Soil loss rates due to piping erosion

Compared with surface soil erosion by water, subsurface erosion (piping) is generally less studied and harder to quantify. However, wherever piping occurs, it is often a significant or even the main sediment source. In this study, the significance of soil loss due to piping is demonstrated through an estimation of soil volume lost from pipes and pipe collapses (n = 560) in 137 parcels under pasture on loess‐derived soils in a temperate humid climate (Belgium). Assuming a period of 5 to 10 years for pipe collapse to occur, mean soil loss rates of 2.3 and 4.6 t ha^?1 yr^?1 are obtained, which are at least one order of magnitude higher than surface erosion rates (0.01–0.29 t ha^?1 yr^?1) by sheet and rill erosion under a similar land use. The results obtained for the study area in the Flemish Ardennes correspond well to other measurements in temperate environments; they are, however, considerably smaller than soil loss rates due to subsurface erosion in semi‐arid environments. Although local slope gradient and drainage area largely control the location of collapsed pipes in the study area, these topographic parameters do not explain differences in eroded volumes by piping. Hence, incorporation of subsurface erosion in erosion models is not straightforward. Copyright © 2011 John Wiley & Sons, Ltd.     

Piping dynamics in mid‐altitude mountains under a temperate climate: Bieszczady Mountains,eastern Carpathians

Piping has been recognized as an important geomorphic, soil erosion and hydrologic process. It seems that it is far more widespread than it has often been supposed. However, our knowledge about piping dynamics and its quantification currently relies on a limited number of data for mainly loess‐derived areas and marl badlands. Therefore, this research aimed to recognize piping dynamics in mid‐altitude mountains under a temperate climate, where piping occurs in Cambisols, not previously considered as piping‐prone soils. It has been expressed by the estimation of erosion rates due to piping and elongation of pipes in the Bere?nica Wy?na catchment in the Bieszczady Mountains, eastern Carpathians (305 ha, 188 collapsed pipes). The research was based on the monitoring of selected piping systems (1971–1974, 2013–2016). Changes in soil loss vary significantly between different years (up to 27.36 t ha^?1 yr^?1), as well as between the mean short‐term erosion rate (up to 13.10 t ha^?1 yr^?1), and the long‐term (45 years) mean of 1.34 t ha^?1 yr^?1. The elongation of pipes also differs, from no changes to 36 m during one year. The mean total soil loss is 48.8 t ha^?1 in plots, whereas in the whole studied catchment it is 2.0 t ha^?1. Hence, piping is both spatially and temporally dependent. The magnitude of piping in the study area is at least three orders of magnitude higher than surface erosion rates (i.e. sheet and rill erosion) under similar land use (grasslands), and it is comparable to the magnitude of surface soil erosion on arable lands. It means that piping constitutes a significant environmental problem and, wherever it occurs, it is an important, or even the main, sediment source. Copyright © 2017 John Wiley & Sons, Ltd.     

Assessment of sediment yield in a small karst catchment by using 137Cs tracer technique

There is very thin soil layer in karst rocky desertification areas in Southwest China,sediment deposition and sediment yield in the karst area affects the development of vegetation greatly.In the present study,the ¹³⁷Cs technique was used to assess the rate of sediment deposition and sediment yield in a small karst catchment.The ¹³⁷Cs inventory within the depression varied between 800 m^-2 and 2,200 Bq m^-2,with the mean value of 1,500.1 Bq m^-2.The ¹³⁷Cs reference inventory at a nearby reference site was 805.9 Bq m^-2.It could be inferred to that sediment deposition had occurred in the catchment.The mean depth of sediments deposition in the depression was 6 cm and the deposition rate was approximately 0.13 cm yr^-1.The analysis of the topographic characteristics of the catchment revealed that the sediment deposition occurred mainly at the lower part of the small catchment.Although,there was a sinkhole in the depression,little sediment had drained out with runoff through the sinkhole,because the local people built ridges around the sinkholes for storing water.According to this,sediment yield rate in the small catchment was estimated to be approximately 19.25 to 27.5 t km^-2 yr^-1,and the extremely low sediment yield was maybe the main obstacle to vegetation restoration in karst rocky desertification areas.     

Estimation of soil erosion in the Xihanshui River Basin by using 137Cs technique

The Cesium-137 technique was used to estimate soil erosion in the Xihanshui River Basin.More than 100 samples were taken from 10 sites and 20 hillslopes with a 10cm diameter hand-operated core driller.Each sample was 60 cm long.The ¹³⁷Cs activity was analyzed by gamma spectrometry.The simplified mass balance model and the profile distribution model were used to calculate soil erosion and deposition rate.The local ¹³⁷Cs reference ranged from 1,600 to 2,402 Bq m^-2.The data shows an exponential decrease of mass concentration and amount with depth in an undisturbed soil profile.Soil erosion in the river basin is moderate or severe on cultivated land with annual erosion rates of 2,000-6,000 t km^-2yr^-1.In general,very severe or severe soil erosion occurred at the upper slope sections,moderate or severe soil erosion at the middle section,and moderate or slight soil erosion at the lower slope sections.On the slopes with natural vegetation,consisting of herbaceous and wood species,the erosion rate is much lower or not detectable.On the lower section of slopes with well-developed vegetation however,there was no soil loss,instead deposition occurred at a rate of more than 300 t km^-2 yr^-1.The slope gradient and vegetation cover affected soil erosion and deposition rates.In general,the rate of soil erosion was proportional to the slope gradient and inversely proportional to the degree of vegetative cover.     

Hillslope and point based soil erosion – an evaluation of a Landscape Evolution Model

Excessive soil erosion and deposition is recognised as a significant land degradation issue. Quantifying soil erosion and deposition is a non-trivial task. One of these methods has been the mathematical modelling of soil erosion and deposition patterns and the processes that drive them. Here we examine the capability of a landscape evolution model to predict both soil erosion rate and pattern of erosion and deposition. This numerical model (SIBERIA) uses a Digital Elevation Model (DEM) to represent the landscape and calculates erosion and deposition at each grid point in the DEM. To assess field soil redistribution rates (SRR) and patterns the distribution of the environmental tracer ¹³⁷Cs has been analysed. Net hill slope SRR predicted by SIBERIA (a soil loss rate of 1.7 to 4.3 t ha^-1 yr^-1) were found to be in good agreement with ¹³⁷Cs based estimates (2.1 – 3.4 t ha^-1 yr^-1) providing confidence in the predictive ability of the model at the hillslope scale. However some differences in predicted erosion/deposition patterns were noted due to historical changes in landscape form (i.e. the addition of a contour bank) and possible causes discussed, as is the finding that soil erosion rates are an order of magnitude higher than likely soil production rates. The finding that SIBERIA can approximate independently quantified erosion and deposition patterns and rates is encouraging, providing confidence in the employment of DEM based models to quantify hillslope erosion rates and demonstrating the potential to upscale for the prediction of whole catchment erosion and deposition. The findings of this study suggest that LEMs can be a reliable alternative to complex and time consuming methods such as that using environmental tracers for the determination of erosion rates. The model and approach demonstrates a new approach to assessing soil erosion that can be employed elsewhere. © 2018 John Wiley & Sons, Ltd.     

Contribution of intercepted subsurface flow to road runoff and sediment transport in a logging‐disturbed tropical catchment

Hydrological and sediment fluxes were monitored for a 1 yr period in a tropical headwater catchment where a 3 yr old logging road caused substantial Hortonian overland flow (HOF) and intercepted subsurface flow (ISSF). On a 51·5 m road section, ISSF became an increasingly important component of total road runoff, up to more than 90% for large storms. The proportion of ISSF contributed by road cuts along more or less planar slopes compared with ISSF from a zero‐order basin (convergent slopes) truncated by the road declined with increasing rainfall. During the monitored storms that generated ISSF along the road, on average, 28% of sediment export and 79% of runoff from the road section were directly attributable to ISSF. Estimates of total sediment export from the road surface (170 t ha^?1 yr^?1) and suspended sediment export from the logging‐disturbed catchment (4 t ha^?1 yr^?1) were exceptionally high despite 3 yr of recovery. ISSF caused not only additional road‐generated sediment export, but also exacerbated HOF‐driven erosion by creating a poor foundation for vegetation recovery on the road surface. Copyright © 2007 John Wiley & Sons, Ltd.     

Erosion rates in the southern oregon coast range: Evidence for an equilibrium between hillslope erosion and sediment yield

The relationship of hillslope erosion rates and sediment yield is often poorly defined because of short periods of measurement and inherent spatial and temporal variability in erosion processes. In landscapes containing hillslopes crenulated by alternating topographic noses and hollows, estimates of local hillslope erosion rates averaged over long time periods can be obtained by analysing colluvial deposits in the hollows. Hollows act as local traps for a portion of the colluvium transported down hillslopes, and erosion rates can be calculated using the age and size of the deposits and the size of the contributing source area. Analysis of colluvial deposits in nine Oregon Coast Range hollows has yielded average colluvial transport rates into the hollows of about 35cm³cm^?1yr^?1 and average bedrock lowering rates of about 0.07 mm yr^?1 for the last 4000 to 15000 yr. These rates are consistent with maximum bedrock exfoliation rates of about 0.09 mm yr^?1 calculated from six of the hollows, supporting the interpretation that exfoliation rates limit erosion rates on these slopes. Sediment yield measurements from nine Coast Range streams provide similar basin-wide denudation rates of between 0.05 and 0.08mm yr^?1, suggesting an approximate steady-state between sediment production on hillslopes and sediment yield. In addition, modern sediment yields are similar in basins varying in size from 1 to 1500 km², suggesting that erosion rates are spatially uniform and providing additional evidence for an approximate equilibrium in the landscape.     

Rainfall variability and hydrological and erosive response of an olive tree microcatchment under no‐tillage with a spontaneous grass cover in Spain

Most studies on runoff and soil loss from olive orchards were performed on plots, despite the fact that measurements that examine a range of erosive processes on different scales are essential to evaluate the suitability of the use and soil management of this type of land. The main environmental limitations of much of the land used for olive orchards in the Mediterranean are the steep slopes and the shallow soil depth – and this was the case in the study area. Soil erosion and runoff over two hydrological years (2005–2006 and 2006–2007) were monitored in an olive orchard microcatchment of 6·1 ha under no‐tillage with spontaneous grass in order to evaluate its hydrological and erosive behaviour. Moreover, soil parameters such as organic matter (%OM), bulk density (BD) and hydraulic saturated conductivity (Ks) were also examined in the microcatchment to describe management effects on hydrological balance and on erosive processes. In the study period, the results showed runoff coefficients of 6·0% in the first year and 0·9% in the second. The differences respond to the impact of two or three yearly maximum events which were decisive in the annual balances. On the event scale, although maximum rainfall intensity values had a big influence on peak flows and runoff, its importance on mean sediment concentrations and sediment discharges was difficult to interpret due to the likely control of grass cover on volume runoff and on soil protection. In the case of annual soil erosion, they were measured as 1·0 Mg ha^?1 yr^?1 and 0·3 Mg ha^?1 yr^?1. Both are lower than the tolerance values evaluated in Andalusia (Spain). These results support the implementation of no‐tillage with spontaneous grass cover for sloping land, although the reduced infiltration conditions determined by Ks in the first horizon suggest grass should be allowed to grow not only in spring but also in autumn. In addition, specific measurements to control gullies, which have formed in the terraced area in the catchment, should be included since it is expected that they could be the main sources of sediments. Copyright © 2010 John Wiley & Sons, Ltd.     

Dynamics of soil erosion rates and controlling factors in the Northern Ethiopian Highlands – towards a sediment budget

This paper analyses the factors that control rates and extent of soil erosion processes in the 199 ha May Zegzeg catchment near Hagere Selam in the Tigray Highlands (Northern Ethiopia). This catchment, characterized by high elevations (2100–2650 m a.s.l.) and a subhorizontal structural relief, is typical for the Northern Ethiopian Highlands. Soil loss rates due to various erosion processes, as well as sediment yield rates and rates of sediment deposition within the catchment (essentially induced by recent soil conservation activities), were measured using a range of geomorphological methods. The area‐weighted average rate of soil erosion by water in the catchment, measured over four years (1998–2001), is 14·8 t ha^?1 y^?1, which accounts for 98% of the change in potential energy of the landscape. Considering these soil loss rates by water, 28% is due to gully erosion. Other geomorphic processes, such as tillage erosion and rock fragment displacement by gravity and livestock trampling, are also important, either within certain land units, or for their impact on agricultural productivity. Estimated mean sediment deposition rate within the catchment equals 9·2 t ha^?1 y^?1. Calculated sediment yield (5·6 t ha^?1 y^?1) is similar to sediment yield measured in nearby catchments. Seventy‐four percent of total soil loss by sheet and rill erosion is trapped in exclosures and behind stone bunds. The anthropogenic factor is dominant in controlling present‐day erosion processes in the Northern Ethiopian Highlands. Human activities have led to an overall increase in erosion process intensities, but, through targeted interventions, rural society is now well on the way to control and reverse the degradation processes, as can be demonstrated through the sediment budget. Copyright © 2007 John Wiley & Sons, Ltd.     

Modelling catchment‐scale erosion patterns in the East African Highlands

Prompt location of areas exposed to high erosion is of the utmost importance for soil and water conservation planning. Erosion models can be useful tools to locate sources of sediment and areas of deposition within a catchment, but the reliability of model predictions of spatial patterns of erosion at catchment scale has seldom been validated against observations. This study aimed to evaluate the performance of a simple empirical model (Morgan, Morgan and Finney model, MMF) in predicting spatial patterns of erosion at two small catchments in the East African Highlands: Kwalei (Tanzania) and Gikuuri (Kenya). Erosion maps predicted by the MMF model were compared with erosion maps obtained by direct survey. In Kwalei, erosion features were especially frequent in fields of annual crops. In Gikuuri, slope was the critical erosion factor, with estimated erosion rates >10 kg m^?2 a^?1 on slopes >18 per cent. Predicted erosion rates were mainly transport‐limited and ranged from <0·01 to 13·50 kg m^?2 a^?1 in Kwalei and 9·29 kg m^?2 a^?1 in Gikuuri. The performance of the MMF model in predicting the spatial patterns of erosion was acceptable in Kwalei, but poor in Gikuuri. However, by excluding the elements at the valley bottoms in Gikuuri Catchment, the performance of the model improved dramatically. The spatial pattern of erosion predicted by the MMF model was driven by the accumulation of surface runoff, which did not consider the possibility of re‐infiltration along the slope. As a result, the MMF erosion patterns predicted by the model increased invariably from the ridges to the valley bottoms, hampering the model suitability for locating areas subjected to high and very high erosion. It is concluded that the model predictions could be substantially improved by introducing a more realistic hydrological component for the prediction of surface runoff along the hill‐slope. Copyright © 2005 John Wiley & Sons, Ltd.     

Orders of magnitude increase in soil erosion associated with land use change from native to cultivated vegetation in a Brazilian savannah environment

The Brazilian savanna (cerrado) is a large and important economic and environmental region that is experiencing significant loss of its natural landscapes due to pressures of food and energy production, which in turn has caused large increases in soil erosion. However the magnitude of the soil erosion increases in this region is not well understood, in part because scientific studies of surface runoff and soil erosion are scarce or nonexistent in the cerrado as well as in other savannahs of the world. To understand the effects of deforestation we assessed natural rainfall‐driven rates of runoff and soil erosion on an undisturbed tropical woodland classified as ‘cerrado sensu stricto denso’ and bare soil. Results were evaluated and quantified in the context of the cover and management factor (C‐factor) of the Universal Soil Loss Equation (USLE). Replicated data on precipitation, runoff, and soil loss on plots (5 × 20 m) under undisturbed cerrado and bare soil were collected for 77 erosive storms that occurred over 3 years (2012 through 2014). C‐factor was computed annually using values of rainfall erosivity and soil loss rate. We found an average runoff coefficient of ~20% for the plots under bare soil and less than 1% under undisturbed cerrado. The mean annual soil losses in the plots under bare soil and cerrado were 12.4 t ha^‐1 yr^‐1 and 0.1 t ha^‐1 yr^‐1, respectively. The erosivity‐weighted C‐factor for the undisturbed cerrado was 0.013. Surface runoff, soil loss and C‐factor were greatest in the summer and fall. Our results suggest that shifts in land use from the native to cultivated vegetation result in orders of magnitude increases in soil loss rates. These results provide benchmark values that will be useful to evaluate past and future land use changes using soil erosion models and have significance for undisturbed savanna regions worldwide. Copyright © 2015 John Wiley & Sons, Ltd.     

Caesium-137 estimates of erosion in agricultural areas

Sediment redistribution within near-level agricultural fields in the Gray Wooded soil zone of Saskatchewan was studied using the artificial environmental tracer caesium-137 (¹³⁷Cs). the objective of this study was to estimate erosion rates caused by wind erosion, and land clearing techniques (i.e. bulldozing). Net rates of erosion and deposition were quantified over the past 30 years on three fields. Wind erosion was estimated to be approximately 1.0 t ha^?1 y^?1 on a near-level field, with 50 per cent of the sampling sites having erosion rates in excess of soil formation. Bulldozing produced median net sediment flux values of between 40 and 90 t ha^?1 y^?1. in addition, between 65 and 85 per cent of the sampling sites had erosion rates in excess of the maximum tolerable limit (i.e. 11.0 t ha^?1 y^?1). These results indicate significant accelerated erosion results from land clearing techniques used in central Saskatchewan. Bulldozing of the fields removed the LFH-horizon and exposed the underlying mineral horizon. Bulk densitites of the 0 to 15 cm layer in the cleared fields were 27 to 55 per cent greater than the comparable depth increment within the undisturbed forest site. Organic carbon concentrations within the 1930s, 1979, and 1987 fields were decreased by 47, 42, and 37 per cent, respectively following cultivation and bulldozing. Decreases in total nitrogen for the cultivated fields ranged from 33 to 38 per cent.     

Rill erosion along the thalweg of a hillslope hollow: A case study from the cotswold hills,Central England

Rill erosion is an important erosional form on agricultural soils in England, causing large losses of soil, particularly on cultivated slopes. This paper describes a rill system that developed in a small agricultural catchment in north Oxfordshire during the winter of 1992–93. The rill system comprised two components: a system of ‘feeder rills’ along the valley-side slopes, which were the result of flow concentration and erosion along wheelings, and a thalweg rill, which formed along a dry valley bottom as a result of surface runoff concentration from the feeder rills. Total volumetric soil loss from the rill system was 32·28 m³, equivalent to 3·01 m³, ha^?1 for the rill catchment area, or 3·91 t ha^?1. Mean discharge for the thalweg rill and feeder rills, calculated during a storm event, was 31·101s^?1 and 1·171s^?1, respectively. All flows were fully turbulent and supercritical. We emphasize the need for a spatially distributed approach to the study of runoff and erosion at the catchment scale.     

Fire effects on rangeland hydrology and erosion in a steep sagebrush‐dominated landscape

Post‐fire runoff and erosion from wildlands has been well researched, but few studies have researched the degree of control exerted by fire on rangeland hydrology and erosion processes. Furthermore, the spatial continuity and temporal persistence of wildfire impacts on rangeland hydrology and erosion are not well understood. Small‐plot rainfall and concentrated flow simulations were applied to unburned and severely burned hillslopes to determine the spatial continuity and persistence of fire‐induced impacts on runoff and erosion by interrill and rill processes on steep sagebrush‐dominated sites. Runoff and erosion were measured immediately following and each of 3 years post‐wildfire. Spatial and temporal variability in post‐fire hydrologic and erosional responses were compared with runoff and erosion measured under unburned conditions. Results from interrill simulations indicate fire‐induced impacts were predominantly on coppice microsites and that fire influenced interrill sediment yield more than runoff. Interrill runoff was nearly unchanged by burning, but 3‐year cumulative interrill sediment yield on burned hillslopes (50 g m^?2) was twice that of unburned hillslopes (25 g m^?2). The greatest impact of fire was on the dynamics of runoff once overland flow began. Reduced ground cover on burned hillslopes allowed overland flow to concentrate into rills. The 3‐year cumulative runoff from concentrated flow simulations on burned hillslopes (298 l) was nearly 20 times that measured on unburned hillslopes (16 l). The 3‐year cumulative sediment yield from concentrated flow on burned and unburned hillslopes was 20 400 g m^?2 and 6 g m^?2 respectively. Fire effects on runoff generation and sediment were greatly reduced, but remained, 3 years post‐fire. The results indicate that the impacts of fire on runoff and erosion from severely burned steep sagebrush landscapes vary significantly by microsite and process, exhibiting seasonal fluctuation in degree, and that fire‐induced increases in runoff and erosion may require more than 3 years to return to background levels. Published in 2008 by John Wiley & Sons, Ltd.     

Assessment of long‐term Holocene soil erosion rates in Polish loess areas using sedimentary archives from closed depressions

Soil erosion is a particularly important problem in the loess areas of Central Europe. Numerous studies of past and present soil erosion based on colluvial sediments have so far been conducted. The main problem is the fact that colluvia usually do not represent the complete sedimentation record. Closed depressions (CDs) collect all colluvial sediments from their catchment, therefore, constitute sediment stores enabling the calculation of soil erosion rates. Colluvial sediments and fossil soils, infilling four CDs in the Polish loess belt, were OSL and C‐14 dated. Human settlements near the studied CDs were analyzed. Phases of soil erosion and colluviation from the Neolithic (5400–2900 bc ), from the Middle Bronze Age to the Early Iron Age (1600–0 bc ), and from the Early Middle Ages to Modern Times (500 AD until today) were documented within the CDs studied. Phases of low soil erosion rate and pedogenesis occurred from the Late Vistulian to the Early Neolithic and from the Iron Age to Early Middle Ages. This study reveals that these phases are not synchronous with the soil erosion phases in Central Europe, as the latter mainly occurred in the Bronze Age, Roman Period and Middle Ages. The obtained soil erosion rates were compared with erosion rates in different areas of Central Europe. This study indicates that in loess regions with long‐term agricultural land use, mean erosion rates (i.e. 3.7–5.9 t ha^‐1 yr^‐1) from the Middle Ages to Modern Times were ten times higher than during the entire prehistoric period (0.39–0.67 t ha^‐1 yr^‐1). The mean soil erosion rates for forested CDs was 0.24–0.74 t ha^‐1 yr^‐1. Soil erosion phases are most probably caused by human activities (i.e. land use change) but the early Holocene erosion phase (7.96 +/‐ 0.67 kyr) could have been induced by a climatic fluctuation (e.g. a 8.2 kyr Bond event). Copyright © 2018 John Wiley & Sons, Ltd.     

Mesoscalic estimation of nitrogen discharge via drainage systems

A complex approach has been developed for estimating mesoscalic nitrogen discharges via drainage systems using spatial information about land use, drainage areas, nitrogen balances and soil and site characteristics. Determining the total drainage area involves certain difficulties for larger areas, as on the one hand, the available databases are incomplete, and on the other hand the localisation and digitalisation of large subsurface drainage areas is a very time-consuming process. Knowledge of the history and causes of drainage systems in landscapes is required. To solve this problem a method has been developed to calculate the drainage areas for large catchments. In order to obtain a complete data set of subsurface drainage areas, representative areas were selected to enable the proportion of subsurface drainage area to be determined for various soil and site characteristics. These proportions were extrapolated to the entire area and the approach tested in the Mulde River Catchment Area in Germany.The rate of drained arable land is about 25.2% of the total area, which can be broken down into grassland (19.0%) and arable land (27.4%). The results differ for sandy soils with up to 8% drained areas and 57.8% for stagnant soils. This shows that the proportion of drained land is highly dependent on the nature of the soil in the catchment area, which has profound implications for approaches to nitrogen modelling.Average nitrogen discharge for the whole catchment area via drainage water was 33 kg ha⁻¹ yr⁻¹ in the 1980s and 10 kg ha⁻¹ yr⁻¹ in the 1990s. The nitrogen discharge varies from one soil type to another: in regions with sandy substrate (11,900 ha) discharge was 34 kg ha⁻¹ yr⁻¹ in the 1980s (14 kg ha⁻¹ yr⁻¹ in the 1990s), while in areas with loess lessivé soils (89,200 ha) it was about 26 kg ha⁻¹ yr⁻¹ in the 1980s (9 kg ha⁻¹ yr⁻¹ in the 1990s). The reduction can be explained by the complete change in farming strategy since the demise of the former German Democratic Republic (GDR).The approach shown is well suited to future model approaches on a regional scale. By creating and integrating new data sets derived from modern GIS operations the approach reduces the uncertainty of water and nitrogen modelling. This gives us a better understanding of nitrogen discharges into surface and groundwater and temporal discharge dynamics. The discharge data are highly valuable to predict environmental protection measurements for streams, lakes, coastal waters and groundwaters.     

Developing a sediment budget for a small drainage basin in Australia

A sediment budget was developed for the 1.7 km² Maluna Creek drainage basin located in the Hunter Valley, New South Wales, Australia, for the period 1971-86. the impact of viticulture, which commenced at Maluna in 1971, was studied using erosion plots, with caesium-137 as an indicator of both soil erosion and sedimentation. Two methods were used to estimate vineyard soil losses from caesium-137 measurements. Sediment output from the catchment was measured for three years, and extrapolated from readings taken at a nearby long-term stream flow gauging station for the remaining 13 years. Relative amounts of soil loss from forest (60 per cent basin area), grazing land (30 per cent) and vineyards (10 per cent) were calculated. Soil losses by rain splash detachment were ten times greater from bare/cultivated sufaces than from the forest. Erosion plots of area 2 m² showed no significant differences in soil loss between forest and grassland but, under bare soil, losses were 100 times greater. the ¹³⁷Cs method was employed to calculate net soil loss from all vineyard blocks using both a previously established calibration curve and a proportional model. the latter method gave estimates of soil loss which were 3-9 times greater than by the calibration curve, and indicated that average soil losses from the vineyard were equivalent to 62 t ha^?1 y^?1 (1971-86). It was estimated that the forest contributed 1-8 per cent, the grazing land 1.6 per cent, and the vineyard 96.6 per cent of the total soil loss during that period. Sediment storages within the fluvial system adjacent to the vineyard ws 9460 t for the period, whereas sediment output was equivalent to 215 t km^?1 y^?1. Independent measurements of soil erosion, storage, and output showed that 56 per cent of the eroded sediment remained in the catchment, and 34 per cent was transported out by Maluna Creek. the budget was able to be balanced to within 10 per cent.     

Use of magnetic and radiometric measurements to investigate erosion and sedimentation in a British upland catchment

In response to the potential shortcomings of single-technique strategies in the investigation of erosion and sedimentation, a combined magnetic and radiometric (¹³Cs and ²¹⁰Pb) approach has been undertaken in the upland, watershed-lake system of Howden Reservoir, Derbyshire. By combining these techniques, some assessment of sediment sources and the erosion status of the catchment has been achieved. Alone, each approach would have been unable to determine unequivocally sediment provenance. Furthermore, the parallel use of these measurements has highlighted limitations and/or uncertainties in both the magnetic and ¹³⁷Cs techniques. These problems reflect the particular soil characteristics and drainage conditions of this upland catchment. Despite the documented severity of peat erosion in the region, Howden Reservoir has a mixture of sediment sources and a relatively moderate rate of sedimentation. Sediment yields (total 127·7 t km^?2 yr^?1 including organic fraction 31·3 t km^?2 yr^?1) are, however, higher than in other British upland areas.     

Effects of spatially structured vegetation patterns on hillslope erosion in a semiarid Mediterranean environment: a simulation study

A general trend of decreasing soil loss rates with increasing vegetation cover fraction is widely accepted. Field observations and experimental work, however, show that the form of the cover‐erosion function can vary considerably, in particular for low cover conditions that prevail on arid and semiarid hillslopes. In this paper the structured spatial distribution of the vegetation cover and associated soil attributes is proposed as one of the possible causes of variation in cover–erosion relationships, in particular in dryland environments where patchy vegetation covers are common. A simulation approach was used to test the hypothesis that hillslope discharge and soil loss could be affected by variation in the spatial correlation structure of coupled vegetation cover and soil patterns alone. The Limburg Soil Erosion Model (LISEM) was parameterized and verified for a small catchment with discontinuous vegetation cover at Rambla Honda, SE Spain. Using the same parameter sets LISEM was subsequently used to simulate water and sediment fluxes on 1 ha hypothetical hillslopes with simulated spatial distributions of vegetation and soil parameters. Storms of constant rainfall intensity in the range of 30–70 mm h^?1 and 10–30 min duration were applied. To quantify the effect of the spatial correlation structure of the vegetation and soil patterns, predicted discharge and soil loss rates from hillslopes with spatially structured distributions of vegetation and soil parameters were compared with those from hillslopes with spatially uniform distributions. The results showed that the spatial organization of bare and vegetated surfaces alone can have a substantial impact on predicted storm discharge and erosion. In general, water and sediment yields from hillslopes with spatially structured distributions of vegetation and soil parameters were greater than from identical hillslopes with spatially uniform distributions. Within a storm the effect of spatially structured vegetation and soil patterns was observed to be highly dynamic, and to depend on rainfall intensity and slope gradient. Copyright © 2005 John Wiley & Sons, Ltd.     

Post-fire soil erosion mitigation at the scale of swales using forest logging residues at a reduced application rate

Mulching with forest residues has proved to be highly effective in reducing post-fire soil losses at the plot scale. However, its effectiveness has not been quantified at the application rates that are typically used in operational post-fire land management (2–3 Mg ha^-1 using straw), as well as at scales larger than 100 m². The present study compared post-fire erosion rates for six convergent hillslopes or swales of 500 to 800 m², three of which were left untreated while the other three were mulched immediately after the fire with shredded eucalypt bark at a rate of 2.4 Mg ha^-1. Erosion rates were monitored at irregular intervals during the first three post-fire years, whilst ground cover was assessed yearly. Selected topsoil properties (0–2 cm) such as organic matter content and aggregate stability were determined at a single occasion – two years after the wildfire, for three micro-environments separately: bare soil, and under mulch/litter and vegetation. Soil losses on the untreated swales decreased with post-fire year from 2.2 to 0.4 and 0.11 Mg ha^-1 yr^-1 (respectively for the first, second and third post-fire years), while the mulched swales produced 84%, 77% and 38% less soil losses than the untreated swales. Soil losses also depended on slope aspect, with the north-facing swales producing less erosion than the west-facing ones. This could be linked to their significant differences in bare soil, vegetation and stone cover, or a combination thereof. The type of micro-environment also played a significant role in topsoil properties (stone content, bulk density, resistance to penetration/shear stress, porosity and organic matter content). The present results add to the increasing evidence that forest residues should be duly considered for operational post-fire land management. Forest residues were highly effective in reducing erosion from swales at application rates as low as the typical 2 Mg ha^-1 of post-fire straw mulch. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.