Search results for "Water science"
showing 10 items of 1545 documents
Improvements in land surface temperature retrieval from the Landsat series thermal band using water vapor and air temperature
2009
[1] Land surface temperature (LST) is involved in many land surface processes such as evapotranspiration, net radiation, or air temperature modeling. In this paper we present an improved methodology to retrieve LST from Landsat 4 TM, Landsat 5 TM, and Landsat 7 ETM+ using four atmospheric databases covering different water vapor ranges (from 0 to 8 g cm−2) to build the LST retrieval models and using both water vapor and air temperature as input variables. We also compare this with LST retrievals using only water vapor or only air temperature, as well as with an existing LST retrieval algorithm. In order to validate the results, we have selected 77 Landsat images taken between 2002 and 2006 …
Simulation model comparing the hydroperiod of temporary ponds with different shapes
2010
A model of the water dynamics for shallow, small and temporary Mediterranean ponds has been developed taking into account the annual patterns of rainfall and potential evaporation, pond parameters (pond area, depth and shape) and watershed parameters (watershed area and saturated water content of the soil). This model predicts the amount of water retained in the pond in real time and therefore, when a pond is going to dry out. It is then possible to calculate how much water will remain in the pond after raining or the number of days per year that the pond is going to be dry. Analyses have been performed for different shapes of ponds and sensitivity of the state variables, at different value…
Mediterranean Coastal Lagoons Review: Sites to Visit before Disappearance
2022
Coastal lagoons are an established priority habitat in the European environment because of the biological communities that inhabit them. Their origin is related to the transport of sediments from a nearby river or the movement of sands by the marine currents that produce the closure of a gulf. Therefore, they are recent geological formations, which also disappear quickly if environmental conditions change. The 37 coastal lagoons with a surface area greater than 10 km2 located in the Mediterranean basin have been identified. Fishing has been the traditional use of these lagoons, in addition to their use as a navigation harbor when they are open to the sea. Pollution, quality problems and the…
Ceratium furcoides (Levander) Langhans in reservoirs at the Ebro watershed, Spain and Sao Paulo state, Brazil
2022
This study compares the morphological characteristics of the dinoflagellate Ceratium furcoides from three Ebro basin reser¬voirs (Spain) and from six reservoirs at São Paulo state (Brazil) with the aim to identify the distinct morphotypes of Ceratium furcoides in Spain and Brazil. We studied the physical and chemical variables to determine the trophic state of each reservoir. Unlike Ceratium hirundinella, Ceratium furcoides is not a frequent species within the plankton community at Ebro Basin reservoirs, however, this species has been responsible of one monospecific bloom at El Val reservoir. Nevertheless, both Ce-ratium species are considered invasive in South America. Ceratium furcoides h…
Mid-Holocene and historical palaeoecology of the Albufera de València coastal lagoon
2019
espanolLa laguna costera de la Albufera de Valencia es uno de los mayores lagos oligohalinos de la Peninsula Iberica. Fuertemente contaminada y amenazada por planeamientos de desarrollo urbanistico, fue finalmente protegida como Parque Natural en 1986, con el fin de preservar la cubeta y sus ambientes aledanos, los cuales consisten fundamentalmente en arrozales y un bosque sobre la barra arenosa costera. Los planes de restauracion se centran en recuperar la calidad del agua y la cobertura de macrofitos sumergidos que ocupaban la mayor parte de la laguna en los anos 50. Hasta la publicacion de algunos trabajos recientes, se conocia bien poco de la historia paleoambiental esta zona humeda. Co…
Sediment Transport and Hydrodynamic Parameters of Tsunami Waves Recorded in Onshore Geoarchives
2014
In regions with a short historical tsunami record, the assessment of long-term tsunami risk strongly depends on geological evidence of prehistoric events. Whereas dating tsunami deposits is already well established, magnitude assessment based on remaining sedimentary structures is still a major challenge. In this study, two approaches were applied to deduce transport processes and hydrodynamic parameters of tsunami events from onshore deposits found in the coastal plain of Ban Bang Sak, SW Thailand: (1) The maximum offshore sediment source was determined using granulometry, geochemistry, mineralogy and foraminifera of the tsunamites, and reference samples from various marine and terrestrial…
Diversity of meiofauna in the lacustrine profundal zone: Bathymetric differences and influence of environmental factors
1993
The diversity and species richness of total meiofauna, Harpacticoida and Oligochaeta in relation to depth and other environmental variables were studied at nine stations and in two profundal depth zones in Lake Paijanne which includes both oligotrophic and eutrophicated or organically loaded areas.
Spatio-temporal distribution and growth dynamics of phototrophic sulfur bacteria populations in the sulfide-rich Lake Arcas
2000
Lake Arcas exhibits a thermal stratification from April to October. A sulfide-rich anoxic hypolimnion is then formed between the deeper part of the thermocline and the lake bottom, and high population densities of phototrophic microorganisms are found at the oxic-anoxic interface. Chromatium weissei, a large rod, 8 × 4 μm in size, was the dominant phototrophic bacterium, reaching densities of up to 1.84 × 106 cells ml-1. Other phototrophic sulfur bacteria, such as Amoebobacter cf. purpureus, Thiocapsa sp., and Pelodictyon clathratiforme were also present in the anoxic hypolimnion, but their cell size and population densities were much lower. Net growth rates (0.125 to —0.123 d-1) and freque…
Tariffs and efficient performance by water suppliers: an empirical approach
2012
Water leaks are an environmental and sustainable issue as well as an economic issue. The objective of this paper is to analyse the efficiency of a sample of Spanish urban water systems by considering water leaks in a network as undesirable outputs. Data envelopment analysis (DEA), an analytical benchmarking methodology, is used to calculate technical and economic efficiency. We also discuss the possible relationship between efficiency and tariffs charged to users. Results show that the possibilities for reducing water leaks in networks are high, thus demonstrating that there is room for savings from an economic and environmental point of view. The assessment of efficiency performance could …
From industrial consensus to environmental regulation: the coming of the Finnish industrial waste-water policy
1998
Abstract The development of the Finnish industrial waste-water policy is examined in the context of the national industrial development and the rise of the environmental movement. It is stated that up until the beginning of the eighties, a broad consensus about the principles of the waste-water policy prevailed among decision makers and authorities. It was a consensus uniform with the interests of the forest industry, the most powerful part of the national economy. Unfortunately, the forest industry was a bad source of pollution of the inland waters since the fifties. However, the long lasted hegemonic consensus started to break down in the late seventies and early eighties by an awakening …