Deep Erosion Research Articles

Geo-risk analysis of slopes bounding a deep gully erosion site in Uyo, Akwa-Ibom State, Southeastern Nigeria

The stability of slopes around a deep gully erosion site is the subject of this article. The site geology is the Coastal Plain Sands. To carry out stability analysis, the slopes were first characterized by deployment of cone and standard penetration tests (CPT and SPT) equipment. The slopes are highly stratified, and consist of numerous layers up to the depth of investigation which is about 37.0 m. The slope is made up of five layers of materials up to the gully valley floor. The soils of the five layers in succession from the top are clayey sand (SC), clayey/silty sand (SC–SM), gravelly clay (GC), poorly graded gravel with well graded sand mixture (GP–SW), and well graded sand (SW). Two locations on the eastern side of the of the gully site which poses serious risk to lives and properties were chosen for the analysis. The first position with the highest slope of 16.0 m gave a critical factor of safety less than 1.5 based on simplified Bishop method of analysis indicating unstable slope, while the second location results in a factor of safety greater than 1.5 suggesting a more stable slope, although there is a potential of sheet erosion on the slope at this location.

Hydrological effects of the hydraulic structures constructed in the valley of the River Little Vistula in Poland from the mid-18th century to the present

Abstract This study of the hydraulic structures constructed in the River Little Vistula (Mała Wisła) valley covers its western reach from the village of Strumień (Schwartzwasser) to the mouth of the River Przemsza. Its purpose was to assess the impact of these structures on changes in the conditions of runoff formation within the valley from the mid-18th century to the present. Historical materials (maps, sketches and plans) collected in the State Archives in Opole and Katowice were used in the study. Analyses of Austrian plane-table maps from the years 1763–1764 and 1861–1862 (1:28 800 scale) and of Prussian maps from the years 1827–1828 and 1881–1883 (1:25 000 scale) were also conducted. As a result of the study, the type and rate of hydraulic works were determined along with the techniques and methods used when constructing these structures in the 18th and 19th centuries. It was found that during the last 260 years, the main channel of the River Little Vistula moved within the meandering zone. Within the area of the Zarzecze and Mała Wisła settlements, a “new” River Vistula channel was formed during the flood in 1736, which shifted ca. 0.5–1.0 km to the south. The hydraulic structures which were constructed, mainly levees, caused water levels to rise excessively in the area during high water stages and the swollen waters often causing the levees to cave in, or to breach them. The river engineering work which was conducted also affected the formation of runoff in the valley of the River Little Vistula. It has been found that both anastomosis processes and river meandering were inhibited. In some channel reaches, temporal activation of deep erosion processes as well as channel shallowing were observed. Deep erosion reached up to 2 metres and channel shallowing up to 1 metre. These processes took place during river engineering work and the River Vistula bed took around a dozen years to stabilise following the completion of the work.

Origin of Little Missouri River - South Fork Grand River and nearby Drainage Divides in Harding County, South Dakota and Adjacent Eastern Montana, USA

Barbed tributaries flowing in southeast directions, an asymmetric drainage divide with both the South Fork Grand River and the North Fork Moreau River, and the Jump-off escarpment-surrounded basin (interpreted here to be a large abandoned headcut) are examples of topographic map evidence suggesting the north oriented Little Missouri River valley eroded headward across a large southeast oriented anastomosing complex of ice-marginal melt water flood flow channels that once crossed Harding County, South Dakota. Additional evidence includes southeast oriented tributaries to the northeast oriented South Fork Grand River and multiple divide crossings (e.g. through valleys and wind gaps) on the Boxelder Creek-Little Missouri River divide (in eastern Montana and west of the Little Missouri River) and suggests deep regional erosion occurred as the north oriented Little Missouri River valley eroded headward into and across the region. Harding County is located south and west of the southwest limit of coarse-grained glacial erratic material and ice-marginal melt water flow routes logically should have crossed it. Deep melt water erosion of Harding County and adjacent eastern Montana regions to the west is not consistent with many previous drainage history and glacial history interpretations, but is consistent with deep erosion by continental ice sheets.

Numerical study of thermal erosion and topographical change of divertor target plates induced by type-I edge-localized modes

The high-Z material tungsten (W) is a promising candidate of the plasma facing components (PFCs) for the future tokamak reactors due to its high melting point (3683 K), low tritium retention and low sputtering yield. However, there are still many problems about W PFCs. One of them is the material melting under off-normal transient heat fluxesit is one of the most outstanding open questions associated with the use of W divertor targets in international thermonuclear experimental reactor (ITER). This requires us urgently to understand the W melting behavior under high power flux deposition condition. In this paper, a two-dimensional (2D) fluid dynamic model is employed by solving the liquid hydrodynamic Navier-Stokes equation together with the 2D heat conduction equation for studying the erosion of the divertor tungsten targets and its resulting topographical modification during a type I-like edge-localized mode (ELM) in ITER with a Gaussian power density profile heat load. In the present model, major interaction forces, including surface tension, pressure gradient and magnetic force responsible for melt layer motion, are taken into account. The simulation results are first benchmarked with the calculated results by other code to validate the present model and code. Simulations are carried out in a wide range of fusion plasma performance parameters, and the results indicate that the lifetime of W plate is determined mainly by the evolution of the melt layer. As a consequence of the melt layer motion, melted tungsten is flushed to the periphery, a rather deep erosion dent appears, and at the dent edges two humps of tungsten form during the ELM. The humps at both edges are almost at the same height. Calculated results show the topographical modification becomes noticeable when the W plate is exposed to a heat flux of 2000 MWm-2 for 0.8 ms (in the simulation, the parameter k=ə/əT is taken to be -9.010-5 Nm-1K-1, where is the surface tension coefficient and T is the temperature). The values of the humps are both about 2.1 m, and the surface roughness is about 1.1 m. The longer the duration of the ELM, the more rapidly the humps rise. The melt flow may account for the higher surface temperature at the pool periphery, and for the larger melt thickness. It is found that when the energy flux is under 3000 MWm-2 the surface tension is a major driving force for the motion of melt layer. Under the same heat flux, the bigger the k used in the simulation, the more severe the surface topography of the target becomes; while at the same k, the higher the heat flux, the more severe the surface topography of the target becomes. In addition, a modified numerical method algorithm for solving the governing equations is proposed.

The Press Committee of the Central Committee of the Polish United Workers’ Party, 1956–1957

In 1955–1956 the communist system underwent deep erosion, and one of the most important and evident signs of it was decreased control the party exercised over propaganda. This gave the press wide readership, and made some of journalists feel as representatives of the people. Wladyslaw Gomulka’s coming to power began a process of consolidation of the system and regaining of stability – this applied to the whole system, including propaganda. The Press Committee of the Central Committee of the Polish United Workers’ Party was meant as a concession to journalists: they were given a forum to formulate in which they could legally formulate their postulates for the price of loyalty to Gomulka. From the very beginning, however, the journalists who were members of the Press Committee and the party leaders had diverging interests. This made the actual activity of the Committee very limited. The political subjectivity of journalists was brutally challenged in the autumn of 1957, which was marked by a symbolic closure of the weekly Po Prostu . The Press Committee underwent a fundamental restructuring and its tasks changed. But a period of several months of its existence makes an important contribution to the political history of the press and propaganda in the Polish People’s Republic.

Influence of topography and human activity on apparent in situ <sup>10</sup>Be-derived erosion rates in Yunnan, SW China

Abstract. In order to understand better if and where erosion rates calculated using in situ 10Be are affected by contemporary changes in land use and attendant deep regolith erosion, we calculated erosion rates using measurements of in situ 10Be in quartz from 52 samples of river sediment collected from three tributaries of the Mekong River (median basin area = 46.5 km2). Erosion rates range from 12 to 209 mm kyr−1 with an area-weighted mean of 117 ± 49 mm kyr−1 (1 standard deviation) and median of 74 mm kyr−1. We observed a decrease in the relative influence of human activity from our steepest and least altered watershed in the north to the most heavily altered landscapes in the south. In the areas of the landscape least disturbed by humans, erosion rates correlate best with measures of topographic steepness. In the most heavily altered landscapes, measures of modern land use correlate with 10Be-estimated erosion rates but topographic steepness parameters cease to correlate with erosion rates. We conclude that, in some small watersheds with high rates and intensity of agricultural land use that we sampled, tillage and resultant erosion has excavated deeply enough into the regolith to deliver subsurface sediment to streams and thus raise apparent in situ 10Be-derived erosion rates by as much as 2.5 times over background rates had the watersheds not been disturbed.

Eustatic and tectonic change effects in the reversion of the transcontinental Amazon River drainage system

ABSTRACT: The development of the transcontinental Amazon River System involved geological events in the Andes Chain; Vaupés, Purus and Gurupá arches; sedimentary basins of the region and sea level changes. The origin and age of this river have been discussed for decades, and many ideas have been proposed, including those pertaining to it having originated in the Holocene, Pleistocene, Pliocene, Late Miocene, or even earlier times. Under this context, the geology of the sedimentary basins of northern Brazil has been analyzed from the Mesozoic time on, and some clarifications are placed on its stratigraphy. Vaupés Arch, in Colombia, was uplifted together with the Andean Mountains in the Middle Miocene time. In the Cenozoic Era, the Purus Arch has not blocked this drainage system westward to marine basins of Western South America or eastward to the Atlantic Ocean. Also the Gurupá Arch remained high up to the end of Middle Miocene, directing this drainage system westward. With the late subsidence and breaching of the Gurupá Arch and a major fall in sea level, at the beginning of the Late Miocene, the Amazon River quickly opened its pathway to the west, from the Marajó Basin, through deep headward erosion, capturing a vast drainage network from cratonic and Andean areas, which had previously been diverted towards the Caribbean Sea. During this time, the large siliciclastic influx to the Amazon Mouth (Foz do Amazonas) Basin and its fan increased, due to erosion of large tracts of South America, linking the Amazon drainage network to that of the Marajó Basin. This extensive exposure originated the Late Miocene (Tortonian) unconformity, which marks the onset of the transcontinental Amazon River flowing into the Atlantic Ocean.

THE FEATURES OF THE OKA RIVER LONGITUDINAL PROFILE DEVELOPMENT UNDER THE ANTHROPOGENIC DISTURBANCES OF THE RIVER BED

Based on the analysis of cartographic documents and hydrological data, as well as detailed studies of fl uvial processes in the Upper Oka, carried out in 1990-ies and continued in 2010–2015, it was found that the longitudinal profile of the river was significantly infl uenced by anthropogenic river bed disturbances – exploitation of in-stream mines of alluvial construction materials, concentrated in the middle reaches of the river within 400–800 km from the source. Changes in river bed morphology and sediment deficiency has resulted in the deep erosion. To determine the role of anthropogenic disturbance in the longitudinal profile formation, in accordance with the N.I. Makkaveyev’s approach, the calculation of graded longitudinal profile and its comparison with real one were performed. By calculating the stream-gradient index proposed by J. Hack, the uneven gradient distribution was revealed along the entire river and on separate typical sections. The highest values of the stream-gradient index observed at the site where mechanical modifications are the most – between Kaluga and Kolomna Cities. On this stretch of the river in the late 1930s, the longitudinal profile in most aspects practically coincides with the calculated graded profile. However, mechanical changes of the river bed and the accompanying river bed degradation has led to the fact that along with general elevation decrease, profile became ungraded, and one can expect some deformations aimed at its restoration. As a result, the difficulties in using the resources of the river, which emerged in the early 1990-ies, have increased.

Late Pliocene–Pleistocene stratigraphy and history of formation of the Ioffe calcareous contourite drift, Western South Atlantic

The high-resolution SES-2000 deep seismic profiles performed by R/V Akademik Ioffe (2010) recorded a calcareous contourite drift over the Florianopolis fracture zone ridge, South Atlantic, named the Ioffe Drift. Core AI-2436 retrieved from the drift summit recovered calcareous nannofossil–foraminiferal ooze contourites with small amounts of fine-grained terrigenous siliciclastic material. The calcareous ooze is intercalated with foraminiferal sand and more clayey ooze layers in the Upper Pleistocene section. According to planktonic foraminiferal and nannofossil biostratigraphy, the age of the uppermost section of the drift ranges from the Late Pliocene to the Late Pleistocene. It includes several stratigraphic hiatuses due to erosion, especially at the end of Pliocene–Early Pleistocene and in the intervals 1.51–0.81 and 0.44–0.27Ma. The Ioffe Drift accumulated under the influence of the eastern branch of the Antarctic Bottom Water (AABW) outflow from the Vema Channel. Temporary intensification of the AABW flow, likely due to its increased production in the Weddell Sea, led to deep erosion ultimately resulting in long-term hiatuses and hence contributing to the enormously compressed Upper Pliocene–Middle Pleistocene section of the drift.

Attenuation of wall-thinning rate in deep erosion by liquid droplet impingement

This paper describes an experimental study on the wall-thinning rate in deep erosion by liquid droplet impingement (LDI) in a pipeline for application to nuclear/fossil power plant. The experiment is carried out in a spray jet apparatus, which allows the evaluation of local wall-thinning rate by the LDI erosion. The surface contour of erosion and the wall-thinning rate are measured and the observation by scanning electron microscope (SEM) is carried out in this experiment. The experimental result indicates that the wall-thinning rate is highly attenuated and the macro structure on the erosion surface grows with an increase in the erosion depth, which is due to the influence of the liquid film over the erosion surface. The erosion model for predicting the wall-thinning rate in deep erosion is proposed by introducing the attenuation factor with a function of erosion depth. The introduction of attenuation factor with liquid-film effect shows a better correlation with the experimental data, and the accuracy of correlation is improved by a factor of 2.

Water droplet erosion mechanism of nearly fully-lamellar gamma TiAl alloy

Water droplet erosion (WDE), is a known mechanical degradation and progressive damage for turbine blades in the power generation and aerospace industries. Hence, water droplet erosion study of TiAl as an important structural material in such industries would be very attractive. The current work is to investigate the erosion damage mechanism of nearly fully lamellar Ti45Al2Nb2Mn0.8TiB2 (45-2-2XD) alloy. This alloy was subjected to water droplet erosion using 460μm droplets and 350ms−1 impact speed. In order to track the erosion damage, WDE test was interrupted at different stages; incubation, maximum erosion rate and final steady state stages. The eroded specimens were characterized using optical microscope (OM), scanning electron microscope (SEM) and atomic force microscope (AFM). The qualitative and quantitative study reveals that the erosion damage of TiAl initiates by inhomogeneous and localized material flow followed by crack network generation on the surface. Such cracks mainly nucleate on the interlamellar slip bands and cause delamination of lamellae. Further droplet impacts result in the cracks coalescence and subsequent micro-pitting within the colonies. In the advanced stages, the erosion damage was governed by periodic water roughening and water polishing, which were observed on the bottom and the sidewalls of deep erosion craters.

Exceptional hydrological phenomena in the Gemenea catchment

Flash floods, accompanied by high waters and regular floods, represent the most dangerous natural hazards in the Gemenea catchment, inducing other risks such as geomorphologic, environmental, social and economical risks. Flash floods occurred during the 1969 to 2014 monitoring interval are characterized by extremely high discharge values, of 68.9 m3/s in 2006 and 95.3 m3/s in 2008 and a magnitude 2.5 times higher than the average discharge recorded until that timeframe. With an area of 77.7 km2, the Gemenea catchment falls into the category of small catchments, where the peak discharge during exceptional hydrological phenomena is caused by torrential rainfall. Flash floods of particularly high intensities caused serious damages through: total destruction or damage of the torrent correction works, clogging of culverts on catchment forest roads, failure of river banks and deterioration of the bridges that affected roads and homes in Gemenea, Slatioara and Stulpicani villages. These floods have also caused damage to the forest/agriculture fund through deep and lateral erosion, failure of river banks and landslides. Within this study we aim to emphasize the magnitude, frequency, duration and area of manifestation of such phenomena in the Gemenea catchment. Furthermore, we aim to advance our knowledge of the genesis and specific mechanisms of flash flood occurrence for reducing their negative impacts on the local environment and communities

An ignimbrite caldera from the bottom up: Exhumed floor and fill of the resurgent Bonanza caldera, Southern Rocky Mountain volcanic field, Colorado

Among large ignimbrites, the Bonanza Tuff and its source caldera in the Southern Rocky Mountain volcanic field display diverse depositional and structural features that provide special insights concerning eruptive processes and caldera development. In contrast to the nested loci for successive ignimbrite eruptions at many large multicyclic calderas elsewhere, Bonanza caldera is an areally isolated structure that formed in response to a single ignimbrite eruption. The adjacent Marshall caldera, the nonresurgent lava-filled source for the 33.9-Ma Thorn Ranch Tuff, is the immediate precursor for Bonanza, but projected structural boundaries of two calderas are largely or entirely separate even though the western topographic rim of Bonanza impinges on the older caldera. Bonanza, source of a compositionally complex regional ignimbrite sheet erupted at 33.12 ± 0.03 Ma, is a much larger caldera system than previously recognized. It is a subequant structure ∼20 km in diameter that subsided at least 3.5 km during explosive eruption of ∼1000 km 3 of magma, then resurgently domed its floor a similar distance vertically. Among its features: (1) varied exposure levels of an intact caldera due to rugged present- day topography—from Paleozoic and Precambrian basement rocks that are intruded by resurgent plutons, upward through precaldera volcanic floor, to a single thickly ponded intracaldera ignimbrite (Bonanza Tuff), interleaved landslide breccia, and overlying postcollapse lavas; (2) large compositional gradients in the Bonanza ignimbrite (silicic andesite to rhyolite ignimbrite; 60%–76% SiO 2 ); (3) multiple alternations of mafic and silicic zones within a single ignimbrite, rather than simple upward gradation to more mafic compositions; (4) compositional contrasts between outflow sectors of the ignimbrite (mainly crystal-poor rhyolite to east, crystal-rich dacite to west); (5) similarly large compositional diversity among postcollapse caldera-fill lavas and resurgent intrusions; (6) brief time span for the entire caldera cycle (33.12 to ca. 33.03 Ma); (7) an exceptionally steep-sided resurgent dome, with dips of 40°–50° on west and 70°–80° on northeast flanks. Some near-original caldera morphology has been erosionally exhumed and remains defined by present-day landforms (western topographic rim, resurgent core, and ring-fault valley), while tilting and deep erosion provide three-dimensional exposures of intracaldera fill, floor, and resurgent structures. The absence of Plinian-fall deposits beneath proximal ignimbrites at Bonanza and other calderas in the region is interpreted as evidence for early initiation of pyroclastic flows, rather than lack of a high eruption column. Although the absence of a Plinian deposit beneath some ignimbrites elsewhere has been interpreted to indicate that abrupt rapid foundering of the magma-body roof initiated the eruption, initial caldera collapse began at Bonanza only after several hundred kilometers of rhyolitic tuff had erupted, as indicated by the minor volume of this composition in the basal intracaldera ignimbrite. Caldera-filling ignimbrite has been largely stripped from the southern and eastern flank of the Bonanza dome, exposing large areas of caldera-floor as a structurally coherent domed plate, bounded by ring faults with locations that are geometrically closely constrained even though largely concealed beneath valley alluvium. The structurally coherent floor at Bonanza contrasts with fault-disrupted floors at some well-exposed multicyclic calderas where successive ignimbrite eruptions caused recurrent subsidence. Floor rocks at Bonanza are intensely brecciated within ∼100 m inboard of ring faults, probably due to compression and crushing of the subsiding floor in proximity to steep inward-dipping faults. Upper levels of the floor are locally penetrated by dike-like crack fills of intracaldera ignimbrite, interpreted as dilatant fracture fills rather than ignimbrite vents. The resurgence geometry at Bonanza has implications for intracaldera-ignimbrite volume; this parameter may have been overestimated at some young calderas elsewhere, with bearing on outflow-intracaldera ratios and times of initial caldera collapse. Such features at Bonanza provide insights for interpreting calderas universally, with respect to processes of caldera collapse and resurgence, inception of subsidence in relation to progression of the ignimbrite eruption, complications with characterizing structural versus topographic margins of calderas, contrasts between intra- versus extracaldera ignimbrite, and limitations in assessing volumes of large caldera-forming eruptions. Bonanza provides a rare site where intact caldera margins and floor are exhumed and exposed, providing valuable perspectives for understanding younger similar calderas in some of the world9s most active and dangerous silicic provinces.

Risks Associated To Present Geomorphologic Processes In The Stemnic (Buda) River Basin

Abstract The paper analyses the main geomorphologic processes in the Stemnic (Buda) river basin, conditioned by the joint action of several factors, among which are the lithological peculiarities and the nature of superficial deposits, morphometric characteristics, climate, vegetation type and structure, properties of the soil cover etc. The Stemnic river basin with an area of 15662.52 ha is characterized by its elongated shape (the maximum length is of 30.5 km, maximum width of 8.5 km), its relative lithological homogeneity, but also by a variety of superficial deposits (eluvium, diluvium, colluvium and proluvium, alluvium) and by a relief energy of significant values between 136 m and 10 m (mean value of 73 m). Under these conditions, study area is characterized by a high degree of susceptibility to the occurrence of geomorphologic risk processes. For the morphometric and morphological analysis, we applied the method of the digital terrain model (DTM) with vectorisation of the contour lines on topographic maps with a scale of 1:5,000. In this paper we used indicators that highlight the particular frequency of landslides, especially in the upper and middle sectors, but the rather reduced frequency of deep erosion. Due to the satisfactory coverage of the ground with vegetation, the erosion reaction is differentiated, as it depends on the use of the land and the concentration of liquid flow on the slopes. Consequently, landslides of different ages, types and forms hold large surfaces in the basin (approx. 8%), while surface erosion affects most areas of the slopes, but with different intensities depending on their use and on agricultural technologies.

GEOGRAPHICAL ANALYSIS OF THE VERTICAL RIVER CHANNELS DEFORMATION IN THE EAST EUROPE AND ASIA

Spatial regularities of long-term deep erosion and accumulation on the rivers of the East Europe and Asia are analyzed. In the intracontinental regions incision is predominant, its value depending on the velocity of the tectonic uplift. Accumulation appears on the rivers, which cross marginal and littoral lowlands, with its velocity increasing southwards up to enormous values according to the solid runoff growth and the velocity of river mouth prograding. Muddying is characteristic of little rivers of the steppe and south forest zones due to excess of soil erosion material.

RECENT GEOMORPHOLOGIC REGIMES OF THE URAL

The territory of the Ural neotectonic structural zone consists of several areas with highly different recent geomor-phologic regimes. For the mountainous regimes of the North and Polar Ural the typical are high values of neotectonic 4* 83 uplift, deep and dense erosion dissection, high gradients of elevations, glacial landforms. The regimes of plain type are characterized by insignificant dissection under condition of low uplift; they occupy Pai-Khoi, the eastern margin of the Ural and Transural plateau. The intermediate regimes have intermediate values of neotectonic uplift, elevations, and erosion dissection, but high intensity of karst and landslides, and large amount of woodland; they are situated on the west slope of the North and Middle Ural and in the NW part of the South Ural. The Ural is usually classified as a single mountain morphostructural type with subtypes. We suppose there should be three or at least two mor-phostructural types: the properly mountain, the transitional, and platform plain types of morphostructure within the Ural neotectonic region (the last two may possibly be merged into one transitional type). These types manifest the different stages or different intensity of the Ural's rejuvenation (or regeneration). The distribution of recent geomor-phologic regimes is governed not only by the Hercynian meridional tectonic structures but by the latitude climatic zones and neotectonic features as well.

LANDFORMS AND AGE OF THE LENA RIVER ALLUVIAL COVER AT THE "YAKUT ROBBERY"

The alluvium of the Lena River below the Pokrovsk town was particularly analyzed including pollen analysis. There exists the single terrace above flood-plain build up with Drias-Holocene deposits and high and low infill flood-plains; they were formed over the three main stages. During global cooling in the period 20-17 ma b. p. the base level of the Lena was low and deep erosion prevailed. During warm period 164.5 ma (Drias) the base level upraised and alluvium was accumulated in the valley. At the third stage up to nowadays the transit of earlier accumulated material is predominant. In the result, the channel section changes frequently as well as its carrying capacity, which leads to gorges formation and flooding of large areas.

Comparison of volumetric and remote sensing methods (TLS) for assessing the development of a permanent forested loess gully

The gully systems develop a compact network dissecting the loess cover of the NW part of the Lublin Upland. They are overgrown by dense and multi-storey forest assemblages. It is very difficult to apply teledetection techniques, GPS positioning, and geodesic tools, such as a laser rangefinder or total station, for monitoring of gully development. The detailed research, involving the comparison of traditional and modern methods, was conducted in a gully with a secondary erosional dissection, developing in the gully bottom with varied intensity for the last 15 years. In the period of comparative research (2012/2013), the rate of development of the erosional dissection was measured by means of traditional methods as well as a Leica HDS 7000 laser scanner. 3D laser scanning permitted precise terrain modelling and the assessment of qualitative and quantitative spatial changes. This paper compares the results of three measurement campaigns. The analysis showed intensive development of the dissection, manifested in an increase in its volume (37 %), retreat of the erosion scarp (32 m), deep erosion (19 %), and lateral erosion (27 %). Registered moderate snowmelt in 2013 caused the volume dissection to increase by 57 m3, mainly as a result of the gully bottom scouring. During heavy rainfalls in June, the landforms were widened by a further 217 m3 and observed deepening and widening of erosive potholes. The prevalence of deep erosion resulted in the transformation back into a V-shaped cross section. A total of 37.3 Mg km−2 of material was discharged from the gully catchment during snowmelt runoffs in 2013. A precipitation event in June 2013 caused the discharge of 856.9 Mg km−2 of material from the catchment. The obtained results confirm that snowmelt erosion determines the spatial development of perennial gullies, but the volume of material discharged from the catchment depends on the occurrence of extreme precipitation during the warm season.

Negative impacts of afforestation and economic forestry on the Chinese Loess Plateau and proposed solutions

Severe loss of soil and water on the Chinese Loess Plateau (CLP) has caused enormous pressure on social and economic development. To restore the ecological environment and boost the economy, the government has invested heavily in afforestation programmes and encouraged local farmers to plant trees that are economically productive. Although these measures have led to considerable increases in the economic value of forests and some farmers' income, negative effects on the environment, such as deep soil desiccation, soil erosion, and environmental pollution, have increased over time. Our field observations show that non-native forests are not well suited to controlling soil erosion unless a protective ground herb cover is also present. To identify the natural vegetation type on the CLP, pollen records from various topographic units were collected and synthesized. The results show that herbs, mainly from the Poaceae and Asteraceae families, were dominant during both the cold-dry period and warm-humid period. The reason for the dominance of these species is that the moisture in the surface soil is insufficient to sustain forests in the CLP where rainwater infiltrates quickly into the thick, loose loess. The ecological restoration of herbs from the Poaceae and Asteraceae families on the CLP should be considered a priority, and trees can grow well only in areas covered by thin loess deposits with efficient underlying water-resisting layers and a high underground water table. Because Asteraceae are such an important source of medicines, the CLP has great potential to be an important centre for Chinese medicinal herb production. We therefore recommend an expansion of the cultivation of medicinal herbs at the expense of high-value economic trees and pasture grasses, both of which consume large quantities of water.

Multinational Corporations and the Transforming Operational Environment in China

China and the multinational corporations (MNCs) have had a long period of close relationship. In locating operations in China, MNCs beneficially followed the principle of least‐cost location. However, China's economic and business environment has been undergoing a striking transformation. The Chinese economy is losing some of its beneficial emerging‐market traits. Many foreign business enterprises and MNCs have experienced deep erosion of profits. This article first focuses on the growing importance of China and the Chinese markets for foreign business firms and MNCs. The sheer size of the market naturally draws them in. Next, it dwells on the challenges that have evolved over the years and the budding new business environment, often referred to as “the new normal.” Many MNCs realize the need to adapt to the new operating environment in China. This article proposes a list of adaptive and coping measures for the foreign enterprises and MNCs. © 2015 Wiley Periodicals, Inc.