CRS4 Libro, Contributo in un libro
URI permanente per questa collection
Sfogliare
submissions recenti
- Item3D spectral reverse time migration with no-wraparound absorbing conditions(SEG, 1998) Bonomi, Ernesto; Brieger, Leesa; Nardone, Carlo; Pieroni, EnricoComparative studies of methods of reverse time migration (RTM) show that spectral methods for calculating the Laplacian impose the least stringent demands on discretization stepsize; thus with spectral methods, the grid refinements often required by other methods can be avoided. Implemented with absorbing boundary conditions, which are energy-tuned to give good absorption at the boundaries, these spectral methods can be used effectively for migration, without suffering the problems of wraparound which have traditionally plagued them (Furumyra and Takenaka, 1995).
- ItemCoupled surface runoff and subsurface flow model for catchment simulations(Wageningen Press, 1999) Bixio, Anna Chiara; Orlandini, Stefano; Paniconi, Claudio; Putti, MarioA distributed catchment scale numerical model for the simulation of coupled surface runoff and subsurface flow is presented. Starting from rainfall (evaporation) records, the model first determines the infiltration (exfiltration) rates in the soil, by evaluation of the soil field capacity at the specific conditions as calculated from the three-dimensional solution of the variably-saturated groundwater flow model (Richards’ equation). The flow rate that remains or returns to the surface, the so called overland flow, is then routed via a diffusion wave surface runoff model based on a Muskingum-Cunge scheme with variable parameters. Both hillslope and channel flow are described, and a special algorithm is used for the simulation of pools/lakes effects on storm-flow response. The importance of including detailed subsurface flow description in catchment simulations is shown on a simple testcase characterized by the presence of a central depression.
- ItemGuidelines for validation and verification of groundwater mathematical studies (GULLIVER): a case study(WIT, 2000) Troisi, S.; Straface, S.; Gambolati, Giuseppe; Putti, Mario; Paniconi, ClaudioThe goal of this work is to define a set of guidelines for “validating" mathematical models that are to be used in real-world problems of subsurface flow and contaminant transport. Groundwater models today are being used to study increasingly complex problems involving large temporal and spatial scales and with many uncertainties inherent in the data and in the models themselves. It becomes important therefore to establish procedures and benchmark tests with which to assess a given model's adequacy for simulating a specific groundwater problem. In the GULLIVER project we propose to create a public library of phenomenological schemes (PS), each one satisfactorily solved by an established model. A user with a specific application and model at hand can select the PS that most closely corresponds to his application, and corroborate his model against the established solution. The user's model is considered validated when the two numerical solutions match according to specified criteria. In this paper we describe this methodology and present its application to a 2D saturated flow and transport test case based on data from a field study site in Calabria, Italy.
- ItemSoil moisture mapping from ASAR imagery for the Flumendosa and Meuse river basins(2000) Paniconi, Claudio; Troch, P. A.; Mancini, M.; Dessena, M. A.Soil moisture monitoring and the characterization of the spatial and temporal variability of this hydrologic parameter at scales from small catchments to large river basins continues to receive much attention, reflecting its critical role in subsurface – land surface – atmosphere interactions and its importance to drought analysis, crop yield forecasting, irrigation planning, flood protection, and forest fire prevention. We will describe the objectives and methodologies of an Envisat project that will aim to produce maps of seasonal soil moisture patterns at the regional scale based on ASAR imagery. The work will be carried out for two river basins that have significantly different climatic, geologic, and land use characteristics: the Flumendosa basin in Sardinia (Italy) and the larger Meuse basin that drains a good part of Belgium and the Netherlands as well as portions of France, Germany, and Luxembourg. High resolution ASAR data will be acquired over selected catchment scale test sites within each of these study regions, whereas medium resolution images will be acquired over the entire river basin (or extended region in the case of the smaller basin). A statistical analysis of the information from the processed images at these two different scales will be used to develop an aggregation methodology to generate large scale soil moisture maps. Data assimilation techniques will also be developed for dynamically integrating the high resolution satellite data into catchment scale hydrological simulation models. The work being planned will be placed in the context of recent efforts at validating and applying SAR soil moisture data, which we will briefly review.
- ItemAnalysis of seawater intrusion phenomena in the Korba coastal aquifer of Tunisia(Taylor & Francis, 2000) Paniconi, Claudio; Giacomelli, Andrea; Lecca, Giuditta; Khlaifi, Ihsen; Tarhouni, JamilaA geographic information system and a three-dimensional coupled variable density and saturation numerical model are implemented for the Korba coastal aquifer of northeastern Tunisia, and preliminary simulations are performed to investigate seawater intrusion phenomena. The GIS provides an essential platform for data management, enabling the organization and merging of a large volume of data that has been collected in often ad hoc manner from diverse sources over many years. A critical assessment of data quality is provided and the usefulness of GIS and modeling tools is demonstrated, with an aim to encourage more directed and continuous monitoring and characterization of important parameters and processes involved in the contamination phenomena. This approach is currently being extended to two other coastal aquifers, in Sardinia (Italy) and Sahel (Morocco).