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1.
In this paper, the Annualized Agricultural Non‐Point Source (AnnAGNPS) model has been used to estimate runoff, peak discharge and sediment load at the event scale in a Mediterranean watershed. The study area is the Carapelle torrent, Southern Italy (area = 506 km2), where continuous rainfall, streamflow and sediment load data are available. Nineteen flood events have been registered in the period 2007–2009 and were used for the application of the model. The aim of the paper is to evaluate the predictive accuracy of the model at the event scale, in a medium‐size watershed, given the specific conditions of the semi‐arid environments. A sensitivity analysis has been carried out to assign the correct parameterization: the mean normalized output variation of the most meaningful input parameters pointed out the influence of the curve number on runoff, peak discharge and sediment load predictions (values greater than 1); the MN Manning's roughness coefficient and K, C and P factors of the universal soil loss equation showed a moderate influence on sediment load simulations (values between 0·5 and 1). The selection of the Soil Conservation Service synthetic storm types has been based on the observed storm events analysis to improve the peak discharge simulations. The model prediction has proved to be good for runoff (R2 = 0·74, NSE = 0·75, W = 0·92) and peak discharge (R2 = 0·85, NSE = 0·70, W = 0·94), and satisfactory for sediment yield (R2 = 0·70, NSE = 0·63, W = 0·91). The relative error is lower for high events; this result is quite interesting in semi‐arid environments, where most of the annual sediment yield is concentrated in a few, severe events. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

2.
The catchments in the western Rift Valley escarpment of northern Ethiopia are highly responsive in terms of hydro‐geomorphic changes. With deforestation, dense gully and scar networks had developed by the 1980s on the escarpment between the towns of Alamata and Korem, transporting huge amounts of runoff and sediment down to the fertile and densely populated Raya Valley. To reverse this problem, catchment‐scale rehabilitation activities were initiated in the mid‐1980s. In this study, we examine the major hydro‐geomorphic response of streams after catchment rehabilitation. Scar networks in 20 adjacent catchments were mapped on Google Earth imagery of 2005, and their density was explained in terms of its corresponding Normalized Difference Vegetation Index and slope gradient. Soil and water conservation measures and vegetation recovery have reduced discharge and sediment flow which in turn resulted in various hydro‐geomorphic changes. In a multiple regression analysis, scar density was negatively related with Normalized Difference Vegetation Index and positively with average gradient of very steep slopes (r2 = 0·53, p < 0·01, n = 20). The size and amount of sediment supply to streams decreased, and various channel adjustments occurred. Notably, previously braided streams have changed to single thread streams, lateral bars have been stabilized and stream channels are narrowing and incising. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

3.
This study aims to demonstrate that the SWAT model can be used to predict discharge and sediment yield values in reservoir contributing catchments helping also to define the main factors that determine sedimentation rates in semi‐arid Mediterranean environments. This aim was achieved by comparing SWAT simulation results with water flows (over 29 years) and sediment deposition (over 47 years) volumes collected (by a campaign of bathymetric surveys) in a Sicilian reservoir. The mean monthly runoff coefficient calculated for the period 1980–2008 was 0·17. The mean sedimentation volume in the reservoir during the period 1963–2009 was 51,000 m3 year−1. Field surveys and collection of spatially distributed databases of soil, topography and climate were carried out in order to characterize the contributing catchment. The SWAT model was applied to simulate sediment volumes cumulated over group of years as well as water flow volumes reaching annual and monthly the reservoir. The performance of the hydrological and erosion components of the model was evaluated by a combination of both summary and difference statistical measures after a sensitivity analysis and a calibration/validation process. The model was able to simulate observed runoff volumes at both annual and monthly scale. The mean sedimentation volume simulated by SWAT during the whole period was 8·1% lower than the value obtained by the bathymetric measurements (equal to 72·103 Mg) with very good values of the efficiency coefficient (equal to 0·91). Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

4.
模拟降雨下坡面微地形量化及其与产流产沙的关系   总被引：9，自引：5，他引：9  
为揭示坡面微地形对土壤侵蚀过程的响应,该文通过人工模拟降雨试验,结合三维激光扫描仪技术,研究了不同雨强连续降雨条件下黄土坡面微地形变化特征及其与产流产沙的响应关系。结果表明所选取的5个常规地形因子(微坡度、地形起伏度、地表切割度、洼地蓄积量、地表粗糙度)对坡面侵蚀的响应表现出相似的趋势,即随着侵蚀的加剧,地形因子数值逐渐增大;场降雨后,地表粗糙度的增幅最小,分别是3%、8%、17%,对侵蚀的响应最弱,洼地蓄积量的增幅最大,分别增大11.82、18.86、83.33倍,对侵蚀的响应最强;同一雨强下随着连续降雨的进行,产流率稳定,1 mm/min雨强下输沙率基本稳定,1.5与2 mm/min下输沙率不断减小;2 mm/min雨强下输沙率和累积输沙量,远大于其他2个雨强处理;地形因子之间有很强的相关性,但能从不同侧面反映地形的信息,而且都与产流率和累积产沙量之间有较好的线性关系。研究可为进一步揭示黄土区坡面土壤侵蚀机理提供参考。  相似文献   

5.
Sediments deposited by (paleo) flash floods can hold valuable information on processes of environmental change, land degradation or desertification. In order to assess the suitability of flash flood deposits as proxies for land degradation, we monitored a representative gully segment in North Ethiopia (Ashenge catchment), investigated a sequence of alluvial debris fans downstream of this segment and dated a neighbouring subaquatic debris fan using short‐lived 210Pb isotope counting. During one rainy season (July–September 2014), we measured daily rainfall, peak discharge, bedload transport, suspended sediment load and sediment deposition rates. The data show that sediment deposition in the debris fans is significantly dependent on micro‐topography (net incision in micro‐channels) (p < 0·1) and position within the sequence (net incision farther away from the lake) (p < 0·05). As sediment transfer to the lake significantly depends on the balance between available water and sediment (ratio rainfall depth/bedload transport) (p < 0·05), we could reconstruct the hydro‐sedimentary evolution of the gully over the past half century and validate it with aerial photographs and semi‐structured interviews. The findings are consistent with the short‐lived isotope count results, indicating increased sediment supply from the 1970s onwards, when little amounts of clay were deposited in the lake (<5%), and a subrecent clear water effect that resulted in increased deposition rates of clay in the lacustrine debris fan. Overall, our analysis indicates that debris fan sediments can be used to estimate past environmental degradation rates, if the contemporary water and sediment behaviour is well understood. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

6.
Revegetation of road cuts and fills is intended to stabilize those drastically disturbed areas so that sediment is not transported to adjacent waterways. Sediment has resulted in water quality degradation, an extremely critical issue in the Lake Tahoe Basin. Many revegetation efforts in this semiarid, subalpine environment have resulted in low levels of plant cover, thus failing to meet project goals. Further, no adequate physical method of assessing project effectiveness has been developed, relative to runoff or sediment movement. This paper describes the use of a portable rainfall simulator (RS) to conduct a preliminary assessment of the effectiveness of a variety of erosion‐control treatments and treatment effects on hydrologic parameters and erosion. The particular goal of this paper is to determine whether the RS method can measure revegetation treatment effects on infiltration and erosion. The RS‐plot studies were used to determine slope, cover (mulch and vegetation) and surface roughness effects on infiltration, runoff and erosion rates at several roadcuts across the basin. A rainfall rate of ≈60 mm h−1, approximating the 100‐yr, 15‐min design storm, was applied over replicated 0·64 m2 plots in each treatment type and over bare‐soil plots for comparison. Simulated rainfall had a mean drop size of ≈2·1 mm and approximately 70% of ‘natural’ kinetic energy. Measured parameters included time to runoff, infiltration, runoff/infiltration rate, sediment discharge rate and average sediment concentration as well as analysis of total Kjeldahl nitrogen (TKN) and dissolved phosphorus (TDP) from filtered (0·45 μm) runoff samples. Runoff rates, sediment concentrations and yields were greater from volcanic soils as compared to that from granitic soils for nearly all cover conditions. For example, bare soil sediment yields from volcanic soils ranged from 2–12 as compared to 0·3–3 g m−2 mm−1 for granitic soils. Pine‐needle mulch cover treatments substantially reduced sediment yields from all plots. Plot microtopography or roughness and cross‐slope had no effect on sediment concentrations in runoff or sediment yield. RS measurements showed discernible differences in runoff, infiltration, and sediment yields between treatments. Runoff nutrient concentrations were not distinguishable from that in the rainwater used. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

7.
The effects of grazing and cultivation management on infiltration, runoff and sediment yield on storm basis were quantified for summer rangeland in the Matash mountains (Talesh Region), northern Iran. The infiltration experiments were made using double cylinder infiltrometer with five replicates within each study treatment. The runoff generation and sediment yield were measured using standard plots (1·83 m × 22·18 m) in three replications. The peak and the terminal instantaneous infiltration, and runoff and sediment rates were compared using independent and paired sample t‐test in two aforesaid treatments, respectively. The terminal and the peak instantaneous infiltration rates of 39·6 and 342·9 mm/h showed a respective significant increase (p < 0·001) of 32 and 39 per cent in cultivated areas compared to those in open grazing treatments. The results of runoff analysis also showed that there was a significant difference (p < 0·001) in runoff generation in two above‐mentioned areas. The runoff water was also found to be 5·63‐folds more in case of open grazing treatment in comparison with that generated by cultivated plots. A significant difference (p < 0·001) in sediment yield between two study treatments was also proved by the results obtained through sediment yield study. The soil loss in open grazing treatment was found to be 26·6 times more than of that occurred in cultivated plots. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

8.
Development plans are mainly responsible for population changes and the conversion of forest and rangelands into agricultural lands and human settlements. Qualitative and quantitative analysis of population and land use changes are necessary to assess the impacts of change on hydrological processes. However, such important issues have been less considered worldwide particularly in developing countries. Therefore, we selected the Shazand Watershed (1740 km2) because of rapid industrialization to track the effects of land use and population changes on streamflow and sediment yield. The data were collected from statistical yearbooks and satellite imageries from 1973 to 2008. All available measurements on discharge and suspended sediment concentration at the Pole doab hydrological station were also collected. The study was conducted for the whole period, as well as the pre‐1991 and post‐1991 as a basis for the economic development growth in the region. We found that the land use and population changes have occurred in the Shazand Watershed, especially in the vicinity of industrial zones. The results showed that the cities, industrial zones, roads, and bare lands quickly increased from 58 · 8 to 134 · 3 km2 during post‐1991. The flow durations, sediment rating curves and trend analyses indicated distinct variations in the relationship between streamflow and sediment and also caused changes within different periods. Based on the results, the mean annual flow and sediment yield in post industrialization (1991–2008) were respectively 0 · 84 and 1 · 19 times of those for pre‐industrialization period and the annual sediment yield increased from 25,000 to 29,850 Mg. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

9.
Grassed waterways (GWWs) transport sediment and nutrients from upland source areas to receiving waters. Watershed planners have a critical need to understand GWW sediment delivery to optimally target source area management practices. Better physically based tools are needed to estimate sediment delivery by GWWs. This study developed several distributed sediment delivery ratio (SDR) regressions for GWWs using the process‐based Water Erosion Prediction Project (WEPP) model to provide simple equations to estimate sediment delivery for planning applications. Water Erosion Prediction Project was calibrated and validated for runoff and sediment yield for large 30.2‐ha and smaller 5·7‐ha nested watersheds with terraces and a common GWW outlet. A crop rotation of corn, oat and alfalfa and fall tillage using chisel plow were used in the nested watersheds. A hypothetical management case without terraces using corn, oat and alfalfa rotation with chisel plow as fall tillage was also evaluated for the 5·7‐ha watershed and the GWW. The length, slope, Manning's roughness coefficient and infiltration rate for the GWW were varied and SDRs calculated for 30 representative (in terms of daily rainfall) days over a 20‐year period of simulated climate. Regressions were developed for the existing (terraced) and hypothetical (non‐terraced) management scenarios for early (April–July), late (August–October) and full (April–October) growing seasons. Equations developed for the non‐terrace watershed had higher R 2 values compared to the terraced watershed suggesting that channel and rainfall parameters were better able to explain the variation in SDR for the non‐terraced watershed. Manning's roughness coefficient was the most significant parameter for predicting SDR for both the terraced and non‐terraced watersheds. The equations developed here can be used to estimate SDRs for watersheds that are drained via GWWs having similar physical characteristics: slope (1–5%), Mannings's roughness coefficient (0·1–0·3), length (0·15–1 km) and infiltration rate (0·025–25 mm h−1). The SDRs can be used to estimate sediment yield, which is an essential element for making land management decisions but is rarely measured. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

10.
Changes in runoff and sediment loads are of great importance for the management of river basins and the implementation of soil and water conservation measures. This study compared the suspended sediment dynamics in the Huangfuchuan and Yanhe catchments on the Loess Plateau. Both annual runoff and sediment load displayed significant reductions from 1955 to 2012. The decreasing rates were −0·88 mm a−1 and −2·72 Mg ha−1 a−1 in the Huangfuchuan catchment, respectively, and ‐0.31 mm a−1 and −1·20 Mg ha−1 a−1 in the Yanhe catchment. A total of 183 and 195 events, respectively, were selected to assess the suspended sediment dynamics in both catchments during the periods of 1971–1989 and 2006–2012. The results showed a good linear relationship between the sediment yield and runoff depth in both catchments from 1971 to 1989 and a relatively worse relationship in the Yanhe catchment from 2006 to 2012. The magnitude and frequency of the hyper‐concentrated sediment flow obviously decreased in the 2000s compared with that between 1971 and 1989. A hysteresis analysis suggested that complex and counter‐clockwise loops were the dominant patterns. Various soil and water conservation measures (e.g., afforestation, grassing, terraces, and check dams) played a critical role in runoff and sediment load changes in both catchments. The two catchments showed obvious heterogeneities in runoff and sediment yield because of different lithologies, soil types, and vegetation. The results of this study provide valuable information on suspended sediment dynamics and could be used to improve soil erosion control measures on the Loess Plateau. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

11.
Soil erosion is a severe problem on China's Loess Plateau due to its fine‐grained soils and the increasing frequency of extreme rainfall events. Accordingly, this study used a 100‐year frequency rainstorm dataset to analyse sediment deposition and sources in a 27‐km2 catchment with a dam field area of 0·14 km2 based on the hypothesis that sediments were intercepted by the dam (before collapse) during the rainstorm event and deposited in the dam field. This study applied composite fingerprinting, which revealed the sediment source contributions and estimated sediment deposition. Sediment deposition (626·4 kg m−2) decreased linearly or exponentially with increasing distance from the dam. Composite fingerprints based on the optimal parameters revealed relative sediment contributions of 44·1% ± 25·5%, 37·7% ± 35·0%, 9·0% ± 11·4% and 9·2% ± 11·5% by bare ground, croplands, grassland and forests, respectively. The 5‐year cumulative sediment deposition from normal rainfall was 2·3 × 104 t less than the extreme rainstorm. Bare grounds and croplands were the dominant sediment sources following both the extreme rainstorm and normal erosive rainfall events but varied at different areas of the check‐dam. Erosion patterns and start times depended on land use type, thereby affecting sediment profiles in the dam field. Furthermore, severe erosion from bare ground that were all gully slopes and gully walls occurred throughout the rainfall, whereas grasslands and forest erosion occurred earlier and croplands later. Finally, extreme rainfall promoted mass wasting on slopes, gully slopes and gully walls, which are important in determining extreme rainstorm erosion pattern variation. This study aimed to reveal erosion pattern variation under extreme rainstorm events. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

12.
Runoff is the key factor to understand the land degradation causing high risk of soil erosion and can reduce the water available for human societies and ecosystems. The dynamics of runoff and suspended sediment transport are not completely understood. In this study, we examined the trends, breaking point and regime changes for the runoff and sediment load at different temporal scales using 50 years of continuous observational data from a highly erodible sub‐catchment with an area of 7,325 km2 in the Beiluo River basin on the Loess Plateau, China. At the annual scale, the runoff and sediment load declined significantly (p < 0·05) with decreasing rates of −0·23 mm y−1 and −164·9 Mg km−2 y−1, respectively. Abrupt changes in the runoff and sediment load series were detected between 1979 and 1999; thus, the data were divided into intervals of 1960–1979, 1980–1999 and 2000–2009. The flow duration curve analysis indicated increasing low‐flow values and decreasing daily runoff and sediment discharge peaks, which suggested that soil and water conservation measures reduced the volume of runoff and the sediment load. This led to a more uniform runoff regime. At the flood event scale, we investigated the relationship between runoff and the suspended sediment load based on 123 flood events, which showed clearly that the magnitude and frequency of hyper‐concentrated sediment flows decreased in 2000–2009 compared with 1960–1999. The annual erosive rainfall exhibited non‐significant changes throughout the entire study period. We conclude that soil and water conservation measures (e.g. afforestation, grassing, terraces and check dams) have played major roles in the changes in runoff and the sediment load in the Beiluo River catchment. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

13.
Unpaved roads play an important role in soil loss in small watersheds. In order to assess the impact of these unpaved roads in the Loess Plateau of China, runoff and sediment yields from road‐related sources must be quantified. Field rainfall simulation experiments were conducted under three slope gradients and five rainfall intensities on unpaved loess roads in a small watershed. Results showed that the runoff generation was very fast in loess road surface (time to runoff < 1 min) and produced a high runoff coefficient (mean value > 0·8). Soil loss rates were decreased as surface loose materials were washed away during a rainstorm. Rainfall intensity, initial soil moisture, and slope gradient are key factors to model surface runoff and sediment yield. Soil loss on loess road surface could be estimated by a linear function of stream power (R2 = 0·907). Four commonly interrill erosion models were evaluated and compared, and the interrill erodibility adopted in the Water Erosion Prediction Project model was determined as 1·34 × 106 (kg s m−4). A new equation taking into account different parameters like rainfall intensity, surface flow discharge, and slope gradient was established. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

14.
To date, the mechanical control of drifting sand is the main method used for the protection of the Qinghai‐Tibet Railway from damage. The thermal effect of sandy sediments which are held in place on the underlying permafrost is a key area of interest and the focus of this paper. A ground temperature investigation of the permafrost along the railway route was undertaken and results were related to the different mechanical control measures used to control moving sand which had resulted in varying sandy sediment thicknesses. The studies were conducted in the Hongliang River area of the Qinghai‐Tibet Plateau from June 2010 to September 2010 using thermistor sensors. The results showed that the permafrost ground temperature and its daily variation, as well as the thawing depth of the active layer, decreased after the setting‐up of sand movement controls which had resulted in the accumulation of thick sandy sediments within the outside fringe of sand‐control engineering, or a covering of thin sandy sediments within the inside trackside (fringe) of sand‐control engineering. Below the thick sandy sediment cover accumulated by sand‐blocking fences, the average maximum temperature decreased. Average temperature decreased and the average depth of seasonal thawing (average thinning) were 3·38°C, 0·54°C and 0·48 m, respectively. Below the thin sand sediment cover accumulated by the checkerboard sand barriers, the values for the same parameters were 1·02°C, 0·21°C and 0·5 m, respectively. This study found that the mechanical control of sand does not only protect the railway from obstruction, but also facilitates permafrost stability, which in turn can help promote safety in railway operations. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

15.
Soil erosion is a serious problem in the Loess Plateau of China, and assessment of soil erosion at large watershed scale is urgently need. This study used RUSLE and GIS to assess soil loss in the Yanhe watershed. All factors used in the RUSLE were calculated for the watershed using local data. RUSLE‐factor maps were made. The mean values of the R‐factor, K‐factor, LS‐factor, C‐factor and P‐factor were 970 209 MJ km−2 h−1 a−1, 0·0195 Mg h MJ−1 mm−1, 10·27, 0·33359 and 0·2135 respectively. The mean value of the annual average soil loss was found to be 14 458 Mg km−2 per year, and the soil loss rate in most areas was between 5000 and 20 000 Mg km−2 per year. There is more erosion in the centre and southeast than in the northwest of Yanhe watershed. Because of the limitations of the RUSLE and spatial heterogeneity, more work should be done on the RUSLE‐factor accuracy, scale effects, etc. Furthermore, it is necessary to apply some physical models in the future, to identify the transport and deposition processes of sediment at a large scale. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

16.
The flow–sediment relationship is important to understand the soil erosion and land degradation processes in severe eroded areas. This study researches on variations of streamflow, sediment load, and flow–sediment relationship on multi‐temporal scales (annual, flood season and, monthly scales) in a highly erodible catchment of Chinese Loess Plateau. The results demonstrated that the streamflow, sediment load, sediment concentration, runoff coefficient, and sediment coefficient all experienced evident reductions, and the decrease in the middle and downstream stations was more significant compared with the upstream stations. The land use changes and implementation of soil and water conservation measures played major role for the streamflow and sediment load reductions with respect to precipitation change, and the runoff coefficient and sediment coefficient linearly decreased with the percentage of conservation measure area. The runoff‐sediment yield relationship on annual, flood season, and monthly scales could be generally characterized by the linear function, and the slopes during the post‐change period was lower than those during the pre‐change period of sediment load. The sediment concentration–streamflow discharge relationship represented consistent form over the entire study period, and the logarithmic function was appropriate to describe the relationships on the three timescales. The decrease of sediment concentration contributed greatest (60·7%) to sediment reduction compared with runoff productivity of rainfall (30·2%) and precipitation (9·1%). Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

17.
The impact of the topographical position on soil properties was evaluated in an olive grove with traditional tillage. Three topographical positions: summit, backslope and toeslope were chosen for evaluation. The soil samples were taken from four soil sections of 0·25 m (0–1 m). The soil organic carbon (SOC) and N content increased along the downslope direction (5·5, 6·5 and 7·1 g C kg−1 and 0·3, 0·8 and 0·9 g N kg−1 in the surface layer in the summit, backslope and toeslope respectively) as well as SOC and N stocks, considering the two first soil sections. In addition, there was movement of the most erodible textural fraction (silt). However, the total SOC stock (refer to 1 m of depth) did not vary with respect to the topographical position, but the total N stock (refer to 1 m of depth) varied significantly. These increases were due to erosion processes that occur along the toposequence, leading to organic matter transfers from the summit to the toeslope. All the stratification ratios calculated were lower than 2, indicating the low quality of the soils. Therefore, alternative management techniques that avoid soil erosion must be considered in olive grove in order to increase the soil quality and fertility. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

18.
The sediment budget is a key concept and tool for characterizing the mobilization, transfer and storage of fine sediment within a catchment. Caesium‐137 measurements can provide valuable information on gross and net erosion rates associated with sheet and rill erosion that can be used to establish the slope component of a catchment sediment budget. However, there is a need to validate the use of 137Cs measurements for this purpose, because their reliability has sometimes been questioned. The study reported focuses on a small (3·04 ha) steepland (mean slope 37%) catchment in Southern Italy. It exploits the availability of information on the medium‐term sediment output from the catchment provided by the construction of a reservoir at its outlet in 1978 and the existence of estimates of soil redistribution rates derived from 137Cs measurements made on 68 replicate soil cores collected from the slopes of a substantial proportion of the catchment in 2001, to validate the use of 137Cs measurements to construct the slope component of the catchment sediment budget. An additional 50 replicate soil cores were collected from the catchment slopes for 137Cs analysis, to complement the data already available. Nine cores collected from the area occupied by the reservoir were used to estimate the mean annual sediment input to the reservoir. In the absence of evidence that the poorly developed channel system in the catchment was either a significant sediment source or sink, it was possible to directly compare the estimate of net soil loss from the catchment slopes (7·33 Mg ha−1 y−1) with the estimate of sediment output from the catchment provided by the reservoir deposits (7·52 Mg ha−1 y−1). Taking account of the uncertainties involved, the close agreement of the two values is seen as providing a convincing validation of the use of 137Cs measurements to both estimate soil redistribution rates and as a basis for constructing the slope component of the sediment budget of a small catchment. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

19.
Understanding spatial and temporal patterns in land susceptibility to wind erosion is essential to design effective management strategies to control land degradation. The knowledge about the land surface susceptible to wind erosion in European contexts shows significant gaps. The lack of researches, particularly at the landscape to regional scales, prevents national and European institutions from taking actions aimed at an effective mitigating of land degradation. This study provides a preliminary pan‐European assessment that delineates the spatial patterns of land susceptibility to wind erosion and lays the groundwork for future modelling activities. An Index of Land Susceptibility to Wind Erosion (ILSWE) was created by combining spatiotemporal variations of the most influential wind erosion factors (i.e. climatic erosivity, soil erodibility, vegetation cover and landscape roughness). The sensitivity of each input factor was ranked according to fuzzy logic techniques. State‐of‐the‐art findings within the literature on soil erodibility and land susceptibility were used to evaluate the outcomes of the proposed modelling activity. Results show that the approach is suitable for integrating wind erosion information and environmental factors. Within the 34 European countries under investigation, moderate and high levels of land susceptibility to wind erosion were predicted, ranging from 25·8 to 13·0 M ha, respectively (corresponding to 5·3 and 2·9% of total area). New insights into the geography of wind erosion susceptibility in Europe were obtained and provide a solid basis for further investigations into the spatial variability and susceptibility of land to wind erosion across Europe. © 2014 The Authors. Land Degradation and Development published by John Wiley & Sons, Ltd.  相似文献   

20.
Rill is a major type of erosion on upland slopes. Continuous rainfall is commonly used in laboratory studies on rill erosion despite the fact the rainfall was often discontinuous in the field; this is particularly true in the Chinese Loess Plateau. This study compares rill erosion under continuous and intermittent rainfalls by using laboratory experiments. The experiments include two rainfall‐intensity treatments (90 and 120 mm h−1) and two rainfall‐pattern treatments (continuous and intermittent). The results indicate that rill formation had a significant effect on runoff and sediment concentration. For continuous and intermittent rainfall at the rainfall intensity of 90 mm h−1, the mean sediment concentrations were 1·91 and 1·73 times after rill initiation than those before rill initiation, respectively, and the rill erosion accounted for 75·5% and 77·7% of runoff duration, respectively. For continuous and intermittent rainfall at the rainfall intensity of 120 mm h−1, the mean sediment concentrations after rill initiation were 1·38 and 1·32 times that those before rill initiation, respectively, and the rill erosion represented 88·7% and 78·8% of the total runoff duration, respectively. We observed sediment sorting under all treatments; however, the low rainfall intensity boosted but the high rainfall intensity lowered the clay fraction; in contrast, the sorting remained roughly the same between the rainfall‐pattern treatments. The runoff velocity also affected the sediment sorting. Our empirical results indicated the important significance of the rainfall intermittence in predicting rill erosion. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

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