Des E Walling

• BA, PhD
• Professor Emeritus at University of Exeter

The migration of rivers in permafrost landscapes has critical implications for riverine infrastructure, ecosystem stability, and carbon cycling, yet its magnitude and underlying mechanisms remain poorly understood. Here, we leverage four decadal satellite imagery, hydrological observations, and permafrost modeling to investigate meander migration d...

Fluvial sediment transport, a key pathway for global biogeochemical cycling, has changed markedly in the Anthropocene. However, disaggregating the compound effects of anthropogenic stresses on fluvial sediment transport at the global scale remains a challenge. Here we map the suspended sediment concentrations for global river channels, based on sat...

Investigating erosion and river sediment yield in high-mountain areas is crucial for understanding landscape and biogeochemical responses to environmental change. We compile data on contemporary fluvial suspended sediment yield (SSY) and 12 environmental proxies from 151 rivers in High Mountain Asia surrounding the Tibetan Plateau. We demonstrate t...

Erosion and sediment-related problems are well documented globally and continue to warrant further scientific investigation, as well as improved policies and management strategies to protect soil and water resources. The International Commission on Continental Erosion (ICCE) has long been a very active commission of the International Association of...

In this chapter, all studies on 137Cs resampling collected from the literature as well as the recent contributions carried out by the authors of this guidelines are presented. The grouping of assembled studies was based on their geographical provenience. All discussed contributions were arranged into four subchapters: 2.1 North America and Australi...

Sediment source fingerprinting has been progressively developed and refined over the past 40 years or more and now represents a widely used and valuable technique, with important practical applications. However, relatively little attention has been given to the target samples and the extent to which they are able to provide meaningful information o...

Rapid atmospheric warming since the mid-twentieth century has increased temperature-dependent erosion and sediment-transport processes in cold environments, affecting food, energy and water security. In this Review, we summarize landscape changes in cold environments and provide a global inventory of increases in erosion and sediment yield driven b...

Information on both the magnitude and relative contributions of inter‐gully and gully areas to the sediment yield from small catchments in the Loess Plateau of China represents an important requirement for understanding catchment sediment dynamics, assessing the sensitivity of catchment sediment budgets to environmental change and developing effect...

Purpose Volcanic, humid tropical landscapes are characterized by short-term geomorphic transformations due to volcanism and seismic activity, landslides, and other frequent mass movements. These landscape-forming processes are amplified by high temperatures, high annual precipitation rates, and intense rainstorms. The latter can result in significa...

Global warming-induced melting and thawing of the cryosphere are severely altering the volume and timing of water supplied from High Mountain Asia, adversely affecting downstream food and energy systems that are relied on by billions of people. The construction of more reservoirs designed to regulate streamflow and produce hydropower is a critical...

The Jacuí Delta drains into Lake Guaíba which is the main source of water for more than two million people in South Brazil and has suffered from pollution with heavy metals and phosphorus. The objective of the current research is to demonstrate how the use of sediment source tracing techniques, in combination with sediment flux monitoring, can impr...

Muddied waters The climate of High Mountain Asia is becoming warmer and wetter. Li et al . present data showing that rivers originating in this region have experienced large increases in runoff and sediment fluxes over the past six decades, most dramatically since the mid-1990s. The authors project that sediment flux from those rivers could more th...

Lowland multiple-channel rivers are characterised by floodplain-corridor heterogeneity, high ecological and heritage value, and can be in quasi-stable states. This holistic study of a surviving temperate zone example (Culm, UK) uses geomorphological mapping, ¹⁴C, direct sediment dating (OSL, fallout radionuclides), and palaeoecology. This reveals t...

Vast areas of Europe were contaminated by the fallout of 137Cs and other radionuclides, as a result of the Chernobyl accident in 1986. The post-fallout redistribution of Chernobyl-derived 137Cs was associated with erosion and sediment transport processes within the fluvial system. Bottom sediments from lakes and reservoirs can provide a valuable so...

Fingerprinting techniques were incorporated into a paired catchment investigation in southern Chile to quantify the contribution of three fine sediment sources (catchment surfaces, forest roads and stream channels) to catchment suspended sediment yields during forest harvesting and replanting operations. Optimum composite fingerprints for use in se...

This article aims to provide a broad overview of the topic across spatial scales ranging from small catchments to a global perspective. The two elements of the topic (i.e. sediment yields and sediment budgets) are closely related, with the former treating the catchment or river basin essentially as a black box. The latter looks into the black box t...

Water and sediment transport from rivers to oceans is of primary importance in global geochemical cycle. Against the background of global change, this study examines the changes in water and sediment fluxes and their drivers for 4307 large rivers worldwide (basin area ≥1000 km²) based on the longest available records. Here we find that 24% of the w...

Sediment deposits in lakes and reservoirs can provide a basis for reconstructing the erosional response of the upstream catchment. Recent studies undertaken in the Loess Region of China have successfully used the flood couplets contained in the sediment deposits behind check dams to reconstruct records of annual sediment yield and document the impa...

Vast areas of Europe were contaminated by Chernobyl fallout in April-May 1986. As a result, an additional time-marker appeared in the sediment profiles of many sediment sinks, including dry valleys, river floodplain, lakes and reservoirs. Recently, both bomb-derived and Chernobyl-derived 137Cs have been used to reconstruct sedimentation rates for t...

Large-scale deforestation, intensive land use and unfavourable rainfall conditions are responsible for significant continuous degradation of the Haitian uplands. To develop soil conservation strategies, simple and cost-effective methods are needed to assess rates of soil loss from farmland in Haiti. The fallout radionuclide caesium-137 (137Cs) prov...

Management of sediment in river basins and waterways has been an important issue for water managers throughout history. The changing nature of sediment issues has meant that water managers today face many complex technical and environmental challenges in relation to sediment management. UNESCO's International Hydrological Programme (IHP) launched t...

Check dams are one of the most important engineering measures for controlling soil and water loss from watersheds and can play a key role in reducing sediment loads in rivers. In addition, the associated sediment deposits can in some circumstances provide a valuable source of information on changing rates of sediment production from the upstream wa...

Fallout caesium-137 has been used to trace soil redistribution in abandoned fields located in the Central Spanish Pyrenees. A total of 28 fields with different lengths, slope angles and time since abandonment were selected on a representative south facing slope of the Estarrún valley. The local reference inventory and the magnitude and spatial dist...

PurposeThe particle size distributions (PSDs) of soil and associated sediment are of fundamental importance in studying soil erosion dynamics and related environmental issues. However, detailed information on the variation of sediment size distributions within the erosion-delivery continuum and the effects of particle size selectivity on the size d...

In recent years, the fallout radionuclides caesium-137 ((137)Cs) and unsupported lead-210 ((210)Pbex) have been successfully used to document rates of soil erosion in many areas of the world, as an alternative to conventional measurements. By virtue of their different half-lives, these two radionuclides are capable of providing information related...

The need for reliable assessments of soil erosion rates in Serbia has directed attention to the potential for using (137)Cs measurements to derive estimates of soil redistribution rates. Since, to date, this approach has not been applied in southeastern Serbia, a reconnaissance study was undertaken to confirm its viability. The need to take account...

Recent advances in sediment source tracing or fingerprinting procedures have focussed primarily on the use of novel sediment properties that are either easier to measure or provide improved source discrimination, or on improved procedures for representing and estimating the uncertainty associated with the final source apportionment results. Spatial...

Use of the fallout radionuclides cesium-137 and excess lead-210 offers important advantages over traditional methods of quantifying erosion and soil redistribution rates. However, both radionuclides provide information on longer-term (i.e., 50-100 years) average rates of soil redistribution. Beryllium-7, with its half-life of 53 days, can provide a...

This chapter focuses on the measurements (the tools), namely gamma-emitting radionuclides, environmental magnetism and sediment geochemistry. By studying the post-fallout redistribution and fate of these fallout radionuclides, it is possible to obtain essentially unique information on soil and sediment redistribution and, therefore, on erosion and...

This chapter considers the key concepts to develop an improved understanding of the fine sediment loads of rivers. The key concepts are non-capacity and supply-controlled nature of fine sediment transport, the significance of grain size, sediment composition and composite particles, the importance of sediment source and the need to view the fine se...

The sediment budget is a key concept and tool for characterizing the mobilization, transfer and storage of fine sediment within a catchment. Caesium-137 measurements can provide valuable information on gross and net erosion rates associated with sheet and rill erosion that can be used to establish the slope component of a catchment sediment budget....

A long-term measurement programme was operated in southern Italy during the 1960s and 1970s, to provide information on the suspended sediment yields from the main river basins. Information obtained for the rivers of Calabria suggests that suspended sediment yields in this area are relatively low. However, there is evidence that the intensity of lan...

Information on rates of overbank sedimentation on river floodplains is needed for a variety of purposes. Use of 137 Cs and 210 Pbex measurements provides an effective means of estimating medium-term floodplain sedimentation rates and that approach has now been successfully used in many areas of the world. This contribution reviews the use of 137 Cs...

The rapid expansion of agriculture in Brazil has increased erosion rates and sediment yields, causing many negative environmental and economic impacts, both on- and off-site. However, to date, very few catchment-scale sediment budget investigations have been carried out in Brazil. Given the need to reduce the negative off-site impacts of increasing...

The techniques available for documenting rates and patterns of soil redistribution in the landscape have many limitations and the value of those employing fallout radionuclides (FRNs), including caesium-137 (137Cs) and excess lead-210 (210Pbex) is being increasingly recognised. However, the use of 137Cs and 210Pbex measurements is best suited to in...

The application of fallout radionuclides in soil erosion investigations and related sediment budget studies has provided a widely used tool for improving understanding of soil erosion and sediment transfer processes. However, most studies using fallout radionuclides undertaken to date have focussed on small areas. This focus on small areas reflects...

Increasing anthropogenic pressures coupled with climate change impacts on natural resources have promoted a quest for innovative tracing techniques for understanding soil redistribution processes and assessing the environmental status of soil resources. Among the different existing tracers, the fallout component of the radioisotope lead-210, also t...

NB = The full book (i.e. IAEA-TECDOC-1741) is available for free, please see: http://www-pub.iaea.org/books/IAEABooks/10501/Guidelines-for-Using-Fallout-Radionuclides-to-Assess-Erosion-and-Effectiveness-of-Soil-Conservation-Strategies-

NB = The full book (i.e. IAEA-TECDOC-1741) is available for free, please see: http://www-pub.iaea.org/books/IAEABooks/10501/Guidelines-for-Using-Fallout-Radionuclides-to-Assess-Erosion-and-Effectiveness-of-Soil-Conservation-Strategies-

NB = The full book (i.e. IAEA-TECDOC-1741) is available for free, please see: http://www-pub.iaea.org/books/IAEABooks/10501/Guidelines-for-Using-Fallout-Radionuclides-to-Assess-Erosion-and-Effectiveness-of-Soil-Conservation-Strategies-

NB = The full book (i.e. IAEA-TECDOC-1741) is available for free, please see: http://www-pub.iaea.org/books/IAEABooks/10501/Guidelines-for-Using-Fallout-Radionuclides-to-Assess-Erosion-and-Effectiveness-of-Soil-Conservation-Strategies-

NB = The full book (i.e. IAEA-TECDOC-1741) is available for free, please see: http://www-pub.iaea.org/books/IAEABooks/10501/Guidelines-for-Using-Fallout-Radionuclides-to-Assess-Erosion-and-Effectiveness-of-Soil-Conservation-Strategies-

Soil erosion has become a serious environmental problem in southern Italy, where annual soil loss associated with extreme rainfall events can reach 100-150 t ha-1. In order to predict rates of soil loss and sediment yields, to inform the development of effective erosion and sediment control strategies in these areas, several prediction models have...

River floodplains act as sinks for fine-sediment and sediment-associated contaminants. Increasing recognition of their environmental importance has necessitated a need for an improved understanding of the fate and residence times of overbank sediment deposits over a broad range of timescales. Most existing investigations have focused on medium-term...

Rapid and reliable methods for estimating the relative contribution of interrill and rill erosion during a rainfall event are needed to provide an improved understanding of soil erosion processes and to develop process-based soil erosion prediction models. Use of the radionuclide 7Be in controlled experiments provides a means of addressing this nee...

Recent synthesis of 10Be-derived denudation rates by [Willenbring et al. (2013)][1] suggests that the “flat” areas of the world, those with average slopes of <∼100 m/km and representing ∼90% of Earth’s land surface, have adequately high rates of denudation to produce most of the sediment

Purpose This contribution reviews the evolution of sediment source fingerprinting investigations since the beginning of such studies in the mid-1970s. Attention is directed to key advances and developments during this period, to the present status of source fingerprinting techniques and to the scope for future development. Scope An analysis of the...

Sandy loess from the Wind–Water Erosion Crisscross Region on the Loess Plateau of China, an area with severe wind erosion, was collected for use in a wind tunnel experiment, to explore the feasibility of using 7Be measurements to estimate the amount of soil lost through wind erosion. Wind erosion selectively removes the finer particles of soil. Use...

A study of the impact of forest harvesting operations on sediment mobilization from forested catchments has been undertaken in south-central Chile. The study focused on two sets of small paired catchments (treatment and control), with similar soil type, but contrasting mean annual rainfall, located about 400 km apart at Nacimiento (1200 mm yr(-1))...

Information on soil redistribution rates associated with the intricate patterns of Mediterranean agroecosystems is a key requirement for assessing both soil degradation, and off-site sediment problems that can affect downstream water bodies. Excess lead-210 (210Pbex) measurements provide a very effective means of documenting spatial patterns of rat...

The Baurières plain within the upper Drôme River basin was used to reconstruct recent changes in sediment supply in relation to changes in land use within an alpine catchment. A considerable body of archival information is available. Furthermore, the plain acts as a natural sediment trap and the reach–basin interaction has not been disrupted by hum...

Changes in the sediment load of a river can have important impacts on river channel evolution, nutrient fluxes, aquatic ecology and delta erosion and sedimentation, and the possibility of changes in the sediment load of the Lancang-Mekong River has attracted increasing concern in recent years. Existing studies present conflicting findings regarding...

Current concern for the sustainable management of soil resources and the many adverse effects of increased sediment loads on streams and river systems has generated a need for more information on rates and patterns of soil loss and an improved understanding of catchment sediment budgets. Traditional measurement techniques are frequently unable to m...

Although traditional sediment tracing approaches provide valuable information for characterising key generic sediment sources, Catchment Officers working as part of the Catchment Sensitive Farming initiative frequently require more detailed evidence to permit improved targeting of mitigation. Accordingly, a novel framework combining conventional se...

Concern for the sustainability of the soil resource and for the detrimental impacts of fine sediment on downstream river systems and aquatic ecosystems has directed attention to the need for information on the suspended sediment loads of rivers. However, traditional measurement programmes focus primarily on quantifying the sediment load at a catchm...

Predicting the expected life of a reservoir and assessing the potential for increasing this life is a great challenge for the hydraulic engineer, as it involves predicting the sediment input to the reservoir. The rate of sedimentation in a reservoir will primarily reflect the amount of sediment eroded from the upstream catchment and the efficiency...

The world's deltas currently face many important threats to their longer term stability. Subsidence and sea level rise are key problems and their potential impact is strongly influenced by changes in sediment supply. Fluvial sediment inputs exert a key control on delta evolution and stability, as well as providing an important source of nutrients t...

Information on the nature and relative contribution of different watershed sediment sources is recognized as a key requirement in the design and implementation of targeted management strategies for sediment control. A direct method of assessing sediment sources in a watershed that has attracted attention in recent years is sediment fingerprinting....

The pathway that delivers mobilized phosphorus (P) from source to surface water is conceptually complex. Firstly P mobilization itself, either through mechanical disturbance of the soil, or through chemical dissolution or weathering is difficult to measure in situ, secondly the annual flow weighted mean concentration of P is a difficult metric to g...

Extensive rainfed herbaceous crops are one of the most representative agricultural elements of Mediterranean region, which should be one of the major factors affecting erosion processes. Although land use is commonly seen as resulting in increased sediment yields, the implementation of soil and water conservation practices can have the reverse effe...

Increasing recognition of the deleterious environmental effects of excessive fine sediment delivery to watercourses means that reliable sediment source assessment represents a fundamental component of catchment planning targeting the protection of freshwater resources and their ecological integrity. Sediment tracing or fingerprinting approaches hav...

Soil erosion represents an important threat to the long-term sustainability of agriculture and forestry in many areas of the world, including southern Italy. Numerous models and prediction procedures have been developed to estimate rates of soil loss and soil redistribution, based on the local topography, hydrometeorology, soil type and land manage...

A study to improve the understanding of the primary sediment sources and transfer pathways in catchments disturbed following forest plantation harvesting is being undertaken in South-Central Chile. The study focuses on two sets of paired experimental catchments (treatment and control), located about 400 km apart, with similar soil type but contrast...

This paper summarizes key findings and identifies the main lessons learnt from a 5-year (2002-2008) coordinated research project (CRP) on “Assessing the effectiveness of soil conservation measures for sustainable watershed management and crop production using fallout radionuclides” (D1.50.08), organized and funded by the International Atomic Energy...

A Compound Specific Stable Isotope (CSSI) sediment tracing approach is evaluated for the first time in an agricultural catchment setting against established geochemical fingerprinting techniques. The work demonstrates that novel CSSI techniques have the potential to provide important support for soil resource management policies and inform sediment...

Growing interest in the dynamics of floodplain evolution and the important role of overbank sedimentation on river floodplains as a sediment sink has focused attention on the need to document contemporary and recent rates of overbank sedimentation. The potential for using the fallout radionuclides ¹³⁷Cs and excess ²¹⁰Pb to estimate medium-term (10-...

Definition of the SubjectSoil erosion is an important problem in many areas of the world, where it reduces soil productivity, destroys agricultural land, and can threaten food security and the sustainable management of soil resources. The on-site effects of soil erosion are coupled with off-site effects, which relate to the downstream or downwind i...

Fine sediment (particles <63 μm) carried by the Helford River was investigated in 16 sub-catchments above the tidal limit for the period 1 June 2005 to 31 May 2006. Equipment for continuous monitoring of turbidity and river stage (height) was installed in the six largest tributaries and revealed the importance of storm events and the dominance of w...

The rapid expansion of agriculture in Brazil has increased erosion rates and sediment yields, causing many negative environmental and economic impacts. Given the need to reduce the negative impacts, there is an important need for studies that assess the response of catchment sediment dynamics and budgets to soil and water conservation practices. 13...

Dams and their associated reservoirs are a key element of water resource development in most areas of the world and dams have been constructed on many of the world's large rivers. The presence of dams causes sedimentation in the upstream reservoir and such sediment trapping can exert an important influence in reducing downstream sediment transport....

Information on rates of soil loss and associated rates of soil redistribution are seen as an important requirement for effective environmental management. The use of the fallout radionuclides caesium-137 (137Cs) and excess lead-210 (210Vbex) to document rates of soil and sediment redistribution in the landscape has attracted increasing attention in...

This chapter reviews the recent development and status of work in the field of erosion and sediment yield. It highlights the growing importance of sediment as an environmental problem and associated changes in emphasis of work in this field, including increased interest in sediment quality. The central importance of the sediment budget concept is i...

Samples of suspended and fine channel bed sediment were used to examine the spatial and temporal variability in the amount of fine-grained sediment and associated contaminants temporarily stored in the Na Borges River (319 km(2)) in Mallorca and the relationship of such channel storage to the fluxes of fine sediment and associated contaminant throu...

Catchment erosion, soil losses and resulting sediment pressures continue to represent cause for concern with respect to the ecological vitality and amenity value of riverine systems, including those in the agricultural catchments of southern England. Given that the sources of fine-grained sediment are typically diffuse in nature, it is essential to...

Information on the interaction between soil erosion and soil properties is an important requirement for sustainable management of the soil resource. The relationship between soil properties and the soil redistribution rate, reflecting both erosion and deposition, is an important indicator of this interaction. This relationship is difficult to inves...

Growing awareness of the wider environmental significance of fine sediment transport by rivers and associated sediment problems linked to sediment–water quality interactions, nutrient and contaminant transfer, and the degradation of aquatic habitats has resulted in the need for an improved understanding of the mobilization and transfer of sediment...

Information on the interaction between soil erosion and soil properties is an important requirement for sustainable management of the soil resource. The relationship between soil properties and the soil redistribution rate, reflecting both erosion and deposition, is an important indicator of this interaction. This relationship is difficult to inves...

Increasing risk of soil loss as a result of climate change, has generated a need for reliable information on erosion rates at different temporal scales. Use of the fallout radionuclides 137Cs, 210Pbex and 7Be as tracers of sediment mobilization and redistribution makes it possible to obtain estimates of soil redistribution rates within both undistu...

Management strategies that focus on stream and watershed restoration with the goal of reducing erosion and sediment flux should be founded on a sound understanding of the sediment sources contributing to the sediment flux and the overall sediment budget of the watershed in question. This understanding can be provided by undertaking complementary se...

A warming climate increases tropical cyclone intensity, causing more intense rainfall. This creates problems for soil and water conservation and management, particularly for countries in the western tropical-subtropical Pacific region, where cyclones (typhoons) frequently occur. Taiwan is located on a typhoon track and frequently suffers from devas...