Olive yield and future climate forcings

The rainfall reduction and the temperature increase forecasted for Mediterranean regions would likely increase the vegetation water stress and decrease productivity in rainfed agriculture. Olive trees, which have traditionally been grown under rainfed conditions, are one of the most characteristic tree crops from the Mediterranean not only for economical importance but also for minimizing erosion and desertification and for improving the carbon balance of these areas. In order to simulate how climatic change could alter soil moisture dynamics, biomass growth and fruit productivity, a water driven crop model is used in this study. The model quantitatively links olive yield to climate and soil moisture dynamics using an ecohydrological model, which simulates soil moisture, evapotranspiration and assimilation dynamics of olive orchards. The model is able to explicitly reproduce two different hydrological and climatic phases in Mediterranean areas: the well-watered conditions and the actual conditions, where the limitations induced by soil moisture availability are taken into account. Annual olive yield is obtained by integrating the carbon assimilation during the growing season, including the effects of vegetation water stress on biomass allocation. The numerical model, previously calibrated on an olive orchard located in Sicily (Italy) with a satisfactory reproduction of historical olive yield data, has been forced with future climate scenarios generated using a stochastic weather generator which allows for the downscaling of an ensemble of climate model outputs. The stochastic downscaling is carried out using simulations of some General Circulation Models adopted in the IPCC 4AR for future scenarios. In particular, 2010, 2050, 2090 and 2130 scenarios have been analyzed

Combined experimental-theoretical study of the OH + CO → H + CO2 reaction dynamics

A combined experimental−theoretical study is performed to advance our understanding of the dynamics of the prototypical tetra-atom, complex-forming reaction OH + CO → H + CO 2, which is also of great practical relevance in combustion, Earth’s atmosphere, and, potentially, Mars’s atmosphere and interstellar chemistry. New crossed molecular beam experiments with mass spectrometric detection are analyzed together with the results from previous experiments and compared with quasi-classical trajectory (QCT) calculations on a new, fulldimensional potential energy surface (PES). Comparisons between experiment and theory are carried out both in the center-of-mass and laboratory frames. Good agreement is found between experiment and theory, both for product angular and translational energy distributions, leading to the conclusion that the new PES is the most accurate at present in elucidating the dynamics of this fundamental reaction. Yet, small deviations between experiment and theory remain and are presumably attributable to the QCT treatment of the scattering dynamics

Detecting hydrological changes through conceptual model

Natural changes and human modifications in hydrological systems coevolve and interact in a coupled and interlinked way. If, on one hand, climatic changes are stochastic, non-steady, and affect the hydrological systems, on the other hand, human-induced changes due to over-exploitation of soils and water resources modifies the natural landscape, water fluxes and its partitioning. Indeed, the traditional assumption of static systems in hydrological analysis, which has been adopted for long time, fails whenever transient climatic conditions and/or land use changes occur. Time series analysis is a way to explore environmental changes together with societal changes; unfortunately, the not distinguishability between causes restrict the scope of this method. In order to overcome this limitation, it is possible to couple time series analysis with an opportune hydrological model, such as a conceptual hydrological model, which offers a schematization of complex dynamics acting within a basin. Assuming that model parameters represent morphological basin characteristics and that calibration is a way to detect hydrological signature at a specific moment, it is possible to argue that calibrating the model over different time windows could be a method for detecting potential hydrological changes. In order to test the capabilities of a conceptual model in detecting hydrological changes, this work presents different “in silico” experiments. A synthetic-basin is forced with an ensemble of possible future scenarios generated with a stochastic weather generator able to simulate steady and non-steady climatic conditions. The experiments refer to Mediterranean climate, which is characterized by marked seasonality, and consider the outcomes of the IPCC 5th report for describing climate evolution in the next century. In particular, in order to generate future climate change scenarios, a stochastic downscaling in space and time is carried out using realizations of an ensemble of General Circulation Models (GCMs) for the future scenarios 2046-2065 and 2081-2100. Land use changes (i.e. changes in the fraction of impervious area due to increasing urbanization) are explicitly simulated, while the reference hydrological responses are assessed by the spatially distributed, process-based hydrological model tRIBS, the TIN-based Real-time Integrated Basin Simulator. Several scenarios have been created, describing hypothetical centuries with steady conditions, climate change conditions, land use change conditions and finally complex conditions involving both transient climatic modifications and gradual land use changes. A conceptual lumped model, the EHSM (EcoHydrological Streamflow Model) is calibrated for the above mentioned scenarios with regard to different time-windows. The calibrated parameters show high sensitivity to anthropic variations in land use and/or climatic variability. Land use changes are clearly visible from parameters evolution especially when steady climatic conditions are considered. When the increase in urbanization is coupled with rainfall reduction the ability to detect human interventions through the analysis of conceptual model parameters is weakened

Assessing the hydrological changes due to land use alterations

The increase of urbanized areas and, consequently, of the impervious surfaces in land-use distributions may have important implications on the basin hydrological response. As a direct impact, the increase of cemented areas reduces the available storage volume for water in the watershed, which in turn exacerbates the runoff generation. Additionally, drainage pathways can be altered and the travel time to the watershed outlet considerably speeded up, with impacts on the hydrograph characteristics. The complex interactions among different hydrological processes make the estimations of the hydrological changes highly non linear. The aim of this work is using an advanced physically-based and distributed model, i.e. tRIBS (TIN-based real-time integrated basin simulator), to evaluate how the changes in the hydrological properties affect the watershed response not only in terms of outlet discharge but also in terms of spatial distribution of the main hydrological variables (e.g., soil moisture patterns, groundwater level, etc...). Moreover, we evaluate whether and how the spatial pattern of the impervious areas increase affects the change in the hydrological response. The work has been carried out on the Baron Fork watershed, located in OK (USA), characterized by an area of about 800 km2 and for which the tRIBS model was successfully calibrated in the past. Specifically, we eval- uate the hydrological response for different extreme events typical of the area and different land-use configurations

Modeling the hydrological and mechanical effect of roots in shallow landslide analysis

5siopenopenARNONE, Elisa; CARACCIOLO, Domenico; NOTO, Leonardo; Preti, F; Bras, RLArnone, Elisa; Caracciolo, Domenico; Noto, Leonardo; Preti, F; Bras, R

Performances of GPM satellite precipitation over the two major Mediterranean islands

This study aims to assess the reliability of satellite-precipitation products from the Global Precipitation Measurements (GPM) mission in regions with complex landscape morphology. Our analysis is carried out in the European mid-latitude area, namely on the two major islands of Mediterranean Sea, i.e. Sardinia and Sicily (Italy). Both islands experience precipitation originating from the interaction of steep orography on the coasts with winds carrying humid air masses from the Mediterranean Sea. The GPM post real-time IMERG (Integrated Multi-satellitE Retrievals from Global Precipitation Measurement) “Final” run product at 0.1° spatial resolution and half-hour temporal resolution have been selected for the two-year 2015–2016 period. Evaluation and comparison ofthe selected product, withreferenceto raingauge network data, areperformed athourly and daily time scales using statistical and graphical tools. The influences of morphology and land-sea coastal area transition on the reliability of the GPM product have been analysed. Confirming previous studies, results showed that GPM satellite data slightly overestimate rainfall over the study areas, but they are well correlated with the interpolated raingauge data. Metrics based on occurrences above a given threshold and on total volume above the same threshold were applied and revealed better performances for the latter ones. Applying the same metrics we show how GPM performances improve as the temporal aggregation increases. Several drawbacks were detected in the coastal areas, which were characterized by worse performances than internal areas. Statistics are generally very similar for the two considered case studies (i.e., Sardinia and Sicily) except for correlation between topography and accuracy of GPM products, which was slightly higher for Sardinia

L’INFLUENZA DELLA MORFOLOGIA SULLA DISTRIBUZIONE DELLE PIOGGE INTENSE

Le precipitazioni intense costituiscono uno dei principali pericoli naturali perché sono all’origine di processi, come innesco di frane o piene improvvise, che possono rappresentare una grave minaccia per la vita umana. Il problema di determinare la variazione spaziale delle precipitazioni intense e in particolare, di indagare sulle relazioni che intercorrono tra queste e la morfologia del territorio, è molto importante soprattutto per gli studi connessi alla realizzazione di efficienti sistemi di allerta e di allarme. Tuttavia la variabilità delle piogge intense con la morfologia è scarsamente studiata in idrologia. In questo lavoro si intende affrontare l’argomento a scala regionale, assumendo che le precipitazioni intense siano rappresentate dalle curve di probabilità pluviometrica che forniscono il quantile Tennale di assegnata durata come prodotto di un coefficiente di crescita in frequenza per una relazione di potenza che serve a riscalare le medie orarie nelle durate maggiori tramite due parametri, a e n. In tal modo lo studio può essere ricondotto all’analisi della variazione di questi due parametri in funzione di alcuni caratteri morfologici e fisiografici. Lo studio è stato condotto sui dati provenienti da 276 stazioni pluviografiche funzionanti sul territorio siciliano. E’ stata utilizzata sia la regressione stepwise sia la Geographically Weighted Regression (GWR) pervenendo a risultati interessanti