FLOODPLAIN MANAGEMENT NEEDS PECULIAR TO ARID CLIMATES1

ABSTRACT: Many practices followed uniformly nationwide in the federal flood control and floodplain management programs are inappropriate or even counter productive in the arid Utah climate. An analysis of the 130-year Utah flood history, the structural and nonstructural flood programs in the state, and local perceptions obtained by field visits and interviews in 35 Utah communities revealed a number of such inefficiencies. Since flood flows dissipate quickly when they emerge from mountain watersheds onto desert lowlands, risks are concentrated near the apex of alluvial fans, include hazard from mud as well as water flow, and are compounded by canal interception of flood waters. Because of variation in the area flooded from one event to the next, floodplain mapping has tended to show risks too high in mapped areas and too low outside. Traditional channelization carries floods downstream past where they would dissipate naturally. The federal government needs to become more active in developing better flood hazard delineation and structural and nonstructural designs for arid areas. State government can help by providing a forum where communities can exchange experiences, reviewing structural designs prepared by local government, and providing local communities with technical expertise for dealing with federal agencies.     

NEW DIRECTIONS IN FLOODPLAIN MANAGEMENT1

ABSTRACT: Over the last 30 years, average annual riverine flood damages have exceed $2 billion. Damages associated with the Mississippi River Flood of 1993 exceeded $12 billion and these costs do not include the non-quantifiable, human impacts of this disaster. In a report submitted to the White House in June 1994, a federal interagency floodplain management review committee proposed better ways to manage the nation's floodplains. The committee indicated that the 1993 Mississippi River flood was the result of a significant hydrometeorological event, that federal flood control efforts in the Mississippi basin had prevented nearly $20 billion in potential damages, and that, in spite of federal flood damage reduction efforts, throughout the nation people and property remain at risk to inevitable future flooding. It recommended that the division of decision and cost-sharing responsibilities among federal, state and local governments be more clearly defined, and that the nation adopt a strategy of, sequentially, avoiding inappropriate use of the flood-plain, minimizing vulnerability to damage through both nonstruc-tural and structural means, and mitigating damages as they occur. The report did not call for abandonment of human use of the flood-plain but argued for full consideration of the economic, social and environmental costs and benefits of all future floodplain activity.     

FLOODPLAIN DELINEATION: AN ECONOMIC APPROACH1

ABSTRACT: Errors inherent in the conputation of water surface profiles are magnified by the shallow lateral slopes typical of most flood-plains, producing significant floodplain mapping errors. An economic optimization procedure which weighs the cost of overstating the location of a floodplain boundary against the cost of understanding the location provides a means for establishing the boundary location. In most cases the cost of overstating the boundary location exceeds the cost of understating the location by several magnitudes so that the boundary location should coincide with the minimum water surface elevation which would be expected to result from a flood of specified recurrence interval.     

FLOODPLAIN MANAGEMENT: SOME OBSERVATIONS ON THE CORPS OF ENGINEERS' ATTITUDES AND APPROACHES1

ABSTRACT: Methods of floodplain management are changing in the United States. There has been a gradual shift in emphasis from “flood control” to “management” of the floodplain. The complexities of multilevel governmental involvement in floodplain management demand an analysis of a new means to coordinate these efforts. It is the intent of this paper to discuss the role of the Corps of Engineers in this area and the problems the Corps has encountered in its endeavors. The occurrence of these problems indicates that there is a need to strengthen the federal role to ensure a comprehensive view of floodplain management.     

THE NEED FOR A COMPREHENSIVE APPROACH IN THE MANAGEMENT OF ENVIRONMENTAL RESOURCES1

ABSTRACT Environmental resources can be managed properly only by adopting a comprehensive approach. The whole environment must be considered as a single system, and prior to any action, all types of environmental impacts caused by it should be studied in detail. This paper underlines the close relationship between different environmental problems, analyzes existing management patterns, and proposes new alternatives whenever applicable. The different constraints, which have to be considered in the decision-making process while developing a plan, are also discussed. It is concluded that efforts neglecting the interaction among different aspects of the environment do not upgrade the quality of water, air, and land to any appreciable degree.     

A CRITICAL APPROACH TO THE CALIBRATION OF A WATERSHED MODEL1

ABSTRACT: A complex watershed-scale water quality simulation model, the Hydrological Simulation Program-FORTRAN (HSPF) model, was calibrated for a 16 km² catchment. The simulation step size was 0.33 hours with predicted and recorded hydrologic flows compared on an annual and monthly basis during a total calibration period of four years. Unguided numerical optimization when applied alone did not yield a model parameter set with acceptable predictive capability; instead, it was necessary to apply a critical process that included sensitivity analysis, numerical optimization, and testing of derived model parameter sets to evaluate their performance for periods other than those for which they were determined. Using this critical calibration process, the model was proven to have significant predictive capability. Numerical optimization is an aid for model calibration, but it must not be used blindly.     

ALTERNATIVE APPROACH TO THE FORMULATION OF BASIN HYDRAULIC GEOMETRY EQUATIONS1

ABSTRACT: Along a drainage network, there is a systematic variation of average flow parameters (width, depth, and velocity) at flows having the same flow duration. Hydraulic geometry equations mathematically express this interdependent relationship of stream-flow characteristics for a basin for annual flow durations varying from 10 to 90 percent. However, the equations proposed so far have had rather poor predictive performance for low flows. An independent investigation of the variation of discharge with drainage area and annual flow duration demonstrates a consistent relationship between these parameters. The relationship for the high to median-flow range differs, however, from that for the median— to low-flow range. The proposed equations provide a better predictive performance for low flows than previous formulations and a versatile means of estimating flow parameters for streams throughout a basin. The improved basin hydraulic geometry equations have a wide range of applications in areas such as stream habitat assessment, water quality modeling, channel design, and stream restoration projects.     

A LUMPED APPROACH TO THE INVERSE PROBLEM IN GROUND WATER HYDROLOGY1

ABSTRACT: A solution procedure to solve the inverse problem in ground water, based on lumped approach, has been proposed. The method has the following advantages: 1) exact determination of the boundary conditions and the physical laws of flow through porous media is not required; 2) all errors of approximation in describing the boundary conditions, physical laws, and the aquifer properties are lumped into the surrogate parameters; and 3) the same mathematical model can be employed both in the identification process and in the subsequent management studies. The optimal values of the surrogate parameters are found by using a multidimensional unconstrained optimization code devised by Powell. The solution procedure and the convergence characteristics of the proposed algorithm have been illustrated by two hypothetical problems.     

A REGIONAL APPROACH TO PROJECT EVALUATION1

ABSTRACT. Water and related land resource planning has generally been characterized by project evaluation in isolation. Feasible alternatives have been ignored because the economic analysis did not include the interdependence of such subregional and regional variables as factor and product prices and production possibilities. This paper presents an economic framework, consistent with a regional development objective and an efficiency criterion, for proposing and evaluating resource projects. Subregional and regional derived demand curves for water are developed under alternative assumptions of subregional competition, regional market restraints, and yield and price uncertainty. The derivation of water demand curves using the proposed regional framework as compared to sub regional isolation has the desirable properties of (1) a marginal analysis that is more flexible over time is substituted for a static average analysis; (2) range estimates incorporating probabilities are substituted for point estimates; (3) approximations to functional demand curves are substituted for “needs”; and (4) fewer resources are required to meet a regional market restraint.     

KNOWLEDGE UTILIZATION IN WATER MANAGEMENT IN THE NETHERLANDS RELATED TO DESICCATION1

ABSTRACT: The use of scientific knowledge in environmental policy making is an important topic. However, the relation between knowledge producers and policy makers is not a straightforward producer-user relationship. The development of a national desiccation policy in the Netherlands and the implementation of desiccation plans in local situations are used as a case study to investigate the knowledge policy relationship. Three theoretical explanations were used to analyze this case: a difference between the cultures of producers and users; a different rationality of the policy making and research processes; and processes of social construction of problem definitions which imply that different knowledge stocks are used depending on the framing of the policy problem. Emergence of the policy issue at the national level is demonstrated to develop in close interaction between knowledge producers and policy makers, while the interactions at the local level were more based on integration of expert knowledge through personal expertise and closely tied to the development of management plans. This case study thus reveals a difference between general knowledge supporting measures at the national policy level and the way in which specific knowledge is applied in local cases. Therefore more attention should be paid to the translation of policy problems from rather high levels of political authority to the conceptualization at lower management levels. A final conclusion is that knowledge use in Dutch desiccation policy can be understood by pointing to multiple theoretical perspectives. The rational actor model and a construc-tivist perspective turned out to be especially useful in explaining the different ways knowledge was used at the national and the local level.     

FLOODPLAIN STORAGE AND LAND USE ANALYSIS AT THE WOODLANDS,TEXAS1

ABSTRACT: The Woodlands, a totally planned community north of Houston, Texas, was studied in detail in an effort to develop a master drainage plan which minimizes adverse impact on the 100-year floodplain. A total of 40 HEC-1 and HEC-2 computer runs were made to evaluate various development, channelization, and reservoir storage options.     

A SYSTEMS RESOURCES APPROACH TO CITIZEN PARTICIPATION: THE CASE OF THE CORPS OF ENGINEERS1

ABSTRACT: The thesis of this paper is that the citizen participation process provides necessary, but not sufficient conditions to affect substantive change in federal water resource management agencies' planning and decisionmaking. That is, in its present form, the citizen participation process has been observed to occur outside of the normal decision arenas of federal resource management agencies. The paper reviews concepts of citizen participation and defines some theoretical problems inherent with them. Then, a strategy for the structuring of a citizen participation process is proposed. This strategy is based upon the notion that citizen support for federally sponsored programs are essential if such projects are to be implemented. Therefore, an approach which integrates citizen valves with those held by other institutions and the agency is suggested. In conclusion, the relevancy of actively developing and including citizen input to the water resource planning process is illustrated by a discussion of three cases of the Corps of Engineers and Urban Studies planning process, in different metropolitan regions.     

ONE APPROACH TO IRRIGATION MODELING UNDER RISK1

Recent progress in operations research has refined stochastic programming with recourse sufficiently to significantly increase its potential for use in water resource planning. To demonstrate its strengths and weaknesses this paper considers an irrigation planning problem and illustrates how more and more refined variants of this problem are successively cast into stochastic programming with recourse forms. The result is an outline of the state of the art with method limitations and demands on model formulation clearly indicated.     

A SURROGATE-PARAMETER APPROACH TO MODELING GROUNDWATER BASINS1

ABSTRACT: A surrrogate-prarmeter approach to modeling groundwater basins is presented, which has the following advantages over current simulation-type methods: (i) conducivness to modeling nonhomogeneous and nonisotropic basins; (ii) there is no need to guess boundary conditions if accurate information is not available; (iii) the model is amenable to systematic calibration or identification through the use of optimization techniques; and (iv) compatibility with systematic algorithms for analyzing a wide range of management strategies. Since the parameter identification problem is large-scale and nonconvex, it is decomposed through application of generalized duality theory, into several subproblems of smaller size which are solved independently a number of times in order to achieve an overall solution. Results are presented for a hypothetical system of four interacting wells.     

A STOCHASTIC DYNAMIC PROGRAMMING BASED APPROACH TO THE OPERATION OF A MULTI-RESERVOIR SYSTEM1

ABSTRACT: An heuristic iterative technique based upon stochastic dynamic programming is presented for the analysis of the operation of a three reservoir ‘Y’ shaped hydroelectric system. The technique is initiated using historical inflow data for the downstream reservoir. At each iteration the optimal policies for the downstream hydroelectric generating unit are used to provide relative weightings or targets for operation of upstream reservoirs. New input inflows to the downstream reservoir are then obtained by running the historical streamflow record through the optimal policies for the upstream reservoirs. These flows are then used to develop a new operating policy for the downstream reservoir and hence new targets for the upstream reservoirs. The process is continued until the operating policies for each reservoir provide the same overall system benefit for two successive iterations. Results obtained from the procedure are compared to the results obtained by historical operation of the system. The procedure is shown to develop operating policies which give benefits which are as close to the historical benefits as can be expected given the choice of the number of storage state variables.     

THE IMPACT OF FLOODPLAIN REGULATIONS ON RESIDENTIAL LAND VALUES IN OREGON1

ABSTRACT: The impact of floodplain regulations on mean appreciation rates of residential land values was tested at six study areas in five counties in western Oregon. The study hypothesis that such regulations significantly depress appreciation rates of regulated lands relative to those of similar unregulated lands was in most cases rejected. When the hypothesis was accepted circumstances would render conclusions tenuous. The problems and issues facing this type of research are presented in case studies of two of the research study areas. The following factors challenge investigators seeking to resolve questions about the relationship between land use regulations and land values: varying degrees of stringency with which regulations are enforced; unequal assessment procedures between counties; influences external to floodplain regulations that may affect appreciation rates, including denial of permits for septic tanks, flood damages, and amenity values associated with waterfront locations; and the uncertain effect that the availability of flood insurance, which accompanies floodplain regulations, has on land values.     

SELECTING RECONNAISSANCE STRATEGIES FOR FLOODPLAIN SURVEYS1

ABSTRACT: Multispectral aircraft and satellite data over the West Branch of the Susquehanna River were analyzed to evaluate potential contributions of remote sensing to floodplain surveys. Multispectral digital classifications of land cover features indicative of floodplain areas were used by interpreters to locate various floodprone area boundaries. The boundaries thus obtained were found to be more striking and continuous in the Landsat data than in the low altitude aircraft data. The digital approach permitted satellite results to be displayed at 1:24,000 scale and aircraft results at even larger scales. Results indicate that remote sensing techniques can delineate floodprone areas more easily in agricultural and limited development areas than in areas covered by a heavy forest canopy. At this time it appears that the remote sensing data would be best used as a form of preliminary planning information or as an internal check on previous or ongoing floodplain studies. In addition, the remote sensing techniques can assist in effectively monitoring floodplain activities after a community enters into the National Flood Insurance Program.     

AN IMPLICIT APPROACH TO PRICING AGRICULTURAL WATER TRANSFERS TO URBAN USES1

ABSTRACT: The increased agricultural efficiency of the American farmer has been a substantial impetus to this nation's rapid urbanization. In many western regions where total water supplies are limited, urbanization has required the transfer of heretofore agricultural water rights to the urban use. A major problem in such transfers has been the value or price of the water. A management level model of a typical urban water system was developed to optimize water supply, distribution, and wastewater treatment alternatives. The values of agricultural transfers were determined as the cost advantages of increasing allowable reuse levels of urban effluents which imply the use of a downstream right. This procedure is justified by the economic theory of alternative cost. Results for a test application to the Denver, Colorado area indicate values on the order of $1,000 per acre-foot of transferable water depending on effluent water quality restrictions and operational policies.