Search results for "Environmental Biotechnology"
showing 10 items of 568 documents
An assessment of the BEST procedure to estimate the soil water retention curve: A comparison with the evaporation method
2018
The Beerkan Estimation of Soil Transfer parameters (BEST) procedure is an attractive, easy, robust, and inexpensive way for a complete soil hydraulic characterization but testing the ability of this procedure to estimate the water retention curve is necessary as relatively little information is available in the literature. In this investigation the soil water retention curve was predicted for four differently textured soils by applying three existing BEST algorithms (i.e., slope, intercept and steady) and the results compared with those measured by the standard Wind evaporation method. A sensitivity analysis of the infiltration constants, beta and gamma, was also carried out and their impac…
How and why does willow biochar increase a clay soil water retention capacity?
2018
Addition of biochar into a soil changes its water retention properties by modifying soil textural and structural properties. In addition, internal micrometer-scale porosity that is able to directly store readily plant available water affects soil water retention properties. This study shows how precise knowledge of the internal micrometer-scale pore size distribution of biochar can deepen the understanding of the biochar-water interactions in soils. The micrometer-scale porosity of willow biochar was quantitatively and qualitatively characterized using X-ray tomography, 3D image analysis and Helium ion microscopy. The effect of biochar application on clay soil water retention was studied by…
Saturated Soil Hydraulic Conductivity
2016
This chapter deals primarily with field measurement of saturated soil hydraulic conductivity, K fs . Well or borehole permeameter techniques, specifically developed for subsurface soil measurements above the water table, are initially illustrated. Particular attention is paid to establishment of steady flow under constant head in an uncased borehole, widely developed both theoretically and experimentally in the last 30 years. Situations involving cased boreholes, transient flow, or falling head processes are then described. These variants have received a renewed interest in the last few years. New data analysis procedures have been proposed and this circumstance allows us to obtain subsurfa…
A BMA Analysis to Assess the Urbanization and Climate Change Impact on Urban Watershed Runoff
2016
Abstract A reliable planning of urban drainage systems aimed at the mitigation of flooding, should take into account the possible change over time of impervious cover in the urban watershed and of the climate features. The present study proposes a methodology to analyze the changing in runoff response for a urban watershed accounting several plausible future states of new urbanization and climate. To this aim, several models simulating the evolution scenario of impervious watershed area and of climate change were adopted. However, it is known that an evolution scenario represents only one of all possible occurrence and it is not necessary the true future state, therefore it is needed to fin…
Extreme dry spells over the Mediterranean Basin during the wet season: assessment of HyMeX/Med-CORDEX regional climate simulations (1979-2009).
2018
16 pages; International audience; Exceptional dry spells, in this study referred to as very long dry spells (VLDS), are natural hazards to which the Mediterranean region is extremely vulnerable, with socio‐economic and environmental impacts. In this study, they are characterized in terms of location, spatial extent, duration, temporal variability and associated atmospheric circulations. The main objective is to assess the performance of five HyMeX/Med‐CORDEX regional climate simulations to detect and reproduce VLDS in comparison with the E‐OBS observed daily gridded data. Models accurately reproduce the occurrence of precipitation around the Mediterranean Basin, and therefore the occurrence…
On the projected increase of Sahel rainfall during the late rainy season
2016
Thirteen CMIP5 models are used to analyse changes in climate over the West African monsoon region between the near future (2031–2070 under the RCP4.5 emission scenario), and a control period (1960–1999 under the historical emission scenario), with a focus on the late rainy season. The monsoon circulation is projected to strengthen and to shift northward leading to more rainfall during the Sahelian season. The results show an increase of the Rainfall amounts in September–October and a delay in the monsoon withdrawal. The increased moisture that fuels the rainfall anomalies is associated with an increase in moisture flux convergence and with local moisture recycling. The moisture transport do…
Extreme dry spell detection and climatology over the Mediterranean Basin during the wet season
2016
The E-OBS precipitation gridded data set v.10.0 is used to detect very long dry spell (VLDS) events over the entire Mediterranean Basin for the 1957–2013 period, during the wet season (September to April). The main objective is to characterize these events as climatic objects, in terms of location, spatial extent, duration, and temporal variability. In this study, 76 VLDS events were detected in the Mediterranean Basin and grouped into four spatial patterns: scattered localized (with 25 events), northeast Mediterranean (11 events), West Mediterranean (15 events), and southeast Mediterranean (25 events). Each pattern shows seasonality in events. Most of the scattered localized, northeast, an…
Droughts Over Amazonia in 2005, 2010, and 2015: A Cloud Cover Perspective
2018
Amazon forests experienced recent severe droughts in an anomalous short period induced by different mechanisms and had different length periods and spatial patterns. Droughts of 2005 and 2010 were attributed to anomalous Sea Surface Temperature (SST) over the Tropical North Atlantic (TNA) during the dry season, but the 2010 drought was more severe and remained for a longer period because it was also induced in late 2009 by a moderate to strong El Niño (EN). Drought in 2015 led to unprecedented warming and extreme soil moisture deficits over some regions, and it was attributed to a very strong EN. Several studies analyzed these drought events regarding different climatic factors such as anom…
Applying Numerical Weather Prediction Models to the Production of New European Wind Atlas : Sensitivity studies of the wind climate to the planetary …
2018
Reliable and precise information about the wind speed climate is crucial for the development of wind energy. Meteorological processes in the mesoscale (2 – 200 km) can be represented using Numerical Weather Prediction (NWP) models such as the Weather Research and Forecast model (WRF), but before their application for creating wind energy atlases, their results and sensitivity to modelling parameters should be investigated. Here the WRF model wind speed results for the year 2015 for the Baltic Sea region are investigated, and the effect of the planetary boundary layer parametrization scheme is analyzed.
Dip Phenomenon in High-Curved Turbulent Flows and Application of Entropy Theory
2018
The estimation of velocity profile in turbulent open channels is a difficult task due to the significant effects of the secondary flow. The present paper investigates the mechanism of the velocity-dip phenomenon, whereby the location of the maximum velocity appears to be below the free surface. Previous studies conducted in straight channels relate the mechanism of the velocity-dip phenomenon to secondary flow induced by anisotropy of turbulence. This work focuses on high-curved channels where the secondary motion, which is also induced by the channel’s curvature, evolves along the bend. The width-to-depth ratio, B/h, is one of the most important parameters that are affecting the secondary …