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2 River Basins and Coastal Systems: The Primary Domains of Integrated Water Resources Project Planning
Pages 23-62

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From page 23...
... However, water projects usually have more than one purpose, with impacts that cascade among factors and interactions that are often difficult to predict. The primary objectives of this chapter are to delineate the two major types of water resources systems (river basins and coastal systems)
From page 24...
... Water resources project planning that integrates the linkages among the physical, environmental, economic, and societal services of hydrologic systems requires a "systems" approach that is both multi-disciplinary and multi-jurisdictional. RIVER BASINS River basins define a well-established and widely accepted framework for designing and evaluating water resources projects (Loucks, 2003; NRC, 1999a,b)
From page 25...
... The river basin concept is a useful framework in which the mass balance of water, sediment, and associated geochemical constituents and their downstream fluxes provide a consistent basis for evaluating system components, their connections, and change. River basins can be divided into areas of erosion and transport in upstream reaches and transport and deposition in downstream reaches.
From page 26...
... The two systems are intricately interconnected; changes in discharge and sediment load upstream in the watershed are ultimately felt downstream in the coastal system. River basins serve many purposes such as water supply for domestic, industrial, and agricultural purposes; wildlife habitat; transportation and navigation; energy generation; and recreation.
From page 27...
... The nation's watersheds have been delineated by hydrologic units that are useful in planning water resources projects. During the 1970s, the U.S.
From page 28...
... Forest Service, Portland, Oregon. large-scale planning exercise -- to determine the most practical plan to control flooding along the Lower Mississippi River (Clarke and McCool, 1996)
From page 29...
... Understanding the Scope of Water Resource Projects: Examples from the Missouri and Mississippi River Basins Corps projects in the Missouri and Mississippi River basins illustrate the scale, scope, and type of water resources projects implemented by the Corps under numerous authorizations for flood damage reduction and navigation enhancement in the nation's large river basins. Although comprehensive in some aspects (e.g., hydrologic controls)
From page 30...
... restricted the formation and dynamics of river sandbars, which are crucial to spawning of 2Conversely, the UMRBA report cited the success of the Delaware River Basin Commission for its ability to develop strong, legally binding consensus among agencies involved in water resources management.
From page 31...
... . There is a need for a more integrated planning and management approach that acknowledges linkages between upstream and downstream parts of the basin as well as between various systems or components that make up the Missouri River Basin.
From page 32...
... Project is one of the most comprehensive Corps endeavors in inland waters. It involves flood control and navigation improvements in all four major river basins of the Lower Mississippi River Valley: St.
From page 33...
... The Mississippi River levee projects are designed to protect the alluvial valley against the projected flood by confining flow to the leveed channel, except where it enters the natural backwater areas or is diverted purposely into restricted floodways. The main stem levee system, comprised of levees, floodwalls, and various control structures, is 2,203 miles long (Figure 2-4)
From page 34...
... Army Corps of Engineers, Vicksburg, Mississippi.
From page 36...
... This case study discusses the Corps plans to build the Yazoo Backwater Pumping Plant in the Yazoo basin, one of the four river basins in the Lower Mississippi River Valley (Figure 2-5)
From page 37...
... 20) : Since the original authorization for Yazoo Backwater Protection, important hydraulic changes have taken place due to improvement of channel efficiency in the Mississippi River and to reservoirs and channel improve ments in the Yazoo Basin headwater area.
From page 38...
... The USFWS and the USEPA have both objected to the project as proposed in the draft reformulation report, and both agencies have recommended that nonstructural flood control measures be implemented rather than construction of the pumping plant. The USFWS has advised the Corps to enter into formal consultation, as prescribed under the Endangered Species Act, on the pondberry issue (USFWS, 2000c)
From page 39...
... Interest in developing a systems-level framework for water resources planning appears to be gaining appeal in some regions, especially as a tool to facilitate planning in interstate river basin systems. COASTAL SYSTEMS These case studies from the Missouri and Mississippi River basins demonstrate the complexity of planning and evaluating water projects at a variety of scales within geographically complex river basins.
From page 40...
... The challenge for water resource project planning and implementation in the coastal zone lies largely in developing the ability to consistently determine and account for the potential system-wide impacts of projects that may involve a single component of a system whose geographic definition may vary depending on the nature of its various components. Understanding this challenge and its complexity forms a significant theme for the following discussion.
From page 41...
... Conversely, water resource projects with a single coastal system stretching from southern New Jersey to North 3A recently completed report A Geospatial Framework for the Coastal Zone: National Needs for Coastal Mapping and Charting (NRC, 2004c) examined the spatial information requirements of the United States and its principal user groups and offered recommendations to improve the nation's mapping needs.
From page 42...
... The outer portion of a coastal system exchanges sediment with the inner coastal system, and the rates and locations of this exchange may be altered by water projects that modify sediment transport and deposition dynamics. River entrances and tidal inlets, whether natural, modified, or constructed, form a vital part of this sediment exchange system.
From page 43...
... Water development projects that have contributed substantially to coastal erosion on the U.S. Atlantic and Gulf of Mexico shorelines are generally those that prevent longshore sediment transport and those that trap sediment (e.g., building jetties, deepening navigation channels, disposing of dredged coastal sand in deep water)
From page 44...
... Recognition of the need for an integrated approach to coastal sediment management led the Corps to develop the Regional Sediment Management Program, a large research and demonstration program designed to promote more effective management of this valuable resource. The Inner Coastal System The inner coastal system consists of estuaries, interior shorelines, flats, and vegetated wetlands.
From page 45...
... Storage reservoirs can trap sediments and reduce the natural sediment load reaching inner coastal systems. Channelization and leveeing of coastal waterways can also reduce sediment supply to coastal systems by routing the sediment to deep water, as for the Mississippi River.
From page 46...
... Coastal Areas Corps projects in coastal areas illustrate the scale, scope, and type of water resources projects implemented by the Corps under numerous authorizations for addressing coastal erosion and navigation enhancement in the nation's coastal zone. These projects also illustrate the complexity of coastal systems and the need for an integrated approach to planning water projects.
From page 47...
... Section 111 of the 1968 Water Resources Development Act was written in response to concerns over erosion caused by the construction of similar entrances and authorizes "shoreline mitigation" projects. Erosion to the south of this entrance in the Town of Palm Beach resulted in the construction of a sand transfer plant in 1958 by state and local interests and in substantial beach nourishment (shown in Figure 2-6.)
From page 48...
... with the natural net southerly longshore sand transport and commenced eroding Assateague Island. Prior to the inlet formation, the City of Ocean City extended some distance south of its present location.
From page 49...
... Between the mid-1960s and 1988, the net loss of more than 150 km2 of seagrass cover in the lower Laguna Madre was attributed to reduced water clarity caused by maintenance dredging, and the species composition of the seagrass beds changed over another 190 km2 due to salinity changes associated with changed circulation patterns caused by the GIWW channel, which connected the upper and lower Laguna Madre in 1949 (Onuf, 1994; Quammen and Onuf, 1993)
From page 50...
... Onuf, "Seagrasses, dredging and light in Laguna Madres, Texas," 75-91[1994] , with permission of Elsevier Ltd., Oxford, United Kingdom)
From page 51...
... LINKAGES BETWEEN RIVER BASINS AND COASTAL SYSTEMS Terrestrial watersheds supply water, sediment, and nutrients to the coastal zone. Disruption in this flux, primarily from reservoir construction, impacts the physical and ecological characteristics of coastal systems.
From page 52...
... Terrestrial impacts on the coastal zone can be seen over a wide range of scales, from water quality and shoreline loss in the Gulf of Mexico, associated with agricultural practice and river regulation. in the MississippiMissouri-Ohio River system, to beach erosion and harbor siltation in many smaller coastal watersheds.
From page 53...
... in the north-central Gulf of Mexico to increased nutrient loading in the Mississippi River (Bratkovich et al., 1994; Dortch et al., 1994; Justic et al., 1993; Rabalais and Turner et al., 2001; Rabalais et al., 2002)
From page 54...
... Appropriate evaluation of project impacts requires an understanding of the broader system within which the project is placed. If the cumulative effects of reservoir and levee construction on Mississippi River sediment transport had been analyzed as part of the Mississippi River and Tributaries Project, wetland losses in the Mississippi deltaic plain could have been foreseen, allowing for the possibility of earlier and more effective mitigation.
From page 55...
... Because of the range of factors involved in evaluating modern water projects, it may often be necessary to evaluate different factors at different spatial and temporal scales. Spatial Scales for Water Resources Project Planning As some of the preceding case studies illustrate, water project activities can affect, for better or worse, hydrologic, ecological, and economic conditions beyond the immediate project area.
From page 56...
... Almost without exception, the watershed approach is endorsed by scientists, water planning experts, and the National Research Council (NRC, 1992, 1996, 2000, 2001a, 2002a) as the framework in which the physical and ecological aspects of water resources planning should occur.
From page 57...
... However, as the objectives of water resource projects have increased and as efforts to more fully account for the behavior of complex natural systems are made, sensitivity to temporal variation and the scale at which these variations takes place has become increasingly important. For water projects, the most significant factors whose time variability must be accounted for are those associated with climate.
From page 58...
... . Climatic changes of this nature have practical significance to water resource managers and numerous implications for the design of water resources projects.
From page 59...
... California's hydrology is extremely variable, involving multi-year droughts and short-duration extreme floods, and this variability increases the difficulty of water resources management. Regional water systems have been constructed to dampen the effects of droughts and floods on beneficial use.
From page 60...
... Planning for Continued Climate Change The changes in climate that are projected to occur during the next century could have a significant impact on the planning, design, and operation of water systems in the United States. Particularly, climate change could have a significant impact on river basin deltas and coastal regions.
From page 61...
... As growing awareness of the importance of coastal systems emerged, the Corps has attempted to incorporate greater understanding of these systems in water resource planning in the nation's coastal regions. However, as the nation's expectation for such projects has changed and greater emphasis has been placed on maintaining or restoring ecological function in the nation's river basin and coastal systems, the portfolio of water resource projects planned and implemented by the Corps has changed.
From page 62...
... 62 RIVER BASINS AND COASTAL SYSTEMS PLANNING and implementation efforts is a goal the Corps continues to pursue. The following chapters explore some of these concepts in greater detail and attempt to recommend how these goals may be achieved.


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