Using Geochemical Fingerprints for Assessing Sediment Source Apportionment in an Agricultural Catchment in Central Argentina

In the hilly semi-arid region of central Argentina, where the agricultural frontier expands at the expense of natural ecosystems, soil erosion is one of the most alarming environmental problems. Thus, obtaining knowledge about the dynamics of erosive processes and identifying erosion hotspots constitutes a primary scientific objective. This investigation is focused on estimating the apportionments of main sources of sediments, at the mouth of a small catchment called Durazno del Medio, located in the province of San Luis, Argentina. Elemental Analysis, measured by Energy Dispersive X-ray Fluorescence (EDXRF), was used to select potential geochemical fingerprints of sediment. The unmixing model MixSIAR was applied to approximate the contribution of each identified source in the sediment accumulation areas at the mouth of the catchment. Potential sediment sources were selected using two criteria: (i) a hierarchical approach to identify the main geomorphological units (GUs) and (ii) the main land uses (LU), recognized by examining satellite images and field recognitions. The selected geochemical tracers were able to distinguish sources located in the Crystalline basement hills with loess-patched (CBH) as the main sediment contributors.

Soil erosion estimation using Geographic Information System (GIS) and Revised Universal Soil Loss Equation (RUSLE) in the Siwalik Hills of Nawalparasi, Nepal

Soil erosion is one of the gravest environmental threats to the mountainous ecosystems of Nepal. Here, we combined a Geographic Information System (GIS) with the Revised Universal Soil Loss Equation (RUSLE) to estimate average annual soil loss, map erosion factors, compare soil erosion risks among different land use types, and identify erosion hotspots and recommend land use management in the Girwari river watershed of the Siwalik Hills. The annual soil loss was estimated using RUSLE factors: rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), cover crops (C), and conservation practices (P), and erosion factors maps were generated using GIS. Results indicate highest total erosion occurring in hill forests (13,374.3 t yr–1) and lowest total erosion occurring in grasslands (2.9 t yr–1). Hill forests showed high to very severe erosion due to steepness of hills, open forest types, and minimal use of conservation practices. Also, erosion hotspots (>15 t ha–1 yr–1) occurred in only 4.2% of the watershed, primarily in steep slopes. Overall, these results provide important guidelines to formulate management plans and informed decisions on soil conservation at local to regional levels. While the study is the first effort to assess soil erosion dynamics in the Girwari river watershed, potential for application in other basins largely exists.

COMPENSATION AND COASTAL PROTECTION

In this presentation, the authors examine the circumstances in which public bodies and professionals retained by them can be liable to pay monetary compensation for erosion damage. Coastal engineering, together with the analysis of coastal processes, play an important role in this legal landscape. Public bodies may come under a duty to implement defensive works; but equally they may be responsible for adverse impacts from them, such as end effects erosion. Coastal engineers may be engaged to provide critical protective works; but they may be liable where works are not designed or built to required standards or for stipulated purposes. Difficulties in assessing likely risk due to changes associated with climate change add an additional dimension with the increased risk of failure of protective works facing conditions which may not have previously been considered in the design criteria. Drawing from a decade of experience acting for litigants and property owners in erosion hotspots in New South Wales, the authors identify the key principles that apply in Australia and other common law jurisdiction and discuss how these rules can apply to scenarios where a disaster arises on any coastline. Some of the cases covered were included in the 2017 review by the United Nations entitled "The Status of Climate Change Litigation".

Modelling Hydrological Processes and Identifying Soil Erosion Sources in a Tropical Catchment of the Great Barrier Reef Using SWAT

Study region: North Johnstone catchment, located in the north east of Australia. The catchment has wet tropical climate conditions and is one of the major sediment contributors to the Great Barrier Reef. Study focus: The purpose of this paper was to identify soil erosion hotspots through simulating hydrological processes, soil erosion and sediment transport using the Soil and Water Assessment Tool (SWAT). In particular, we focused on predictive uncertainty in the model evaluations and presentations—a major knowledge gap for hydrology and soil erosion modelling in the context of Great Barrier Reef catchments. We carried out calibration and validation along with uncertainty analysis for streamflow and sediment at catchment and sub-catchment scales and investigated details of water balance components, the impact of slope steepness and spatio-temporal variations on soil erosion. The model performance in simulating actual evapotranspiration was compared with those of the Australian Landscape Water Balance (AWRA-L) model to increase our confidence in simulating water balance components. New hydrological insights for the region: The spatial locations of soil erosion hotspots were identified and their responses to different climatic conditions were quantified. Furthermore, a set of land use scenarios were designed to evaluate the effect of reforestation on sediment transport. We anticipate that protecting high steep slopes areas, which cover a relatively small proportion of the catchment (4–9%), can annually reduce 15–26% sediment loads to the Great Barrier Reef.

Soil erosion in Austria – National calculations using regional data delivering local results for the ÖPUL programme

<p>Empirical models, such as the Revised Universal Soil Loss Equation (RUSLE) are in use since the 1950s to estimate the mean annual soil loss for single agricultural fields or spatially-distributed for larger areas (municipalities, regions or states). A particular focus on the computation of the RUSLE lies in the calculation of the respective factors on which the equation is built on and represent the erosivity of rainfall events, the erodibility of soils, the topography and land management. However, the RUSLE is highly susceptible to large errors in the prediction of the erosion rates of single agricultural parcels, due to the high variability of these factors in large areas (e.g. on national scale).</p><p>In this study, we present a parcel-sharp erosion map for the entire territory of Austria. We discuss frequent error sources of the factor computations and their consequences for the representativeness of erosion maps at nation-scale. Based on our results we discuss furthermore regional erosion hotspots and evaluate nationally funded management practices for soil erosion reduction as they are defined in the Austrian programme for an environmentally responsible agriculture (ÖPUL).</p><p>Since our approach depicts a novelty for Austria, we further describe opportunities for analysis of our results and highlight potential sources of errors, as well as regional and legal discrepancies of the distribution of national funds for soil conservation.</p>

Variação da linha de costa no litoral cearense (1984-2018)

A erosão costeira ocorre em várias partes do mundo. Ela, por vezes, destrói equipamentos e casas próximas da linha de costa causando prejuízos econômicos. No Estado do Ceará existem trechos que estão retrogradando, exemplo clássico é da área próxima do Porto do Mucuripe (Fortaleza). Diante do exposto, o objetivo deste estudo foi analisar a evolução da linha de costa de todo o Estado do Ceará, dentro da escala temporal de 1984 a 2018. Para alcançar esse objetivo foram realizados o processamento digital de imagens de satélite, confecção de mapas de variação da linha de costa e quantificação das áreas de progradação e retrogradação. Em termos matemáticos, na zona costeira do Ceará houve equilíbrio dinâmico entre os processos de acreção e erosão, contudo, existem alguns hotspots de erosão nos diferentes setores do litoral. Há a necessidade de monitoramento contínuo da zona costeira em diferentes escalas espaciais e temporais para melhor compreensão do comportamento costeiro, bem como políticas que inibam a ocupação deletéria a essa região. Shoreline variation in Ceará coastal zone (1984-2018) A B S T R A C TCoastal erosion occurs in several parts of the world. Sometimes, it destroys structures close to the shoreline causing economic damage. In the state of Ceará, Brazil, there are stretches with retrogradation. A classic example is from the area near the Mucuripe harbor (Fortaleza). From this context, the objective of this paper was to analyze the evolution of the State of Ceará shoreline between 1984 and 2018. To achieve this objective, the digital processing of satellite images was performed, developing maps of shoreline variation and quantification of progradation and retrogradation areas. In mathematical terms, at the coastal zone of Ceará there was a dynamic balance between the processes of accretion and erosion. However, there are some erosion hotspots in different sectors of the state shoreline. There is a need for continuous monitoring of the coastal zone in different spatial and temporal scales to better understand coastal behavior, as well as policies that inhibit the deleterious occupation of this region.Keywords: Coastal zone; Monitoring; Coastal Erosion.

Critical beaches due to coastal erosion in the Caribbean south of Costa Rica, during the period 2005-2016

Since 2010, the local press has been reporting an accelerated process of erosion on the sandy beaches of the Costa Rican Caribbean coast, it has even been documented within protected areas. To quantify this process and identify coastal erosion hotspots in the Caribbean south, a methodology was proposed for detecting and delineating the shoreline using aerial photographs and high-resolution satellite imagery to determine the rate of shoreline retreat, the employed photographs and images cover the period between 2005 and 2016. By such means it was possible to identify eleven erosion hotspots, as well as estimation of their retreat rates for the periods 2005-2010 and 2010-2016. The localities that have experienced the greatest erosion of their sandy beaches are Cahuita National Park, Westfalia and Bananito Beach.