Debris flows triggered from non-stationary glacier lake outbursts: the case of the Teztor Lake complex (Northern Tian Shan,Kyrgyzstan)   总被引：1，自引：0，他引：1  

Sergey Aleksandrovich Erokhin  Vitalii Viktorovich Zaginaev  Anna Alexandrovna Meleshko  Virginia Ruiz-Villanueva  Dmitry Aleksandrovich Petrakov  Sergey Semenovich Chernomorets  Karina Saidovna Viskhadzhieva  Olga Valerjevna Tutubalina  Markus Stoffel 《Landslides》2018,15(1):83-98

One of the most far-reaching glacier-related hazards in the Tian Shan Mountains of Kyrgyzstan is glacial lake outburst floods (GLOFs) and related debris flows. An improved understanding of the formation and evolution of glacial lakes and debris flow susceptibility is therefore essential to assess and mitigate potential hazards and risks. Non-stationary glacier lakes may fill periodically and quickly; the potential for them to outburst increases as water volume may change dramatically over very short periods of time. After the outburst or drainage of a lake, the entire process may start again, and thus these non-stationary lakes are of particular importance in the region. In this work, the Teztor lake complex, located in Northern Kyrgyzstan, was selected for the analysis of outburst mechanisms of non-stationary glacial lakes, their formation, as well as the triggering of flows and development of debris flows and floods downstream of the lakes. The different Teztor lakes are filled with water periodically, and according to field observations, they tend to outburst every 9–10 years on average. The most important event in the area dates back to 1953, and another important event occurred on July 31, 2012. Other smaller outbursts have been recorded as well. Our study shows that the recent GLOF in 2012 was caused by a combination of intense precipitation during the days preceding the event and a rapid rise in air temperatures. Analyses of features in the entrainment and depositional zones point to a total debris flow volume of about 200,000 m³, with discharge ranging from 145 to 340 m³ s^?1 and flow velocities between 5 and 7 m s^?1. Results of this study are key for a better design of sound river corridor planning and for the assessment and mitigation of potential GLOF hazards and risks in the region.  相似文献   

Application of weather radar CAPPI data to verify NWP rainfall accumulation data     

José Marcio Bassan  João Eduardo Machado Perea Martins  Shigetoshi Sugahara  Reinaldo Bomfim da Silveira 《Meteorology and Atmospheric Physics》2015,127(6):725-743

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Synthetic scenario generation of monthly streamflows conditioned to the El Niño–Southern Oscillation: application to operation planning of hydrothermal systems     

Treistman  Felipe  Maceira  Maria Elvira Pi&#;eiro  Penna  D&#;bora Dias Jardim  Dam&#;zio  Jorge Machado  Rotunno Filho  Otto Corr&#;a 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(2):331-353

Stochastic Environmental Research and Risk Assessment - The Brazilian Interconnected Power System is hydro dominated and characterized by large reservoirs presenting multi-year regulation...  相似文献   

Newly discovered reefs in the southern Abrolhos Bank,Brazil: Anthropogenic impacts and urgent conservation needs     

E.F. Mazzei  A.A. Bertoncini  H.T. Pinheiro  L.F. Machado  C.C. Vilar  H.C. Guabiroba  T.J.F. Costa  L.S. Bueno  L.N. Santos  R.B. Francini-Filho  M. Hostim-Silva  J.-C. Joyeux 《Marine pollution bulletin》2017,114(1):123-133

The Abrolhos Bank is an area of high ecological, socio-economic importance and harbour the richest and most-extensive coral reefs in the South Atlantic. Here we report the discovery of shallow (12–25 m depth) reef complex with ten large biogenic structures, intermediate between the typical mushroom-shaped pinnacles of the northern Abrolhos Bank (17°–18° S) and the small patch reefs found on the central/southern coast of the Espírito Santo State (19°–20° S). The newly discovered reefs harbour a relatively rich and abundant reef community, with 73 fish and 14 benthic cnidarian species, including endangered and commercially important ones. We discuss on urgent needs of properly mapping and understanding the ecological functioning of this reef system. Information provided here is a baseline for future impact evaluations, particularly considering the recent worst environmental disaster of Brazil from a dam collapse in Doce river that affected the region.  相似文献   

A Mini‐Review of E‐Waste Management in Brazil: Perspectives and Challenges     

Jos Francisco de Oliveira Neto  Maisa Mendona Silva  Simone Machado Santos 《洁净——土壤、空气、水》2019,47(9)

The accelerated production and replacement of new electrical and electronic equipment demonstrates a tendency for the proportional increase in the generation of e‐waste. Developing countries experience similar social and environmental consequences from this trend, which compounds the other challenges associated with the already poor solid waste management in these regions. Moreover, the dangerous composition of some e‐waste amplifies the problems related to managing these materials. This mini‐review presents a brief overview of e‐waste management in Brazil, including technical aspects, scientific studies, and the challenges ahead. With the Brazilian National Policy of Solid Waste already in place, technical and scientific studies endorse measures that range from incorporating the informal recycling sector into the e‐waste management sector to encouraging the expansion of the recycling industry. All such actions, combined with an intensified commitment of electronic equipment manufacturers to reverse logistics, can improve e‐waste management in Brazil.  相似文献   

Drivers of peatland water table dynamics in the central Andes,Bolivia and Peru     

David J. Cooper  Jeremy Sueltenfuss  Eduardo Oyague  Karina Yager  Daniel Slayback  E. Marcelo Cabero Caballero  Jaime Argollo  Bryan G. Mark 《水文研究》2019,33(13):1913-1925

Cushion plant dominated peatlands are key ecosystems in tropical alpine regions of the Andes in South America. The cushion plants have formed peat bodies over thousands of years that fill many valley bottoms, and the forage produced by the plants is critical for native and nonnative domesticated mammals. The sources and flow paths of water supporting these peatlands remain largely unknown. Some studies have suggested that glacier meltwater streams support some peatlands, and that the ongoing loss of glaciers and their meltwaters could lead to the loss or diminishment of peatlands. We analysed the hydrologic regime of 10 peatlands in four mountain regions of Bolivia and Peru using groundwater monitoring. Groundwater levels in peatlands were relatively stable and within 20 cm of the ground surface during the rainy season, and many sites had water tables 40–90 cm below the ground surface in the dry season. Topographic and groundwater elevations in the peatlands demonstrated that the water source of all 10 peatlands was hillslope groundwater flowing from lateral moraines, talus, colluvium, or bedrock aquifers into the peatlands. There was little to no input from streams, whether derived from glacier melt or other sources, and glacier melt could not have recharged the hillslope aquifers supporting peatlands. We measured the stable water isotopes in water samples taken during different seasons, distributed throughout the catchments, and the values are consistent with this interpretation. Our findings indicate that peatlands in the study region are recharged by hillslope groundwater discharge rather than stream water and may not be as vulnerable to glacial decline as other studies have indicated. However, both glaciers and peatlands are susceptible to changing thermal and precipitation regimes that could affect the persistence of peatlands.  相似文献   

Natural protected areas of San Luis Potosí, Mexico: ecological representativeness,risks, and conservation implications across scales     

Leonardo Chapa-Vargas  Karina Monzalvo-Santos 《International journal of geographical information science》2013,27(9):1625-1641

Assessments of the conservation status of natural resources have been conducted at large (i.e., global, continental, and countrywide) extents. Studies at finer scales, however, can yield increased detail needed to identify conservation strategies for smaller scales which can contribute to goals at the larger extents. Our study was conducted at the scale of a single state, San Luis Potosí, in Central Mexico. Although the state harbors great biological diversity, large areas covered by natural vegetation communities have been and continue to be destroyed by land use changes, cattle grazing, and mine-generated pollution. Our purposes were to quantify the proportion of distribution within natural protected areas (NPAs) of land cover classes, soil types, ecoregions, and altitudinal steps. In addition, within individual NPAs, we aimed at assessing risks. We conducted our analysis at the 1:1, 1:250,000, and 1:1,000,000 scales depending on layer availability. Our results show that actions within the state could contribute to federal and global conservation goals by protecting sites of globally imperiled ecosystems (cloud forests and natural grasslands). At a finer scale, we identified that piedmont scrubland, medium and low tropical moist forests, wetlands, and low elevation habitats are rare and/or constitute conservation omissions within the state. Similarly, ecoregions with mesquite, semi-deciduous, and moist tropical thorn forest, wetlands, and low elevations (<1200 m.a.s.l.) are conservation omissions or gaps. Finally, at the smallest scale, risks within some protected areas (PAs) include the presence of agriculture, cattle grazing, and mine tailings from mines dedicated to extraction of Au, Ag, Cu, Pb, and Zn. Therefore, management within these PAs should minimize such risks through identification of the most important conservation zones within the PAs, and implementation of local legislation prohibiting such activities at the immediacies of conservation zones. Approaches like ours within similar administrative units will help identify ecosystems that are vulnerable and not well protected. However, to prioritize conservation action it is also important to consider surrogates such as species from different groups and ecosystems, as well as rarity and complementarity of such surrogates.  相似文献   

500 Years of rainfall variability and extreme hydrological events in southeastern Spain drylands     

M.J. Machado  G. Benito  M. Barriendos  F.S. Rodrigo 《Journal of Arid Environments》2011,75(12):1244-1253

The semiarid SE fringe of the Iberian Peninsula is considered one of the most sensitive to extreme floods and droughts in the western Mediterranean area. The controlling climatic mechanisms are nevertheless difficult to predict and model. A combined documentary-sedimentary-instrumental 500 years comprehensive register of climatic data (rainfall and flooding) was collated for analysing the decadal to centennial scale hydrological response. Wet years are closely linked to the presence of autumn (SON) positive anomalies (e.g. early 18th century). However, continuous, decadal wet periods seem to correspond in time to both autumn and spring (MAM) positive rainfall anomaly years (e.g. 1570/90, 1830/40, 1870/1900). High frequencies of large floods were registered during the late Medieval Warm Period (AD 950–1200), and during some decades of the Little Ice Age with an average of 0.22 floods/year (1440–1490, 1520–1570, 1600–1740, 1770–1800, 1820–1840, 1870–1900), but flood frequency decreased in the 20th Century (1945–1973; 0.14 floods/year). During wet phases (e.g. late 19th century), large floods occurred during all seasons, whereas a predominantly autumn extreme flooding (>70%) is linked to a rainfall patterns with higher inter-annual variability (e.g. 1945–1973). The recurrence of dry phases is higher since early 17th century, and the frequency of continuous wetter phases lower than the ones with marked annual variability. This results in a trend with less frequent high magnitude catastrophic floods. This study confirms a shift from autumn rainfall maxima towards winter since the early 1990's. The tendency towards longer dry periods and increased inter-annual variability (with 1–3 years maximum wet spells) and a changing seasonal rainfall distribution are thought to be key in modelling projections for this specific arid Mediterranean region.  相似文献   

Distributions of total,inorganic and organic phosphorus in surface and recent sediments of the sub-tropical and semi-pristine Guaratuba Bay estuary,SE Brazil     

Luiz Carlos Cotovicz Junior  Eunice da Costa Machado  Nilva Brandini  Rafaela Cristine Zem  Bastiaan Adriaan Knoppers 《Environmental Earth Sciences》2014,72(2):373-386

This study addresses the distribution of total phosphorus (TP) and its inorganic (IP) and organic (OP) fractions, grain-size and organic matter of surface and recent sediments, coupled to the behavior of total and dissolved inorganic phosphorus (TP and DIP) of the water column, of the semi-pristine Guaratuba Bay estuary, SE Brazil. Surface sediment samples were taken at 43 sites spread along the estuarine gradient and recent sediments from 3 short (35 cm long) cores from the upper, central and lower portions of the estuary, respectively. Highest TP and IP concentrations of surface sediments were detected within the upper sector and the transition zone between the upper and central sectors, all characterized by fine sediments, low salinities and water depths. In contrast, the lower sector and its narrow and deep tidal channel, subject to more intense tidal forcing, exhibited a higher fraction of sandy sediments with lower TP, IP and OP contents. In spite of the spatial variability in sediment grain size, IP corresponded to the major fraction of TP in all estuarine sectors and both TP and IP correlated significantly with the fine sedimentary (silt + clay) grain-size fraction. The fine surface sediments acted as a trap for IP at the fresh water–low salinity interface, which also corresponded to the region of a DIP sink in surface waters. In general, the short sediment cores showed that TP and IP contents increased from 15 cm depths to the top layer. Published sedimentation rates from additional cores taken at the sites of the short cores of this study, implied that depositional alterations of TP and IP increased during the early 1970s, which corresponded to the onset of anthropogenic disturbances from crop plantations in the lowland plains of the river end-member and urbanization at the estuary’s mouth and along the adjacent coast.  相似文献   

The significance of Chara vegetation in the precipitation of lacustrine calcium carbonate     

Mariusz Pełechaty  Andrzej Pukacz  Karina Apolinarska  Aleksandra Pełechata  Marcin Siepak 《Sedimentology》2013,60(4):1017-1035

A significant portion of calcium carbonate is deposited in lake sediments as a result of biological processes related to the photosynthetic activity of phytoplankton in the pelagic realm and, in addition, macrophytes in the littoral zone. Lake Wigry, one of the largest lakes in Poland (north‐east Poland), is characterized by: (i) carbonate sediments with a CaCO₃ content exceeding 80% within the littoral zone; and (ii) large areas of submerged vegetation dominated by charophytes (macroscopic green algae, Characeae family). It is claimed that charophytes are highly effective in utilizing HCO₃^? and forming thick CaCO₃ encrustations. Thus, this study was aimed at evaluating the CaCO₃ production by dense Chara stands overgrowing the lake bottom reaching a depth of 4 m. In late July 2009, the fresh and dry mass of plants, the percentage contribution of calcium carbonate and the production of CaCO₃ per 1 m² were investigated along three transects at three depths (1 m, 2 m and 3 m, with each sample area equal to 0·0625 m²) per transect. The composition and structure of phytoplankton and the physico‐chemical properties of the water analysed in both the littoral and pelagic zones served as the environmental background and demonstrated moderately low fertility in the lake. The greatest dry plant mass exceeded 1000 g m^?2 and CaCO₃ encrustations constituted from 59% to over 76% of the charophyte dry weight. Thus, the maximum and average values of carbonates precipitated by charophytes were 685·5 and 438 g m^?2, respectively, which exceeded previously reported results. A correlation of carbonate production with the depth of Chara stands was detected, and intermediate depths offered the most favourable conditions for carbonate precipitation (589 g m^?2 on average). As precipitated carbonates are ultimately stored in bottom deposits, the results highlight the significance of charophytes in lacustrine CaCO₃ sedimentation.  相似文献