Post‐fire hydrological response and suspended sediment transport of a terraced Mediterranean catchment          下载免费PDF全文

Julián García‐Comendador  Josep Fortesa  Aleix Calsamiglia  Adolfo Calvo‐Cases  Joan Estrany 《地球表面变化过程与地形》2017,42(14):2254-2265

In July 2013, a wildfire severely affected the western part of the island of Mallorca (Spain). During the first three post‐fire hydrological years, when the window of disturbance tends to be more open, the hydrological and sediment delivery processes and dynamics were assessed in a representative catchment intensively shaped by terracing that covered 37% of its surface area. A nested approach was applied with two gauging stations (covering 1.2 km² and 4.8 km²) built in September 2013 that took continuous measurements of rainfall, water and sediment yield. Average suspended sediment concentration (1503 mg L^?1) and the maximum peak (33 618 mg L^?1) were two orders of magnitude higher than those obtained in non‐burned terraced catchments of Mallorca. This factor may be related to changes in soils and the massive incorporation of ash into the suspended sediment flux during the most extreme post‐fire event; 50 mm of rainfall in 15 min, reaching an erosivity of 2886 MJ mm ha^?1 h^?1. Moreover, hysteretic counter‐clockwise loops were predominant (60%), probably related to the increased sensitivity of the landscape after wildfire perturbation. Though the study period was average in terms of total annual precipitation (even higher in intensities), minimal runoff (2%) and low sediment yield (6.3 t km^?2 y^?1) illustrated how the intrinsic characteristics of the catchment, i.e. calcareous soils, terraces and the application of post‐fire measures, limited the hydrosedimentary response despite the wildfire impact. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Adjustments in channel morphology due to land‐use changes and check dam installation in mountain torrents of Calabria (southern Italy)          下载免费PDF全文

Diego Fortugno  Carolina Boix‐Fayos  Giuseppe Bombino  Pietro Denisi  Juan Manuel Quiñonero Rubio  Vincenzo Tamburino  Demetrio Antonio Zema 《地球表面变化过程与地形》2017,42(14):2469-2483

In Mediterranean semi‐arid conditions, the availability of studies monitoring channel adjustments as a response to reforestation and check dams over representative observation periods, could help develop new management strategies. This investigation is an integrated approach assessing the adjustments of channel morphology in a typical torrent of southern Italy after land‐use changes and check dam construction across a period of about 60 years. A statistical analysis of historical rainfall records, an analysis of land‐use changes in the catchment area and a geomorphological mapping of channel adjustments were carried out and combined with field surveys of bed surface grain‐size over a 5‐km reach including 14 check dams. The analysis of the historical rainfall records showed a slight decrease in the amount and erosivity of precipitation. Mapping of land‐use changes highlighted a general increase of vegetal coverage on the slopes adjacent to the monitored reaches. Together with the check dam network installation, this increase could have induced a reduction in water and sediment supply. The different erosional and depositional forms and adjustments showed a general narrowing between consecutive check dams together with local modifications detected upstream (bed aggradation and cross‐section expansion together with low‐flow realignments) and downstream (local incision) of the installed check dams. Changes in the torrent bends were also detected as a response to erosional and depositional processes with different intensities. The study highlighted: the efficiency of check dams against the disrupting power of intense floods by stabilizing the active channel and the influence of reforestation in increasing hillslope protection from erosion and disconnectivity of water and sediment flows towards the active channel. Only slight management interventions (for instance, the conversion of the existing check dams into open structures) are suggested, in order to mobilize the residual sediment avoiding further generalized incision of the active channel and coast line erosion. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Modélisation glacio-hydrologique et gestion des ressources en eau dans les Andes équatoriennes : l’exemple de Quito     

Jean-Christophe Pouget  David Proaño  Andrea Vera  Marcos Villacís  Thomas Condom  Marisa Escobar 《水文科学杂志》2017,62(3):431-446

La forte croissance socio-économique de Quito a conduit à d’importants projets de transferts interbassins, intensifiant la mobilisation des ressources d’altitude situées dans des zones écologiques sensibles et connaissant une fonte accélérée des glaciers. Afin d’étudier divers scénarios d’évolutions, nous proposons une modélisation du continuum climat/glacier/hydrologie/gestion des ressources en eau. Utilisant l’outil Water Evaluation and Planning (WEAP), nous avons développé : (1) une modélisation hydro-climatologique semi-distribuée avec des données mensuelles homogénéisées par vectorisation régionale ; (2) une modélisation de la production en eau des glaciers et de leur évolution interannuelle ; (3) une modélisation en unités hydrologiques distinguant différentes couvertures de sols ; et (4) une modélisation de la gestion distinguant droits, allocation et usages de l’eau. Nous présentons les résultats du calage hydrologique mensuel (1963–2006), en étudiant particulièrement l’équifinalité de diverses paramétrisations. Nous montrons la souplesse, la robustesse et les limites de la modélisation proposée, contribuant à cerner différentes incertitudes dans l’évaluation de scénarios prospectifs.  相似文献   

Simulation of Microwave Emission from the Magnetic Arch with Growing Millimeter Spectrum     

A.?S.?MorgachevEmail author  Yu.?T.?Tsap  V.?V.?Smirnova  G.?G.?Motorina  S.?A.?Kuznetsov 《Geomagnetism and Aeronomy》2017,57(8):1028-1037

A three-dimensional simulation of the microwave emission of nonthermal electrons within a flare magnetic loop that takes into account the influence of the chromosphere has been carried out. The paper investigates the possibility of the generation of a microwave spectrum (observed for some solar flares) with a maximum in the centimeter wavelength range and a positive slope in the millimeter one under the some distribution of the magnetic field strength and the parameters of the anisotropic nonthermal electrons along the loop. By the example of the event on July 5, 2012, it is shown that nonthermal electrons can be responsible not only for the centimeter bell-shaped emission spectrum generated in the coronal part of the loop but also for the increasing millimeter spectrum generated in the chromosphere.  相似文献   

Upward infiltration–evaporation method to estimate soil hydraulic properties     

C. Peña-Sancho  T.A. Ghezzehei  B. Latorre  C. González-Cebollada  D. Moret-Fernández 《水文科学杂志》2017,62(10):1683-1693

Determination of saturated hydraulic conductivity, K_s, and the van Genuchten water retention curve θ(h) parameters is crucial in evaluating unsaturated soil water flow. The aim of this work is to present a method to estimate K_s, α and n from numerical analysis of an upward infiltration process at saturation (Cap0), with (Cap0 + h) and without (Cap0) an overpressure step (h) at the end of the wetting phase, followed by an evaporation process (Evap). The HYDRUS model as well as a brute-force search method were used for theoretical loam soil parameter estimation. The uniqueness and the accuracy of solutions from the response surfaces, K_s–n, α–n and K_s–α, were evaluated for different scenarios. Numerical experiments showed that only the Cap0 + Evap and Cap0 + h + Evap scenarios were univocally able to estimate the hydraulic properties. The method gave reliable results in sand, loam and clay-loam soils.  相似文献   

Large wood load and transport in a flood-free period within an inter-dam reach: a decade of monitoring the Dyje River,Czech Republic     

Zdeněk Máčka  Ondřej Kinc  Matej Hlavňa  David Hortvík  Lukáš Krejčí  Jana Matulová  Pavel Coufal  Pavel Zahradníček 《地球表面变化过程与地形》2020,45(14):3540-3555

This study examined the large wood (LW) load and transport during the non-flood period (2009–2018) following major floods that occurred in 2002 and 2006 within the inter-dam reach of the Dyje River (Czech–Austrian border). The LW load was examined in 36 river corridor segments scattered within the reach in the 2009–2018 period. Two whole-reach surveys (2011 and 2019) on LW frequency and distribution were conducted, and the export of LW to the downstream reservoir was analysed between June 2013 and December 2018. In the period of non-flood discharges, the recruitment and depletion of LW were highly variable processes in space and time, leading to a considerable change in the total LW quantity. Whereas the total number of LW pieces decreased, the total LW volume increased because of the increasing dimensions of newly recruited pieces. The annual variability in the quantity of newly recruited pieces was better explained by the variation in the maximum annual discharges (y = 41.043ln(x) + 3.2737, R² = 0.5352) than by the variability in the number of days with wind gusts >17.2 m/s (y = 1.5004x + 82.096, R² = 0.118). The land use change with the abandonment of human settlements after World War II and the progressive expansion of forest was the major historical factor driving the increased recruitment of LW to the river corridor. While the 2006 (>100-year RI) flood brought approximately 1,250 LW pieces to the reservoir, the 2013 (1.5-year RI) flood delivered 45 pieces. The long-term average monthly input of LW to the reservoir was 7.7 pieces. The exceptional low-magnitude flood of 2013, which occurred at the beginning of the monitoring period, was shown to be a threshold above which the number of LW pieces that floated to the dam significantly increased. © 2020 John Wiley & Sons, Ltd.  相似文献   

Effect of source-varying input data on erosion potential model performance     

Nevena Dragičević  Barbara Karleuša  Nevenka Ožanić  Ivica Kisić 《国际地球制图》2019,34(10):1109-1122

This paper examines the performance of the Erosion Potential Method (EPM or Gavrilovi?) and the model response to input data variations caused by choosing different sources of information for the same parameter. The research presented addresses the input data uncertainty via an analysis of the two model input parameters (the soil protection coefficient and the soil erodibility coefficient). The parameter uncertainty analysis is performed following two different approaches: uncertainty analyses of both the selected sample size and the entire population are conducted for an erosion assessment case study of the Dubra?ina River catchment, Croatia. The analysis indicated that, when changing the data source, significant changes in the model outcome values can occur (up to 47% for this case study). Future method modifications should consider the mitigation of these two parameters by potentially making structural changes in the model and therefore moderating the effect.  相似文献   

Food and feeding habits of Octopus insularis in the Veracruz Reef System National Park and confirmation of its presence in the southwest Gulf of Mexico     

Rigoberto Rosas‐Luis  María de Lourdes Jimnez Badillo  Lucia Montoliu‐Elena  Piedad S. Morillo‐Velarde 《Marine Ecology》2019,40(1)

Octopuses are active predators that feed on a wide range of prey including crustaceans, fishes, and mollusks. They are important components of coral reef systems and support local and artisanal fisheries in the Gulf of México. Octopus insularis has been found to be one of the most relevant components in catches from the coral reef system of Veracruz in the southwestern Gulf of Mexico, and its role in the ecosystem requires assessment. To corroborate the morphological identification of O. insularis, six octopuses were identified by genetic methods. And to understand the trophic relationships between this octopus species and its prey, 394 octopuses caught during 2016 and 2017 by an artisanal fleet were sampled and their stomach contents analyzed. Results showed that crustaceans are the most frequently consumed group, with the genera Mithraculus and Etisus being the most important in the diet. Fishes, bivalves, and gastropods were identified as uncommon prey items in the diet. Their presence in the stomachs could be related to the movement of this octopus outside of the coral reef. Considering that our samples were of medium‐ and large‐sized individuals, cannibalism could be discarded for O. insularis in this size range in the Veracruz reef system. These findings suggest a generalist and opportunistic predation of O. insularis on the most abundant and available prey in the study area, namely the crustaceans. These represents an effective transfer of biomass from the low trophic levels to top predators in the coral reef system.  相似文献   

A dendroclimatological study of east- and west-facing slopes in mountainous areas subjected to strong air pollution (the Sudetes,Central Europe)     

Magdalena Opała-Owczarek  Marek Błaś  Mieczysław Sobik  Michał Godek 《自然地理学》2019,40(2):186-208

The Sudetes Mountains (Central Europe) were under a particularly intense long-term air pollution load during the 1970s and 1980s. Intense industrial activity in this area led to large-scale forest dieback and reductions in tree growth rates, potentially limiting the use of tree-ring data from this region in dendroclimatic research. In this paper, ring-width chronologies were constructed for 493 Norway spruce trees (Picea abies L. Karst.) from 17 sampling sites within five major mountain ranges in the Sudetes Mountains of Poland. Growth-climate response data indicate that April?July temperatures are the main factor affecting radial growth of trees in the study area. Our data also indicate the strong influence of slope aspect on temperature signal strength. The lowest correlation values were obtained for sites located on western slopes with effective fog deposition, which are strongly affected by pollution. An appropriate sampling strategy resulted in the creation of a temperature-sensitive proxy record (rAMJJ = 0.70), exceptional for areas under strong pressure from human activity. Based on a regional master chronology, growing season (April?July) temperatures over the past 200 years were then reconstructed. Four warm and four cold periods were distinguished and compared with other reconstructions and long-term instrumental data.  相似文献   

Regional and species specific sexual reproductive patterns of three zooxanthellate scleractinian corals across the Eastern Tropical Pacific          下载免费PDF全文

Jeimy D. Santiago‐Valentín  Susan B. Colley  Peter W. Glynn  Amilcar L. Cupul‐Magaña  Ramon A. López‐Pérez  Fabián A. Rodríguez‐Zaragoza  Francisco Benítez‐Villalobos  Eric Bautista‐Guerrero  Denisse A. Zavala‐Casas  Alma P. Rodríguez‐Troncoso 《Marine Ecology》2018,39(2)

Sexual reproduction of zooxanthellate scleractinian corals in the Eastern Tropical Pacific (ETP) is influenced by the interactive effects of regional and local oceanographic conditions, as well as a variety of other environmental factors. Differences in spatial and temporal gamete development and reproductive patterns of three widespread scleractinian corals of this region—Pocillopora damicornis (branching colony morphology, characterized as hermaphrodite broadcaster), Pavona gigantea (massive colonies, characterized as gonochoric broadcaster/sequential co‐sexually hermaphroditic) and Porites panamensis (encrusting colonies, characterized as gonochoric brooder)—were evaluated at local and regional scales across the ETP. This area extended from the Gulf of California (24°N) to the southern coast of Ecuador (–1°S), including offshore islands, using existing data pooled from prior studies. Predictive models were employed based on environmental variables: sea surface temperature, daylight hours, diffuse attenuation co‐efficient at 490 nm and photosynthetically active radiation. Datasets were extracted from satellite images ( https://oceancolor.gsfc.nasa.gov ) and analysed using WAM_STATIST ver. 6.33® software to obtain monthly average data from each site. The spatial (region, sub‐region and site) and seasonal (wet, dry) variation in reproductive activity (% colonies with gametes) differed among the three species; significant interactions were season × sub‐region for P. damicornis, season × site (sub‐region) for P. gigantea, and season × site for P. panamensis, for which sub‐region was not considered as a factor. The predictive models also suggest that gamete production/maturation of P. damicornis and P. gigantea is influenced by local differences in sea surface temperature and daylight hours. Porites panamensis was not correlated with any environmental variable examined. Variations in local and regional reproductive developmental patterns are likely an acclimatization response by each species imposed by the timing and duration of local stressor events. This analysis has provided insights into the diverse local and regional physical drivers that affect species responses and acclimatization in sexual reproduction across the ETP.  相似文献