Fire is a natural factor of landscape evolution in Mediterranean ecosystems. The middle Ebro Valley has extreme aridity, which results in a low plant cover and high soil erodibility, especially on gypseous substrates. The aim of this research is to analyze the effects of moderate heating on physical and chemical soil properties, mineralogical composition and susceptibility to splash erosion. Topsoil samples (15 cm depth) were taken in the Remolinos mountain slopes (Ebro Valley, NE Spain) from two soil types: Leptic Gypsisol (LP) in a convex slope and Haplic Gypsisol (GY) in a concave slope. To assess the heating effects on the mineralogy we burned the soils at 105 and 205 °C in an oven and to assess the splash effects we used a rainfall simulator under laboratory conditions using undisturbed topsoil subsamples (0–5 cm depth of Ah horizon). LP soil has lower soil organic matter (SOM) and soil aggregate stability (SAS) and higher gypsum content than GY soil. Gypsum and dolomite are the main minerals (>80%) in the LP soil, while gypsum, dolomite, calcite and quartz have similar proportions in GY soil. Clay minerals (kaolinite and illite) are scarce in both soils. Heating at 105 °C has no effect on soil mineralogy. However, heating to 205 °C transforms gypsum to bassanite, increases significantly the soil salinity (EC) in both soil units (LP and GY) and decreases pH only in GY soil. Despite differences in the content of organic matter and structural stability, both soils show no significant differences (P < 0.01) in the splash erosion rates. The size of pores is reduced by heating, as derived from variations in soil water retention capacity.
Solid Earth (SE) is an international scientific journal dedicated to the publication and discussion of multidisciplinary research on the composition, structure and dynamics of the Earth from the surface to the deep interior at all spatial and temporal scales. More at Solid Earth homepage.
Democritus University of Thrace, Xanthi, Greece
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Successful prediction of pathways of storm runoff generation and associated soil erosion is of considerable societal importance, including off-site impacts such as water quality and the provision of related ecosystem services. Recently, the role of connectivity in controlling runoff and erosion has received significant and increasing scientific attention, though in a disparate and uncoordinated way. There is a wealth of experience and expertise in connectivity across Europe that can move forward research along agreed lines and identify emerging goals, and to benefit from cross-fertilization of ideas from the fields of Hydrology, Soil Science, Geomorphology and Ecology.
The key benefit of this COST Action (ES1306) will therefore be to establish connectivity as a research paradigm. The Action will then permit transfer of current understanding into useable science, by developing its conceptual basis and transferring it into a series of monitoring and modelling tools that will provide the platform for indices that will inform holistic management of catchment systems.
The first scientific meeting of the CONNECTEUR group was held in Wageningen in August 2014 (24-25-26th). In this kickoff meeting we focused on setting the agenda for the coming 4 years in which the Action will run. Apart from several keynotes addressed to introduce the different working group aims, objectives and actions, there were people from outside of science that gave their view on the connectivity concept and shared with us the way this topic is viewed and approached by policy makers and end users. In this way we tried to link science and end-users communities to find common language and create an interactive atmosphere. In addition, we got to know each other, and each other’s work. Which is of course essential for collaboration. In the program there will be ample time to look at each other’s posters and discuss possible linkages and set up new synergies. In addition we discussed in breakout groups the view on the connectivity topic in different parts of Europe and finally the way we should move forward with this science in the different working groups.
If you are interested in the outcomes of the Action and in specific the outcomes of the meeting in Wageningen check out the CONNECTEUR website.
Surface runoff generation on arable fields is an important driver of flooding, on-site and off-site damages by erosion, and of nutrient and agrochemical transport. In general, three different processes generate surface runoff (Hortonian runoff, saturation excess runoff, and return of subsurface flow). Despite the developments in our understanding of these processes it remains difficult to predict which processes govern runoff generation during the course of an event or throughout the year, when soil and vegetation on arable land are passing many states. We analysed the results from 317 rainfall simulations on 209 soils from different landscapes with a resolution of 14 286 runoff measurements to determine temporal and spatial differences in variables governing surface runoff, and to derive and test a statistical model of surface runoff generation independent from an a priori selection of modelled process types. Measured runoff was related to 20 time-invariant soil properties, three variable soil properties, four rain properties, three land use properties and many derived variables describing interactions and curvilinear behaviour. In an iterative multiple regression procedure, six of these properties/variables best described initial abstraction and the hydrograph. To estimate initial abstraction, the percentages of stone cover above 10% and of sand content in the bulk soil were needed, while the hydrograph could be predicted best from rain depth exceeding initial abstraction, rainfall intensity, soil organic carbon content, and time since last tillage. Combining the multiple regressions to estimate initial abstraction and surface runoff allowed modelling of event-specific hydrographs without an a priori assumption of the underlying process. The statistical model described the measured data well and performed equally well during validation. In both cases, the model explained 71 and 58% of variability in accumulated runoff volume and instantaneous runoff rate (RSME: 5.2 mm and 0.23 mm min−1, respectively), while RMSE of runoff volume predicted by the curve number model was 50% higher (7.7 mm). Stone cover, if it exceeded 10%, was most important for the initial abstraction, while time since tillage was most important for the hydrograph. Time since tillage is not taken into account either in typical lumped hydrological models (e.g. SCS curve number approach) or in more mechanistic models using Horton, Green and Ampt, or Philip type approaches to address infiltration although tillage affects many physical and biological soil properties that subsequently and gradually change again. This finding should foster a discussion regarding our ability to predict surface runoff from arable land, which seemed to be dominated by agricultural operations that introduce man-made seasonality in soil hydraulic properties.
Hydrology and Earth System Sciences (HESS) is an international two-stage open access journal for the publication of original research in hydrology, placed within a holistic Earth System Science context. The discussion and peer-review of submitted papers are handled in the open access discussion journal HESSD. Final papers, upon acceptance, appear in HESS (see Review Process under the heading Review).
HESS encourages and supports fundamental and applied research that seeks to understand the interactions between water, earth, ecosystems and man. A multi-disciplinary approach is encouraged that enables a broadening of the hydrologic perspective and the advancement of hydrologic science through the integration with other cognate sciences, and the cross-fertilization across disciplinary boundaries. HESS, therefore, has the ambition to serve not only the community of hydrologists, but all earth and life scientists, water engineers and water managers, who wish to publish original findings on the interactions between hydrological processes and other physical, chemical, biological and societal processes within the earth system, and the utilization of this holistic understanding towards sustainable management of water resources, water quality and water-related natural hazards.
The scope of HESS therefore encompasses:
The role of physical, chemical and biological processes in the cycling of continental water in all its phases, including dissolved and particulate matter, at all scales, from the micro-scale processes of soil water to the global-scale processes underpinning hydro-climatology.
The study of the spatial and temporal characteristics of the global water resources (solid, liquid and vapour) and related budgets, in all compartments of the Earth System (atmosphere, oceans, estuaries, rivers, lakes and land masses), including water stocks, residence times, interfacial fluxes, and the pathways between various compartments.
The study of the interactions with human activity of all the processes, budgets, fluxes and pathways as outlined above, and the options for influencing them in a sustainable manner, particularly in relation to floods, droughts, desertification, land degradation, eutrophication, and other aspects of global change.
The journal will publish research articles, research and technical notes, opinion papers, book reviews, brief communications, and comments on papers published previously in HESS. Papers can address different techniques and approaches, including: theory, modelling, experiments or instrumentation. The journal covers the following Subject Areas and Techniques/Approaches, which are used to categorise papers:
This is one of the pictures the year has left. In it, two Muslim militiamen armed with machetes are registering a Christian in the Miskine neighborhood, in Bangui (Central African Republic), December 13, 2013. About 1,600 and 3,000 French soldiers already there of the African MISCA international mission were not able to stop violence and chaos.
Both in this case and in other armed conflicts, there are political motivations, ultimately rooted in inequality and poverty.
The maps below are a series edited by GRID Arendal that, at least, invite us to think. It’s the first thing I show my students every year when I start my course on Soil Science at the university and I encourage them to discuss their reasons and responsibility as soil scientists. I also invite you to take a look. Original sources include detailed descriptions, images and PDFs.
Is poverty in West Africa related with soil quality?
Finally, some statistics. These graphs do not show clear trends, probably because land degradation indicators need much more detail and spatial resolution than currently.
The aim of this study is to assess and to validate the suitability of the stable nitrogen and carbon isotope signature as soil erosion indicators in a mountain forest site in South Korea. Our approach is based on the comparison of the isotope signature of “stable” landscape positions (reference sites), which are neither affected by erosion nor deposition, with eroding sites. For undisturbed soils we expect that the enrichment of δ15N and δ13C with soil depth, due to fractionation during decomposition, goes in parallel with a decrease in nitrogen and carbon content. Soil erosion processes potentially weaken this correlation. The 137Cs method and the Revised Universal Soil Loss Equation (RUSLE) were applied for the soil erosion quantification. Erosion rates obtained with the137Cs method range from 0.9 t ha−1 yr−1 to 7 t ha−1 yr−1. Considering the steep slopes of up to 40° and the erosive monsoon events (R factor of 6600 MJ mm ha−1 h−1 yr –1), the rates are plausible and within the magnitude of the RUSLE-modeled soil erosion rates, varying from 0.02 t ha−1 yr−1 to 5.1 t ha−1 yr−1. The soil profiles of the reference sites showed significant (p < 0.0001) correlations between nitrogen and carbon content and its corresponding δ15N and δ13C signatures. In contrast, for the eroding sites this relationship was weaker and for the carbon not significant. These results confirm the usefulness of the stable carbon isotope signature as a qualitative indicator for soil disturbance. We could show further that the δ15N isotope signature can be used similarly for uncultivated sites. We thus propose that the stable δ15N and δ13C signature of soil profiles could serve as additional indicators confirming the accurate choice of the reference site in soil erosion studies using the 137Cs method.
Biogeosciences (BG) is an international scientific journal dedicated to the publication and discussion of research articles, short communications and review papers on all aspects of the interactions between the biological, chemical and physical processes in terrestrial or extraterrestrial life with the geosphere, hydrosphere and atmosphere. The objective of the journal is to cut across the boundaries of established sciences and achieve an interdisciplinary view of these interactions. Experimental, conceptual and modelling approaches are welcome. More at Biogeosciences homepage.