1,721,266 research outputs found
Preferential flow in macroporous swelling soil with internal catchment: model development and applications
No full textA new model of infiltration in swelling and shrinking clay soil was developed. The model consisted of two flow domains: soil matrix, with flow modelled by means of Darcy equation, and macropores; the latter was divided in turn into two sub-domains: shrinkage cracks, with aperture dynamically depending on matrix water content, and permanent macropores, independent of matrix saturation. In the shrinkage cracks sub-domain, a kinematic wave equation was derived by considering laminar motion of thin water films, along two parallel nearly vertical walls; in the permanent macropores sub-domain, a kinematic wave equation was assumed, with parameters physically related with macropores shape and dimension. Exchange of water between macropore domains and matrix was introduced in form of sink terms in the macropores mass balance equations, and as source terms in the matrix continuity equation. Infiltration through macropore walls was modelled using a diffusivity function derived from aggregates sorptivity measurements. The internal catchment was included by considering at each layer a fraction of dead end permanent macropores. Water ponding at the bottom of dead end macropores, infiltrated into the corresponding matrix layer. The model was tested against the results of infiltration transients through a large undisturbed swelling and shrinking clay soil column. Outflow rate from column bottom surface was constantly measured, while water content profile was registered at regular time intervals by means of five TDR horizontal probes. In order to quantify model parameters, characterisation of soil matrix was carried out, providing hydraulic conductivity curve, water retention curve, shrinkage characteristic and aggregates diffusivity. All of the other model parameters, thanks to their clear physical meaning, were estimated from direct observation of soil structure, except macropores morphologic parameters, some of which, although measurable, were obtained by calibration due to lack of relevant experimental data. The proposed model proved to be able to adequately simulate measured breakthrough curves as well as temporal evolution of water content profiles along the sample, especially with internal catchment process included
TDR water content inverse profiling in pyroclastic soils for early warning of fast landslides triggering
No full text
Soil water content inverse profiling from single TDR waveforms
No full textAn inverse procedure for the estimation of soil water content profiles along TDR probes is presented. A TDR metallic probe is considered as a transmission line, for which relevant partial derivatives equations apply. The direct problem consists in the integration of transmission line equations, providing V(x,t) along the line. To this aim, the unit length parameters of the transmission line must be known. In particular, unit .....
A fuzzy-autoregressive model of daily river flows
No full textA model for the identification of daily river flows has been developed, consisting of the combination of an autoregressive model with a fuzzy inference system. The AR model is devoted to the identification of base flow, supposed to be described by linear laws. The fuzzy model identifies the surface runoff, by applying a small set of linguistic statements, deriving from the knowledge of the physical features of the nonlinear rainfall-runoff transformation, to the inflow entering the river basin. The model has been applied to the identification of the daily flow series of river Volturno at Cancello-Arnone (Southern Italy), with a drainage basin of around 5560km 2, observed between 1970 and 1974. The inflow was estimated on the basis of daily precipitations registered during the same years at six rain gauges located throughout the basin. The first two years were used for model training, the remaining three for the validation. The obtained results show that the proposed model provides good predictions of either low river flows or high floods, although the analysis of residuals, which do not turn out to be a white noise, indicates that the cause and effect relationship between rainfall and runoff is not completely identified by the mode
Misura di profili di contenuto d’acqua del terreno con la riflettometria nel dominio del tempo
No full textMonitoraggio di processi di infiltrazione ed evaporazione con la riflettometria nel dominio del tempo
No full textCommento al Capo I ‘Obiettivo di qualità ambientale e obiettivo di qualità per specifica destinazione’, Titolo II ‘Obiettivi di qualità’ della Sezione II ‘Tutela delle acque dall’inquinamento’ della parte 3a ‘Norme in materia di difesa del suolo e lotta alla desertificazione, di tutela delle acque dall’inquinamento e di gestione delle risorse idriche’ (articoli dal 77 al 78-octies) del d.lgs. 152 del 2006
No full text- …
