River Modification Research Articles

Wetlands Drainage, River Modification, and Sectoral Conflict in the Lower Illinois Valley, 1890–1930. John Thompson. 2002. Southern Illinois University Press, Carbondale, IL. 284 pp. $60 cloth.

Wetlands Drainage, River Modification, and Sectoral Conflict in the Lower Illinois Valley, 1890–1930. John Thompson. 2002. Southern Illinois University Press, Carbondale, IL. 284 pp. $60 cloth.

Distribution of the Antillean manatee ( Trichechus manatus manatus) as a function of habitat characteristics, in Bahı́a de Chetumal, Mexico

The Antillean manatee Trichechus manatus manatus is considered endangered because of its reduced numbers, poor knowledge about its population status, and human modification of rivers, estuaries and coastal areas which it inhabits. Previous studies identified some elements of the habitat of manatees in the Caribbean, but few have explored quantitatively their relationship with their use by manatees, specially at a local scale. We explored the correlations between several habitat characteristics and the use of small spatial units by manatees in Bahı́a de Chetumal. Distance to freshwater sources, vegetation cover, depth, slope, salinity and shelter were sampled concurrently during 17 manatee aerial surveys, between November of 1998 and April of 2000. All variables, except shelter, were correlated with the occurrence of manatees. The distance to freshwater and depth contributed the most to multivariate Poisson and Logistic regression models and should be considered first in developing habitat models and conservation strategies for this species.

A simple flow-concentration modelling method for integrating water quality and water quantity in rivers

As part of the determination of the ecological Reserve for rivers in South Africa (National Water Act, 1998), flow requirements are assessed for maintenance low flow, drought low flow and flood conditions. Since water quantity and water quality are often closely linked, it is necessary to ensure that in setting the recommended flow regime, the appropriate water quality will be attained. This paper presents a simple method (based on solute rating curves) for predicting the instream concentrations of chemical constituents that will arise from different flow regimes. The method uses monthly mean flow (discharge) at a given site plotted against monthly median concentration of each chemical constituent. This is carried out for both the reference condition (the natural, or least-impacted state) and for the present state. The flow-concentration relationships obtained are used to predict the expected monthly concentrations under the recommended flow regime. The computed concentrations can be compared with the reference condition and present state values to assess the degree of river modification. This paper outlines the modelling protocol to be followed, considers the limitations and assumptions inherent in the approach, and the application of the resultant information. It is concluded that the modelling method is a useful screening tool for identifying sites where, without reduction of pollution, the water quality component of the Reserve is unlikely to be attained under the recommended flow regime. Water SA Vol.29(3) 2003: 305-312

Relationship among Fish Assemblages and Main‐Channel‐Border Physical Habitats in the Unimpounded Upper Mississippi River

Large rivers worldwide have been altered by the construction and maintenance of navigation channels, which include extensive bank revetments, wing dikes, and levees. Using 7 years of Long-Term Resource Monitoring Program (LTRMP) data collected from the unimpounded upper Mississippi River, we investigated assemblages in two main-channel-border physical habitats—those with wing dikes and those without wing dikes. Fishes were captured using daytime electrofishing, mini-fyke netting, large hoop netting, and small hoop netting. Our objectives were to (1) assess associations among fish species richness, physical measurements, and main-channel-border physical habitats using stepwise multiple regression and indicator variables; (2) identify abundant adult and young-of-year (age-0) families in both physical habitats to further investigate assemblage composition; and (3) calculate standardized species richness estimates within each physical habitat for adult and age-0 fishes to provide additional information on community structure. We found species richness was greater at wing dikes for both adult and age-0 fishes when compared with main channel borders. Stepwise multiple regression revealed significant relationships between adult species richness and passive gear deployment (e.g., hoop nets and mini-fyke nets), physical habitat type, and river elevation, as well as interactions between physical habitat and passive gears, and physical habitat and transparency (i.e., Secchi depth). This model explained 56% of the variance in adult species richness. Approximately 15% of the variation in age-0 species richness was explained by the sample period, sample date, transparency, physical habitat, and depth of gear deployment. Long-term impacts of river modifications on fishes have not been well documented in many large river systems and warrant further study. The findings from this study provide baseline ecological information on fish assemblages using main channel borders in the unimpounded upper Mississippi River, information that will aid managers making channel maintenance decisions in large river systems.

Abundance of Ohio Shrimp (Macrobrachium ohione) and Glass Shrimp (Palaemonetes kadiakensis) in the Unimpounded Upper Mississippi River

Large rivers of the United States have been altered by construction and maintenance of navigation channels, which has resulted in habitat loss and degradation. Using 7 y of Long Term Resource Monitoring Program data collected from the unimpounded upper Mississippi River, we investigated Ohio and Glass Shrimp abundance collected from four physical habitats of the unimpounded upper Mississippi River: main channel border, main channel border with wing dike, open side channel and closed side channel. Our objective was to assess associations between Ohio and Glass Shrimp abundance, environmental measurements and the four habitats to better understand the ecology of these species in a channelized river system. Ohio Shrimp were most abundant in the open side channels, while Glass Shrimp were most abundant in the main channel border wing dike habitat. Thirty-two percent of the variance in Glass Shrimp abundance was explained by year 1995, year 1998, water temperature, depth of gear deployment, Secchi disk transparency and river elevation. Approximately 8% of variation in Ohio Shrimp abundance was explained by Secchi disk transparency. Catch-per-unit-effort (CPUE) was greatest in 1998 for Glass Shrimp but lowest in 1997. Conversely, CPUE was greatest in 1996 for Ohio Shrimp and lowest in 2000. Both species exhibited inter-annual variability in CPUE. Long-term impacts of river modifications on aquatic invertebrates have not been well documented in many large river systems and warrants further study. The findings from this study provide ecological information on Glass and Ohio Shrimp in a channelized river system.

Wetlands Drainage, River Modification, and Sectoral Conflict in the Lower Illinois Valley, 1890–1930

Wetlands Drainage, River Modification, and Sectoral Conflict in the Lower Illinois Valley, 1890–1930

Wetlands Drainage, River Modification, and Sectoral Conflict in the Lower Illinois Valley 1890‐1930

In the United States, many households buy flood insurance to hedge losses due to rivers overtopping their banks and inundating property mortgage institutions require homebuyers to purchase insurance when property lies within the “100‐year floodplain,” where floods have a 1% chance of occurrence each year. Yet haven't we all read about communities experiencing several extreme floods within a few years? Haven't we read about disputes between property developers and community planners over flood risks and flood insurance rates?

Classifying urban rivers

Classification systems have been developed over the last century as a tool to aid managers in the preservation, conservation, enhancement and management of rivers. The classification systems developed to date have been designed to differentiate between relatively unimpacted, mainly rural rivers. Urban rivers typically show poor water quality and biological diversity, and so most current classification systems tend to group urban rivers into a single "poor" category. In this paper we describe a hierarchical framework for recording information about urban rivers that allows a more sensitive description of these rivers enabling subdivision into several classes according to the purpose of the classification. The different levels in the hierarchy, the types of attributes that are to be recorded at each level, and the relational database structure for storing the data are described. The 100-500 m river stretch level in the hierarchy relates to the engineered modification of urban rivers and is the key to their classification. An example classification at this scale illustrates a link between engineering modification, bank and bed materials and the number and diversity of physical habitats present. This classification underlines the importance of adopting a hierarchy of nested spatial scales for data collection, classification and interpretation since it illustrates a clear link between characteristics at the stretch scale and at the finer habitat scale. The classification also illustrates the varied nature of urban rivers and the fact that even quite heavily engineered stretches can contain a diversity of habitat types.

Ecology and biology of paddlefish in North America: historical perspectives, management approaches, and research priorities

Paddlefish (Polyodon spathula, Polyodontidae)are large, mostly-riverine fish that once wereabundant in medium- to large-sized river systemsthroughout much of the central United States. Concernfor paddlefish populations has grown from a regionalfisheries issue to one of national importance for theUnited States. In 1989, the U.S. Fish and WildlifeService (USFWS) was petitioned to list paddlefish asa federally threatened species under the EndangeredSpecies Act. The petition was not granted, primarilybecause of a lack of empirical data on paddlefishpopulation size, age structure, growth, or harvestrates across the present 22-state range. Nonetheless,concern for paddlefish populations prompted the USFWSto recommend that paddlefish be protected through theConvention on International Trade in EndangeredSpecies of Wild Fauna and Flora (CITES). The additionof paddlefish to Appendix II of CITES, which wasapproved in March 1992, provides a mechanism tocurtail illegal trade in paddlefish and their partsand supports a variety of conservation plans. Paddlefish populations have been negatively affectedby overharvest, river modifications, and pollution,but the paddlefish still occupies much of its historicrange and most extant populations seem to be stable. Although many facets of paddlefish biology andecology are well understood, the lack of informationon larval and juvenile ecology, mechanisms thatdetermine recruitment, population size and vitalrates, interjurisdictional movements, and the effectsof anthropogenic activities present significantobstacles for managing paddlefish populations. Questions about the size and structure of localpopulations, and how such populations are affected bynavigation traffic, dams, and pollution are regardedas medium priority areas for future research. Theavailability of suitable spawning habitat and overallreproductive success in impounded rivers are unknownand represent critical areas for future research. Research on reproductive and recruitment success inimpounded rivers have significant implications formanaging paddlefish, as rivers are modified furtherfor human use.

MORPHOLOGICAL CHANGES OF A SMALL RIVER AFTER EXCAVATION OF THE MEANDERING LOW-FLOW CHANNEL

From river management point of view, it is important to forecast morphological behavior after river modification work such as straightening, widening and excavation. However, little is known about theinfluence of artificial impact on channel processes, especially in small rivers, because of lack of data. Therefore, in order to supply the information mentioned above, we investigated morphological changes after river channel improvement work in an actual river. In this paper, we deal with temporalchanges of bed configuration after excavation of the meandering low-flow channel which was carried out in the Yamamori River. By field survey, we examined the plan form variation of low-flow channel, the bed profile in the longitudinal direction and the grain-size distribution of bed materials. The significant difference of discharge, which is one of the main features of floods in small rivers, leads to considerably different morphological behaviors. This channel morphology was analyzed by the numerical model, and channel processes in the Yamamori River were explained on the basis of the numerical results.

Potential effects of a major navigation project (Paraguay-Paraná Hidrovía) on inundation in the Pantanal floodplains

The Pantanal wetland of Brazil, a vast complex of seasonally inundated floodplains along the Paraguay River, is renowned for its outstanding biological resources. A proposed navigation project known as the Paraguay–Parana Waterway (or Hidrovia) would deepen the Paraguay River channel to facilitate year-round navigation through the Pantanal. The possibility of decreases in river levels (stage) has aroused concerns in relation to the potential environmental impacts, however the poor understanding of the hydrological relationships between rivers and floodplains has hampered evaluation of these impacts. The present study evaluates the potential impact of river modifications on adjacent floodplains by examining the relationship between the Paraguay River stage and the extent of floodplain inundation. Satellite observations of flooded area (from passive microwave emission; monthly data for 1979–1987) are plotted against river stage from several stations throughout the region to show the stage–inundation relationships for eight subregions along the Paraguay River. Scenarios in which the Paraguay River stage is decreased from the 20th and 80th percentile values reveal large potential impacts on inundation. For stage decreases of 0.10 and 0.25 m, the total flooded area is reduced by 1430 and 3830 km2 at low-water, and by 2410 and 5790 km2 at high-water, respectively. The floodplains of the two northernmost subregions appear to be most susceptible to reductions in flooding, losing more than half of their flooded area with a 0.25-m decrease in the low-water stage. The ecological impacts of these reductions in flooded area may be particularly severe at low water, when the few areas that typically remain flooded throughout the dry season serve as important refuges for aquatic animals. These results underscore the need for better understanding of the hydrology of the integrated river floodplain systems in the Pantanal before river channel modifications are carried out. Copyright © 1999 John Wiley & Sons, Ltd.

Home Range and Seasonal Movements of the Turtle Graptemys flavimaculata

Home Range and Seasonal Movements of the Turtle Graptemys flavimaculata

The basic concepts of conservation of rivers and joint works for natural environment

The concepts of relationship between river modification and natural environment is defined. The habitats of rivers are consist of river space and water. River space are composed of bed materials, plants, river bank, facilities and so on. Water means water flow and water quality. Organisms use these habitats. It is important that we understand the human impacts (especially river modification) makes some changes of river habitats and grasping the relation between the impact and the response (habitat response).

Effects of river regulation and diversion on marine fish and invertebrates

AbstractThe effects of freshwater regulation and diversion on the adult and larval stages of fish and invertebrates in coastal marine waters are reviewed.Potential impacts of river modification are highlighted based on our present understanding of the role of fresh water on the physical, chemical and biological processes on the marine environment. These include effects on migration patterns, spawning habitat, species diversity, water quality and distribution and production of lower trophic levels. The effect of dams on anadromous and catadromous fish are also presented.We discuss in detail the marine response to specific river regulation projects on the Nile, Indus and rivers flowing into the Black Sea, San Francisco Bay and James Bay in Canada. A decline in some coastal fisheries with an overall negative impact on the biota is generally associated with reductions in freshwater flow.Extensive ecological considerations are needed during the planning stage of large‐scale freshwater modification projects to minimize potential impacts.

Impact of Stream Modification on Habitat Component and Fish in Tagawa River

Typical river modification methods were applied to the Tagawa River, Tochigi prefecture, Japan. A range of 1.25km was straightened and widened to reduce flooding.An investigation of the available habitat and the biota was made to grasp the biological effect of the modification. This study discusses the small river modification method to preserve the fish habitat. There are a few studies which observed a relationship between riparian habitat and change of fish for a stream modification in Japan.

River regulation in the United Kingdom: An historical perspective

AbstractThe beginnings of direct river modification in the U.K. are traced back to the 1st century A.D. when works were undertaken for land drainage and transportation. After the Roman period river works were widespread, there being more than 5,000 water‐mills by 1086, but of small scale until the 17th century. Impressive drainage schemes were supplemented from the end of the 18th century by the construction of numerous small dams for water supply and to provide compensation water. Severe pollution during the mid‐19th century led eventually to an organized system of river management. By 1900 the era of large dam buildings and large (> 1000 km) inter‐basin transfers had begun. The regulation of rivers in the U.K. has been subjected to much public scrutiny and debate, more so than the development of any other resource. However, the problems being encountered in river management today are shown to be embedded in the history of water resource development.