scholarly journals Flow path depth is the main controller of mean base flow transit times in a mountainous catchment

2012 ◽  
Vol 48 (3) ◽  
Author(s):  
Yuko Asano ◽  
Taro Uchida
Keyword(s):  
Flow Path ◽  
Base Flow ◽  
Mountainous Catchment ◽  
Transit Times

scholarly journals Importance of vegetation, topography and flow paths for water transit times of base flow in alpine headwater catchments

2013 ◽  
Vol 17 (4) ◽  
pp. 1661-1679 ◽  
Author(s):  
M. H. Mueller ◽  
R. Weingartner ◽  
C. Alewell
Keyword(s):  
Stable Isotope ◽  
Vegetation Cover ◽  
Stream Water ◽  
Mean Transit Time ◽  
Snow Accumulation ◽  
Base Flow ◽  
Swiss Alps ◽  
Flow Paths ◽  
Headwater Catchments ◽  
Transit Times

Abstract. The mean transit time (MTT) of water in a catchment gives information about storage, flow paths, sources of water and thus also about retention and release of solutes in a catchment. To our knowledge there are only a few catchment studies on the influence of vegetation cover changes on base flow MTTs. The main changes in vegetation cover in the Swiss Alps are massive shrub encroachment and forest expansion into formerly open habitats. Four small and relatively steep headwater catchments in the Swiss Alps (Ursern Valley) were investigated to relate different vegetation cover to water transit times. Time series of water stable isotopes were used to calculate MTTs. The high temporal variation of the stable isotope signals in precipitation was strongly dampened in stream base flow samples. MTTs of the four catchments were 70 to 102 weeks. The strong dampening of the stable isotope input signal as well as stream water geochemistry points to deeper flow paths and mixing of waters of different ages at the catchments' outlets. MTTs were neither related to topographic indices nor vegetation cover. The major part of the quickly infiltrating precipitation likely percolates through fractured and partially karstified deeper rock zones, which increases the control of bedrock flow paths on MTT. Snow accumulation and the timing of its melt play an important role for stable isotope dynamics during spring and early summer. We conclude that, in mountainous headwater catchments with relatively shallow soil layers, the hydrogeological and geochemical patterns (i.e. geochemistry, porosity and hydraulic conductivity of rocks) and snow dynamics influence storage, mixing and release of water in a stronger way than vegetation cover or topography do.

Cell flow path influences transit time through striated muscle capillaries

1986 ◽  
Vol 250 (6) ◽  
pp. H899-H907 ◽  
Author(s):  
I. H. Sarelius
Keyword(s):  
Transit Time ◽  
Striated Muscle ◽  
Average Distance ◽  
Flow Path ◽  
Capillary Length ◽  
Capillary Networks ◽  
Transit Times ◽  
Total Cell Population ◽  
Path Lengths ◽  
Flow Variables

Indirect estimates of erythrocyte transit time across capillary beds incorporate two assumptions, that the anatomically defined capillary length correctly describes the functional flow path taken by cells across the network, and that the distribution of perfused flow path lengths does not change during hyperemia. Direct measurements of cell flow paths through capillary networks, cell transit times, and associated blood flow variables, have been made using fluorescent erythrocytes as tracers of the total cell population. Observations were made in cremaster muscles from juvenile or adult anesthetized golden hamsters; these tissues have capillary networks of differing degrees of branching. In the juvenile (more branching) networks, mean functional flow path (Lf) was 351 +/- 6 (SE) micron, about twice the average distance from terminal arteriole to collecting venule (172 +/- 37 microns). In the less branching adult networks, Lf = 438 +/- 9 microns compared with the anatomically defined distance of 372 +/- 33 microns. In both groups, Lf distribution was unchanged during hyperemia produced by 10(-4) M adenosine. Directly measured cell transit times across the networks were longer than expected from previous indirect estimates: means were 3.2 +/- 0.1 s in juveniles and 4.2 +/- 0.2 s in adults, with decreases to 2.2 +/- 0.1 and 2.3 +/- 0.1 s, respectively, in hyperemia.

scholarly journals Dynamic hyporheic and riparian flow path geometry through base flow recession in two headwater mountain stream corridors

2017 ◽  
Vol 53 (5) ◽  
pp. 3988-4003 ◽  
Author(s):  
Adam S. Ward ◽  
Noah M. Schmadel ◽  
Steven M. Wondzell ◽  
Michael N. Gooseff ◽  
Kamini Singha
Keyword(s):  
Flow Path ◽  
Base Flow ◽  
Mountain Stream ◽  
Path Geometry

scholarly journals A porewater-based stable isotope approach for the investigation of subsurface hydrological processes

2012 ◽  
Vol 16 (2) ◽  
pp. 631-640 ◽  
Author(s):  
J. Garvelmann ◽  
C. Külls ◽  
M. Weiler
Keyword(s):  
Stable Isotope ◽  
Pore Water ◽  
Input Signal ◽  
Vertical Movement ◽  
Base Flow ◽  
Topographic Wetness Index ◽  
Flow Paths ◽  
Depth Profiles ◽  
Mountainous Catchment ◽  
Isotope Profile

Abstract. Predicting and understanding subsurface flowpaths is still a crucial issue in hydrological research. We present an experimental approach to reveal present and past subsurface flowpaths of water in the unsaturated and saturated zone. Two hillslopes in a humid mountainous catchment have been investigated. The H2O(liquid) – H2O(vapor) equilibration laser spectroscopy method was used to obtain high resolution δ2H vertical depth profiles of pore water at various points along two fall lines of a pasture hillslope in the southern Black Forest, Germany. The Porewater-based Stable Isotope Profile (PSIP) approach was developed to use the integrated information of several vertical depth profiles of deuterium along transects at the hillslope. Different shapes of depth profiles were observed in relation to hillslope position. The statistical variability (inter-quartile range and standard deviation) of each profile was used to characterize different types of depth profiles. The profiles upslope or with a weak affinity for saturation as indicated by a low topographic wetness index preserve the isotopic input signal by precipitation with a distinct seasonal variability. These observations indicate mainly vertical movement of soil water in the upper part of the hillslope before sampling. The profiles downslope or at locations with a strong affinity for saturation do not show a similar seasonal isotopic signal. The input signal is erased in the foothills and a large proportion of pore water samples are close to the isotopic values of δ2H in streamwater during base flow conditions indicating the importance of the groundwater component in the catchment. Near the stream indications for efficient mixing of water from lateral subsurface flow paths with vertical percolation are found.

Intercontinental and transcontinental mail transit times from Europe to Berkeley, 1892 to 1941

1986 ◽  
Vol 13 (2) ◽  
pp. 141-154 ◽  
Author(s):  
RUDOLF SCHMID
Keyword(s):  
Transit Times ◽  
In Transit

SUMMARY Mail transit times from Germany to Berkeley, California, are computed for issues of the current awareness journals Botanisches Centralblatt (1880–1945) and the interdisciplinary Naturae Novitates (1879–1944). Issues of the former for 1892 to 1902 averaged 29.3 days (31.2 days if abnormal times are included) in transit from Kassel to Berkeley, with many issues (92) requiring only 20 to 25 days for intercontinental and transcontinental transit. Mail transit of Naturae Novitates from Berlin to Berkeley averaged 40.7 days (42 if abnormal times are included) per issue for 1903 to 1916 and 44 days (51.1 days) per issue for 1922 to 1941 (cumulatively averaging 42 days, or 45.9 days for abnormal times), with some issues in 1906 requiring only 11-12 days for intercontinental and transcontinental transit. A smaller sampling for Nature for 1923 and 1930 gave averages of, respectively, 21.5 and 22.4 days, with a minimum of 14 days in both years. These times are consistent with known transatlantic and transcontinental, ship and rail, mail transit times for these periods, as tabulated from various sources. For perspective, early intercontinental and transcontinental air transit times and pre-1892 intercontinental ship transit times are also tabulated.

Hydrogeological responses in tropical mountainous springs

2019 ◽  
Author(s):  
Ricardo Sánchez-Murillo
Keyword(s):  
Costa Rica ◽  
Isotope Composition ◽  
Central Valley ◽  
Distribution Functions ◽  
Geochemical Composition ◽  
Transit Times ◽  
Management Plans ◽  
Best Fit ◽  
Term Data

This study presents a hydrogeochemical analysis of spring responses (2013-2017) in the tropical mountainous region of the Central Valley of Costa Rica. The isotopic distribution of δ18O and δ2H in rainfall resulted in a highly significant meteoric water line: δ2H = 7.93×δ18O + 10.37 (r2=0.97). Rainfall isotope composition exhibited a strong dependent seasonality. The isotopic variation (δ18O) of two springs within the Barva aquifer was simulated using the FlowPC program to determine mean transit times (MTTs). Exponential-piston and dispersion distribution functions provided the best-fit to the observed isotopic composition at Flores and Sacramento springs, respectively. MTTs corresponded to 1.23±0.03 (Sacramento) and 1.42±0.04 (Flores) years. The greater MTT was represented by a homogeneous geochemical composition at Flores, whereas the smaller MTT at Sacramento is reflected in a more variable geochemical response. The results may be used to enhance modelling efforts in central Costa Rica, whereby scarcity of long-term data limits water resources management plans.

Altering turbulence in compressible base flow using axisymmetric sub-boundary-layer disturbances

AIAA Journal ◽  
2002 ◽  
Vol 40 ◽  
pp. 2217-2224
Author(s):  
C. J. Bourdon ◽  
J. C. Dutton
Keyword(s):  
Boundary Layer ◽  
Base Flow
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