RUKWA (sometimes also Rikwa and Hikwa)  , a shallow lake in German East Africa, lying 2650 ft. above the sea in a N.W. continuation of the rift-valley which contains Lake Nyasa . The sides of the valley here run in steep parallel walls 30 to 40 M. apart, from S.E. to N.W., leaving between them a level plain extending from about 71° to 81° S . This whole area was probably once covered by the lake, but this has shrunk so that the permanent water occupies only a space of 30 M. by 12 at the S. immediately under the E. escarpment . In the rains its extends some 40 M. farther N., and the north of the plain is likewise then covered with water to a depth of about 4 ft . The rest of the plain is a bare expanse intensely heated by the sun in the dry season, and forming a tract of foul mud near the lake shores . But in 1903–4 the level of the lake rose so that the waters covered the whole depression . The lake has two large feeders, one coming from the W., the other from the S.E . The W. feeder, the Saisi, or Momba, rises in 8o° 50' S., 310 30' E., and traverses a winding valley cut out of the high plateau between lakes Nyasa and Tanganyika . It enters the lake on its N.W. side . The other chief feeder, the Songwe, rises in 9° 8' S., 330 30' E. on the same plateau as the Saisi and flows N.W., entering Rukwa at its S. end . The Songwe is joined about 5o M. about its mouth by the Rupa, whose head-waters are in the high-lying land N.E. of Rukwa . The maximum depth of the lake is about roe ft .

Its water is very brackish and of a milky

colour from the mud stirred up by the wind . It contains great quantities of fish . First seen from the north by Joseph Thomson in 188o, it was visited by Dr Kaiser, a German, in 1882, and has since been thoroughly explored by various British and German travellers . See " Begleitworte zu der Karte der Gebiete am sudlichen Tanganjika- and Rukwa-See," by Paul Sprigade, in Mitteil. v . Forsch. u . Gelehrten a. d. deutschen Schutzgebieten (Berlin, 1904), with map on the scale of 1:500,000 .