MAP OF SOIL UNITS AND SURFACE LITHOLOGY AS A CONTRIBUTION TO THE OVERALL PROJECT RISK MANAGEMENT IN URBAN SPACES - MÉRIDA PHASE, VENEZUELA

La investigación llevada a cabo dentro del proyecto intitulado “Gestión integral de riesgos en espacios urbanos (Fase Mérida)” enmarcado en el macro proyecto Misión Ciencias, tuvo como objetivo en su componente geológico_ geomorfológico_ geotécnico elaborar un mapa de susceptibilidad ante movimientos en masa en el área metropolitana del Municipio Libertador del estado Mérida, el cual resulto de la integración de cinco variables condicionantes a la estabilidad: pendiente, vegetación, geomorfología, cinemática y unidades de suelo, y litología superficial. Para efectos del artículo se expondrá una de las principales variables utilizadas, el mapa de unidades de suelo y litología superficial. Este mapa representa una propuesta a ser incluida dentro de los mapas de susceptibilidad, ya que permite cartografiar la distribución areal de los materiales geológicos superficiales en base a su estado físico-geomecánico, condición no considerada en los análisis clásicos. En función de esta nueva metodología, se logró caracterizar diecisiete unidades de material superficial, considerando: resistencia, grado de fracturamiento, meteorización y comportamiento geomecánico de los materiales, estableciéndose además niveles de propensión a la inestabilidad. Research carried out within the project entitled “Integrated risk management in urban areas (Mérida Phase)” framed in Science Mission project, had as main objective (geological – geotechnical- geomorphological component) produce a map susceptibility to mass movements in the metropolitan area of Libertador Municipality of Mérida, which resulted from the integration of five conditions to the stability variables: slope, vegetation, geomorphology, kinematics and ground units and surface lithology. For purposes of the article will present one of the main variables used, the map units of soil and surface lithology. This map represents a proposal to be included within the susceptibility maps, allowing mapping the distribution area of surface geological materials based on their physical and geomechanical state, condition not considered in the classical analysis. Based on this new method, it was possible to characterize seventeen units surface material, considering: resistance, degree of fracturing, weathering and geomechanical behavior of materials, also establishing levels of propensity to instability

MAP OF SOIL UNITS AND SURFACE LITHOLOGY AS A CONTRIBUTION TO THE OVERALL PROJECT RISK MANAGEMENT IN URBAN SPACES - MÉRIDA PHASE, VENEZUELA

La investigación llevada a cabo dentro del proyecto intitulado “Gestión integral de riesgos en espacios urbanos (Fase Mérida)” enmarcado en el macro proyecto Misión Ciencias, tuvo como objetivo en su componente geológico_ geomorfológico_ geotécnico elaborar un mapa de susceptibilidad ante movimientos en masa en el área metropolitana del Municipio Libertador del estado Mérida, el cual resulto de la integración de cinco variables condicionantes a la estabilidad: pendiente, vegetación, geomorfología, cinemática y unidades de suelo, y litología superficial. Para efectos del artículo se expondrá una de las principales variables utilizadas, el mapa de unidades de suelo y litología superficial. Este mapa representa una propuesta a ser incluida dentro de los mapas de susceptibilidad, ya que permite cartografiar la distribución areal de los materiales geológicos superficiales en base a su estado físico-geomecánico, condición no considerada en los análisis clásicos. En función de esta nueva metodología, se logró caracterizar diecisiete unidades de material superficial, considerando: resistencia, grado de fracturamiento, meteorización y comportamiento geomecánico de los materiales, estableciéndose además niveles de propensión a la inestabilidad. Research carried out within the project entitled “Integrated risk management in urban areas (Mérida Phase)” framed in Science Mission project, had as main objective (geological – geotechnical- geomorphological component) produce a map susceptibility to mass movements in the metropolitan area of Libertador Municipality of Mérida, which resulted from the integration of five conditions to the stability variables: slope, vegetation, geomorphology, kinematics and ground units and surface lithology. For purposes of the article will present one of the main variables used, the map units of soil and surface lithology. This map represents a proposal to be included within the susceptibility maps, allowing mapping the distribution area of surface geological materials based on their physical and geomechanical state, condition not considered in the classical analysis. Based on this new method, it was possible to characterize seventeen units surface material, considering: resistance, degree of fracturing, weathering and geomechanical behavior of materials, also establishing levels of propensity to instability

Evaluation of Drought Indices Based on Thermal Remote Sensing of Evapotranspiration over the Continental United States

The reliability of standard meteorological drought indices based on measurements of precipitation is limited by the spatial distribution and quality of currently available rainfall data. Furthermore, they reflect only one component of the surface hydrologic cycle, and they cannot readily capture nonprecipitation-based moisture inputs to the land surface system (e.g., irrigation) that may temper drought impacts or variable rates of water consumption across a landscape. This study assesses the value of a new drought index based on remote sensing of evapotranspiration (ET). The evaporative stress index (ESI) quantifies anomalies in the ratio of actual to potential ET (PET), mapped using thermal band imagery from geostationary satellites. The study investigates the behavior and response time scales of the ESI through a retrospective comparison with the standardized precipitation indices and Palmer drought index suite, and with drought classifications recorded in the U.S. Drought Monitor for the 2000–09 growing seasons. Spatial and temporal correlation analyses suggest that the ESI performs similarly to short-term (up to 6 months) precipitation-based indices but can be produced at higher spatial resolution and without requiring any precipitation data. Unique behavior is observed in the ESI in regions where the evaporative flux is enhanced by moisture sources decoupled from local rainfall: for example, in areas of intense irrigation or shallow water table. Normalization by PET serves to isolate the ET signal component responding to soil moisture variability from variations due to the radiation load. This study suggests that the ESI is a useful complement to the current suite of drought indicators, with particular added value in parts of the world where rainfall data are sparse or unreliable

Thermal-Based Evaporative Stress Index for Monitoring Surface Moisture Depletion

The standard suite of indicators currently used in operational drought monitoring reflects anomalous conditions in several major components of the hydrologic budget—representing deficits in precipitation, soil moisture content, runoff, surface and groundwater storage, snowpack, and streamflow. In principle, it is useful to have a diversity of indices because drought can assume many forms (meteorological, agricultural, hydrological, and socioeconomic), over broad ranges in timescale (weeks to years), and with varied impacts of interest to different stakeholder groups. Farmers, for example, may be principally interested in soil moisture deficits, river forecasters will focus on streamflow fluctuations, and water managers will be concerned with longer-term stability in municipal water supply and reservoir levels. Only recently has actual evapotranspiration (ET) been considered as a primary indicator of drought conditions (e.g., Anderson et al., 2007b; Labedzki and Kanecka- Geszke, 2009; Li et al., 2005; Mo et al., 2010). ET is a valuable drought indicator because it reflects not only moisture availability but also the rate at which water is being consumed. Because transpiration (T) and carbon uptake by vegetation are tightly coupled through stomatal exchange, ET anomalies are indicative of vegetation health and growing conditions. In addition, the importance of so-called flash droughts is becoming increasingly evident, where hot, dry, and windy atmospheric conditions can lead to unusually rapid soil moisture depletion and, in some cases, devastating crop failure. Such events cannot be easily identified using local precipitation anomalies but should have a detectable ET signature

Detecting the effects of hydrocarbon pollution in the Amazon forest using hyperspectral satellite images

The global demand for fossil energy is triggering oil exploration and production projects in remote areas of the world. During the last few decades hydrocarbon production has caused pollution in the Amazon forest inflicting considerable environmental impact. Until now it is not clear how hydrocarbon pollution affects the health of the tropical forest flora. During a field campaign in polluted and pristine forest, more than 1100 leaf samples were collected and analysed for biophysical and biochemical parameters. The results revealed that tropical forests exposed to hydrocarbon pollution show reduced levels of chlorophyll content, higher levels of foliar water content and leaf structural changes. In order to map this impact over wider geographical areas, vegetation indices were applied to hyperspectral Hyperion satellite imagery. Three vegetation indices (SR, NDVI and NDVI705) were found to be the most appropriate indices to detect the effects of petroleum pollution in the Amazon forest

A global spectral library to characterize the world's soil

Soil provides ecosystem services, supports human health and habitation, stores carbon and regulates emissions of greenhouse gases. Unprecedented pressures on soil from degradation and urbanization are threatening agro-ecological balances and food security. It is important that we learn more about soil to sustainably manage and preserve it for future generations. To this end, we developed and analyzed a global soil visible-near infrared (vis-NIR) spectral library. It is currently the largest and most diverse database of its kind. We show that the information encoded in the spectra can describe soil composition and be associated to land cover and its global geographic distribution, which acts as a surrogate for global climate variability. We also show the usefulness of the global spectra for predicting soil attributes such as soil organic and inorganic carbon, clay, silt, sand and iron contents, cation exchange capacity, and pH. Using wavelets to treat the spectra, which were recorded in different laboratories using different spectrometers and methods, helped to improve the spectroscopic modelling. We found that modelling a diverse set of spectra with a machine learning algorithm can find the local relationships in the data to produce accurate predictions of soil properties. The spectroscopic models that we derived are parsimonious and robust, and using them we derived a harmonized global soil attribute dataset, which might serve to facilitate research on soil at the global scale. This spectroscopic approach should help to deal with the shortage of data on soil to better understand it and to meet the growing demand for information to assess and monitor soil at scales ranging from regional to global. New contributions to the library are encouraged so that this work and our collaboration might progress to develop a dynamic and easily updatable database with better global coverage. We hope that this work will reinvigorate our community's discussion towards larger, more coordinated collaborations. We also hope that use of the database will deepen our understanding of soil so that we might sustainably manage it and extend the research outcomes of the soil, earth and environmental sciences towards applications that we have not yet dreamed of

In-field detection and quantification of Septoria tritici blotch in diverse wheat germplasm using spectral-temporal features

Hyperspectral remote sensing holds the potential to detect and quantify crop diseases in a rapid and non-invasive manner. Such tools could greatly benefit resistance breeding, but their adoption is hampered by i) a lack of specificity to disease-related effects and ii) insufficient robustness to variation in reflectance caused by genotypic diversity and varying environmental conditions, which are fundamental elements of resistance breeding. We hypothesized that relying exclusively on temporal changes in canopy reflectance during pathogenesis may allow to specifically detect and quantify crop diseases whilst minimizing the confounding effects of genotype and environment. To test this hypothesis, we collected time-resolved canopy hyperspectral reflectance data for 18 diverse genotypes on infected and disease-free plots and engineered spectral-temporal features representing this hypothesis. Our results confirm the lack of specificity and robustness of disease assessments based on reflectance spectra at individual time points. We show that changes in spectral reflectance over time are indicative of the presence and severity of septoria tritici blotch (STB) infections. Furthermore, the proposed time-integrated approach facilitated the delineation of disease from physiological senescence, which is pivotal for efficient selection of STB-resistant material under field conditions. A validation of models based on spectral-temporal features on a diverse panel of >300 wheat genotypes offered evidence for the robustness of the proposed method. This study demonstrates the potential of time-resolved canopy reflectance measurements for robust assessments of foliar diseases in the context of resistance breeding