scholarly journals Short communication: Field data reveal that the transport probability of clasts in Peruvian and Swiss streams mainly depends on the sorting of the grains

2020 ◽  
Vol 8 (3) ◽  
pp. 717-728
Author(s):  
Fritz Schlunegger ◽  
Romain Delunel ◽  
Philippos Garefalakis
Keyword(s):  
Water Discharge ◽  
Swiss Alps ◽  
Coarse Grained ◽  
Shear Stresses ◽  
Material Transport ◽  
Peruvian Andes ◽  
Annual Water ◽  
Annual Water Discharge ◽  
Bed Material ◽  
Annual Discharge

Abstract. We present field observations from coarse-grained streams in the Swiss Alps and the Peruvian Andes to explore the controls on the probability of material entrainment. We calculate shear stress that is expected for a mean annual water discharge and compare these estimates with grain-specific critical shear stresses that we use as thresholds. We find that the probability of material transport largely depends on the sorting of the bed material, expressed by the D96∕D50 ratio, and the reach gradient but not on mean annual discharge. The results of regression analyses additionally suggest that among these variables, the sorting exerts the largest control on the transport probability of grains. Furthermore, because the sorting is significantly correlated neither to reach gradient nor to water discharge, we propose that the granulometric composition of the material represents an independent, yet important control on the motion of clasts in coarse-grained streams.

scholarly journals Short communication: Field data imply that the sorting (<i>D</i><sub>96</sub> / <i>D</i><sub>50</sub> ratios) of gravel bars in coarse-grained streams influences the probability of sediment transport

2020 ◽  
Author(s):  
Fritz Schlunegger ◽  
Romain Delunel ◽  
Philippos Garefalakis
Keyword(s):  
Water Discharge ◽  
Bedload Transport ◽  
Swiss Alps ◽  
Coarse Grained ◽  
Water Runoff ◽  
Shear Stresses ◽  
Sediment Discharge ◽  
Peruvian Andes ◽  
Gravel Bars ◽  
Bed Material

Abstract. Conceptual models suggest that the mobility of fluvial gravel bars is mainly controlled by sediment discharge. Here we present field observations from streams in the Swiss Alps and the Peruvian Andes to document that for a given water runoff, the probability of bedload transport also depends on the sorting of the bed material. We calculate shear stresses that are expected for a mean annual water discharge, and compare these estimates with grain-specific thresholds. We find a positive correlation between the predicted probability of transport and the sorting of the bed material, expressed by the D96 / D50 ratio. These results suggest that besides sediment discharge, the bedload sorting exerts a measurable control on the gravel bar mobility.

scholarly journals Characterization of Chyulu Hills Watershed Ecosystem Services in South-Eastern Kenya

2016 ◽  
Vol 6 (3) ◽  
pp. 65
Author(s):  
John Warui Kiringe ◽  
Francis Mwaura ◽  
Fiesta Warinwa
Keyword(s):  
Ground Water ◽  
Water Discharge ◽  
Water Source ◽  
Water Volume ◽  
Dry Land ◽  
Shallow Wells ◽  
Water Provision ◽  
Annual Water ◽  
Annual Water Discharge

<p class="1Body">Water is an important good provided by watersheds and is critical in sustaining life and socio-economic development. This study evaluated water provision in the Chyulu Hills watershed which is one of the important dry land water catchments in Kenya. Surface water discharge was mainly through rivers and springs with the latter being more prevalent than the former while ground water provision was primarily through boreholes and shallow wells. Springs discharged the highest water volume annually estimated at 128.14million m<sup>3</sup> or 85.14% of all the water discharged in the watershed, with shallow wells and boreholes discharging the least water. For all the springs found in the watershed, Mzima springs discharged the highest water volume estimated at nearly 113.15 million m<sup>3</sup> annually or 88.30% of the water produced by all the springs; and about 75.19% of the water in the entire watershed. Rivers which were active had a total water discharge of about 20.66million m<sup>3</sup> per year, with Kibwezi River discharging 17.59 million m<sup>3</sup> annually or 85.14% of all the water from rivers. Shallow wells were mainly prevalent at Nthongoni and the Makindu, and their annual water discharge was about 16.96million m<sup>3</sup> per year with boreholes contributing 98.87% (approximately 16.76 million m<sup>3</sup>/yr.) of the ground water, and the rest (19,169.92m<sup>3</sup>/yr.) being contributed by shallow wells. The total amount of water discharged in the watershed by the combined water source types was about 150.49 million m3/yr.</p>

ИЗМЕНЧИВОСТЬ ГОДОВОГО СТОКА РЕКИ АЛАЗАНИ (ГАНЫХ)

2021 ◽  
Vol 1 (1) ◽  
pp. 7-19
Author(s):  
Ф.А Иманов ◽  
Г.И. Кордзахия ◽  
И.С Алиева
Keyword(s):  
Water Discharge ◽  
Correlation Coefficients ◽  
Annual Runoff ◽  
Positive Trend ◽  
Runoff Water ◽  
Transboundary River ◽  
Runoff Change ◽  
Annual Water ◽  
Annual Water Discharge ◽  
The Impact

Abstract. The analysis of spatial and temporal regularities of the annual runoff of the transboundary river Alazani (Ganikh), which flows through the territory of Georgia and Azerbaijan, has been carried out. The series on the average annual water discharge of 6 hydrological gauges for the period from 1925 to 2017/2019 was used. It was found that for the researched rivers, the fluctuations of the average annual water discharges are in phase, however, the absence of strict synchronicity in the fluctuations of the annual runoff leads to a decrease in the spatial correlation coefficients. In the studied series of river Alazani (Ganikh) both on the territory of Georgia and Azerbaijan, there is no trend; however, for a number of annual runoff of the Ayrichai River, the main tributary of the r. Alazani (Ganikh), a significant positive trend was revealed. It should be noted that the reason for the nonstationarity is the climate change, the impact of which on runoff has become noticeable in recent decades. It was found that the variance of the second half of the analyzed series increased. The annual runoff of the Alazani (Ganikh) River has changed very little over 1991-2017 / 2019 compared with the period 1961-1990. For the Ayrichai River, the second period is characterized by increased water content. Keywords: River Alazani (Ganikh), Annual runoff, Water discharge, Transboundary river, Runoff change.

scholarly journals Assessing the impacts of climate change on water resources in the Srepok watershed, Central Highland of Vietnam

2017 ◽  
Vol 8 (3) ◽  
pp. 524-534 ◽  
Author(s):  
Nguyen Thi Huyen ◽  
Le Hoang Tu ◽  
Vo Ngoc Quynh Tram ◽  
Duong Ngoc Minh ◽  
Nguyen Duy Liem ◽  
...  
Keyword(s):  
Climate Change ◽  
Economic Development ◽  
Water Resources ◽  
Water Discharge ◽  
Climate Change Scenarios ◽  
The Third ◽  
Central Highland ◽  
Annual Water ◽  
Annual Water Discharge ◽  
Second Period

The Srepok watershed in the Central Highland of Vietnam plays an important role in the economic development of the region. Any harmful effects of climate change on natural resources may cause difficulties for social and economic development in this area. The present study aims to predict and evaluate changes of water resources in the Srepok watershed under the impact of climate change scenarios by using the soil and water assessment tool (SWAT) model. The study used observed weather data from 1990 to 2010 for the first period and climate change scenarios A1B and A2 from 2011 to 2039 for the second period and from 2040 to 2069 for the third period. According to the climate change scenarios of the studied watershed, future minimum and maximum daily average temperature will rise in all climate change scenarios and the amount of annual precipitation will fall in scenario A1B and go up in scenario A2. Based on the simulation results, the annual water discharge in scenario A1B decreased by 11.1% and 1.2% during the second and third periods, respectively, compared with the first. In scenario A2, annual water discharge increased by 2.4% during the second period but decreased by 1.8% during the third period.

scholarly journals SOURCES OF UNCERTAINTY AND PROBLEMS OF INCREASING THE ACCURACY OF FLOW ASSESMENT FOR THE TRANSBOUNDARY NARVA RIVER

2021 ◽  
Vol 1 ◽  
pp. 84-90
Author(s):  
Artem Iukhno ◽  
Tatiana Yakovleva ◽  
Yaroslav Kobears
Keyword(s):  
Russian Federation ◽  
Water Regime ◽  
River Flow ◽  
Water Discharge ◽  
Sources Of Uncertainty ◽  
Seasonal Factors ◽  
The Russian Federation ◽  
The Republic ◽  
Annual Water ◽  
Annual Water Discharge

The water regime of the transboundary Narva River has always been constantly addressed by the hydrometeorological community. For many years, at the interstate level (the Russian Federation and the Republic of Estonia), there has been a discussion about the accuracy of flow assessment and the correctness of the methods applicable for these purposes. In some years, the discrepancies between the estimates of the average annual water discharge obtained by the Estonian and Russian sides reach values of 20-27%. Sustainable, reliable water use requires updating approaches and achieving greater unambiguity in the flow assessment. In the presented article, various sources of uncertainty in the Narva river flow assessment as hydrodynamic, seasonal factors and imperfection of existing methods are considered. 

scholarly journals River linking in India: Downstream impacts on water discharge and suspended sediment transport to deltas

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
Stephanie A. Higgins ◽  
Irina Overeem ◽  
Kimberly G. Rogers ◽  
Evan A. Kalina
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Water Discharge ◽  
Suspended Load ◽  
Trapping Efficiency ◽  
Future Climate Change ◽  
Suspended Sediment Transport ◽  
Delta Front ◽  
Annual Water ◽  
Annual Water Discharge

To expand agricultural production and address water scarcity, India is moving forward with the National River Linking Project (NRLP), which will connect 44 rivers via 9,600 km of canals. Here, we compile the first complete database of proposed NRLP dams, reservoirs and canals, including operating schedules for Himalayan infrastructure. We evaluate potential NRLP-derived changes to mean annual water discharge for 29 rivers and mean monthly water and sediment discharge for six rivers flowing to five major deltas. Sediment rating curves are used to quantify the impacts of changing water discharge within the rivers, and basin-wide trapping efficiency is established for new reservoirs. Given full implementation of the NRLP, we forecast reductions in annual suspended sediment transport to deltas of 40–85% (Mahanadi), 71–99% (Godavari) and 60–97% (Krishna) due to profound reservoir trapping and peak streamflow reductions. The Ganga before its confluence with the Brahmaputra is projected to experience a 39–75% reduction in annual suspended load. The Brahmaputra before its confluence with the Ganga is projected to experience a 9–25% reduction in suspended load, despite losing only 6% of its annual water flow. We calculate a projected corresponding aggradation decrease for the Ganga-Brahmaputra delta from 3.6 to 2.5 mm y–1, which is a large enough change to drive relative sea-level rise at the delta front. At the remaining four deltas, the NRLP will exacerbate current sediment starvation. We reconstruct the annual water transfer volume proposed for the NRLP to be 245 km3 y–1, higher than previous estimates due to the inclusion of along-canal usage. If completed, the NRLP will transform watershed boundaries, with more than half of the land in India contributing a portion of its runoff to a new mouth. These impacts may have profound environmental and public health implications, particularly in the context of future climate change.

scholarly journals Possible threshold controls on sediment grain properties of Peruvian coastal river basins

2017 ◽  
Vol 5 (3) ◽  
pp. 571-583 ◽  
Author(s):  
Camille Litty ◽  
Fritz Schlunegger ◽  
Willem Viveen
Keyword(s):  
Grain Size ◽  
Drainage Basin ◽  
Water Discharge ◽  
Shear Stresses ◽  
Mountain Range ◽  
Large Area ◽  
Peruvian Andes ◽  
Gravel Beds ◽  
Denudation Rates ◽  
Grain Properties

Abstract. To determine possible controls on sediment grain properties, 21 coastal rivers located along the entire western Peruvian margin were analysed. This represents one of the largest grain size dataset that has been collected over a large area. Modern gravel beds were sampled along a north–south transect on the western side of the Peruvian Andes where the rivers cross the tip of the mountain range, and at each site the long a axis and the intermediate b axis of about 500 pebbles were measured. Morphometric properties of each drainage basin, sediment and water discharge, together with flow shear stresses, were determined and compared against measured grain properties. Pebble size data show that the values for the D50 are nearly constant and range between 2 and 3 cm, while the values of the D96 range between 6 and 12 cm. The ratios between the intermediate and the long axis range from 0.67 to 0.74. Linear correlations between all grain size percentiles and water shear stresses, mean basin denudation rates, mean basin slopes and basin sizes are small to non-existent. However, exceptionally large D50 values of 4–6 cm were measured for basins situated between 11–12 and 16–17° S latitude where hillslope gradients are steeper than on average or where mean annual stream flows exceed the average values of the western Peruvian streams by a factor of 2. We suggest that the generally uniform grain size pattern has been perturbed where either mean basin slopes or water fluxes exceed threshold conditions.

scholarly journals Unravelling Climate and Anthropogenic Forcings on the Evolution of Surface Water Resources in Southern France

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3581
Author(s):  
Camille Labrousse ◽  
Wolfgang Ludwig ◽  
Sébastien Pinel ◽  
Mahrez Sadaoui ◽  
Guillaume Lacquement
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Surface Water ◽  
Water Resources ◽  
Water Discharge ◽  
Study Region ◽  
Southern France ◽  
Surface Water Resources ◽  
Annual Water ◽  
Annual Water Discharge

In the Mediterranean, climate change and human pressures are expected to significantly impact the availability of surface water resources. In order to quantify these impacts during the last 60 years (1959–2018), we examined the hydro-climatic and land use change evolution in six coastal river basins of the Gulf of Lion in southern France. By combining observed water discharge, gridded climate, mapped land use and agricultural censuses data, we propose a statistical regression model which successfully reproduces the variability of annual water discharge in all basins. Our results clearly demonstrate that, despite important anthropogenic water withdrawals for irrigation, climate change is the major driver for the detected reduction of water discharge. The model can explain 78–88% of the variability of annual water discharge in the study catchments. It requires only two climatic indices that are solely computed from monthly temperature (T) and precipitation (P) data, thus allowing the estimation of the respective contributions of both parameters in the detected changes. According to our results, the study region experienced on average a warming trend of 1.6 °C during the last 60 years which alone was responsible for a reduction of almost 25% of surface water resources.

Spatio-temporal analysis of the sediment yield and water turbidity at the right-bank tributaries of the Pripyat River within Ukraine

2020 ◽  
Author(s):  
Yuliia Filippova
Keyword(s):  
Sediment Yield ◽  
Sediment Load ◽  
Water Discharge ◽  
Sediment Discharge ◽  
Water Turbidity ◽  
Spatio Temporal ◽  
Annual Water ◽  
Annual Water Discharge ◽  
The Right ◽  
Annual Sediment

&lt;p&gt;Regularities of the river channel processes are closely related to the magnitude and variability of the river load, and the sediment yield, and the sediment yield is one of the principal factors of the riverbed formation. Cycling and dynamics of the sediment yield need to be taken into account when making hydrotechnical calculation, project work and investigating of the riverbed processes. The amount of the river loads, which find their way into the sub-basin of the Pripyat River each year, depends more on the meteorological conditions of the year. That&amp;#8217;s why sediment yield and water turbidity are non-permanent from year to year. Since the rivers of the investigated region belong to different hydrological zones and regions, characterized by the uniqueness of water regime, which is caused by the peculiarities of hydrographic and orographic territory indexes, the content of the sediment yield and the amount are also not the same.&lt;/p&gt;&lt;p&gt;The water turbidity at the right-bank tributaries of the Pripyat River, which flow within the Ukrainian Polesie, is not large. The water turbidity of the Turia, Ubort River and Vyzhivka is especially small. In certain years the concentration of sediment yield can be bigger. Much more suspended particles are observed in the Styr, Sluch, and Horyn, the upper catchments of which are strongly cut and partially covered with easily washable sediments. The biggest annual average water turbidity was recorded on the Ikva River. Within the accumulative lowland in the downstream river sections, the right-bank tributaries of the Pripyat River carry cleaner water than in the upstream section since the part of sediment load of the river is build up on the riverbeds and creeks. It occurs as a result of the slope and speed reducing. However, on some right-bank rivers of Pripyat, which flow down from small local terrain uplands with cover of loamy forest and sandy sediments, water turbidity can be quite large.&lt;/p&gt;&lt;p&gt;The estimation of the spatio-temporal dynamics of the sediment load is accomplished by difference integral curves taking into account an average annual water discharge, maximum annual water discharge and also average annual sediment discharge and the biggest annual sediment discharge during the whole period of investigation of current hydrological posts for the right-bank tributaries of the Pripyat River within Ukraine. The analysis of synchronicity and equiphase condition of these oscillations had made it possible to identify general noticeable opposite orientation of the set of curves to the oscillation curve of general sediment load. Constructed graphs show interdependence of maximum annual water discharge, average annual sediment discharge, maximum annual sediment discharge because the sediment discharge has to react to hydraulic fluctuation in the flow.&lt;/p&gt;

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