Hydraulic geometry of cohesive channels undergoing base level drop

Vachtman, Dina; Laronne, Jonathan B.

doi:10.1016/j.geomorph.2013.04.039

Cited by 20 publications

(15 citation statements)

References 56 publications

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“…This time independency is also shown in the study of Vachtman and Laronne [27] who report for the same area a temporal discharge stability over two years with almost no variability. Hence, due to the number of measured springs located in the thermally covered area and the temporal discharge stability the IHS data set is more appropriate for further analysis.…”

Section: Comparison Between Own and Ihs In Situ Measured Spring Dischsupporting

confidence: 74%

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Airborne Thermal Data Identifies Groundwater Discharge at the North-Western Coast of the Dead Sea

et al. 2013

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Abstract:A qualitative and quantitative monitoring of groundwater discharge was conducted based on an airborne thermal campaign undertaken along the north-western coast of the Dead Sea in January 2011 to contribute to the relatively scarce information on groundwater discharge to date in the region. The application of airborne thermal data exploits thermal contrasts that exist between discharging groundwater and background sea surface temperatures of the Dead Sea. Using these contrasts, 72 discharge sites were identified from which only 42 were known from previous in situ measurements undertaken at terrestrial springs by the Israel Hydrological Service. Six of these sites represent submarine springs and at a further 24 locations groundwater appears to seep through the sediment. Although the abundance of groundwater seepage sites suggests a significant, but so far unknown groundwater source, the main contribution appears to originate from

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Section: Comparison Between Own and Ihs In Situ Measured Spring Dischsupporting

confidence: 74%

“…As previously stated the bootstrap regression model explains 93% or 59 × 10 6 m 3 ·a −1 of the in situ measured discharge volume [27]. The resulting difference of 7% (4.1 × 10 6 m 3 ·a −1 ) derives from three factors.…”

Section: Limitationmentioning

confidence: 59%

Airborne Thermal Data Identifies Groundwater Discharge at the North-Western Coast of the Dead Sea

et al. 2013

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“…However, rivers with channel boundaries more resistant to erosion are expected to have dissimilar hydraulic geometry relationships (Schumm 1960, Montgomery andGran 2001). Cohesive-bed rivers reveal distinguishable hydraulic geometry exponents that differ from those for alluvial channels (Ebisa Fola and Rennie 2010, Vachtman and Laronne 2013), and as such, emphasize the importance of the substrate in determining channel morphology.…”

Section: Discharge Monitoring Based On Hydraulic Geometrymentioning

confidence: 99%

“…Williams 1978, Dingman andSharma 1997), and was shown to be particularly robust in natural cohesive channels within bankfull flow conditions (Leopold et al 1964, Vachtman andLaronne 2013).…”

Section: Figmentioning

confidence: 99%

“…This trend can be addressed in terms of temporal variability of the properties of the cohesive strata that control their erodibility, where under conditions of a steady rate of sea level lowering and constant discharge, the adjustment of a cohesive channel width is governed by erosion along incising reaches, being limited by the ability of water to entrain material from the channel bed and banks (Vachtman and Laronne 2013). Such a trend also indicates that, given steady channel discharge and base level drop, adjustment of cohesive channels follows a regular pattern.…”

Section: Figmentioning

confidence: 99%

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Remotely sensed estimation of water discharge into the rapidly dwindling Dead Sea

Vachtman

Laronne

2014

Hydrological Sciences Journal

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The Dead Sea is shrinking as its water level drops at the alarming rate of about 1 m year -1 . The Dead Sea is important to the economies of Israel and Jordan due to the extracted minerals (primarily potassium, also magnesium and bromide). It is also central to regional tourism. It is the lowest place on Earth and its endorheic, saline basin attracts international research in various disciplines. Additional to the Lower Jordan River, the discharge of which has been decreased to a small fraction of its original value, fresh to brackish springs are the main source of water to the rapidly dwindling Dead Sea. Although the existence of these springs has been known for decades, until recently estimates of spring water discharge into the Dead Sea were scarce. In this study, we developed a methodology of water discharge estimation for channels incising into a lacustrine bed using remotely sensed data and a single hydraulic geometry variable, water-surface width. Based on calibration of over 400 in situ measurements and simultaneous hydrometric data from aerial images, width-discharge rating curves were established, tested, and found suitable (r 2 = 0.92, p = 0.001) for the estimation of water discharge, with ±5% uncertainty. Furthermore, we used these relationships to estimate retrospectively the temporal changes in water discharge of seven main channels traceable in historical aerial images. The reconstructed trend reveals a major (63%) reduction in average freshwater inflow between 1990 and 2006. Our results maximize the use of watersurface width information from aerial imagery, and suggest applicability to areas experiencing rapid exposure of sea/lake bed and consequent access difficulties in in situ discharge monitoring.Estimation par télédétection du débit en diminution rapide alimentant la mer Morte Résumé La mer Morte se rétrécit du fait que son niveau baisse au rythme alarmant d'environ 1 m an-1. Elle est importante pour l'économie d'Israël et de la Jordanie en raison des minéraux extraits (principalement le potassium, mais aussi le magnésium et le bromure). Elle est également au centre du tourisme régional. C'est l'endroit le plus bas sur Terre et son bassin endoréique salin attire la recherche internationale de diverses disciplines. En plus du cours inférieur du Jourdain, dont le débit a été réduit à une petite fraction de sa valeur d'origine, des sources douces à saumâtres sont la principale source d'eau de la Mer Morte, en diminution rapide. Bien que l'existence de ces sources soit connue depuis des décennies, les estimations du débit des sources alimentant la mer Morte ont été rares jusqu'à récemment. Dans cette étude, nous avons développé une méthodologie d'estimation du débit pour des canaux incisant un lit lacustre à l'aide de données de la télédétection, avec une seule variable de géométrie hydraulique représentant la largeur de la surface d'eau. Sur la base du calage de plus de 400 mesures in situ et de données hydrométriques simultanées à partir d'images aériennes, les courbes de tarage largeur-débit o...

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From straight to deeply incised meandering channels: Slope impact on sinuosity of confined streams

Dente

Lensky

Morin

et al. 2021

Earth Surf Processes Landf

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Meandering channels and valleys are dominant landscape features on Earth. Their morphology and remnants potentially indicate past base-level fluctuations and changing regional slopes. The prevailing presence of meandering segments in lowslope areas somewhat confuses the physically based relationships between slope and channel meandering. This relationship underlies a fundamental debate: do incised sinuous channels actively develop during steepening of a regional slope, or do they inherit the planform of a preexisting sinuous channel through vertical incision? This question was previously explored through reconstructed evolution of meandering rivers, numerical simulations, and controlled, scaled-down laboratory experiments. Here, we study a rare, field-scale set of a dozen adjacent perennial channels, evolving in recent decades in a homogeneous erodible substrate in response to the Dead Sea level fall (> 30 m over 40 years). These channels are fed by perennial springs and have no drainage basin or previous fluvial history; they initiated straight and transformed into incising meandering channels following the emergence of the preexisting lake bathymetry, which resulted in increased channel lengths and regional slopes at different rates for each channel. This field setting allows testing the impact of changing regional slope on the sinuosity of a stream in the following cases: (a) relatively long and low-gradient shelf-like margins, (b) a sharp increase in the basinward gradient at the shelf-slope transition, and (c) gradually steepening slopes. Under a stable and low valley slope, the channels mainly incise vertically, inheriting a preexisting sinuous pattern. When the regional slope steepens, the channels start to meander, accompanying the vertical incision.The highest sinuosity evolved in the steepest channel, which also developed the deepest and widest valley. These results emphasize the amplifying impact of steepening regional slope on sinuosity. This holds when the flow is confined and chute cutoffs are scarce. K E Y W O R D S base-level fall, channel incision, Dead Sea, incised meanders, steepening slope 1 | INTRODUCTION Sinuous channels and valleys are common landscape features on Earth, as well as on other planets and moons (e.g.

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Hydraulic geometry of cohesive channels undergoing base level drop

Cited by 20 publications

References 56 publications

Airborne Thermal Data Identifies Groundwater Discharge at the North-Western Coast of the Dead Sea

Airborne Thermal Data Identifies Groundwater Discharge at the North-Western Coast of the Dead Sea

Remotely sensed estimation of water discharge into the rapidly dwindling Dead Sea

From straight to deeply incised meandering channels: Slope impact on sinuosity of confined streams

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