Seeding and mulching + seeding effects on post‐fire runoff,soil erosion and species diversity in Galicia (NW Spain)

The effects of two different soil rehabilitation treatments on runoff, infiltration, erosion and species diversity were evaluated in a shrubland area in Galicia (NW Spain) after an experimental fire by means of rainfall simulations. The treatments compared were: seeding, seeding + mulching and control (untreated). Rainfall simulations were conducted 9 months after fire and the application of soil rehabilitation treatments. A rainfall rate of 67 mm h⁻¹ was applied for 30 min to each runoff plot. Seeding significantly increased plant species richness in the treated plots relative to the control plots, although it had no effect on diversity or evenness. Rehabilitation treatments did not significantly increase soil cover or affect runoff and infiltration. Soil losses were low in all cases, varying from 75·6 kg ha⁻¹ in the seeded + mulched plots to 212·1 kg ha⁻¹ in the untreated plots. However, there were no significant differences in sediment yields between treatments. The percentage of bare soil appeared to be a critical variable in controlling runoff and erosion. Copyright © 2010 John Wiley & Sons, Ltd.     

Comparing surface erosion processes in four soils from the Loess Plateau under extreme rainfall events

This research aims to improve erosion control practice in the Loess Plateau, by studying the surface erosion processes, including splash, sheet/interrill and rill erosion in four contrasting soils under high rainfall intensity (120 mm h⁻¹) with three-scale indoor artificial experiments. Four contrasting soils as sandy loam, sandy clay loam, clay loam and loamy clay were collected from different parts of the Loess Plateau. The results showed that sediment load was significantly impacted by soil properties in all three sub-processes. Splash rate (4.0–21.6 g m⁻²∙min⁻¹) was highest in sandy loam from the north part of the Loess Plateau and showed a negative power relation with the mean weight diameter of aggregates after 20 min of rainfall duration. The average sediment load by sheet/interrill erosion (6.94–42.86 g m⁻²∙min⁻¹) was highest in clay loam from middle part of the Loess Plateau, and the stable sediment load after 20 min showed a positive power relation with the silt content in soil. The average sediment load increased dramatically by rill and interrill erosion (21.03–432.16 g m⁻²∙min⁻¹), which was highest in loamy clay from south part of the Loess Plateau. The average sediment load after the occurrence of rill showed a positive power relation with clay content and a negative power relation with soil organic matter content. The impacts of slope gradient on the runoff rate and sediment load also changed with soil properties. The critical factors varied for different processes, which were the aggregate size for splash erosion, the content of silt particles and slope gradient for sheet/interrill erosion, and the content of clay particles, soil organic matter and slope gradient for rill erosion. Based on the results of the experiments, specific erosion control practices were proposed by targeting certain erosion processes in areas with different soil texture and different distribution of slope gradient. The findings from this study should support the improvement of erosion prediction and cropland management in different regions of the Loess Plateau.     

Performance of soil and water conservation practices in the erosion evolution process,runoff dynamics and surface roughness

Soil and water conservation practices are used widely to prevent soil erosion and protect soil and water resources, which is significant for ecological restoration and food security. However, rill evolution processes, erosion and deposition characteristics and critical hydrodynamic parameters need more research. In order to investigate the effect of soil and water conservation practices on soil erosion dynamics, simulated rainfall experiments were undertaken in a laboratory on 15° loess slopes with engineering measures (fish-scale pits, FSPs), tillage measures (artificial digging, AD; contour ploughing, CP) and bare slope (CK). The results showed that: (1) during rill erosion, hillslopes with FSPs, CP and AD were more likely to develop wide and shallow rills, while a bare slope (CK) was more likely to develop narrow and deep rills. At the end of the experiment (cumulative rainfall was about 150 mm), headward retreat erosion dominated the AD slope (maximum rill length: 3.27 m), side-wall expansion erosion dominated the CP slope (maximum rill width: 0.522 m) and bed incision erosion dominated the CK (maximum rill depth: 0.09 m); (2) soil and water conservation practices reduced surface erosion and sediment transport and runoff velocity. However, the positive effects disappeared when rainfall amounts exceeded 82.5, 105 and 127.5 mm for FSPs, CP and AD, respectively; (3) for runoff kinetic energy and runoff shear strength of 3 J and 1.5 N/m², respectively, soil and water conservation measures had greater anti-erosion abilities than CK; (4) as rainfall duration increased, surface roughness, runoff rate and sediment concentration increased on the CK and FSP treatments, but decreased on the CP and AD treatments. This study has important implications for managing different soil and water conservation measures based on rainfall conditions and offers a deeper understanding of soil erosion processes.     

Quantifying spatial distribution of interrill and rill erosion in a loess at different slopes using structure from motion (SfM) photogrammetry

The spatial distribution of interrill and rill erosion is essential for unravelling soil erosion principles and the application of soil and water conservation practices. To quantify interrill and rill erosion and their spatial development, four 30-min rainfalls at 90 mm h^?1 intensity were consecutively simulated on runoff plots packed with a loess at six slopes of 10°, 15°, 20°, 25°, 30° and 35°. The soil surface was measured using the structure from motion (SfM) photogrammetry upon each simulation run, and the runoff and sediment samples were collected and measured at every 10 min. Rills did not develop until the third simulation run. During the initial two runs, the lower third section was more severely eroded than the upper and middle thirds along the slope direction, yet the interrill erosion was statistically uniform from left to right. Rills tended to emerge by both sidewalls and in the lower portion in the third run. The corresponding rill erosion increased with slope from 10° to 20° and then decreased for the slopes steeper, which was consistent with the slope trend of the sediment yield directly measured. The rills expanded substantially primarily via head retreat and to a lesser extent via sideward erosion after receiving another 30-min rainfall. Rill erosion contributed 69.3% of the total erosion loss, and shifted the critical slope corresponding to the maximum loss from 20° to 25°. These findings demonstrate the significance of rill erosion not only in total soil loss but also in its relation to slope, as well as the effectiveness of SfM photogrammetry in quantifying interrill and rill erosion.     

Effects of sheet and rill erosion on soil aggregates and organic carbon losses for a Mollisol hillslope under rainfall simulation

Purpose

Characterizations of soil aggregates and soil organic carbon (SOC) losses affected by different water erosion patterns at the hillslope scale are poorly understood. Therefore, the objective of this study was to quantify how sheet and rill erosion affect soil aggregates and soil organic carbon losses for a Mollisol hillslope in Northeast China under indoor simulated rainfall.

Materials and methods

The soil used in this study was a Mollisol (USDA Taxonomy), collected from a maize field (0–20 cm depth) in Northeast China. A soil pan with dimensions 8 m long, 1.5 m wide and 0.6 m deep was subjected to rainfall intensities of 50 and 100 mm h^?1. The experimental treatments included sheet erosion dominated (SED) and rill erosion dominated (RED) treatments. Runoff with sediment samples was collected during each experimental run, and then the samples were separated into six aggregate fractions (0–0.25, 0.25–0.5, 0.5–1, 1–2, 2–5, >?5 mm) to determine the soil aggregate and SOC losses.

Results and discussion

At rainfall intensities of 50 and 100 mm h^?1, soil losses from the RED treatment were 1.4 and 3.5 times higher than those from the SED treatment, and SOC losses were 1.7 and 3.8 times greater than those from the SED treatment, respectively. However, the SOC enrichment ratio in sediment from the SED treatment was 1.15 on average and higher than that from the RED treatment. Furthermore, the loss of <?0.25 mm aggregates occupied 41.1 to 73.1% of the total sediment aggregates for the SED treatment, whereas the loss of >?0.25 mm aggregates occupied 53.2 to 67.3% of the total sediment aggregates for the RED treatment. For the organic carbon loss among the six aggregate fractions, the loss of 0–0.25 mm aggregate organic carbon dominated for both treatments. When rainfall intensity increased from 50 to 100 mm h^?1, aggregate organic carbon loss increased from 1.04 to 5.87 times for six aggregate fractions under the SED treatment, whereas the loss increased from 3.82 to 27.84 times for six aggregate fractions under the RED treatment.

Conclusions

This study highlights the effects of sheet and rill erosion on soil and carbon losses at the hillslope scale, and further study should quantify the effects of erosion patterns on SOC loss at a larger scale to accurately estimate agricultural ecosystem carbon flux.

     

缓坡面细沟发育过程及水沙关系的室内试验研究

为了明确细沟发育特征及对坡面产流产沙的作用,该文在固定坡度(10°)和2个雨强(1.5和2mm/min)条件下,采用室内纯净水模拟降雨试验的方法,研究了塿土和黄绵土的坡面细沟发育过程和水沙关系。研究结果表明,细沟主要由沿坡面方向呈线状平行分布的跌坎链相互连通演化而成,在雨强较小时塿土更易形成细沟,而黄绵土在雨强较大时才能形成细沟。含沙量与侵蚀速率的变化规律与坡面跌坎和细沟的形成具有同步关系,雨强的增大不会引起塿土含沙量和侵蚀速率的明显增加,但对黄绵土含沙量和侵蚀速率的变化有很大影响,在大雨强时黄绵土含沙量和侵蚀速率会迅速增加,并在坡面细沟形成后很快超过塿土。同时,细沟的存在并不会引起塿土含沙量和侵蚀速率的明显变化,但黄绵土对坡面细沟反应敏感,细沟一旦形成会导致其含沙量和侵蚀量的急剧增加。该研究为坡耕地细沟侵蚀的有效防治提供相应的理论指导。     

黄土区薄厚层浮土土质道路降雨侵蚀过程差异

土质道路经长期碾压产生了大量浮土,加剧了道路侵蚀.本文通过人工模拟降雨试验,研究不同雨强及坡度条件下薄层1.0 cm和厚层4.0 cm浮土土质道路的产流产沙特征.根据侵蚀物质的差异,将浮土道路侵蚀过程分为单独浮土侵蚀阶段和浮土、道路混合侵蚀阶段.结果表明:(1)浮土侵蚀阶段、混合侵蚀阶段薄层浮土平均径流率为厚层浮土的1...     

Effects of vertical hedge interval of vetiver grass on erosion on steep agricultural lands

Vetiver grass is widely used to reduce soil erosion and has been applied in many areas of the world. However, studies of the effect of vertical hedge intervals on runoff, soil loss and outflow sediment size distribution under a steep slope area are rare. The vetiver grass system (VGS) with three vertical hedge intervals (0·75, 1·5 and 3 m) and no hedgerow were tested at three land slopes (30, 40 and 50 per cent) under three simulated rainfall intensities (60, 85 and 110 mm h⁻¹). It has been observed that vetiver grass (Vetiveria nemoralis) has great potential for reducing runoff and soil loss by about 38·7–68·6 and 56·2–87·9 per cent, respectively. The vetiver strips delayed incipient runoff and reduced peak runoff rate and steady erosion rate. The land slope affected soil loss but did not have a significant effect on runoff. A narrow vetiver hedge interval slightly reduced runoff and soil loss more than a wider one. The soil loss equation obtained in this study revealed that runoff has a higher effect on soil loss. The median sediment size that passed through the vetiver strip increased with rainfall intensity and was mostly dominated by very fine sand, silt and clay. Copyright © 2009 John Wiley & Sons, Ltd.     

Simulated rainfall evaluation of revegetation/mulch erosion control in the Lake Tahoe Basin—1: method assessment

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.     

上方来水来沙对细沟侵蚀产沙过程的影响

利用双土槽系统径流小区 (供沙土槽和试验土槽 ) ,定量研究了不同上方来水含沙量和不同降雨强度下 15°坡面上方来水来沙对坡下方细沟侵蚀产沙过程的影响。结果表明 ,坡上方来沙量不但被径流全部搬运 ,且坡上方来水在坡下方细沟侵蚀槽引起另外的侵蚀产沙量 S。坡面细沟侵蚀过程以侵蚀—搬运过程为主。上方来水对细沟侵蚀产沙的贡献受上方来水含沙量和降雨强度的影响。降雨强度的增加或上方来水含沙量的减少 ,使 S值的增加更为显著     

Runoff sediment particle sizes associated with soil erosion in the Lake Tahoe Basin,USA

Runoff sediment from disturbed soils in the Lake Tahoe Basin has resulted in light scattering, accumulation of nutrients, and subsequent loss in lake clarity. Little quantified information about erosion rates and runoff particle‐size distributions (PSDs) exists for determining stream and lake loading associated with land management. Building on previous studies using rainfall simulation (RS) techniques for quantifying infiltration, runoff, and erosion rates, we determine the dependence and significance of runoff sediment PSDs and sediment yield (SY, or erodibility) on slope and compare these relationships between erosion control treatments (e.g., mulch covers, compost, or woodchip incorporation, plantings) with bare and undisturbed, or ‘native’ forest soils. We used simulated rainfall rates of 60–100 mm h⁻¹ applied over replicated 0·64 m² plots. Measured parameters included time to runoff (s), infiltration and runoff rates (mm h⁻¹), SY (g mm⁻¹ runoff), and average sediment concentration (SC, g L⁻¹) as well as PSDs in runoff samples. In terms of significant relationships, granitic soils had larger particle sizes than volcanic soils in bulk soil and runoff samples. Consequently, runoff rates, SCs, and SYs were greater from bare volcanic as compared to that from bare granitic soils at similar slopes. Generally, runoff rates increased with increasing slope on bare soils, while infiltration rates decreased. Similarly, SY increased with slope for both soil types, though SYs from volcanic soils are three to four times larger than that from granitic soils. As SY increased, smaller particle sizes are observed in runoff for all soil conditions and particle sizes decreased with increasing slope. Copyright © 2008 John Wiley & Sons, Ltd.     

Rill formation and evolution caused by upslope inflow and sediment deposition on freshly tilled loose surfaces

Rill erosion easily occurs on tilled surfaces because the soil shear resistance is less than the runoff shear stress. However, rill erosion formation and evolution on tilled surfaces under upslope inflow conditions remain unclear. The objective of this study was to investigate the rill formation process and rill erosion amount on tilled surfaces via flow scouring under different inflow rates (4, 6, and 8 L min⁻¹) at a 15° slope. Close-range photogrammetric technology was applied to measure the rill morphology during the experiments. The results suggested that the rill formation process due to inflow could be divided into two distinct stages, namely, before and after runoff reached the downslope end, i.e., stages I and II, respectively. At stage I, runoff washed soil particles along the downslope direction. In this process, due to limited transport capacity of runoff, washed soil particles were deposited at the runoff head and formed a soil mound, which blocked the flow path, after which the runoff direction changed within the 6.7°− 50.6° range with an average moving distance of 0.62 m. As a result, a curved rill and a series of soil mounds were left on the surface. The inflow rate affected rill morphology by influencing the runoff direction change angle and runoff moving distance between the mounds on the surface. Herein, the rill formation process is referred to as downslope-trending erosion by inflow (DTEI). At stage II, runoff reached the downslope end, and a rill channel was formed throughout the slope. Thereafter, DTEI was largely reduced, and headward erosion was strengthened. As a result, the rill morphology quickly changed, such as the rill depth and rill width, which gradually increased with ongoing headward erosion. During DTEI, the rill paths were curved due to sediment deposition, and the sediment deposition conditions varied under the different inflow rates. Therefore, the rill curvature (RC) differed (1.039 ± 0.014). The RC decreased with headward erosion progression at stage II. The total sediment yield (TSY) increased with increasing inflow rate. Under inflow rates ranging from 4 to 6 L min⁻¹ and 6–8 L min⁻¹, the TSY increased 2.1–2.4 times. Consequently, DTEI on tilled surfaces significantly affects the initial rill morphology and evolution at the later stage. Hence, on slopes, its role should be considered in rill erosion assessment.     

模拟降雨下坡面微地形量化及其与产流产沙的关系

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。     

Effects of Underground Pore Fissures on Soil Erosion and Sediment Yield on Karst Slopes

Underground pore fissure is one of common ways of soil leakage, and the soil loss in underground pore fissure would aggravate the development of rocky desertification in karst areas. A designed steel tank with varied underground pore fissure degrees was used to measure how underground pore fissure affected soil erosion and sediment yield on karst bare slope. We found that sediment yield rates and its distribution ratios obviously differed between the surface and underground. Surface sediment yield rate greatly responded to rainfall intensity conditions, while underground sediment yield rate rarely changed. Both bed rock bareness and underground pore fissure degree had an insignificant effect on both surface and underground sediment yield rate, but the former greatly influenced sediment distribution between the surface and underground. With increasing of bed rock bareness rate, both the average surface and underground sediment yield rates first increased and then decreased. The later posed an effect on underground sediment yield rate, which increased with increase of underground pore fissure degree. With increase of underground pore fissure degree, critical rainfall intensity for producing surface sediment would increase from 0.8–1.3 mm min⁻¹ to 1.3–2.0 mm min⁻¹. The results provide a mechanistic understanding of how underground pore fissure affects soil erosion and sediment production. Copyright © 2017 John Wiley & Sons, Ltd.     

Effects of simulated wind followed by rain on runoff and sediment yield from a sandy loessial soil with rills

Purpose

Severe soil erosion is caused by wind and water acting separately or in combination or sequentially and is an important factor affecting dryland ecosystems, especially in the severely eroded “water–wind erosion crisscross region” on the Loess Plateau. Thus, the aim of the study was to determine the magnitudes of wind and water erosion under simulative conditions and explore the mechanisms of their interactions.

Materials and methods

We analyzed the interaction between these two types of erosion by exposing a sandy loessial soil with an artificial rill to simulated wind at four speeds (0, 1, 8, and 15 m s^?1) and then to simulated rainfall, measuring runoff, sediment yield, and characterizing changes in rill morphology. This simulated the transition period between the dry (windy) and wet seasons.

Results and discussion

The time to runoff initiation depended on both wind speed and rainfall intensity, but rainfall had a larger impact on runoff. At the 15 m s^?1 wind speed, the total runoff significantly (P?<?0.05) increased by 33.3 kg when the rainfall intensity was increased to 120 from 60 mm h^?1. Under the 120 mm h^?1 rainfall intensity, the total sediment yields increased significantly (P?<?0.05) with increasing wind speed. Erosion sediment yields increased by 9.7, 16.3, and 70.4 % with increasing wind speed under all three rainfall intensities when compared with a no wind case. Changes in rill morphology caused by wind erosion were a factor that affected the erosion processes of subsequent rainstorms.

Conclusions

Our results provide a basis for hypothesizing trends of wind and water erosion, highlight the importance of wind and water erosion acting in conjunction in semi-arid ecosystems, and are conducive for developing a more integrated perspective of wind–water dynamics on the Loess Plateau.

     

坡长对侵蚀产沙过程影响的模拟研究

通过室内模拟降雨试验探讨了坡长对侵蚀产沙过程的影响规律。实验结果表明 ,坡长是影响径流、侵蚀产沙的重要因素 ,径流量与坡长呈线性关系 ,侵蚀量与坡长基本呈指数关系。累积径流量与累积侵蚀产沙量均与降雨历时呈明显的直线关系 ,其斜率随坡长的增加而增大。坡长对侵蚀形态的演化也有重要作用 ,在试验条件下 ,0 .72 mm/ min雨强下 2 .5 ,5 ,7.5 ,10 m坡长小区均未发生细沟侵蚀 ;雨强增至 1.14mm / min时 ,10 m小区发生了细沟侵蚀 ;雨强大于 1.14mm / min时 ,7.5 m以上的小区均有细沟侵蚀发生。细沟发育时 ,坡面径流、侵蚀产沙量猛增 ,水流含沙量也出现了跳跃性增加     

黄土坡面细沟形态变化及对侵蚀产沙过程的影响

为揭示细沟形态对侵蚀产沙过程的影响,选取66、94、127 mm/h三个雨强条件,对20°陡坡坡面进行了坡面水蚀精细模拟降雨试验,选取沟长、沟宽、沟深等指标刻画细沟形态随降雨历时的变化规律。结果表明:1)降雨强度对细沟长度的影响显著,细沟宽度变化受降雨历时的影响较大,细沟深度的变化对降雨强度表现出较强的分异规律。2)细沟形态参数之间不是相互独立的,存在明显的相关关系,说明细沟形态的演变是一个多维度过程。3)细沟的形成和发展与坡面水沙过程关系密切,细沟形态参数与含沙量、侵蚀速率之间均存在较显著的对数函数关系。该研究可以为细沟侵蚀动态模型的建立提供基础数据。     

细沟侵蚀过程与细沟水流水力学参数的关系研究

利用供沙土槽和试验土槽的双土槽径流小区 ,定量研究了在不同降雨强度下上方来水来沙对陡坡地细沟侵蚀产沙过程和细沟水流水力学参数的影响及其细沟水流水力学特征参数与细沟侵蚀产沙量的关系。结果表明 :坡面细沟侵蚀过程以侵蚀—搬运过程为主 ,坡上方来沙不仅被径流全部搬运 ,且上方来水在坡下方引起了另外的侵蚀产沙量 ,其值随上方来水含沙量的减少和降雨强度的增加而增大。上方来水的汇入或降雨强度的增大可使细沟水流流态由层流转化为紊流。上方来水对细沟水流水力学参数 (流速、水力半径、雷诺数、弗劳德数和阻力系数 )有重要影响。定量分析了细沟水流水力学特征参数 (流速、雷诺数和阻力系数 )与上坡来水引起坡下方净侵蚀产沙量的关系 ,建立了净侵蚀产沙量与细沟水流流速、雷诺数和阻力系数统计模型。     

Dynamics of Runoff and Suspended Sediment Transport in a Highly Erodible Catchment on the Chinese Loess Plateau

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.