Gaussian Process priors with uncertain inputs? Application to multiple-step ahead time series forecasting

We consider the problem of multi-step ahead prediction in time series analysis using the non-parametric Gaussian process model. k-step ahead forecasting of a discrete-time non-linear dynamic system can be performed by doing repeated one-step ahead predictions. For a state-space model of the form y t = f(Yt-1 ,..., Yt-L ), the prediction of y at time t + k is based on the point estimates of the previous outputs. In this paper, we show how, using an analytical Gaussian approximation, we can formally incorporate the uncertainty about intermediate regressor values, thus updating the uncertainty on the current prediction

Rainfall thresholds derivation for warning pluvial flooding risk in urbanised areas

Aim of this work is the development of an operational tool for pluvial flooding warning in an urban area based on off-line rainfall thresholds derived by coupling a rainfall-runoff modelling and a hydraulic routing. The critical conditions considered for issue flood warnings were not only based on the water stage, but also on the extension of the flooded area. Further, a risk assessment framework for quantifying the reliability of the rainfall thresholds has been included; rainfall thresholds used in pluvial flooding warning should be influenced by the uncertainties in the rainfall characteristics (i.e. rainfall duration, depth and storm pattern). This risk assessment framework incorporates the correlated multivariate Monte Carlo simulation method, an hydraulic model for the simulation of rainfall excess propagation over surface urban drainage structures, i.e. streets and pathways. Thresholds rainfall are defined using a number of inundation criteria, to analyze the change in the rainfall threshold due to various definitions of inundation. Starting from estimated water stages and flooded area from inundation simulation rainfall thresholds can be obtained according a specific inundation criterion, including, together, a critical water depth and a critical flooding area. Finally, the second phase concerns the imminence of a possible hydrological risk by comparing the time when cumulative rainfall and rainfall thresholds meet to each other. The developed procedure has been applied to the real case study of Mondello catchment in Palermo (Italy)

Formulación de un aderezo a base de zapallo loche utilizando criterios de conservación y aceptación sensorial

In this investigation, a dressing based on loche squash was developed. Initially, nine formulations ere designed, being acidified with acetic acid until reaching a pH of 4.4. Sensory analyses were performed in four sessions by an untrained panel which assessed the characteristics of the formulations: appearance, aroma and flavor, the formulation with the highest degree of satisfaction being determined through the Analysis of Variance (ANOVA) and the Least Significant Difference (LSD) tests. Then, the formulation of greater satisfaction was subjected to three different heat treatments: 85°C for 10 min, 90°C for 6 minutes and 95°C for 3 minutes. Finally, two quality criteria were evaluated: Microbiological (mesophilic viable microorganisms) and enzymatic (pectinesterase), choosing the treatment of 90 °C for 6 minutes, which was subjected to physical and chemical tests. As a result, a loche squash dressing was obtained, preserving its initial organoleptic characteristics and achieving a safe product of good taste.En esta investigación se desarrolló un aderezo a base de zapallo loche; diseñándose nueve formulaciones iniciales, las cuales fueron acidificadas con ácido acético hasta llegar a un pH de 4.4. Se realizaron análisis sensoriales, donde jueces no entrenados, evaluaron en 4 sesiones los atributos de las formulaciones: Apariencia, aroma y sabor; determinando la formulación con mayor grado de satisfacción, a través  de Análisis de varianza (ANOVA) y Diferencia mínima significativa (DMS). Por consiguiente, la formulación de mayor grado de satisfacción, fue sometida a tres diferentes tratamientos térmicos: 85º C a 10 minutos; 90º C a 6 minutos y  95º C a 3 minutos.  Por último, se evaluaron dos criterios de calidad: Microbiológicos (microorganismos mesófilos viables) y enzimático (pectinesterasa), escogiendo el tratamiento de 90º C por 6 minutos, siendo sometido a pruebas físicas y químicas. Como resultado, se obtuvo un aderezo a base de zapallo loche, conservando características organolépticas iniciales y logrando un producto inocuo de  agradable sabor

Derivation of rainfall thresholds for pluvial flood risk warning in urbanised areas

In the recent past throughout the Mediterranean area, many extreme events such as floods, debris flows and landslides occurred. Mediterranean ephemeral streams have specific features compared to other river systems; their basins are small and highly torrential and may generate flash-floods (Camarasa-Belmonte & Soriano-Garcia, 2012). Moreover, the rapid transformation processes of urban areas induced the increase of catchment imperviousness and the derived increase of surface runoff generated during rainfall events. However, flooding events in urban areas occur quite frequently as a consequence of rain events of lower intensity than the design one, even in case of correct network dimensioning. The use of a reliable flood forecasting model in urban areas can play an important role in managing land and water resources. The purpose of this work is the development of a Decision Support System (DSS) for flash flood warning in an urban area. Usually, flood warning systems are based on on-line hydrological and/or hydraulic models in order to provide forecasts of water stages or discharges at critical river sections (Martina et al., 2006; Diakakis, 2012; Wu et al., 2015). This procedure is inappropriate for flash flood warning in urban areas or in catchments with a small area. According to the approach proposed by [Amadio et al., 2003; Wu et al., 2015], in this study the rainfall threshold has been estimated in an urban area by coupling results of hydro-dynamic model in terms of water stage and flooding area. Particularly, dependency of the antecedent soil moisture conditions has been neglected because urban areas are characterized by imperious surfaces This study proposes a methodology to point out in urban areas rainfall thresholds used in flash flood warning which should be influenced by the uncertainties in the rainfall characteristics, including rainfall duration, depth and storm pattern. Particularly, the methodology here developed has a modular structure consisting of different modules: synthetic hyetographs definition to gain the hydrological input to the hydraulic model; transformation of flood discharge to inundated area through a two-dimensional hydraulic model the FLURB-2D model (Aronica & Lanza, 2005) and, finally, quantification of threshold rainfall associated with specific inundation criteria

Estimation of synthetic flood design hydrographs using a distributed rainfall–runoff model coupled with a copula-based single storm rainfall generator

In this paper a procedure to derive synthetic flood design hydrographs (SFDH) using a bivariate representation of rainfall forcing (rainfall duration and intensity) via copulas, which describes and models the correlation between two variables independently of the marginal laws involved, coupled with a distributed rainfall–runoff model, is presented. Rainfall–runoff modelling (R–R modelling) for estimating the hydrological response at the outlet of a catchment was performed by using a conceptual fully distributed procedure based on the Soil Conservation Service – Curve Number method as an excess rainfall model and on a distributed unit hydrograph with climatic dependencies for the flow routing. Travel time computation, based on the distributed unit hydrograph definition, was performed by implementing a procedure based on flow paths, determined from a digital elevation model (DEM) and roughness parameters obtained from distributed geographical information. In order to estimate the primary return period of the SFDH, which provides the probability of occurrence of a hydrograph flood, peaks and flow volumes obtained through R–R modelling were treated statistically using copulas. Finally, the shapes of hydrographs have been generated on the basis of historically significant flood events, via cluster analysis. <br><br> An application of the procedure described above has been carried out and results presented for the case study of the Imera catchment in Sicily, Italy