Past and future perspectives upon landscape instability in Cumbria, northwest England

Geomorphic and lacustrine evidence is used to identify phases of landscape instability in Cumbria, northwest England, British Isles. The temporal and spatial pattern of erosion is used alongside palaeovegetation data from across the region to elucidate the causes of landscape instability in the late Holocene. The lines of evidence include changes in sediment accumulation rate and provenance within the region’s lakes; the hillslope alluvial fan and gully incision record; the lowland fluvial geomorphic record; and pollen analytical data for the late Holocene vegetation history. The sediment supply driven hillslope and lacustrine records suggest that only the 1,200–800 BP and post 600–500 BP erosion episodes were both catchment-wide and directly affected upland hillslopes, with the earlier phases after 5,200 and 3,000–1,600 BP on a lower scale and more restricted spatially. These episodes coincide with major expansions or changes in anthropogenic activity during Neolithic, Iron Age and Romano-British, Norse and late Medieval times. The projected future trajectories of changes in both climate (UKCIP scenarios) and landuse (CAP reform and ESA status) appear unlikely to increase landscape instability, although a shift to greater incidence of storms and high magnitude flood events clearly could. The past shows that the largest increases in erosion and sediment movement occur in the wake of major intensifications in land pressure that primarily affect previously wooded or protected hillslopes, circumstances that land management strategists should mitigate against.     

Sediment budgets and source determinations using fallout Cesium-137 in a semiarid rangeland watershed,Arizona, USA

Analysis of soil redistribution and sediment sources in semiarid and arid watersheds provides information for implementing management practices to improve rangeland conditions and reduce sediment loads to streams. The purpose of this research was to develop sediment budgets and identify potential sediment sources using ¹³⁷Cs and other soil properties in a series of small semiarid subwatersheds on the USDA ARS Walnut Gulch Experimental Watershed near Tombstone, Arizona, USA. Soils were sampled in a grid pattern on two small subwatersheds and along transects associated with soils and geomorphology on six larger subwatersheds. Soil samples were analyzed for ¹³⁷Cs and selected physical and chemical properties (i.e., bulk density, rocks, particle size, soil organic carbon). Suspended sediment samples collected at measuring flume sites on the Walnut Gulch Experimental Watershed were also analyzed for these properties. Soil redistribution measured using ¹³⁷Cs inventories for a small shrub-dominated subwatershed and a small grass-dominated subwatershed found eroding areas in these subwatersheds were losing −5.6 and −3.2 t ha⁻¹ yr⁻¹, respectively; however, a sediment budget for each of these subwatersheds, including depositional areas, found net soil loss to be −4.3 t ha⁻¹ yr⁻¹ from the shrub-dominated subwatershed and −0.1 t ha⁻¹ yr⁻¹ from the grass-dominated subwatershed. Generally, the suspended sediment collected at the flumes of the six other subwatersheds was enriched in silt and clay. Using a mixing model to determine sediment source indicated that shrub-dominated subwatersheds were contributing most of the suspended sediment that was measured at the outlet flume of the Walnut Gulch Experimental Watershed. The two methodologies (sediment budgets and sediment source analyses) indicate that shrub-dominated systems provide more suspended sediment to the stream systems. The sediment budget studies also suggest that sediment yields measured at the outlet of a watershed may be a poor indicator of actual soil redistribution rates within these semiarid watersheds. Management of these semiarid rangelands must consider techniques that will protect grass-dominated areas from shrub invasion to improve rangeland conditions.     

Challenges of soil erosion and sludge management for sustainable development in Indonesia

Most developing countries, particularly Indonesia, will be facing problems of sludge pressure in the next decades due to the increase in practices of legal and illegal logging as well as land and water demands. Consequently, they will also be facing the challenges of soil erosion and sludge management due to increased quantities of sludge coming from several potential sources, such as activated sludge, chemical sludge, fecal sludge and solid wastes as well as erosion and sedimentation. Although the government of Indonesia has enacted laws and policies to speed up the implementation of the programs and activities related to sludge management, the detailed practice concepts in implementing the programs need to be identified. Discussion of role-sharing amongst the related government agencies, private institutions and other stakeholders is urgent for clarifying the participation of each party in the next years to come. This paper proposes a management approach and level of responsibilities in sludge management. Implementation of zero ΔQ, zero ΔS and zero ΔP policies needs to be adopted by local and central governments. Application of sludge on the agricultural lands and other uses will promote sustainable development.     

Establishment of control site baseline data for erosion studies using radionuclides: a case study in East Slovenia

The aim of the present study was to establish a reference site and its soil characteristics for use of fallout radionuclides in erosion studies in Slovenia. Prior to this study, no reference site and baseline data existed for Slovenia for this purpose. In the agricultural area of Gori?ko in East Slovenia, an undisturbed forest situated in Šalamenci (46°44’N, 16°7’E), was selected to establish the inventory value of fallout ¹³⁷Cs and to establish a baseline level of multi-elemental fingerprint (major, minor, trace elements including heavy metals) and naturally occurring radionuclides in soils. A total of 20 soil profiles were collected at four 10 cm depth increments for evaluation of baseline level of ¹³⁷Cs inventory. An exponential distribution for ¹³⁷Cs was found and the baseline level inventory was established at 7300 ± 2500 Bq m⁻² with a coefficient of variation of 34%. Of this mean present-day inventory, approximately 45% is due to the Chernobyl contribution.The physical degradation of soils through erosion is linked with biochemical degradation. This study introduces an approach to establishment of the naturally occurring radionuclide and elemental fingerprints baseline levels at a reference site which can provide comparative data to those from neighbouring agricultural fields for assessment of soil redistribution magnitude using fallout radionuclides. In addition, this information will be used to determine the impact of soil erosion processes and agricultural practices on soil quality and redistribution within agricultural landscapes in Slovenia.     

Assessment of Mangrove Response to Projected Relative Sea-Level Rise And Recent Historical Reconstruction of Shoreline Position

We predict the decadal change in position of three American Samoa mangroves from analysis of a time series of remotely sensed imagery, a geographic information system, tide gauge data, and projections for change in sea-level relative to the mangrove surface. Accurate predictions of changes to coastal ecosystem boundaries, including in response to projected relative sea-level rise, enable advanced planning to minimize and offset anticipated losses and minimize social disruption and cost of reducing threats to coastal development and human safety. The observed mean landward migration of three mangroves' seaward margins over four decades was 25, 64, and 72mma⁻¹, 12 to 37 times the observed relative sea-level rise rate. Two of the sites had clear trends in reductions in mangrove area, where there was a highly significant correlation between the change in position of the seaward mangrove margin and change in relative sea-level. Here it can be inferred that the force of sea-level rise relative to the mangrove surface is causing landward migration. Shoreline movement was variable at a third site and not significantly correlated with changing sea-level, where it is likely that forces other than change in relative sea-level are predominant. Currently, 16.5%, 23.4%, and 68.0% of the three mangroves' landward margins are obstructed by coastal development from natural landward migration. The three mangroves could experience as high as a 50.0% reduction in area by the year 2100. A 12% reduction in mangrove area by the year 2100 is possible in the Pacific islands region.     

Estimates of soil erosion using cesium-137 tracer models

The soil erosion was studied by ¹³⁷Cs technique in Yatagan basin in Western Turkey, where there exist intensive agricultural activities. This region is subject to serious soil loss problems and yet there is not any erosion data towards soil management and control guidelines. During the soil survey studies, the soil profiles were examined carefully to select the reference points. The soil samples were collected from the slope facets in three different study areas (Kırtas, Peynirli and Kayısalan Hills). Three different models were applied for erosion rate calculations in undisturbed and cultivated sites. The profile distribution model (PDM) was used for undisturbed soils, while proportional model (PM) and simplified mass balance model (SMBM) were used for cultivated soils. The mean annual erosion rates found using PDM in undisturbed soils were 15 t ha⁻¹ year⁻¹ at the Peynirli Hill and 27 t ha⁻¹ year⁻¹ at the Kırtas Hill. With the PM and SMBM in cultivated soils at Kayışalan, the mean annual erosion rates were obtained to be 65 and 116 t ha⁻¹ year⁻¹, respectively. The results of ¹³⁷Cs technique were compared with the results of the Universal Soil Loss Equation (USLE).     

Degrading permafrost river catchments and their impact on Arctic Ocean nearshore processes

Arctic warming is causing ancient perennially frozen ground (permafrost) to thaw, resulting in ground collapse, and reshaping of landscapes. This threatens Arctic peoples'' infrastructure, cultural sites, and land-based natural resources. Terrestrial permafrost thaw and ongoing intensification of hydrological cycles also enhance the amount and alter the type of organic carbon (OC) delivered from land to Arctic nearshore environments. These changes may affect coastal processes, food web dynamics and marine resources on which many traditional ways of life rely. Here, we examine how future projected increases in runoff and permafrost thaw from two permafrost-dominated Siberian watersheds—the Kolyma and Lena, may alter carbon turnover rates and OC distributions through river networks. We demonstrate that the unique composition of terrestrial permafrost-derived OC can cause significant increases to aquatic carbon degradation rates (20 to 60% faster rates with 1% permafrost OC). We compile results on aquatic OC degradation and examine how strengthening Arctic hydrological cycles may increase the connectivity between terrestrial landscapes and receiving nearshore ecosystems, with potential ramifications for coastal carbon budgets and ecosystem structure. To address the future challenges Arctic coastal communities will face, we argue that it will become essential to consider how nearshore ecosystems will respond to changing coastal inputs and identify how these may affect the resiliency and availability of essential food resources.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01666-z.     

Causes and consequences of salt-marsh erosion in an Atlantic estuary in SW Spain

This study reports on the quantification of horizontal erosion by undermining of slopes in the atlantic mesotidal salt marshes of Odiel, SW Spain, and analyses its causes and consequences. Horizontal erosion has produced considerable losses of salt marsh area, including zones of mature salt marsh. Human pressure, such as from water-borne traffic or the exploitation of the slopes for the capture of bait, increases the natural erosion processes. The role of vegetation in protecting the slopes against erosion is studied. Channel banks covered with plants, many of which belong to species with long-living, above-ground creeping stems, were less eroded than those without vegetation cover. The enormous volume of sediments moved (ca. 7000m³ in one year) could contribute to the silting-up of the navigable channels of the estuary, so that continual dredging is necessary to allow access to shipping. These sediments are highly contaminated, and dredging exposes them more directly to the trophic network of the estuary. There is a considerable loss of natural resources. Finally, the integrated management of this coastal ecosystem is discussed.     

Developing a National Indicator of Soil Quality on U.S Forestlands: Methods and Initial Results

The Montreal Process was formed in 1994 to develop an internationally agreed upon set of criteria and indicators for the conservation and sustainable management of temperate and boreal forests. In response to this initiative, the Forest Inventory and Analysis (FIA) and Forest Health Monitoring (FHM) programs of the United States Department of Agriculture Forest Service have implemented soil measurements as part of a national monitoring program to address specific questions related to the conservation of soil and water resources. Integration of soil assessments into the national FIA program provides for systematic monitoring of soil properties across all forested regions of the U.S. using standardized collection, laboratory, and statistical procedures that are compatible with existing forest inventory data. The resulting information will provide quantitative benchmarks for regional, national, and international reporting on sustainable forest management and enhance our understanding of management effects on soil quality. This paper presents an overview of the FIA soil monitoring program, outlines the field and laboratory protocols as currently implemented, and provides examples of how these data may be used to assess indicators of sustainable management as defined by the Montreal Process.     

邛海流域不同环境因素与土壤侵蚀相互关系研究

"基于USLE模型和多因素方差分析方法,以邛海流域为研究对象,研究不同海拔、坡度和土地利用类型下,土壤侵蚀强度的特征和规律。结果表明:不同海拔梯度下,随着海拔的升高,土壤侵蚀量呈先增后减再增的趋势。1 500~17 00 m海拔段是土壤侵蚀防治的重点区域。坡度对土壤侵蚀量的影响无明显的规律,但对土壤侵蚀量的产生有显著影响。15~25°坡度带是土壤侵蚀的重点预防和治理区域。不同的土地利用类型下,土壤侵蚀存在明显的差异。流域需加强旱地、园地和林地的治理。