1,721,010 research outputs found
FLOW PATTERNS WITHIN A SLOPING PERCHED WATER IN A GRADUALLY LAYERED SOIL
No full textThe onset of a perched water table in a sloping soil, during
rainfall events, is one of the most important landslides
triggering mechanisms. As perched water tables are mostly
induced by the decreasing of the hydraulic conductivity at
soil saturation with depth, in this paper we will present
some results on the effect of gradually decreasing
conductivity on the flow due to a steady infiltration process
in a sloping and a priori anisotropic soil, laying on a
capillary barrier. On the basis of an application of the Darcy
law, the flow field within the perched water is analytically
solved and the corresponding Lagrange stream function is
determined. The flow patterns are calculated and presented
for the particular case of exponentially decreasing hydraulic
conductivity at saturation with depth
The Impact of Meteorological Drought on Vegetation Health in the Middle Euphrates River Basin (Syria)
Full text linkSyria is now witnessing the dramatic effects of a multiyear drought that has been afflicting the
country since 2006. The drought has impacted several regions, but the north-eastern Al Jazira
region, corresponding to the Middle Euphrates River basin and considered the Syrian
“breadbasket”, has been hammered particularly severely
GIS—based application of Benfratello's method to estimate the irrigation deficit and its uncertainty under different climate change scenarios
No full textLand cover changes since the 19th century detected from historic maps for environmental applications: toward a “CORINE 1800” project?
Full text linkThe value of cartographic heritage for environmental applications is demonstrated with a test case in the Cen-tral Italian Alps. Land cover changes since the early 19th century are detected from sample maps in Lombardy of the Second Military survey of the Habsburg Empire (1816-1821), available on the portal mapire.eu. They are compared with 1954 aerial surveys and successive land use classification until 2018. Issues as land useclasses homogenization, data vectorization, georeferencing errors are addressed. The dynamics of four main land-use classes (woods, meadows, crops and urbanized areas) are investigated and the potential use of this exercise for hydrological applications is explored. The impact of the observed natural afforestation on changes of hydrological losses due to evapotranspiration and its influence as a likely cause of the decrease of runoff monitored since 1845 in the Adda river basin are assessed. The proposed test case can pave the road of a project extended at European scale, a sort of “CORINE 1800 land use” Geographic Information System which can have several environmental, cartographic and socio-economic applications
Back-analysis of an artificially triggered landslide: A case study in Northern Italy
No full textThe paper presents a case study of a landslide event, artificially triggered by an exceptional
infiltration in an otherwise stable slope. The work aims at investigating the slope failure
mechanism within a simplified two-dimensional conceptual framework based on the
formation of a perched water table. The landslide occurred in Northern Italy in April 2010,
on a hillside with average slope angle 36°–37°; the event affected an area of about 200 m2,
the slip surface was located approximately 1 m below the slope profile, in the uppermost
layers of a predominantly coarse, well graded soil. A series of numerical simulations were
performed to back-analyze the event, using a commercial computer program. The artificial
water infiltration and water content evolution were simulated with a two-dimensional finite
element (FE) model of the unsaturated-saturated domain with appropriate infiltration
boundary conditions. The slope stability analyses were conducted with classic limit
equilibrium (LE) methods and were performed at different time instants during the
infiltration process. The soil-water retention curves and conductivity functions were defined
according to the van Genuchten-Mualem model, with parameters estimated by means of the
software Rosetta (United States Department of Agriculture). The combined FE and LE
simulations showed the gradual formation of a perched water table, whose associated
localized pore pressure distribution results in the loss of the suction stabilizing effect and
thus in the reduction of the safety factor. Although supported by basic soil mechanical and
hydraulic characterization, the numerical simulations allowed to perform a back-analysis
which effectively captured the timing of the event, the location and depth of the slip surface
along the slope
Analysis and survey of Lake Garda lemon houses: a tool to understand and manage a Mediterranean landscape in Lombardy
No full textLake Garda mild microclimate allowed the settlement and flourishing of a peculiar cultivation, that of the limonaie (lemon houses), which, at the time of its splendour, during the Little Ice Age, was the Northernmost citrus cultivation in whole earth and exported citrus in Central and Northern Europe. In a contribution to the 8th edition of the Symposium we highlighted the Mediterranean character of the landscape of the lemon houses. Here we enlighten how, in order to preserve this unique cultural heritage, there is an urgent need of a census accounting for both the current condition of the ancient productive sites and for all the agroecosystemic relationships between the limonaie, which contributed to shape their landscape. Due to the great water requirement of the citrus cultivations at mid latitudes, a particular attention is devoted to the traditional water harvesting and irrigation structures
Solutes dynamics in the surface layer of anthropized soils in the province of Brescia (Italy)
No full textA method to assess the uncertainty of Benfratello's estimate of the irrigation deficit in a semiarid area and its GIS based application for anthropogenic and climate change scenarios
No full textModelling of an accidentally triggered shallow landslide in Northern Italy
Full text linkThe paper presents a case study of a landslide event, accidentally triggered by an unexpected and extraordinary infiltration in an otherwise stable slope. The work aims at modelling the slope failure mechanism with a simplified two-dimensional framework based on the formation of a perched water table. The landslide occurred in Val Venosta/Vinschgau Valley, in Northern Italy, in April 2010 and produced catastrophic consequences. It took place on a hillside with average slope angle 36° and affected an area of about 200 m2; the slip surface was located approximately 1.0 m below the slope profile, in the uppermost layers of a predominantly coarse, well-graded soil. A series of numerical simulations were performed to back-analyse the event, using a commercial computer program. The artificial water infiltration and water content evolution were modelled with a two-dimensional finite element model (FE) of the unsaturated/saturated domain with appropriate infiltration boundary conditions. The slope stability analyses were conducted with a classic limit equilibrium method (LE) and were performed at different time instants during the infiltration process. The soil-water retention curves and conductivity functions were defined according to the van Genuchten-Mualem model. The combined FE and LE simulations showed the gradual formation of a perched water table, whose associated localized pore pressure distribution resulted in the loss of the suction stabilizing effect and thus in the reduction of the safety factor. Although supported by basic soil mechanical and hydraulic characterization, the numerical simulations allowed to perform a back-analysis which effectively captured the timing of the event and the location and depth of the slip surface along the slope
A GIS based application of Benfratello's method to estimate the irrigation deficit in a semiarid climate
No full text- …
