摘要:

Voting behavior in a flood control referendum in Roanoke, Virginia, provides evidence that people living and working outside the flood prone area are willing to pay for flood control project construction. This voting behavior supports the argument that flood control benefits exist at the community level. In providing the cost sharing required under recent federal legislation, local government financing which distributes project costs over the whole population of a local jurisdiction, and not just those persons living or working in protected areas, may increase both economic efficiency and expand communities' financial capacity to pay for such projects.

ISSN:0043-1397    

DOI:10.1029/91WR03132

年代:1992

数据来源: WILEY

摘要:

Riparian resources include the borders of rivers, lakes, ponds, and potholes. These border areas are very important for a number of reasons, including stream channel maintenance, flood control, aesthetics, erosion control, fish and wildlife habitat, recreation, and water quality maintenance. These diverse functions are not well protected by law or policy. We reviewed law and policies regarding endangered species habitat designation, land use planning, grazing management, water allocation, takings, and federal permits and licenses, along with the roles of federal, state, and local governments. We discuss the politics of implementing these policies, focusing on the difficulties in changing entrenched water and land use practices. Our review indicates a lack of direct attention to riparian ecosystem issues in almost all environmental and land use programs at every level of government. Protection of riparian resource values requires a means to integrate existing programs to focus on riparian zones.

ISSN:0043-1397    

DOI:10.1029/91WR03133

年代:1992

数据来源: WILEY

摘要:

Many studies have been carried out regarding the development of optimum operating policies for multiple reservoir systems but few of these have considered water quality as an objective. This study considers operations of the headworks system for Adelaide, Australia. The system is rather unusual because of its high salt concentrations which impose large economic costs on the consumers. In addition, a significant fraction of the supply is pumped from a distant river. An existing linear programming model for operation of the Adelaide system is modified to identify policies which minimize total system costs (including salt damage costs). These changed procedures can reduce the average salinity of the supplied water significantly but at some increase in annual pumping costs. The benefit‐cost ratio of the changes is estimated to be 3.0 for the entire syste

ISSN:0043-1397    

DOI:10.1029/91WR02687

年代:1992

数据来源: WILEY

摘要:

In optimization of any hydro plant system, the analysis should make use of all information available, including a thorough study of streamflow and civil engineering and electromechanical cost effectiveness. For this purpose a general mathematical model is used for an overall design optimization of run‐of‐river power plants. The design criteria for such power plants are fundamentally based on some important and critical cost‐effective parameters such as discharge design, penstock or tunnel diameter, turbine capacity, number of units and type of turbines. The optimization process consists of three main steps: (1) find the maximum yearly energy; (2) maximize the yearly benefits of all the maximized sets of power plants; and (3) select the most beneficial of the feasible sets of run‐of‐river power plants on the basis of a combination of the cited criteria. The computational analysis is based upon two major objective functions and a computer program which is developed for fast maximization and optimization of the generated

ISSN:0043-1397    

DOI:10.1029/91WR02528

年代:1992

数据来源: WILEY

摘要:

A revised model for the interaction of water flow, bed topography, and the rate and mean grain size of bed load in river bends is presented and compared with a large range of observational data. The model represents a modification of the approaches used by F. Engelund, J. S. Bridge, G. Parker, S. Ikeda, and coworkers. Model predictions generally agree with data from the River South Esk, Muddy Creek, River Dommel, and Hooke's laboratory channel. This simple model apparently performs at least as well as more complicated flow models. To make further improvements it is necessary to more accurately specify the interaction between local bed shear stress, sediment transport, and the local bed configuration.

ISSN:0043-1397    

DOI:10.1029/91WR03088

年代:1992

数据来源: WILEY

摘要:

The successful application of a conceptual rainfall‐runoff (CRR) model depends on how well it is calibrated. Despite the popularity of CRR models, reports in the literature indicate that it is typically difficult, if not impossible, to obtain unique optimal values for their parameters using automatic calibration methods. Unless the best set of parameters associated with a given calibration data set can be found, it is difficult to determine how sensitive the parameter estimates (and hence the model forecasts) are to factors such as input and output data error, model error, quantity and quality of data, objective function used, and so on. Results are presented that establish clearly the nature of the multiple optima problem for the research CRR model SIXPAR. These results suggest that the CRR model optimization problem is more difficult than had been previously thought and that currently used local search procedures have a very low probability of successfully finding the optimal parameter sets. Next, the performance of three existing global search procedures are evaluated on the model SIXPAR. Finally, a powerful new global optimization procedure is presented, entitled the shuffled complex evolution (SCE‐UA) method, which was able to consistently locate the global optimum of the SIXPAR model, and appears to be capable of efficiently and effectively solving the CRR model optimization prob

ISSN:0043-1397    

DOI:10.1029/91WR02985

年代:1992

数据来源: WILEY

摘要:

Solute transport through heterogeneous formations is modeled by the travel time approach, i.e., the time τ it takes a solute particle to travel from the source to a control plane. Due to uncertainty τ is a random variable characterized by its cumulative probability density function G(τ). This function is used by regulatory agencies in pollution site assessment. The main aim of the present study is to examine the impact of data, namely measured transmissivities, upon G(τ) and reduction of uncertainty. This is achieved for two‐dimensional steady flow of average uniform head gradient by using a Lagrangian approach developed in the past (Dagan, 1982, 1984, 1989; Rubin, 1990, 1991). The impact of data is seen in conditioning on measured values and in estimation of parameters characterizing flow and formation properties. The approach is illustrated by a simulation based on synthetic data. The results show how uncertainty is reduced by increasing the density of measurements for a control plane sufficiently far from the s

ISSN:0043-1397    

DOI:10.1029/91WR02759

年代:1992

数据来源: WILEY

摘要:

Time‐dependent quasi‐linearized infiltration with constant diffusivity from an axisymmetric shallow flat pond into a homogeneous semi‐infinite porous medium is investigated. Use of the Laplace transform reduces the equation to a form that can be solved using the boundary element method and inverted without difficulty. Previous attacks on this problem have been limited to solutions for large time because of the lack of a closed form expression for the axisymmetric free space Green's function. Here an alternative technique for evaluating the axisymmetric free space Green's function is presented, which enables solutions to be obtained at any time. Time‐varying fluxes are presented for a range of cavity sizes. The numerical results for small time match those predicted from one‐dimensional infiltration models, while the large time results approach the appropriate steady state values. The detailed numerical results indicate that approximate analytic results for fluxes from buried sources can be extended to include the shallow flat pond. This, together with earlier approximations for steady state fluxes, allows the flux from a shallow flat pond to be simply estimated at

ISSN:0043-1397    

DOI:10.1029/91WR03032

年代:1992

数据来源: WILEY

摘要:

A zero‐dimensional (lumped), linear conceptual model of the subsurface storm flow from hillslopes has been developed by integrating, over the length of the hillslope, the linearized one‐dimensional (Dupuit‐Forchheimer approximation) discharge relationship for saturated flow over an inclined plane. The derived two‐term storage function accounts for gravity‐ and gradient‐driven flow. Coupled with the storage balance equation for the plane, the model allows direct, analytical computation of the outflow hydrograph at the foot of the hill in response to an infiltration step input. The model is the conceptual counterpart of the linear advection‐diffusion (LAD) flow equation derived from the extended Boussinesq equation through linearization. In contrast to the kinematic wave approximation, the outflows normalized by their equilibrium values are properly given as functions of the infiltration rate. The outflow hydrographs computed by the conceptual LAD model approximate nonlinear behavior closely over a wide range of conditions encountered in field

ISSN:0043-1397    

DOI:10.1029/91WR03140

年代:1992

数据来源: WILEY

摘要:

An optimal maintenance‐related decision‐making problem is investigated in this paper for deteriorating water distribution systems. A semi‐Markovian model is developed to capture the dynamic evolution of the failure mode of a deteriorating main pipe, thus facilitating the determination of the optimal replacement/repair decision at various deteriorating stages. An example problem is solved to demonstrate the proposed methodology and to show the trade‐off between the system's availability and the expected maintenan

ISSN:0043-1397    

DOI:10.1029/91WR03035

年代:1992

数据来源: WILEY