TIBERIS
the most important river of Central Italy. The importance of the site of the Palatine and of Rome is mainly due to its command of the crossing of the Tiber just below the island (see PONS SUBLICIUS), which must be of great antiquity, and was probably the only one in the whole lower course of the river.The derivation of the name is uncertain (Varro, RR iii. 16; LL v. 30; Serv. ad Aen. viii. 332), but its antiquity is vouched for by its appearance in the augural books (Cic. de nat. deor. iii. 20). It was also known as Albula, though it is incorrect to connect the name with albus (as Servius ad Aen. cit. and Festus 4 do). Hiilsen connects it with the Ligurian root ALB- or ALP-, meaning 'mountain,' so that Albula would mean the mountain stream (for a small stream of the same name in Picenum, see RE ii. 1331). Vergil (ib. viii. 64) calls it caeruleus, a colour which it not infrequently acquires when the blue sky is reflected in it; but its general and more approproate epithet is flavus (ib. vii. 31; Hor. Carm. i. 2. 13; ii. 3. 18).
It is a turbulent river and much subject to floods, which have always been a source of great danger to the city. No less than 132 inundations have been recorded (BC 1895, 283-300, for the mediaeval and Renaissance periods). Julius Caesar had a scheme for cutting a new channel a Ponte Mulvio secundum montes Vaticanos; see CAMPUS VATICANUS (Cic. ad Att. xiii. 33. 4; HJ 493-494).
The cura Tiberis under the republic was in the hands of the censors. Protecting walls were built at least as early as the second century B.C. (see CLOACA MAXIMA, and cf. BC 1889, 165-172; Mitt. 1889, 285), and we have nineteen of the terminal stones erected by P. Servilius Isauricus and M. Valerius Messalla in 54 B.C. (CIL vi. 31540 a.p, gives fifteen; and four more have since come to light (BC 1897, 62, 275; 1906, 117; NS 1896, 524; 1897, 10, 252; 1906, 207). All of them are given in CIL i². 766, a-t). They extend from the Pons Mulvius, at the second mile of the via Flaminia, downstream as far as the Almo on the left bank, while one was seen in the seventeenth century near S. Passera (opposite S. Paolo) on the right bank. On the other hand, it was the praetor urbanus who, a little earlier (the inscriptions are attributed to the time of Sulla), traced the boundary line between public and private property at Ostia (NS 1910, 554; YW 1911, 12; 1920, 89; Calza Ostia, 85).
The next termination was carried out by the consuls of 8 B.C., C. Asinius Gallus and C. Marcius Censorinus, and twenty of these cippi remain (CIL vi. 31541, a-u), and a third by Augustus himself in the following year, twenty-two cippi remaining (ib. 31542, a-w). In this termination the distance in a straight line r(ecta) r(egione) to the next cippus is given in feet, on the front, back or side (cf. CIL cit. p. 3110; see RIPA VEIENTANA).
In 15 A.D. a great inundation occurred, and the cura riparum was instituted by Tiberius (Tac. Ann. i. 76; Cass. Dio lvii. 4 ; Suet. Aug. 37 is mistaken; cf. Mommsen, RGDA2 29; BC 1894, 254-6; CIL p. 3109). The curatores, who were five in number, replaced several of the earlier cippi by new ones, adding to the original inscription the words curatores riparum qui primi fuerunt ex senatus consulto restituerunt. Their authority extended as far as Ostia, where one of their cippi and one of 24-37 A.D. have been found (NS 1921, 258-262; cf. CIL xiv. 192; YW 1922-3, 106). A little later on other curatores restored a part of the bank near the pons Cestius (CIL vi. 31543), and set up other cippi, three of which remain (31544 a-c -- before 24 A.D.). From the reign of Claudius we have a cippus of the curatores who 'ripam cippis positis terminaverunt a Trigario ad pontem Agrippae' (31545), while under Vespasian and afterwards only a single curator is named, it being doubtful whether one functioned for the whole collegium, or whether henceforth there was only a single curator (31546-8 -- 73-74 A.D.). We have other cippi under Trajan (31549-51 -- 101 and 104 A.D. -- seventeen set up by Ti. Julius Ferox curator alvei Tiberis ... ct cloacarum urbis), Hadrian (31552 -- 121 A.D.), Antoninus Pius (31553-4 -- 161 A.D.), Septimius Severus (31555-197 -- 198). None of these later groups is very large; and then there is a gap till Diocletian (31556 -- 286-305 A.D.).
See PONS AELIUS for the regulation of the channel there; and for the bridges, see PONS. For the termination and embankments in general, BC 1889, 165-172; 1893, 14-26; LR 9-13; Pl. 14-17, 75-77; PT 180. For the Tiber as a whole, see Nissen, Italische Landeskunde, i. 308-324; for floods in antiquity, Jord. i. I. 128, and in the Middle Ages, Gregorovius in Buonarroti, 1876, 313-321; 345-355.