Search results for "surface water"
showing 10 items of 106 documents
High resolution remote estimation of soil surface water content by a thermal inertia approach
2009
Summary The spatial distribution of soil surface water content in a bare soil was evaluated by a thermal inertia approach from high resolution visible/near infrared (VIS/NIR) and thermal infrared (TIR) airborne data. Given that the relationship between the thermal inertia and the soil water content strongly depends on the accurate estimation of the soil thermal conductivity, two different empirical models were applied to estimate it. Remotely estimated water contents were tested with time domain reflectometry (TDR) measurements collected on a 110 × 90 m 2 bare field in coincidence with airborne over-flights. The thermal conductivity model by Johansen (1975) produced more accurate estimates …
An insight into water stable isotope signatures in temperate catchment
2020
Abstract Stable isotopes are used to decipher hydrological processes in watershed research. A two-year monthly monitoring of hydrogen and oxygen stable isotope ratios (δ2H and δ18O) in a temperate catchment in Norther Europa, Latvia was undertaken. Isotope ratios in common water types – raised bog, confined groundwater, unconfined groundwater and surface water – were measured. We found characteristic signatures of isotope ratios for each of these four water types. The average isotope ratios of different water types ranged from −80.8 to −68.3‰ for δ2H and −11.46 to −8.76‰ for δ18O, with standard deviations from 18 to 25‰ and 0.10 to 1.59‰, respectively. The isotope ratios of the stream base …
Estimation of the water table depth of the Calarasi district Island (Romania) at the Danube River using ASTER/DEM data
2014
The water table is the top level of ground water by definition. Therefore surface water is an exposed part of the water table. Airborne measurements, resistivimeters determinations or perforation analyses can be used to determine the water table depth. These methods require, approximately, taking a sample per hectare, which is a very expensive and time-consuming procedure. However, remote sensing constitutes an ideal alternative to determine water table depth, because unlike the existing methodologies, which are very expensive due to equipment and travel expenses, the proposed methodology is cheap and simple. The ASTER GDEM data is available at no charge to users via electronic download and…
Effect of climate on surface flow along a climatological gradient in Israel: a field rainfall simulation approach
1998
Abstract A climatological gradient was selected in Israel to examine the effects of climate on surface flow and soil erosion. The gradient is composed of eight study areas located between the Dead Sea and the Galilee Mountains. Mean annual rainfall ranges from 100 mm year −1 in the driest site to 900 mm year −1 in the wettest site. Simulated rainfall experiments were performed in order to determine the main hydrological and erosional parameters. Data were recorded in 36 different plots after showers of 50 mm h −1 rain intensity and 45–60 min duration. In the arid sites ( −1 ) abundant runoff appeared on the soil surface very quickly, and the infiltration rates were very low. Erosion rates, …
Effect of plant species on water balance in a pilot-scale horizontal subsurface flow constructed wetland planted with Arundo donax L. and Cyperus alt…
2015
Abstract In constructed wetland systems (CWs) for wastewater treatment, evapotranspiration (ET) is the most important water balance component in arid and semi-arid regions, where high performance levels are needed when treating contaminants and where it is also vital to preserve as much water as possible for reuse in irrigation. This study shows the results of a series of water balance measurements obtained between 2012 and 2013 from a pilot HSSF system in the West of Sicily (Italy). The system was made by two separate vegetated units: one with Arundo donax L. (giant reed) and the other with Cyperus alternifolius L. (umbrella sedge), and fed with urban wastewater following secondary treatme…
Comparison of the behaviour of three herbicides in a field experiment under bare soil conditions
2006
Abstract A case-study was design in order to rank three alternative herbicides according to their exposure to surface waters. Herbicide persistence and losses to surface waters were studied in an uncultivated Finnish field (ca. 3500 m2, slope
Hydrochemical evolution and environmental features of Salso River catchment, central Sicily (Italy)
2000
A hydrogeochemical study of the Salso River highlighted the chemical and isotopic space-time evolution along its flow path and the main contamination processes. Within the basin, three different hydrogeochemical facies have been individuated: (1) Ca-Mg-HCO3, (2) Ca-Mg-SO4 and (3) Na-Cl. The first facies reflects the chemical composition of the groundwaters hosted in the carbonate reliefs that belong to the Madonie Mountains. The second and the third facies are the result of the interaction processes between surface waters and the gypsum and salty clays, respectively. Two pollution sources have been also located in the basin downstream from the salt mine and downstream from a discharge area …
Water budgets of three small catchments under montane forest in Ecuador: experimental and modelling approach
2006
The water budget of forested catchments controls the local water supply and influences the regional climate. To assess the anthropogenic impact on the water cycle, we constructed a water budget for three ∼10 ha catchments under lower montane forest on the east-facing slope of the Andes in south Ecuador at 1900–2150 m elevation. We used field hydrological measurements and modelled surface flows with TOPMODEL, a semi-distributed catchment model. We measured incident precipitation, throughfall, stemflow, and surface flow between May 1998 and April 2002 in hourly to weekly resolution, and determined all variables needed to parameterise TOPMODEL. On average, of the four monitored years and three…
Long-term changes in hydrological regime of the lakes in Latvia
2013
Changes in the hydrological regime of the lakes of Latvia depend on natural and anthropogenic causes. This publication summarises the results of the research on the long-term changes in the water level, thermal and ice regimes in the seven largest lakes of Latvia: Liepājas, Usma, Ķīšezers, Burtnieks, Rāzna, Sventes and Lielais Ludzas, and their regional specifics from 1926 to 2002. For most of the studied lakes, the water level has been regulated, except for the lakes Liepājas, Burtnieks and Ķīšezers. Global climate warming has caused considerable changes in the hydrological regime of the lakes during the last decades and the surface water temperature has increased. At the same time, the nu…
Hydrogeochemistry and Water Balance in the Coastal Wetland Area of “Biviere di Gela,” Sicily, Italy
2006
In the study area physical and chemical factors control the composition of surface and groundwaters, which in turn determine the water quality of the "Biviere di Gela" lake. These factors combine to create diverse water types which change their compositional character spatially as rainfall infiltrates the soil zone, moves down a topographically defined flow path, and interacts with bedrock minerals. Low-salinity waters, which represent the initial stage of underground circulation, start dissolving calcium carbonate from the local rocks. The progressive increase in salinity, characterized by substantially higher Ca, SO4, Na and Cl concentrations, suggests that dissolution of CaSO4 and NaCl i…