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JRBM vol 4 Issue 1

The development of a comprehensive flood prevention strategy for Hong Kong
By S.K. Chui, John K.Y. Leung and C.K. Chu
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During the rainy season, flooding can occur in Hong Kong not only over floodplains in the rural areas but also at the older parts of the urban areas. A comprehensive flood prevention strategy has been progressively developed through a series of strategy studies in which considerations were given to the prevailing flooding problems, catchment topography and hydrology, long-term development needs, socio-economic conditions, management issues, and legal constraints. The primary component of the adopted strategy in Hong Kong is a set of flood protection standards for the planning and design of stormwater drainage systems. With these standards being set as targets, there are various structural measures for long-term improvements, non-structural measures as short-term provisions, and planned preventive approaches of maintenance. Other non-structural components include management and administrative measures such as land use planning and control, legislation, warning systems and hazard management plans. Apart from typical river training and on-line capacity improvement, dedicated options including flood pumping schemes to protect building groups located on rural floodplains, and stormwater diversion and retention to minimize excavation works in densely populated urban areas have also been developed to suit the specific local conditions. In this paper, the various phases of development of the flood prevention strategy are presented. The staged implementation of the strategy and the achievements secured are also discussed. Technical details about the various flood control strategy studies and the dedicated drainage improvement options are also given. With the comprehensive flood prevention strategy in place, there is no doubt that the drainage system in Hong Kong is being planned to meet the future demands and that the Government of the Hong Kong Special Administrative Region (HKSAR) is well on its way to providing adequate flood protection level and supporting sustainable development for the benefits of the community.
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Integrated watershed modeling using a Finite Element Method and GIS approach
By T.I. Eldho, A. Jha and Anupam K. Singh
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A watershed is a hydrological unit that can be used as a physical and biological unit and socio-economic-political unit for the planning and management of natural resources. For the appropriate management of a watershed, it is essential to calculate the runoff from a particular watershed for the given rainfall. Hence watershed modeling is very important in water resources impact assessment and watershed management. Due to the complexity of the hydrological processes, watershed modeling requires advanced computational techniques and data management tools, such as the Finite Element Method (FEM) and Geographic Information Systems (GIS). In this research study, the features of FEM have been added to a GIS to take into account the spatial variations of the data of the watershed considered. Effort has been made to integrate these two modeling tools to provide more efficient assessment procedures in watershed modeling. In the watershed modeling procedure, initially overland flow is simulated using the mass and energy balance approach facilitated by GIS. Subsequently the channel flow is simulated by the finite element method, using the kinematic wave model based on the continuity and momentum equations. Finally, both the overland flow model and channel flow model are coupled together to evaluate the runoff. The developed model is applied to an un-gauged watershed for the runoff simulation and the results are found to be satisfactory.
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Evaluation of river velocity and discharge with a new assimilated method
By Yasuo Nihei and Akira Kimizu
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To evaluate accurately river discharge by using the velocities observed at discrete points in a cross section, a new method is presented for data assimilation in which observed velocities are properly incorporated into a river-flow computation. In the present method, a shallow-water flow model is adopted, introducing a new additional term to incorporate smoothly the influence of the observed data into the numerical simulation over the whole cross section. The spatially observed velocities can then be interpolated in a cross section by satisfying dynamic principles for fluid motion. The present method is therefore referred to be here as a dynamic interpolation method. To confirm the fundamental performance of the dynamic interpolation method, the present method has been applied to the spatial interpolation of velocities in a cross section with the simulation data for a river-flow computation done by the authors. The interpolated results indicate that the present method can have high accuracy for the evaluation of river velocity and discharge.
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The effects of bottom settlement, vegetation and macro-roughness on the erosion stability of the relocated River Inde
By Paul Kamrath, Sebastian Rubbert and Jürgen Köngeter
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This paper presents the results of research on a river relocation in the Rhenish lignite mining district of Germany. In the year 2005 the natural river bed will be intersected and relocated as the coal mine moves forward to the east. During flood events exceeding critical shear stresses in the new river bed could cause depth erosion, which would damage or eventually destroy the sealing layer and therefore flood the pit mine as a worst-case scenario. Hence, the distribution of shear stresses, bed load transport and initial depth erosion are calculated for different flood events by means of a 2D depth-averaged hydrodynamic model. The effects of ripple-shaped macro-roughness, vegetation and continued settlement of the river bottom are investigated. The best protection against depth erosion is dense vegetation. The macro-roughness reduces mean velocities on the one hand but increases shear stresses on the other while preventing the development of the vegetation. Locally, structural operations are needed to stabilize the river bed.
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Linking watershed and receiving water models for eutrophication analysis of Tseng-Wen Reservoir, Taiwan
By Jan-Tai Kuo, Ming-Han Hsieh, Wen-Cheng Liu, Wu-Seng Lung and Hung-
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Eutrophication has been one of the most serious water quality problems for Taiwan’s reservoir in recent years. As the water quality of a reservoir is closely related to its watershed development, the fate and transport of pollutants in a watershed is a key consideration to water quality studies in reservoirs. The Tseng-Wen Reservoir, located in southern Taiwan, features the largest storage volume of impoundments on the island. The watershed of the Tseng-Wen Reservoir has significant agricultural activities, such as cultivation of tea, mustard, and betel palm. Fertilizer use for these crops in the watershed is very popular, thereby discharging significant nutrient loads into the reservoir. This study uses a watershed model, BASINS, to simulate the flows and nutrient loads from the watershed; BASINS then drives the CE-QUAL-W2 model for water quality predictions in the reservoir. The watershed model results are compared with data measured at the Dapu Check Dam, in the main stem of the Tseng-Wen Creek. Model results show that significant nutrient and sediment loads are generated from the watershed during storms. The verified model was used to simulate the water quality response to various nutrient reduction scenarios. Both watershed and reservoir models offer a very useful tool for water quality management in the Reservoir.
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Stochastic generation of geomorphological instantaneous unit hydrograph-based flow hydrograph
By Ying Wang and Yeou-Koung Tung
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The geomorphological instantaneous unit hydrograph (GIUH) can be represented as a sum of weighted probability density functions of the rainwater travel times for all plausible flow paths within a watershed. Using the kinematic-wave routing procedure, the rainwater travel time for each overland or channel component is a function of the random channel length, slope and surface roughness coefficient due to their spatial variability. However, limited samples for random slope and surface roughness result in sampling errors which render the determination of statistical moments of component travel times as being uncertain. Hence, the resulting kinematic-wave based GIUH (KW-GIUH) is inevitably subject to uncertainty, which will be further transmitted to the design flow hydrograph. This paper develops a methodological framework to assess the uncertainty features of GIUH-based flow hydrograph which, in turn, could be incorporated into constrained Gaussian simulation algorithm to generate randomly plausible design flow hydrographs.
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Impact of Elevation at Tongguan on flood defence in the lower Weihe River
By Li Changzhi, Wang Zhao-Yin, Wu Baosheng and Wang Wenlong
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The Weihe River is the largest tributary of the Yellow River which discharges into the Yellow River at Tongguan. The lower Weihe River is in the backwater region of the Sanmenxia Reservoir, the first large-scale hydraulic power project in theYellow River. Severe sedimentation has occurred in the lower Weihe River since impoundment of the Sanmenxia Reservoir in 1960. The so-called elevation at Tongguan occurs at the stage while the discharge is 1,000m3/s at the Tongguan hydrologic station, with this being the datum plane of the bed profile of the Weihe River and varies with the reservoir sedimentation and erosion levees. By analyzing the sedimentation and erosion during different periods, this paper studies the impact of the elevation at Tongguan on the flood stages in the lower Weihe River. The sedimentation in the lower Weihe River is closely related to the rise in the elevation at Tongguan, which has been propagating upstream in a series of retrogressive waves at a rate of about 10 km per year. Erosion has taken place in the main channel and sedimentation has occurred over the floodplains during the descending and ascending periods of the elevation at Tongguan. In the lower Weihe River, the water stage has changed with the elevation at Tongguan. The scenario of a 2-m fall in the elevation at Tongguan is studied in terms of the influence on flood stage reduction in the lowerWeihe River. If the elevation at Tongguan is reduced by 2m, then the stages of mid- and small-scale floods will be lowered, but the stage for over bank floods will not change significantly. The bankfull discharge will increase, hence, mid- and small-scale floods can be kept within the channel. However, the risk of a large flood is still high because the stage will be slightly higher if over-bank floods occur. Therefore, a powerful flood defence system is still necessary for mitigation of major flood disasters.
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Relationships between concentration of ions and water and sediment in the Weihe River basin
By Dongsheng Cheng, Zhaoyin Wang, Jiongxin Xu and Cheng Liu
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The concentration of dissolved ions, including K+, Na+, Ca2+, Mg2+, Cl−, SO2− 4 , HCO−3 , CO2− 3 , is an important index for river water quality. By employing the data of measured ions in theWeihe River basin, relationships between the concentration of ions and water discharge and sediment loads are revealed. Generally one of the most important factors affecting the concentration of ions is water dilution, which results in a continuous reduction in the concentration of ions following increasing flow discharge. In a dry season, the concentration of ions decreases with water discharge and sediment concentration; whereas in a wet season, however, the relationships are more complex because the soil erosion can be extremely intensive and sources of ions are rather diverse. Lithology and climate are the two most important influencing factors for these relationships. The Jinghe River and Bahe River are two typical tributaries of the Weihe River. The Jinghe River is from the Loess Plateau and carries extremely high sediment loads, and the Bahe River is from the south rocky mountains and carries a low sediment load. Since there are a multitude of sources of ions and influencing factors in the Jinghe River basin, compared with the Bahe River, the concentration of ions is higher, and relationships between the concentration of ions and water discharge and sediment concentration are much more diverse. The large-scale soil and water conservation strategies performed in the late 1960s have reduced the water and sediment yield from the basin, which have changed the relationships between the concentration of ions and water and sediment. Hyperconcentrated floods happen less and surface erosion becomes the major resource of ions, consequently the relationships between the concentration of ions and sediment and water are more regular. This paper also reveals that if the sediment concentration is higher than a critical value, then the concentration of ions increases greatly, because of intensive soil erosion and especially hyperconcentrated floods, introducing a deeper soil and higher ions into the river system.
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JRBM vol 4 Issue 2

Can conductivity and stable isotope tracers determine water sources during flooding? An example from the Elbe River in 2002
By Johannes A.C. Barth, Willibald Stichler, Michael Bergemann and Heinrich Reincke
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Despite drastic runoff variations, stable isotope data of water in the upstream part of the Elbe River showed remarkable similarity during, and two months after the flood of 2002. This homogeneity indicates that water sources remained the same and most likely represents dominant groundwater input regardless of the flood. While the latter remains the most plausible explanation, it was difficult to prove with water stable isotopes for the upstream part of the river. Overlapping isotope compositions of long-term average precipitation data (as a proxy for the groundwater end member) and of the weighted average from precipitation events in August 2002 did not allow quantification of the groundwater component during flooding. This shows that better spatial and temporal sample resolution is necessary for enhanced understanding of water sources and mass balances during floods. Such mass balances were only possible in the estuary where conductivity and stable isotope tracers both revealed much stronger freshwater fluxes to the estuary during the flooding event of 2002 when compared to those of two months after the flood. Conductivity was also a good indicator for additions of more saline waters from the Saale River when the system was not affected by flooding. However, during the flood in August 2002, large volumes of low-saline waters, most likely from shallow groundwater, masked these usually high conductivity values. This indicates that conductivity better reveals input of dissolved constituents, while the stable isotopes can better indicate sources of water input. Both tracers become most powerful when applied in combination for better understanding of water sources and river basin management.
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Emerging concepts for management of river ecosystems and challenges to applied integration of physical and biological sciences in the Pacific Northwest, USA
By Bruce Rieman, Jason Dunham and James Clayton
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Integration of biological and physical concepts is necessary to understand and conserve the ecological integrity of river systems. Past attempts at integration have often focused at relatively small scales and on mechanistic models that may not capture the complexity of natural systems leaving substantial uncertainty about ecological responses to management actions. Two solutions have been proposed to guide management in the face of that uncertainty: the use of “natural variability” in key environmental patterns, processes, or disturbance as a reference; and the retention of some areas as essentially unmanaged reserves to conserve and represent as much biological diversity as possible. Both concepts are scale dependent because dominant processes or patterns that might be referenced will change with scale. Context and linkages across scales may be as important in structuring biological systems as conditions within habitats used by individual organisms. Both ideas view the physical environment as a template for expression,maintenance, and evolution of ecological diversity. To conserve or restore a diverse physical template it will be important to recognize the ecologically important differences in physical characteristics and processes among streams or watersheds that we might attempt to mimic in management or represent in conservation or restoration reserves.
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An Object-Oriented and OpenGIS supported hydro information system (3O-HIS) for upper Mersey river basin management
By Andrea Leone, Shariar Shams and Daoyi Chen
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An Object-Oriented and OpenGIS supported hydro information system (3O-HIS) is developed taking into consideration the fundamental Open technologies and Open Standards using Java as the core programming language; SQLas the information interchange language; the OpenGIS consortium Specifications as the standard for the GIS application integrated into the system (Open Source projects like OpenMap as Geographical Information System and PostgreSQL with PostGIS extension as relational Database) and the Internet technologies as TCP/IP (communication protocols). The 3O-HIS acts as a platform which can facilitate standard formats for data exchange and code sharing through Object-Orientation and XML. The additional advantages of the 3O-HIS are web-based application with distributed computing and as desktop application; easy integration with different modules based on open source. A validation of the 3O-HIS is conducted against the Upper Mersey river basin with emphasis on portability, extensibility and user friendliness. It is readily available for carrying a wider range of software tools for an integrated water basin management.
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Predictive streamflow uncertainty in relation to calibration-constraint information, model complexity, and model bias
By Michael J. Friedel
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Reliance on basin models by hydrologists to study the effects of changing landscapes on sustainability of water resources is increasing. The success of basin models to provide reliable predictions depends on adequacy of the calibrated model and residual model uncertainty. In this paper, reductions in predictive streamflow uncertainty are demonstrated using streamflow quantities integrated over different sample frequencies as calibration constraints and iterative updating of prior information. Respective model-quality results in terms of coefficient of model-fit efficiencies for cases using published parameter values and no calibration, traditional calibration constrained by daily streamflow measurements, and calibration constrained by various derived streamflow quantities were −0.44 (very poor), 0.66 (fair), and 0.66 (fair) to 0.91 (excellent). Incrementally reducing the number of active excellent-quality-model parameters (from 130 to 6 parameters) reduced the range of uncertainty (from 287.7m3 s−1 to 54.5m3 s−1) when predicting the 500-year peakflow discharge within the Blackberry Creek basin near Chicago, Illinois. The reduction in range of predictive uncertainty, however, coincided with increased model bias for which the 6-parameter model could not predict the 500-yr peakflow discharge. Thus, the hydrologist needs to strike a balance between an acceptable level of model complexity that gives rise to predictive uncertainty and model bias.
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Nutrients/food chain model for Lake Zapotlan (Mexico)
By Mario A. Ortiz-Jiménez, José De Anda and Harvey Shear
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A nutrients/food chain model was developed considering the linkage between water balance and energy balance models for Lake Zapotlan. Lake Zapotlan is located in the southern part of Jalisco State, Mexico, and is classified as a warm, tropical water body, endorheic, very shallow, and highly eutrophic. Kinetic parameters were calibrated using previously reported values in the literature for other lakes. The model simulates the concentration of eight state variables for the lake: algae, herbivore and carnivore zooplankton, nitrates, ammonium, SRP, DOC and POC. A set of eight simultaneous ordinary differential equations (ODE) were generated, assuming an initial set of conditions considering the existing hydrologic and water quality information of the streams flowing into the lake. The ODE system was solved and calibrated by using observed water quality data of the lake. In this way, we have estimated the internal fluxes of nutrients and dissolved oxygen in the lake and their interaction with the food chain.
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Application of the drag force approach to model the flow-interaction of natural vegetation
By C.A.M.E. Wilson, O. Yagci, H.-P. Rauch and T. Stoesser
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Recent approaches in two and three-dimensional numerical models have used a drag force term in the momentum equations to model the stem drag imposed by plants which project through a significant amount of the water depth. This approach reduces the ability to subsume under-represented processes and data uncertainties in the calibration process which are inherent in roughness closures using a bed friction term such as the Mannings n . This paper examines the data uncertainties when applying the drag force approach to flow through natural plants by an a priori determination of the projected area of the plants as a function of height and explores the implications of this relationship on the computed velocity profile. Using eight individual trees of species Salix fragilis, geometric parameters including diameter and volume were measured and the projected area as a function of tree height was determined. Velocity measurements were conducted in the Wienfluss river in Austria and the relationship of drag force as a function of plant height was established for emergent leafless trees. If the velocity profile is fairly constant with plant height it is found that the projected area/plant height relationship may govern the drag force profile. It has been shown that the uniform drag force approach based on a basal or an equivalent diameter results in negligible difference in the computed velocity profile. In both channel cases the uniform approach results in relatively greater velocities in the region close to the bed and lower velocities in the upper region, compared to the non-uniform approach. This resulted in a relative difference of 150% in the computed bed shear stress between the two approaches.
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Book review: Development and flood risk – guidance for the construction industry (J.W. Lancaster, M. Preene and C.T. Marshall) 
By By Richard Dawson
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JRBM vol 4 Issue 3

Effective dam removal and river channel restoration approaches
By C. Katopodis and  L.P. Aadland
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Millions of dams have been built on the planet’s rivers and streams to provide societal needs for freshwater supplies, irrigation, hydroelectric development, industrial activities and flood control. The structural and operational components of most dams include features that reflect technological advancements and changing societal priorities over time. Many dams were constructed and operated with no consideration for river ecology; some dams have included eco-friendly features (e.g. fish passage facilities, instream flow releases); other dams were modified, replaced or removed. Dams have left their mark on the landscape and the biota that depend on rivers for their entire life cycle or for a part of it. Aquatic organisms (e.g. fish) are particularly sensitive to changes in habitat connectivity, hydrograph alterations, morphodynamic modifications, as well as hydrogeologic, thermal or chemical deviations from natural levels. As various societies around the globe, particularly in recent decades, place a higher priority on river ecosystem health and sustainability, effective approaches to deal with existing and new dams are emerging. Restoration of fluvial processes and ecological functions of rivers may take several forms, including dam replacement or removal. Simple removal of dams can result in  sedimentation of downstream habitat, and channel adjustment within the former reservoir may be a long term process before a stable pattern, dimension, and profile becomes established. An alternative approach is to use natural channel design techniques to stabilize accumulated sediment and advance recovery towards a geomorphically stable and ecologically diverse stream. Two approaches and case examples are discussed, one removal with no channel restoration, and one removal with channel restoration. Approaches to dam removal and river restoration involve management, engineering and scientific challenges, demand balanced and sensible resolution, and lead to new research opportunities to fill knowledge gaps of the complex interactions between ecological and physical river processes.
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Validation of chinook fry behavior-based escape cover modelling in the lower Klamath River
By Thomas B. Hardy, Thomas Shaw, R. Craig Addley, Gary E. Smith, Michael Rode and Michael Belchik.
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An emerging trend in the state-of-the-art instream flow assessment applications is the use of three-dimensional channel topography coupled with two-dimensional hydrodynamic models. These components are most often integrated with biological response functions for depth, velocity, and substrate to simulate physical habitat for target species and life stages. These approaches typically involve the simple extension of the one-dimensional conceptual habitat models represented by the Physical Habitat Simulation System (PHABSIM) developed by the U.S. Fish and Wildlife Service (Stalnaker, 1995). However, as demonstrated in this paper, the physical habitat based template represented by high-resolution channel topography and two-dimensional hydrodynamic model outputs can extend these simple conceptual models of habitat to incorporate additional behavior-based decision rules. The approach demonstrated in this paper evaluates the spatial suitability of physical habitat for chinook fry based on the incorporation of behavioral rule sets associated with instream object cover (i.e., velocity refuges) and in-water escape cover type and distance. Simulation results are compared to simplistic based physical habitat simulations using only depth, velocity, and substrate and validated against independent fish observation data. Results demonstrate that the functional relationship between predicted habitat and discharge utilized in many instream flow assessments is significantly different when the additional behavior-based decision rules are applied.
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Flow regime requirements and the biological effectiveness of habitat-based minimum flow assessments for six rivers.
By Ian G. Jowett and Barry J.F. Biggs.
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Sustaining instream values when there is demand for out-of-stream water use is challenging for water resource managers and often there is considerable debate about the methods used to assess flow requirements. Recommendations for flow regime requirements for benthic invertebrates, trout and indigenous fish were made using instream habitat analyses in six New Zealand rivers.We review the results of studies that were carried out to examine the response of aquatic communities to the flow changes. Although the biological data may not be scientifically rigorous in all cases, the weight of evidence from the various sources indicates that in 5 out of the 6 cases, the biological response and the retention of desired instream values, was achieved using the habitat-based methods for setting flows. Indeed, there were increases in trout and benthic invertebrate abundance and changes to the invertebrate community structure in the rivers with successful outcomes. In some cases, flows and flow variability were far from natural, yet excellent trout and invertebrate communities were sustained by the modified flow regimes. High (i.e., flushing) flows were beneficial for cleansing fine sediment deposits and filamentous algae in one river where this regime was recommended and in one case uncontrolled spring floods were necessary to open the river mouth and allow recruitment of diadromous fish species.
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Two analytical approaches for quantifying physical habitat as a limit to aquatic ecosystems
By Robert T. Milhous and John M. Bartholow.
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An early activity in any environmental flow study is the identification of factors limiting both human and environmental benefits derived from the aquatic ecosystem. Limiting factors include (1) physical habitat, (2) water quality, especially water temperature, (3) energy inputs from the watershed, (4) biotic interaction between species, and (5) characteristics of the streamflow regime. Physical habitat is a necessary, but not sufficient, condition for aquatic animals. We present two analytic approaches potentially useful in quantifying limiting factors: quantile regression analysis and dynamic models. Both of these tools are helpful in understanding limits on the aquatic ecosystem caused by characteristics of the physical habitat and other factors. The quantile regression analysis case study presented is for twenty Atlantic salmon streams in Newfoundland Canada, and shows that physical habitat may be limiting along with organic anions and nitrates. The population model example shows that multiple factors may limit fish production, and the importance of a factor can vary between years. The population model calculates mortality as a function of the time series of water temperatures (in turn affecting in vivo egg, fry, and parr lifestages) and dynamic streamflow (affecting the probability of redd superimposition, as well as egg incubation and fry habitat quantity). In any given year, it is the combination of one or more of these factors that tend to control salmon production in the modeled river. Both techniques can help elucidate the relative contribution of the array of potential limiting factors.
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Modeling changes in salmon spawning and rearing habitat associated with river channel restoration
By Mark Gard
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The River2D two-dimensional hydraulic and habitat model was used to simulate fall-run chinook salmon (Oncorhynchus tschawytscha) spawning and fry and juvenile rearing habitat before and after restoration of stream channel sites for a range of streamflows on the Merced River and Clear Creek, California. For the Merced River, hydraulic and structural data were collected for four sites before and after restoration, representing all habitat types within the restoration reach. Habitat simulated for these sites was extrapolated to the entire restoration reach based on habitat mapping. For Clear Creek, hydraulic and structural data were collected for four sites before restoration and pre-restoration habitat was simulated. The topographic plan for the restoration was used to simulate habitat after restoration. While the restoration generally increased spawning habitat, it was less successful for rearing habitat. The results of this modeling show how they can be used in a cost-effective adaptive management framework to evaluate restoration project design prior to construction.
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Patterns of cyprinid migration through a fishway in relation to light, water temperature and fish circling behaviour
By M. Prachalová, O. Slavík and L. Bartoš
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Patterns of cyprinid migration were studied in a fishway located at a lock on the Elbe River, Czech Republic, weekly from spring to fall 2003. 24 hrs observations of fish were made with a Riverwatcher Fishcounter manufactured by Vaki (Iceland). The counter records revealed distinct diel patterns of migration. During spring, fish migrated mostly during the light part of a day, in summer and fall this pattern changed. Water temperature and illumination intensity were found as the major driving forces initiating spawning migration and controlling its development and diel pattern. This hypothesis was verified by significant influence of interaction of weather and atmospheric pressure on the number of migrating fish. Because circling of fish within a pool and between adjacent pools of the fishway was a common behavioural pattern, overestimates of fish migration acitivity occurred, especially in the downstream direction. These results point out that circling behaviour and the effect of weather condition on fish migration should be taken into account in every fishway monitoring effort.
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Standard design of the Dutch pool and orifice fishway
By Wubbo Boiten and Anton Dommerholt.
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In the Netherlands the pool and orifice fishway is mainly intended for fresh water fish with a burst velocity u ≤ 1.00 m/s and which migrates in minor rivers and streams. Here we present the results of a scale model study, which focuses on the rating curve of the fishway and the flow velocity distribution in the orifices. The result of the investigation is a standard hydraulic design of the Dutch pool and orifice fishway for a design discharge 0.050 < Q < 0.150m3/s.
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Book review: Instream flows for riverine resource stewardship (revised edition)
By by Annear, T., I. Chisholm, H. Beecher, A. Locke, P. Aarrestad, C. Coomer, C. Estes, J. Hunt, R. Jacobson, G. Jobsis, J. Kauffman, J. Marshall, K. Mayes, G. Smith and R. Wentworth C.
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By Christos Katopodis
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JRBM vol 4 Issue 4

Tropical Peatland water management modelling of the Air Hitam Laut catchment in Indonesia
By HENK WÖSTEN, ALJOSJA HOOIJER, CHRISTIAN SIDERIUS, DIPA SATRIADI RAIS, ASWANDI IDRIS and JOHN RIELEY
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Human induced land use change and associated fire alter profoundly the hydrology of tropical peatlands and thus affect the functioning of entire river catchments. The hydrological model SIMGRO was used to calculate the effects of drainage on peat water levels, peat surface morphology and river flows within the Air Hitam Laut catchment in Jambi Province, Sumatra, Indonesia. Model outcomes were calibrated and validated using groundwater levels monitored at several sites, discharges measured in the Air Hitam Laut River and flooding patterns derived from remotely sensed Radar images. The validated model was used to predict consequences of three possible scenarios: (i) expansion of oil palm plantations upstream, (ii) expansion of agriculture downstream and (iii) continuing fire damage. Oil palm plantation development results in changes to the drainage pattern of the catchment and reduces its natural extent. Lowered river discharge will have a detrimental affect upon the sustainability of Berbak National Park in the centre of the catchment and reduce prospects for agriculture and fisheries in the coastal zone. Expansion of agriculture downstream causes peat subsidence, resulting in exposure of underlying, acid sulphate soils and intrusion of saline sea water. Continuing fires will increase considerably the area of permanently flooded land and thus constrain peatland restoration options. For peatland restoration to be successful hydrological management must be accompanied by economic measures to improve the livelihoods of local people and by effective law enforcement.
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A generalized relation between initial abstraction and potential maximum retention in SCS-CN-based model
By S.K. MISHRA, R.K. SAHU, T.I. ELDHO and M.K. JAIN.
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Soil Conservation Service curve number (SCS-CN) method estimates direct surface runoff from given amount of rainfall. The initial abstraction coefficient (λ), which largely depends on the climatic conditions, is taken as a constant value of 0.2 in the method and it is perhaps the most ambiguous parameter to be considered for modification. Though the Mishra and Singh (MS) [14] model allows variation in λ and, in turn, initial abstraction Ia , it obviates its dependence on the antecedent moisture M. In fact, larger the antecedent moisture, lesser will be the initial abstraction, and vice versa. This study presents a modification to the initial abstraction (Ia)-potential maximum retention (S) relationship of the existing SCS-CN method and MS model for M. In an application to a large set of data from 84 small watersheds of U.S.A., the proposed modified model for varying λ is found to perform much better than the existing one and other considered variations. The proposed method advantageously obviates sudden jumps in the curve number with antecedent moisture condition, an unreasonable and undesirable feature of the existing SCS-CN model. Finally, a better one-parameter model is also suggested for field applications. This study presents a modification to the initial abstraction (Ia)-potential maximum retention (S) relationship of the existing SCS-CN method and MS model for M. In an application to a large set of data from 84 small watersheds of U.S.A., the proposed modified model for varying is found to perform much better than the existing one and other considered variations. The proposed method advantageously obviates sudden jumps in the curve number with antecedent moisture condition, an unreasonable and undesirable feature of the existing SCS-CN model. Finally, a better one- parameter model is also suggested for field applications.
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Modifying the residence time and dilution capacity of a reservoir by altering internal flow-paths
By SEBASTIÁN MORILLO, JÖRG IMBERGER and JASON ANTENUCCI
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Tracers were released into a small oligotrophic reservoir to determine the tracer dilution ratio (the ratio of inflow to outflow concentration) and two residence timescales (the arrival time and the cleansing time) as a function of lake geometry. The dominant transport mechanisms were inferred by assembling lake-wide spatial and temporal fields of natural tracers such as temperature, pH, salinity, turbidity, and dissolved oxygen from a series of 37-stations. These stations were monitored three times a day during an 8-day field campaign and the field results were compared to numerical simulations of the system. The lake’s hydrodynamic behaviour was successfully simulated with a hydrostatic three-dimensional numerical model (ELCOM) that was used to investigate the deflection from existing flow-paths by means of vertical impermeable curtains. Strategies were tested aimed at modifying the transport timescales and dilution capacity of the lake as may be required for the lake to act as a secure barrier against microbial contamination. Submerged curtains proved to improve the barrier capacity of the reservoir, described by the arrival time, the cleansing time, and the dilution ratio.
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Adaptation strategies to global change for water resources management in the Spree river Catchment, Germany
By HAGEN KOCH, MICHAEL KALTOFEN, MICHAEL SCHRAMM and UWE GRÜNEWALD
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Computer models for long-term simulations of water resources management strategies are used in the analysis of water availability problems in river basins. Such models can also be used for the examination of global change impacts, which are characterised by changed natural water yield and water demand due to climate and socio-economic changes. Already existing water quantity and water quality problems in the catchments of the river Spree and the river Schwarze Elster were analysed in the context of global change. The main water quantity issues are caused by the future development of the mining industry and climate change. The effects of these future developments were analysed using the long-term water resources management model WBalMo. Subsequently, adaptation strategies were defined in co-operation with the relevant stakeholders and their effects analysed with the same model. The results show that continuation of the existing water resources management strategy will not be able to compensate for the impacts of global change. However, a  changed management strategy might compensate the impacts for some users.
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Consequences of supply and demand management options for integrated water resources management in the Jabotabek-Citarum region, Indonesia
By H. HENGSDIJK, W.N.M. VAN DER KROGT, R.J. VERHAEGHE and P.S. BINDRABAN
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In peri-urban areas competition among domestic, municipal, industrial and agriculture water use is strong and calls for identification of alternatives to bridge the widening gap between required and available water resources. In this study, the RIver BAsin SIMulation (RIBASIM) model is applied to explore the potentials of five demand and two supply water management options to improve water allocation in a peri-urban region in order to meet both rural and urban water needs. The Citarum river basin and the adjoining urbanized Jabotabek region in Indonesia are used as a case study. The analysis indicates that the considered demand management options are able to satisfy future urban water demand of the Jabotabek region taken into account agricultural water requirements. All analyzed options share the requirement for an accurate monitoring of the regional water balance and improved information management, while some require additional modification of land use (management). The paper discusses briefly the costs and other implications associated with implementation of the various management options. The presented analysis contributes to the transparency of the debate on local water scarcity problems and provides decision-makers with quantitative information on water allocation problems in densely populated regions with competing sectors.
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Influence of different activities on water quality in a small basin
By JUSTYNA CZEMIEL BERNDTSSON and LARS BENGTSSON
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The relative influence a city has on river water quality depends on the land use within the river basin and the character of the basin. In this paper the small Höje River basin, typical for southern Sweden, is studied; the pollution loading from a number of sources is estimated and the effect of actions taken both in the city and outside on river water quality is evaluated. The results show that agriculture is a major source of nitrogen to the Höje River; however, phosphorus concentrations are largely influenced by urban discharges (storm runoff and treated wastewater) and urban storm runoff carries major loading of heavy metals. Treatment of agricultural runoff or replacement of agriculture with less intensive land use (e.g. forestry, less intensive agriculture) would have the largest relative effect on river nitrogen status. Treatment of urban storm runoff would contribute to minimising heavy metals loadings to the river.
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Numerical modelling of the catastrophic flooding of Santa Fe City, Argentina
By C.A. VIONNET, P.A. TASSI, L.B. RODRIGUEZ and C.G. FERREIRA
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The large plain in the lower basin of the Salado River in west-central Santa Fe State, Argentina, sustains a prolific agricultural activity vital for the local economy. In April–May of 2003, the region suffered the most devastating flood on record for the Salado River, triggered by heavy rains in its lower basin. The west side of the State Capital, Santa Fe City, located at the mouth of the Salado River, was suddenly flooded when a protective levee failed. People living in the floodplains near the city, accustomed to coping with floods characterized by slowly rising water, faced a sudden increase up to 4m of water in a matter of hours. During the flooding of one third of the city, nearly 120,000 people were suddenly displaced from their homes, 23 people died as a direct result of the flood, and other 43 are believed to have died from post-traumatic distress. This work presents a numerical reconstruction of the event, emphasizing the chain of miss-management decisions made over the years that have a share in the worst environmental disaster of Argentina’s recent history.
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