HYDROLOGIC MODELING WITH REMOTELY SENSED DATABASES1

ABSTRACT: An integrated remotely sensed database was used as the basis for a hydrologic and sediment transport modeling effort for an agricultural area of western Puerto Rico. Classified spectral images of airborne radiance data provided ground cover information and were used in conjunction with topographic and soils data to guide model construction and provide input to the water balance and sediment yield simulations. Runoff and sediment discharge from hydrologically homogeneous regions were routed through the drainage network and combined at the basin outlet. The model was used to simulate four years of observed sediment discharge from the basin. Relative contributions to the total sediment yield of forested and agricultural areas were determined and compared.     

Evaluation of synthetic adsorbents for cleanup of herbicide-laden wastewater

Small-and large-scale farm operators and applicators urgently need user-friendly and cost-effective on-site methods to treat dilute-formulated herbicide-laden wastewater (i.e., rinsate). In this study, we investigated solvent-regenerable synthetic adsorbents, Ambersorb® 563 adsorbent, Ambersorb 572 adsorbent, and Ambersorb 575 adsorbent, as alternatives to activated carbon (Filtrasorb ® 400) for cleanup of water containing Dual 8E (a.i., metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide]) or Banvel 4L (a.i., dicamba [3,6-dichloro-2-methoxybenzoic acid]). Batch-type adsorption experiments were conducted to compare adsorptive capacities of the various adsorbents. Adsorption maxima, obtained from adsorption isotherms, indicated that of the Ambersorb adsorbents tested, Ambersorb 572 adsorbent generally exhibited the highest adsorptive capacities for the herbicides tested and was comparable to Filtrasorb 400. Solvent (methanol) regenerability studies demonstrated that herbicide was readily recovered from Ambersorb 572 adsorbent and Filtrasorb 400. In general, metolachlor was more readily recoverable than dicamba. In fixed-bed column studies, Ambersorb 572 adsorbent exhibited twice the adsorptive capacity of Filtrasorb 400. Fixed-bed columns were more effective in removing metolachlor from herbicide containing water regardless of the adsorbent used. Multicycling of Ambersorb 572 adsorbent resulted in 30% loss of adsorptive capacity for dicamba as Banvel 4L and no loss of adsorptive capacity for metolachlor as Dual 8E. Working capacity was reached after three adsorption-regeneration cycles. Fixed-bed columns packed with solvent-regenerable adsorbents may prove useful as part of an on-site wastewater disposal system.     

WATER QUALITY PREDICTION WITHIN AN INTERBASIN TRANSFER SYSTEM1

ABSTRACT A methodology for predicting the spatial and temporal levels of conservative water quality constituents within a multibasin water resource system is presented. Dissolved solids, sulfates, and chlorides are the constituents used during this investigation; however, any other conservative ion or mineral can be incorporated into the simulation model. The methodology is tested on the proposed Texas Water System. The water quality model, QNET-I, utilizes monthly canal and river flows and reservoir storage levels calculated by the Texas Water Development Board's systems simulation model. Discharge-concentration relationships are developed for each source of water in the system, including significant waste-water discharges. Reservoirs in the system are assumed to be completely mixed with respect to conservative constituents. A mass balance analysis is performed for each node and each month during the simulation period. The output from the water quality simulation is a table of the concentrations of the conservative water quality constituents at each demand point in the system and in each reservoir and canal for every month the system is in operation. The desired quality of the water at the demand locations is used to determine the economic utility of transporting and mixing water from various sources.     

SOME CONJUNCTIVE DESALTING STUDIES EN THE UNITED KINGDOM1

ABSTRACT .Operating rule procedures are developed for the optimal use of desalination in conjunction with surface water impoundments. Results obtained from the use of hill-climbing and dynamic programming methods are compared. Benefits to be obtained from the integrated use of desalination are demonstrated through a case study for the Barcelona area of Spain.     

NEW APPROACHES TO COMPREHENSIVE PLANNING IN CANADA1

ABSTRACT. In 1970, the Canadian Federal Government passed the Canada Water Act which provides for a co-operative federal-provincial approach to water resource management. The purpose of this paper is to outline our definition of comprehensive planning and the approach being taken under the new legislation. Two basic premises underly the definition. They are that resource management consists of an array of problems and that the prime function of planning is to provide information for decision making. The definition of comprehensive planning is embodied in a general statement and a set of principles. The principles define the approach that should be taken to provide adequate information for decision making in today's complex environment. A brief resume of the jurisdictions for water management in Canada leads to a discussion of a joint federal-provincial comprehensive study of the Qu'Appelle River Basin in Southern Saskatchewan. The basin and the study are described briefly. This is followed by an outline of the economic and social considerations which are being incorporated into the comprehensive planning study for the basin.     

REGIONAL WATER QUALITY MANAGEMENT GREAT MIAMI RIVER,OHIO1

The Miami Conservancy District was organized shortly after the disastrous flood of March 1913 to provide flood protection to municipalities along the Great Miami River. The District system is a classic solution which was entirely locally financed and is now operated and maintained by special benefit assessments on 45,000 parcels of property, 9 cities and 5 counties.     

STABILITY AND REACH LENGTH IN WATER SURFACE PROFILE DETERMINATION1

ABSTRACT: Extension of basic step methods of backwater computation to reaches of finite length is examined. Accuracies of commonly accepted hydraulic loss equations under particular water surface profile conditions are compared. Simulation of energy lines within a reach by parabolic curves is found to minimize error provided orientation of the axis of the parabola is selected in accordance with prevailing hydraulic conditions. Theoretical basis for an index reach length beyond which single-step computation from end to end of the reach must be in error is developed. Reduction of this reach length by suitable factors tailored to hydraulic conditions yields a mathematically defined allowable reach length for backwater computation. When reach length does not exceed this allowable reach length, no significant error may be detected. Automatic insertion of synthetic cross sections interpolated between surveyed cross sections when these are inadvertently spaced too far apart enables computation to proceed. This device is error-free for prismatic channls but may introduce error for irregular natural channels. Preliminary trials indicate that results so obtained may be accepted provided the fall in the original reach does not exceed from one to two feet. When this is exceeded, additional cross sections should be surveyed.