Hidrológiai Közlöny 1974 (54. évfolyam)

3-4. szám - Könyvismertetés

Hidrológiai Közlöny 1974. 3—4. sz. 153 conditions, the development of 3 sewage disposal regions is suggested in the area, namely 1 the Dunaszoros Region (Visegrád—Nagymaros) 2 the Szentendre Region, and 3 the Vác Region. In his paper on the role of farming techniques in water management M. Kamarás reviews the impact of farming on water uses. Of the natural factors, it is topography, contour and the meteorological elements, which together with soil conditions govern the possibilities and scope of agricultural production. Even where adverse conditions make farming difficult, advanced water management is always a necessity. Owing to the wide array of fertilizers available, the problem of nutrient restoration is diminishing in importance, so that water becomes increasingly the factor determining the crop yield. The problem of uniform distribution of irrigation water over sloping irrigation plots is considered by Cs. Kocsondi. The pressure difference along a lateral on sloping terrain is influenced besides friction primarily by the difference in elevation. Non uniformity in water application may result in erosion processes and in the poor utilization of irrigation water. A computer program was devised to study, the influence of contour for four different laterals and the percentage differences in the nozzle discharges were represented graphically. In general 2 to 3% was found to be the terrain slope at which the pressure distribution along the pipeline and, in turn, the uniformity of discharge is most favourable. The development of pumping plants for large sprinkler irrigation schemes built over the past 10 years in Hungary is reviewed by O. Röser. Attention is focussed here on the automation problems of mechanical pumping equipment. Reliable automatic operation was ensured by the application of vertical-shaft machines. This resulted in simplified automatic starting operations and in reduced space requirements. A still debated problem in pumping plant design is related to the superstructure. Besides the machine rooms built of conventional materials, namely reinforced concrete and brickwork such of plastic shell arches are also used. Under a domestic design competition at VIZITERV, several solutions have been submitted for advanced speed regulation. The experience gained in designing pumping stations provides the background enabling Hungary to actively participate in the standardization work now in progress under a COMECON agreement. Mechanization of maintenance and biotechnical works in earth canals is the subject considered by O. Mohos. Owing to the growing labour shortage a high degree of mechanization must be attained in maintaining the extensive canal network. Primary concern is devoted to the maintenance of drainage canals in the Hanság area in West-Hungary. In their paper Dr. M. Merényi and G. Pallós consider the problems of corrosion control for steel hydrotechnical structures. It is recalled that the fixed assets in the water sector attain the order of magnitude of 70 thousand million Ft, of which 20% are the technological and mechanical equipment that is exposed to the effect of corrosion. Up to 1980 the mounting of further 128 thousand metric tons of steel structures is envisaged. In the Corrosion Control Group, Contributions A. Kocsis (VIZITERV) It is necessary to point out that although engineering design is based on the concepts of long-term planning, it takes other solutions also into consideration, in accordance with the requirements of a particular situation and period. This does not imply that there would be a conflict between long-term planning and engnieering design, but their parallel functions are guarantees of development. Attention is called to the Water Sector, within the National Technical Development Commission the results of the 7-year long water exposure tests, plant- and pilot plant experiments, as well as the experience gained during several years of planning corrosion control measures for hydrotechnical steel structures were analysed and evaluated. It is emphasized to use always the control method which provides satisfactory protection in a particular location for a particular purpose. For hydrotechnical structures the potential solutions include metal coating systems, paint coating systems, and combined (metal + paint coating systems). The economics of corrosion control are also analysed. Cathodic protection is discussed in the paper „Application of active corrosion control in public utilities" by Gy. Váradi. Brief reference is made to the corrosion control solutions applied for long pipelines, distribution networks, diversion structures, steel tanks, sluices and drilled wells. Experience gained thus far has shown the cost of cathodic protection to amount to no more than 0.5 to 2% of the total first cost of the project. The problems with which designers of water projects are faced in the Democratic Republic of Vietnam are described by I. Takács. Water management has evolved on the basis of ancient customs, first of all to meet the demands of rice growing. Two crops per year are common. Owing to overpopulation, irrigation farming is necessary in hilly regions as well, the prerequisite for which is reservoir storage in the hills and mountains. Great difficulties are encountered as a consequence of largescale soil erosion resulting from deforestation for reclaiming new lands. Communal drinking water supply exists in the majdr town only, but even there only part of the population is served, mainly from public hydrants. The daily per capita consumption is from 20 to 70 litres. Water is obtained from deep drilled and dug wells, the majority of the latter being contaminated. Industrial water is obtained from surface waters. In accordance with the rainy seasons the streamflow in the rivers varies between very wide limits, e.g. the dry-weather flow in the Red River is 2000 cu.m/sec, while the flood discharge is up to 25—30 000 cu.m/sec. The range of stage fluctuations exceeds 10 m. The first steps towards the practical realization of water management have already been done. In their paper on water supply and sewerage problems in North-Africa and in the Near-East the authors L. Bardóczy, S. Szlávik and B. Wittinghoff conclude that such utilities have attained adequate development especially in the capitals and densely populated major towns. Water supply and sewerage are very low levels in the suburbs. The wastewaters are treated in few instances only. For improving supply it would be essential to introduce regular hydrological and hydrogeological research. In the developing countries the rapid growth of population makes the introduction of irrigation farming imperative, for which water management has the primary task of producing the water required. As a consequence of migration of the population into towns growing needs must be satisfied in water supply, sewerage and sewage treatment. to Section II. fact that in modern water management projects highly sophisticated technological equipment is used and construction assumes increasingly assembly-line character. Preparation and organisation call therefore for more comprehensive and detailed planning work. It is consequently also in the interest of the controlling authorities and the builders alike that adequate time be made available for designing while it is the responsibility of the designer to select the most advanced and most economical solution.