Search results for "Spatial"
showing 10 items of 2121 documents
Variabilidad espacial de los cambios de cauce en una rambla mediterránea en las seis últimas décadas (1946-2006)
2014
An analysis of morphological changes during the last six decades is presented for the Rambla de Cervera, a Mediterranean ephemeral stream located in the eastern sector of the Iberian Mountain Range. The studied channel (16.5 km) has two contrasted sectors: a horst confined sector (5.5 km) and a graben sector (11 km). Channel changes were analysed through the analysis of aerial photographs, with geographical information systems (GIS) and comparison of topographic surveys made with a GPS-RTK. Between 1946 and 2006 the Rambla de Cervera, underwent channel adjustments comparable to those observed in other Mediterranean rivers. The gravel channel markedly narrowed, losing width (68.5%) and chann…
A δ18O isoscape for the shallow groundwater in the Baltic Artesian Basin
2016
The study presents a shallow groundwater isoscape for the Baltic region, which covers the major part of the Baltic Artesian Basin (BAB). BAB is an important palaeogroundwater reservoir, but prior to this study, little has been known about the spatial variability of δD and δ18O values in modern precipitation input across the region. To overcome this limitation, we hypothesized that the isotopic composition of shallow groundwater in the BAB could be used as a proxy for the mean weighted annual isotopic composition of local precipitation. However, the results of the study reveal many clear discrepancies between the isotopic composition of precipitation and shallow groundwater in the area. The …
Water Level Measurement Locations for Coastal Aquifer Management
2003
The coefficient of variation of the optimal cost (CVOC) method is applied to the Acqua dei Corsari coastal aquifer in Sicily's north coast to find the best point for a new water-level measurement location. The purpose of collecting data from the new measurement location is to reduce uncertainty associated with a stochastic management model for salt-water intrusion control. Assuming that uncertainty mainly stems from spatial variability of permeability, the structural parameters of the stochastic spatial permeability field are estimated using data from a nearby aquifer with similar geological properties. It is first shown through sensitivity analysis that the lack of previous information inh…
Soil erosion and hydrology of the western Mediterranean badlands throughout rainfall simulation experiments: A review
2013
Abstract Rainfall simulation experiments are widely used in geomorphological research in badland areas. This technique contributed significantly to our understanding of badland geomorphology in the Mediterranean belt. Due to the different types of simulated rainfall applied and the variable size of the plots a review of the State-of-the-Art is necessary. This study confirmed that rainfall simulations are well suited to (i) analyse runoff-infiltration processes and sediment detachment within badlands, and (ii) to establish the factors determining the hydrological and erosion response at interrill scale in badland areas. The hydrological response of badlands is characterized by rapid response…
Statistical distribution of soil loss and sediment yield at Sparacia experimental area, Sicily
2010
Abstract An analysis of the statistical distribution of event soil loss was carried out using the data collected in the period 1999–2008 at the microplots and plots of the Sparacia experimental area (Sicily, Italy). For a given microplot size, the analysis allowed to establish that the soil loss frequency distribution was skewed. Using the soil loss normalized by the event mean value, the analysis also showed that the frequency distributions corresponding to different microplot and plot sizes were overlapping, i.e. all distributions were extracted by the same statistical population. The developed analysis allowed to suggest that the soil loss of a given return period can be estimated using …
Spatial distribution and temporal changes in river water temperature in the Baltic States
2017
Abstract The thermal regime of rivers in the Baltic States (Estonia, Latvia and Lithuania) is not sufficiently studied. The presented research describes the spatial distribution and temporal variation of river water temperature (WT) in the Baltic States using a unified methodology. The object of the research is the WT of rivers during the warm season (May–October) and the warmest month of the year (July). The contour maps of WT were compiled for the rivers of the Baltic States using data series for the period 1961–1990 from 17 water measuring stations in Estonia (EST), 36 stations in Latvia (LV) and 40 stations in Lithuania (LT). These maps allow the evaluation of WT for the unmonitored riv…
Applying the bootstrap technique for studying soil redistribution by caesium-137 measurements at basin scale
2000
Abstract The use of the bootstrap technique to estimate the reference level of137 Cs in an uneroded site is tested. The analysis is developed using 137Cs measurements made in a small experimental Sicilian basin. In the reference area the 137Cs activity is normally distributed with a known sample mean value, m equal to 94.4 mBq cm−2. The influence of137 Cs reference site sampling was determined generating samples having a fixed size, N and six different values of the sample coefficient of variation, CV, by a Monte Carlo technique. Then, for each size N, the probability distribution of the mean μ of the sequences generated by Monte Carlo technique is defined. The soil redistribution is determ…
Hydrogeological hazards and weather events: Triggering and evolution of shallow landslides
2014
Abstract Landslides are the most intense and serious manifestations of the degradation of slopes and they are the main causes of geological hazard when they, directly or indirectly, involving towns and infrastructures. They are a global environment problem; there are several examples that have produced untold damages and loss of human lives in many parts of the world. In 1920 the landslides mobilization, as a result of a strong earthquake in China, in the province of Kansu, killed 200,000 people; in 1938 fast debris flow, triggered by heavy rainfalls in Japan, caused the death of 600 people; in 1963 in Italy the Vajont disaster caused the death of 1,899 people, as a result of a landslide lo…
Establishing a soil loss threshold for limiting rilling
2015
In this paper a frequency analysis of event soil loss measurements collected in the period 1999–2012 at the microplots and plots of the Sparacia Experimental Area in Sicily, southern Italy, was developed. The analysis was carried out using the annual maximum soil loss measurements normalized by the mean soil loss measured at a given temporal and spatial scale. The empirical frequency distribution of the normalized variable was well fitted by two Gumbel’s theoretical probability distributions discriminated by a value of the normalized variable equal to 2. This last value discriminates between the relatively low and frequent values of the normalized variable and the high and rare ones. The an…
Experimental investigation on dispersion mechanisms in rigid and flexible vegetated beds
2018
Vegetation in channels strongly affects flow structure and turbulence, with consequences on the hydrological storage of nutrients and chemical tracers, the shelter of stream biota as well as the trapping or transport of sediments. At the same time, all these phenomena are inevitably subjected to alteration of hydrological conditions in fluvial systems due to climate change. The present study intends to provide a thorough investigation into the processes of transport and dispersion induced by flow turbulence within the vegetation structure. Specifically, velocity measurements in vegetated channels were intensively conducted and analyzed in the case of both flexible submerged and rigid emerge…