Vízügyi Közlemények, 1979 (61. évfolyam)

2. füzet - Déri József: Algéria vízgazdálkodásának sajátosságai és vízkészletének meghatározása

Algéria vízgazdálkodása 289 — data series were determined, or checked on the annual flows carried by the rivers, the normal annual rainfall depths over the catchment areas and the geomorpliological parameters of the catchments; — examinations have been extended to the length of the records on the river gages in Algeria, the distribution of gaging stations over various catchments, the density of the network, the magnitude of sub-catchments pertaining to the individual stations, the magnitude and proportion of areas investigated liydrologically and hydroclimatologically

; the representativity of maps indicating normal annual rainfall depths; the reliability of hydrogeomorphological parameters; — relationships have been established between the normal annual rainfall and the density of the drainage network, between the unit runoff and the density of the drainage network, finally the relationship between unit runoff and the normal annual rainfall over the catchment has been explored. For estimating the normal surface water resources in the catchment areas the author has formulated two new expressions using the data from 56 hydrological stations. The first of these expressions is applicable to catchments smaller than 1000 sq. km in size (with a correlation factor r = 0,95) A =0,915 p

2'

68

4 S°.842 The second is recommended for use in catchments larger than 1000 sq.km (with the very favourable r = 0,977 value) A = 0.31 p

3'

03

2 S

101

8 where A is the normal annual supply (10

6 m

3), P is the normal annual rainfall depth on the catchment (in metre units), S is the area of the catchment (sq.km). In order to facilitate practical computations the formulae have been plotted as two-variable charts ( Fig. 1 ). The new formulae were used l'or dimensioning valley-dam reservoir storage, further for estimating the surface water resources of Algeria. This was found to amount to round 10.9 thousand million cu.m. in a normal year and to be less by several orders of magnitude than the potential subsurface resources of the country. The extraordinary magnitude of catchments having no natural drainage is illustrated strikingly by the fact thai these form 94 per cent of the total territory of the country. Nevertheless, only 10 per cent of the surface water resources of Algeria originate in these undrained basins. In the coastal area along the Mediterranean the unit runoff reaches extremely high values, ranging from 5 to 10 litres/sec per square kilometre. In the undrained highlands this value decreases to 0.2 — 0.7 lit/sec per sq.km while only 0.1—0.001 values can be anticipated in the Sahara desert. * * * Caractéristiques (le l'économie hydraulique d'Algérie et determination de sa ressource cil eau Déri, József, ing. En Algérie, le développement de l'économie de l'eau se dirige de nos jours vers les territoire arides et semi-arides. Ne perdant jamais de vue cette circonstance, l'exploration du problème hydrologique sur place, ainsi que le développement de la méthode de calcul des ressources en eau ont été effectués par l'auteur et ses collaborateurs. En vue d'établir les bases de la recherche pour les nouvelles formules de calcul des ressources en eau