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The reformed Common Agricultural Policy of 2023-2027 aims to promote a more sustainable and fair agricultural system in the European Union. Among the proposed measures, the incentivized adoption of cover crops to cover the soil during winter provides numerous benefits such as improved soil structure and reduced nutrient leaching and erosion. Despite this recognized importance, the availability of spatial data on cover crops is scarce. The increasing availability of field parcel declarations in the European Union has not yet filled this data gap due to its insufficient information content, limited public availability and a lack of standardization at continental scale. At present, the best information available is regionally aggregated survey data, which although indicative, hinders the development of spatially accurate studies. In this work, we propose a statistical model relating Sentinel-1 data to the existence of cover crops at the 100-m spatial resolution over the entirety of the European Union and United Kingdom and estimate its parameters using the spatially aggregated survey data. To validate the method in a spatially-explicit way, predictions were compared against farmers' registered declarations in France, where the adoption of cover crops is widespread. The results indicate a good agreement between predictions and parcel-level data. When interpreted as a binary classifier, the model yielded an Area Under the Curve (AUC) of 0.74 for the whole country. When the country was divided into five regions for the evaluation of regional biases, the AUC values were 0.77, 0.75, 0.74, 0.70, and 0.65 for the North, Center, West, East, and South regions respectively. Despite limitations such as the lack of data for validation outside France, and the non-standardized nomenclature for cover crops among Member States, this work constitutes the first effort to obtain a relevant cover crop map at a European scale for researchers and practitioners. ispartof: SCIENCE OF THE TOTAL ENVIRONMENT vol:873 ispartof: location:Netherlands status: published

ispartof: INTERNATIONAL SOIL AND WATER CONSERVATION RESEARCH vol:11 issue:1 pages:43-59 status: accepted

Sustainable land management (SLM) is widely recognized as the key to reducing rates of land degradation, and preventing desertification. Many efforts have been made worldwide by various stakeholders to adopt and/or develop various SLM practices. Nevertheless, a comprehensive review on the spatial distribution, prospects, and challenges of SLM practices and research is lacking. To address this gap, we gathered information from a global SLM database provided by the World Overview of Conservation Approaches and Technologies (WOCAT) and two bibliographic databases of academic research. Over 1900 SLM practices and 1181 academic research papers from 129 and 90 countries were compiled and analyzed. Relatively better SLM dissemination was observed in dry subhumid countries and countries with medium scores on the Human Development Index (HDI), whereas dissemination and research were both lower in humid countries with low HDI values. Cropland was the main land use type targeted in both dissemination and research; degradation caused by water erosion and mitigation aimed at water erosion were also the main focus areas. Other dominant land use types (e.g., grazing) and SLM purposes (e.g., economic benefits) have received relatively less research attention compared to their dissemination. Overall, over 75 % of the 60 countries experiencing high soil erosion rates (>10 t ha-1 yr-1) also have low HDI scores, as well as poor SLM dissemination and research implying the limited evidence-based SLM dissemination in these countries. The limitation of research evidence can be addressed in the short term through integrating existing scientific research and SLM databases by adopting the proposed Research Evidence for SLM framework. There is, however, a great need for additional detailed studies of country-specific SLM challenges and prospects to create appropriate evidence-based SLM dissemination strategies to achieve multiple SLM benefits. ispartof: SCIENCE OF THE TOTAL ENVIRONMENT vol:858 issue:Pt 3 ispartof: location:Netherlands status: published

ispartof: EARTH SURFACE PROCESSES AND LANDFORMS vol:47 issue:15 pages:3558-3587 status: published

The erosive force of rainfall (rainfall erosivity) is a major driver of soil, nutrient losses worldwide and an important input for soil erosion assessments models. Here, we present a comprehensive set of future erosivity projections at a 30 arc-second (∼1 km2) spatial scale using 19 downscaled General Circulation Models (GCMs) simulating three Representative Concentration Pathways (RCPs) for the periods 2041–2060 and 2061–2080. The future rainfall erosivity projections were obtained based on a Gaussian Process Regression (GPR) approach relating rainfall depth to rainfall erosivity through a series of (bio)climatic covariates. Compared to the 2010 Global Rainfall erosivity baseline, we estimate a potential average increase in global rainfall erosivity between 26.2 and 28.8% for 2050 and 27–34.3% for 2070. Therefore, climate change and the consequential increase in rainfall erosivity is the main driver of the projected + 30–66% increase in soil erosion rates by 2070. Our results were successfully compared with 20 regional studies addressing the rainfall erosivity projections. We release the whole dataset of future rainfall erosivity projections composed of 102 simulation scenarios, with the aim to support further research activities on soil erosion, soil conservation and climate change communities. We expect these datasets to address the needs of both the Earth system modeling community and policy makers. In addition, we introduce a modeling approach to estimate future erosivity and make further assessments at global and continental scales.

To date, most regional and global hydrological models either ignore the representation of cropland or consider crop cultivation in a simplistic way or in abstract terms without any management practices. Yet, the water balance of cultivated areas is strongly influenced by applied management practices (e.g. planting, irrigation, fertilization, and harvesting). The SWAT+ (Soil and Water Assessment Tool) model represents agricultural land by default in a generic way, where the start of the cropping season is driven by accumulated heat units. However, this approach does not work for tropical and subtropical regions such as sub-Saharan Africa, where crop growth dynamics are mainly controlled by rainfall rather than temperature. In this study, we present an approach on how to incorporate crop phenology using decision tables and global datasets of rainfed and irrigated croplands with the associated cropping calendar and fertilizer applications in a regional SWAT+ model for northeastern Africa. We evaluate the influence of the crop phenology representation on simulations of leaf area index (LAI) and evapotranspiration (ET) using LAI remote sensing data from Copernicus Global Land Service (CGLS) and WaPOR (Water Productivity through Open access of Remotely sensed derived data) ET data, respectively. Results show that a representation of crop phenology using global datasets leads to improved temporal patterns of LAI and ET simulations, especially for regions with a single cropping cycle. However, for regions with multiple cropping seasons, global phenology datasets need to be complemented with local data or remote sensing data to capture additional cropping seasons. In addition, the improvement of the cropping season also helps to improve soil erosion estimates, as the timing of crop cover controls erosion rates in the model. With more realistic growing seasons, soil erosion is largely reduced for most agricultural hydrologic response units (HRUs), which can be considered as a move towards substantial improvements over previous estimates. We conclude that regional and global hydrological models can benefit from improved representations of crop phenology and the associated management practices. Future work regarding the incorporation of multiple cropping seasons in global phenology data is needed to better represent cropping cycles in areas where they occur using regional to global hydrological models.

International audience; Land degradation due to soil erosion presents a major challenge for sustainable development. We investigated run-off and sediment yield (SY) dynamics in the northwestern highlands of Ethiopia. The study area included 14 zero-order catchments with a surface area ranging from 324 to 1715 m2. V-notch weirs produced from plastic jars were introduced as measuring alternatives that met local constraints. Run-off (RO) depth at the weir was registered manually at 5-min intervals during two rainy seasons in 2018 and 2019, and a total of 618 events were monitored. Rainfall was measured using tipping-bucket rain gauges. RO samples were collected in 1-L bottles, and suspended sediment concentration was determined. The mean event RO coefficient ranged from 3% for forests to 56% for badlands. Similarly, the mean annual SY was lowest for forests (0.8 Mg ha−1 yr−1) and highest for badlands (43.4 Mg ha−1 yr−1), with significant differences among land-use types (14.8 Mg ha−1 yr−1 in cropland, 5.7 Mg ha−1 yr−1 in grazing land, and 2.9 Mg ha−1 yr−1 in plantations). Soil organic matter (SOM) reduced RO and SY, necessitating the consideration of agronomic and land management practices that enhance SOM. Annual SY decreased exponentially with the rock fragment cover (RFC). In fields where RFC was less than 20%, collecting rock fragments for installing stone bunds resulted in a net increase in SY. Rehabilitating badlands and enhancing SOM content in croplands can substantially reduce catchment SY and hence contribute to the sustainability of land uses in the subhumid highlands.

The present study was conducted to determine the areas and volumes of erosion zones in Thrace peninsula using geographical information systems (GIS). Measurements made with remote sensing both save time and prevent excess workforce. In addition, it is less costly than satellite images that can be purchased for areas where drones can be shot. For this purpose, 13 erosion sites with different environmental characteristics were examined and images were obtained with an unmanned aerial vehicle (UAV) in the study area. To calibrate the UAV data, the boundaries were determined using nature-friendly white paint. Then, all measurements (lengths, angles, etc.) of these areas were calculated from various altitudes. Volume of the determined areas then processed using GIS software and a graphic program named "Autodesk Inventor". All of the UAV tasks were taken under suitable weather condition in order to avoid any difference in the images. Furher, the UAV images to be combined were obtained under similar weather conditions to ensure that factors such as light and shadow do not cause any deviation in the calculations and create visual differences. Images were taken from a total of 13 erosion areas and WGS 1984 (World Geodetic System 1984) was used as the coordinate system in the present study.Orthomosaic images of these areas were created by combining the images. In addition to the areas and volumes of the regions in the images, calibration analyzes were also made. Using a small area for calibration in the study increased the accuracy of area measurement rate above 90%, while this rate was found between 60 - 78% in volume measurement depending on the flight altitude. 12 photos were used in the image taken from a height of 100 meters and 103 from a height of 10 meters in the calibration from approximately 100 m2. Accordingly, the volumetric accuracy rate was found to be 78.57% in the image taken from a height of 10 meters from the ground., Bu çalışma, Trakya Yarımadası’nda tespit edilen erozyon bölgelerinin alan ve hacimlerinin Coğrafi Bilgi Sistemleri (CBS) kullanılarak hesaplanması amacı ile gerçekleştirilmiştir. Uzaktan algılama ile yapılan ölçümler hem zaman kazanımı hem de fazla işgücünün önüne geçmektedir. Ayrıca drone ile çekim yapılabilecek araziler için satın alınabilecek uydu görüntülerinden daha az maliyetli olmaktadır. Bu amaçla, bölgede doğal karakteristikleri farklılık gösteren 13 erozyon alanı incelenmiş ve insansız hava aracı (drone) ile görüntüler elde edilmiştir. Çalışmada İHA verilerinin kalibrasyonu amacıyla sınırları belli olan ve doğaya zarar vermeyen beyaz boya ile sınırları belirlenmiş ve çeşitli yüksekliklerden bu alanların tüm ölçümleri (uzunluklar, açılar vb.) yapılmıştır. Sınırları belirlenen alanlar daha sonra İHA görüntüleri alınarak CBS yazılımları ve grafik programı “Autodesk Inventor” ile çeşitli proseslerden geçirilerek hacim hesaplaması yapılmıştır. Görüntülerde farklılık olmaması için uygun hava koşulları beklenmiş ve birleştirilecek olan İHA görüntüleri benzer hava şartlarında elde edilmiştir. Farklı hava koşullarında alınan görüntülerin birleştirilmesinde ışık, gölge gibi faktörlerin hesaplamalarda herhangi bir sapmaya neden olmaması ve görsel olarak farklılık oluşturmaması için özen gösterilmiştir. Toplam 13 adet erozyon alanlarından görüntüler alınmış ve çalışmada koordinat sistemi olarak WGS 1984 (World Geodetic System 1984) kullanılmıştır.Bu görüntüler birleştirilerek bu alanların ortomozaik görüntüleri oluşturulmuştur. Görüntülerdeki bölgelerin alan ve hacimlerinin yanı sıra kalibrasyonları da yapılmıştır. Yapılan çalışmada, kalibrasyon için küçük bir alanın kullanılması alansal hesaplamada doğruluk oranını %90’ın üzerine çıkarırken hacim ölçümlerinde ise bu oran uçuş yüksekliğine göre %60 – 78 arasında bulunmuştur. Yaklaşık 100 m2 alanda yapılan kalibrasyon çalışmasında 100 metre yükseklikten çekilen görüntüde 12 fotoğraf, 10 metre yükseklikten çekilen görüntüde ise 103 fotoğraf kullanılmıştır. Buna göre, yerden 10 metre yükseklikten çekilen görüntüde hacimsel doğruluk oranı %78,57 bulunmuştur.

Desertification is influenced by different factors that relate to climate, soil, topography, geology, vegetation, human pressure, and land and water management. The quantification of these factors into spatially explicit indicators and subsequent evaluation provides for a framework that allows us to identify areas currently at risk of desertification and to evaluate important contributing biophysical and socio-economic factors. Based on local knowledge of environmental contributing factors to the risk of desertification in the Binh Thuan Province of southeast Vietnam, a baseline 2010 map showed that 14.4 % of the area, mainly along the coast and in the northeast, is desertified with another 35.4 % at severe risk of desertification. The Vietnamese Ministry of Natural Resource and Environment has defined the area with a ratio of rainfall to evapotranspiration smaller or equal to 0.65, which equals 1233 km2 or 15 % of the province, as desertified area, which corresponds well with the baseline 2010 map. The developed framework incorporates the important contributing factors and therefore allows for decision support in a “what if” structure and for the projection of potentially vulnerable areas under future scenarios. With projected climate change and population growth, the desertified area is expected to increase by 122 % (or 137 850 ha) towards 2050. The developed methodology can be extended to neighbouring provinces that experience similar sensitivities to desertification.

This study focuses on the Kuibyshev reservoir (Volga River basin, Russia)—the largest in Eurasia and the third in the world by area (6150 km2). The objective of this paper is to quantitatively assess the dynamics of reservoir bank landslides and shoreline abrasion at active zones based on the integrated use of modern instrumental methods (i.e., terrestrial laser scanning—TLS, unmanned aerial vehicle—UAV, and a global navigation satellite system—GNSS) and GIS analysis of historical imagery. A methodology for the application of different methods of instrumental assessment of abrasion and landslide processes is developed. Different approaches are used to assess the intensity of landslide and abrasion processes: the specific volume and material loss index, the planar displacement of the bank scarp, and the planar-altitude analysis of displaced soil material based on the analysis of slope profiles. Historical shoreline position (1958, 1985, and 1987) was obtained from archival aerial photo data, whereas data for 1975, 1993, 2010, 2011, and 2012 were obtained from high-resolution satellite image interpretation. Field surveys of the geomorphic processes from 2002, 2003, 2005, 2006, 2014 were carried out using Trimble M3 and Trimble VX total stations; in 2012–2014 and 2019 TLS and UAV surveys were made, respectively. The monitoring of landslide processes showed that the rate of volumetric changes at Site 1 remained rather stable during the measurement period with net material losses of 0.03–0.04 m−3 m−2 yr−1. The most significant contribution to the average annual value of the material loss was snowmelt runoff. The landslide scarp retreat rate at Site 2 showed a steady decreasing trend, due to partial overgrowth of the landslide accumulation zone resulting in its relative stabilization. The average long-term landslide scarp retreat rate is—2.3 m yr−1. In 2019 earthworks for landscaping at this site have reduced the landslide intensity by more than 2.5 times to—0.84 m yr−1.

Most contemporary crop yield models focus on a small time window, operate on a plot location, or do not include the effects of the changing environment, which makes it difficult to use these models to assess the agricultural sustainability for past societies. In this study, adaptions were made to the agronomic AquaCrop model. This adapted model was ran to cover the last 4000 years to simulate the impact of climate and land cover changes, as well as soil dynamics, on the productivity of winter wheat crops for a Mediterranean mountain environment in SW Turkey. AquaCrop has been made spatially explicit, which allows hydrological interactions between different landscape positions, whilst computational time is kept limited by implementing parallelisation schemes on a supercomputer. The adapted model was calibrated and validated using crop and soil information sampled during the 2015 and 2016 harvest periods. Simulated crop yields for the last 4000 years show the strong control of precipitation, while changes in soil thickness following erosion, and to lesser extent re-infiltration of runoff along a slope catena also have a significant impact on crop yield. The latter is especially important in the valleys, where soil and water accumulate. The model results also show that water export to the central valley strongly increased (up to four times) following deforestation and the resulting soil erosion on the hillslopes, turning it into a marsh and rendering it unsuitable for crop cultivation.

This paper presents all current knowledge on the biology of the invasive therophyte Impatiens glandulifera Royle (Himalayan Balsam), and covers aspects of taxonomy, morphology, distribution, habitat requirements, ecology, life cycle, genetics, history of invasive spread, ecological impact and management. Although a few review papers have been published on this species in previous decades, a great deal of insights have been gained in the last three decades, owing to the species’ notorious reputation as one of the most problematic invasive species in Europe. This study consequently focusses on this novel information, with a particular focus on information from Central Europe.

© 2019 The Author(s) Gully erosion is one of the main causes of land degradation, particularly in the drought-prone regions of Ethiopia. This study assessed spatio-temporal changes of gully length and density in watershed pairs in Guder, Aba Gerima, and Dibatie sites, which are representative highland, midland, and lowland agro-ecologies in the Upper Blue Nile basin of Ethiopia. Aerial photographs (1957, 1982) and very high resolution satellite images (QuickBird, IKONOS, Worldview-2, SPOT-7, and Pleiades) of the six watersheds, along with field survey results, were used in the analyses. The aerial photographs were scanned and orthorectified using ENVI 4.3 image analysis software, and gullies were mapped by visual image interpretation in the ArcGIS environment. Rates of increase in gully length in Guder (36.9 m yr −1 ) and Aba Gerima (33.6 m yr −1 ) were almost double the rate in Dibatie (17.8 m yr −1 ) from 1957 to 2016 or 2017, and over the same period, gully density similarly increased by 5.9, 5.4, and 3.7 m ha −1 in Guder, Aba Gerima, and Dibatie, respectively. The higher rates in Guder and Aba Gerima reflect the long history of cultivation and human settlement in those sites, whereas agricultural activity became widespread in Dibatie only after implementation of the national resettlement program in the 1980s. Moreover, although gully density tended to increase over time in all six watersheds, in the three watersheds (one in each paired watershed) where soil and water conservation measures had been introduced, the rate of increase was lower than in those where no such measures were implemented. In addition, gully distribution was linked to land use and landscape position; gully density was higher in cultivated areas and where slope gradients were gentle. The results of this study indicate that careful site-specific identification of factors controlling gully initiation and development is crucial so that appropriate management strategies can be developed for these three sites and for other areas with similar agro-ecologies in the Upper Blue Nile basin. ispartof: CATENA vol:179 pages:160-174 status: published

This paper aims to reconstruct Middle Bronze Age (MBA; 1600–1250 BCE) land use practices in the northwestern Alpine foreland (SW Germany, Hegau). We used a multi-proxy approach including the analysis of biogeochemical proxies from colluvial deposits and buried topsoils in the surroundings of the well-documented settlement site of Anselfingen and off-site pollen data from two peat bogs. This approach allowed for in-depth insights into the MBA subsistence economy and shows that the MBA in the northwestern Alpine foreland was a period of establishing settlements with sophisticated land management and land use practices. The reconstruction of phases of colluvial deposition was based on ages from optically stimulated luminescence (OSL) and radiocarbon (AMS14C) dating from multi-layered colluvial deposits and supports the local archaeological record with the first phase of major colluvial deposition occurring during the MBA followed by phases of colluvial deposition during the Iron Age, the Medieval period and modern times. The on-site deposition of charred archaeobotanical remains and animal bones from archaeological features, as well as polycyclic aromatic hydrocarbons (PAHs), charcoal spectra, phytoliths, soil microstructure, urease enzymatic activity, microbial biomass carbon (Cmic) and heavy metal contents from colluvial deposits, were used as proxies for on-site and near-site land use practices. The charcoal spectra indicate MBA forest management which favored the dominance of Quercus in the woodland vegetation in the surrounding area north of the settlement site. Increased levels of 5β stanols (up to 40 %) and the occurrence of pig bones (up to 14 %) support the presence of a forest pasture mainly used for pig farming. In the surrounding area south of the settlement, an arable field with a buried MBA plow horizon (2Apb) could be verified by soil micromorphological investigations and high concentrations of grass phytoliths from leaves and stems. Agricultural practices (e.g., plowing) focussed on five staple crops (Hordeum distichon/vulgare, Triticum dicoccum, Triticum monococcum, Triticum spelta, Triticum aestivum/turgidum), while the presence of stilted pantries as storage facilities and of heat stones indicate post-harvest processing of cereal crops and other agrarian products within the settlement. In the area surrounding the settlement, increased levels of urease activity, compared to microbial biomass carbon (up to 2.1 µg N µg Cmic-1), and input of herbivorous and omnivorous animal faeces indicate livestock husbandry on fallow land. The PAH suites and their spatial distribution support the use of fire for various purposes, e.g., for opening and maintaining the landscape, for domestic burning and for technical applications. The off-site palynological data support the observed change in on-site and near-site vegetation as well as the occurrence of related land use practices. During the Early and Middle Bronze Age, fire played a major role in shaping the landscape (peak of micro-charcoal during the MBA), and anthropogenic activities promoted Quercus-dominated forest ecosystems at the expense of natural beech forests. This indicates a broader regional human influence in the northwestern Alpine foreland at low- and mid-altitude inland sites during the Middle Bronze Age.

Gully erosion is a major environmental problem, posing significant threats to sustainable development. However, insights on techniques to prevent and control gullying are scattered and incomplete, especially regarding failure rates and effectiveness. This review aims to address these issues and contribute to more successful gully prevention and control strategies by synthesizing the data from earlier studies. Preventing gully formation can be done through land use change, applying soil and water conservation techniques or by targeted measures in concentrated flow zones. The latter include measures that increase topsoil resistance and vegetation barriers. Vegetation barriers made of plant residues have the advantage of being immediately effective in protecting against erosion, but have a short life expectancy as compared to barriers made of living vegetation. Once deeply incised, the development of gullies may be controlled by diverting runoff away from the channel, but this comes at the risk of relocating the problem. Additional measures such as headcut filling, channel reshaping and headcut armouring can also be applied. To control gully channels, multiple studies report on the use of check dams and/or vegetation. Reasons for failures of these techniques depend on runoff and sediment characteristics and cross-sectional stability and micro-environment of the gully. In turn, these are controlled by external forcing factors that can be grouped into (i) geomorphology and topography, (ii) climate and (iii) the bio-physical environment. The impact of gully prevention and control techniques is addressed, especially regarding their effect on headcut retreat and network development, the trapping of sediment by check dams and reduction of catchment sediment yield. Overall, vegetation establishment in gully channels and catchments plays a key role in gully prevention and control. Once stabilized, gullies may turn into rehabilitated sites of lush vegetation or cropland, making the return on investment to prevent and control gullies high. (c) 2020 John Wiley & Sons, Ltd.

International audience; Study Region We investigate the event runoff response in six sub-catchments in the Lake Tana sub-basin, headwater of the Blue Nile basin, northwest Ethiopia. Steep and mountainous terrains surround floodplains, imposing runoff and soil erosion in the upper catchments and flooding and sedimentation at floodplains. This study was conducted in the upland runoff source catchments. Study Focus The focus is to investigate catchment characteristics that control the event runoff response in upland catchments, and how recent land management practices may have contributed to improved hydrological conditions. Event rainfall and runoff data were obtained at five-minute time steps through automated divers and tipping bucket rain gauges and related to catchment characteristics. New Hydrological Insights for the Region Our results show that the catchment event quickflow response was controlled by different factors of both natural and anthropogenic nature of which forest and shrubs, bund density and soil organic matter content were found to be the most important to reduce event quickflow. On the contrary, increase in cropland area caused an increase in quickflow. Through least square fitting procedure of the Natural Resources Conservation Service Curve Number method (NRCS-CN), a site specific abstraction ratio (λ) value of 0.01, rather than the commonly used 0.2 or 0.05, was found to be most appropriate for the sub-humid highlands of Ethiopia.

Spatiotemporal characteristics of the trade-off among ecosystem services and its mechanism have been exten sively studied. However, studies on the difference in spatiotemporal variation of ecosystem services trade-offs in various climate zones under climate change are limited. This study aims to explore the spatiotemporal charac teristics and driving factors of trade-offs between crop production and soil conservation in different climate zones by employing a case study in various climate zones of the Shaanxi Province. We adopted statistical and GIS-based spatial analyses to explore the spatiotemporal characteristics of the trade-off and used gradient boosting decision tree to quantify the relative contribution of driving factors. Results showed that trade-off between crop pro duction and soil conservation in a middle temperate zone (0.09) is significantly lower than in a warm temperate zone (0.18) and a subtropical zone (0.21). The trade-off clearly exhibits an upward trend from 1995 to 2018 in all climate zones. However, the increasing trend gradually weakened from the middle and warm temperate zones to the subtropical zone. Moreover, changes in the trade-off are spatially heterogeneous in all climate zones. Anthropogenic activities have larger relative contribution (62.27%–71.67%) to the trade-off than environmental factors in all climate zones. Climate zone type has an insignificant effect on the relative contributions of anthropogenic activities, whereas the relative contributions of most environmental factors are significantly different in various climate zones. Fertilization (relative contribution, 26.58%–37.66%), GDP per land area (relative contribution, 8.50%–20.49%), and population density (relative contribution, 9.77%–16.11%) are the most important anthropogenic driving factors in all climate zones. The environmental factors with greatest relative contribution in the middle temperate, warm temperate, and subtropical zones are accumulated tem perature (13.40%), precipitation (26.64%), and accumulated temperature (9.63%), respectively. Thus, differ ences of spatiotemporal characteristics and driving factors of ecosystem services trade-off must be considered in the formulation of targeted polices for agroecosystem management in different climate zones.

Water erosion on agricultural land and sediment delivery to streams are a major threat to soil productivity and surface water quality. Climate change and different national and international societal drivers now require Denmark to take action to protect soil and water resources. In this study, we adapted the spatially distributed sediment transport model WaTEM using the best data available at national scale. To calibrate and validate the model, sediment yield data from 31 catchments and 189 slope units in Denmark were compared with the model output, which was produced at a fine spatial resolution of 10 × 10 m. Residual analysis and cross-validation were used to identify potential catchment outliers and assess model robustness. We obtained a median Nash & Sutcliffe model efficiency range of 0.06–0.6 for the Danish environment. Based on the equifinality concept, an ensemble of 100, NSE-weighted model realisations for acceptable transport capacity coefficients was used to assess model uncertainty. The comparison between rill survey data and predicted values indicates that although the model captures well the spatial variability in erosion, it may underestimate the long-term average of soil erosion. Based on the modelling, 71% of the agricultural land in Denmark is mapped as stable in terms of the amount of erosion and deposited material. Overall, 6.1% of the farmland is estimated to have unsustainable erosion and 0.9% of the farmland exceeds erosion rates of 7.5 t ha−1 a−1. Sediment export into surface water in Denmark equals 92,000 t a−1, corresponding to an average sediment yield of 2.7 t km−2. The performance of WaTEM is considered satisfactory in this study. Importantly, modelled water erosion exceeds the perceived erosion risk in Denmark. Strengthened by distributed uncertainty assessment at national scale, our study provides an important national knowledge base for engaging land users and regulators in the process of targeted erosion mitigation planning that is required to comply with national and EU regulation. Future investigations concerning the deviation between predicted and observed data and specific catchment parameters for the non-behavioural catchments are required as well as studies that include the establishment of catchment sediment budgets.

Land use changes, such as deforestation and agricultural expansion, increase soil erosion on the scale of hillslopes and small drainage basins. However, the effects of these changes on the sediment load in rivers is poorly quantified, with a few studies scattered globally, and only 10 data points in the world's most populous nation, China. At 20 different sites in western China, we compare contemporary fluvial sediment yield data collected daily over 4 to 26 years between 1945 and 1987 (median=19years) to long-term measures of sediment generation based on new isotopic measurements of in situ 10 Be (beryllium-10) in river sediments. We find that median sediment yield at these sites exceeds background sediment generation rates by a factor of two (from 0.13 to 5.79 times, median 1.85 times) and that contemporary sediment yield is statistically significantly different from long-term sediment generation rates (p < 0.05). Agricultural land use is directly and significantly proportional to the ratio of contemporary sediment yield to long term sediment generation rates (Spearman correlation coefficient rho=0.52, p < 0.05). We support these findings by calculating erosion indices, which compare the delivery of meteoric 10 Be to each watershed with the export of meteoric 10 Be bound to riverine sediment. Erosion indices are also directly and significantly proportional to agricultural land use (rho=0.58, p < 0.05). Together, these data sets suggest that upstream agricultural land use has significantly increased sediment supply to rivers in western China, likely increasing turbidity and decreasing ecosystem services such as fisheries.

© The Author(s) 2019. As part of the Changing the Face of the Mediterranean Project, we consider how human pressure and concomitant erosion has affected a range of Mediterranean landscapes between the Neolithic and, in some cases, the post-medieval period. Part of this assessment comprises an investigation of relationships among palaeodemographic data, evidence for vegetation change and some consideration of rapid climate change events. The erosion data include recent or hitherto unpublished work from the authors. Where possible, we consider summed probabilities of 14 C dates as well as the first published synthesis of all known optically stimulated luminescence dated sequences. The results suggest that while there were some periods when erosion took place contemporaneously across a number of regions, possibly induced by climate changes, more often than not, we see a complex and heterogeneous interplay of demographic and environmental changes that result in a mixed pattern of erosional activity across the Mediterranean. ispartof: HOLOCENE vol:29 issue:5 pages:864-885 ispartof: location:SPAIN status: published

Rivers convey mineral sediment and organic carbon through the landscape but also store a significant part in floodplains for varying amounts of time. Reliable quantification of this storage component is necessary to understand the cascades and land-ocean transfers of sediment and organic carbon. Here, we quantified the Holocene floodplain sediment and organic carbon storage for four medium-sized rivers in Belgium, located in the European loess and sand belts. The results indicate that floodplains store large amounts of mineral sediment and soil organic carbon with most of the storage at greater depths below the surface. The observed regional variability in floodplain storage shows to be controlled by catchment characteristics and anthropogenic impact. The river basins which have known long-term anthropogenic impact do not only store on average 4.4 times more sediment, but also 2.6 times more organic carbon. Even more, the historic human impact trajectory has a profound impact on the sensitivity of the organic carbon stock to external factors in current times. The observed variability in floodplain storage, both within and between river basins, shows to be large, even for river basins which have experienced similar environmental conditions, obscuring simple scale relations that would allow budgeting of global floodplain sediment and carbon stocks under anthropogenic impact.

The aim of this paper is to assess the impacts of projected climate change on a Mediterranean catchment, and to analyze the effects of a suite of representative land use practices as an adaptation tool to reduce climate change-driven erosion and hydrologic extremes. Relevant climatic variables from the ERA-Interim global atmospheric reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF) were downscaled for the study area, and perturbed with the anomalies of 23 global circulation models for three emission scenarios (B1, A1B and A2). Both a projected daily rainfall time series for the period 2010-2100, and a single precipitation event with a one-hundred year return period were used to assess the impact of climate change. The downscaled data were fed into a distributed hydro-sedimentary model (TETIS) with five land use configurations representative of future demographic tendencies, geographical characteristics and land management policies (e.g. European Union CAP). The projected changes showed a general decrease in runoff and sediment production by the end of the century regardless of land use configuration. Sediment production showed a positive relationship with an increase in agricultural land and a decrease in natural land under present day agricultural management. According to our simulations, some conservation practices in agriculture can effectively reduce net erosion while maintaining agricultural production. As such, they can play a critical role as an adaptation tool to reduce climate change impacts in the 21st century., This study was funded by the Spanish Ministry of Economy and Competitiveness through the research projects CLARIES (ref. CGL2011-29176) and PALEOMED (CGL2014-58127-C3-1-R).

The middle reaches of the Yellow River Basin transport the vast majority of sediment (>85% of the basin's total available sediment load), which has had profound effects on the characteristics of the middle and lower reaches of the Yellow River. With recent land use and land cover change, the Yellow River Basin has experienced significant sediment regime fluctuations. In this study, we analyzed the sediment regime from the Wuqi catchment which feeds into the upper reaches of the Beiluo River. Results show that a significant decreasing trend in annual suspended sediment discharge and suspended sediment concentration has existed from 1985 to 2008. The change-point year (the year that abrupt changes in sediment regime occurred in the catchment) was detected in 2001 (p

Deep erosional gullies dissect landscapes around the world. Existing erosion models focus on predicting where gullies might begin to erode, but identifying where existing gullies were initiated and under what conditions is difficult, especially when historical records are unavailable. Here we outline a new approach for fingerprinting alluvium and tracing it back to its source by combining bulk sediment optically stimulated luminescence (bulk OSL) and meteoric 10Be (10Bem) measurements made on gully-derived alluvium samples. In doing so, we identify where gully erosion was initiated and infer the conditions under which such erosion occurred. As both 10Bem and bulk OSL data have distinctive depth profiles in different uneroded and depositional settings, we are able to identify the likely incision depths in potential alluvium source areas. We demonstrate our technique at Birchams Creek in the southeastern Australian Tablelands—a well-studied and recent example of gully incision that exemplifies a regional landscape transition from unchanneled swampy meadow wetlands to gully incision and subsequent wetland burial by post-European settlement alluvium. We find that such historic alluvium was derived from a shallow erosion of valley fill upstream of former swampy meadows and was deposited down the center of the valley. Incision likely followed catchment deforestation and the introduction of livestock, which overgrazed and congregated in valley bottoms in the early 20th century during a period of drought. As a result, severe gully erosion was likely initiated in localized, compacted, and oversteepened reaches of the valley bottom.

Soil erosion and sediment delivery models have been developed to estimate the inherent complexities of soil erosion, but most models are not specifically modified for forest operation applications. Three erosion models, the Universal Soil Loss Equation for forestry (USLE-Forest), Revised Universal Soil Loss Equation Version 2 (RUSLE2), and Water Erosion Prediction Project (WEPP), were compared to one year of trapped sediment data for 37 forest haul road stream crossings. We assessed model performance from five variations of the three erosion models: USLE-Roadway, USLE-Soil Survey, RUSLE2, WEPP-Default, and WEPP-Modified. Each road approach was categorized into one of four levels of erosion (very low, low, moderate, and high) based on trapped erosion rate data and erosion rates reported in recent peerreviewed literature. Model performance metrics included: (1) summary statistics and nonparametric analysis, (2) linear relationships, (3) percent agreement within erosion categories and tolerable error ranges, and (4) contingency table metrics. Sediment trap data varied from negligible (

Severe environmental degradation in the north Ethiopian Highlands is among others the result of mismanagement, overpopulation and droughts. However, here, we investigate the linkages of land degradation with the historical dynamics of the political–ecological system and regional land policies. We performed semi-structured interviews with 93 farmers in eight villages in the Tigray region (north Ethiopia) and conceptualised a political–ecological model of land tenure and degradation changes for the region. Results show that different land policies caused and still cause land degradation in several ways. Interviews reveal that the unequal character of land rights during feudal times played an important role in 19th and 20th century land degradation. In particular, poor farmers were forced to construct their farms on marginal terrains, such as steep slopes in dry areas and marshes in cold and humid areas, increasing the catchment water runoff and degradation. The interviews further suggest that after the Derg regime (1974–1991), environmental conservation strategies were successfully implemented at larger scales. Overall, feudal, Derg and contemporary land policies have all had impacts on environmental degradation and have left their fingerprints on the physical landscape of northern Ethiopia. Copyright © 2014 John Wiley & Sons, Ltd.

The catchments in the western Rift Valley escarpment of northern Ethiopia are highly responsive in terms of hydro-geomorphic changes. With deforestation, dense gully and scar networks had developed by the 1980s on the escarpment between the towns of Alamata and Korem, transporting huge amounts of runoff and sediment down to the fertile and densely populated Raya Valley. To reverse this problem, catchment-scale rehabilitation activities were initiated in the mid-1980s. In this study, we examine the major hydro-geomorphic response of streams after catchment rehabilitation. Scar networks in 20 adjacent catchments were mapped on Google Earth imagery of 2005, and their density was explained in terms of its corresponding Normalized Difference Vegetation Index and slope gradient. Soil and water conservation measures and vegetation recovery have reduced discharge and sediment flow which in turn resulted in various hydro-geomorphic changes. In a multiple regression analysis, scar density was negatively related with Normalized Difference Vegetation Index and positively with average gradient of very steep slopes (r2 = 0·53, p

Developing models to predict on-site soil erosion and off-site sediment transport at the agricultural watershed scale represent an on-going challenge in research today. This study attempts to simulate the daily discharge and sediment loss using a distributed model that combines surface and sub-surface runoffs in a small hilly watershed (0.9. With the simple input data needs, PLER model is a useful tool for daily runoff and soil erosion modeling in small hilly watersheds in humid tropical areas.

The Chinese Loess Plateau is one of the most rapidly eroding regions in the world. The purpose of this study is to find out to which extent soil erosion on the Loess Plateau is driven by sunspot activity. We analyzed the relation between annual sediment discharge (from 1919 to 2010) from the Loess Plateau and the relative sunspot number, using Complex Morlet wavelets. We divided sediment discharge into 2 periods: before and after 1980 the year where the large-scale implementation of soil and water conservation techniques started. Before 1980, sediment discharge followed a 6 and 11-year period, the 11-year period being the most important one within a 25-year scale. After 1980, the impact of soil and water conservation techniques on the soil erosion in the Loess Plateau became obvious. The period of sediment discharge changed to, 4, 7 and 12-year periods, the 12-year period dominating the record. Similar analyses were conducted for the sunspot relative number, with an 11-year period dominating the record from 1919 to 2010. In different periods, the population, farm land area, land use/cover patterns and other factors have changed significantly. Although this has certainly affected sediment magnitudes, solar activity remains a clear (indirect) forcing factor for soil erosion in the Loess Plateau throughout the period of analysis. This underlines that solar activity influences Earth processes and argues for a more complete analysis of the pathways through which this happens.

In northern clay soils, field drainage is needed to ensure suitable moisture conditions for crop growth and farming operations. Supplementary drainage installations improve the efficiency of old drainage systems, but the hydrological impacts of the drainage procedures are not comprehensively understood or quantified. The objective was to simulate the hydrological behavior of a clay field section and to quantify the effects of a supplementary drainage on the water balance of the field section. The study site, in southern Finland, was originally subsurface drained in 1952 with 32 m drain spacing. Supplementary drainage was installed in 2014, decreasing the drain spacing to 10.7 m. Simulations were carried out with a dual-permeability hydrological model and two model parametrizations describing the field hydrology (1) before and (2) after the supplementary drainage installation. The parameterizations were used for simulations of a nine-year period to quantify the hydrological impacts of the supplementary drainage. For the periods without snow on the ground, the modified Nash-Sutcliffe efficiency for daily drain discharge and topsoil layer runoff values ranged from 0.43 to 0.53 and from 0.44 to 0.53, respectively. During the original drainage setup scenario, the average annual drain discharge was lower (7.8% of precipitation) than topsoil layer runoff and groundwater outflow (10.3% and 26.4%, respectively). For the supplementary drainage scenario, most of the water outflow was through drain discharge and groundwater outflow (20.4% and 21.9%, respectively). The supplementary drainage installation increased the average annual drain discharge by a factor of 2.6, while the annual average topsoil layer runoff and groundwater outflow decreased by 75% and 18%, respectively. The supplementary drainage setup was found to expedite the drying of the field section in spring by 8 days on average compared to the original drainage setup.

The sedimentation is a pervasive complex hydrological process subjected to each and every reservoir in world at different extent. Hydrographic surveys are considered as most accurate method to determine the total volume occupied by sediment and its distribution pattern in a reservoir. But, these surveys are very cumbersome, time consuming and expensive. This complex sedimentation process can also be simulated through the well calibrated numerical models. However, these models generally are data extensive and require large computational time. Generally, the availability of such data is very scarce. Due to large constraints of these methods and models, in the present study, data driven approaches such as artificial neural networks (ANN), model trees (MT) and genetic programming (GP) have been investigated for the estimation of volume of sediment deposition incorporating the parameters influenced it along with conventional multiple linear regression data driven model. The aforementioned data driven models for the estimation of reservoir sediment deposition were initially developed and applied on Gobindsagar Reservoir. In order to generalise the developed methodology, the developed data driven models were also validated for unseen data of Pong Reservoir. The study depicted that the highly nonlinear models ANN and GP captured the trend of sediment deposition better than piecewise linear MT model, even for smaller length datasets. (C) 2013 Elsevier B. V. All rights reserved.

Aim To characterize the changing fire regime of a Mediterranean landscape during the Holocene and the Last Interglacial and, by comparing the two periods, to improve our understanding of the extent and timing of human alteration of natural fire regimes. Location Lake Ioannina, north-western Greece (39°45′ N, 20°51′ E). Methods Using a long sequence of lake sediments, we measured the charcoal content of the sediment over the course of the Holocene and the Last Interglacial. We compared the charcoal data with pollen data for the same periods. Results Charcoal was present in all samples analysed. Charcoal influx was greater during interglacials, which at Ioannina were forested, than during glacials, when tree populations were small. Charcoal influx was greater and more variable during the Holocene than during the Last Interglacial. Main conclusions Fire was a persistent feature throughout the periods studied, under both glacial and interglacial conditions. Overall, more biomass was burned during interglacials than during glacials, and peak burning occurred at intermediate values of moisture availability. There is little evidence that the composition of forests significantly affected burning regimes. Enhanced burning during the Holocene relative to the Last Interglacial may reflect human impact, as well as climatic or vegetational differences between the two periods.

Wind-driven rain (WDR) experiments were conducted to evaluate the interrill component of the Water Erosion Prediction Project model with a two-dimensional experimental set-up in a wind tunnel. Synchronized wind and rain simulations were applied to soil surfaces on windward and leeward slopes of 7, 15 and 20%. Since WDR fall trajectory varied with horizontal wind velocities of 6, 10, and 14 m s−1, magnitude of raindrop normal and lateral stresses on flow at the impact-flow boundary also changed and differentially directed lateral jets of raindrop splashes with respect to downward flows occurred. To account for interactions between raindrop impact and interrill shallow flow, a vector approach with kinetic energy fluxes of both raindrop splashes and flow were used and this resulted in greater correlations in predicting sediment delivery rates.

The vector physics of wind-driven rain (WDR) differs from that of wind-free rain, and the interrill soil detachment equations in the Water Erosion Prediction Project (WEPP) model were not originally developed to deal with this phenomenon. This article provides an evaluation of the performance of the interrill component of the WEPP model for WDR events. The interrill delivery rates were measured in the wind tunnel facility of the International Center for Eremology (ICE), Ghent University, Belgium with an experimental setup to study different raindrop impact velocity vectors. Synchronized wind and rain simulations with wind velocities of 6, 10 and 14 m s–1 were applied to a test surface placed on windward and leeward slopes of 7, 15 and 20%. Since both rainfall intensity and raindrop impact velocity varied greatly depending on differences in the horizontal wind velocity under WDRs, the resultant kinetic energy flux (KEr, in J m–2 s–1) was initially used in place of the WEPP model intensity term in order to incorporate the effect of wind on impact velocity and frequency of raindrops. However, our results showed only minor improvement in the model predictions. For all research data, the model Coefficients of Determination (r2) were 0·63 and 0·71, when using the WEPP and the KEr approaches, respectively. Alternately, integrating the angle of rain incidence into the model by vectorally partitioning normal kinetic energy flux (KErn, in J m–2 s–1) from the KEr greatly improved the model's ability to estimate the interrill sediment delivery rates (r2¿=¿0·91). This finding suggested that along with the fall trajectory of wind-driven raindrops with a given frequency, raindrop velocity and direction at the point of impact onto the soil surface provided sufficient physical information to improve WEPP sediment delivery rate predictions under WDR

A reduced complexity model, which simulates the process of fluvial inland-delta formation, has been developed in a previous study. The results have been compared and validated with a laboratory experiment. This work elaborates the laboratory investigation in which an experimental inland delta is generated and its eroding topography is measured using a structured-light 3D scanner. The least squares 3D (LS3D) co-registration and comparison method is used for alignment as well as for comparing data epochs both spatially and temporally. A spatial precision value of around ±50 μm (1/20 000) is achieved. A series of high-quality digital elevation models (DEMs) are generated and the space-time evolution of the inland delta is monitored and analysed, in terms of slope and topography dynamics, in the consecutive DEM layers. The combination of high-resolution scanning together with high-precision co-registration techniques allows investigation of the details of the space-time variability of the sedimentation-deposition patterns to be used for geomorphological analysis. Resume Un modele de complexite reduite, qui simule le processus de formation d'un delta interieur, a ete developpe dans une precedente etude. Les resultats ont ete compares et valides dans le cadre d'une experience en laboratoire qui est decrite dans cet article. Un delta interieur experimental est forme, et sa topographie sujette a l'erosion est mesuree au moyen d'un scanner 3D a lumiere structuree. La methode LS3D de recalage et comparaison par moindres carres est utilisee pour l'orientation et pour comparer, dans l'espace et dans le temps, les donnees acquises a differentes dates. Une precision spatiale de l'ordre de ±50 μm (1/20 000) est obtenue. Une serie de modeles numeriques de terrain (MNT) de haute qualite est produite et l’evolution spatio-temporelle du delta interieur est surveillee et analysee, en termes de pente et de dynamique topographique, dans les MNT consecutifs. La combinaison du scanner a haute resolution avec les techniques de recalage de haute precision permet d’etudier en detail la variabilite spatio-temporelle des motifs de depot sedimentaire pour l'analyse geomorphologique. Zusammenfassung In einer vorangegangenen Studie wurde ein sogenanntes “reduced complexity” Computermodel zur Simulation von Inlanddeltas vorgestellt, und die Resultate mit Experimenten und Feldmessungen verglichen. Hier vertiefen wir die Analyse des Experiments, welches die Erosions- und Ablagerungsprocesse der Deltadynamik auf Laborscalen nachbildet. Die Anderung der Oberflachentopographie wurde mit Hilfe eines hochauflosenden “structured light” Scanner gemessen. Zur Kombination und Co-registrierung der einzelnen Oberflachenteilstucke kam der LS3D Algorithmus zum Einsatz, welcher es erlaubt Oberflachenmodelle mit einer Prazission von ±50 μm (1/20 000) zu verschiedenen Zeiten des Experiments zu erzeugen. Diese hochaufgelosten und co-registrierten Oberflachenmodelle konnen dazu verwendet werden Veranderungen in der Topographie in Raum und Zeit zu beschreiben, was dabei hilft die Dynamik der zu grunde liegenden geomorphischen Prozesse besser zu verstehen. Resumen En un estudio previo se ha desarrollado un modelo de complejidad reducida, que simula el proceso de formacion en el interior-delta fluvial. Los resultados se han comparado y validado con un experimento de laboratorio. Este trabajo explica con detalle el experimento de laboratorio en el que se genera un delta interior experimental y, usando un escaner 3D de luz estructurada, se mide la topografia erosionada. Se usa el co-registro 3D de minimos cuadrados y el metodo LS3D tanto para la alineacion como para comparar datos espacial y temporalmente. Se alcanza una precision espacial alrededor de ±50 micras (1/20 000). Se han generado una serie de modelos de elevacion digital de alta calidad (DEM) monitorizandose y analizandose, en terminos de dinamica de pendiente y topografia, la evolucion espacio-temporal del delta interior mediante las capas DEM consecutivas. La combinacion de escaneo de alta resolucion junto con tecnicas de co-registro de alta precision permite la investigacion de los detalles de la variabilidad espacio-temporal de patrones de sedimentacion y deposicion que se han utilizado para el analisis geomorfologico. 摘要 在前面的研究中,已采用降阶的复杂模型来模拟河流内陆三角洲形成过程,并与实验室实验的结果进行了比较和验证。本文阐述了实验室验证中,制作了试验性的内陆三角洲,其侵蚀地形采用结构光三维扫描仪进行测量。采用三维最小二乘配准方法用来进行不同时间空间的侵蚀状态的配准,空间精度达到±50 μm (1/20 000)。利用序列高质量的数字高程模型,从坡度和地形动态方便,对内陆三角洲的侵蚀过程进行了监测和分析。组合高分扫描和高精度配准技术可用来调查地貌分析中沉积模式的连续时空变化细节。

The frequency of individual plant species at ground level and the species composition of the unimproved vegetation on a western hill farm, stocked with Scottish Blackface sheep, were monitored from 1995 to 2008. Performance criteria of the flock that relied totally, or almost totally, on this vegetation for sustenance from 1994 to 2011 were evaluated. The frequency of vegetation increased over time (from 65% to 82% of the surface area;P< 0.05), with a corresponding decline in the frequency of bare soil, thus reducing vulnerability to soil erosion. This increased incidence of vegetation cover reflected increases in ‘other forbs’(P< 0.01), heather(P< 0.05)and grass (P< 0.08).A significant change (P< 0.05) also occurred in the species composition of the vegetation, reflecting an increase in the proportions of ‘other forbs’ (P< 0.05) and heather (P= 0.14), and a decline in the proportion of sedges (P= 0.14). A similar pattern occurred in the two main habitats: blanket bog and wet heath. Annual stocking rate (ewes per hectare, based on actual ewe grazing days) on the unimproved hill grazing averaged 0.9 (0.13 livestock units) per hectare prior to 1999 and 0.78 (0.11 livestock units) per hectare subsequently. There was no trend in weight gain of replacement females while confined to the unimproved hill area between weaning (14 weeks old) and first joining at 18 months of age. A negative trend (P< 0.01) occurred in the pre-weaning growth rate of lambs on the hill. The average number of lambs reared per ewe joined (reflecting fertility, litter size and ewe/lamb mortality) was 1.0, and this showed no evidence of change over time. The study flock performed 10% to > 60% better, depending on the variable, than similar flocks in the National Farm Survey at comparable stocking rates. A well-defined rational management system can sustain a productive sheep enterprise on unimproved hill land without negative consequences for the frequency or composition of the vegetation.

Landscape evolution models (LEMs) quantitatively simulate processes of sedimentation and erosion on millennial timescales. An important aspect of human impact on erosion is sediment redistribution due to agriculture, referred to herein as tillage erosion. In this study we aim to analyse the potential contribution of tillage erosion to landscape development using LEM LAPSUS. The model is calibrated separately for a water erosion process (i) without tillage and (ii) with tillage. The model is applied to the ~250¿km2 Torrealvilla case study catchment, SE Spain. We were able to simulate alternating sequences of incision and aggradation, that are important on longer (millennial) timescales. Generally, model results show that tillage erosion adds to deposition in the lower floodplain area, but neither water erosion alone nor water with tillage erosion together could exactly reproduce the observed amounts of erosion and sedimentation for the case study area. In addition, scale effects are apparent. On hillslopes, tillage may contribute importantly to erosion and may fill local depressions. If assessed on the catchment scale, sediments from tillage erosion eventually reach the lower floodplain area where they contribute to deposition. However, water erosion was observed in the model simulations to be the most important process on the catchment scale. This is the first time that tillage erosion has been explicitly included in a landscape evolution model at a millennial timescale and large catchment scale.

Lake Elton is located east of the Volga River in Russia and covers an area of 155¿km2. The hydrological system of the Lake and its surroundings are extremely vulnerable to climate change and human interference, but available local and regional information is sparse. Utilising climate data from 1987 to 2009 and surface albedo readings from the MODerate resolution Imaging Spectroradiometer satellite since 2000, this study analyses Lake degradation processes since 2005. Lake surface albedo analysis indicates that during the past 6¿years, lake albedo has increased dramatically from average peak values of 0·14 to 0·40. In addition, air temperature has increased by 2¿°C, and annual precipitation has decreased by 40 per cent. Moreover, human intervention in the area has increased environmental pressure on the Lake, causing a reduction of runoff inflow because of water capture, use of check-dams and water-harvesting systems. The results of the study show that, under current conditions, the Lake surface albedo is likely to remain high as compared with previous observations. The current trend implies an average 2 per cent per year increase in future annual albedo, with a maximum possible increase of 4 per cent up to a steady state of salt-crust albedo values

Changes in land use and production systems are to a large extent responsible for land degradation. In Portugal this process has been triggered mainly by socioeconomic drivers, such as agricultural technology, demography and policy changes. In this article land use changes in Portugal are discussed in terms of their main drivers and impacts, focussing on land degradation and conservation. The discussion includes a brief outline of historical land use changes in Portugal and a more detailed account of the changes in the period after 1986, when Portugal joined the European Union. An assessment of recent (1986–2006) land use changes and their impact was conducted for two selected research areas in the Centro and Alentejo regions. This assessment was based on information from the CORINE Land Cover programme (1985 and 2006) and the National Agricultural Census (1989 and 1999). In the Centro research area the land under forest declined from 52% to only 22% of the area, mainly as a result of forest fires. In the Alentejo research area the major change was the decline of miscellaneous shrub, declining from 23% to 11%, to open forest land, increasing as a result of afforestation measures from 1% to 22%. These land use changes resulted in a significant increase of soil loss estimates through RUSLE. In the Centro research area soil losses greater than 10 t ha−1 yr−1 were estimated to occur in 57% of the area in 1990, increasing as a result of land use change to 64% in 2006. In the Alentejo research area this change was from 65% in 1990 to 72% in 2006. The research raises questions regarding land use management, in relation to the Common Agriculture Policy support during the 1986–2006 period. Despite the increase in forest and permanent grassland areas, soil loss rates remain very high in the two research areas.

International audience; Controversy surrounds the promotion of conservation agriculture (CA) in smallholder farming systems in sub-Saharan Africa. The introduction of CA is a profound change in farm management. Benefits in reduced erosion and stabilized crop production may be obtained, but technical performance at field level is but one of the determinants of adoption. For various reasons, all of the CA principles are not always fully implemented by farmers and results not as favourable as expected. As with other approaches to increasing agricultural productivity, the production constraints, farmers' objectives, and the expected benefits and costs of implementing CA are important aspects that influence adoption. At farm and village levels, trade-offs in the allocation of resources become important in determining how CA may fit into a given farming system. At a regional level, factors such as the market conditions, interactions among stakeholders and other institutional and political dimensions become important. At each level, opportunities or difficulties emerge that enhance or impede development, adaptation and adoption of CA. The ex-ante identification of situations for where CA (and which form of CA) is appropriate demands research from a multi-stakeholder, multi-level, and interdisciplinary perspective. Recommendations are made where research is required to address key knowledge gaps.

This study compares three landscape evolution models and their ability to correctly simulate measured 2500¿year landscape evolution in two small catchments in the Belgian loess belt. WATEM LT and LAPSUS both model tillage and water erosion and deposition and have detachment-limited descriptions for water erosion and deposition. Equations in LAPSUS are more mechanistic than those in WATEM LT. WATEM LTT resembles WATEM LT, but is a transport-limited model. All three models are DEM-based. Calibration and validation simulations were performed forward in time on (1D) transects for four spatial resolutions, and backward in time for (2D) catchments at 20¿m resolution. For transects, model outputs were compared with discretized observations of transect shape. For catchments, outputs were compared with point observations of palaeo-altitude, averaged over landscape element classes. For transects, the three models performed well, resulting in model efficiency factors of 0.92 to 0.99 for calibration and 0.62 to 0.96 for validation. However, for catchments, simulations showed that the transport-limited WATEM LTT model could not realistically simulate long-term landscape evolution. Performance of WATEM LT and LAPSUS at catchment scale was similar to that on transects, although LAPSUS has problems with backward calculation. Tests demonstrate that a transport-limited approach cannot be used to model long-term landscape evolution in the Belgian loess belt, which is in agreement with theoretical and empirical understanding of soil erosion processes in this environment. The difference in performance between transport-limited and detachment-limited models is clear only when the models are evaluated in a 2D catchment. The lack of such distinction when models were applied in a 1D transect highlights the importance of evaluating landscape evolution models in a 2D setting so that effects of flow convergence/divergence can be accounted for. Copyright © 2011 John Wiley & Sons, Ltd

This study tests a rapid, user-friendly method for assessing changes in erosion risk, which yields information to aid policy development and decision-making for sustainable natural resources management. There is currently a lack of timely, up-to-date and current information to support policy development on sustainable natural resources management in Uganda. The study was carried out in the Ngenge watershed, a typical catchment in the Ugandan Highlands, characterised by deforestation in favour of subsistence agriculture without adequate soil and water conservation measures. The watershed is experiencing soil erosion, sedimentation and flooding problems which are threatening agricultural productivity and food security. Sustainable management of environmental resources is needed to ensure a livelihood for the rural population which is dependent on the land. Historical erosion risk was evaluated in three steps using multi-temporal satellite data. First, current erosion risk was assessed by combining slope and vegetation cover during periods of high intensity rainfall. The data used for the assessment was obtained from public (free) satellite images. Erosion risk was then linked to land use and finally to the change in vegetation cover over the years 1980–2000. The analysis of erosion risk using rainfall, slope and NDVI (Normalised Difference Vegetative Index) as a proxy for vegetation cover gives an indication of the current erosion risk in the area. The results of historical vegetation cover change analysis indicate an overall increase in areas under erosion risk in the study area from 1980 to 2000. This method of erosion risk mapping provides a quick and straightforward means for identifying priority areas for interventions for soil and water resource management. Considering that resources are limited, the interventions to be appropriate have to be focused mainly on areas affected by degradation.

Two studies carried out among Burunge small-scale farmers disclosed a striking difference in their relation to the area’s natural resources over a period of less than fifteen years. The paper outlines how the Burunge had come to develop essentially trustful attitudes to the world they inhabit. Dramatic changes in official land policies in the 1970s had not changed this by the early 1990s. However, this was also a time when a new mode of farming became dominant in the area, which caused Burunge farmers to move from a view of nature as a reliable provider to become concerned over increased drought, diminishing soil fertility and accelerated soil erosion. Rainfall records did not tally with the perceived increased severity of drought and therefore it is concluded that the Burunge did not relate drought only to meteorological events but also understand drought as a function of a diminishing resource base.

Purpose The Ethiopian highlands are a fragile environment characterized by steep slopes, intense rainfall, a sparse vegetation cover, and the occurrence of flash floods. Although important efforts have been made to mitigate the ongoing soil erosion and land degradation problems, the sediment dynamics at medium-sized catchment scale (100–10,000 km2) are not fully understood. Therefore, this study aims to provide a better understanding of sediment export processes and the importance of flash flood events in semi-arid tropical catchments. Materials and methods Measuring campaigns were conducted in ten sub-catchments of the Geba, a tributary of the Tekeze, representative of the northern Ethiopian highlands. During two to four rainy seasons, the rivers were sampled for their suspended sediment concentration (SSC) and runoff discharge. Results and discussion Variations in SSC and sediment grain size distribution indicate changes in sediment supply during the rainy season due to the depletion of readily available sediments and the development of a vegetation cover. Also, during flood events, changes in sediment supply are observed. Sediment yields (i.e., 497–6,543 t km−2 year−1) are higher than suggested by previous studies and correlate with rainfall depth. The majority of sediment export occurs during a few short but intense flash floods. No clear effect of implemented soil and water conservation measures could be detected in the sediment yields of the catchments. Conclusions Sediment export rates in the Ethiopian highlands are high, are characterized by important changes in sediment supply, and are mainly controlled by the occurrence and magnitude of flash flood events. Mitigation measures to reduce sediment yield at the catchment scale should therefore not only focus on the reduction of hillslope erosion rates but also on the magnitude of these floods. ispartof: Journal of Soils and Sediments vol:10 issue:4 pages:611-627 status: published

Olive plantation systems occur in a wide variety throughout the Mediterranean, especially in sloping and mountainous areas. Recent drivers of change, including the widespread introduction of mechanisation, increased use of (chemical) inputs and (drip)irrigation have considerably added to this diversity. The various systems have very different resource use patterns and environmental and social performances. This article attempts to grasp these differences and to link systems characteristics to options for natural resources management in the spirit of contemporary agricultural policies that seek to promote a more sustainable agriculture. Cluster analysis was employed to classify 28 olive plantation systems distinguished by regional typologies developed for six study areas: Tras-os-Montes (Portugal), Cordoba and Granada/Jaen (both in Spain), Haffouz (Tunisia), Basilicata/Salerno (Italy) and West-Crete (Greece). Six types of olive plantation systems resulted: (a) very extensive, (b) traditional extensive, (c) semi-intensive low input, (d) semi-intensive high input, (b) intensive and (e) organic. Natural resources management options to address soil erosion, low biodiversity, wildfire risk and excessive water use are explored for each of these systems. In the discussion, it becomes evident that an important quality for a typology lies in its capacity to differentiate likely future development pathways. If options are known, policy-makers can make choices as to what the desired pathway is and what instruments to design to facilitate it.