Debris flow hazard assessment by means of numerical simulations: implications for the Rotolon creek valley (Northern Italy)     

Teresa Salvatici  Stefano Morelli  Veronica Pazzi  William Frodella  Riccardo Fanti 《山地科学学报》2017,14(4):636-648

On 4^th November 2010, a debris flow detached from a large debris cover accumulated above the lowermost portion of the Rotolon landslide (Vicentine Pre-Alps, NE Italy) and channelized in the valley below within the Rotolon Creek riverbed. Such event evolved into a highly mobile and sudden debris flow, damaging some hydraulic works and putting at high risk four villages located along the creek banks. A monitoring campaign was carried out by means of a ground based radar interferometer (GB-InSAR) to evaluate any residual displacement risk in the affected area and in the undisturbed neighbouring materials. Moreover, starting from the current slope condition, a landslide runout numerical modelling was performed by means of DAN-3D code to assess the impacted areas, flow velocity, and deposit distribution of the simulated events. The rheological parameters necessary for an accurate modelling were obtained through the back analysis of the 2010 debris flow event. Back analysis was calibrated with all of the available terrain data coming from field surveys and ancillary documents, such as topographic, geomorphological and geological maps, with pre- and post-event LiDAR derived DTMs, and with orthophotos. Finally, to identify new possible future debris flow source areas as input data for the new modelling, all the obtained terrain data were reanalysed and integrated with the GB-InSAR displacement maps; consequently, new simulations were made to forecast future events. The results show that the integration of the selected modelling technique with ancillary data and radar displacement maps can be a very useful tool for managing problems related to debris flow events in the examined area.  相似文献   

The management challenge posed by marine dispersal of terrestrial plants in coastal dune systems     

Teresa M. Konlechner 《New Zealand geographer》2008,64(2):154-156

Abstract:    Marine dispersal provides a mechanism for introduced plants to invade coastal systems. Regular surveillance is essential for management of marine dispersed weeds. This paper outlines the biological, physical and management dimensions of this coastal issue in New Zealand.  相似文献   

On the contribution of phytoplankton and benthic biofilms to the sediment record of marker pigments in high mountain lakes     

Teresa Buchaca  Jordi Catalan 《Journal of Paleolimnology》2008,40(1):369-383

This study compares the marker pigment composition in three different lake compartments: the water column; the surface sediment biofilm (0–0.5 cm), where production and main degradation processes take place; and the deep sediment (15–17 cm), where the signal is finally stored and marker pigments are used as a proxy in paleolimnological studies. The aim was to evaluate which marker pigments better record in the sediment the relative contributions of planktonic and benthic production in high mountain lakes, taking into account the differential preservation existing among pigments. A survey of 82 high mountain lakes distributed along the major environmental gradients was carried out in the Pyrenees. Comparison of pigments between the three compartments revealed that both water column and sediment biofilm signals could be distinguished in old sediment layers, despite the observation that some of the most characteristic carotenoids that appeared frequently and in high concentrations in the water column were already less common or even absent from the sediment biofilm. In the shallowest lakes, pigment composition in the sediment biofilm was typical of photosynthetically active communities and their deep sediment samples were characterised by a substitution of fucoxanthin by diatoxanthin as the dominant diatom marker pigment. However, in the deepest lakes the pigment composition of the sediment biofilm and deep sediment was similar, characterised by marker pigments of mainly planktonic algal groups and pheophytins, which are typical pigments of decaying communities. Results are discussed in terms of how pigment source (planktonic or benthic) and pigment type (lability of molecule) interact to shape pigment composition in the sediment record of high mountain lakes.  相似文献   

A case study on fuel oil contamination in a mangrove swamp in Hong Kong   总被引：5，自引：0，他引：5  

Tam NF  Wong TW  Wong YS 《Marine pollution bulletin》2005,51(8-12):1092-1100

Mangroves commonly found along tropical and subtropical coastlines are susceptible to oil pollution. In December 2000, around 500 1 m tall Kandelia candel saplings at the age of 3–5 years old located at the foreshore region of Sheung Pak Nai swamp, Hong Kong SAR, were found to be damaged by oil pollution. More than 80% of the saplings were either dead or washed away and leaving less than 5% healthy saplings with dense green leaves. Elevated concentrations of light n-alkanes (ranging from n-C₁₄ to n-C₂₀), pristane and phytane were recorded in surface sediments collected in December 2000. The ratio between light and total n-alkanes was 0.4. The total petroleum hydrocarbons (60–80 μg g⁻¹ TPH) and unresolved complex mixtures (60–70 μg g⁻¹ UCM) were higher than the background values of other mangrove sediments in Hong Kong, which were 40 and 20 μg g⁻¹, respectively. In certain root zone sediments, TPH concentrations were above 1000 μg g⁻¹. These results suggest that surface sediments in Sheung Pak Nai were contaminated by petroleum oil, most likely by illegal discharge of fuel oil which occurred between 1998 and 2002. One year later, in December 2001, unhealthy saplings had recovered and re-grown. The concentrations of TPH and UCM in sediments declined to around 40 μg g⁻¹, pristane and phytane dropped by 80%, and the ratio of light to total n-alkanes was 0.15, suggesting that residual oil in sediments was weathered leading to a remarkable recovery of the unhealthy saplings.  相似文献   

Drying of salt-contaminated masonry: MRI laboratory monitoring     

Teresa Diaz Gonçalves  Leo Pel  José Delgado Rodrigues 《Environmental Geology》2007,52(2):293-302

Drying of masonry specimens was monitored by means of a two-dimensional (2D) magnetic resonance imaging (MRI) technique. The external surfaces stayed wet for longer if NaCl was present instead of pure water only. This corroborates many practical observations that salts aggravate dampness in masonry. A slower evaporation process and not hygroscopicity was the cause. That suggests that salt-induced dampness may, in general, arise simply from changes in the drying process of masonry materials. That also implies that the height and depth at which crystallization occurs in walls may depend on the relative equilibrium humidity (RHeq) and other properties of salts that influence drying of porous materials. Evaporation rates of free surfaces of pure water and saturated NaCl solution were measured by a gravimetric technique. The results indicate that slow drying of salt-contaminated materials is not due only to the lower RHeq of salt solutions. The effective surface of evaporation is likely to be reduced perhaps due to blocking of pores by salt crystals. Final salt-distribution maps of the specimens show that: (a) salts may affect the inner materials of the masonry, even in evaporation-induced processes that lead crystallization to occur predominantly on the external surface; (b) distinct internal distribution patterns occur if masonry composition varies. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.  相似文献   

Rapid characterisation of the extremely large landslide threatening the Rules Reservoir (Southern Spain)     

Reyes-Carmona  Cristina  Galve  Jorge Pedro  Moreno-Sánchez  Marcos  Riquelme  Adrián  Ruano  Patricia  Millares  Agustín  Teixidó  Teresa  Sarro  Roberto  Pérez-Peña  José Vicente  Barra  Anna  Ezquerro  Pablo  López-Vinielles  Juan  Béjar-Pizarro  Marta  Azañón  José Miguel  Monserrat  Oriol  Mateos  Rosa María 《Landslides》2021,18(12):3781-3798

Landslides - When an active landslide is first identified in an artificial reservoir, a comprehensive study has to be quickly conducted to analyse the possible hazard that it may represent to such...  相似文献   

Efficient approach in modeling the shear strength of unsaturated soil using soil water retention curve     

Cavalcante  André Luís Brasil  Mascarenhas  Pedro Victor Serra 《Acta Geotechnica》2021,16(10):3177-3186

Acta Geotechnica - Currently, there are debates on the relationship between the effective stress and shear strength of unsaturated soils. Thus, it is imperative to present an efficient method that...  相似文献   

Multi-stage Ag–Bi–Co–Ni–U and Cu–Bi vein mineralization at Wittichen,Schwarzwald, SW Germany: geological setting,ore mineralogy,and fluid evolution     

Sebastian?Staude  Wolfgang?Werner  Teresa?Mordhorst  Klaus?Wemmer  Dorrit?E.?Jacob  Gregor?MarklEmail author 《Mineralium Deposita》2012,47(3):251-276

The Wittichen Co–Ag–Bi–U mining area (Schwarzwald ore district, SW Germany) hosts several unconformity-related vein-type mineralizations within Variscan leucogranite and Permian to Triassic redbeds. The multistage mineralization formed at the intersection of two fault systems in the last 250 Ma. A Permo-Triassic ore stage I with minor U–Bi–quartz–fluorite mineralization is followed by a Jurassic to Cretaceous ore stage II with the main Ag and Co mineralization consisting of several generations of gangue minerals that host the sub-stages of U–Bi, Bi–Ag, Ni–As–Bi and Co–As–Bi. Important ore minerals are native elements, Co and Ni arsenides, and pitchblende; sulphides are absent. The Miocene ore stage III comprises barite with the Cu–Bi sulfosalts emplectite, wittichenite and aikinite, and the sulphides anilite and djurleite besides native Bi, chalcopyrite, sphalerite, galena and tennantite. The mineral-forming fluid system changed from low salinity (<5 wt.% NaCl) at high temperature (around 300°C) in Permian to highly saline (around 25 wt.% NaCl + CaCl₂) at lower temperatures (50–150°C) in Triassic to Cretaceous times. Thermodynamic calculations and comparison with similar mineralizations worldwide show that the Mesozoic ore-forming fluid was alkaline with redox conditions above the hematite–magnetite buffer. We suggest that the precipitation mechanism for native elements, pitchblende and arsenides is a decrease in pH during fluid mixing processes. REE patterns in fluorite and the occurrence of Bi in all stages suggest a granitic source of some ore-forming elements, whereas, e.g. Ag, Co and Ni probably have been leached from the redbeds. The greater importance of Cu and isotope data indicates that the Miocene ore stage III is more influenced by fluids from the overlying redbeds and limestones than the earlier mineralization stages.  相似文献   

Short- and Long-Term Vegetative Propagation of Two <Emphasis Type="Italic">Spartina</Emphasis> Species on a Salt Marsh in Southern Brazil     

Juliano César Marangoni  César Serra Bonifácio Costa 《Estuaries and Coasts》2012,35(3):763-773

Spartina alterniflora and Spartina densiflora are native salt marsh plants from the Atlantic coast; their habitats in Patos Lagoon estuary (southern Brazil) are characterized by a microtidal regime (<0.5 m) and, during El Niño events, high estuarine water levels and prolonged flooding due to elevated freshwater discharge from a 200,000-km² watershed. During and between El Niño events, the vegetative propagation of these two Spartina species in the largest estuary of southern Brazil (Patos Lagoon) was evaluated by monitoring transplanted plants for 10 years (short-term study) and interpreting aerial photos of natural stands for 56 years (long-term study). During the short-term study, S. alterniflora quickly occupied mud flats (up to 208 cm year^?1) by elongation of rhizomes, whereas S. densiflora showed a modest lateral spread (up to 13 cm year^?1) and generated dense circular-shaped stands. However, moderate and strong El Niño events can promote excessive flooding and positive anomalies in the estuarine water level that reduce the lateral spread and competitive ability of S. densiflora. During the long-term study, natural stands of S. alterniflora and S. densiflora had steady lateral spread rates of 152 and 5.2 cm year^?1, respectively, over mud flats. In the microtidal marshes of the southwest Atlantic, the continuous long-term lateral expansion of both Spartina species embodies periods of intense flooding stress (moderate and strong El Niños), when there is a decrease of vegetative propagation and less stressful low water periods of fast spread over mud flats (non-El Niño periods and weak intensity El Niños).  相似文献   

Badland susceptibility assessment in Volterra municipality (Tuscany,Italy) by means of GIS and statistical analysis     

Silvia Bianchini  Matteo Del Soldato  Lorenzo Solari  Teresa Nolesini  Fabio Pratesi  Sandro Moretti 《Environmental Earth Sciences》2016,75(10):889

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