Managing bedload sediment in regulated rivers: Examples from California, U.S.A.

1995 ◽  
pp. 165-176 ◽  
Author(s):  
G. Mathias Kondolf
Keyword(s):  
Regulated Rivers ◽  
Bedload Sediment

Monitoring bedload sediment transport in a pre-Alpine river: an experimental method

2017 ◽  
Vol 43 ◽  
pp. 57-63 ◽  
Author(s):  
Monica Papini ◽  
Vladislav Ivov Ivanov ◽  
Davide Brambilla ◽  
Diego Arosio ◽  
Laura Longoni
Keyword(s):  
Sediment Transport ◽  
Experimental Method ◽  
Alpine River ◽  
Bedload Sediment

EFFECT OF BEDLOAD SEDIMENT NATURAL COMPOSITION ON GEOMETRIC AND DINAMIC CHARACTERISTICS OF CHANNEL FORMS

2018 ◽  
pp. 36-39
Author(s):  
N Ikramov ◽  
T Majidov
Keyword(s):  
Research Work ◽  
Laboratory Data ◽  
Hydroelectric Station ◽  
Negative Consequences ◽  
Movement Velocity ◽  
Reservoir Volume ◽  
Pump Station ◽  
Cross Section Area ◽  
Section Area ◽  
Bedload Sediment

The article brings up data on sediment diversity at watercourse bed and on their movement in the form of ridges. The ridge form movement of sediment leads to the reduction of reservoir volume and canal cross section area, which has an effect on their carrying capacity, filling of pump station forechambers and hydroelectric station pressure basins with sediment. The presence of sediment in flow leads to abrasive deterioration of pumps, water motors and pressure pipes and to other negative consequences. Research work tasks on the study of these effects have been examined with the purpose of preventing such negative consequences. On the basis of laboratory data diagrams and relationships were obtained for ridge length, height and movement velocity vs. sediment hydraulic and geometric sizes.

scholarly journals In-stream uptake and retention of C, N and P in a supraglacial stream

2010 ◽  
Vol 51 (56) ◽  
pp. 80-86 ◽  
Author(s):  
Durelle Scott ◽  
Eran Hood ◽  
Michael Nassry
Keyword(s):  
Nutrient Retention ◽  
Flow Paths ◽  
Lower Velocity ◽  
Outlet Glacier ◽  
Glacier Terminus ◽  
Order Of Magnitude ◽  
Bedload Sediment ◽  
Nutrient Injection ◽  
Carbon Processing ◽  
Ice Water

AbstractSupraglacial streams form annually during the melt season, transporting dissolved solutes from the melting ice and snowpack to subglacial flow paths and the glacier terminus. Although nutrient and carbon processing has been documented in other supraglacial environments (cryoconite holes, snowpack), little work has examined the potential for in-stream nutrient retention in supraglacial streams. Here we carried out a solute nutrient injection experiment to quantify NH3+, PO43−and labile dissolved organic carbon (DOC) retention in a supraglacial stream. The experiment was performed on a 100 m stream reach on Mendenhall Glacier, an outlet glacier on the Juneau Icefield, southeastern Alaska, USA. The study stream contained two distinct reaches of equal length. The first reach had a lower velocity (0.04 ms−1) and contained abundant gravel sediment lining the ice–water interface, while the second reach was devoid of bedload sediment and had an order-of-magnitude higher velocity. At the end of the second reach, the stream emptied into a moulin, which is typical of supraglacial streams on this and other temperate glaciers. We found that N and P were transported largely conservatively, although NO3−increased along the reach, suggestive of nitrification. Labile DOC was retained slightly within the stream, although rates were low relative to the travel times observed within the supraglacial stream. Although our findings show that these streams have low processing rates, measurable in-stream nitrification and dissolved organic matter uptake within this biologically unfavorable environment suggests that supraglacial streams with longer residence times and abundant fine substrate have the potential to modify and retain nutrients during transport to the glacier terminus.

scholarly journals Relative Contribution of the Xiaolangdi Dam to Runoff Changes in the Lower Yellow River

Land ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 521
Author(s):  
Qinghe Zhao ◽  
Shengyan Ding ◽  
Xiaoyu Ji ◽  
Zhendong Hong ◽  
Mengwen Lu ◽  
...  
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Sustainable Management ◽  
Yellow River ◽  
Dam Construction ◽  
Regulated Rivers ◽  
Flood Season ◽  
Abrupt Changes ◽  
Runoff Changes ◽  
Seasonal Runoff

Human activities are increasingly recognized as having a critical influence on hydrological processes under the warming of the climate, particularly for dam-regulated rivers. To ensure the sustainable management of water resources, it is important to evaluate how dam construction may affect surface runoff. In this study, using Mann–Kendall tests, the double mass curve method, and the Budyko-based elasticity method, the effects of climate change and human activities on annual and seasonal runoff were quantified for the Yellow River basin from 1961–2018; additionally, effects on runoff were assessed after the construction of the Xiaolangdi Dam (XLD, started operation in 2001) on the Yellow River. Both annual and seasonal runoff decreased over time (p < 0.01), due to the combined effects of climate change and human activities. Abrupt changes in annual, flood season, and non-flood season runoff occurred in 1986, 1989, and 1986, respectively. However, no abrupt changes were seen after the construction of the XLD. Human activities accounted for much of the reduction in runoff, approximately 75–72% annually, 81–86% for the flood season, and 86–90% for the non-flood season. Climate change approximately accounted for the remainder: 18–25% (annually), 14–19% (flood season), and 10–14% (non-flood season). The XLD construction mitigated runoff increases induced by heightened precipitation and reduced potential evapotranspiration during the post-dam period; the XLD accounted for approximately 52% of the runoff reduction both annually and in the non-flood season, and accounted for approximately −32% of the runoff increase in the flood season. In conclusion, this study provides a basic understanding of how dam construction contributes to runoff changes in the context of climate change; this information will be beneficial for the sustainable management of water resources in regulated rivers.

Analytical approach unifying the two-regime scaling for bedload particle motions

2021 ◽  
Author(s):  
Zi Wu ◽  
Arvind Singh ◽  
Efi Foufoula-Georgiou ◽  
Michele Guala ◽  
Xudong Fu ◽  
...  
Keyword(s):  
Travel Time ◽  
Velocity Variation ◽  
Travel Times ◽  
Scaling Exponents ◽  
Time Scaling ◽  
Dispersion Regime ◽  
The Mean ◽  
Bedload Sediment ◽  
Distance Travel ◽  
First Time

&lt;p&gt;Bedload particle hops are defined as successive motions of a particle from start to stop, characterizing one of the most fundamental processes describing bedload sediment transport in rivers. Although two transport regimes have been recently identified for short- and long-hops, respectively &lt;strong&gt;(Wu et al., &lt;em&gt;Water Resour Res&lt;/em&gt;, 2020)&lt;/strong&gt;, there still lacks a theory explaining how the mean hop distance-travel time scaling may extend to cover the phenomenology of bedload particle motions. Here we propose a velocity-variation based formulation, and for the first time, we obtain analytical solution for the mean hop distance-travel time relation valid for the entire range of travel times, which agrees well with the measured data &lt;strong&gt;(Wu et al., &lt;em&gt;J Fluid Mech&lt;/em&gt;, 2021)&lt;/strong&gt;. Regarding travel times, we identify three distinct regimes in terms of different scaling exponents: respectively as ~1.5 for an initial regime and ~5/3 for a transition regime, which define the short-hops; and 1 for the so-called Taylor dispersion regime defining long-hops. The corresponding probability density function of the hop distance is also analytically obtained and experimentally verified.&amp;#160;&lt;/p&gt;

Emerging mitigation measures and strategies are needed for riverine ecology to ensure sustainable hydropeaking production in Norway 

2021 ◽  
Author(s):  
Jo Halvard Halleraker ◽  
Mahmoud S. R. Kenawi ◽  
Jan Henning L’Abée - Lund ◽  
Anders G. Finstad ◽  
Knut Alfredsen
Keyword(s):  
Biological Indicators ◽  
Ecological Impacts ◽  
Mitigation Strategies ◽  
Mitigation Measures ◽  
National Database ◽  
Political Agenda ◽  
Regulated Rivers ◽  
Hydropower Production ◽  
Multiple Pressures ◽  
Environmental Requirements

&lt;p&gt;&lt;strong&gt;Riverine biodiversity&lt;/strong&gt; is threatened with severe degradation from multiple pressures worldwide. One of the key pressures in European rivers are hydromorphological alterations. Rehabilitation of river habitats is accordingly high on the political agenda at the start of UN decade of ecological restoration (2021-2030).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Water storage&lt;/strong&gt; for hydropower production (HP) has severe impacts on aquatic ecology in Norway, with more than 3000 water bodies designated as heavily modified due to hydropower. Norway is the largest hydropower producer in Europe with a huge amount of high head storage schemes. Ca 86 TWh of this is&amp;#160;storage hydropower, which constitutes more than 50% of the total in Europe. This makes Norway a potentially significant supplier of hydropeaking services. Flexible hydropower operations are crucial for EUs Green Deal in balancing electricity from renewable intermittent power generation such as wind and solar.&amp;#160;&lt;/p&gt;&lt;p&gt;Many Norwegian &lt;strong&gt;HP licenses&lt;/strong&gt; were issued before modern environmental requirements evolved. Few are re-licensed with emerging strategies to mitigate hydropeaking. Still, there seems to be a common understanding of relevant mitigation strategies emerging between many large hydropower producers. For example, flow ramping from hydropower tailrace water with direct outlet into fjords or other lake reservoirs may be less environmentally harmful than outlet into riverine habitat.In this study, we have assessed the Norwegian hydropower portfolio of more than 1600 HP facilities constructing a national database focusing on the knowledge base for assessing potential downstream hydropower ecological impacts. The ecological severity of such flow ramping and the restoration/mitigation potential, may depend on;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;About 51 % of the HPs (ca&lt;strong&gt; 80TWh&lt;/strong&gt;) have tailrace into shorter rivers (&lt;1 km) or directly into fjords or lake/reservoirs. Many of the largest HPs are in this category (e.g 50 HP&gt; 500 MW). Close to 800 HP might have downstream impacts on rivers (&gt; 0.5 km; about 49 % of all HP, in total of ca&lt;strong&gt; 56 TWh&lt;/strong&gt;). Probably &lt;strong&gt;&gt; 3 000 km of regulated rivers&lt;/strong&gt; in Norway therefor might need more ecosystem-based mode of HP operation.&amp;#160;&lt;strong&gt;Flow ramping analysis: &lt;/strong&gt;&amp;#160;Ecosystem-based HP operational rules are established in a selection of sustainably managed Norwegian rivers, still with significant baseload production (0.35-0.76 - TWh annual prod). However, eco-friendly mode of operation seems to be rare as our analysis indicate that flow ramping with potential ecological degradation seems widespread in many rivers. Surprisingly, even in many with operational ramping restriction as required mitigation.Our database may be further improved and updated (with e.g. more flow ramping data and biological indicators) and serve as a basis for a national hydropeaking strategy, and hence make more of the Norwegian hydropower portfolio in line with the EUs sustainability taxonomy.&lt;/p&gt;

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