Search results for "soil"

ON THE USE OF SATELLITE THERMAL DATA FOR DETERMINING EVAPOTRANSPIRATION IN PARTIALLY VEGETATED AREAS

1992

Abstract The use of satellite data for determining daily evapotranspiration over completely vegetated areas has been analysed by different authors. However, if the soil surface is partially covered by vegetation the problem becomes more complicated, because in this case the value of the temperature measured by the satellite varies with the viewing geometry. In this work we have studied the influence of the satellite observation angle for crops with different cover degree, field geometry and ground emissivity. For this purpose we have used the simplified relation proposed by Jackson et al.LET d=Rnd−B(T3−T a)iwhere ET 4 and R nd are the daily values of evapotranspiration and net radiation res…

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, …

Biohydrology: coupling biology and soil hydrology from pores to landscapes

2010

The articles in this issue are a selection of the presentations made at the 2nd International Conference of Biohydrology. This special issue ‘Biohydrology—coupling biology and soil hydrology from pores to landscapes’ contains a range of articles on biological and hydrological interactions in soil, including large-scale systems research on the influence of forests on catchments and small-scale reductionist research on processes operating at the scale of soil pores. Copyright  2010 John Wiley & Sons, Ltd.

Ecohydrological adaptation of soils following land abandonment in a semi-arid environment

2010

Representative land use types were selected in southeast Spain to investigate the redistribution of soil water in relation to vegetation development and land abandonment.Simulated rainfall experiments were performed during 2 days on each of the four selected surfaces: ploughed, a 3-year fallow field, a 12-year abandoned field with shrubs and a semi-natural field with Stipa tenacissima tussocks. Each experiment consisted of five runs of artificial rain. Soil moisture dynamics were measured by time domain reflectometry (TDR), as well as runoff and ponding on the plot surface. Also the movement of the wetting front was measured after each run.On the ploughed field, ponding and local runoff wer…

Effects of soil gas permeability and recirculation flux on soil CO2 flux measurements performed using a closed dynamic accumulation chamber

2009

Abstract Dynamic accumulation chamber methods have been extensively used to estimate the total output of CO2 released from active volcanic area. In order to asses the performance and reliability of a closed dynamic system several tests were carried out with different soil permeabilities and soil CO2 fluxes. A special device was used to create a constant one-dimensional CO2 flux through a soil column with a known permeability. Three permeabilities were investigated, ranging between 3.6 × 10− 2 and 3.5 × 10 μm2, as were several CO2 fluxes (ranging between 1.1 × 10− 6 and 6.3 × 10− 5 kg m− 2 s− 1). The results highlight that the accuracy of soil CO2 flux measurements strictly depends on the so…

Predicting event soil loss from bare plots at two Italian sites

2013

Abstract Including runoff in USLE-type empirical models is expected to improve plot soil loss prediction at the event temporal scale and literature yields encouraging signs of the possibility to simply estimate runoff at these spatial and temporal scales. The objective of this paper was to develop an estimating procedure of event soil loss from bare plots (length = 11–44 m, slope steepness = 14.9–16.0%) at two Italian sites, i.e. Masse, in Umbria, and Sparacia, in Sicily, having a similar sand content (5–7%) but different silt (33% at Sparacia, 59% at Masse) and clay (62% and 34%, respectively) contents. A test of alternative erosivity indices for the Masse station showed that the best perf…

Critical analysis of empirical ground heat flux equations on a cereal field using micrometeorological data

2009

The rate at which the net radiation is transferred to the soil as ground heat flux varies with surface characteristics. Surface energy balance algorithms use empirical relationships taking into account the effects of the canopy cover to insulate the soil through vegetation indexes, the soil capacity to absorb incoming net radiation via the albedo, and the surface temperature promoting the energy transfer. However empirical relationships are often dependent on local conditions, such as the soil humidity and vegetation type. Ground heat flux assumes a minimum value in case of full canopy cover and a maximum value for dry bare soil. Aim of the present research is the critical analysis of some …

Assessing crop coefficients of sunflower and canola using two-source energy balance and thermal radiometry

2014

Abstract A new technique for the local adjustments in crop coefficients is presented. This is an alternative to conventional lysimeter measurements traditionally used for improved irrigation scheduling. The method is based on the combination of a two-source energy balance model and local measurements of radiometric temperatures. Two experimental campaigns were carried out on sunflower and canola in a cropland area located in Barrax, Albacete, in the summer of 2011 and spring of 2012, respectively. Radiometric temperatures of soil and canopy were collected, together with biophysical and meteorological variables. Combining all these data in a two-source energy balance model allowed separation…

2019

Flooding may damage important transportation infrastructures, such as roads, railways and bridges, which need to be well planned and designed to be able to withstand current and possible future climate-driven increases in flood frequencies and magnitudes. This study develops a novel approach to predictive statistical modelling of the probability of flooding at major road-stream intersection sites, where water, sediment and debris can accumulate and cause failure of drainage facilities and associated road damages. Two areas in south-west Sweden, affected by severe floods in August 2014, are used in representative case studies for this development. A set of physical catchment-descriptors (PCD…

The use of Easy-Barriers to control soil and water losses in fire-affected land in Quesada, Andalusia, Spain

2019

Abstract Soil erosion is enhanced by wildfire, mainly due to the loss of vegetation cover and changes in soil properties. After wildfires, there is a need to control the non-sustainable soil and water losses. Of the strategies commonly applied, the use of contour felled log debris barriers to sediment trapping is widespread, but this is not always successful in Mediterranean Ecosystems. This paper evaluates the effectiveness of a new barrier which can be applied on steep terrains affected by wildfires. The hydrological response and sediment delivery were measured to test a innovative design, which are easy to transport and use. The Easy-Barriers (EB) size is 0.8 × 0.1 × 0.2 m and were desig…