南水北调中线工程对汉江流域疾病流行的影响

本文在分析湖北省局部地区自然疫源变化及疾病趋势的基础上,指出了南水北调中线工程可能对地氟病、血吸虫、疟疫、乙脑及其它水源性疾病所带来的影响,并提出了建设性的建议和对策。     

APPLICATION OF LINEAR SYSTEM'S THEORY AND LINEAR PROGRAMMING TO GROUND WATER MANAGEMENT IN KANSAS1

ABSTRACT: A ground water management model based on the linear systems theory and the use of linear programming is formulated and solved. The model maximizes the total amount of pound water that can be pumped from the system subject to the physical capability of the system and institutional constraints. The results are compared With analytical and numerical solutions. Then, this model is applied to the Pawnee Valley area of south-central Kansas. The results of this application support the previous studies about the future ground water resources of the Valley. These results provide a guide for the ground water resources management of the area over the next ten years.     

RESERVOIR SEDIMENTATION AS A FUNCTION OF PRECIPITATION VARIABILITY1

ABSTRACT: This research examines what is hypothesized as a critical factor in reservoir sedimentation - precipitation variability. The coefficient of variation for annual precipitation, computed for the period relating to sedimentation, is regressed against sediment yields for several reservoirs over a wide range of environmental settings. A significant linear relationship results, and when precipitation variability is combined with several additional variables available from reservoir summary sheets, almost 83% of the total variation in sediment yield is accounted for. It is suggested that the coefficient of variation for annual precipitation fulfills a direct process role when modeling reservoir sedimentation much more effectively than annual precipitation or runoff.     

AN ARCHETYPAL LINEAR PROGRAMMING MODEL FOR OPTIMAL INTERTEMPORAL ALLOCATION OF GROUNDWATR TO AGRICULTURAL ACTIVITIES1

ABSTRACT: In the past, researchers have applied a variety of analytical techniques for maximizing the present value of a stock resource - simulation, calculus of variations, stochastic dynamic programming, and optimal control theory. This paper presents a more operational approach - linear programming. A simplified, broadly drawn example from Southwest agriculture is used for demonstrating the model's structure and output. The method is based on a set of state transformation operations that prevent the additivity assumption of linear programming from being violated.     

SOLID SET IRRIGATION SYSTEM DESIGN USING LINEAR PROGRAMMING1

: Irrigation systems can be formulated to enable linear programming to be used to obtain optimal systems. Linear programming is a readily available technique in most scientific and technical centers which have computer facilities. The objective function towards a minimal cost is based on a suggested classification of the system components, and the constraints mainly refer to required pressures and discharges. A case study in which linear programming is used to determine optimal pipe diameters is given for the solution of a solid set under tree sprinkler system.     

EFFICIENTLY REDUCING NONPOINT PHOSPHORUS LOADS TO LAKES AND RESERVOIRS1

ABSTRACT: Several problems that make it difficult to deal with water pollution from cropland are identified. The most immediate need is for a rational framework for determining where conservation programs can make an impact on eutrophication problems in reservoirs draining rural watersheds. This includes estimating the level of control that would be required for each local farm situation and the economic impacts for the planning area. A modeling approach is suggested for a planning area in Southeastern Pennsylvania.     

IRRIGATION PLANNING BASED ON WATER DEFICITS1

ABSTRACT: The deliberate underwatering of a larger land area, as practiced in Southern Asia, has provided impetus for a systematic investigation into the effects of designing projects for crop water deficits on Benefit-Cost performance. The study began with the derivation, from published experimental results, of functions relating ultimate crop yield to the magnitude and timing of water deficits, i.e., of the productivity of irrigation water. To obtain the net benefit of the project, the relation between the harvested area and output and the on-farm production costs was then suggested. The cost of supplying the irrigation water to the proposed area and of distributing and applying it to the field was determined, thus completing the Benefit-Cost equation. A computer simulation model was then established to search for the irrigation project design capacity and area to maximize the net present value in the Benefit-Cost analysis for the development proposed.     

PRIORITIZING WATER MANAGEMENT PROJECTS IN SOUTHEAST ASIA: AN EXPERIMENTAL METHODOLOGY

ABSTRACT: Southeast Asian nations with extensive water management systems have numerous candidate and ongoing programs and projects. They cannot possibly all be funded and implemented simultaneously in any serious way. Choices must be made. But how to select? What criteria can assist with the screening in an acceptable manner, particularly in the near absence of useful technical and economic information across them all. This paper suggests a methodology by which assessment criteria can be constructed which conforms to any given national information base and development needs. Criteria can be weighted one against the other in their relative importance. For each criterion a ranking scale puts the “best” (most, highest) at one end and the “worst” (least, lowest) at the other. Each candidate project is then subjected to these consistent assessment methods for a weighted “score.” Key criteria normally have surrogate measures depending on information available. Criteria are of three sorts: sheer volume, e.g., of a specific use, a benefit; ratios and relations, e.g., A as percent of B; and other more subjective criteria, e.g., regional or income distribution impacts. The basic criteria include, for example, time to full benefits (minimize), OM & R as percent of investment (minimize), and permanent rural jobs created (maximize).     

A rotational groups system approach for interdisciplinary research

Environmental research is characterized in each of its successive phases by a strong interdisciplinarity. A rotational groups system (RGS) method is proposed as an instrument to encourage interaction among researchers from fields that are traditionally far apart. Meetings conducted with the RGS procedure involve all the researchers, who, in repeated and topical encounters, are able to exchange information on a wide variety of environmental subjects. These meetings can be arranged according to a special calendar, through a series of phases treating different aspects of the same subjects to be discussed, and above all, referring to specific themes and working guidelines organized on the basis of criteria designed to favor an exchange of ideas and constructive discussion. At the end, the plenary assembly edits an overall resume of the proceedings, and votes on the final resolution, which brings together all the conclusive opinions regarding the themes discussed.     

OPTIMIZATION IN MUNICIPAL WATER SUPPLY SYSTEM DESIGN1

ABSTRACT. The design of a municipal water supply system may involve utilizing singly or in combination a conventional water supply, a desalted water supply, and a supply from a recharged aquifer reservoir. Optimization of the design requires a model formulated in a way that modern methods of systems analysis can be used. This study concerns the formulation, solution, and evaluation of a mathematical model of a municipal water supply system that includes a supply from a variable quality output desalting plant. The combined system is operated in conjunction with an artificially recharged aquifer reservoir. Also considered are short periods of water shortages. The model is set up in an approximate linear programming format, and the optimum solution (minimum cost) is found. The model is tested by applying it to the design of a supply system to meet the 1985 estimated water demand of the city of Lincoln, Nebraska. Results of this test indicate that the artificial reservoir and the existing conventional supply system are capable of supplying that demand during all but the peak period. An electrodialysis desalting system is used in this analysis. It is competitive only when the length of transmission pipeline for a conventional supply system approaches 90 miles. The model is formulated in a general way so that it can be applied to almost all situations encountered in municipal water supply design, as well as to the specific system designated for this study.