- Geosciences, Vol. 8, Pages 78: Examples of Application of GASAKe for Predicting the Occurrence of Rainfall-Induced Landslides in Southern Italy
GASAKe is an empirical-hydrological model aimed at forecasting the time of occurrence of landslides. Activations can be predicted of either single landslides or sets of slope movements of the same type in a homogeneous environment. The model requires a rainfall series and a set of dates of landslide activation as input data. Calibration is performed through genetic algorithms, and allows for determining a family of optimal kernels to weight antecedent rainfall properly. As output, the mobility function highlights critical conditions of slope stability. Based on suitable calibration and validation samples of activation dates, the model represents a useful tool to be integrated in early-warning systems for geo-hydrological risk mitigation purposes. In the present paper, examples of application to three rock slides in Calabria and to cases of soil slips in Campania are discussed. Calibration and validation are discussed, based on independent datasets. Obtained results are either excellent for two of the Calabrian rock slides or just promising for the remaining case studies. The best performances of the model take advantage of an accurate knowledge of the activation history of the landslides, and a proper hydrological characterization of the sites. For such cases, GASAKe could be usefully employed within early-warning systems for geo-hydrological risk mitigation and Civil Protection purposes. Finally, a new release of the model is presently under test: its innovative features are briefly presented.
- Geosciences, Vol. 8, Pages 77: Simulating the Influence of Buildings on Flood Inundation in Urban Areas
Two-dimensional hydraulic modeling is fundamental to simulate flood events in urban area. Key factors to reach optimal results are detailed information about domain geometry and utility of hydrodynamic models to integrate the full or simplified Saint Venant equations in complex geometry. However, in some cases, detailed topographic datasets that represent the domain geometry are not available, so approximations—such as diffusive wave equation—is introduced whilst representing urban area with an adjusted roughness coefficient. In the present paper, different methods to represent buildings and approximation of the Saint Venant equations are tested by performing experiments on a scale physical model of urban district in laboratory. Simplified methods are tested for simulation of a real flood event which occurred in 2013 in the city of Olbia, Italy. Results show that accuracy of simulating flow depth with a detailed geometry is comparable to the one achieved with an adjusted roughness coefficient.
- Geosciences, Vol. 8, Pages 76: A Risk-Based Approach to Shelter Resilience following Flood and Typhoon Damage in Rural Philippines
The Philippines is exposed to numerous typhoons every year, each of which poses a potential threat to livelihoods, shelter, and in some cases life. Flooding caused by such events leads to extensive damage to land and buildings, and the impact on rural communities can be severe. The global community is calling for action to address and achieve disaster risk reduction for communities and people exposed to such events. Achieving this requires an understanding of the nature of the risks that flooding and typhoons pose to these communities and their homes. This paper presents the findings from a field based case study assessment of three rural settlements in the Philippines, where typhoons and associated flooding in recent years has caused significant damage to houses and livelihoods, leading to the reconstruction of homes that more often than not reproduce similar structural vulnerabilities as were there before these hazards occurred. This work presents a methodology for risk assessment of such structures profiling the flood and wind hazards and measuring physical vulnerability and the experience of communities affected. The aim of the work is to demonstrate a method for identifying risks in these communities, and seeks to address the challenge faced by practitioners of assisting communities in rebuilding their homes in more resilient ways. The work set out here contributes to the discussion about how best to enable practitioners and communities to achieve the sought for risk reduction and especially highlights the role that geoscience and engineering can have in achieving this ambition.
- Geosciences, Vol. 8, Pages 75: Integrated Study of Lithofacies Identification—A Case Study in X Field, Sabah, Malaysia
Understanding subsurface geology is essential for oil and gas exploration. Seismic facies interpretation is very useful in investigating this concept. The interpretation of the depositional setting of the X Field is achieved by integrating the seismic facies characteristics on 3D seismic data and well log data. Both the seismic and well log data are widely used in hydrocarbon exploration to map the subsurface, as they complement each other. Well logs yield the vertical resolution of the subsurface geology at the drilled well, whereas seismic data reveal the lateral continuity. The objective of this paper is to demonstrate the integration of 3D seismic data and well log data for lithofacies identification. Interpretation and analysis of lithofacies is carried out through the integration of the characteristics of seismic reflections with well information (logs). Horizons are interpreted based on the variation in seismic reflections on the seismic section, which is caused by the change in geology within seismic sequences. Well logs give detailed information at the points where the wells were drilled. Interpolating between these points and extrapolating away from the points into undrilled areas can be helpful in providing a better geological knowledge of an area. The result of this integrated study depicts the lithofacies in the area. This integrated study will provide a better insight with higher degree of reliability to the facies distribution and depositional setting of the X Field. The geological and geophysical aspects of the field will be documented.
- Geosciences, Vol. 8, Pages 74: Diffraction Enhancement Through Pre-Image Processing: Applications to Field Data, Sarawak Basin, East Malaysia
The future exploration plans of the industry is to find a small-scale reservoir for possible economic hydrocarbon reserves. These reserves could be illuminated by the super-resolution of full seismic data, including fractured zones, pinch-outs, channel edges, small-scale faults, reflector unconformities, salt flanks, karst, caves and fluid fronts, which are generally known as small scattering objects. However, an imaging approach that includes the diffraction event individually and images it constitutes a new approach for the industry; it is known as diffraction imaging. This paper documents results of a seismic processing procedure conducted to enhance diffractions in Sarawak Basin, using datasets from the Malaysian Basin to which no diffraction processing has been applied. We observed that the diffraction amplitude achieves maximum value when the detector is positioned vertically above the end point of the reflector, but drops off with increasing offset-distance from the point. Furthermore, the rate of attenuation of the diffracted wave energy is greater than that of the normal reflected wave energy in the same medium. In addition, the results indicate that the near offset and far angle stack data provide better diffraction events. In the other hand far offset and near angle stack provides the poor diffraction response. These results were revealed by angle-stacking of near-, mid-, and far-offsets data (4.5, 22.5 and 31.5 degrees) that was conducted to study amplitude and phase change of the diffraction curve. The final imaged data provides better faults definition in the carbonate field data.
- Comment on Soil organic stocks are systematically overestimated by
misuse of the parameters bulk density and rock fragment content
(Poeplau et al., 2017, SOIL, 3, 61–66)
Comment on Soil organic stocks are systematically overestimated by misuse of the parameters bulk density and rock fragment content (Poeplau et al., 2017, SOIL, 3, 61–66) Eleanor U. Hobley, Brian Murphy, and Aaron Simmons SOIL Discuss., https//doi.org/10.5194/soil-2017-23,2018 Manuscript under review for SOIL (discussion: open, 1 comment) This research is evaluates equations to calculate soil organic carbon (SOC) stocks. Although various equations exist for SOC stock calculations, we recommend using the simplest equation with lowest associated errors. Adjusting SOC stock calculations for rock content is essential. Using the mass proportion of rocks to do so minimises error.
- Physical, chemical and mineralogical attributes of a representative group of soils
from the Eastern Amazon, Brazil
Physical, chemical and mineralogical attributes of a representative group of soils from the Eastern Amazon, Brazil Edna Santos de Souza, Antonio Rodrigues Fernandes, Anderson Martins de Souza Braz, Fábio Júnior de Oliveira, Luís Reynaldo Ferracciú Alleoni, and Milton César Costa Campos SOIL Discuss., https//doi.org/10.5194/soil-2018-3,2018 Manuscript under review for SOIL (discussion: open, 0 comments) The study refers to a survey of the attributes of the main soils classes of the state of Pará, Eastern Brazilian Amazon. These soils have a good potential for agricultural use under natural conditions. In the study we observed that the soils are predominantely kaolinitic, but have relatively low aluminum and organic matter contents, with huge textural variability. The results enable a better understanding of Eastern Amazonian soils, whose extention reaches more than 1.2 million km2.
- Saturated and unsaturated salt transport in peat from a constructed fen
Saturated and unsaturated salt transport in peat from a constructed fen Reuven B. Simhayov, Tobias K. D. Weber, and Jonathan S. Price SOIL, 4, 63-81, https://doi.org/10.5194/soil-4-63-2018, 2018 Lab experiments were performed to understand solute transport in peat from an experimental fen. Transport was analyzed under saturated and unsaturated conditions using NaCl (salt). We tested the applicability of a physical-based model which finds a wide consensus vs. alternative models. Evidence indicated that Cl transport can be explained using a simple transport model. Hence, use of the physical transport mechanism in peat should be evidence based and not automatically assumed.
- Local soil quality assessment of north-central Namibia: integrating farmers' and technical knowledge
Local soil quality assessment of north-central Namibia: integrating farmers' and technical knowledge Brice Prudat, Lena Bloemertz, and Nikolaus J. Kuhn SOIL, 4, 47-62, https://doi.org/10.5194/soil-4-47-2018, 2018 Soil degradation is a major threat for farmers of semi-arid north-central Namibia. Having tools to assess soil quality is important to evaluate soil conditions and helps targeting important issues. We developed a soil evaluation toolbox that integrates farmers' field experiences and technical knowledge. The combination of local soil descriptions, field soil texture evaluation and soil colour provides locally meaningful information that reveals soil quality improvement potentials.
- How serious a problem is subsoil compaction in the Netherlands? A survey based on probability sampling
How serious a problem is subsoil compaction in the Netherlands? A survey based on probability sampling Dick J. Brus and Jan J. H. van den Akker SOIL, 4, 37-45, https://doi.org/10.5194/soil-4-37-2018, 2018 Subsoil compaction is an important soil threat. It is caused by heavy machines used in agriculture. The aim of this study was to estimate how large the area with overcompacted subsoils is in the Netherlands. This was done by selecting locations randomly and determining the porosity and bulk density of the soil at these locations. It appeared that 43 % of the soils in the Netherlands is overcompacted, and so we conclude that subsoil compaction is indeed a serious problem in the Netherlands.