scholarly journals PIRATARIA FLUVIAL NA SERRA DO ESPIGÃO: DIVISÓRIA DOS RIOS URUGUAI E IGUAÇU-AMÉRICA DO SUL

2021 ◽  
pp. 33-45
Author(s):  
MAÍRA ONEDA DAL PAI ◽  
ANDRÉ AUGUSTO SALGADO ◽  
EDUARDO VEDOR DE PAULA
Keyword(s):  
Drainage Basin ◽  
Profile Analysis ◽  
Geographic Location ◽  
River System ◽  
The Other ◽  
Conditioning Factors ◽  
Base Level ◽  
Control Sets ◽  
Stream Capture ◽  
Local Base

Stream capture is a drainage rearrangement where a flux transference occurs and a contribution area from a drainage basin is incorporated to another. It is about expanding a river system over another one, caused by erosive advantage earned by conditioning factors such as lithostructure, pluviometric regime, topographic gradient, and base level. However, in the southern region of Brazil, a rare dynamic of stream piracy was verified between the drainage basins of the Uruguay and Iguazu (Paraná) rivers. Stream captures were observed along the Serra of Espigão, part of the drainage divide between the two basins. Still, it was not possible to identify which basin was advancing over the other. This paper investigated the occurrence of stream captures, identifying which factors are responsible for this atypical stream dynamic. Mapping the stream captures by remote sensing and further validation with fieldwork, it was verified that there is stream piracy for both sides of the drainage divide. Still, it is not clear which basin is behaving more aggressively. A longitudinal profile analysis of the channels involved in the stream captures showed a local control in the drainage network. This control sets a local base level to the Iguazu river tributaries. It indicates the lithostructural limit between two different geological units: the Serra Geral group basalts and the Botucatu formation sandstones. Depending on the geographic location of this base level, channels that drain to the Iguazu (Paraná) river become more aggressive or less aggressive than the ones that drain to the Uruguai basin, and so they capture or lose area for the other basin. Therefore, it is impossible to identify a river basin that exclusively pirates the other, prevailing, in this case, a mutual competition between the Uruguai and Iguazu (Paraná) rivers basins. This fact highlights the significance of local base levels to promote stream capture processes.

Arenig (Lower Ordovician) conodonts and biozonation in the eastern Siljan district, central Sweden

1994 ◽  
Vol 68 (6) ◽  
pp. 1350-1368 ◽  
Author(s):  
Anita M. Löfgren
Keyword(s):  
North America ◽  
The Other ◽  
South Central ◽  
Lower Ordovician ◽  
Conodont Zone ◽  
Local Base ◽  
Reference Section ◽  
Zones And Subzones

Based on biostratigraphic investigations in the eastern Siljan district, central Sweden, and combined with earlier studies at Hunneberg, south-central Sweden, it is shown that the early post-Tremadoc-age Paroistodus proteus conodont Zone can be divided into four successive subzones. These are, in ascending order: the Drepanoistodus aff. D. amoenus Subzone; the Tripodus Subzone; the Paracordylodus gracilis Subzone; and the Oelandodus elongatus-Acodus deltatus deltatus Subzone. The lowermost of the subzones is a concurrent range zone, with its reference section at Storeklev, Hunneberg, and the other three interval zones with the reference section at Sjurberg in the eastern Siljan district. Correlations between these two areas, as well as with the Flåsjö area, Jämtland, the Finngrundet core, and some other areas, are discussed, and it is concluded that the Drepanoistodus aff. D. amoenus Subzone and the Tripodus Subzone together correspond to the Megistaspis (Ekeraspis) armata trilobite Zone, and occur below the Hunnegraptus copiosus graptolite Zone. The Paracordylodus gracilis Subzone is equivalent with the lower part of the Megistaspis (Varvaspis) planilimbata trilobite Zone, and may correspond to the Hunnegraptus copiosus Zone. The uppermost subzone, the Oelandodus elongatus-Acodus deltatus deltatus Subzone, equals the upper part of the M. (V.) planilimbata Zone, and the local base of the Tetragraptus phyllograptoides graptolite Zone is close to the base of this conodont subzone. The last occurrences of T. phyllograptoides are close to the top of this conodont subzone. Also included in the investigation are the uppermost part of the uppermost Tremadoc Paltodus deltifer Zone and the conodont zones overlying the P. proteus Zone in the eastern Siljan district, the Prioniodus elegans Zone and the Oepikodus evae Zone; the latter zone corresponds to the trilobite zones of Megalaspides (M.) dalecarlicus and Megistaspis (Varvaspis) estonica. A few samples from the superimposed Baltoniodus triangularis, B. navis, and Paroistodus originalis Zones have been investigated and are described as well. The correlation of these conodont zones and subzones with those of areas outside Baltoscandia, particularly North America, is also discussed.

Credibility in Sustainable Aquaculture Eco-Labeling

2019 ◽  
pp. 81-116
Author(s):  
Hamish van der Ven
Keyword(s):  
Best Practice ◽  
Geographic Location ◽  
Poor Performance ◽  
The Other ◽  
Process Tracing ◽  
Direct Result ◽  
Sustainable Aquaculture ◽  
Origin And Evolution ◽  
Domestic Markets ◽  
Comparative Case Studies

This chapter tests the aiming big hypothesis by tracing the origin and evolution of four eco-labeling organizations in sustainable aquaculture: the Aquaculture Stewardship Council (ASC), Best Aquaculture Practices (BAP), Friend of the Sea (FOS), and Naturland. The chapter argues that stronger adherence to best practices in the ASC and BAP programs is a direct result of their decision to target large multinational retailers for certification. Conversely, the comparatively poor performance of the other two eco-labeling organizations can be traced to their decisions to target smaller firms in domestic markets. The chapter uses comparative case studies and within-case process tracing to reveal how decisions about who to target for certification impacted best practice adherence through the causal mechanisms outlined in chapter 3. The four cases analyzed in this chapter cast further doubt on alternate theories of credibility, such as the relevance of ownership or geographic location to credibility.

Was There a Pliocene-Pleistocene Fluvial-Lacustrine Connection between Death Valley and the Colorado River?

1995 ◽  
Vol 43 (3) ◽  
pp. 286-296 ◽  
Author(s):  
William J. Brown ◽  
Michael R. Rosen
Keyword(s):  
Colorado River ◽  
Drainage Basin ◽  
River System ◽  
Turn Of The Century ◽  
Death Valley ◽  
Hydrologic Systems ◽  
Dry Lake ◽  
Middle Pliocene ◽  
River Drainage Basin ◽  
Lake Basins

AbstractSince the turn of the century, a Pliocene-Pleistocene connection between the Death Valley-Owens River pluvial system and the Colorado River drainage basin has been frequently postulated. The two most commonly proposed routes involve (1) a southward overflow from the Death Valley Lake system or (2) southward migration of the Mojave River between its present course and a more southerly route. Under the present topographic regime, a Death Valley Lake capable of overflowing the bedrock saddle at Ludlow, California and discharging southward into the Bristol, Cadiz, and Danby Lake basins (and eventually the Colorado River) would be over 12,000 km2 in size. Few surface and subsurface indicators exist to support either a fluvial or lacustrine connection. Evidence from deep cores and boreholes drilled in Soda, Bristol, Cadiz, and Danby dry lake basins indicate that a hydrologic connection has not occurred during the past 4 myr. No well-documented paleoshoreline features have been located at elevations corresponding to the above hydrologic systems in Death Valley, Silver-Soda, Bristol, or Danby Lake basins. In the Cadiz, Silurian, and Broadwell basins these features have not been found at all. Therefore, we conclude that a hydrologic connection between the Death Valley-Owens River system and the Colorado River has not occurred along either of these routes since the middle Pliocene.

scholarly journals Comparative Analysis of MODIS, MISR and AERONET Climatology over the Middle East and North Africa

2018 ◽  
Author(s):  
Ashraf Farahat
Keyword(s):  
Time Series ◽  
Comparative Analysis ◽  
Middle East ◽  
Biomass Burning ◽  
North Africa ◽  
Geographic Location ◽  
The Other ◽  
Positive Trend ◽  
Data Sampling ◽  
High Dust

Abstract. Comparative analysis of MISR MODIS, and AERONET AOD products performed over seven AERONET stations located in the Middle East and North Africa for the period of 2000–2015. Sites are categorized into dust, biomass burning and mixed. MISR and MODIS AODs agree during high dust seasons but MODIS tends to underestimate AODs during low dust seasons. Over dust dominating sites, MODIS/Terra AOD indicate a negative trend over the time series, while MODIS/Aqua, MISR, and AERONET depict a positive trend. A deviation between MODIS/Aqua and MODIS/Terra was observed regardless of the geographic location and data sampling. The performance of MODIS is similar over all region with ~ 68 % of AODs within the Δτ = ±0.05 ± 0.15τAERO confidence range. MISR AOD retrievals fall within 72 % of the same confidence range for all sites examined here. Both MISR and MODIS capture aerosol climatology; however few cases were observed where one of the two sensors better captures the climatology over a certain location or AOD range than the other sensor.

scholarly journals Variations in the Texture Profile Analysis (TPA) Properties of Clay/Mineral-Medicinal Water Mixtures for Pelotherapy: Effect of Anion Type

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 144 ◽  
Author(s):  
Manuel Pozo ◽  
Francisco Armijo ◽  
Francisco Maraver ◽  
Pilar Zuluaga ◽  
José Ejeda ◽  
...  
Keyword(s):  
Strong Influence ◽  
Profile Analysis ◽  
Salt Lake ◽  
The Other ◽  
Texture Profile ◽  
The Common ◽  
Medicinal Waters ◽  
Intermediate Value ◽  
Anion Type ◽  
Instrumental Texture

A peloid’s liquid phase can be mineral, sea or salt-lake water. This study examines the interactions among three materials, two special clays (bentonite and sepiolite) and one common clay, and three chemically different mineral-medicinal waters. In all clay–water mixtures, the hardness and adhesiveness decreased with the amount of water in the mixture. For a given hardness or adhesiveness, sepiolite retained more water than the other clays, especially in the presence of sulphate-rich mineral-medicinal water (73%). In contrast, the common clay retained the least amount of water (26%), and the bentonite samples returned an intermediate value for the amount of retained water (52–53%). These differences had a strong influence on the thermal behaviour of the mixtures and, hence, should be taken into account for their use in thermotherapy applications. There were no significant differences in the instrumental texture of the clay pastes according to the predominant anion in the mineral-medicinal waters.

scholarly journals River profile response to normal fault growth and linkage: An example from the Hellenic forearc of south-central Crete, Greece

2016 ◽  
Author(s):  
Sean F. Gallen ◽  
Karl W. Wegmann
Keyword(s):  
Drainage Basin ◽  
Profile Analysis ◽  
Normal Fault ◽  
Drainage Area ◽  
Fault System ◽  
Stream Power ◽  
River Incision ◽  
South Central ◽  
History Of ◽  
Fault Growth

Abstract. Topography is a reflection of the tectonic and geodynamic processes that act to uplift the Earth's surface and the erosional processes that work to return it to base level. Numerous studies have shown that topography is a sensitive recorder or tectonic signals. A quasi-physical understanding of the relationship between river incision and rock uplift has made the analysis of fluvial topography a popular technique for deciphering relative, and some argue absolute, histories of rock uplift. Here we present results from a study of the fluvial topography from south-central Crete demonstrating that river longitudinal profiles indeed record the relative history of uplift, but several other processes make it difficult to recover quantitative uplift histories. Prior research demonstrates that the south-central coastline of Crete is bound by a large (~100 km long) E-W striking composite normal fault system. Marine terraces reveal that it is uplifting between 0.1–1.0 mm yr−1. These studies suggest that two normal fault systems, the offshore Ptolemy and onshore South-Central Crete faults linked together in the recent geologic past (Ca. 0.4–1 Myrs bp). Fault mechanics predicts that when adjacent faults link into a single fault the uplift rate in the linkage zone will increase rapidly. Using river profile analysis we show that rivers in south-central Crete record the relative uplift history of fault growth and linkage, as theory predicts that they should. Calibration of the commonly used stream power incision model shows that the slope exponent, n, is ~ 0.5, contrary to most studies that find n ≥ 1. Analysis of fluvial knickpoints shows that migration distances are not proportional to upstream contributing drainage area, as predicted by the stream power incision model. Maps of the transformed stream distance variable, χ, indicate that drainage basin instability, drainage divide migration and river capture events complicate river profile analysis in south-central Crete. Waterfalls are observed in southern Crete and appear to operate under less efficient and different incision mechanics than assumed by the stream power incision model. Drainage area exchange and waterfall formation are argued to obscure linkages between empirically derived metrics and quasi-physical descriptions of river incision, making is difficult to quantitatively interpret rock uplift histories from river profiles in this setting. Karst hydrology, break down of assumed drainage area-discharge scaling and chemical weathering might also contribute to the failure of the stream power incision model to adequately predict the behavior of the fluvial system in south-central Crete.

scholarly journals Towards an understanding of -ward(s) prepositions: a sociohistorical exploration of the distribution of near-identical variants

2016 ◽  
Vol 3 ◽  
Author(s):  
Mary Bisbee
Keyword(s):  
Old English ◽  
The Other ◽  
Conditioning Factors ◽  
Historical Methods

English has a peculiar class of prepositions that exist in two nearly identical forms, one form with a zero ending (-Ø) and the other with an s (-s), all of them containing the Old English suffix -ward. Examples include toward(s), forward(s), onward(s), inward(s), and homeward(s). As language is, by its nature, systematic, it seems unlikely that the occurrence of one form instead of another is totally arbitrary. This project uses sociolinguistic and historical methods to explore some of the conditioning factors in the preference of one form over another, proposing that younger speakers will prefer the zero-ending form as it gradually replaces the other variant, and that the two forms will occur in distinctive environments (phonological, syntactic, or semantic) in issues of media publications. 

scholarly journals Facies association and depositional environment of fan-delta sequence in southwest Kathmandu Basin, Nepal

1970 ◽  
Vol 12 ◽  
pp. 1-16
Author(s):  
Naresh Kazi Tamrakar ◽  
Pramila Shrestha ◽  
Surendra Maharjan
Keyword(s):  
River System ◽  
Sedimentary Facies ◽  
Facies Association ◽  
Base Level ◽  
Rock Types ◽  
Fan Delta ◽  
Main River ◽  
Facies Associations ◽  
Delta Sequence ◽  
The Difference

Lake marginal sedimentation prevailed around the Paleo-Kathmandu Lake. Owing to the difference in local basin conditions; tectonics, source rock types and river systems therein, the lake marginal environments and sedimentary facies associations differ around the Paleo-Kathmandu Lake. In this study, the basin-fill sediments of southwestern margin of the Kathmandu Basin were studied for the sediments recorded in vertical sequences at various localities and facies analysis was made. Mainly eight facies were recognised. They were matrix-supported massive gravel (Gmm), matrix-supported graded gravel (Gmg), gravelly fine or mud (GF), massive silt (Fsm), massive mud (Fm), ripple-laminated silt or laminated silt/mud/clay (Fl), carbonaceous clay (C), and incipient soil with roots (Fr). Four facies associations that were identified were proximal fan-delta facies association (FA1), mid fan-delta facies associaiton (FA2), distal fan-delta facies association (FA3), and gravelly sinuous river facies association (FA4). Remarkably, these facies associations do not contain any sandy facies and foreset bedding of Gilbert-type. The fan-delta region was characterised by flood-dominated flows and vertical accretion of fines in the flood basins, and vegetated swamps rich in organic sediments. The distribution of facies associations suggests extensive lake transgression followed by rapid lake regression. The recent river system then incised the valley against local upliftment due to faulting or lowering of base level of the main river in the Kathmandu Basin probably related to draining out of the lake water. doi: Bulletin of the Department of Geology, Vol. 12, 2009, pp. 1-16

The hydrologic regime of Mackenzie River and connection of "no-closure" lakes to distributary channels in the Mackenzie Delta, Northwest Territories

1995 ◽  
Vol 32 (7) ◽  
pp. 926-937 ◽  
Author(s):  
C. R. Burn
Keyword(s):  
Water Level ◽  
Drainage Basin ◽  
Late Summer ◽  
River System ◽  
Water Levels ◽  
Ice Thickness ◽  
Mackenzie Delta ◽  
Lake Ice ◽  
Discharge System ◽  
Mackenzie River

Mackenzie Delta lakes have been classified by the seasonal duration of their connection to Mackenzie River. "No-closure" lakes are determined on the basis of minimum summer water level. Such lakes may become disconnected from the Mackenzie in autumn or winter, as water level falls or if the sills between lakes and distributary channels are frozen through and so sealed. Water level in the central delta rises continuously after late November–early December, at first because discharge into the delta increases once the Mackenzie drainage basin has frozen over, and then as sea and channel ice thickens in the outer delta, impounding discharge. Since 1973 this seasonal increase in stage from its minimum in early December to the level on 1 April has been between 29 and 95 cm. Between 1987 and 1994, the rise in stage near Inuvik has been slightly greater than increases in lake-ice thickness (30–68 cm). Channels and lakes that are connected to the Mackenzie discharge system in December may remain connected throughout winter. A critical sill elevation for connection of such lakes to the river system is the minimum stage minus mid-December ice thickness. Recently, these elevations have been from 1.0 to 1.6 m lower than late summer water levels. Lakes with sill elevations still lower may remain connected to the Mackenzie throughout the year. In 1993-1994, only 3 of 16 "no-closure" lakes surveyed near Inuvik remained open to the Mackenzie discharge throughout winter, representing 2% of the lakes in this portion of the delta.

separating groundwater response to climate and anthropogenic changes using long-term groundwater head time series in the Netherlands

2020 ◽  
Author(s):  
Willem Zaadnoordijk
Keyword(s):  
Time Series ◽  
The Netherlands ◽  
Land Use Changes ◽  
The Other ◽  
Regime Changes ◽  
Base Level ◽  
Groundwater Head ◽  
Groundwater Response ◽  
Groundwater Regime

<div>A set of time series has been investigated which spans more than 50 years of groundwater head measurements throughout the Netherlands.<br>The relation between the groundwater head and precipitation and evaporation has been established using linear transfer noise modeling. This has been done for each entire series and for parts. The latter to detect base level changes and other groundwater regime changes.</div><div>In addition, trends in the other components of the groundwater heads have been investigated as well as possible non linearities in the groundwater response.</div><div>The link is explored between the trends and regime changes from the time series models on one hand and anthropogenic (land use) changes and climate change on the other hand.</div><div> </div>

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