Search results for "Computers in Earth Science"
showing 10 items of 323 documents
Use of physicochemical processing in treating urban waste waters
1994
The principal objective of the present study was to compare two clearly defined purification processes in two stages: the periods 1985–1987 (conventional) and 1988–1990 (physico‐chemical). In general, the mean concentrations obtained were lower in the second period. A z‐test for comparing means was applied, but no significant correlation was observed (p ≤ 0.05). The mean concentrations obtained (with some exceptions) are lower in the second period. With the passing of time, the total volume of sewage flow has increased, and hence the load of contaminants has become diluted. The use of physico‐chemical treatment prior to biological processing may be the cause of the increase in cost.
Climate variability and agricultural production efficiency: evidence from Ethiopian farmers
2020
It is known that climate and weather variability have negative impacts on agricultural production efficiency. The aim of this study is to analyse the impact of climatic variables on farms’ efficiency in Ethiopia making use of nationally representative datasets from Living Standards Measurement Study–Integrated Surveys on Agriculture (LSMS-ISA) 2011/2012. By using the Stochastic Frontier Approach, we estimate simultaneously the farmers’ optimal production function and technical inefficiency equations, taking into account unobserved heterogeneity of farmers. Our main findings show that climate change variables have a positive effect on households’ efficiency but the impact depends on the diff…
Empirical relationships for monitoring water quality of lakes and reservoirs through multispectral images
2014
Remote sensing techniques can be used to estimate water quality variables such as chlorophyll ${\mbi a}$ , total suspended particles, and water transparency. This paper describes empirical algorithms for the estimation of these variables using Landsat Thematic Mapper (TM) data. Ground data were taken from several Spanish lakes covering a variety of trophic statuses, ranging from oligotrophic to hypereutrophic. The studied lakes were the Albufera de Valencia and lakes and ponds of the Southeast Regional Park in Madrid. Empirical equations were obtained to estimate chlorophyll ${\mbi a}$ from the ratio in reflectance values between bands 2 and 4 of TM ( $\bf{ R^2 \, {\mmb =}\, 0.66}$ , ${\bf …
Early-stage thermal performance design of thermo-active walls implemented in underground infrastructures
2022
Abstract Energy geostructures (EGs) represent an innovative technology in the sustainable energy agenda and are useful for satisfying the energy needs of the built environment. They are usually involving geostructures such as piles, walls, tunnels, shafts, and sewers. The application of such technology to infrastructure projects may have considerable thermal potential because of the large surfaces that can be thermally activated. This study focuses on thermo-active walls (energy walls, EWs), which are retaining structures used to sustain the sides of excavations. Key features related to their thermal design are examined, and a design methodology is proposed. The heat-exchange modes involvin…
Experimental analysis of a thermoactive underground railway station
2022
Little is known about the real energy potential of thermoactive underground infrastructures, such as railway stations, that can act as a heating/cooling provider for the built environment. This study presents the results of thermomechanical full-scale in situ testing and numerical analysis of a thermoactive underground train station. The thermal performance and related geostructural impact of a portion of the new underground energy infrastructure (UEI) installed at the Lancy-Bachet train station in Geneva (Switzerland) are analyzed. Heating and cooling tests simulating real operative geothermal conditions are considered. Particular attention is given to ((i) the monitored wall-tunnel hydrot…
Land cover classification of VHR airborne images for citrus grove identification
2011
Abstract Managing land resources using remote sensing techniques is becoming a common practice. However, data analysis procedures should satisfy the high accuracy levels demanded by users (public or private companies and governments) in order to be extensively used. This paper presents a multi-stage classification scheme to update the citrus Geographical Information System (GIS) of the Comunidad Valenciana region (Spain). Spain is the first citrus fruit producer in Europe and the fourth in the world. In particular, citrus fruits represent 67% of the agricultural production in this region, with a total production of 4.24 million tons (campaign 2006–2007). The citrus GIS inventory, created in…
The impact of climate change on the distribution of rural income in Ethiopia
2018
Recent evidence suggests that global climate change is likely to increase the incidence of environmental disasters, as well as the frequency of extreme weather events. As a result, it is generally recognized that climate and weather variability has negative impacts on households’ welfare relying mainly on agriculture. In Ethiopia, 95% of the population depends on rain-fed agriculture and consequently the economic impact of climate change is crucial for small-scale farmers’ food security and welfare. The objective of this study is to provide a comprehensive analysis of the impact of climate change on rural households’ welfare in Ethiopia by using a Quantile Regression (QR) analysis. The main…
Phenology Estimation From Meteosat Second Generation Data
2013
Many studies have focused on land surface phenology, for example as a means to characterize both water and carbon cycles for climate model inputs. However, the Spinning Enhanced Visible Infra-Red Imager (SEVIRI) sensor onboard Meteosat Second Generation (MSG) geostationary satellite has never been used for this goal. Here, five years of MSG-SEVIRI data have been processed to retrieve Normalized Difference Vegetation Index (NDVI) daily time series. Due to existing gaps as well as atmospheric and cloud contamination in the time series, an algorithm based on the iterative Interpolation for Data Reconstruction (IDR) has been developed and applied to SEVIRI NDVI time series, from which phenologi…
Learning main drivers of crop progress and failure in Europe with interpretable machine learning
2021
Abstract A wide variety of methods exist nowadays to address the important problem of estimating crop yields from available remote sensing and climate data. Among the different approaches, machine learning (ML) techniques are being increasingly adopted, since they allow exploiting all the information on crop progress and environmental conditions and their relations with crop yield, achieving reliable and accurate estimations. However, interpreting the relationships learned by the ML models, and hence getting insights about the problem, remains a complex and usually unexplored task. Without accountability, confidence and trust in the ML models can be compromised. Here, we develop interpretab…
Mapping snow density through thermal inertia observations
2023
Snow, as a fundamental reservoir of freshwater, is a crucial natural resource. Specifically, knowledge of snow density spatial and temporal variability could improve modelling of snow water equivalent, which is relevant for managing freshwater resources in context of ongoing climate change. The possibility of estimating snow density from remote sensing has great potential, considering the availability of satellite data and their ability to generate efficient monitoring systems from space. In this study, we present an innovative method that combines meteorological parameters, satellite data and field snow measurements to estimate thermal inertia of snow and snow density at a catchment scale.…