Combining concentration–discharge relationships with mixing models

2020 ◽  
Author(s):  
Gaëlle Tallec ◽  
José Manuel Tunqui Neira ◽  
Andréassian Vazken ◽  
Jean-Marie Mouchel
Keyword(s):  
River Water ◽  
High Frequency ◽  
Stream Water ◽  
Water Concentration ◽  
Solute Concentration ◽  
Mixing Models ◽  
Stream Discharge ◽  
Factors Influencing ◽  
Flow Components ◽  
Major Factors

<p>Discharge is one of the major factors influencing the evolution of solute concentration in river water. Different modeling approaches exist to characterize the dependency of concentration on discharge: the simplest require calibration, they are based on measurable quantities (stream discharge and stream water concentration) but do not allow for an explicit, physical, flow-path interpretation; the more complex are based on mixing assumptions with different end-member sources, but require knowledge of the (unmeasurable) flow components. Here, we present a combination between the simple concentration–discharge (C-Q) approach with the mass balance (MB) mixing approach, which we apply to a new high-frequency series on the Oracle-Orgeval Observatory (France) (Tunqui et al., submitted). This new methodology shows a better performance than the two approaches applied separately, allowing us to better describe the concentrations measured in the stream.</p><p>Reference : Tunqui et al. Combining concentration-discharge relationships with mixing models. Submitted to Journal of Hydrology</p>

scholarly journals Combined diurnal variations of discharge and hydrochemistry of the Isunnguata Sermia outlet of the Greenland Ice Sheet give in sight on sub glacial conditions

2016 ◽  
Author(s):  
Joseph Graly ◽  
Joel Harrington ◽  
Neil Humphrey
Keyword(s):  
Diurnal Cycle ◽  
Stream Water ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Solute Concentration ◽  
High Flow ◽  
Rock Material ◽  
Diurnal Changes ◽  
Stream Discharge ◽  
Pressure Threshold

Abstract. In order to examine daily cycles in meltwater routing and storage in the Isunnuguata Sermia outlet of the Greenland Ice Sheet, variation in outlet stream discharge and in major element hydrochemistry were assessed over a six day period in July, 2013. Discharge was assessed from hourly photography of the outlet from multiple vantages, including where mid-stream naled ice provided a natural gauge. pH, electrical conductivity, suspended sediment, and alkalinity were measured in samples of stream water collected every three hours. Element and ion concentrations were subsequently measured in a laboratory setting. Photography and stream observations reveal that although river width and stage have only slight diurnal variation, there are large changes in discharge shown in the portion of the width characterized by standing waves and fast flow. Width of this active channel approximately doubles over a diurnal cycle. Together with changes in flow over the naled, these features allow an observationally based relative record of stream discharge in this unconstrained alluvial setting. Peaks in discharge were offset by 3–7 hours from peak melt of the interior ice surface. Concentration of dissolved solutes follows a sinusoidal diurnal cycle, except for large and variable increases in dissolved solutes during the stream’s waning flow. Diurnal changes in solute concentration average 31 % of the base value. Diurnal solute concentration minima and maxima lag peak and minimum stream discharge by 3–6 hours. This phase shift between discharge and solute concentration suggests that during high flow, water is either encountering more rock material or is stored in longer contact with rock material. We suggest that expansion of a distributed subglacial hydrologic network into seldom accessed regions during high flow could account for these phenomena, and for a spike of partial silicate reaction products during waning flow, which itself suggests a pressure threshold-triggered release of stored water.

A comparison of particle breakdown during chewing by guanacos (Lama guanicoe) and sheep

1998 ◽  
Vol 1998 ◽  
pp. 136-136
Author(s):  
M.D. Fraser ◽  
D.H. Baker
Keyword(s):  
Particle Size ◽  
Retention Time ◽  
Microbial Fermentation ◽  
Digestive Efficiency ◽  
Particle Size Reduction ◽  
Lama Guanicoe ◽  
Factors Influencing ◽  
Stomach Motility ◽  
Pass Through ◽  
Major Factors

To date, attempts to account for reported differences in digestive efficiency of camelids and ruminants have focused on factors such as stomach motility and the retention time of feed particles. The physical breakdown of forage into particles small enough to pass through the reticulo-omasal orifice is one of the major factors influencing the rate of passage of digesta from the reticulo-rumen in ruminants. Two of the main processes involved in particle size reduction are chewing (pre- and post-regurgitation) and microbial fermentation. While the characteristic vertical and horizontal jaw movement which occurs during mastication in the camelid is believed to allow for efficient use of the premolars and molars in cutting and grinding fibrous feeds, there have been no comparative studies to verify this, and to assess the contribution of chewing to differences in digestibility coefficients. The aim of this experiment was to directly compare particle breakdown during chewing by guanacos and sheep.

Periodic alterations of the hydrological exchange in hyporheic sediments: colmation, hyporheic fauna and abiotic parameters in a second order stream during one year 

2021 ◽  
Author(s):  
Heide Stein ◽  
Hans Jürgen Hahn
Keyword(s):  
Hyporheic Zone ◽  
Stream Water ◽  
Anthropogenic Activities ◽  
Second Order ◽  
Critical Periods ◽  
Order Stream ◽  
Fine Sediments ◽  
Stream Discharge ◽  
One Year ◽  
Hydrological Exchange

<p>In this study, the temporal variability of the hydrological exchange between stream water (SW) and groundwater (GW), colmation, hyporheic invertebrate fauna, organic matter (OM) and physicochemical parameters were examined for the period of one year. Sampling and measuring were conducted monthly from May 2019 to April 2020 at the Guldenbach river, a second order stream in Rhineland-Palatinate, Germany. All hyporheic samples were extracted from a depth of 15 cm below stream bottom. Colmation was measured quantitatively in the same depth.</p><p>Following the biotic and abiotic patterns found, three temporal stages of different hydrological conditions can be described:</p><ul><li>1) Strong floods, in February and March 2020 caused hydromorphological alterations of the river bed, leading to a decolmation of the hyporheic zone, a wash out of OM and hyporheic fauna. Due to high GW tables the vertical hydrological gradient (VHG) was positive indicating upwelling GW.</li> <li>2) In the months of Mai to August 2019 and April 2020, precipitation and stream discharge were lowest. Predominantly exfiltrating conditions were observed, while the amount of fine sediments (clay and silt) increased as well as colmation. High densities of hyporheic fauna, dominated by fine sediment dwelling taxa, were assessed.</li> <li>3) From September 2019 to January 2020 stream discharge was low. The VHG became increasingly negative, indicating downwelling SW. In accordance, colmation increased continuously, while densities of hyporheic invertebrates decreased and sediment dwellers became more dominant.</li> </ul><p>Precipitation, discharge events and GW table were found to be the driving factors for the annual dynamics of the hydrological exchange as well as for colmation, fauna and hydrochemistry. Electric conductivity seems a suitable indicator for the origin of water with high values in months of low precipitation and lower values after extensive precipitation events, respectively. Hyporheic fauna displayed a significant seasonality and the community structure was correlated with colmation and changes in the VHG.</p><p>This pronounced seasonality seems to be typical of many streams and should be considered for the monitoring of sediments and hyporheic habitats: Seasons with lower stream discharge are probably the most critical periods for sediment conditions.</p><p>We assume that the basic patterns of the dynamics observed basically reflect the natural situation in the catchment. However, the strength of surface run-off and the amount of fine sediments are mainly the result of anthropogenic activities and land use in the catchment.</p><p>These findings underline the significance of dynamical processes for the assessment and implementation of the Water Framework Directive.</p>

scholarly journals A global hotspot for dissolved organic carbon in hypermaritime watersheds of coastal British Columbia

2017 ◽  
Vol 14 (15) ◽  
pp. 3743-3762 ◽  
Author(s):  
Allison A. Oliver ◽  
Suzanne E. Tank ◽  
Ian Giesbrecht ◽  
Maartje C. Korver ◽  
William C. Floyd ◽  
...  
Keyword(s):  
British Columbia ◽  
Organic Matter ◽  
Organic Carbon ◽  
Stream Water ◽  
Coastal Ocean ◽  
Stream Discharge ◽  
Coastal Margin ◽  
Doc Concentration ◽  
Small Catchments ◽  
Dom Composition

Abstract. The perhumid region of the coastal temperate rainforest (CTR) of Pacific North America is one of the wettest places on Earth and contains numerous small catchments that discharge freshwater and high concentrations of dissolved organic carbon (DOC) directly to the coastal ocean. However, empirical data on the flux and composition of DOC exported from these watersheds are scarce. We established monitoring stations at the outlets of seven catchments on Calvert and Hecate islands, British Columbia, which represent the rain-dominated hypermaritime region of the perhumid CTR. Over several years, we measured stream discharge, stream water DOC concentration, and stream water dissolved organic-matter (DOM) composition. Discharge and DOC concentrations were used to calculate DOC fluxes and yields, and DOM composition was characterized using absorbance and fluorescence spectroscopy with parallel factor analysis (PARAFAC). The areal estimate of annual DOC yield in water year 2015 was 33.3 Mg C km−2 yr−1, with individual watersheds ranging from an average of 24.1 to 37.7 Mg C km−2 yr−1. This represents some of the highest DOC yields to be measured at the coastal margin. We observed seasonality in the quantity and composition of exports, with the majority of DOC export occurring during the extended wet period (September–April). Stream flow from catchments reacted quickly to rain inputs, resulting in rapid export of relatively fresh, highly terrestrial-like DOM. DOC concentration and measures of DOM composition were related to stream discharge and stream temperature and correlated with watershed attributes, including the extent of lakes and wetlands, and the thickness of organic and mineral soil horizons. Our discovery of high DOC yields from these small catchments in the CTR is especially compelling as they deliver relatively fresh, highly terrestrial organic matter directly to the coastal ocean. Hypermaritime landscapes are common on the British Columbia coast, suggesting that this coastal margin may play an important role in the regional processing of carbon and in linking terrestrial carbon to marine ecosystems.

Host species influence on flea (Siphonaptera) infection parameters of terrestrial micromammals in a temperate forest of Mexico

Parasitology ◽  
2018 ◽  
Vol 146 (5) ◽  
pp. 670-677
Author(s):  
Fernando Aguilar Montiel ◽  
Arturo Estrada-Torres ◽  
Roxana Acosta ◽  
Miguel Rubio-Godoy ◽  
Jorge Vázquez
Keyword(s):  
Host Species ◽  
National Park ◽  
Temperate Forest ◽  
Flea Species ◽  
Factors Influencing ◽  
La Malinche ◽  
Infection Parameters ◽  
Major Factors ◽  
La Malinche National Park ◽  
Abundance And Distribution

AbstractStudies of abundance and distribution of organisms are fundamental to ecology. The identity of host species is known to be one of the major factors influencing ectoparasitic flea abundance, but explanations are still needed regarding how host taxa influence abundance parameters of different flea species. This study was carried out at La Malinche National Park (LMNP), Tlaxcala, Mexico, where previously 11 flea species had been recorded on 8 host species. Our aims were to list micromammal flea species, to determine flea infection parameters [flea prevalence (FP) and flea mean abundance (FMA)] and to analyse the influence of host species on these parameters. A total of 16 species of fleas were identified from 1178 fleas collected from 14 species of 1274 micromammals captured with Sherman®traps from March 2014 to December 2015 in 18 sites at LMNP. Some host species influence FP and FMA, in particular,Microtus mexicanusandPeromyscus melanotisshowed particularly higher infection values than other host species.Plusaetis aztecusandPlusaetis sibynuswere identified as the most abundant flea species.

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