- Geosciences, Vol. 9, Pages 484: Application of SAR Interferometry Using ALOS-2 PALSAR-2 Data as Precise Method to Identify Degraded Peatland Areas Related to Forest Fire
Deforestation in peatland areas such as Kalimantan, Indonesia has been going on for decades. The deforestation has indirectly increased peatlands to become degraded and flammable. The Synthetic Aperture Radar (SAR) interferometry approach for identification of degraded peatlands can be performed using ALOS-2 PALSAR-2 data by converting land deformation data generated from SAR interferometry analysis into water table (WT) depth data using Wosten models. Peatlands with WT depth conditions of more than 40 cm are classified as degraded peatlands which are flammable. By using fire data from previous studies, this research confirms that identification of degraded peatlands using SAR interferometry approach by ALOS-2 PALSAR-2 is more reliable with high precision related to forest fires, with a precision level of 88% compared to 5% precision level using the WT depth monitoring system that has been installed in Central Kalimantan. The highest wavelength of ALOS-2 PALSAR-2 (L-Band) data can resolve the limitation due to temporal and volumetric decorrelation, compared to C-Band and X-Band satellite data. The combination methods of SAR interferometry approach and the real-time WT depth monitoring system to identify degraded peatlands can be more efficient, faster, and accurate. The advantage of this research result shows that SAR interferometry analysis can reach blank spot areas that are not covered by the observation station of WT depth monitoring system. It also gives a benefit as a guide to select precise locations of observation stations related to degraded peatland and forest fire.
- Geosciences, Vol. 9, Pages 483: Sediment Supply and Hydrogeological Hazard in the Quebrada De Humahuaca (Province of Jujuy, Northwestern Argentina)—Rio Huasamayo and Tilcara Area
This paper describes the hydrogeological hazard in a reach of Quebrada de Humahuaca, (Upper Valley of Rio Grande de Jujuy, in the Argentine Andes), elected a World Heritage Site by UNESCO in 2003. Along the Quebrada, the Rio Huasamayo, flowing into the Rio Grande, formed a large alluvial fan where the village of Tilcara was built. The final reach of Rio Huasamayo is an artificial channel, embanked by unconsolidated material removed from the riverbed. The village is located in an area at a lower elevation with respect to the riverbed, still in aggradation; so it is affected by an evident hydrogeological hazard. The main cause of the riverbed aggradation is the enormous sediment supply from the slopes of the Rio Huasamayo basin. The aim of the paper is to estimate the soil loss on the slopes and the consequent sediment supply to the main stream, identifying the areas of the basin mostly affected by erosion processes that cause the aggradation of the Rio Huasamayo riverbed. In this case, due to the lack of hydrometeorological stations (monitoring rainfalls, temperature, flow rates, etc.), soil loss and sediment supply to the main stream cannot be estimated through the application of commonly used models in the literature (e.g., USLE, RUSLE, USPED). Here the Gavrilovic method (EPM) was applied in combination with the data of the CORINE Project, allowing the estimation of the volume of material exiting from the catchment. So the main supplying areas (sub-basins of the Rio Huasamayo) can be identified where focused interventions for the control of solid transport could be realized, to mitigate the process of riverbed aggradation.
- Geosciences, Vol. 9, Pages 482: Socio-Economic Impacts of Cyclone Aila on Migrant and Non-Migrant Households in the Southwestern Coastal Areas of Bangladesh
In 2009, the tropical cyclonic storm Aila hit 11 southwestern coastal districts in Bangladesh, which triggered migration. Many studies were conducted on the impact of Aila on southwestern coastal communities; however, no comparative study was done on migrant and non-migrant households. Therefore, this article set out to assess the impact of cyclone Aila on the socio-economic conditions of migrant and non-migrant households. The households that could not cope with the impact, resulting in at least one household member having to migrate to seek an alternative source of income, were considered migrant households. On the other hand, non-migrant households were considered as those where no one migrated. The unit of analysis was the households. The research was conducted in the Koyra and Shymnagar sub-districts of Khulna and Satkhira, respectively. Mixed-method analysis was carried out using quantitative data collected from 270 households through a survey and qualitative data through 2 focus group discussions, 12 key informant interviews, and informal discussions. Data were analyzed through a comparative analysis of the migrant and non-migrant households. The findings showed that migrant households were better equipped to recover from losses in terms of income, housing, food consumption, and loan repayments than non-migrant households. It can be argued that the options of migration or shifting livelihood are better strategies for households when dealing with climatic events. Furthermore, the outcome of this research could contribute to the growing body of knowledge in an area where there are evident gaps. The findings could support policymakers and researchers to understand the impacts of similar climatic events, as well as the necessary policy interventions to deal with similar kinds of climatic events in the future. The study could be useful for developing and refining policies to recover from losses as a result of the same types of climatic events.
- Geosciences, Vol. 9, Pages 481: Evaluation of the Gas Content in Archived Shale Samples: A Carbon Isotope Study
We examined 14 archived samples of shale for the chemical and 13C isotopic composition of residual gases produced as part of rock-crushing operations at a hammer mill. Results were compared with data on maturity from Rock-Eval pyrolysis and vitrinite reflectance measurements. The samples originated from three different formations (Mikulov Marls, Ostrava Formation, and Liteň Formation) located in the Czech Republic. For comparison, we examined a gas-prone shale sample from the Polish Silurian. We used changes in the chemical and isotopic composition of released gases to evaluate the isotope fractionation during gas loss and retroactively calculated the initial content of gas in the shale samples. The gas content estimates (in L of gas per ton of rock) correspond with the maturity parameters of the shales. Calculated isotope fractionation for the gas release was −3‰ for both methane and ethane. The archived samples primarily lost methane (up to 90%), with subsequent changes in the content of ethane and higher hydrocarbon levels.
- Geosciences, Vol. 9, Pages 480: Spatio-Temporal Relationships between Fumarolic Activity, Hydrothermal Fluid Circulation and Geophysical Signals at an Arc Volcano in Degassing Unrest: La Soufrière of Guadeloupe (French West Indies)
： Over the past two decades, La Soufrière volcano in Guadeloupe has displayed a growing degassing unrest whose actual source mechanism still remains unclear. Based on new measurements of the chemistry and mass flux of fumarolic gas emissions from the volcano, here we reveal spatio-temporal variations in the degassing features that closely relate to the 3D underground circulation of fumarolic fluids, as imaged by electrical resistivity tomography, and to geodetic-seismic signals recorded over the past two decades. Discrete monthly surveys of gas plumes from the various vents on La Soufrière lava dome, performed with portable MultiGAS analyzers, reveal important differences in the chemical proportions and fluxes of H2O, CO2, H2S, SO2 and H2, which depend on the vent location with respect to the underground circulation of fluids. In particular, the main central vents, though directly connected to the volcano conduit and preferentially surveyed in past decades, display much higher CO2/SO2 and H2S/SO2 ratios than peripheral gas emissions, reflecting greater SO2 scrubbing in the boiling hydrothermal water at 80–100 m depth. Gas fluxes demonstrate an increased bulk degassing of the volcano over the past 10 years, but also a recent spatial shift in fumarolic degassing intensity from the center of the lava dome towards its SE–NE sector and the Breislack fracture. Such a spatial shift is in agreement with both extensometric and seismic evidence of fault widening in this sector due to slow gravitational sliding of the southern dome sector. Our study thus provides an improved framework to monitor and interpret the evolution of gas emissions from La Soufrière in the future and to better forecast hazards from this dangerous andesitic volcano.
- Short-range-order minerals as powerful factors explaining deep soil organic carbon stock distribution: the case of a coffee agroforestry plantation on Andosols in Costa Rica
Short-range-order minerals as powerful factors explaining deep soil organic carbon stock distribution: the case of a coffee agroforestry plantation on Andosols in Costa Rica Tiphaine Chevallier, Kenji Fujisaki, Olivier Roupsard, Florian Guidat, Rintaro Kinoshita, Elias de Melo Viginio Filho, Peter Lehner, and Alain Albrecht SOIL, 5, 315–332, https://doi.org/10.5194/soil-5-315-2019, 2019 Soil organic carbon (SOC) is the largest terrestrial C stock. Andosols of volcanic areas hold particularly large stocks (e.g. from 24 to 72 kgC m−2 in the upper 2 m of soil) as determined via MIR spectrometry at our Costa Rican study site: a 1 km2 basin covered by coffee agroforestry. Andic soil properties explained this high variability, which did not correlate with stocks in the upper 20 cm of soil. Topography and pedogenesis are needed to understand the SOC stocks at landscape scales.
- Modelling soil and landscape evolution – the effect of rainfall and land use change on soil and landscape patterns
Modelling soil and landscape evolution – the effect of rainfall and land use change on soil and landscape patterns W. Marijn van der Meij, Arnaud J. A. M. Temme, Jakob Wallinga, and Michael Sommer SOIL Discuss., https//doi.org/10.5194/soil-2019-82,2019 Manuscript under review for SOIL (discussion: open, 0 comments) We developed a model to simulate long-term development of soils and landscapes under varying rainfall and land-use conditions to quantify the temporal variation of soil patterns. In natural landscapes, rainfall amount was the dominant factor influencing soil variation, while for agricultural landscapes, landscape position became the dominant factor due to tillage erosion. Our model shows potential for simulating past and future developments of soils in various landscapes.
- Oblique geographic coordinates as covariates for digital soil mapping
Oblique geographic coordinates as covariates for digital soil mapping Anders Bjørn Møller, Amélie Marie Beucher, Nastaran Pouladi, and Mogens Humlekrog Greve SOIL Discuss., https//doi.org/10.5194/soil-2019-83,2019 Manuscript under review for SOIL (discussion: open, 0 comments) Decision trees have become a widely adapted tool for mapping soil properties in geographic space. However, it is problematic to implement geographic relationships in the models. We present a method, which uses coordinates along several axes tilted at oblique angles in the models. We test this method for an agricultural field in Denmark. The results show that the new method is as accurate as other proposed alternatives, has a computational advantage and is flexible and interpretable.
- 15N gas-flux method to determine N2 emission and N2O pathways: a comparison of different tracer addition approaches
15N gas-flux method to determine N2 emission and N2O pathways: a comparison of different tracer addition approaches Dominika Lewicka-Szczebak and Reinhard Well SOIL Discuss., https//doi.org/10.5194/soil-2019-64,2019 Manuscript under review for SOIL (discussion: open, 0 comments) This study aimed at comparison of various experimental strategies for incubating soil samples to determine the N2 flux. Such experiments require addition of isotope tracer, i.e., nitrogen fertilizer enriched in heavy nitrogen isotopes (15N). Here we compared the impact of soil homogenisation and mixing with the tracer and tracer injection to the intact soil cores. The results are well comparable, both techniques would provide similar conclusions on the magnitude of N2 flux.
- Elemental Composition, Leachability Assessment and Spatial Variability Analysis of Surface Soils in the Mugan Plain in the Republic of Azerbaijan
Elemental Composition, Leachability Assessment and Spatial Variability Analysis of Surface Soils in the Mugan Plain in the Republic of Azerbaijan Junho Han, Zaman Mammadov, Elton Mammadov, Seoyeon Lee, Jisuk Park, Garib Mammadov, Guliyev Elovsat, and Hee-Myong Ro SOIL Discuss., https//doi.org/10.5194/soil-2019-66,2019 Manuscript under review for SOIL (discussion: open, 0 comments) The Republic of Azerbaijan has suffered from low agricultural productivity caused by soil salinization and erosion, and limited and insufficient soil data are available for economic and political reasons. This study has provided a foundation for the international study of Azerbaijani soil by sharing soil and salinization data with researchers worldwide and can help to diminish or solve agricultural problems in both Azerbaijan and neighboring countries suffering from soil salinization.