Hidrológiai Közlöny 1974 (54. évfolyam)

3-4. szám - Könyvismertetés

Hidrológiai Közlöny 1974. 3—4. sz. 150 the improvement of technology in water- and wastewater treatment, as well as at the perfection QF hydrotechnical construction methods. Of particular interest are the studies concerned with the influence of flow conditions in treatment structures on the efficiency of the technology applied. Systematical test runs were made to study the flow patterns in diverse types of basins involved in the technological processes of water- and wastewater treatment, as well as the seepage phenomena in open and closed filters. Inclusion of the results attained in the practice of designing will contribute to a higher treatment efficiency of communal structures. The role of cost-benefit analyses in designing water projects is considered by S. Orbán. The outstanding importance of cost-benefit studies in designing water projects is clearly appreciated, since besides construction-, maintenance- and repair costs, the projects may affect the waterhousehold in the environment, and in turn, the production in industry and agriculture, the biological balance in the environment, and even the sanitary situation. In connection with the realistic service life it is pointed out, correctly, that development has accelerated to an extent that technologies adopted for particular projects may become obsolate within a brief period of time. Service life is related to cost-benefit analyses by the fact that the social- and functional service life demands must be identified during the analysis. In this context reference is made to the remark made already in connection with technical regulation, namely that the contemplated service life of a structure is a fundamental parameter, which affects the margin of safety, which is related to the purpose of the project and thus — although necessarily involved in the cost-benefit analysis — its determination is first of all a problem of regulation. Some papers in the second group report on cnmnuter applications in the stage of preliminary studies, which yield more accurate criteria for the designer. The application of simulation techniques in preliminary studies is described bv I. Kontur. The obstacle to the spreading of simulation techniuqes was thus far the large volume of computation work involved. The advantages of such techniques become apparent first of all when applied to complicated, complex systems. The economic benefit increases not only as a result of more careful designing due to the greater number of alternatives considered, but also owing to the fact that in formulating the simulation algorithm, cases mav also be recognized which wou'd have remained undetected otherwise. The spreading application of computerized designing will prohabiv entail the introduction of simulation techniques in preliminary studies. An RC circuit analogue model was used for simulating the regional and local effects of several diversion alternatives in the work described bv Dr. F. Székelv. It is of snecial' interest to note that seeDage parameters, first of all transmissibilitv was optimalized bv a digital comrmter. avoiding thus the repeated costlv modification of the analogue model. The diversion alternatives were investigated bv the ana

1ogue mndel designed with the optimized parameters in a brief time and at little cost, so that this method became an efficient tool of designing. In the naner bv Mrs. Gillvin. Susan Salamin on the role of computers in nreliminarv studies a case is described where hesides a high-caoacitv computer a small computer was also used for processing hvdrological data. The latter was used for checking the correctness of the method envisaged. The problem of unwatering large construction nits Is considered bv I. Halász and J. Mantuanó. The method of dimensioning applied hv them lends itself to certain generalisations The narameters of anuifers having a great thickness arp difficult to determine hv means of partiallv nonptrating wells, as reflected hv thp inn to differences between the results obtained hv diverse formulae Owing to unreliable data the system is either overconservative, resulting in excessive costs or underdimensioned, which in extreme cases may prevent construction. For overcoming these difficulties the parameters involved in dimensioning were determined from the results of pumping tests performed at virtually steady conditions. A relation was established between the depth of wells and the parameters. When designing this method was used for determining the necessary well depth by successive approximation, together with the volume of water to be withdrawn. In this way an economical unwatering system was found for the duration of construction work. The design parameters were determined from the records of field tests, using the mean values and the standard deviation thereof, in accordance with the methods of mathematical statistics. The approach adopted is noteworthy, since — whilst higher accuracy in dimensioning is expected by many designers from the application of computers — the ambiguity due to uncertain basic data was eliminated by field tests, and the record was to mathematical analysis subjected subsequently. The dimensioning of reservoirs is considered by Professor Franke and his co-worker. Formerly, the volume of reservoirs was determined to balance the differences between natural discharge and demands, but dimensioning was based on the random series of discharges, rather than on the stochastic structure thereof. The latter can be grasped only with the help of probability theory and once the reservoir as a system is described by stochastic models and theories, the queing model proved most suited to describing the significant parameters of flow-through and storage processes. State probabilities and the cumulative distribution function of fullness were computed on the basis of the analogy between the queing problem and reservoir mechanics. In the method described the stochastic independence of inflows is assumed in simplification of the actual situation, which however, is considered permissible for practical applications. The method suggested by Gy. Bukovszky for estimating water balances appears promising enough to be introduced in designing practice. The role of reservoirs in the water balance is not sufficiently understood as vet. The suggestion has the purpose of eliminating the inconsistencies of the present water balances and serves thus the perfection of water resources management. This leads us to the third troun of papers in which applications of computer methods to designing problems in water management are described. E. Puky. in a naoer on the hydraulic analysis of rivers by means of electronic computer describes the programmes elaborated and used bv VIZITERV for the hydraulic studv of the Dráva River. The computer programs were devised to reveal the influence of levee distance on surface profiles and to examine different cases of backwater in a short time. Surface profiles were computed for each of 4 starting water levels and 12 discharge records. The development in the designing of distribution networks is analvzed by K. Bozóky-Szeszich and J. Derekas Exact designing has been made possible by advances in network theorv. but the application of these methods is impossible, unless a computer is available. Besides normal operation allowance can be made also for the effect of breakdowns. Computers were used for analysing the actual condition of a network to be expanded, and to everv case, where water is fed into the network at more than two point. The use of computers is desirable also for dimensioning regional distribution networks. Computerized cost estimation methods have also proved to be of advantage. The method in which the items of standard building costs are stored, leaving to the designer'to snecifv numerically the code and the volume Pertaining to the code, calls for laborious and careful preparatory work. A method has been developed in which the designer is relieved of estimating work volumes and of determining the codes.