Wyniki wyszukiwania - BazTech

1

Quantification of solid particle transport in suspension in a stream : Case of Wadi Zeddine Ain-Defla, Algeria

Bouleknafet Zohir, Elahcene Omar

Journal of Water and Land Development

|

2023

|

no. 56

102--108

EN

Arid and semi-arid areas are characterised by differentiation in meteorological conditions. Sometimes the rains are rare and not very intense and at other times they are dense and very intense, resulting in torrents that often lead to strong soil erosion. Most of the time, the losses occur at the solids level because the erosion effect is too high. In this study, we want to evaluate the transfer of solid sediments as a function of liquid transport in the basin of Wadi Zeddine at Ain Defla in Algeria. To understand this phenomenon, we used the data of liquid flows (Ql, m3∙s-1) and concentration of suspended sediments (C, g∙dm-3), transported in the river, the data collected by the NWRA (National Water Resources Agency), over 24 years have been used to find a relationship between these two quantities, to estimate the quantity of solid transport Qs (kg∙s-1) in the watercourse of the catchment area studied. The results obtained show a good correlation between solid and liquid flows, with a correlation coefficient estimated at 90%, and the average annual sediment supply recorded at the outlet of the Wadi Zeddine watershed is estimated at around 88,048 Mg, which corresponds to 202 Mg∙km-2∙y-1 erosion rate. This value is comparable to those found in other regions with similar hydrological regimes.

2

Short-term dynamics of river water turbidity

Chalov S. R., Tsyplenkov A. S.

Geography and Tourism

|

2018

|

Vol. 6, No. 1

7--14

EN

An overview of the recently collected datasets of highly discrete water turbidity measurements has allowed for the first hydrological and geographical analysis of short-term fluctuations in water turbidity and the composition of suspended sediments. The novel methodology has been developed to estimate a value of TI, which is the ratio of the difference between the maximum and minimum turbidity for a short period of time (ΔTi) (1 hour with the measurement frequency of 20 minutes) and the total turbidity difference for the water regime phase under study (ΔTHE). Higher TI values correspond to a greater contribution of diurnal (20-minute) turbidity fluctuations to the seasonal variability of sediment yield. Rivers have been grouped according to the value of water turbidity fluctuations within one hour (20-minute): glacier-fed rivers (the Tarfala, the Dzhankuat) (TI amounts to 0.17-0.22); volcanic rivers (0.22–0.25) and lowland rivers (the Selenga, the Western Dvina) (0.09).

3

A comparison between the suspended sediment concentrations derived from DELFT3D model and collected using transmissometer – a case study in tidally dominated area of Dithmarschen Bight

Rahbani M.

Oceanologia

|

2015

|

No. 57 (1)

44--49

EN

The objective of this investigation is to verify the deficiencies that incorporate both modelled and measured suspended sediment concentrations (SSC) data in a tidal dominated area. For this purpose a tidal channel, in the North Sea, was considered as the case study. The profiles of SSC from a model were compared with those from the field, in which some dissimilarity was observed. Intensive investigations were carried out to detect that the most discrepancies occur in shallow parts of the area and also during the low velocities. The origin of the shortcomings in regard with the modelling and measuring technique are discussed.

4

Temporal variations of suspended sediment concentration during period of high water stages in the lower course of the Obra River (Western Poland)

Młynarczyk Z., Słowik M.

Archives of Environmental Protection

|

2008

|

Vol. 34, no. 1

33-49

EN

Research concerning temporal variations of suspended sediment concentration during period of high water stages was done in the lower course of the Obra River near Międzyrzecz (Western Poland). The analysis regarding dependence of mean suspended sediment concentration and discharge allowed to determine the way of suspended sediment supply to the river bed during high water stages. It was supposed that exposures of glacial and fluvioglacial sediments in high concave banks could be an important factor influencing the amount of delivery of suspended material. Besides, normal hystcretic loops (oriented clockwise) were observed in cross-sections 4 and 5. That fact would suggest that transported material originates form the Obra River bed or its vicinity. The process of sediment accretion was observed on a fragment of drowned floodplain during high water stages. Collection of samples of freshly deposited sediment and grain size analysis allowed to illustrate the mechanism of forming floodplain sediments. It also was possible to draw near conditions of forming such sediments in the past.

PL

Badania nad zmianami koncentracji materiału zawieszonego w okresie występowania wysokich stanów wody przeprowadzono w dolnym odcinku rzeki Obry, w okolicach Międzyrzecza. Analiza związku pomiędzy średnią koncentracją materiału zawieszonego a przepływem umożliwiła wstępne określenie sposobu dostawy materiału do koryta rzecznego. Ważną rolę mogły tu pełnić odsłonięcia osadów glacjalnych i fluwioglacjalnych znajdujących się w wysokich brzegach wklęsłych koryta Obry. Ponadto na dwóch z pięciu badanych przekrojów pomiarowych zaobserwowano efekt histerezy o przebiegu normalnym, co świadczyłoby o autochtonicznym pochodzeniu transportowanego osadu. Ponadto zaobserwowano proces depozycji osadów na fragmencie równiny zalewowej w okresie występowania wysokich stanów wody. Podjęto w ten sposób próbę przedstawienia mechanizmu tworzenia się litofacji środowiska pozakorytowego. Pozwoliło to na przybliżenie warunków, w jakich osady powodziowe dna doliny Obry były kształtowane w przeszłości.