Hydro‐morphologic Revision of the Cuautla Channel at Nayarit,Mexico     

Cuauhtemoc Franco Ochoa  Edgar Mendoza Baldwin  Rodolfo Silva Casarín  Gabriel Ruiz Martínez 《洁净——土壤、空气、水》2012,40(9):920-925

Pollution, habitat modification, and species migration are some of the results of human activities on natural environments which can be mitigated or compensated with proper planning. Irresponsibility or ignorance in planning coastal projects too often produces damage to natural systems which can be unpredictable and sometimes irrevocable. The specific site analyzed in this paper is the Cuautla littoral sub‐system which was originally a lagoon that diverted river water to other lagoons and estuaries, thus irrigating the Mexican Marismas Nacionales system, in the states of Nayarit and Sinaloa, Mexico. In the 1970s social and economic considerations motivated the construction of a small breaching canal from the sea to the lagoon. The subsequent growth of this channel was unforeseen and has produced an irreversible impact not only in the sub‐system but probably in the entire area of Marismas Nacionales. A lack of understanding of the present balances in the damaged system and of the impacts the changing morphology has on future change has created the need to study this area using numerical hydrodynamic simulation. The present distribution of water in the sub‐system was established and the governing processes were detected. By means of an analytical estimation of equilibrium conditions it was found that if nothing is done, the channel will continue eroding and the ecosystem will continue to degrade. Only by understanding the dramatic perturbations caused by the construction of the channel to the hydrologic and morphologic equilibriums can there be any hope of rescuing the ecosystem, including its human activities.  相似文献   

Characterization of Risks in Coastal Zones: A Review     

Mireille Escudero Castillo  Edgar Mendoza Baldwin  Rodolfo Silva Casarin  Gregorio Posada Vanegas  Maritza Arganis Juaréz 《洁净——土壤、空气、水》2012,40(9):894-905

Interest in sustainable development for the natural, socio‐economic, and cultural resources of coastal zones is growing worldwide. On the other hand, the range of threats to coastal zones increasingly posed by hydro‐meteorological natural phenomena has led to a trend in the analysis and assessment of risks to these areas. The available literature dealing with coastal risk assessment is quite wide, focusing mainly on the risk evaluation of coastal flooding and erosion resulting directly from the occurrence of extreme natural events. The risk assessment methodologies are usually specific to the conditions and available data of each country, society or location, though most have evolved to assess the risk concept more precisely and rigorously. However, there are still very few studies that present feasible and effective methodologies, which lead to the effective integration of risk analysis at all levels. In Mexico coastal risk analysis has barely begun despite our extensive coastline, which is highly vulnerable to the threat of tropical cyclones. This paper aims to give a broad view of the risk assessment methodologies which already exist, in order to provide a starting point for future efforts in Mexico and elsewhere.  相似文献   

Planform dynamics of the Iquitos anabranching structure in the Peruvian Upper Amazon River          下载免费PDF全文

Alejandro Mendoza  Jorge D. Abad  Christian E. Frias  Collin Ortals  Jorge Paredes  Hugo Montoro  Jorge Vizcarra  Cesar Simon  Gabriel Soto‐Cortés 《地球表面变化过程与地形》2016,41(7):961-970

The upper reach of the Amazon River has a very dynamic morphology, with the highest rates of migration observed in the entire Amazon River. It has an anabranching channel pattern which alternates between a condition of single channel and anabranching structures; in particular, the anabranching structure near Iquitos City shows an interesting channel behavior. Its channels migrate at different rates, where there are processes of narrowing and widening, and also collision and development of new channels. The temporal evolution of the Iquitos anabranching structure is described during the period from 1985 to 2014. The study is carried out by using satellite images to track the migration patterns, which are contrasted to the underlying geological units in the valley. Bathymetry of the structure and several velocity transects were obtained during a field campaign prior to the 2012 historic flood event. This information allowed for numerical modeling in order to compute the hydrodynamic flow field that complements the temporal analysis, aiming to understand the planform migration patterns after the 2012 flood event. It is observed that the geological units play an important role in modulating the migration rates and planform development of the channels. The channels in the structure are in contention to be the main channel, which become the secondary channel after migration. This causes the channels to experience a rise in bed elevation and narrowing of the channel itself; if this trend continues for several more years, these channels will detach from the Iquitos anabranching structure, thus forming paleo‐channels. This geomorphic process is important for horizontal and vertical soil heterogeneity along the floodplain. In general, the analysis shows a complex interaction between the underlying geological units, flow structure, morphology of the bed and planform migration. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Development of an electronic seepage chamber for extended use in a river     

Fritz BG  Mendoza DP  Gilmore TJ 《Ground water》2009,47(1):136-140

Seepage chambers have been used to characterize the flux of water across the water-sediment interface in a variety of settings. In this work, an electronic seepage chamber was developed specifically for long-term use in a large river where hydraulic gradient reversals occur frequently with river-stage variations. A bidirectional electronic flowmeter coupled with a seepage chamber was used to measure temporal changes in the magnitude and direction of water flux across the water-sediment interface over an 8-week period. The specific discharge measured from the seepage chamber compared favorably with measurements of vertical hydraulic gradient and previous specific discharge calculations. This, as well as other supporting data, demonstrates the effectiveness of the electronic seepage chamber to accurately quantify water flux in two directions over a multimonth period in this setting. The ability to conduct multimonth measurements of water flux at a subhourly frequency in a river system is a critical capability for a seepage chamber in a system where hydraulic gradients change on a daily and seasonal basis.  相似文献   

High-latitude methane sulphonic acid variability and solar activity: the role of the total solar irradiance     

Blanca Mendoza  Victor Velasco 《Journal of Atmospheric and Solar》2009,71(1):33-40

The direct impact of solar activity on climate has been widely studied through Total Solar Irradiance (TSI). Biological processes also impact climate and are deeply affected by TSI. Marine phytoplankton emissions into the atmosphere have been proposed to change cloud albedo through cloud formation. In this work, we use wavelet analysis to investigate the decadal relation between high-latitude concentrations of methane sulphonic acid, a product of seawater algae, and TSI. We found that some of the methane sulphonic acid main periodicities coincide with periods of solar activity periods.  相似文献   

Diversity of bathyal macrofauna on the northeastern Pacific margin: the influence of methane seeps and oxygen minimum zones     

Lisa A. Levin  Guillermo F. Mendoza  Jennifer P. Gonzalez  rew R. Thurber  & Erik E. Cordes 《Marine Ecology》2010,31(1):94-110

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The Wasatch Environmental Observatory: A mountain to urban research network in the semi-arid western US     

Jennifer J. Follstad Shah  Ryan Bares  Brenda B. Bowen  Gabriel J. Bowen  David R. Bowling  David P. Eiriksson  Benjamin Fasoli  Richard P. Fiorella  Anna Gannet Hallar  Sarah J. Hinners  John D. Horel  Alexander A. Jacques  Logan R. Jamison  John C. Lin  Daniel L. Mendoza  Logan E. Mitchell  Diane E. Pataki  Sarah McKenzie Skiles  Rose M. Smith  Margaret A. Wolf  Paul D. Brooks 《水文研究》2021,35(9):e14352

The 2085 km² Jordan River Basin, and its seven sub-catchments draining the Central Wasatch Range immediately east of Salt Lake City, UT, are home to an array of hydrologic, atmospheric, climatic and chemical research infrastructure that collectively forms the Wasatch Environmental Observatory (WEO). WEO is geographically nested within a wildland to urban land-use gradient and built upon a strong foundation of over a century of discharge and climate records. A 2200 m gradient in elevation results in variable precipitation, temperature and vegetation patterns. Soil and subsurface structure reflect systematic variation in geology from granitic, intrusive to mixed sedimentary clastic across headwater catchments, all draining to the alluvial or colluvial sediments of the former Lake Bonneville. Winter snowfall and spring snowmelt control annual hydroclimate, rapid population growth dominates geographic change in lower elevations and urban gas and particle emissions contribute to episodes of severe air pollution in this closed-basin. Long-term hydroclimate observations across this diverse landscape provide the foundation for an expanding network of infrastructure in both montane and urban landscapes. Current infrastructure supports both basic and applied research in atmospheric chemistry, biogeochemistry, climate, ecology, hydrology, meteorology, resource management and urban redesign that is augmented through strong partnerships with cooperating agencies. These features allow WEO to serve as a unique natural laboratory for addressing research questions facing seasonally snow-covered, semi-arid regions in a rapidly changing world and an excellent facility for providing student education and research training.  相似文献   

Internal shocks in relativistic jets with time-dependent sources     

S. Mendoza  J. C. Hidalgo  D. Olvera  J. I. Cabrera 《Monthly notices of the Royal Astronomical Society》2009,395(3):1403-1408

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Injection of Zero‐Valent Iron into an Unconfined Aquifer Using Shear‐Thinning Fluids     

M.J. Truex  V.R. Vermeul  D.P. Mendoza  B.G. Fritz  R.D. Mackley  M. Oostrom  T.W. Wietsma  T.W. Macbeth 《Ground Water Monitoring & Remediation》2011,31(1):50-58

Approximately 190 kg of 2 μm‐diameter zero‐valent iron (ZVI) particles were injected into a test zone in the top 2 m of an unconfined aquifer within a trichloroethene (TCE) source area. A shear‐thinning fluid was used to enhance ZVI delivery in the subsurface to a radial distance of up to 4 m from a single injection well. The ZVI particles were mixed in‐line with the injection water, shear‐thinning fluid, and a low concentration of surfactant. ZVI was observed at each of the seven monitoring wells within the targeted radius of influence during injection. Additionally, all wells within the targeted zone showed low TCE concentrations and primarily dechlorination products present 44 d after injection. These results suggest that ZVI can be directly injected into an aquifer with shear‐thinning fluids to induce dechlorination and extends the applicability of ZVI to situations where other emplacement methods may not be viable.  相似文献   

Laboratory investigation of pressure gradients induced by plunging breakers     

Adrián Pedrozo-Acuña  Amaia Ruiz de Alegría-Arzaburu  Alec Torres-Freyermuth  Edgar Mendoza  Rodolfo Silva 《Coastal Engineering》2011

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