VAAL, a river of South Africa, chief affluent of the Orange (q.v.). It rises at an elevation of over 5,00o ft. above the sea in the Drakenberg mountains, of the Transvaal, about 170 m. in a direct line west of Delagoa bay. It flows in a general S.W. direc tion, with a markedly winding course, across the plateau of inner South Africa, joining the Orange in 29° 3' S., 23° 36' E. The river valley is 500 m. long, the length of the river being 75o m.
The first considerable tributary is the Klip (8o m. long), which rises in the Drakenberg and flows N.W., its junction with the Vaal being in 27° S., 29° 6' E., 12 m. S.W. of Standerton. From this point to the eastern frontier of the Cape the Vaal forms the boundary between the Orange Free State and the Transvaal. The river is usually shallow and is fordable at many places, known as drifts. But after the heavy summer rains the stream attains a depth of 3o or more feet. At such times the banks, which are lined with willows and in places very steep, are inundated. As a rule little water is added to the Vaal by its tributaries. On the north the basin of the Vaal is contracted by the Witwatersrand and the Magaliesberg ranges, and its tributaries are few.
The Mooi rises in the Witwatersrand west of the Klip and, after running almost due S. 75 m., unites with the main stream about 90
m. below Vereeniging. In its course through Griqualand West, the Vaal flows in a wide rocky channel, with banks 3o ft. high, through an alluvial plain rendered famous in 1867-70 by the discovery of diamonds in the bed of the river and along its banks. The diamonds are washed out by the water and found amid debris of all kinds, frequently embedded in immense boulders. The last affluent of the Vaal, the Riet river, rises in the Beyers Bergen S.E. of Reddersburg and flows N.W. zoo m. through Orange Free State, being joined, a mile or two within the Cape frontier, by the Modder river (175 m.), which rises in the same district as the Riet but takes a more northerly course. The united Riet-Modder joins the Vaal 18 m. above the Orange confluence.
The name Vaal is a partial translation by the Dutch settlers of the Hottentot name of the river—Kai Gariep, properly Garib (yellow water) which refers to the clayey colour of the stream. The Transvaal is so named because the first white immigrants reached the country from the south by crossing the Vaal.