Nach oben pdf Morphological Changes of Reach Two of the Nile River

Morphological Changes of Reach Two of the Nile River

Morphological Changes of Reach Two of the Nile River

The Ministry of Water Recourses and Irrigation (MWRI) is constructing new barrages to replace the existing structures and to ensure the constant supply of water to the downstream. The new barrages incor- porate as hydropower annex to utilize the natural resource of the Nile River for hydropower generation. They also improve the navigation in the Nile River via new locks. On the other hand, for any new barrage there are probable negative impacts such as:

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Simulation of Sediment Transport Due to Dam Removal and Control of Morphological Changes

Simulation of Sediment Transport Due to Dam Removal and Control of Morphological Changes

For the 10-year average bed changes, Figure 3 shows that there is an increasing erosion upstream (Figure 3a), and a continuing aggradation in the immediate downstream of the dam (Figure 3b). It is obvious that the travelling wave of the eroded sediments from the reservoir causes these morphological changes. The rate of upstream bed erosion seems slightly slower than that of deposition downstream; One of reasons is that the downstream cross-sections are narrower than those upstream inside the reservoir. Meanwhile, erosion is also highly related to the initial bed material size. It is expected that following dam removal, the slope of the riverbed would gradually return to the pre dam condition. The results show that the bed changes from year 5 to year 10 are much more than those from year 3 to year 5. This is because the peak discharges in the second five years are significantly greater than those in the first five years. And more river waters in the second five years create more bed changes at a few cross sections around 4 km and 7 km (not plotted in the figure). It is also found that there is an increasing erosion at a reach from 1.4 – 1.8 km, due to accelerated river flows by the narrow cross sections in the reach. The computed trend of the bed changes depends on the hydrological conditions of the selected water years. If more cycles of simulations of the ten water years can be repeated, an equilibrium state of morphology may be found, which remains as a future topic of this study.
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Development of a hydro-morphodynamic model for simulation of bed load and morphological changes of flash-floods (Têt River, France)

Development of a hydro-morphodynamic model for simulation of bed load and morphological changes of flash-floods (Têt River, France)

Abstract — Mediterranean coastal rivers are subject to the climate hazards. Most of the year, they present low water levels with low flows and during intense and short rainy events, their flow increases sharply. These "flash-floods" comprise an intense advancing water wave that induce considerable sediment loads. Most of the solid flows through coastal rivers take place during these brief events. Besides, the materials transported by the river significantly impact the river morphology. These changes may promote floods, destabilize hydraulic structures and disrupt their operations. To analyse the amounts of sediment bed loaded by the Têt River (Gulf of Lions, France) and their effects on the river morphological changes during floods events, we implemented a hydro-sedimentary model (hydrodynamic and sediment transport processes, TELEMAC-2D-GAIA) over the last 12.5 km reach (up to the river mouth). Hydrodynamics calibration was performed on two recent floods events over Manning coefficients. Validation on a third event led to a NSE (coefficient of Nash–Sutcliffe efficiency) of 0.66. Despite several simplifications, the morpho-dynamics model provided reasonable performance regarding the bed load transport. A test of sensitivity on the transport formulae conducted to choose the Meyer-Peter and Müller formula. After investigations on model limitations, we examined the morphological impact of a flash flood on the river. Further researches will focus on simulation of the 100-year flood induced by the 2020 Gloria event.
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Towards management and regulation of gravel mining in urban areas: application of an optimization/morphological model to Maipo river

Towards management and regulation of gravel mining in urban areas: application of an optimization/morphological model to Maipo river

ABSTRACT: Gravel extraction from a natural streambed combined with changes in flow discharge in re- sponse to water resource usage may induce modification of instream sediment transport characteristics. Reduced transport capacity and riverbed overexploitation can bring a system off its natural equilibrium, resulting in decreased sediment replacement downstream from the extraction area but also affecting up- stream morphological conditions. This, in turn, may affect civil works founded in the riverbed, as well as water catchment infrastructure designed upon minimum river stages. In this paper, a methodology is pre- sented to couple a sediment transport and morphological simulation model with a management model based on genetic algorithm optimization, to search for good gravel mining practices, determining ade- quate gravel extraction rates and water use in the system. The model is applied to a hypothetic system in- spired on the Maipo River, located near Santiago, Chile, using data representative of current conditions for sediment extraction rates and water use in a reach that includes an urban area. A first step toward in- tegrated water and sediment management is proposed, evaluating the economic impact of combined se- diment and water use policy in the hypothetic river. The results of the application provide the identifica- tion of sensitive areas together with points where gravel exploitation is possible or even beneficial. The model also yields limiting extraction rates for sustainable operations.
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Trap efficiency of reservoirs on the Nile River

Trap efficiency of reservoirs on the Nile River

A numerical study using one, two and three dimensional models has been carried out by the Institute of Hydraulic and Water Resources Engi- neering and the Oskar-von Miller Laboratory, Technical University of Munich (TUM) for a 236 km long river reach from the city of Atbara (km 327.5) to the El-Koro gauging station (km 563.5). For the 1D numerical model MIKE11 was used as required by the consultant (LI) to estimate the long-term water and bed level changes due to res- ervoir impounding and to optimize the effects of sediment flushing activities during flood times both on the reservoir capacity and on backwater effects.
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Connecting Cairo to the Nile: Renewing life and heritage on the river

Connecting Cairo to the Nile: Renewing life and heritage on the river

gregate here and the small terminal platform becomes crowded and chaotic during ferry arrivals and depar- tures. Ferry arrivals create Maadi’s most prominent pe- destrian nodes as departing passengers gather at infor- mal minibus stops along the Corniche and create traffi c jams. Two main entrances from the Corniche to Maadi neighborhoods also lead to frequent traffi c jams. A gen- eral lack of suffi cient parking spaces, particularly in eve- nings when private waterfront establishments open for business, contributes to additional traffi c congestion. Th e traffi c congestion along the Corniche coupled with obstructed views and unpleasant sounds and smells from the private waterfront facilities contribute to a sub- optimal pedestrian experience along the Corniche in Maadi. Buildings, rooft ops, and exposed garbage areas and ventilation systems not only block views of the Nile, but create unpleasant sidewalk conditions. Unpleasant odors and noise radiate from the restaurants along very narrow sidewalks. At certain points where the sidewalks widen, military or police facilities, or electrical trans- former boxes oft en block the pathway. At these widened areas, the lawn and sidewalks are in poor condition, the formerly grand decorative promenade elements look old and decayed, and debris lines the sidewalks. Addition- ally, although the river is wide at this stretch of the Nile, most days the haze from air pollution obstructs the view across the channel even at the few places where pedestri- ans can reach the river’s edge.
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Numerical Simulation of Sediment Transport and Morphological Change of Upstream and Downstream Reach of Chi-Chi Weir

Numerical Simulation of Sediment Transport and Morphological Change of Upstream and Downstream Reach of Chi-Chi Weir

2. Approaches 2.1 CCHE2D Hydrodynamic and sediment transport model The CCHE2D model is a state-of-the-art numerical modeling system for two-dimensional, unsteady, turbulent river flow, sediment transport, and water quality prediction. The model is also designed for applications to multiple-process simulations in surface waters with complex geometry such as river bed and bank erosion with both uniform and non-uniform sediment and meander river migration. The model can be used for designing and evaluating the effects of the hydraulic structures, such as grade control structures, dikes, etc. The CCHE2D model uses a hybrid numerical method, the Efficient Element Method (EEM), which takes the advantages of both the Finite Element Method (FEM) and the Finite Volume Method (FVM). Depth-integrated two-dimensional equations (the continuity equation, the momentum equations, the k-εturbulent equations, the sediment transport equations, etc.) are solved with multiple capabilities such as turbulent flow, wind-driven flow, tidal flow, and flow with vegetation effects (Jia and Wang, 1999, 2001a, and 2001b).
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Assessing the likelihood of regional climate change over the Nile River basin and northern Africa: A hybrid assessment

Assessing the likelihood of regional climate change over the Nile River basin and northern Africa: A hybrid assessment

2 Characteristics of regional climate shifts 2.1 Greater Nile River basin The greater Nile River basin (Figure 1) is one area of focus for this risk-based assessment of regional climate change. In addition, northern Africa is also summarized. These two regions, which complement a previous analysis of southern Africa, flank the Congo and greater Zambezi River basins (Schlosser et al. 2013; Schlosser and Strzepek 2013). As such, these analyses collectively serve to provide a more geographically comprehensive likelihood assessment of regional climate changes over northern Africa. The two climate variable inputs of interest herein are precipitation and near-surface air temperature (T a ). As described in Schlosser et al. (2013), many impact models are configured to resolve the major sub-basins and demographic regions of the basin, and the climate variables considered in this study are at a 2  2  grid resolution. Overall, the Nile region and northern African experience distinct seasonal hydro-climates. The warmest temperatures are seen in the central portion of the Nile River basin and the strongest seasonality of temperature is located over the northern-most portion of the Nile region (Figure 2). The more persistent cooler temperatures lie within the central and eastern flanks of the Nile focus area (boxed area in Figure 2). Over many parts of the basin and focus region, a weak to modest seasonal swing in temperature is experienced and is in the order of 2–6  C; the strongest seasonal amplitudes in the order of 10  C are found in the central parts of the basin.
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Morphological characteristics of the river Rhine between Iffezheim and Bingen

Morphological characteristics of the river Rhine between Iffezheim and Bingen

ABSTRACT: The objective of the present study is an analysis of the morphological development of the river Rhine between Iffezheim and Bingen (km 335-530), focusing on the period between 1990 and 2008. This analysis forms the basis for an optimization of the existing river training structures and maintenance strategies. The input data used for the investigation are sediment transport measurements, echosounding data and dredging/sediment supply data. Potential errors in these input data are discussed. The analysis shows that in its present state, being altered by extensive engineering works during the last two centuries, the river Rhine is morphologically not in a dynamic equilibrium state. For the echosounding measure- ments a scale-dependent consideration of the data is required. On a large scale (10² km) the morphologi- cal development between 1990 and 2008 was characterized by general bed degradation. Only a few river sections had a stable bed, or were subject to bed aggradation. Furthermore, the analysis reveals that with- in the study reach, the bed load transport rate decreases in the downstream direction, whereas the trans- port rate for suspended load increases. A small-scale consideration (10 1 km) of the bed variations reveals a more frequent change between zones of aggradation and degradation, respectively. These changes ex- press sediment movements that are linked with local effects of changing channel geometry, river training structures, sediment supply or dredging.
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The analysis of factors inducing and inhibiting morphological changes of the Warta river reach downstream of the Jeziorsko reservoir (Poland)

The analysis of factors inducing and inhibiting morphological changes of the Warta river reach downstream of the Jeziorsko reservoir (Poland)

The presented model consists of partial differential equations (PDEs) (2) – (4), the additional formulae (5), (9), (13) and initial and boundary conditions (6), (7). This is the system of nonlinear hyperbolic PDEs. The domain of the problem is 0 ≤ x ≤ L and t ≥ 0. If the formulae (5), (9), (13) are substituted into equations (2) – (4) the system consists of three PDEs with three dependent variables: Q (x, t), h(x, t), z b (x, t). The application of the accurate analytical methods to solve the problem is practically impossible due to the complex nature of the presented mathematical model. The approximate numerical methods have been used for the simulation of many physical processes for long time. In the analyzed case the decomposition of the PDEs’ system and application of a few different numerical methods is forced by the complexity of the problem. The first step is the separation of the water flow and sediment transport equations. Such approach is consistent with different dynamic of these two processes. The changes of the water flow parameters as discharge and depth are much more faster than changes of bed elevations.
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Morphological Characterization of the Lower Reach of the Tenryu River

Morphological Characterization of the Lower Reach of the Tenryu River

The present study is aimed to characterize some major changes in the lower reach from Kashima site (RM 25km) to the river mouth. The particular objective of this paper is to present a holistic view on how the lower reach was affected by a second order impact of dam, which is the intrusion of vegetation into middle bars and floodplains. The analysis was based on the examinations of cross-sectional survey data, flow discharges, vegetation data and aerial photos as well.
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Reconstructing the impact of environmental changes on the river sediment dynamics of the Amazon River and Rio de la Plata drainage basins with radiogenic isotopes

Reconstructing the impact of environmental changes on the river sediment dynamics of the Amazon River and Rio de la Plata drainage basins with radiogenic isotopes

Numerous studies have investigated the chemical and mineralogical composition of the Amazon River and its tributaries’ water and sediment load in order to characterize the different source areas and to understand the influence of distinct processes as e.g. sedimentation, transport and weathering on these signatures (e.g. Medeiros Filho et al., 2016; Guyot et al., 2007; Santos et al., 2015; Vital and Stattegger, 2000). In contrast to the elemental composition, the radiogenic isotopes are not influenced by these processes making them particularly suited for provenance studies. The Sr, Nd and Pb isotope composition of SPM from the Amazon River and its tributaries is poorly known and most of the existing data are from the Solimões and Madeira Rivers, both draining the Andes (Allègre et al., 1996; Bouchez et al., 2011; Viers et al., 2008). Only limited values are available for the main channel of the Amazon River and the Shield draining Negro, Tapajós and Xingu Rivers (Allègre et al., 1996; Bouchez et al., 2011). Several studies have shown that the main sediment supplier to the modern Amazon River (Filizola and Guyot, 2004; Meade et al., 1985) and during the late Quaternary (Govin et al., 2014; Milliman et al., 1975) are the Andes. There is, however, evidence for small variations in the proportions of Andean and cratonic Shield material within the Amazon River SPM. Given the continental extension of the Amazon River basin, even small variations may have large paleoenvironmental implications. Horbe et al. (2014) report a shift in Sr and Nd signatures from a more cratonic Shield component in Quaternary floodplain sediments of the Solimões River to more Andean material in modern Solimões River SPM. McDaniel et al. (1997) studied Nd and Pb isotopes on glacial stage sediments from the Amazon fan and suggested that Pleistocene muds have a more cratonic composition. The identification and interpretation of changing source contributions in the past relies on an accurate knowledge of the modern Sr, Nd and Pb isotopic composition of the Amazon River and its tributaries.
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Advancing REACH - REACH and substitution

Advancing REACH - REACH and substitution

Produktbezogene Rechtsvorschriften verwenden spezifische Ansätze zur Beschränkung gefähr- licher Stoffe in Produkten. Sie unterscheiden sich teilweise von den Ansätzen, die unter REACH zum Einsatz kommen. Erfahrungen aus der Analyse dieser Vorschriften ermöglichten es uns, eine Reihe weiterer Empfehlungen abzuleiten. Auch hier ist das Ziel, Substitution zu stärken – sowohl unter REACH als auch im Zusammenspiel mit anderen, produktbezogenen Gesetzen. Weiter oben (Empfehlung 9 im Kapitel 1.5.5) wurde bereits dargestellt, dass die Bewertung von Gruppen von Stoffen REACH genutzt werden, um ein breites Spektrum problematischer Stoffe in der Stoffbewertung und -regulierung abzudecken. Sowohl die RoHS-Richtlinie als auch die Ökodesign-Richtlinie erläutern, wie ein effektiver und weitreichender Gruppierungsansatz aussehen könnte (z.B. durch gemeinsame Regulierung aller polybromierten Diphenylether und der gesamten Gruppe der bromierten Flammschutzmittel).
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Morphological and anatomical investigation of New Caledonian
graminoid Dendrobium (Orchidaceae) with the description of two new species

Morphological and anatomical investigation of New Caledonian graminoid Dendrobium (Orchidaceae) with the description of two new species

Dendrobium unicarinatum While preparing his treatment of Orchidaceae for the Flore de Nouvelle-Calédonie, Hallé (1977) identifi ed two new taxa in Paris’s herbarium, but the material was too poor to enable a complete description. Over the last several years, additional material has become available and careful comparison with collections from the Pacifi c Islands together with the precise descriptions in the Flora Vitiensis Novae (Kores 1991) show that a part of the material represents a species previously known from Fiji, D. unicarinatum. The other part of the material corresponds to the new taxon D. letocartiorum sp. nov. Dendrobium unicarinatum was included by Kores (1989) in sect. Monanthos, although he mentioned its vegetative resemblances with members of sect. Grastidium, especially D. carnicarinum Kores (1989: 92). While some minor macromorphological differences can be observed (such as apex of the blade and sheath extremity), we doubt they are taxonomically signifi cant. In fact, D. unicarinatum has the same type of sessile infl orescence sheath found in species of sect. Grastidium. On the other hand, several important differences in fl oral characters can be seen. For example, D. unicarinatum has solitary non- resupinate fl owers with an entire lip, while sect. Grastidium is characterised by consistently 2-fl owered infl orescences, resupinate fl owers, and a trilobate and often fi mbriate lip.
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Crime trends through two decades of social changes in Spain

Crime trends through two decades of social changes in Spain

Spain’s social structure has changed dramatically in the past two decades: Strong economic growth at the beginning of the 1980s and the subsequent incorporation of women into the labour market have had important social implications, especially in the family environment. Perhaps the most prominent changes are delayed childbearing and having fewer children, which has considerably reduced the average size of Spanish households. On the other hand, although in the early 1990s the population growth rate in Spain was approaching 0 and thus predicting a population decrease, the arrival of immigrants in the mid 1990s reversed that trend.
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Evaluation of Sudanese Eastern Nile Reservoirs Sedimentation

Evaluation of Sudanese Eastern Nile Reservoirs Sedimentation

When data is scarce or inaccurate, it’s important to look for new approaches that could handle this uncertainty problem properly, hence, Grey System Theory can be an appropriate approach due to its ability of dealing with dynamic uncertain systems , information incompleteness, and inadequacy which are typical features of Blue Nile and Atbara river systems in addition to their highly sediment depo- sition rate -estimated by 140 Million Ton per year- that affected the reservoirs systems, Sennar and Roseires on Blue Nile, Girba on Atbara river, and decreased their storage capacity to be less than 15%, 65% and 47% respectively from their design storage capacity with annual sedimentation rate of more than 40 Mm 3 which impacted severely the system’s reliability to meet the design objectives, where irrigation land has been reduced by 30% besides significant uncertain generated hydropower that have influenced directly the country economic efficiency as most of water resources projects in Sudan are situated at those two rivers region.
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Evaluating the Morphological Compositionality of Polarity

Evaluating the Morphological Compositionality of Polarity

To that end we conduct extensive experiments on a data set with complete morphological parse trees that we compiled from existing resources and which we augmented further.1 This data set is pre- sented in §2. We lay out the features and the setup of our main experiments in §3. Their results are discussed in §4 where we show the efficacy of psy- cholinguistic ratings as features and also demon- strate that a shallower analysis at the level of im- mediate constituents is better than ‘going deep’ to the leaf level. We present an additional set of ex- periments in §5 that shed light on the limits of our results from the main experiment when we attempt to generalize to very different data. We discuss re- lated work in section §6 before concluding in §7.
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The morphological identity of insect dendrites

The morphological identity of insect dendrites

to very basic analysis and small sample sizes. Automatic analysis in a massive and de- tailed manner works best with vectorized, discrete structures. Early vectorized recon- structions resembled neuronal structure as simple node schemes as mentioned before ( Hollingworth and Berry , 1975 ). Here, topological points like branch points and ter- minals of a neuron were modeled as simple graphs of interconnected nodes, thus only preserving the topographic domain. At the same time computer assisted microscope system came up that allowed coordinate based 3D reconstructions of stained neurons ( Macagno et al. , 1979 ). Later, multi-compartmental models were established that also considered the diameters of neurons ( Turner et al. , 1991 ). Here, neuronal branching structure is represented by interconnected cylinders with varying diameters (Fig. 2.6 A and B). These cylinder models represent a realistic but reduced, computationally ac- cessible representation of a neuron, also valuable for functional simulations. So called compartmental models can implement Rall’s cable theory of current flowing in a pas- sive neuronal fiber or it’s active complement defined by Hodgkin and Huxley to model information processing in a biophysically realistic fashion. Each cylinder is thereby seen as a electronic circuit, that connects to other cylinders and is characterized by pas- sive conductance properties and/or active channel dynamics. Thus, faithful cylinder reconstructions can contribute to realistic simulations of neuronal response proper- ties. Many simulation frameworks have implemented support for multi-compartmental models ( Eeckman et al. , 1994 ; Hines and Carnevale , 1997 ; Bower et al. , 1998 ; Gleeson et al. , 2007 ).
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The Economics of Transboundary River Management

The Economics of Transboundary River Management

This analysis of properties is usually done using the axiomatic approach (see e.g. Thomson, 2001, for an overview), a method within cooperative game theory. In line with the above description of studying fairness in the context of social welfare, recent axiomatic studies (cf. Ambec and Sprumont, 2002; Ambec and Ehlers, 2008b; Khmelnitskaya, 2010; Van den Brink et al., 2012; Béal et al., 2012) model river sharing as a cooperative game, where the axioms are imposed on the distribution of welfare to the agents. Recently, Van den Brink et al. (2014) argued that, instead, the axioms should be imposed directly on the allocation of welfare derived from water use, which allows a closer link between the axioms and actual water allocation. In response, Ansink and Weikard (2013) took this argument one step further and imposed axioms directly on the allocation of water. This last approach has the consequence that countries’ benefit functions are ignored. This has the advantage of avoiding some difficulties in implementing cooperative solutions for water allocation, identified by Dinar et al. (1992). A disadvantage is obviously that efficiency is ignored, since, by ignoring benefit functions, we end up in the river claims problem. Whether the axioms are imposed on welfare distribution in a cooperative game, on the allocation of benefits of water use, or on water allocation itself may depend on the characteristics of specific river sharing problems. In some river basins, countries may prefer to allocate physical units of water (cf. Dinar and Nigatu, 2013), while in other basins countries may prefer to allocate the welfare derived from water use (i.e. ‘benefit sharing’), although essentially there is not much difference between the two. Note that in the vast majority of reported negotiations on river water, the subject of negotiation is actual physical units of water, rather than the benefits derived from water use (Beach et al., 2000). In line with this observation Wolf (1999) argues that
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The Battle for the River of Life

The Battle for the River of Life

The EIA for the São Luiz do Tapajós project involved the participation of over 300 people, hired by CNEC WorleyParsons Engenharia SA. The team of researchers presented an analysis containing 25 volumes and 15,000 pages to Ibama. Although the work points to the huge diversity of species in the region, its analysis and methodology contain many flaws and omit information. In other words: the study does not fulfill its main objective: report on the socio-environmental viability of the project. The RIMA presented follows the same line. It is tendentious and ignores fundamental data, like the presence of threatened species and those limited to the stretches of the Tapajós River that will be impacted. In this sense, it serves only as a marketing tool. Read more about some of the main problems found.
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