Search results for "hydrology"
showing 10 items of 1041 documents
Perfluoroalkyl substances in the Ebro and Guadalquivir river basins (Spain).
2015
Mediterranean rivers are characteristically irregular with changes in flow and located in high population density areas. This affects the concentration of pollutants in the aquatic environments. In this study, the occurrence and sources of 21 perfluoroalkyl substances (PFASs) were determined in water, sediment and biota of the Ebro and Guadalquivir river basins (Spain). In water samples, of 21 analytes screened, 11 were found in Ebro and 9 in Guadalquivir. In both basins, the most frequents were PFBA, PFPeA and PFOA. Maximum concentration was detected for PFBA, up to 251.3ngL-1 in Ebro and 742.9ngL-1 in Guadalquivir. Regarding the sediments, 8 PFASs were detected in the samples from Ebro an…
Coastal Evolution in a Mediterranean Microtidal Zone: Mid to Late Holocene Natural Dynamics and Human Management of the Castellò Lagoon, NE Spain
2016
We present a palaeoenvironmental study of the Castelló lagoon (NE Spain), an important archive for understanding long-term interactions between dynamic littoral ecosystems and human management. Combining geochemistry, mineralogy, ostracods, diatoms, pollen, non-pollen palynomorphs, charcoal and archaeo-historical datasets we reconstruct: 1) the transition of the lagoon from a marine to a marginal environment between ~3150 cal BC to the 17th century AD; 2) fluctuations in salinity; and 3) natural and anthropogenic forces contributing to these changes. From the Late Neolithic to the Medieval period the lagoon ecosystem was driven by changing marine influence and the land was mainly exploited …
The role of historic and climatic factors in the distribution of crustacean communities in Iberian Mediterranean ponds
2013
SUMMARY 1. We studied 140 freshwater ponds in eastern Spain spanning a wide range of water source, hydroperiod and regional heterogeneity attributable to orographic and climatic differences. Our aim was to provide a typology for Mediterranean ponds using crustacean assemblages and to find key environmental thresholds that define these pond types. 2. To search for the environmental variables that define these communities, two complementary analyses were used: correspondence analyses (CA) and multivariate regression trees (MRT). We found a high level of specificity of crustaceans defining the different pond types. Three ponds, which were not associated with any of the large set of environment…
Multi-temporal Forest Cover Change and Forest Density Trend Detection in a Mediterranean Environment
2015
The loss of forests along with the various types of shrubs in the Mediterranean region is seen as an important driver of climate change and has been repeatedly related with the observed land degradation and desertification in the region. Nevertheless, the extent of woody perennial vegetation cover (WPVC) and its density remain largely unclear. Here, we apply a series of algorithms and methods operationally used in Australia for large-scale WPVC mapping and monitoring and demonstrate their applicability in the Mediterranean region using a Spanish area as the trial site. Five Landsat TM and ETM+ images from various dates spanning 14 years are used to map changes in the extent of WPVC and to i…
MARIOLA: a model for calculating the response of mediterranean bush ecosystem to climatic variations
1995
Abstract The paper summarizes the bush ecosystem model developed for assessing the effects of climatic change on the behaviour of mediterranean bushes assuming that temperature, humidity and rain-fall are the basic dimensions of the niche occupied by shrub species. In this context, changes in the monthly weather pattern serve only to outline the growth conditions due to the nonlinearity of response of shrubs to climatic factors. The plant-soil-atmosphere system is described by means of ordinary non-linear differential equations for the state variables: green biomass, woody biomass, the residues of green and woody biomasses, faecal detritus of mammals on the soil, and the total organic matte…
The erosional response of Calcareous soils along a climatological gradient in Southeast Spain
1998
Abstract The erosional response of calcareous soils along a climatological gradient in Alicante, SE Spain was studied. The erosional response was defined in terms of indicators obtained from field rainfall simulation experiments and laboratory studies of soil aggregation. Measurements were made at seven sites on limestones and marls between Benidorm with an annual average rainfall of 400 mm yr −1 and Coll de Rates (annual rainfall 900 mm yr −1 ). The sites were on matorral vegetation affected to varying intensities by grazing and fire. At the seven locations, soil aggregation was studied by sieving, by the single water drop test and by a Microscan particle-sizer. Rainfall simulation experim…
Scale effects on plot runoff and soil erosion in a mediterranean environment
2017
Explaining scale effects for runoff and erosion improves our understanding of hydrological and erosion processes. In this investigation, plot-scale effects on event runoff per unit area, Qe, sediment concentration, Ce, and soil loss per unit area, SLe, were checked at the Sparacia (Italy) site. Similar information on the scale effects was obtained with different dependent variables, i.e., individual values of Qe, Ce, and SLe for each plot or the mean of their replicated values, and scale indicators, i.e., plot length, l, or plot area, A. The most common result, occurring for 57 to 62% of the events depending on the considered variable, was the lack of any scale effect. When scale effects we…
The effect of ant mounds on overland flow and soil erodibility following a wildfire in eastern Spain
2010
This study examines the soil hydrological and erosional effects of ant mounds during summer and winter conditions following a wildfire in scrub terrain in eastern Spain. Forty rainfall simulations (1 m2 plots, 1 h duration, 78 mm h−1 intensity) were carried out over plots with mounds (n = 20) and mound-free control plots (n = 20) in August 2002, and repeated in December. By winter, some of the mound material had been removed and some vegetation regrowth occurred. Overall, mound presence increased soil erodibility in summer and winter due to the availability of highly erodible mound material. However, mound plots showed higher mean overland flow rates in summer (10·1 vs 6·9% for control plot…
Long-term non-sustainable soil erosion rates and soil compaction in drip-irrigated citrus plantation in Eastern Iberian Peninsula.
2021
Abstract Agriculture is known to commonly cause soil degradation. In the Mediterranean, soil erosion is widespread due to the millennia-old farming, and new drip-irrigated plantations on slopes, such as the citrus ones, accelerate the process of soil degradation. Until now, the published data about soil erosion in citrus orchards is based on short-term measurements. Long-term soil erosion measurements are needed to assess the sustainability of drip-irrigated citrus production and to design new strategies to control high soil erosion rates. The objective of this study is to assess long-term soil erosion rates in citrus plantations and report the changes in soil bulk density as indicators of …
Relationships between climate and soil hydrological and erosional characteristics along climatic gradients in Mediterranean limestone areas
1998
An investigation was undertaken to determine the relationships between climate and soil hydrological and erosional characteristics. Rainfall simulation experiments were carried out along three climatological gradients on similar limestone lithologies in the Mediterranean region. Standard experiments were used to characterize each site so that an objective comparison could be made. At each of the eleven south-facing slopes three experiments were carried out. A total of 33 plots were selected for the experiments; located in the Galilee and Carmel Mountains (Israel), Crete (Greece) and Alicante (Spain). Simulated rainfall was used in order to measure time to ponding and runoff, steady-state in…