Showing papers on "River engineering published in 2014"

Separating the Impacts of Climate Variation and Human Activities on Runoff in the Songhua River Basin, Northeast China

Abstract: Climate variation and human activities are commonly recognized as two major factors affecting basin hydrology. However, quantifying their individual effect on runoff is challenging. In this study, long-term (1960–2009) river discharge and weather data in the Songhua River Basin (SRB, 556,800 km 2 ), Northeast China, were gathered to separate the impacts of climate variation and human activities on runoff in five sub basins of the SRB. Mann-Kendall test, moving t-test and precipitation-runoff double cumulative curve were utilized to identify trends and change points of the hydrometeorlogical variables. Based on the change point, the 50-year study period was divided into two time series: 1960–1974 where minimal human activities took place and 1975–2009 where extensive land use change occurred and river engineering projects were undertaken. Subsequently, individual contributions of climate and human factors were assessed through a hydrologic sensitivity analysis. Our study found a significant decline in runoff of the SRB over the past 50 years. Contribution of climate variation and human activities to the change varied temporally and spatially. For the 1975–2009 period, human activities made a greater contribution (62%–82%) to the total runoff decline of the SRB. However, climate variation played a bigger role in runoff reduction in two sub river basins (63%–65%) between 1975 and 1989,

Flood routing in branched river by genetic programming

Abstract: Flood routing in branched rivers is an important issue in river engineering. Hydraulic approaches to address the issue involve complex equations that are applied in flood routing with high accuracy but using a lot of data, especially river specifications. In contrast, hydrologic flood routing approaches are simple and employ limited parameters coupled with linear and nonlinear equations based on the continuity equation to route the flood. In the present study, to achieve a routed flood hydrograph considering both accuracy and simplification in the routing process, two hydrologic methods, based on (1) an extended version of the Muskingum method and (2) genetic programming (GP), were applied in a branched river in Iran for 10- and 100-year flood return periods and the results compared with those of the St. Venant equations as a numerical hydraulic method. The results show that GP decreased (improved) the sum of the squared deviation (SSQ) between hydraulic and hydrologic routed outflows by 90·71 and 49·24% ...

Effects of dam operation on downstream river morphology: the case of the middle Zambezi River

Abstract: The sand-bed middle Zambezi River flows between two large dams: the Kariba in Zambia and Zimbabwe upstream and the Cahora Bassa in Mozambique downstream. Since the construction of Kariba for hydropower production in 1959, the river discharge has been regulated according to two different strategies. This makes the middle Zambezi a unique case for studying the effects of different dam operations on the long-term morphological trends of the river. To analyse these effects, this work focused on the interaction between the river morphological changes and the groundwater flow. The comprehensive approach, combining numerical modelling, analysis of field and historical data, as well as theoretical considerations, led to the conclusion that the morphological response of the middle Zambezi to damming has been mainly affected by the sudden closure of the dam flood-gates, originating seepage forces causing bank instability and river widening as a result. The local climatic oscillation, comprising dry and wet periods ...

Adapting to Change in the Lowermost Mississippi River: Implications for Navigation, Flood Control and Restoration of the Delta Ecosystem

Abstract: The Lowermost Mississippi River (LMMR), from the Gulf of Mexico to 520 km above Head of Passes, remains critical for flood conveyance and transport of agricultural and industrial bulk products from the central United States. The US Army Corps of Engineers (USACE) has managed it with little change for 80 years using the levees and spillways constructed under the Mississippi River and Tributaries project (MR&T). At the same time, public demand for reconnection of the Mississippi to the deteriorating delta ecosystem has grown. Significant sediment diversion projects have been authorized downstream of New Orleans to restart deltaic wetland building to conserve fish and wildlife resources and reduce hurricane flood risk to delta communities. Recent research and observations from the back-to-back record 2011 high-, and 2012 low-discharge events indicate that LMMR hydraulics have changed significantly, and that sea level rise, subsidence and a reduction in sand transport through the Plaquemines-Balize birdsfoot delta (PBD) now favor formation of new, unregulated outlets upstream. During the peak of the 2011 flood, only 27 % of the 65,000 m3-s−1 discharge entering the LMMR reached the Gulf via Head of Passes, compared to 36 % passing through the two outlets of the shorter Atchafalaya distributary. About 20 % of the water lost from the LMMR occurred through unregulated flow overbank and through small, but growing, distributaries between New Orleans and Head of Passes. Adding delta restoration to existing USACE missions will require adjusting the MR&T but has potential to lower flood flow lines and reduce navigation dredging costs sufficiently to allow LMMR ports to accommodate larger, Post-Panamax ships.

Monitoring of River Center Line and Width—A Study on River Brahmaputra

Abstract: Monitoring of river width and centerline is one of the most important activities in river engineering. Changes in the width and center line can be attributed to several reasons and monitoring these changes can be conveniently achieved with the aid of remote sensing images. In this study, digital image processing techniques have been implemented using the image processing tool-box available in MATLAB for studying temporal variations of width and centerline of the river Brahmaputra in its 300 Km reach in the state of Assam, India. The current study uses relatively high resolution imageries acquired from the LANDSAT series of satellites. Apart from the LANDSAT imageries, the low resolution imageries acquired by MODIS program is also used in order to see the variation in the obtained results. The evaluation of the results shows that the digital image processing technique is very handy and can be applied to obtain the centerline and width of a river. The evaluation also shows that the low resolution image can also be used for obtaining centerline of a river. However, it may give erroneous result when width of the river is narrow or very large.

Study for restoration using field survey and geoinformatics of the kolong river, assam, india

Abstract: River engineering and the subsequent loss and fragmentation of Riparian habitats during recent centuries have had serious impacts on aquatic ecosystem. The Kolong River of Nagaon, Assam, India has also faced serious penalty of one of such radical engineering approach where the mouth of the river in Jakhalabandha was permanently closed during the year 1964 by constructing an earthen embankment across it, viz. the Hatimura dyke, with the chief objective of protecting Nagaon town against flood. The act of blocking has shattered the natural flow regime of the entire river leaving it in a moribund state. Here we briefly summarize the existing scenario of the study area with an emphasis on a possible river restoration technique. Seven well distributed sampling stations were selected for the study purpose. Water quality and hydrological parameters were determined using standard procedures. Base map, drainage map and landuse/land-cover map of the study area were prepared (Database: Survey of India Topological sheets, LANDSAT satellite imagery and IRS LISS-III satellite imagery) for acquiring a broad apparition about the geo-environmental setting of the study area. Results of the present study reveal the fact that a restoration paradigm is essential for management of the river’s health and ecosystem. A framework of the restoration program is discussed.

The Effect of Hydromorphological Changes on Habitat Composition of the Szigetköz Floodplain

Abstract: Impacts of river engineering, particularly effects of channelisation were studied by analysis of historical maps from the early 19th century in the Szigetkoz floodplain of the Danube River. Different hydrogeomorphological situations were investigated at a study site (Bodaki-branch system), where several deficiencies of altered river ecosystems (areal decline of aquatic habitats, change of bed load transport, decrease of lateral river-floodplain connectivity, etc.) can be recognised. Prior to extensive regulations, the Szigetkoz floodplain was a highly dynamic braided and anabranching channel system. Alteration of the hydrogeomorphological processes by engineering lead to aggradation of river-floodplain ecosystem, formation of several abandoned channels and significant decline of the ecological rejuvenation of the aquatic habitats. Our results indicate long-term changes of landscape dynamics and fragmentation of the river ecosystem from the pre-regulation period up to the present situation.

A review of the Lower Mississippi River Potamology Program

Abstract: The Mississippi River and Tributaries (MR&T) Project is a comprehensive water resources project for flood damage reduction and navigation improvement on the Mississippi River. MR&T elements include levees, floodways, diversion structures, tributary basin improvements, and channel improvements such as meander cutoffs, bank stabilization, dikes and dredging. Understanding how these elements, combined with natural factors, such as floods and droughts, impact the historical, current, and future river morphology is a complex challenge for those tasked with managing the Mississippi River for floods, navigation, environmental restoration, and coastal wetland loss. Mississippi River potamology (the science of rivers) studies advance understanding of how natural and man-made factors combine to impact river morphology regarding present and future flood damage reduction, navigation, environmental restoration, and coastal wetland projects. The US Army Corps of Engineers (USACE) has conducted numerous potamology studies dating from the 1800s to modern times. Major studies were often the result of floods and follow-on beneficial projects. The epic 1927 flood fostered the first official USACE Potamology Investigations that resulted in more than 70 reports. The 1973 flood drove additional USACE potamology studies (T-1 and P-1 reports). However, funding, staffing, and interest in potamology studies waned, becoming almost nonexistent in recent times. Lessons learned and projects implemented from USACE’s 1940s–1980s potamology studies helped pass the recordsetting 2011 flows. The 2011 Mississippi River flood renewed interest in potamology, resulting in the creation of the USACE Mississippi Valley Division’s (MVD) new Mississippi River Geomorphology and Potamology (MRG&P) Program. The first report of the MRG&P was a review of the Lower Mississippi River Potamology Program, including a comprehensive bibliography of potamology reports (Biedenharn et al., 2014). This paper provides a short review of USACE Mississippi River potamology studies.

Determining the Best Method for Estimating the Bed Load through HEC-RAS Model (A Case Study for Taleghan Dam)

Abstract: One of the objectives of river engineering science in sediments studies is to estimate the amount of sediments and to access appropriate methods of estimating sediment transport capacity of the rivers. In order to design river engineering operations, different mathematical models such as HEC-RAS model can be used. In this case, the first step is to stimulate hydraulic conditions of the flow which can be fulfilled by applying the geometric features of the river and flow hydraulic through the abovementioned model. The present research has estimated the amount of input sediment to the reservoir of Taleghan Dam through mathematical model of HEC-RAS and has determined the best method for estimating the bed load among the seven methods of aforementioned model. Using the required data of the model such as geometric shape of the river, data relating to sedimentary materials of the river, data relating to hydrology or river flow, as well as hydraulic conditions of upstream and downstream system and implementing it, the annual amount of input sediment to the dam reservoir was determined through the sediment statistics of Cling station (upstream) and Lushun station (downstream). Then the floor load obtained from the observed data was compared to the results of seven models. The results showed that the best performance belonged to Wilcok method so that according to hydrometric stations data, in the period between 1980 and 1994 the amount of floor load was about 0.734 million tons per year and according to Wilcock method it was estimated to be 0.635 million tons.

Sediment Transport, River Morphology, and River Engineering

Abstract: Unit stream power is the most important and dominant parameter for the determination of transport rate of sand, gravel, and hyper-concentrated sediment with wash load. The unit stream power theory can also be applied to the study of surface erosion. The unit stream power theory can be derived from the basic theories in turbulence and fluid mechanics. Minimum energy dissipation rate theory, or its simplified minimum unit stream power and minimum stream power theories, can be derived from the basic thermodynamic law based on the analogy between a thermo system and a river system. It can also be derived directly from mathematical argument for a dissipative system under dynamic equilibrium condition. The minimum energy dissipation rate theory and its simplified theories of minimum unit stream power and minimum stream power can provide engineers the needed theoretical basis for river morphology and hydraulic engineering studies. The Generalized Sediment Transport model for Alluvial River Simulation computer model series have been developed based on the above theories. The computer model series have been successfully applied in many countries for solving hydraulic engineering and reservoir sedimentation problems. Examples will be used to illustrate the applications of the computer models to solving a wide range of river morphology, river engineering, and reservoir sedimentation problems.

Swiss competences in river engineering and restoration : special session on Swiss competences in river engineering and restoration of the Seventh International Conference on Fluvial Hydraulics (River Flow 2014), EPFL Lausanne, Switzerland, 5 September 2014

Abstract: Preface Organization Sponsors Invited papers Swiss strategy for integrated risk management: Approaches to flood protection and river restoration J. Hess, O. Overney & E. Gertsch Revitalization of rivers in Switzerland-a historical review Ch. Goldi Swiss contribution to bed load transport theories M.N.R. Jaeggi & D.L. Vischer Freeboard analysis in river engineering and flood mapping-new recommendations L. Hunzinger Alpine Rhine Project (Section River Ill-Lake Constance) M. Mahr, D. Schenk, M. Schatzmann & A. Meng Flood protection along the Alpine Rhone river: Overall strategy and 3rd correction project T. Arborino & J.-P. Jordan Flood control and revitalisation along the Aare river between Thun and Berne-experiences with recreational use and other conflicts of interest F. Witschi & B. Kaufeler Flood characteristics and flood protection concepts in the Reuss catchment basin P. Billeter, M. Mende & J. Jenzer Innovative measures for management of bed load sediment transport: Case studies from alpine rivers in western Switzerland G. de Montmollin & A. Neumann Integrated flood forecasting and management system in a complex catchment area in the Alps-implementation of the MINERVE project in the Canton of Valais J. Garcia Hernandez, A. Claude, J. Paredes Arquiola, B. Roquier & J.-L. Boillat Flood protection and river restoration in the urban catchment basin of Cassarate river: An opportunity to restore public areas along an urban watercourse running through the city of Lugano L. Filippini, S.A. Ambroise & S. Peduzzi Intervention and management of floods in mountain rivers and torrents in the Bernese Oberland M. Wyss & N. Hahlen Conference papers Driftwood retention in pre-alpine rivers L. Schmocker, R. Hunziker, U. Muller & V. Weitbrecht Design of a bed load and driftwood filtering dam, analysis of the phenomena and hydraulic design M. Bianco-Riccioz, P. Bianco & G. De Cesare Design of a diversion structure for the management of residual risks using physical model tests A. Magnollay, G. De Cesare, R. Sprenger, D. Siffert & P. Natale From vision to realisation-opportunities and challenges in restoring the river Bunz K. Steffen Physical modeling of the third stage of Aire River revitalisation project Z. Vecsernyes, N. Andreini, D. Consuegra & J.-L. Boillat Restoration of the Broye delta into the Lake of Morat (Salavaux, Switzerland) E. Bollaert, J. Duval, L. Maumary, S. Andre & P. Hohl Hydropeaking and fish migration-consequences and possible mitigation measures at the Schiffenen Dam D. Brunner & B. Rey Flow restoration in Alpine streams affected by hydropower operations-a case study for a compensation basin M. Bieri, M. Muller, S. Schweizer & A.J. Schleiss Morphodynamic changes in a natural river confluence due to a hydropower modified flow regime M. Leite Ribeiro, S. Wampfler & A.J. Schleiss Author index

Danube River Sediment Transport and Morphodynamics

Abstract: Hydromorphological alterations of large rivers are evident and have to be related to multiple anthropogenic pressures. The presented results of an integrated study concerning the actual status of the hydromorphology of the Danube River Basin show that in particular, the sediment regime features a heavily disturbed system at various scales. Combined impacts of flood protection, navigation and hydropower measures applied over a long period of time have been identified based on the river-scaling concept (RSC) for being responsible for these specific alterations (lack of bed load and suspended load in the remaining free-flowing sections). Moreover, long sections of the Danube River have been narrowed, channelized, disconnected from floodplains and morphologically degraded over the last 200 years. This has caused increased bottom shear stresses, increased sediment transport capacities and in addition a lack of lateral self-forming processes and corresponding reduced morphodynamics in the non-impounded sections. As a consequence of both longitudinal and lateral disturbances of the sediment supply and additional impacts of the channelization, the remaining free-flowing sections are subject to various forms of river bed degradation. Such degradation or river bed incision leads to a loss of instream structures in general, with a disappearance of gravel bars at the Upper Danube, and changes of sandbars at the Lower Danube. Hence, for river systems and large river basins, it has to be stated that the preservation and restoration of morphodynamics is one of the most relevant issues for river engineering and ecology. This has to be considered especially for the implementation of legal directives and/or future river basin management plans.

Determination of Friction Factor over a Pool Reach by Double-average Method

Abstract: Bed-form characteristics have been investigated because of the close relation to hydraulic friction. Pool is one of the most important bed forms in coarse-bed rivers. The form friction factor should be considered in determining many river engineering projects including stable channel design, the scour depth along bank protection and at bridges piers. This study was conducted in the coarse-bed, Saymareh river, in western Iran. Two reaches, with Froude number less than 1.0, were selected to investigate the contribution of the double-average method in determining friction factor, one with pool bed form, range of Reynolds numberfrom 1.325×10

Determining the stage-discharge curve and changing it into a regression equation using hydraulic software

Abstract: Constant measurement of the rivers flow in normal conditions is difficult and costly and in flood risk condition it is perhaps impossible due to the measurement problems and probable risks. Therefore, in hydrometric stations through continuous reading of the scale and finding the relationship between stage-discharge, the flow rate is obtained for the times when the measurement is not done. Stage-discharge relationship is a kind of flow resistant equation which is used to determine the flow rate when the hydraulic radius or depth, channel shape, slope, bed material characteristics, and temperature are known. The present research was conducted to determine stage –discharge relationship in the Dez River at different stages. First of all, the needed data were collected including cross sections, hydrological data, hydrometric stations data, etc at the Dez River. After collecting the data, the associated hydraulic models were implemented. The models used in this research are HEC-RAS and MIKE11 software which are important software in river engineering sciences.

Evaluation of Impacts from River Engineering Measures at Nanjing Reach of Yangtze River : An Application of Hydrodynamic Modelling and Sediment Transportation Simulations

Abstract: The demand of electric power has rapidly increased in China along with the financial development. High pollution rates have pushed the development towards more renewable energy generating alternati ...