Littérature scientifique sur le sujet « Geostatistical procedure »

Abstract: The main objective of this study is to estimate variables related to transportation planning, in particular transit trip production, by proposing a geostatistical procedure. The procedure combines the semivariogram deconvolution and Kriging with External Drift (KED). The method consists of initially assuming a disaggregated systematic sample from aggregate data. Subsequently, KED was applied to estimate the primary variable, considering the population as a secondary input. This research assesses two types of information related to the city of Salvador (Bahia, Brazil): an origin-destination dataset based on a home-interview survey carried out in 1995 and the 2010 census data. Besides standing out for the application of Geostatistics in the field of transportation planning, this paper introduces the concepts of semivariogram deconvolution applied to aggregated travel data. Thus far these aspects have not been explored in the research area. In this way, this paper mainly presents three contributions: 1) estimating urban travel data in unsampled spatial locations; 2) obtaining the values of the variable of interest deriving out of other variables; and 3) introducing a simple semivariogram deconvolution procedure, considering that disaggregated data are not available to maintain the confidentiality of individual data.

Abstract. This study presents a stochastic, three-dimensional characterization of a heterogeneous hydraulic conductivity field within DOE's Hanford 300 Area site, Washington, by assimilating large-scale, constant-rate injection test data with small-scale, three-dimensional electromagnetic borehole flowmeter (EBF) measurement data. We first inverted the injection test data to estimate the transmissivity field, using zeroth-order temporal moments of pressure buildup curves. We applied a newly developed Bayesian geostatistical inversion framework, the method of anchored distributions (MAD), to obtain a joint posterior distribution of geostatistical parameters and local log-transmissivities at multiple locations. The unique aspects of MAD that make it suitable for this purpose are its ability to integrate multi-scale, multi-type data within a Bayesian framework and to compute a nonparametric posterior distribution. After we combined the distribution of transmissivities with depth-discrete relative-conductivity profile from the EBF data, we inferred the three-dimensional geostatistical parameters of the log-conductivity field, using the Bayesian model-based geostatistics. Such consistent use of the Bayesian approach throughout the procedure enabled us to systematically incorporate data uncertainty into the final posterior distribution. The method was tested in a synthetic study and validated using the actual data that was not part of the estimation. Results showed broader and skewed posterior distributions of geostatistical parameters except for the mean, which suggests the importance of inferring the entire distribution to quantify the parameter uncertainty.

Abstract. This study presents a stochastic, three-dimensional characterization of a heterogeneous hydraulic conductivity field within the Hanford 300 Area, Washington, USA, by assimilating large-scale, constant-rate injection test data with small-scale, three-dimensional electromagnetic borehole flowmeter (EBF) measurement data. We first inverted the injection test data to estimate the transmissivity field, using zeroth-order temporal moments of pressure buildup curves. We applied a newly developed Bayesian geostatistical inversion framework, the method of anchored distributions (MAD), to obtain a joint posterior distribution of geostatistical parameters and local log-transmissivities at multiple locations. The unique aspects of MAD that make it suitable for this purpose are its ability to integrate multi-scale, multi-type data within a Bayesian framework and to compute a nonparametric posterior distribution. After we combined the distribution of transmissivities with depth-discrete relative-conductivity profile from the EBF data, we inferred the three-dimensional geostatistical parameters of the log-conductivity field, using the Bayesian model-based geostatistics. Such consistent use of the Bayesian approach throughout the procedure enabled us to systematically incorporate data uncertainty into the final posterior distribution. The method was tested in a synthetic study and validated using the actual data that was not part of the estimation. Results showed broader and skewed posterior distributions of geostatistical parameters except for the mean, which suggests the importance of inferring the entire distribution to quantify the parameter uncertainty.

Abstract. Limitations of cluster analysis as a procedure for classifying parameters of rainfall-runoff models are discussed, and a procedure is suggested by which such parameters could be estimated, using site characteristics together with a split record test as a measure of performance. It is suggested that geostatistical models may be a possible alternative to procedures based on cluster analysis, and that long-established principles of experimental design (replication, randomization) be used for comparing alternative PUB procedures.

Abstract. Our study develops and tests a geostatistical technique for locally enhancing macro-scale rainfall–runoff simulations on the basis of observed streamflow data that were not used in calibration. We consider Tyrol (Austria and Italy) and two different types of daily streamflow data: macro-scale rainfall–runoff simulations at 11 prediction nodes and observations at 46 gauged catchments. The technique consists of three main steps: (1) period-of-record flow–duration curves (FDCs) are geostatistically predicted at target ungauged basins, for which macro-scale model runs are available; (2) residuals between geostatistically predicted FDCs and FDCs constructed from simulated streamflow series are computed; (3) the relationship between duration and residuals is used for enhancing simulated time series at target basins. We apply the technique in cross-validation to 11 gauged catchments, for which simulated and observed streamflow series are available over the period 1980–2010. Our results show that (1) the procedure can significantly enhance macro-scale simulations (regional LNSE increases from nearly zero to ≈0.7) and (2) improvements are significant for low gauging network densities (i.e. 1 gauge per 2000 km2).

The importance of surface roughness and its non-destructive examination has often been emphasised in structural rehabilitation. The presented innovative procedure enables the estimation of concrete-to-concrete strength based on a combination of low-cost, area-limited tests and geostatistical methods. The new method removes the shortcomings of the existing one, i.e., it is neither qualitative nor subjective. The interface strength factors, cohesion and friction, can be estimated accurately based on the collected data on a surface texture. The data acquisition needed to create digital models of the concrete surface can be performed by terrestrial close-range photogrammetry or other methods. In the presented procedure, limitations to the availability of concrete surfaces are overcome by the generation of subsequential Gaussian random fields (via height profiles) based on the semivariograms fitted to the digital surface models. In this way, the randomness of the surface texture is reproduced. The selected roughness parameters, such as mean valley depth and, most importantly, the geostatistical semivariogram parameter sill, were transformed into contact bond strength parameters based on the available strength tests. The proposed procedure estimates the interface bond strength based on the geostatistical methods applied to the numerical surface model and can be used in practical and theoretical applications.

Abstract. This study compares the performance of two geostatistical approaches, parametric and non-parametric, to evaluate the spatial distribution of water retention curves. Data used in this study were obtained from the Las Cruces trench site database that contains water retention data for 448 soil samples. In a commonly used parametric approach, three standard water retention models, i.e. Brooks and Corey (BC), van Genuchten (VG), and log-normal (LN), were first fitted to each data set. For each model, a cross validation procedure was used to estimate parameters at each sampling location, allowing computation of prediction errors. In a rarely used non-parametric approach, a cross validation procedure was first used to directly estimate water content values for eleven pressure heads at each sampling location and then the three water retention models were fitted using the same automated procedure to compute prediction errors. The results show that the non-parametric approach significantly lowered prediction errors for the VG model, while moderately reducing them also for the LN and BC models.

Summary The stochastic inversion of spatial distribution of lithofacies from multiphase production data is a difficult problem. This is true even for the simplest case, addressed here, of a sand/shale distribution and under the assumption that reservoir properties are constant within each lithofacies. Two geostatistically based inverse techniques, sequential self-calibration (SSC) and GeoMorphing (GM), are extended for such purposes and then compared with synthetic reference fields. The extension of both techniques is based on the one-to-one relationship existing between lithofacies and Gaussian deviates in truncated Gaussian simulation. Both techniques attempt to modify the field of Gaussian deviates while maintaining the truncation threshold field through an optimization procedure. Maintaining a fixed threshold field, which has been computed previously on the basis of prior lithofacies proportion data, well data, and other static soft data, guarantees preservation of the initial geostatistical structure. Comparisons of the two techniques using 2D and 3D synthetic data show that the SSC is very efficient in producing sand/shale realizations matching production data and reproducing the large-scale patterns displayed in the reference fields, although it has difficulty in reproducing small-scale features. GM is a simpler algorithm than SSC, but it is computationally more intensive and has difficulty in matching complex production data. Better results could be obtained with a combination of the two techniques in which SSC is used to generate realizations identifying large-scale features; then, these realizations could be used as input to GM for a final update to match small-scale details. Introduction Reliable predictions of future reservoir performance require reservoir models that incorporate all available relevant information. Geostatistical methods are widely used and well suited to construct reservoir models of porosity and permeability honoring static data, such as core data, well-log data, seismic data, and geological conceptual data. Dynamic production data, such as production rate, pressure, water cut, and gas/oil ratio (GOR), have been largely overlooked for constraining geostatistical models because of the complication and difficulty of integrating them. Traditional geostatistical methods for integrating static data are not well suited for integrating dynamic data because dynamic data are nonlinearly related to reservoir properties through the flow equations. Typically, an inverse technique is needed for such integration, in which the flow equations must be solved many times within a nonlinear optimization procedure. In recent years, a number of inverse techniques have been developed and shown capable of preconstraining geostatistical models before they go to the manual history matching phase. Ref. 1 provides a review of these inverse techniques. Two geostatistically based approaches that have shown great potential for the integration of dynamic data are SSC and GM. The SSC method iteratively perturbs the given reservoir model at each gridblock to match the production data while preserving the geostatistical features and static hard/soft data conditioning.2–6 The perturbation is computed through an optimization procedure after a parameterization of the optimization problem with a reduced number of parameters that requires the computation of sensitivity coefficients. The reduced number of parameters to optimize and a fast calculation of the sensitivity coefficients make the inversion computationally feasible. Multiple realizations of the reservoir model can be produced, from which uncertainty can be assessed. Applications of the SSC method to invert permeability distribution from single-phase and multiphase production data have shown their efficiency and robustness.3–6 In this paper, we extend the SSC method to invert lithofacies distributions from production data within the framework of truncated Gaussian simulation. We limit ourselves to sand/shale reservoirs in which permeability is assumed constant within each facies. GM is an evolution and extension of the Gradual Deformation method.7–9 This method generates realizations of reservoir models by an iterative procedure in which, at each iteration, unconditional realizations are linearly and optimally combined into a new realization with a better reproduction of the production data than any other members of the linear combination. Because the linear combination of a few realizations depends only on a few parameters, the optimization procedure is very easy to implement. Our GM algorithm follows the modification of the gradual deformation algorithm by Ying and Gómez-Hernández10 to honor the well data while preserving the permeability variogram. Our modification here is aimed at inverting a lithofacies distribution from production data within the framework of truncated Gaussian simulation. Comparisons of these two methods in generating multiple geostatistical sand/shale reservoir models that honor dynamic production data are made by using both 2D and 3D synthetic data sets. The comparison of the results against the reference models provides direct assessment of the two methods. A thorough comparison of the two methods is made in terms of reproduction of reservoir spatial patterns, matching of production data, implementation issues, feasibility, CPU time, and generality. We also discuss briefly the possible combination of the strength of the two methods to achieve better, more efficient integration of production data. In the following sections, we first recall the methodology of truncated Gaussian simulation to construct a categorical type of reservoir model; then, the SSC and GM methods are presented under the framework of truncated Gaussian simulation to invert lithofacies distributions. Applications of the two methods to invert sand/shale distributions in 2D and 3D reservoir models are made using synthetic data sets, with emphasis on the comparisons of the strengths and weaknesses of the two methods. The production data considered in this paper are fractional-flow rates (water cut) at production wells and water-saturation spatial distribution at a given time in two-phase-flow (oil/water) reservoirs.

More in situ tests are typically carried out over the same volume of soil in comparison to laboratory tests on undisturbed borehole samples. Hence, geostatistical analysis of in situ test records should in principle provide a more accurate and representative overview of spatial variation. A natural probabilistic model for correlated spatial data is the random field. Although the random field provides a concise description of spatial variation, it poses considerable practical difficulties for statistical inference because of the underlying autocorrelation structure. This note presents an extended discussion of the modified Bartlett random field estimation procedure, which is capable of rejecting the null hypothesis of weak stationarity for spatially correlated data. In comparison with simple visual inspection and the standard run test, the modified Bartlett test is shown to provide three advantages: (i) it is a more consistent measure that is unaffected by the vagaries of subjective interpretation; (ii) it is sufficiently discriminative to decide if a section is stationary, even when visual clues are ambiguous; and (iii) it is capable of accommodating realistic constraints (e.g., short record length). The possibility of identifying secondary soil boundaries that may not be readily apparent from visual inspection of cone soundings, its robustness to alternate transformations of the cone data, and the sensitivity of the proposed procedure to different levels of significance are discussed.Key words: geostatistics, random field, stationarity, modified Bartlett test, level of significance, run test.

2006/2007
ITALIANO Nel corso degli ultimi 20 anni, intensi fenomeni erosivi hanno interessato gli arenili situati lungo l’arco costiero nord adriatico e tra le soluzioni impiegate per contrastare tali fenomeni la pratica del ripascimento è stata largamente utilizzata, in quanto permette di riportare le spiagge ad un nuovo equilibrio evitando di provocare impatti significativi sul sistema litoraneo. La problematica maggiore connessa a questo tipo di intereventi è legata alla necessità di ingenti quantità di sabbia dalle caratteristiche granulometriche compatibili con quelle delle spiagge in erosione, con il duplice scopo di ridurre gli impatti negativi sul sistema spiaggia e di minimizzare i costi legati alle operazioni di estrazione e sversamento. Le strategie di gestione delle risorse sabbiose vanno assumendo una notevole importanza all’interno degli strumenti di gestione costiera (Finkl, 1994) e tali strategie, oltre a dover essere basate su estese competenze nel campo della geologia e della sedimentologia, devono prendere in considerazione tutti i fattori ambientali che influenzano il sistema e ne sono influenzati. Problematiche attuali quali l’innalzamento del livello marino e gli effetti sui sistemi costieri, i fenomeni erosivi, la progressiva diminuzione di aree utilizzabili come cave di prestito (sia onshore che offshore) e la creazione di impatti conseguenti alle diverse misure di protezione dei litorali richiedono un approfondito interesse e la ricerca di soluzioni innovative. A partire dalla seconda metà degli anni novanta, ingenti quantitativi di sabbia, pari a 8×106m3 (Consorzio Venezia Nuova, 2006), sono stati sversati sulle spiagge presenti lungo l’arco costiero nord adriatico. Gli interventi, attuati tramite il prelievo di sedimenti presso le coltri sabbiose che ricoprono gli alti fondali delle aree residuali di piattaforma, hanno interessato ad esempio le spiagge di Jesolo, Sottomarina, Pellestrina, Isola Verde. Attualmente, secondo quanto previsto dal Magistrato alle Acque di Venezia tramite il suo concessionario Consorzio Venezia Nuova (2006), è previsto l’utilizzo di circa 3×106m3 di sabbia per interventi di mantenimento, tramite ricariche più frequenti e di minore entità. La pratica di approvvigionamento di sabbie presso le aree relitte di piattaforma ha tuttavia lo svantaggio di essere onerosa, a causa dell’impiego di grandi draghe o di lunghe pipeline per coprire le distanze dalla costa. In tale contesto, un’alternativa vantaggiosa può essere rappresentata dalla ricerca e dall’utilizzo di sabbie dai rialzi morfologici associati alle bocche tidali o eventualmente in alternativa dagli apparati di foce fluviale. Le bocche tidali costituiscono le principali vie di comunicazione marittime da e verso le lagune e necessitano di ordinaria manutenzione nei casi in cui il trasporto longshore sia tale da occludere il canale. In questi contesti uno studio morfodinamico rappresenta una base indispensabile per una corretta pianificazione degli interventi finalizzati al mantenimento dell’ officiosità delle bocche lagunari; la funzionalità e la navigabilità possono essere garantite attraverso le operazioni di dragaggio periodico, con prelievo mirato di sabbie nelle aree di accumulo del delta di riflusso (barra lineare di margine di canale e lobo terminale).Questa operazione si configura dunque come soluzione vantaggiosa per le operazioni di ripascimento di litorali in erosione, in quanto i depositi di ebb-tidal delta generalmente presentano caratteristiche granulometriche compatibili con quelle dei litorali adiacenti. La pratica di escavazione dai bassifondi marini o “ebb-shoal mining” viene largamente effettuata negli Stati Uniti, in Florida e New Jersey ad esempio (Cialone & Stauble, 1998). A seguito della raccolta di dati batimetrici e sedimentologici, in parte forniti dal Magistrato alle Acque - Consorzio Venezia Nuova ed in parte acquisiti attraverso ricerche bibliografiche e due campagne di acquisizione di dati, sono state effettuate numerose elaborazioni con lo scopo di definire le potenzialità di prelievo di sabbie da alcuni apparati di delta di riflusso localizzati lungo l’arco costiero nord adriatico. La ricerca ha permesso inoltre di ampliare la base dati già esistente ed approfondire la morfodinamica delle bocche tidali presenti nel contesto ambientale nord adriatico, nonché le caratteristiche morfologiche degli ebb-tidal delta ad esse associati. Massicci interventi antropici, attuati a partire dallo scorso secolo, hanno portato alla modificazione dei litorali e dell’assetto delle bocche tidali, attraverso la costruzione di strutture permanenti a difesa degli arenili e per consentire la navigazione. Pertanto, le analisi sono state effettuate sia su apparati di bocca tidale in condizioni naturali che su bocche tidali stabilizzate da moli foranei. Infine, è stata analizzata l’evoluzione morfologica recente di alcuni apparati di foce fluviale (Adige, Piave e Sile), al fine di indagare l’eventuale possibilità di estrazione di sedimenti dagli scanni sabbiosi prospicienti tali apparati. Parte integrante del lavoro di ricerca è stata la messa a punto di una specifica procedura geostatistica in ambiente GIS (utilizzando il software ESRI ArcGis™), basata sul metodo elaborato in origine manualmente da Dean and Walton (1973). Una dettagliata analisi morfologica e morfodinamica degli apparati di bocca tidale e foce fluviale è stata effettuata attraverso l’elaborazione di modelli digitali del fondale marino (DEMs), consentendo l’elaborazione di alcune relazioni predittive relative a determinati parametri fisici quali prisma tidale, sezione della bocca e volume del delta di riflusso. Tali risultati sono stati messi a confronto con analoghe elaborazioni, relative a differenti contesti costieri come ad esempio le coste statunitensi e neozelandesi, in modo tale da evidenziare locali fattori morfodinamici responsabili dello sviluppo degli apparati di delta di riflusso. Le numerosi analisi metodologiche, condotte tramite l’estensione Geostatistical Analyst all’interno del software ESRI ArcGis™, hanno permesso di ottenere una valida procedura per il calcolo dei volumi di sabbia depositati nelle strutture di delta di riflusso. Infine, attraverso l’integrazione di tutti i dati raccolti, sia di nuova acquisizione che provenienti da fonti preesistenti, è stato predisposto un geodatabase in GIS, denominato Ebb-delta Geodatabase, che raggruppa tutte le potenziali cave di prestito individuate nonché le caratteristiche granulometriche dei depositi. Relativamente agli apparati deltizi del Piave e dell’Adige, dall’analisi è emersa una situazione critica di erosione dei fondali antistanti le foci, da attribuirsi con una certa sicurezza alla drastica diminuzione dell’apporto di materiale grossolano, avvenuta alla fine degli anni ’50 del secolo scorso e causata dagli interventi antropici sulle lungo le aste fluviali. I delta sommersi, privati di una parte consistente del contributo sedimentario, hanno subito un asporto di quantità significative di sedimento ad opera del moto ondoso e delle correnti marine e le occasionali ricariche, dovute agli eventi di piena, non sono sufficienti a riequilibrare il sistema. Su tale situazione insistono inoltre fenomeni puntuali, come nel caso dell’Adige, dovuti alla recente messa in opera di manufatti che hanno ulteriormente accentuato il processo di erosione dei fondali E’stato ritenuto pertanto che, in ragione di una dinamica sedimentaria legata ad eventi discontinui e a cicli stagionali di erosione-deposizione, ed essendo insufficiente l’apporto solido da parte dei corsi d’acqua, l’estrazione di materiale alle foci del Piave e dell’Adige non sia una soluzione praticabile ai fini del ripascimento di litorali in erosione. Diverso è il caso del fiume Sile, per il quale è stato verificato che l’apporto solido è per sua natura scarso, dunque insufficiente a creare significative anomalie deposizionali nell’area di foce. Gli apparati di delta di riflusso associati alle bocche tidali, sia naturali che stabilizzate, rappresentano al contrario significative trappole sedimentarie in ambiente sottocostiero, caratterizzate da volumi di sabbia compresi tra 270.000m3 e 10×106m3. La procedura geostatistica elaborata, definita procedura geostatica semi-automatica (Authomatic Detrending Procedure-ADP), si è rilevata un utile strumento analitico per la valutazione dell’estensione dei depositi sabbiosi e le elaborazioni effettuate hanno consentito di integrare dati provenienti da fonti non omogenee. Inoltre, lo studio della morfodinamica delle bocche tidali di Lido, Chioggia, Malamocco e Buso ha fornito un’interessante analisi relativa all’evoluzione dei delta di riflusso a seguito della costruzione di moli foranei. Come sottolineato da Carr and Kraus (2001), lo sviluppo verso mare e l’estensione degli apparati di delta di riflusso è determinato dall’ampiezza del prisma di marea, dalla pendenza della piattaforma costiera, e dal processo di confinamento del getto tidale da parte dei moli. Nonostante la casistica esaminata nel corso dello studio sia stata limitata a 11 bocche tidali, la correlazione riscontrata tra i valori di prima tidale ed i volumi ottenuti tramite la procedura geostatistica dimostra che nel caso di bocche tidali non armate i processi tidali siano prevalenti sull’azione del moto ondoso nell’influenzare lo sviluppo delle coltri deposizionali. La relazione V-P elaborata per l’area costiera nord adriatica risulta molto simile a quella ottenuta per le bocche tidali neozelandesi da Hicks and Hume (1996) mentre si discosta in maniera significativa da quelle elaborate per le coste statunitensi da Walton and Adams (1976) e Marino and Mehta (1988). L’utilizzo di una procedura standardizzata, come nel caso della procedura geostatica elaborata all’interno del progetto di ricerca qui presentato, ha permesso di ridurre la soggettività nella stima dei volumi che caratterizzava il metodo proposto originariamente da Dean and Walton (1973). Inoltre, tale procedura si è rivelata particolarmente utile nei casi in cui l’assetto morfologico risulti particolarmente complesso, come nel caso delle bocche tidali armate con moli fortemente aggettanti (Lido, Chioggia, Malamocco, Buso). In questi casi infatti è stata verificata una significativa discordanza tra i valori ottenuti tramite l’applicazione delle relazioni predittive e i risultati delle elaborazioni geostatistiche. Prima degli interventi di stabilizzazione, la maggior parte delle bocche tidali nord adriatiche presentava una configurazione marcatamente asimmetrica, dovuta all’ingente contributo del trasporto litoraneo che ha contributo in numerosi casi alla costruzione di lidi sfasati nella direzione sopraflutto (i.e. Punta Sabbioni; Alberoni; etc). A partire dal diciannovesimo secolo, a seguito delle difficoltà riscontrate per la navigazione dovute all’interramento e/o alla migrazione del canale principale, diverse foci lagunari sono state armate e tale intervento ha comportato una drastica modificazione del regime deposizionale nell’area sottocostiera. Di conseguenza, in relazione alla lunghezza dei moli foranei, la struttura deposizionale di delta di riflusso ha subito un processo di riconfigurazione, generalmente attraverso una traslazione verso mare a maggiori profondità, accompagnata da una parziale erosione dell’accumulo pre-esistente. In numerosi casi inoltre la presenza dei moli ha funzionato come sbarramento per il trasporto litoraneo il quale, prima di venire catturato dal getto tidale ed entrare nel by-pass sedimentario della bocca, ha alimentato l’accrescimento dei litorali posti sopraflutto, come ad esempio nel caso del litorale di Punta Sabbioni adiacente alla bocca di porto di Lido. Ciò ha portato alla formazione di differenti tipologie di delta di riflusso, pesantemente influenzate dall’intervento antropico, per le quali il volume di equilibrio teorico potrebbe essere raggiunto solamente a seguito di un ingente contributo del trasporto longshore, in un arco di tempo considerevole. Uno dei risultati di maggior interesse del presente lavoro risiede dunque nella verifica di uno “stato di immaturità” dei delta di riflusso associati alle bocche tidali stabilizzate, come nel caso della bocca di porto di Lido in cui la costruzione dei moli risale a circa un secolo fa. Come evidenziato da Hansen and Knowles (1988), il processo di confinamento da parte dei moli porta il flusso tidale ad abbandonare il canale principale naturalmente scavato, i canali marginali di flusso e la piattaforma di swash, con effetti sulla pre-esistente struttura deposizionali paragonabili a quelli osservati nei processi di rottura naturale dell’ ebb-tidal delta (ebb-tidal delta breaching; Fitzgerald et al., 1978). Al Lido a seguito della costruzione dei moli la maggior parte dei sedimenti in transito nell’area sottocostiera sono stati depositati sulla spiaggia di Punta Sabbioni, con una conseguente diminuzione del carico sedimentario disponibile per la costruzione del delta di riflusso. Poiché il volume stimato a seguito delle recenti indagini risulta corrispondere a solamente il 10% dell’ipotetico volume di equilibrio, il caso del Lido può essere considerato come un caso di delta “immaturo”, in quanto solo dopo l’esaursi dell’ingente fenomeno di accrescimento dell’arenile di Punta Sabbioni (che risale alla fine degli anni ’60) ha potuto intercettare la gran parte del carico sedimentario associato al trasporto longshore. Numerose incertezze permangono allo stato attuale delle indagini per quanto concerne l’effettivo raggiungimento del volume di equilibrio teorico; le annuali operazioni di escavazione effettuate per mantenere l’officiosità del canale, potrebbero difatti portare ad una configurazione stazionaria del deposito, che potrebbe essere confermata solamente attraverso uno specifico piano di monitoraggio. Gli studi effettuati sulle altre bocche tidali armate localizzate all’interno del contesto in esame hanno in ogni caso evidenziato un comportamento morfodinamico simile; i risultati delle elaborazioni confermano una estensione dei delta di riflusso inferiore a quanto previsto dalle relazioni predittive anche alle foci di Malamocco, Chioggia, e Buso. Per concludere, si sottolinea come la messa a punto di uno specifico database in GIS delle caratteristiche sedimentologiche delle morfologie oggetto di indagine costituisca un efficace strumento di gestione, che permette di associare ai diversi tipi di deposito le informazioni più significative riguardanti la localizzazione; i volumi utilizzabili, etc. Conoscendo le caratteristiche granulometriche dell’arenile da sottoporre all’intervento di ripascimento, un’interrogazione al database permette di identificare le potenziali cave di prestito compatibili, per poi progettare gli interventi più idonei, come ad esempio il prelievo di sedimenti dal canale principale nei casi in cui vi sia un surplus che provoca intralcio alla navigazione, oppure l’estrazione di sabbia nelle aree del delta di riflusso a maggior tasso di crescita (canali marginali flusso e/o lobo terminale). In ogni caso, l’estrazione deve essere limitata sia in estensione che per quanto riguarda lo spessore, per evitare effetti negativi e significativi disequilibri sui fenomeni di rifrazione delle onde e sulla dinamica sedimentaria. Non vi è alcun dubbio che un’attuazione sconsiderata della pratica di estrazione di sabbie dai delta di riflusso possa comportare conseguenze negative sui fondali ed i litorali adiacenti, d’altra parte come suggerito da Hansen and Work (1999) se gli interventi vengono pianificati in modo tale da rimuovere una frazione ridotta del deposito mantenendo così i naturali processi di scambio sedimentario, gli impatti sui litorali adiacenti possono essere di minima portata. La preservazione dell’assetto generale del delta, attraverso l’escavazione di sedimento nella parte terminale verso mare su un’area più estesa in superficie e meno in profondità, può efficacemente ridurre l’alterazione dei pattern di rifrazione delle onde e dei meccanismi di trasporto dei sedimenti.
ENGLISH Beach erosion has strongly affected a large number of beaches along the northern Adriatic coastal area over the past 20 years. Among the different engineering solutions available to contrast coastal erosion, the soft-engineering practice of beach re-nourishment is widely recognized to be a good compromise between desired outcomes and negative environmental impacts. One of the major issue concerning beach nourishment activities is the necessity to find suitable sources of sand, with the purpose of both reducing costs and minimizing environmental impacts. As stated by Finkl (1994), strategies for sand management are becoming increasingly more important as a coastal management tool. Also, the same author suggests that new sand management strategies, based on sound geological principles, must reflect sensitivity to environmental concerns. Rising sea levels, increased shore erosion, decreasing supplies of suitable fill materials (both on-and off-shore) and increasing concerns over environmental impacts associated with coastal protection measures (Finkl, 1994), are some of the reasons for a significant interest in these coastal problems. Along the Venice lagoon barrier islands and adjacent beaches (i.e. Jesolo, Sottomarina, Pellestrina, Isola Verde), 8×106m3 of sand have been extracted and placed for nourishment projects starting from the 1990s. Nowadays the Venice Water Authority (Magistrato alle Acque through its concessionary Consorzio Venezia Nuova, 2006) plans the placement of a total volume of 3 x 106 m3 of sand for beach maintenance, suggesting that critical beach erosion can be mitigated by smaller but more frequent nourishments. Previous re-nourishment projects were carried out through the utilization of sand borrow areas located offshore, at a distance of approximately 20km from the coast, a solution that has high operational costs. An alternative solution may be represented by the use of nearshore sand deposits, located in the proximity of tidal inlets or within the delta front area outside river mouths. Since inlets are the only access pathways between a lagoon and the sea, one of the major problems in terms of navigability is their intrinsic incapacity to maintain a predetermined configuration. Due to the longshore drift, the channel can shift and cause continuous filling of abandoned routes. Moreover, during storms landward pushes can increase the natural rise of the terminal lobe of the ebb delta, enhancing the phenomenon of shoaling at the channel entrance. During the last decades, the practice of ebb-tidal delta mining (Cialone and Stauble, 1998) has been progressively increasing, with the rising demand for suitable beach fill material along barrier islands. Ebb-tidal delta mining gives a new outlook on beach re-equilibrium projects since a large amount of sand, well compatible to native adjacent beaches, is stored by the ebb-tidal delta and easily mined at low cost. Dredging of an inlet opening and channel may also represent a good compromise between navigational needs and the rational use of dredged material. Several potential borrow areas were analysed in the present study, focussing on the evaluation of sand volumes deposited outside tidal inlets and river mouths, as a consequence of existing local hydrodynamic conditions. The coastal area object of the investigation is the northern Adriatic coastal area between the Isonzo and Po rivers, consisting of lagoon-river delta systems fronted by barrier islands and sandbars fed by tidal inlets. New data were collected through bathymetric surveys and sediment sampling and integrated with data from older surveys, thus obtaining a rather complete and uniform catalogue of sand resources. The development of a specific geostatistical procedure was also a main objective of the research, aimed at obtaining reliable results concerning ebb-tidal delta volumes. Considerable changes on the northern Adriatic barrier island systems and associated inlets have occurred over the last century as a result of intense human activity, including construction of permanent structures on both the barriers and the inlets. Those structures are mainly seawalls and groins designed to fix the shoreline and jetties to keep inlets from migrating and to maintain a given channel depth. Both natural and stabilized inlets were investigated, leading to a specific analysis concerning the morphodynamics of stabilized inlets. The present research has been developed through several phases. A detailed analysis of the overall morphology of different nearshore features such as natural and stabilized inlets and river mouths has been conducted, mainly through ESRI ArcGIS™ software, followed by elaborations of predictive numerical relationships concerning inlet parameters (i.e. tidal prism, cross-sectional area and ebb-tidal delta volume). The results obtained were then discussed and compared with analogue relationships elaborated for other environmental settings (i.e. the U.S.A and New Zealand coasts), highlighting the influence of local morphodynamic factors in determining ebb-tidal delta growth along the northern Adriatic coastal area. Methodological analyses concerned a large number of geostatistical tests through ESRI ArcGIS™ Geostatistical Analyst extension, that allowed to obtain a specific procedure for calculating ebb-tidal delta volumes. Finally, with the aim to provide a useful and agile tool for sand resources management, all results were integrated into a GIS geodatabase, named Ebb-delta Geodatabase, which includes the individuated potential sand borrow areas with associated grain size characteristics. The major outcomes of the research are the followings: 1) the seafloor morphologies facing the Piave and Adige river mouths exhibit strong erosional patterns over the last thirty years, possibly as a consequence of a decrease in sediment supply from rivers. Therefore, these areas were not considered suitable sand resources for beach nourishment projects, whereas their morphological evolution testifies that a disequilibrium in sediment supply and deposition is occurring; 2) ebb-tidal deltas represent significant sand sinks along the northern Adriatic coastal area, both the natural and the stabilized ones, with volumes comprised between c.a 270.000m3 and c.a. 10×106m3. 3) the newly-developed semi-authomatic procedure (ADP) provided to be a useful analytical tool for the evaluation of ebb-tidal delta volumes; the development of agile geostatistical procedures allowed the integration and processing of newly collected and older bathymetric and grain size data. Additionally, the study of the morphodynamics of Lido, Chioggia, Malamocco and Buso inlet, provided an analysis of ebb-tidal delta volumes and jetty effects. According to Carr and Kraus (2001) the offshore extent and dimension of the ebb-tidal delta is in great part determined by the magnitude of the tidal prism, the slope of the nearshore shelf, and the ebb-jet confinement caused by jetties. Notwithstanding the limited statistics, the direct proportionality between tidal prism and ebb-tidal delta volumes obtained from the application of the ADP on the bathymetric dataset, as well as the high correlation coefficient, demonstrates that natural or almost natural inlets in the northern Adriatic tend to build ebb-tidal deltas which are strongly influenced by tidal processes. Thus the effects of storm induced wave winnowing and longshore sedimentary drift may be considered uniformly distributed, since scattering in the prism vs. ebb-tidal delta volumes relationship is negligible. The V-P relationship of ebb tidal delta volumes in the northern Adriatic is very similar to that obtained by Hicks and Hume (1996), but significantly different from that found by Walton and Adams (1976) and Marino and Mehta (1987) in the United States. The use of a standardized procedure, as in the case of the geostatistical application here proposed, reduces the subjectivity in the calculation of the ebb-tidal deltavolume which occurs when using the Dean and Walton method (1973). The ADP could also be a useful method for a step-by-step preliminary test on ebb-tidal delta structure determination as in the case of complicated bathymetric frameworks. Equilibrium conditions based on delta volume vs. tidal prism relationships constructed for natural or almost natural northern Adriatic inlets, may be used to infer the hypothetical delta volume also for jettied inlets. During the past, many northern Adriatic inlets were strongly asymmetrical, because of significant longshore transport processes that gave rise to large up-drift coastal offset. Since the 19th Century, owing to great difficulties in navigation through the main channel, some inlets were fixed by jetties. Depending on the jetty length, precisely on the offset between shoreline and jetty apex, the ebb-tidal delta may re-shape or completely erode, and thus begin to re-form offshore, shifting to a distance equal to that of the jetty length. This may cause a delay in ebb-tidal delta formation, since the longshore sediment input is not immediately captured by the inlet system and stored in the ebb delta. In fact, the up-drift beach will accrete until the sediments are able to by-pass the jetty, thus entering in the inlet sedimentary budget. What can be observed is a large variety of new “human-induced” ebb deltas, whose equilibrium volumes may be reached only when a large amount of transported long-shore sediment has been trapped for long time. The “immaturity” status of the new ebb-tidal deltas is a major result, for the case of Lido inlet, the largest in the north Adriatic, where jetties were constructed about one century ago. According to Hansen and Knowles (1988) confinement of the flow by jetty construction has resulted in tidal flow abandonment of the natural main ebb channel, swash platform and marginal flood channels, resulting in effects similar to those observed in natural ebb-tidal delta breaching (Fitzgerald et al., 1978). After jetty construction, sediments were stored in the up-drift area of Punta Sabbioni and caused the accretion of that beach, resulting in a starved status of the ebb-tidal delta potential area. Considering that the present ebb-tidal delta volume accounts for only 10% of the equilibrium hypothetical volume, Lido inlet can be seen as a typical case of immature ebb-tidal delta, which only recently has significantly grown offshore due to the jetty fixation. Some doubts arise from the possibility that the delta volume will increase, owing to the periodic dredging operations that are done for navigational improvement. This practice may lead to a stationary configuration of the ebb tidal delta, that can be tested only through a specific monitoring plan. Additional studies concerning the behaviour of jettied inlets provided similar results in the cases of Malamocco, Chioggia and Buso inlets. Data analysis confirms the limited ebb-tidal delta extension also in these latter cases, and a morphodynamic response comparable to the one observed at Lido. The ebb-tidal delta sediment inventory that was processed through GIS has very high versatility and can associate type of deposits (grain-size, sorting) with its location and volume “excess”. Once the required physical parameters of the material are known for a beach that needs to be re-nourished, a GIS query could identify different potential borrow areas and subsequent actions can be planned. The suitability of a morphological artificial re-shaping may be planned, by mainly using sand from growing areas, i.e. the channel margin linear bar and terminal lobe, as well as the sedimentary surplus from navigational maintenance located inside the outer part of the main ebb channel. In any case, dredging must be limited both in extension and thickness, in order to minimize the already cited effects on wave and sedimentary dynamics. The use of ebb-tidal delta sediment as a source for beach nourishment material has and will be controversial. However, as suggested by Hansen and Work (1999) there is a natural variability to these inlets systems, and if artificial bypassing practices mimic the natural processes by removing a small percent of the delta on an annual basis, there is likely to be minimal adverse impact to adjacent shorelines. Mining the seaward edge of the delta over a large area would maintain the overall geomorphology of the inlet and would reduce the possibility of severely altering nearshore refraction and sediment transport patterns
XX Ciclo
1976

Arsenic (As) contamination of soils is a major environmental problem due to its toxic and carcinogenic nature. Historical use of As-containing pesticides has resulted in the contamination of soils with high and variable concentrations of As in many parts of Australia. Phytoremediation using As-hyperaccumulating ferns can be potentially utilised as an environmental friendly and low-cost remediation technology to phytoextract As from soils at sites containing elevated and varying concentration of As. The spatial variability of total and phosphate-extractable As concentrations was evaluated in soil adjacent to a cattle-dip site located at Wollongbar in northern NSW, Australia. The results from the linear mixed model showed that total (0–0.2 m) and phosphate-extractable (0–0.2, 0.2–0.4 and 0.4–0.6 m depths) As concentrations in the soil adjacent to the dip site varied greatly and increased significantly (P = 0.004–0.048) toward the dip site, indicating that As variability in soil was spatially correlated with distance from the dip. The data suggest that 5 samples should be required to assess the soil contamination level (mean = 826 mg kg–1) and 15 samples would be required to evaluate the effects of phytoremediation of As-contaminated site. The proposed guidelines on sampling requirements are important to estimate the variability in As contamination levels around other cattle-dip sites and to monitor changes in soil As content from phytoremediation activities. Ensuing study compared the phytoremediation potential of Pityrogramma calomelanos var. austroamericana (gold dust fern) against the well-known Pteris vittata (Chinese brake fern) over a 27-month duration grown at the cattle-dip site described earlier. The ferns were planted in January 2009 and harvested following 10, 22 and 27 months of growth. After 10 months of growth (short-term data), P. calomelanos var. austroamericana produced significantly higher frond dry biomass, possessed higher frond As concentration and removed more As in fronds (mean = 130 g plant–1, 887 mg kg–1 and 124 mg plant–1, respectively; P < 0.05) than P. vittata (mean = 81 g plant–1, 674 mg kg–1, 57 mg plant–1). Further samplings up to 27 months (long-term data) confirmed the earlier results that the mean frond dry biomass, As concentration and As uptake were significantly higher in P. calomelanos var. austroamericana than P. vittata. In the three harvests over the 27-month period, P. calomelanos var. austroamericana removed (8,053 mg As) 2.65 times higher As than P. vittata (3,042 mg As). For the surface (0−20 cm) and subsurface (40−60 cm) layers, the mean total soil As content was significantly (P < 0.05) reduced by 49% and 63%, respectively, using P. calomelanos var. austroamericana; and 17% and 15%, respectively, by P. vittata (P > 0.05). It is estimated that P. calomelanos var. austroamericana would take approximately 6 years to decrease mean total As content below the ecological investigation level (EIL; 20 mg kg−1) limit in the surface and subsurface soils, whereas P. vittata would require 13−15 years to achieve this target. The field experiment results suggest that P. calomelanos var. austroamericana is better suited than P. vittata for the phytoremediation of As-contaminated soils under the experimental conditions existing at the site. The potential of mid infrared (MIR) spectroscopy in combination with partial least squares (PLS) regression was investigated to estimate the total As content in a large number of soil samples collected from a highly variable As-contaminated dip site. The MIR-PLS calibration model developed excluding spectral outliers (n = 149) was robust with an acceptable reliability (coefficient of determination; R2c = 0.73; residual prediction deviation; RPDc = 1.94) to estimate total soil As content. The validation of calibration model using a separate set of unknown soil samples (n = 149; validation set) showed R2v and RPDv values of 0.63 and 1.66, respectively. The results indicate an acceptable prediction of total As content in unknown samples, suggesting that MIR-PLS based model is capable of estimating total soil As and possibly be used in certain situations; for example to estimate soil As concentration at a highly variable site, where a large number of samples needs to be analysed. The solid-phase speciation and plant availability of As in contaminated soils was determined using combination of a sequential extraction procedure (SEP), X-ray absorption near edge structure (XANES) spectroscopy and As plant uptake using Brassica juncea as a test plant. Arsenic was found to be predominantly associated with amorphous Fe oxides in arsenate (AsV) form; in few samples As was present in arsenite (AsIII) form. The concentration of As in plant shoots showed significant (P < 0.001−0.05) correlations with the exchangeable As (r = 0.85), and amorphous Fe oxides associated As evaluated by the SEP (r = 0.67) and XANES spectroscopy (r = 0.51). The results suggest that As in these fractions is readily available for plant uptake and may pose potential risk to the environment. Such detailed analysis for As speciation and phytoavailability is vital for the management and rehabilitation of As-contaminated soils.
Higher Education Commission of Pakistan, NSW Government through its environmental trust, Australian Synchrotron Research Program, for enabling me to travel to the Australian National Beamline Facility in Tsukuba (Japan) for performing my experiment (Project AS093/ANBF1851)

Geostatistics is an increasingly important tool for developing an integrated reservoir description. Though Applied Geostatistics for Reservoir Characterization is written to illustrate the importance of geostatistics in improving the reservoir characterization process, it does not require any prior knowledge of statistics or advanced mathematics. Emphasis is placed on intuitive understanding of procedure rather than on mathematical details. Each chapter has an associated appendix in which additional mathematical details are provided. Several numerical and field examples, as well as a large number of illustrations, are provided to explain the strengths and weaknesses of different methods. Media Resources (http://go.spe.org/AGRCmedia)

AbstractMachine learning is a broad field of study that can be applied in many areas of science. In mining, it has already been used in many cases, for example, in the mineral sorting process, in resource modeling, and for the prediction of metallurgical variables. In this paper, we use for defining estimation domains, which is one of the first and most important steps to be taken in the entire modeling process. In unsupervised learning, cluster analysis can provide some interesting solutions for dealing with the stationarity in defining domains. However, choosing the most appropriate technique and validating the results can be challenging when performing cluster analysis because there are no predefined labels for reference. Several methods must be used simultaneously to make the conclusions more reliable. When applying cluster analysis to the modeling of mineral resources, geological information is crucial and must also be used to validate the results. Mining is a dynamic activity, and new information is constantly added to the database. Repeating the whole clustering process each time new samples are collected would be impractical, so we propose using supervised learning algorithms for the automatic classification of new samples. As an illustration, a dataset from a phosphate and titanium deposit is used to demonstrate the proposed workflow. Automating methods and procedures can significantly increase the reproducibility of the modeling process, an essential condition in evaluating mineral resources, especially for auditing purposes. However, although very effective in the decision-making process, the methods herein presented are not yet fully automated, requiring prior knowledge and good judgment.

Abstract Chapter 11 addresses a topic that is not traditionally described in books about random processes: spatial analysis. It is nevertheless an important subject dealing with the application of statistical concepts to properties varying in space. The Chapter provides an introduction to geostatistical concepts and then present a novel approach, where spatial and temporal analysis are combined into a stochastic analysis of spatio-temporal processes. At the end of the chapter, the optimization procedure for spatial parameter is computed also with genetic algorithm, showing the possibility of connecting and applying various techniques presented in the book.

The problem of estimation of a coregionalization of size q using cokriging will be discussed in this chapter. Cokriging—a multivariate extension of kriging—is the usual procedure applied to multivariate regionalized problems within the framework of geostatistics. Its fundament is a distribution-free, linear, unbiased estimator with minimum estimation variance, although the absence of constraints on the estimator is an implicit assumption that the multidimensional real space is the sample space of the variables under consideration. If a multivariate normal distribution can be assumed for the vector random function, then the simple kriging estimator is identical with the conditional expectation, given a sample of size N. See Journel (1977, pp. 576-577), Journel (1980, pp. 288-290), Cressie (1991, p. 110), and Diggle, Tawn, and Moyeed (1998, p. 300) for further details. This estimator is in general the best possible linear estimator, as it is unbiased and has minimum estimation variance, but it is not very robust in the face of strong departures from normality. Therefore, for the estimation of regionalized compositions other distributions must also be taken into consideration. Recall that compositions cannot follow a multivariate normal distribution by definition, their sample space being the simplex. Consequently, regionalized compositions in general cannot be modeled under explicit or implicit assumptions of multivariate Gaussian processes. Here only the multivariate lognormal and additive logistic normal distributions will be addressed. Besides the logarithmic and additive logratio transformations, others can be applied, such as the multivariate Box-Cox transformation, as stated by Andrews et al. (1971), Rayens and Srinivasan (1991), and Barcelo-Vidal (1996). Furthermore, distributions such as the multiplicative logistic normal distribution introduced by Aitchison (1986, p. 131) or the additive logistic skew-normal distribution defined by Azzalini and Dalla Valle (1996) can be investigated in a similar fashion. References to the literature for the fundamental principles of the theory discussed in this chapter were given in Chapter 2. Among those, special attention is drawn to the work of Myers (1982), where matrix formulation of cokriging was first presented and the properties included in the first section of this chapter were stated.

The chapter tells about a procedure for investigating the coherence of the relationship between a “wide” mean of distance and the geography of real estate value. Many authors consider that real estate value can depend on distance from some reference point, and its variation can be linear. Such conviction leads to the use of geostatistical approaches based on kriging techniques. At the same time, the literature teaches that the market shows a higher value where several amenities are coexisting. But in those urban realities where the number of central points and the number of amenities is high, the complexity does not support the construction of models, and this complexity leads to a different concept of identity as synthesis of distance, borders, and concentration. The use of fuzzy cluster can support the analysis. This chapter gives a brief example about how this works in the case of New York core.

Abstract At present, the geological model of the Groningen gas field is one of the largest high-quality open data sets in the oil and gas industry. The purpose of this study is to demonstrate the possibilities of improving the Groningen model, as well as to illustrate some open questions regarding the application of geostatistics in a typical geomodeling workflow in terms of this model. The model was analyzed, and the analysis showed significant uncertainty in the three-dimensional interpolation of reservoir properties. The properties were modeled using geostatistical simulation; the variability of the modeled parameters was assumed stationary over the entire modeled area. This assumption is not always true even for local objects, and in this case the model covers almost the whole region. The next step was to check whether the variability of the properties was stationary according to the initial data. The verification was carried out using model areas with the size of a area corresponding to that of a typical field. The main practical result is a demonstration of a way to increase the reliability of the geological model of the Groningen field considered in the study by rejecting geostatistical simulation, which is not applicable in this case, and employing one of the other methods of property propagation instead. Since this model can be used as a basis for various geomechanical simulations necessary to understand the nature of technogenic seismicity associated with the development of this field, ensuring maximum reliability of the model is a very important issue. Another result of this study is a demonstration of a set of checks necessary to assess the applicability of geostatistical tools. Such a set of checks can be effectively applied in the modeling of any field, both in the course of simulation work to prevent distortions in the model and for examination of existing models. The study showcases the possibility of performing such checks using specialized procedures, as well as with the help of standard geostatistical tools available in most geological modeling packages. For the first time, the applicability of geostatistical tools in terms of the underlying geostatistical concept of the stationarity hypothesis is considered in detail with a real field serving as the illustration. The study demonstrates the necessary verification tools and considers the issues of compiling the optimal set of such checks.

Abstract 3D printing is a type of additive manufacturing technology that allows for digital 3D models to be made into physical objects out of a wide range of thermoplastics, resins, and occasionally metals. In previous years, 3D printing models at high-resolution suitable for oil and gas research was either time consuming, cost-prohibitive, or limited to a small model build volume. However, the rapid advancement in resin 3D printing technology recently has allowed for a significant increase in production speeds and model size at little cost. In this study, we utilized 3D printed rough-wall fracture panels in a large-scaled proppant transport apparatus to evaluate the feasibility of repeatable and realistic experimental investigation by the 3D printing technology. Understanding proppant transport in hydraulically created fractures helps to answer the questions about proppant distribution, resultant fracture conductivity, effectiveness of fracture fluid and additives, and all leads to fracture treatment efficiency. In the past, lab experiments showed that fracture topography plays an important role on fracture conductivity, and the characteristics of fracture surfaces have been grouped as random distribution, channel, wavy and ledge (step-change). These surface features can be described by geostatistical parameters. For large-scale proppant transport, the realistic surfaces are difficult to create, and thus most studies have used smooth-surfaced parallel acrylic panels for the fracture walls. Stereolithography (SLA) resin 3D printers produce a physical model by using an ultraviolet light source to selectively illuminate and cure a photopolymer onto a travelling build platform. The physical models are based on a computer-generated surface with controlled statistical definition. We have successfully printed panels to build a 4ft X 2ft main fracture with a smaller fracture intersecting orthogonally. The panels are carefully printed with transparent resin to allow for video recording. Initial tests showed the mechanical integrity of printed fractures and proppant transport results. This paper describes the detailed procedure of generating fractures by 3D printing, experimental setup and the test results of proppant transport.

Policymakers, stakeholders and rural inhabitants must be aware of the relevance of soil erosion as an irreversible landdegradation process. This is key to achieve the land degradation neutrality challenge and the sustainability of humankindand natural ecosystems. Agricultural areas are being affected by soil erosion threatening soil quality and, subsequently,food security. Therefore, it is necessary to develop new techniques and methods visually friendly and easy to be accessedto survey and assess the soil erosion concerns. ISUM (Improve Stock Unearthing Method) is a well-contrasted procedureto estimate and map soil mobilisation and erosion rates. To achieve this goal, using the plant graft union as a biomarkerconducting in situ topographical measurements along perpendicular transects allow us to i) explain key factors related tothe activation of soil erosion processes such as tillage, the age of plantation, parent material or hillslope positions; ii)complete other well-contrasted methods such as RUSLE (Revised Soil Loss Equation), IC (Index of connectivity) orStructure from Motion; and, iii) identify hotspot areas affected by soil depletion, accumulation or mobilisation. In thisconference, we will show how we developed a new improvement of this method in different crops (vineyards, citrus,persimmons or almonds), under different environmental conditions (parent material, vine ages, soil management, or slopeangle) with diverse geomatic procedures (interpolation methods and geostatistical analysis, topographical measurementsand models) using GIS techniques.