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- Geosciences, Vol. 10, Pages 32: Acknowledgement to Reviewers of Geosciences in 2019
- Geosciences, Vol. 10, Pages 31: An Alternative Empirical Model to Estimate Watershed Sediment Yield Based on Hydrology and Geomorphology of the Basin in Data-Scarce Rift Valley Lake Regions, Ethiopia
Physical-based soil erosion models are playing an important role in the assessment of soil erosion, transportation, and deposition in the watershed. Most of these models were developed for data-rich areas of the world and they need a measured data to calibrate and validate their results. To apply such physical-based models, the main factor hindering is the lack of measured sediment data. The amount of sediment in the fluvial systems is the result of hydro-geomorphological processes of a watershed and the nature of stream flows. Therefore, this study aims to develop an alternative empirical model that generates the observed sediment data based on the hydro-geomorphology and nature of stream flows for Ziway Lake basin in the rift Valley of Ethiopia. By applying Soil and water Assessment Tool (SWAT), the lake basin was divided in to two sub-basins (Maki and Katar) with 26 of the watersheds within Maki. The SWAT model was calibrated and validated for both stream and sediment flow by using SUFI-2 program and its performance was assessed by using model evaluation statistics. With calibrated sediment flow rates of 26 Maki sub basins, an empirical model was developed by using its respective drainage area, average sub-basins slope, surface runoff, soil erodibility factor, stream flow rate, and average rive slopes. The applicability of the newly developed alternative model was tested by using model evaluation statistics and validated inside of Katar sub-basin. It is recommended to test the developed model in other basins to incorporate with SWAT CUP program to calibrate and validate the sediment yield at data scared area.
- Geosciences, Vol. 10, Pages 30: Are Arid Regions Always that Appropriate for Waste Disposal? Examples of Complexity from Yucca Mountain, Nevada
The study of the hydrology of arid regions greatly expanded at the end of the 20th century as humans sought to reduce groundwater pollution from landfills, waste dumps and other forms of land disposal. Historically viewed as wastelands where little or no water percolated to the underlying water table, the discovery of large-scale contamination beneath arid disposal sites such as the Hanford nuclear complex in eastern Washington jumpstarted an industry in studying the hydrology of arid vadose zones and their transport behavior. These studies showed that, in spite of hyper aridity in many areas, precipitation often did infiltrate to deep water. The efforts at Yucca Mountain, Nevada to design a high-level nuclear repository stand out as one of the largest of such studies, and one that fundamentally changed our understanding of not only water flow in fractured rocks, but also of the range of our uncertainty of hydrologic processes in arid regions. In this review and commentary, we present some of the initial concepts of flow at Yucca Mountain, and the evolution in research to quantify the concepts. In light of continued stockpiling of high-level waste, and the renewed interest in opening Yucca Mountain for high-level waste, we then focus on the significant surprises and unanswered questions that remained after the end of the characterization and licensing period; questions that continue to demonstrate the challenges of a geologic repository and our uncertainty about critical processes for long-term, safe storage or disposal of some of our most toxic waste products.
- Geosciences, Vol. 10, Pages 29: Relation between the Friction Angle of Sand at Triaxial Compression and Triaxial Extension and Plane Strain Conditions
The strength of sand is usually characterized by the maximum value of the secant friction angle. The friction angle is a function of deformation mode, density, and stress level and is strongly correlated with dilatancy at failure. Most often, the friction angle is evaluated from results of conventional compression tests, and correlation between the friction angle of sand at triaxial compression and triaxial extension and plane strain conditions is a vital problem of soil mechanics. These correlations can be obtained from laboratory test results. The failure criteria for sand presented in literature also give the possibility of finding correlations between friction angles for different deformation modes. The general stress-dilatancy relationship obtained from the frictional state concept, with some additional assumptions, gives the possibility of finding theoretical relationships between the friction angle of sand at triaxial compression and triaxial extension and plane strain conditions. The theoretically obtained relationships presented in the paper are fully consistent with theoretical and experimental findings of soil mechanics.
- Geosciences, Vol. 10, Pages 28: Geostatistics and Structure from Motion Techniques for Coastal Pollution Assessment along the Policoro Coast (Southern Italy)
The coastal system, with its physical chemical and biological components, is the place where the lithosphere, atmosphere and hydrosphere intersect and interact, and in which human activity has a considerable impact on the balance of the whole ecosystem. The aim of this study is to assess the health of the coastal environment in a natural protected area in Policoro (Italy). Sand samples have been collected and analysed to detect the presence of environmental contaminants and pollutants (heavy metals). A photogrammetric survey was carried out using an unmanned aerial vehicle (UAV), and an updated orthophoto of the area was obtained using the Structure from Motion (SfM) processing technique. Geostatistical techniques have been used to assess the distribution of the contaminants in the study area.
- Soil Aggregate Stability of Forest Islands and Adjacent Ecosystems in West Africa
Soil Aggregate Stability of Forest Islands and Adjacent Ecosystems in West Africa Amelie Baomalgré Bougma, Korodjouma Ouattara, Halidou Compaore, Hassan Bismarck Nacro, Caleb Melenya, Samuel Ayodele Mesele, Vincent Logah, Azeez Jamiu Oladipupo, Elmar Veenendaal, and Jonathan Lloyd SOIL Discuss., https//doi.org/10.5194/soil-2019-87,2020 Manuscript under review for SOIL (discussion: open, 0 comments) To better understand the development of forest islands in west Africa, our study focused on soil aggregates stability of these patches across a precipitation transect. Soil samples were taken from 0 to 5 cm and 5 to 10 cm depths and aggregate fractions with diameters: > 500, 500–250 μm and 250–53 μm determined using the water sieving method. The results showed significant higher proportion of stable meso and macroaggregates in forest islands and natural savanna compared to agricultural soil.
- Identifying and quantifying geogenic organic carbon in soils – the case of graphite
Identifying and quantifying geogenic organic carbon in soils – the case of graphite Jeroen H. T. Zethof, Martin Leue, Cordula Vogel, Shane W. Stoner, and Karsten Kalbitz SOIL, 5, 383–398, https://doi.org/10.5194/soil-5-383-2019, 2019 A widely overlooked source of carbon (C) in the soil environment is organic C of geogenic origin, e.g. graphite. Appropriate methods are not available to quantify graphite and to differentiate it from other organic and inorganic C sources in soils. Therefore, we examined Fourier transform infrared spectroscopy, thermogravimetric analysis and the smart combustion method for their ability to identify and quantify graphitic C in soils. The smart combustion method showed the most promising results.
- The soil fertility and leaf nutrient status in enset gardens in different altitude zones of the Gamo highlands, Ethiopia and inferences for Xanthomonas wilt prevalence
The soil fertility and leaf nutrient status in enset gardens in different altitude zones of the Gamo highlands, Ethiopia and inferences for Xanthomonas wilt prevalence Sabura Shara, Rony Swennen, Jozef Deckers, Fantahun Weldesenbet, Laura Vercammen, Fassil Eshetu, Feleke Woldeyes, Guy Blomme, Roeland Merckx, and Karen Vancampenhout SOIL Discuss., https//doi.org/10.5194/soil-2019-78,2019 Manuscript under review for SOIL (discussion: open, 2 comments) Nicknamed the tree against hunger, Enset (Ensete ventricosum) is an important multipurpose crop for the farming systems of the densely populated Gamo highlands in Ethiopia. Its high productivity and tolerance to droughts are major assets. Nevertheless, Enset production is severely threatened by a wilting disease. This observational study aims to assess soil and leaf nutrients in enset gardens at different altitudes, so see if fertility management can be linked to disease prevalence.
- Evaluating the effects of soil erosion and productivity decline on soil carbon dynamics using a model-based approach
Evaluating the effects of soil erosion and productivity decline on soil carbon dynamics using a model-based approach Samuel Bouchoms, Zhengang Wang, Veerle Vanacker, and Kristof Van Oost SOIL, 5, 367–382, https://doi.org/10.5194/soil-5-367-2019, 2019 Soil erosion has detrimental effects on soil fertility which can reduce carbon inputs coming from crops to soils. Our study integrated this effect into a model linking soil organic carbon (SOC) dynamics to erosion and crop productivity. When compared to observations, the inclusion of productivity improved SOC loss predictions. Over centuries, ignoring crop productivity evolution in models could result in underestimating SOC loss and overestimating C exchanged with the atmosphere.
- Constructed Technosols are key to the sustainable development of urban green infrastructure
Constructed Technosols are key to the sustainable development of urban green infrastructure Maha Deeb, Peter M. Groffman, Manuel Blouin, Sara Perl Egendorf, Alan Vergnes, Viacheslav Vasenev, Donna L. Cao, Daniel Walsh, Tatiana Morin, and Geoffroy Séré SOIL Discuss., https//doi.org/10.5194/soil-2019-85,2019 Manuscript under review for SOIL (discussion: open, 0 comments) The goal of this study was to discuss current methods to create soils adapted for various green infrastructure designs (GI). Investigating these new soils for several design categories of GI will provide technical information for management and design agencies. Moreover, these studies can serve as pioneer experiments to prevent recurring errors and thus providing improved plant growth practices. Results show that these constructed soils have a high potential to provide multiple soil functions.