Search results for "Soil surface"
showing 10 items of 28 documents
Evaluating roughness effects on C-band AMSR-E observations
2014
International audience; The usefulness of microwave remote sensing to retrieve near-surface soil moisture has already been demonstrated in many studies. However, obtaining high quality estimates of soil moisture is influenced by many effects from soil, vegetation and atmosphere; one of the key parameters is surface roughness. This research focusses on a semi-empirical method to evaluate the roughness effects from space borne observations. Global maps of roughness effects are evaluated at C-band from AMSR-E measurements.
Global-Scale Evaluation of Roughness Effects on C-Band AMSR-E Observations
2015
Quantifying roughness effects on ground surface emissivity is an important step in obtaining high-quality soil moisture products from large-scale passive microwave sensors. In this study, we used a semi-empirical method to evaluate roughness effects (parameterized here by the parameter) on a global scale from AMSR-E (Advanced Microwave Scanning Radiometer for EOS) observations. AMSR-E brightness temperatures at 6.9 GHz obtained from January 2009 to September 2011, together with estimations of soil moisture from the SMOS (Soil Moisture and Ocean Salinity) L3 products and of soil temperature from ECMWF’s (European Centre for Medium-range Weather Forecasting) were used as inputs in a retrieval…
Spatial variability of soil roughness in persimmon plantations: A new combined ISUM (improved stock unearthing method) approach
2019
Made available in DSpace on 2019-10-06T16:49:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-01 Universidade Estadual Paulista Soil roughness (SR) is an ecological indicator that describes the distribution of soil surface accumulations and ponds in a terrain, which allows understanding the connectivity of the flows as they act as sinks and sources of water and sediments. There is a set of methods that allows investigating the SR, and we test the use of the improved stock unearthing method (ISUM) as an easy-to-apply and low-cost approach. The ISUM has been initially tested in vineyards using the graft union and measures in the inter-row areas to assess the current soil surface l…
Eco-geomorphological connectivity and coupling interactions at hillslope scale in drylands: Concepts and critical examples
2020
The diagnosis of land degradation requires a deep understanding of ecosystem functioning and evolution. In dryland systems, in particular, research efforts must address the redistribution of scarce resources for vegetation, in a context of high spatial heterogeneity and non-linear response. This fact explains the prevalence of eco-hydrological perspectives interested in runoff processes and, the more recent, focused on connectivity as an indicator of system resource optimisation. From a geomorphological perspective and reviewing the concepts of eco-hydro-geomorphological interactions operating in ecosystems, this paper explores the effects of erosion on vegetation configuration through two …
Testing soil water repellency in a Sicilian area two years after a fire
2019
The water drop penetration time (WDPT) technique was applied in 2018 to check persistence of soil water repellency (SWR) in a Sicilian mountain area affected by a wildfire on June 2016. A total of four sites, that were severely water repellent immediately after burning, were sampled. Depending on the site, wettable soil conditions, less SWR and maintenance of a noticeable SWR were detected two years later. At the site showing a near-constant SWR, WDPTs were particularly high in the top soil layer (0-0.03 m) and they appreciably decreased more in depth. Signs of decreasing SWR in drier soil conditions and in association with coarser soil particles were also detected at this site. High gradie…
Biology of the preimaginal stages in trogid beetles (Coleoptera): Experimental data∗
1992
Abstract Some aspects of larval behaviour in two species of trogid beetles, Trox bispidus (Pontoppidan) from temperate Europe and Afromorgus tuberosus (Klug) from tropical Africa, have been studied experimentally. From the results obtained it emerges that the rise of the newborn larvae towards the soil surface is imputable to a simple negative geotropism. Larval food relocation also contributes to reducing aggressive interactions at the food source. The potential range of trophic and behavioural variation seems to be larger than that expressed in nature as a rule. This can contribute to explaining, in evolutive terms, the rare cases of transgression from a uniform trophic and behavioural pa…
Effect of cultivation techniques on the hydrodynamic and mechanical behaviour of the "Lauragais-terreforts"
1993
The effect of various seed bed preparations on hydrodynamic and mechanical parameters was studied experimentally by simulated rainfall on clayeyloamy soils Lauragais, which had developed on chalky molasse on a slope greater than 12 %. The level of soaked up rain ("pluie d'imbibition", Pi) is closely connected to the inital degree of saturation of the soil ; it varies from 10 to 24 mm when the soil is humid and increases when the soil is dry (14 to 47 mm). But when the soil surface is crusted the Pi is less and seems to be no longer controlled by the degree of water in the soil. Treatments with fine structural elements show the fewest possibilities of infiltration during the soaking up stage…
Using microtomography, image analysis and flow simulations to characterize soil surface seals
2012
Raindrops that impact on soil surface affect the pore structure and form compact soil surface seals. Damaged pore structure reduces water infiltration which can lead to increased soil erosion. We introduce here methods to characterize the properties of surface seals in a detailed manner. These methods include rainfall simulations, x-ray microtomography, image analysis and pore-scale flow simulations. Methods were tested using clay soil samples, and the results indicate that the sealing process changes several properties of the pore structure.
Proposal for a new diagnostic horizon for WRB Anthrosols
2009
Abstract To investigate man's role in the creation and evolution of soils in areas of large scale farming, and to investigate the main morpho-descriptive aspects of the related soils, a survey was carried out in south eastern Sicily, Italy, where, as common to other regions of the Mediterranean basin, there are wide areas with anthropogenic soils due to large scale farming activity. The complex genesis pattern of these anthropogenic soils, which shows a double sequence of man-made horizons, sideways oriented to the soil surface, does not allow their classification as Technosols, because their composition is not dominated or strongly influenced by artefacts or human-made materials as is the …
Quick and Slow Components of the Hydrologic Response at the Hillslope Scale
2016
It is widely recognized that the Hortonian mechanism of runoff generation occurs in arid and semi-arid regions, generally characterized by high rainfall intensity on soils exhibiting low infiltrabilities. Differently, in steeply sloping forested watersheds in humid climates, by infiltrating through a highly permeable upper soil horizon, water moves beneath the soil surface determining a slow response. However, in most real cases, for example when in arid regions mountain forested areas take place, both (quick and slow) runoff generation processes coexist and together contribute to the hydrologic hillslope response. In this paper, based on analytical solutions of the hydrologic response, ins…