Long-Term Variations of Water Runoff and Suspended Sediment Yield in the Parana and Uruguay Rivers

2018 ◽  
Vol 45 (6) ◽  
pp. 846-860
Author(s):  
M. V. Isupova ◽  
V. N. Mikhailov
2018 ◽  
Vol 55 (1) ◽  
pp. 18-32
Author(s):  
Marit Heideman ◽  
Brian Menounos ◽  
John J. Clague

We use annually laminated lake sediments to estimate suspended sediment yield for a 3850 km2 montane catchment in the British Columbia Coast Mountains. Sediment yield over the past 369 years averages 213 ± 38 Mg·km−2·a−1. Sediment yield increases to 285 ± 50 Mg·km−2·a−1 during the first half of the twentieth century and declines thereafter. The frequency of high-yield events during the 369 year period is irregular: 11 of the 34 events occur in the early part of the twentieth century, a time when glaciers in the watershed underwent major retreat. We fitted a generalized extreme value (GEV) model to estimate quantiles of the sediment yield distribution, and we used epoch analysis to examine persistence in sediment yield following 34 of the largest events. Persistence is greatest for the most extreme events; it is more variable for events that recur, on average, every 10–25 years. Our results indicate that sediment yield is linked to long-term changes in sediment supply to the lake. The results of this study extend earlier sediment yield estimates and improve understanding of linkages to watershed geomorphology, recent glacier retreat, and landslides in the Lillooet River watershed.


Author(s):  
Ludmila V. Kuksina

Abstract. Key factors of sediment yield formation and variability in the Kamchatsky Krai are relief characteristics and climate (especially precipitation). The last research in climate change in Kamchatka demonstrates climate warming – mean annual air temperature has increased on 1.5 ∘C during the period from 1951 to 2009 in average (the maximum increase was revealed in the west of Kamchatka and in the Kamchatka River valley, the minimum one – in the extreme south and north). Decrease of annual precipitation was observed at the same period. In addition frequency and intensity of precipitation is growing. Thereby described climate changes in Kamchatka influence on sediment yield characteristics directly (influence of precipitation on surface washout formation) and indirectly (through water runoff and hydrological regime of rivers changes). Analysis of spatio-temporal variability in suspended sediment yield demonstrated decrease since late 1970–early 1980 in the most part of rivers in the Kamchatsky Krai. Revealed fluctuations demonstrate very good coincidence with precipitation amount variability. Decrease of precipitation leads to corresponding diminution of rainfall erosive factor in the territory which is the key factor of suspended sediment yield formation and variability in rivers in the Kamchatsky Krai. The value of reduction varies from 1 % to 45 % and involves decrease of erosion rates in the territory. Thereby climate change influences on suspended sediment yield in multiple-valued way. Income of friable volcanic deposits on the catchment surface is the key factor of suspended sediment yield formation and variability in some river basins under the impact of volcanic eruptions, and in combination with raising precipitation it can lead to catastrophic increase of sediment yield.


Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1451 ◽  
Author(s):  
Ludmila Kuksina

This study investigates the spatial and temporal variability of water runoff and suspended sediment yield in rivers in the Kamchatsky Krai territory (in the Far East of the Russian Federation). It is based on data from 269 monitoring stations for the period of hydrometeorological observations (1930–2015). The representativeness and the homogeneity of data on water runoff and suspended sediment yield was examined. Regions with prescribed limits of specific water discharge (L·s−1·km−2) and suspended sediment concentration (mg·L−1) variability were selected in the Kamchatsky Krai territory. Most rivers in this region are characterized by two relatively long trends in these characteristics that increased from the late 1970s to the early 1980s, followed by a subsequent decline (until 2015). Kamchatsky Krai includes 9 specific water discharge and 18 suspended sediment concentration regions. Hydrometeorological data of three zonal types of water runoff and corresponding suspended sediment concentration distribution were described, and five azonal types of water regime were characterized. One of these types was characterized by a nearly uniform distribution of water runoff within the year, due to the predominance of groundwater feeding source, while the rest of them had mixed feeding. The present study is the first study to describe the water regime of rivers on volcanic flanks in the Kamchatsky Krai.


Author(s):  
L. Kuksina ◽  
N. Alexeevsky

Abstract. Research into the spatial and temporal variability of suspended sediment flux (SSF, t year−1) has been conducted for rivers in the Kamchatka Krai (in the far east of the Russian Federation). The study of long-term fluctuations in SSF was based on difference-integral curve analysis. Most of the rivers in the region are characterized by two relatively long-term trends in SSF; increases from the late 1970s to the early 1980s, followed by a subsequent decline. Kamchatka was divided into regions based on similar conditions of specific suspended sediment yield (SSSY, t km−2 year−1) followed by a determination of the various factors controlling it. New maps of suspended sediment concentration (SSC, mg L−1) and SSSY for Kamchatka also were constructed and, based on this study, there currently appear to be 18 SSC and 13 SSSY regions, as opposed to 4 and 2 regions, respectively, as had been determined in the 1970s. The influence of volcanoes on SSF can be substantial, and can increase up to 5-fold after eruptions; SSC can reach 6∙105 mg L−1 in rivers draining the flanks of volcanoes.


Author(s):  
L. V. Kuksina

The regularities of spatiotemporal variability of suspended sediment yield characteristics were studied. Based on the analysis of difference-integral yield curves, it was found that most of the rivers in Kamchatka krai are characterized by the presence of two relatively long trends in the suspended sediment yield variability: an increase until the end of the 1970s–early 1980s, and its subsequent decrease. This regularity disturbs in rivers under the influence of volcanic eruptions, where the most significant increasing of sediment yield is observed after major eruptions. Existent maps of mean annual suspended sediment concentration and mean annual specific suspended sediment yield were significantly specified (18 instead 4 and 13 instead two zones were marked respectively). The map of grain-size distribution of suspended sediment was compiled (three zones was marked in region under study). Maximum values of mean annual specific suspended sediment yield (more than 500 t km-2 yr-1), suspended sediment concentration (more than 1000 g m-3) and grain-size of sediments are observed in water runoff of volcanic areas. Minimum values of suspended sediment concentration, specific suspended sediment yield, as well as grain-size of sediments characterized the mainland part of the krai.


Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1831 ◽  
Author(s):  
Donatella Pavanelli ◽  
Claudio Cavazza ◽  
Stevo Lavrnić ◽  
Attilio Toscano

Anthropogenic activities, and in particular land use/land cover (LULC) changes, have a considerable effect on rivers’ flow rates and their morphologies. A representative example of those changes and resulting impacts on the fluvial environment is the Reno Mountain Basin (RMB), located in Northern Italy. Characterized by forest exploitation and agricultural production until World War II, today the RMB consists predominantly of meadows, forests and uncultivated land, as a result of agricultural land abandonment. This study focuses on the changes of the Reno river’s morphology since the 1950s, with an objective of analyzing the factors that caused and influenced those changes. The factors considered were LULC changes, the Reno river flow rate and suspended sediment yield, and local climate data (precipitation and temperature). It was concluded that LUCL changes caused some important modifications in the riparian corridor, riverbed size, and river flow rate. A 40–80% reduction in the river bed area was observed, vegetation developed in the riparian buffer strips, and the river channel changed from braided to a single channel. The main causes identified are reductions in the river flow rate and suspended sediment yield (−36% and −38%, respectively), while climate change did not have a significant effect.


2013 ◽  
Vol 17 (11) ◽  
pp. 4641-4657 ◽  
Author(s):  
S. B. Morera ◽  
T. Condom ◽  
P. Vauchel ◽  
J.-L. Guyot ◽  
C. Galvez ◽  
...  

Abstract. Hydro-sedimentology development is a great challenge in Peru due to limited data as well as sparse and confidential information. This study aimed to quantify and to understand the suspended sediment yield from the west-central Andes Mountains and to identify the main erosion-control factors and their relevance. The Tablachaca River (3132 km2) and the Santa River (6815 km2), located in two adjacent Andes catchments, showed similar statistical daily rainfall and discharge variability but large differences in specific suspended-sediment yield (SSY). In order to investigate the main erosion factors, daily water discharge and suspended sediment concentration (SSC) datasets of the Santa and Tablachaca rivers were analysed. Mining activity in specific lithologies was identified as the major factor that controls the high SSY of the Tablachaca (2204 t km2 yr−1), which is four times greater than the Santa's SSY. These results show that the analysis of control factors of regional SSY at the Andes scale should be done carefully. Indeed, spatial data at kilometric scale and also daily water discharge and SSC time series are needed to define the main erosion factors along the entire Andean range.


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