Vízügyi Közlemények, 1958 (40. évfolyam)

4. füzet - VII. Kisebb közleménye

(80) the lo w parts of the catchment an inundation — storage — period no longer than the time of tolerance. The volume of surface water due to precipitation over small areas is obtained by Eq. (19) for a rainfall of 1 hour duration and an assumed drainage period of 1 day. Values i, respectively a are derived on basis of longprecipitation records and have been obtained from corresponding Hungarian standards. The runoff coefficient may be computed by the approximating relationship (17) wherein indices o, respectively n refer to values pertaining to irrigated, and unirrigated parts of area F. In case of large catchments an important part of which is irrigated, waterhousehold conditions may be governed by the late-spring and summer period; the characteristic runoff values arc determined from Eq. (20) on basis of functions according to Eq. (2), further by considering Eqs. (11) and (14). In deriving Eq. (20) a time of tolerance d — 1 day has been assumed. Coefficient a is computed by Eq. (17), while the time of concentration т is established by gage observations at the site. If, on the other hand, the irrigated area comprises but a small portion of the catchment and the winter and early-spring period may be considered significant as far as waterhousehold conditions are concerned, Eq. (21) may be derived on basis of functions according Lo Eqs. (6) and (13). In the former ß is the so-callcd irrigation coefficient allowing for effects of irrigation on waterhousehold conditions. Computations of this nature may be used for determining its value, although for conditions prevailing in Hungary fairly accurate assumptions can be made according to relationship (28) as well (Tables VII and VIII). In Eq. (21) the coefficient с may be obtained from Table IV, while the time of tolerance d may be taken as 7 to 14 days. The time of concentration т is established on basis of observations at the site. Excess water due to irrigation and to be disposed of is determined at the time irrigation plans arc prepared. Runoff volumes ensuing when rice-fields are dewatered are computed on basis of draining schedules prepared for harvesting according to Eq. (29). Compulation methods described in the foregoing can be utilized in designing main canals, laterals and collecting canals of drainage systems. Collecting ditches within irrigated fields are designed without any computation with a depth of 20 to 30 cm and a bottom width of 30 to 40 cm. Eqs. (20) and (21) apply to the dimensioning of mains and laterals, while Eqs. (19) and (29) lo that of collecting canals. The present paper is based on values characteristic for waterhousehold conditions in Hungary. The application of numerical results elsewhere would be erroneous. However, problems involving the draining of irrigated areas will everywhere yield to basic principles similar to those adopted for the method introduced. * * * The subject of this paper is identical with that of the report submitted by the author to the III. Congress of the International Commission on Irrigation and Drainage, 1957, San Francisco, The full text of the report in French is among the publications of the Congress (R. 7, Question 10). (Author's summary translated by Z. Szilvdssy c. eng.) BEZIEHUNGEN ZWISCHEN BEWÄSSERUNG UND ABLEITUNG DER OBERFLÄCHENWÄSSER von P. Salamin (Siehe Seite 452—482 des ungarischen Textes) DK. 626.86 : 626.82 Die Studie erörtert Herkunft und Menge der überschüssigen Oberflächenwässer des bewässerten Gebietes und gibteine kurzgefasste Übersicht der Entwurfsprinzipien der Entwässerungskanäle. Das überschüssige Oberflächenwasser der bewässerten Gebiete entstammt teilweise dem Niederschlag, teilweise unmittelbar der Bewässerung. Der Niederschlag ergibt auf bewässerten Gebieten mehr überschüssiges Wasser, als auf nicht