and in furrows. Soil cover with a run‐off deposit of coarse sand proved to be a suitable indicator and this was well explained by erosion risk: a 2% increase in slope related to a 9% increase in deposit cover. The extent of this deposit also related well to cotton yield from the previous season: a 30% increase in deposit cover was reflected in a 23% decrease in cotton yield. Only a few farmers confirmed that the deposits were produced by erosion. It is recommended that soil and water conservation programmes pay more attention to the presence of crusts and deposits.     

Soil erosion and participatory remediation strategy for bench terraces in northern Thailand

This study was carried out in Pang Prarachatan village, which is located in Chiang Rai province of northern Thailand. The farmers in this village construct bench terraces to reduce soil erosion and increase plant productivity. However, severe soil erosion occurs frequently on the bare bench terraces. This study investigates the impact of bench terracing on soil erosion. The use of weeds and plant residues to control soil and nutrient losses were also investigated using model slope plots and an artificial rainfall system. Finally, the knowledge gained from this study was transferred to the farmers through a workshop in the village, and their acceptance of the results was evaluated by means of a questionnaire. The severity of soil erosion is thought to vary according to the structure of the bench terrace and the ground cover conditions. Rills are the primary form of erosion on bare bench terraces. In addition, some rills develop into gullies that can run from the upper terrace down to the lower terrace. Nevertheless, rills and gullies are rarely found on weed-covered terraces. Moreover, the results of an erosion experiment using model slope plots and artificial rainfall systems showed that plots covered with weeds and plant residues had much less surface runoff and soil and nutrient losses than bare soil. The amounts of nitrogen and phosphorus absorbed by weeds were 4.7 and 2.3 times smaller than the nitrogen and phosphorus losses due to soil erosion, respectively. The results of the field surveys and model slope experiment were announced to the farmers through participatory workshop in August 2003. The first questionnaire, conducted just after the workshop, clearly showed that around 90% of the farmers agreed to cover their slopes with weeds and plant residues so long as it did not affect soil fertility and plant growth. However, the second questionnaire, conducted in January 2004, showed that only 29% of farmers were covering the bench terraces or non-terraced slopes in their farmlands with weeds and plant residues. Therefore, participatory activities should continue to be held regularly in order to ensure greater acceptance and practice of soil conservation on the part of the farmers.     

Soil erosion from a single rainstorm over an area in East Lothian, Scotland

Abstract. An area of about 24 km² in arable East Lothian, Scotland, was examined for soil erosion by water following a severe rainstorm in October 1990. Significant erosion was found in only 10 fields out of 26.5 in an area where topography, soils and cropping suggest a high erosion risk. Doubt is cast on some assessments of the widespread risk of significant soil erosion by water in arable areas of the UK.     

Soil conservation policy measures to control wind erosion in northwestern Europe

Wind erosion is not as significant or a widespread problem in Europe as in dryer parts of the world, but it can cause major damage in small areas. The hazard is greatest in the lowlands of northwestern Europe with more than 3 million ha at high-potential wind erosion risk. Crop damage and off-site damage have prompted farmers and policymakers to pay more attention to wind erosion control. A great variety of measures have been developed in the last decades. Most farmers, however, only use measures to protect their high value crops. In existing policies, little attention is paid to the off-site effects and long-term effects of wind erosion. There are no direct policy measures at a European level to control soil erosion, and few measures exist in individual Member States. Agricultural or environmental EC policies offer different policy tools to approach the wind erosion problems related to agricultural practices. Tools like subsidies for the re-afforestation of arable land can help regional policy makers with the implementation of wind erosion control measures. A case study concerning the ‘Code of Good Agricultural Practice’ shows that regional differences result in different control measures that fits best given the physical, social and economic context. The formulation of the practical details of such code should therefore remain a task of the local or regional government. The main objectives of a Code of Good Agricultural Practice could be formulated at national or European level.     

油松林枯落物层防止溅蚀的研究

28年生油松人工林内天然降雨的溅蚀试验结果表明,当I₃₀为0.07mm/min或P0为3.57mm时,无枯落物层覆盖的林地发生溅蚀,当I₃₀为0.25mm/min或Po为45.8mm时,具1cm枯落物层的林地不发生溅蚀。从溅蚀月动态看出,7、8月份占全年溅蚀量的70%以上。在同一土壤和同一坡度条件下,I₃₀、P₀、H₁是溅蚀发生的主要因素,且溅蚀量与其呈二次多项式回归关系。但当枯落物层具有一定厚度时溅蚀与其它因素无关。具有1cm厚的枯落物层即可防止土壤溅蚀量的79.7%.     

基于WEPP模型的水土保持措施因子与侵蚀量关系研究

水土保持措施能够有效减少水土流失,是土壤侵蚀过程中的一个重要影响因子。以北京市延庆县水土保持科技示范园的径流小区观测数据为基础,利用WEPP模型模拟了坡面不同水土保持措施下的侵蚀量,结果表明:(1)植被盖度与侵蚀量呈负相关关系,植被盖度越高侵蚀量越少,当盖度50%时侵蚀量会显著减少,且植被有效盖度的阈值为70%;(2)梯田的土壤侵蚀过程主要发生在田坎处,水平田面几乎没有水土流失,侵蚀量与田坎高成正比,与田面宽成反比。在北方土石山区,水平梯田田坎高度不宜超过2.5 m,田面宽不宜小于5 m;(3)粮—草间作能有效减少土壤侵蚀量,且草带所占比例越大减蚀效益越好。在水土保持为主的坡耕地上适合推广粮:草比为2:4的间作配置模式。研究结果对于北方土石山区的土壤侵蚀研究以及水土保持措施的配置具有一定参考意义。     

Soil carbonation processes as evidence of tillage-induced erosion

Tillage-induced soil erosion or redistribution increases spatial variation of several soil properties and often reduces the productive capacity of soil resources. Our objectives were to identify the extent of this type of erosion by observing the changes in soil morphological properties in the field and analysing its possible effects on soil productivity. The study was initiated in 2001 and conducted at two irrigated sites located approximately at Terena, Alandrol, 80 km east of Évora, Portugal. They were planted to corn (Zea mays L.) during this study, but have a long history of agricultural use with a trend toward increasing intensity in recent years. Soils in the field studies are classified mainly as Calcaric Regosols, Calcaric Cambisols, Luvisols and small areas of Fluvisols. The amount of erosion was estimated by simulation and verified by describing the lithology and measuring soil carbonates. The presence of carbonates in the superficial Ap horizons of soils that were previously devoid of this compound, provide evidence of soil redistribution: (1) in soils derived from calcareous parent material, this is the result of a re-carbonation process; (2) in soils derived from non-calcareous parent material the presence of carbonates in the superficial Ap horizons results from a carbonation process. On both sites, A and B, approximately 17% of the soils sampled were either carbonated or re-carbonated. Carbonation and re-carbonation of soil profiles confirmed that tillage had redistributed the soil-ploughing layer over time. Decreased corn yield was also observed as slope increase. If current agricultural practices are continued in this area, a decrease in soil quality and maximum yield on higher slopes can be expected.     

African soil erosion — nature undone and the limitations of technology

A wide range of mechanical soil conservation techniques commonly used in Africa are reviewed in a politico-economic framework. Three factors within this framework play a significant role in the adoption of mechanical soil conservation techniques. These are: (a) land considerations, such as land availability and tenure, and farm size; (b) capital and labour constraints; and (c) access to, and functioning of, institutions. Hypotheses which are concerned with the relationships between these factors and the likelihood of farmers adopting soil conservation techniques are introduced. Case studies drawn from Kenya, Lesotho, Malawi, Swaziland and Sierra Leone, as well as from Jamaica, are used to test these hypotheses in relationship to such techniques as terracing, grass strip cultivation, bunding, and contour cultivation. Greater reliance on local knowledge and indigenous soil conservation techniques seems to provide the best solution to the introduction of mechanical soil conservation techniques.     

Satellite remote sensing for water erosion assessment: A review

Water erosion creates negative impacts on agricultural production, infrastructure, and water quality across the world. Regional-scale water erosion assessment is important, but limited by data availability and quality. Satellite remote sensing can contribute through providing spatial data to such assessments. During the past 30 years many studies have been published that did this to a greater or lesser extent. The objective of this paper is to review methodologies applied for water erosion assessment using satellite remote sensing. First, studies on erosion detection are treated. This comprises the detection of erosion features and eroded areas, as well as the assessment of off-site impacts such as sediment deposition and water quality of inland lakes. Second, the assessment of erosion controlling factors is evaluated. Four types of factors are discussed: topography, soil properties, vegetation cover, and management practices. Then, erosion mapping techniques are described that integrate products derived from satellite remote sensing with additional data sources. These techniques include erosion models and qualitative methods. Finally, validation methods used to assess the accuracy of maps produced with satellite data are discussed. It is concluded that a general lack of validation data is a main concern. Validation is of utmost importance to achieve regional operational monitoring systems, and close collaboration between the remote sensing community and field-based erosion scientists is therefore required.     

Soil resistance to interrill erosion: Model parameterization and sensitivity

Interrill erosion, which is less visible in the landscape than rill and gully erosion, may cause major sediment deposits in the lower part of cultivated fields. It is often associated with runoff resulting from sealing and crusting, and soil properties such as soil detachability or soil aggregate stability have been used to express soil resistance to interrill erosion processes, i.e., interrill erodibility. From a literature review including more than fifteen erosion models, we have identified three main methods used to measure these properties: aggregate stability and splash cup detachability, methods performed in the laboratory using only a few grams of soil, and standard plot methods that are based on field plot measurements. This difference makes the parameters involved in assessing interrill erodibility dependent upon the scale and the hydrological processes involved and difficult to compare. According to the literature, the sensitivity of actual erosion models to interrill erodibility is lower than the sensitivity to hydrological properties and rill erodibility parameters. This numerical study shows that erodibility measurements from the three major assessment methods give different results regarding the contribution of interrill erosion and show that the sensitivity of erosion modeling to interrill erodibility may in fact be greater than shown in the literature on global sensitivity analysis.     

Soil erosion: An important indicator for the assessment of land degradation neutrality in Russia

This review of soil erosion (SE) studies in Russia focuses on two main tasks: (i) ensuring the completeness and reliability of SE data in Russia, a large country (17.1 million km²) with a variety of natural and socio-economic causes of land degradation, (ii) assessing the possibility of including a SE indicator among the indicators of land degradation neutrality (LDN). A wide range of statistical, remote sensing, mathematical modeling data, the results of scientific and field studies obtained at different levels were analyzed. It is asserted that in Russia the total area of eroded lands and those under erosion risk occupy more than 50% of all agricultural lands, whereas soil fertility of croplands decreased in Soviet time (from 1950s to 1980s) by 30–60% only due to water erosion. However, recent scientific studies indicate a decrease in erosion rate and in the area of eroded land during the last 30–40 years as a result of abandonment of arable land and subsequent overgrown with natural vegetation. The climate change resulting in decrease of the depth of soil freezing, flow of spring runoff also adds to the decrease of soil erosion. The SE indicator was suggested as an important complement to three global LDN indicators. At national and subnational level, it can be interpreted through such indices as “Rate of soil loss” (ton ha-1 yr-1) and “Total soil loss” (1000 tons, in certain area during selected time period). At local level the set of indices can be wider and site-specific, including those obtained through remote sensing data by using the classifier of thematic applications of remote sensing technologies; the example was tested at the local site.     

Soil erosion,regulatory aspects and farmer responsibility: assessing cadastral data

This paper sets out to clarify the factors in soil erosion and soil conservation. The Czech Republic struggles with soil conservation. Shifts in the rural economy, the loss of good-quality agricultural soil to urbanisation, and sub-optimal land management leading to erosion are at issue. Here, we apply quantitative and qualitative methods to assess erosion risk, whilst considering legislative and policy measures and the responsibility of individual farmer. The studied area was the cadastral district of Rtyně-Podkrkono?í. This choice was based on the fact that farmland there is classified as being subject to ‘no risk’ under current reference measures with regard to soil erosion, and yet 18 erosion events in this area were reported over a period of three years. Our results provide evidence that current measures are insufficient. Although applicable standards were followed, the farmland in question has undergone repeated erosion, whilst soil conservation practice has been ineffective. Compared to the farmland owner, who invests in long-term management, we highlight the problem when a land manager prefers short-term returns. Our assessment of soil erosion was focused on repeated erosion reports that were filed in the monitoring system in relation to farmland parcels managed by a company specialising in maize production. The tolerable erosion rate of 4/t/ha/y was exceeded on all land parcels.     

Soil displacement and tillage erosion during secondary tillage operations: the case of rotary harrow and seeding equipment

This study reports the results of a series of experiments that were set up on agricultural land in central Belgium to investigate soil translocation and erosivity resulting from a secondary tillage operation using an implement sequence of a rotary harrow and seeder. Aluminium cubes were used as tracers of soil movement. Results show that soil displacement resulting from tillage with such an implement sequence is far from insignificant. This is mainly related to the relatively shallow tillage depth as well as to the loose initial soil condition of such secondary tillage operations. The calculated value for the tillage transport coefficient k (123 kg m⁻¹ per tillage operation) is comparable with k-values from implements that are considered to be more erosive, like mouldboard and chisel implements. In conclusion, this study shows that tillage erosion not only results from relatively aggressive tillage operations such as mouldboard and chisel passes, but that secondary operations contribute significantly to soil displacement and tillage erosion.     

Soil erosion risk mapping with new datasets: An improved identification and prioritisation of high erosion risk areas

The numerous estuarine, marshy and marine ecosystems along the coastline of Mauritius Island are potential sinks for sediment especially during intense rainfall events when delivery ratios are high at basin outlets. For sustainable environmental management, soil and water conservation measures are needed, as these will better protect the cultivated lands and aquatic ecosystems from the damages associated with excessive soil loss and sediment deposition. Conservation program usually requires focusing available resources on a limited number of priority action areas. Such areas typically have the highest erosion risk and are connected to aquatic ecosystems. An erosion risk mapping model has been applied in this work to find the priority action areas of Mauritius and new datasets representing rainfall erosivity and topographic factors were used compared to a previous application of the same model. Rainfall erosivity was mapped with Fournier Index instead of rainfall depth. The topographic effect was mapped using a function combining slope length and slope gradient (LS) and was based on the unit contributing area algorithm along with land parcels effect. These new datasets improved the erosion risk mapping and the identification and prioritisation of high erosion areas. The prioritisation was done at basin and subbasin scales and considered the location of wetlands. This enabled the identification of basins and subbasins with the greatest erosion risk and towards which conservation measures can be directed for protecting lands on-site and wetlands off-site from environmental damages.     

Applications and limitations of chernobyl radiocaesium measurements in a carpathian erosion investigation,Poland

The bomb-test fallout radionuclide caesium-137, has found increasing application in geomorphological investigations of soil erosion. Comparatively little work has investigated the potential for using ¹³⁴Cs and ¹³⁷Cs derived from the 1986 Chernobyl accident. Results are reported from an agricultural foothill environment in the Beskidy Mountains of southern Poland. The high degree of spatial variability associated with Chernobyl fallout deposition poses considerable limitations on the potential for using radiocaesium measurements to elucidate detailed patterns of soil loss. Despite this problem, the redistribution of radiocaesium from field plots to terrace edges suggests a means for estimating the overall budgets for sediment transfer on cultivated slopes.     

Soil erosion risk assessment using GIS and CORINE model: a case study from western Shiraz,Iran

This study employs the Coordination of Information on the Environment (CORINE) model with geographic information system to assess soil erosion risk for restoring and protecting areas within the Bonrod Zangane watershed, western Shiraz, Iran. Actual soil erosion risk was determined by combining two main parameters including potential soil erosion risk and vegetation cover. The potential soil erosion risk was generated by integrating soil erodibility, erosivity and slope parameters. Soil texture, depth and stoniness layers were overlaid to form a soil erodibility map. Modified Fournier index and Bagnouls–Gaussen aridity index were integrated to generate the erosivity layer. The slope classes also were generated from digital elevation model. In order to estimate vegetative land cover, the normalized difference vegetation index (NDVI) was used. The raster-based layers were then integrated to produce erosion risk map. The results showed that 34.7% of the study area has high and only 31.4% of the study area has low soil erosion risk. It is concluded that CORINE model can be used to delineate the soil erosion risk and also to discriminate the potential soil erosion risk areas.     

不同植被盖度下的黄土高原土壤侵蚀特征分析

利用地理信息系统(GIS)技术对黄土高原土壤侵蚀空间数据和植被盖度等级数据进行了空间叠加,研究不同盖度的植被对土壤侵蚀的影响。结果表明:植被盖度等级为1时,黄土高原土壤侵蚀全部为水蚀,占整个土壤侵蚀的100%;植被盖度等级为2时,土壤侵蚀主要以水蚀为主,占整个土壤侵蚀的95.61%;植被盖度等级为3、4、5时,土壤侵蚀仍主要以水蚀为主,分别占整个土壤侵蚀的74.90%、66.68%和58.19%。冻融侵蚀出现在植被盖度等级为4和5时,占整个土壤侵蚀的比例均不大。随着植被盖度的增加水蚀所占比重逐渐减小,而风蚀、水?风混合侵蚀和冻融侵蚀所占比重逐渐加大。植被盖度等级为5时,水蚀、风蚀和水-风混合侵蚀的土壤侵蚀指数均比其他植被盖度等级的土壤侵蚀指数大,分别为657.56、796.68和596.79,土壤侵蚀最严重。黄土高原植被盖度变化对土壤侵蚀状况影响显著。     

Tillage and crop management effects on soil erosion in central Croatia

Soil erosion continues to be a primary cause for soil degradation and the loss of soil quality throughout the world. Our objectives were to quantify soil erosion (referred to as erosional drift) and to assign erosion risk to six tillage and crop management treatments evaluated from 1995 to 1999 for a 5-year maize (Zea mays L.), soybean (Glycine hyspida L.), winter wheat (Triticum aestivum L.), oil-seed rape (Brassica napus var. oleifera L.), and spring barley (Hordeum vulgare L.) plus double-crop soybean rotation on Stagnic Luvisols in central Croatia. Standard black fallow (tilled, unsown, and without any vegetative cover) Universal Soil Loss Equation (USLE) plots were used to establish the erosion potential associated with the rainfall pattern for each year. Soil loss from the check plots was several times greater than the T value, which is estimated to be 10 t ha⁻¹ per year. During the 2 years when spring seeded maize or soybean were grown (1995 and 1996) erosion risk was extremely high, especially for treatments where tillage and planting (row direction) were up and down the slope. When autumn seeded winter wheat or oil-seed rape were grown (1996/1997 or 1997/1998), soil erosion was insignificant. Also, except when plowing and sowing were up and down slope, erosion loss for the spring barley plus double-crop soybean crops in 1999 was insignificant. With no-tillage, soil erosion from the maize and soybean crops was reduced 40 and 65% compared to plowing up and down slope, even though the planting direction was still up and down the slope. With the exception of maize in 1995, erosion losses were moderate to insignificant when plowing and planting were performed across the slope. We conclude that erosion risk can be used as a reliable indicator of sustainable land management and that using no-tillage or plowing and planting perpendicular to the predominant slope are effective soil conservation practices for this region.