Improving flow forecasting by error correction modelling in altered catchment conditions          下载免费PDF全文

Francesca Pianosi  Andrea Castelletti  Leonardo Mancusi  Elisabetta Garofalo 《水文研究》2014,28(4):2524-2534

Despite human is an increasingly significant component of the hydrologic cycle in many river basins, most hydrologic models are still developed to accurately reproduce the natural processes and ignore the effect of human activities on the watershed response. This results in non‐stationary model forecast errors and poor predicting performance every time these models are used in non‐pristine watersheds. In the last decade, the representation of human activities in hydrological models has been extensively studied. However, mathematical models integrating the human and the natural dimension are not very common in hydrological applications and nearly unknown in the day‐to‐day practice. In this paper, we propose a new simple data‐driven flow forecast correction method that can be used to simultaneously tackle forecast errors from structural, parameter and input uncertainty, and errors that arise from neglecting human‐induced alterations in conceptual rainfall–runoff models. The correction system is composed of two layers: (i) a classification system that, based on the current flow condition, detects whether the source of error is natural or human induced and (ii) a set of error correction models that are alternatively activated, each tailored to the specific source of errors. As a case study, we consider the highly anthropized Aniene river basin in Italy, where a flow forecasting system is being established to support the operation of a hydropower dam. Results show that, even by using very basic methods, namely if‐then classification rules and linear correction models, the proposed methodology considerably improves the forecasting capability of the original hydrological model. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Evidence of scavenging on remains of the gomphothere Haplomastodon waringi (Proboscidea: Mammalia) from the Pleistocene of Brazil: Taphonomic and paleoecological remarks     

Victor Hugo Dominato  Dimila Mothé  Rafael Costa da Silva  Leonardo dos Santos Avilla 《Journal of South American Earth Sciences》2011,31(2-3):171-177

This study reports implications of different tooth marks left by carnivorous mammals on long bones of Haplomastodon waringi from the Quaternary of Águas de Araxá, Minas Gerais, Brazil. Analyses of gnawing damage by ursids, felids, and canids have shown that these groups produce pits on bone surfaces when the gnawing is superficial, and punctures more often when the prey is intensely consumed. Scratches or scoring marks are most often associated with gnawing by canids, which may spend a long time gnawing the bones, leading to differential tooth marking. The gomphothere bones at Águas de Araxá did not result from predation, but are a consequence of a local mass mortality in a period of low environmental humidity, with little water and a scarcity of food. Canids frequently act as opportunistic scavengers during periods when herbivores face food shortages. Previous studies of necrophagous dermestid larvae indicate that the gomphothere carcasses of Águas de Araxá were exposed for a long period of time after death. These insects are the last consumers of a carcass because they act only when the body fat is completely lost. Thus, the gomphothere carcasses at Águas de Araxá suffered canid necrophagy in the early stages of decomposition, possibly during a drought period. Thereafter, the gomphothere carcasses would have been exposed for a period about 230 days until the final burial event.  相似文献   

Source Characteristics of the 22 January 2003 M w?=?7.5 Tecom��n, Mexico, Earthquake: New Insights     

Luis Quintanar  H��ctor E. Rodr��guez-Lozoya  Roberto Ortega  Juan M. G��mez-Gonz��lez  Tonatiuh Dom��nguez  Clara Javier  Leonardo Alc��ntara  Cecilio J. Rebollar 《Pure and Applied Geophysics》2011,168(8-9):1339-1353

Aftershock locations, source parameters and slip distribution in the coupling zone between the overriding North American and subducted Rivera and Cocos plates were calculated for the 22 January 2003 Tecomán earthquake. Aftershock locations lie north of the El Gordo Graben with a northwest-southeast trend along the coast and superimposed on the rupture areas of the 1932 (M _w?=?8.2) and 1995 (M _w?=?8.0) earthquakes. The Tecomán earthquake ruptured the northwest sector of the Colima gap, however, half of the gap remains unbroken. The aftershock area has a rectangular shape of 42?±?2 by 56?±?2?km with a shallow dip of roughly 12° of the Wadati-Benioff zone. Fault geometry calculated with the Náb??lek (1984) inversion procedure is: (strike, dip, rake)?=?(277°, 27°, 78°). From the teleseimic body wave spectra and assuming a circular fault model, we estimated source duration of 20?±?2?s, a stress drop of 5.4?±?2.5?MPa and a seismic moment of 2.7?±?.7?×?10²⁰?Nm. The spatial slip distribution on the fault plane was estimated using new additional near field strong motion data (54?km from the epicenter). We confirm their main conclusions, however we found four zones of seismic moment release clearly separated. One of them, not well defined before, is located toward the coast down dip. This observation is the result of adding new data in the inversion. We calculated a maximum slip of 3.2?m, a source duration of 30?s and a seismic moment of 1.88?×?10²⁰?Nm.  相似文献   

Altered mayfly distribution due to strong interactions with alien rainbow trout in Andean streams of Patagonia     

Ricardo Javier Albariño  Leonardo Mario Buria 《Limnologica》2011,41(3):220-227

Nesameletidae is a Southern Hemisphere ephemeropteran family with large-bodied nymphs that are swimming grazers, traits that make aquatic invertebrates vulnerable to visual predators. Metamonius anceps is the sole representative of this family in South America and its present known distribution along the Southern Andes is mostly restricted to headwater streams, usually with clear and well-oxygenated waters.We analyzed their spatial distribution in relation to the presence of the exotic predator rainbow trout (Oncorhynchus mykiss), which is the only fish species in many small Andean Patagonia streams. We measured mayfly abundance in the benthos and drift in reaches with and without fish (the latter being reaches upstream of waterfalls that prevent trout access) in three catchments of Nahuel Huapi Lake basin at the Nahuel Huapi National Park, Argentina. We compared nymphal abundance and body size at the habitat scale and at the reach scale, and nymphal presence and body size in trout diet.A multivariate analysis of physical stream features showed that habitat/reaches with and without fish had similar abiotic characteristics. In no fish sites, nymph density ranged between 44 and 180 m⁻² while in fish sites they were 0–3 m⁻². In one stream nymphs drifted mainly during the day and ∼400 indiv. day⁻¹ were estimated to enter the site with fish. However no nymphs were collected drifting 200 m below the waterfall (the reach with fish). Observations on the diet of rainbow trout also supported the ongoing strong interaction between this mayfly and the trout. M. anceps is a highly vulnerable prey as no permanent populations were found in study reaches with the exotic predator established. Our study emphasizes the potential of natural physical barriers to stop invasive fish having access to headwaters allowing them to harbour natural populations of the most trout-susceptible species supporting pristine ecosystem conditions.  相似文献   

Horizontal and Vertical Turbulent Fluxes Forced by a Gravity Wave Event in the Nocturnal Atmospheric Surface Layer Over the Amazon Forest     

Marcelo?ZeriEmail author  Leonardo?D.?A.?Sá 《Boundary-Layer Meteorology》2011,138(3):413-431

A nocturnal gravity wave was detected over a south-western Amazon forest during the Large-Scale Biosphere–Atmosphere experiment in Amazonia (LBA) in the course of the dry-to-wet season campaign on October 2002. The atmospheric surface layer was stably stratified and had low turbulence activity, based on friction velocity values. However, the passage of the wave, an event with a period of about 180–300 s, caused negative turbulent fluxes of carbon dioxide (CO₂) and positive sensible heat fluxes, as measured by the eddy-covariance system at 60 m (≈30 m above the tree tops). The evolution of vertical profiles of air temperature, specific humidity and wind speed during the wave movement revealed that cold and drier air occupied the sub-canopy space while high wind speeds were measured above the vegetation. The analysis of wind speed and scalars high frequency data was performed using the wavelet technique, which enables the decomposition of signals in several frequencies allowed by the data sampling conditions. The results showed that the time series of vertical velocity and air temperature were −90° out of phase during the passage of the wave, implying no direct vertical transport of heat. Similarly, the time series of vertical velocity and CO₂ concentration were 90° out of phase. The wave was not directly associated with vertical fluxes of this variable but the mixing induced by its passage resulted in significant exchanges in smaller scales as measured by the eddy-covariance system. The phase differences between horizontal velocity and both air temperature and CO₂ concentration were, respectively, zero and 180°, implying phase and anti-phase relationships. As a result, the wave contributed to positive horizontal fluxes of heat and negative horizontal fluxes of carbon dioxide. Such results have to be considered in nocturnal boundary-layer surface-atmosphere exchange schemes for modelling purposes.  相似文献   

Structure and dynamics of distinct fish assemblages in three reaches (upper,middle and lower) of an open tropical estuary in Brazil     

Leonardo M. Neves  Tatiana P. Teixeira  Francisco G. Araújo 《Marine Ecology》2011,32(1):115-131

We collected fishes and environmental variables in three zones (upper, middle and lower) of a small open tropical estuary during flood tide. The aim was to test for differences in fish assemblages along a gradient from freshwater to marine waters and to detect any seasonal variation in fishes and environmental variables across these zones. A total of 111 species (18 in the upper, 50 in the middle and 66 in the lower estuary) were recorded, forming three distinct fish assemblages, with the family Eleotridae dominating in the upper, Gerreidae in the middle, and Sciaenidae in the lower estuary. Only two species (Geophagus brasiliensis in the upper and the middle zones, and Eucinostomus argenteus in the middle and the lower zones) composed more than 1% of the total number of individuals in more than a single zone. Short‐term (tidal) changes in salinity in the middle estuary were associated with different assemblages in the three estuarine zones, even in winter, when the differences in salinity are lowest between the middle and the lower zones. Seasonal variation in salinity was irrelevant, except in a protected sidewater lagoon in the middle estuary. Low salinity seasonal change may be related to the lack of seasonal variation in the structure of fish assemblages in all estuarine zones.  相似文献   

Seasonal effects of rainfall on the shallow pyroclastic deposits of the Campania region (southern Italy)   总被引：6，自引：3，他引：3  

Leonardo Cascini  Giuseppe Sorbino  Sabatino Cuomo  Settimio Ferlisi 《Landslides》2014,11(5):779-792

The shallow deposits of unsaturated pyroclastic soils covering the slopes in the Campania region (southern Italy) are systematically affected by various rainfall-induced slope instabilities. The type and triggering of these instabilities depend on several factors, among which in situ soil suction—as an initial condition—and rainfall—as a boundary condition—play a fundamental role. Based on the available database—which includes a comprehensive catalogue of historical data, in situ soil suction measurements and soil laboratory tests along with the results of geomechanical analyses—this paper discusses the relationships among in situ soil suction and rainfall conditions and induced slope instability types. The goal is to reach a better understanding of past events and gain further insight into the analysis and forecasting of future events. In particular, the paper outlines how the season strongly affects the spatial distribution and the type of slope instability likely to develop. For example, erosion phenomena essentially occur at the end of the dry season and originate hyperconcentrated flows while first-time shallow slides prevail in the rainy season and later propagate as debris flows or as debris avalanches.  相似文献   

Radiological characterization of granitoid outcrops and dimension stones of the Variscan Corsica-Sardinia Batholith     

Antonio Puccini  Gerti Xhixha  Stefano Cuccuru  Giacomo Oggiano  Merita Kaçeli Xhixha  Fabio Mantovani  Carlos Rossi Alvarez  Leonardo Casini 《Environmental Earth Sciences》2014,71(1):393-405

This study focuses on the radiological characterization of granitoid outcrops and dimension stones using in situ gamma-ray spectrometry. Extensive measurements were performed on 210 granitoid outcrops of the Corsica-Sardinia Batholith. The large statistical sample allowed us to improve the analysis by considering a log-normal distribution of radioelements and propagating the uncertainties using Monte Carlo method. The activity concentrations of ⁴⁰K, ²²⁶Ra (²³⁸U) and ²³²Th in C-SB area were 1,177 _?304 ⁺⁴⁰⁸ , 60 _?23 ⁺³⁶ and 69 _?25 ⁺³⁸  Bq/kg (at 1σ uncertainty). The median abundance of K, U and Th on the Variscan C-SB was higher than the average values of the upper continental crust and was comparable with Variscan belt. This corresponds to an outdoor absorbed dose rate of 124 _?26 ⁺³³  nGy/h at 1σ uncertainty which is 3σ higher than the population-weighted average absorbed dose rate (60 nGy/h). Seven commercial granites (Rosa Beta, Ghiandone, Giallo San Giacomo, Rosa Cinzia, Grigio Malaga, Bianco Sardo and Grigio Perla) were investigated to characterize their radiological hazard through 147 measurements taken in 73 extractive quarries. All of the commercial granites were categorized as A2 material based on their activity concentration indices, excluding (at the 3σ level) any restriction on their utilization as superficial materials. Rosa Beta, Grigio Malaga, Grigio Perla and Bianco Sardo can also be used as bulk materials as they can be included in the A1 category. In the case of Ghiandone, Giallo San Giacomo and Rosa Cinzia, we are confident of an A1 classification only at the 1σ level.  相似文献   

The imprint of accretion on the UV spectrum of young stellar objects: an X-Shooter view     

Carlo Felice Manara  Leonardo Testi 《Astrophysics and Space Science》2014,354(1):35-39

The evolution of protoplanetary disks is regulated by its interaction with the central forming star. This interaction happens through accretion of matter from the disk onto the star, and its most significant signatures are the continuum excess in the UV part of the spectrum and the presence of various emission lines. With the VLT/X-Shooter spectrograph, the excess emission in the UV due to accretion can being studied simultaneously with the signatures in the visible and in the near-infrared, giving a simultaneous and complete view of this phenomenon. Here we present some results we obtained using observation and modeling of the UV-excess in young forming stars, which are: (1) the determination of stellar and accretion properties in candidate older accreting young stellar objects and (2) the study of the star-disk interaction in the early stages of planetary system evolution in transitional disk systems.  相似文献   

Uncertainty in floodplain delineation: expression of flood hazard and risk in a Gulf Coast watershed     

Jason Christian  Leonardo Duenas‐Osorio  Aarin Teague  Zheng Fang  Philip Bedient 《水文研究》2013,27(19):2774-2784

This paper investigates the development of flood hazard and flood risk delineations that account for uncertainty as improvements to standard floodplain maps for coastal watersheds. Current regulatory floodplain maps for the Gulf Coastal United States present 1% flood hazards as polygon features developed using deterministic, steady‐state models that do not consider data uncertainty or natural variability of input parameters. Using the techniques presented here, a standard binary deterministic floodplain delineation is replaced with a flood inundation map showing the underlying flood hazard structure. Additionally, the hazard uncertainty is further transformed to show flood risk as a spatially distributed probable flood depth using concepts familiar to practicing engineers and software tools accepted and understood by regulators. A case study of the proposed hazard and risk assessment methodology is presented for a Gulf Coast watershed, which suggests that storm duration and stage boundary conditions are important variable parameters, whereas rainfall distribution, storm movement, and roughness coefficients contribute less variability. The floodplain with uncertainty for this coastal watershed showed the highest variability in the tidally influenced reaches and showed little variability in the inland riverine reaches. Additionally, comparison of flood hazard maps to flood risk maps shows that they are not directly correlated, as areas of high hazard do not always represent high risk. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献