Dam Sediments Research Articles

Land use effects on sediment yields and soil loss rates in small basins of Triassic sandstone near Sydney, NSW, Australia

Sedimentation surveys of dams in small sandstone drainage basins near Sydney, Australia, demonstrate that land use is the dominant factor determining sediment yields and soil loss rates. Cultivated basins produce an average sediment yield of 7.1 t/ha/year whereas grazed pasture and forest/woodland basins export averages of only 3.3 and 3.1 t/ha/year, respectively. Nevertheless, these yields are high by Australian standards. Sediment exports from grazed pasture and forest/woodland basins are similar because the forest/woodland basins are also grazed. Dam sediments are enriched in clay and organic matter in comparison to topsoils. Gullies and bank erosion are not active geomorphic processes in the drainage basins investigated so that the measured sediment yields could be validly compared to soil loss rates determined by empirical soil loss equations, Modified Universal Soil Loss Equation (MUSLE), Soiloss and Revised Universal Soil Loss Equation (RUSLE), which do not account for gully and channel erosion. These equations accurately predicted the measured sediment yields, with MUSLE being the most accurate. Although Soiloss is the only empirical equation to use Australian data, MUSLE performed marginally better, despite being a simplified version of the Universal Soil Loss Equation (USLE) that is used for teaching. RUSLE predictions of soil loss rates were also closely correlated with measured sediment yields.

The contribution of agricultural erosion to reservoir sedimentation in the Dominican Republic

It is often assumed that the main cause of contemporary erosion and dam sedimentation in tropical watersheds is the cultivation of steep slopes. This study, using fallout 137Cs to estimate net sediment loss since 1963 found erosion in the Nizao watershed of the Dominican Republic to be much lower than often reported for steep tropical hillsides. Because only 17% of the sediment moving into the reservoirs can be attributed to surface agricultural erosion, policies to eliminate upland agriculture will have limited benefits if the principal sources are of natural origin or associated with construction of the dams, and rural roads and trails.

Sediment yields and soil loss rates from native forest, pasture and cultivated land in the Bathurst area, New South Wales

Summary Sedimentation surveys of small dams in granite catchments in the Bathurst area of New South Wales (NSW) demonstrate that land use is the dominant factor determining soil loss rates and sediment yields. We found that cultivated catchments produced, on average, 3.1 t ha−1y−1 whereas grazed pasture and forest/woodland catchments exported only 2.2 and 0.8 t ha−1y−1, respectively. The yields for cultivated and grazed catchments are high by Australian standards. Dam sediments were enriched in clay and organic matter in comparison to catchment topsoils. The dams were deliberately selected so that gully and bank erosion were not active geomorphic processes in the catchments and so the measured sediment yields could be validly compared to soil loss rates predicted by various versions of the Universal Soil Loss Equation. The Modified Universal Soil Loss Equation, Soiloss and Revised Universal Soil Loss Equation did not closely predict the measured sediment yields, as we have found ensewhere in NSW. Although Soiloss is the only empirical equation to use Australian data, it is not as accurate in the Bathurst area as for areas near Sydney. Further research is needed to test and develop soil loss prediction equations under Australian conditions.

豊平川におけるひ素化合物の動態

Mine wastewater and hot spring water flow into the Toyohira River, a source of water for Sapporo City. Since the concentrations of components contained in such water change with the flow regime of the river, water quality management is considered a difficult challenge. The authors focused on the dynamic state of arsenic compounds, and found that hot spring water contains these arsenic compounds in dissolved state at high concentrations and that the characteristics of pulled runoff change from point source pollution (dilution pollution) to non point source pollution (runoff load increase pollution) in the flow process of the river. This change seems to closely involve water storage in dams, and we gathered that arsenic as a component of hot spring water entering the Toyohira River accumulates in dam sediment by absorption in silt and clay and that the runoff and re-dissolution of silt and clay at times of high flow rate causes the runoff and return of arsenic to the river. It was revealed that sediment in dams is a potential source of arsenic pollution.

Factors affecting dam sedimentation and discussion from ecosystem conservation

Factors affecting dam sedimentation and discussion from ecosystem conservation

Characteristics of dam sediments with heavy metals at the Jinzu River, Toyama, Japan, and the experiment of bacterial bioremediation

Characteristics of dam sediments with heavy metals at the Jinzu River, Toyama, Japan, and the experiment of bacterial bioremediation

Reuse of water treatment plant sludge and dam sediment in brick-making

In this study, an attempt was made to use water treatment plant (WTP) sludge and dam sediment as raw materials for brick-making through the sintering process. The sinter of dam sediment fired at 1,050 degrees C had a less than 15% ratio water absorption, and its compressive strength and bulk density met the Chinese National Standard (CNS) for first level brick. The WTP sludge sinter made under the same operating condition exhibited higher water absorption, larger shrinkage, but poorer compressive strength. When fired at 1,100 degrees C, the shrinkage of the WTP sludge sinter was as high as 45%, although its compressive strength and water absorption of WTP sludge brick still met the standard for the first level brick. To reuse WTP sludge in an economical way, mixtures of various proportions of WTP sludge to dam sediment are used as raw materials. A satisfactory result was achieved when the ratio of the WTP sludge was less than 20% of the mixture. Results of tests indicated that the sinter of dam sediments which are fired at a temperature of 1000 to approximately 1100 degrees C has reached the requirement for tile brick.

Economics of reservoir sedimentation and sustainable management of dams

Accepted practice has been to design and operate reservoirs to fill with sediment, generating benefits from remaining storage over a finite period of time. The consequences of sedimentation and project abandonment are left to the future. This ‘future’ has already arrived for many existing reservoirs and most others will eventually experience a similar fate, thereby imposing substantial costs on society. Such costs could be avoided if sedimentation was minimized and dams were allowed to live forever. The fact that the world’s inventory of suitable reservoir sites is limited provides an additional reason for encouraging the sustainable management of dams. This paper provides a framework for assessing the economic feasibility of sediment management strategies that would allow the life of dams to be prolonged indefinitely. Even if reduced accumulation or removal of sediment is technically possible, its economic viability is likely to depend on physical, hydrological and financial parameters. The model presented incorporates such factors and allows a characterization of conditions under which sustainable management would be desirable. The empirical implementation of the model draws upon the substantial amount of technical information available. We analyze the sustainability of reservoirs, with a focus on the trade-off between such sustainability and the short to medium term benefits which a reservoir is expected to produce. The results show that, for a very wide range of realistic parameter values, sustainable management of reservoirs is economically more desirable than the prevailing practice of forcing a finite reservoir life through excessive sediment accumulation.

The Maude Weir sediments. 2. Effect of weir storage on magnetic properties and associated chemistry

The magnetic properties of river sediments have been used to determine the sources of sediments. However, changes in magnetic properties during transport and sedimentation may occur. This paper examines the effect of reduction on the magnetic properties of sediments from the Maude Weir, NSW. For all sediment samples from the Maude Weir, for both cores and grab samples, there was an inverse relationship between particle size and concentration of magnetic minerals,as measured by magnetic susceptibility. The magnetic grain size, as measured by the ratio SIRM/𝒳, declined through the particle size range. This was attributed to dissolution of the finer grains of the magnetic minerals owing to the chemically reduced state of the sediments. As reducing conditions can alter both the concentration and magnetic grain size of sediments, it is important that the state of chemical reduction be considered when using mineral magnetism as a source tracer for dam sediments. There was a good relationship between total Fe and magnetic susceptibility and total phosphorus. The relationships mentioned above applied to all sediment samples and locations, even though there was substantial variation in the particle size distribution of the samples. Copyright © 2000 John Wiley & Sons, Ltd.

The effects of particle breakage and abrasion on the magnetic properties of two soils

As mineral magnetism is used as a tracer for sourcing river and dam sediments, changes in the magnetic properties that may occur during transport between the source and sink must be considered. Abrasion and breakage of particles will occur during transport. These processes were examined in simulation experiments with a granitic and a sedimentary soil. The effects of these processes on the magnetic properties of a granitic and a sedimentary soil were examined using a simulated breakage/abrasion experiment. Breakage and/or abrasion had substantial effects on the magnetic properties of both soils. All particle sizes were affected, but the magnitude varied through the size range of derived particles. The major effect was on the concentration of magnetic minerals, with differences between the concentrations in particle sizes of the original material and those generated by the experiments being as much as 20 times. The effect on the granite soil was to reduce the concentrations, i.e. derived material was less than original material; whereas for the sedimentary soil the derived particles had higher concentrations. The effect on magnetic grain size, as indicated by the magnetic ratios, was less than the effect on the mass magnetic properties, but still substantial for some ratios for some sizes. © 1998 John Wiley & Sons, Ltd.

Numerical Method for Sedimentation in Sabo Dams (Part 1)

Numerical Method for Sedimentation in Sabo Dams (Part 1)

Numerical Method for Sedimentation in Sabo Dams (Part 2)

Numerical Method for Sedimentation in Sabo Dams (Part 2)

Metal pollution by old lead-zinc mines in Urumea river valley (Basque Country, Spain). Soil, biota and sediment

Soil, aquatic biota (moss: Brachythecium rivulare; aquatic macrophytes: Juncus effusus, Potamogeton crispus; fish: Salmo trutta fario, Anguilla anguilla, Phoxinus phoxinus, Chelon labrosus) and sediment samples from the Urumea river valley were analysed for metals by acid digestion and atomic absorption spectroscopy. The sediments show the presence of metal pollution (Cd: 2.5–24 mg kg-1; Pb: 125–1,150 mg kg-1; Zn: 125–2,500 mg kg-1) because mining and industrial wastes. A selective retention of dense minerals in dam sediments contributes to the load of metal, but interstitial water analysis (Cd: ), but they are used, indistinctly, for farming and pasture.

Mouvements de masse et torrentialité : cas du Tuébi et de la haute-Tinée, Alpes-Maritimes (France)/Mass movements and torrential activity: two typical examples in the French Maritime Alps: Tuébi and Upper Tinée valleys

Abstract The extreme manifestations of torrential activity sometimes observed along some reaches of mountain rivers are commonly due to sediment inputs by feeder torrents but even more by inputs from hillslope mass movements. This relationship is illustrated by two typical examples of torrents on the steep, high-relief setting of the Alpes-Maritimes in southeastern France. The Tuébi has been characterized, in historic times, by a considerable increase in its bedload and by morphodynamic activation of its channel as a result of the progressive gully erosion of a major ancient feeder landslide located a few kilometers upstream. The Upper Tinée exhibits a channel overfilled by alluvium derived from the erosion of the rockslide of the Pra. Torrential reworking of the stream bed fill undermines the efficiency of a sediment dam and an underground tunnel constructed so as to minimize the flood hazards liable to be caused by another mass movement, the megalandslide of La Clapière situated downstream and capable of blocking the valley. A few recent floods have clearly highlighted the inadequacy of the sediment dam, incapable of stopping boulders that are liable to damage houses and infrastuctures.

Further statistical evaluation of the occurrence of keratinolytic fungi in dam sediments

The study was to determine the concomitant effects of selected physico‐chemical and microbiological factors on the qualitative and quantitative composition of keratinolytic fungi in sediments of two dam reservoirs, ‘Przeczyce’ and ‘Plawniowice’. The stepwise forward regression analysis was used. The results were compared with those obtained by the simple linear regression analysis. On the basis of the results obtained, several groups of keratinolytic fungi were recognized. It was confirmed that Trichophyton terrestre together with Arthroderma qurreyi are associated with unpolluted and slightly polluted waters. Chrysosporium keratinophilum, Ch. pannicola, T. ajelloi and Aphanoascus spp. are characteristic for badly polluted waters. Ch. keratinophilum and Ch. pannicola depended on the quantity of micro‐organisms in water and sediments whereas T. ajelloi and Aphanoascus spp. on the input of easily degradable organic matter (BOD5) and suspended solids to the water. A. terreus was independent on the degree of ...

Effects of a little flow on Sabo dam sedimentation in Nukkakushi-Furano River

Effects of a little flow on Sabo dam sedimentation in Nukkakushi-Furano River

Relationship between erosion and energy in North Africa

The increasing pace of water resource exploitation with the aim of developing water resources all over Morocco brings with it a greater and greater need to have a through knowledge (both in theory and in practice) of the widespread erosion of drainage basins, of the resulting flow of fluvial solids, and of the silting up of reservoirs. The better our understanding and assessment of these hazardous phenomens, the more appropriate will be the anti-erosion development and management plans for the dams and associated structures (canals, etc.) in reducing a build up of solid matter in basins and in increasing their useful lifespan. In order to adopt an appropriate plicy for reducing the negative impact (through the completion of anti-erosion devices), we will shed new light on methods used up to now, and on strategies to be adopted in the short, medium and long terms, as far as technology as well as legal aspects and planning are concerned. The following analysis is an important contribution to the understanding and precise measurement of the complex factors connected with the erosion of drainage bassins, the flow of fluvial solids, the sedimentation of reservoirs and associated structures and also the allubation of small-sized lakes. It will cast a new light on existing and future types of anti-erosion treatment for all Morrocan drainage bassins. The need to bring about and to increase the development of modelling of the transport and suspention of slids, as well as that of the sedimentation of reservoirs is leighlighted. A series of sampling procedures to measure the aforementioned transport of solids and totals will be presented with an aim to their being used in a national context in order to complete our theoretical and practical knowledge of the complex factors of alluviation of wadis and reservoirs. We will also discuss the social, economic and environmental impact of the sillting up of reservoirs in the short, medium and long term, as well as the effect of earth filling (in drinking water reservoirs) on eutrophication, the sliding of banks, the risks of flooding caused by the raising of the streatches of water in rivers upstream from important sliding of banks, the risks of flooding caused by the raising of the streatches of water in rivers upstream from important Moroccan dams. Lastly it is worthwhile that we should point out the absolute necessity of starting to undertake multi-criteria and systematic economic impact studies using a maximum number of parameters related to erosion, the transport of solids, the silting up of reservoirs in order to show external losses due to such factors in the corresponding analytical matrix inputs. In North Africa countries (Algeria, Tunisia and Morocco), the high degree of climatic fluctuations and tread patterns, the flux torrentiality, the lower vegetable cover, the excessive soil exploitation, have great impacts on erosion, yield sediment, fluvial transport, on dam sedimentation problems and, consequently, on socio-economic parameters of these countries. The following analysis, based on reservoir silting-up data of 55 dams in North Africa, and on turbidity measurements observed in gauging stations (78 turbidity samplers), reviews of relationships between sediment yields from the watersheds and their surface area, their dominant lithology and their annual mean run-off, they have been used to establish a serie of formulae for prodicting the rate of siltation of dams before their construction and for various dominant lithologies.

Determination of mercury and other elements in La Zacatecana Dam sediment in Mexico

Sediment samples from the La Zacatecana Dam together with samples from two sites, at 7 and 180 km N.W. of the dam, were analyzed by instrumental neutron activation analysis and the concentration of mercury and 28 elements; As, Au, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Ga, Hf, K, La, Na, Nd, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, U and Zn are reported. The ratio between the concentration of an element in the dam sediment and the average concentration at the other two sites (i.e. enrichment factor (EF) of the element) was calculated. Mercury showed an EF of 194. As, Au, Sb, Sm and Zn showed EFs of between 4–11. The EF for the rest of the measured elements was ∼ 1.

Complex channel response to flow regulation: Cudgegong River below Windamere Dam, Australia

Windamere Dam is located on the Cudgegong River near Mudgee, Australia, and was built for irrigation and town water supply. It is operated in a similar manner to the other large irrigation dams in New South Wales. The response of the Cudgegong River to flow regulation since dam closure in February 1984 was determined for 13 km of river downstream of the dam where the channel is a bedrock-confined gravel-bed stream. Mean daily flows for durations less than 70 per cent have been reduced by between 20 and 73 per cent and those for durations greater than 70 per cent have been increased by between 58 and 496 per cent. The dam has reduced downstream flood magnitudes for all recurrence intervals by between 57 and 72 per cent. The dam's sediment trap efficiency is estimated at greater than 95 per cent of the incoming sediment load. Complex river response was induced by flow regulation, and included simultaneous channel contraction, degradation, aggradation, accommodation adjustment, formation of tributary-mouth bars and in-channel benches, and massive vegetation encroachment at different locations. Mean bed-material size decreased at all aggrading sites. Regulated flows are incompetent for the transport of the bed material but large floods generated in unregulated tributaries below the dam exceed the threshold of motion at channel constrictions. These unregulated tributaries now supply the majority of sediment to the channel. This material is reworked by dam releases which preferentially remove the fines and deposit them in downstream pools and on in-channel benches. Vegetation has invaded these recent deposits.

Sediment yield mapping using small dam sedimentation surveys, Southern Tablelands, New South Wales

Summary Sediment yield estimates from sedimentation surveys of small farm dams are a cost effective method of obtaining long-term data suitable for use in catchment management. In this study, the results of a number of such surveys on the Southern Tablelands of New South Wales are used to derive empirical equations for sediment yield in relation to catchment characteristics. The equations are used to estimate the distribution of sediment yield in an adjacent catchment of similar morphology. In areas where numerous such dams have been built this approach can be used to derive sediment yield data for a wide variety of terrain and land use types, which can then be extrapolated to larger areas for which no data exist.