59
Kalu-oya at Caltura 841 300 72
Kalany Colombo 692 200 84
The Kaymel or
Mahaoya near Negombo 253 200 68
Dederoo-oya near Chilaw 38 700 70
----------------------------
4212 5100

[Footnote 1: See _ante_, p. 12, for a definition of what constitutes the
"mountain zone" of Ceylon.]

In addition to these, there are a number of large rivers which belong
entirely to the plains in the northern and south-eastern portions of the
island, the principal of which are the Arive and the Moderegam, which
flow into the Gulf of Manaar; the Kala-oya and the Kanda-lady, which
empty themselves into the Bay of Calpentyn; the Maniek or Kattragam, and
the Koombookgam, opposite to the Little Bass rocks and the Naveloor, the
Chadawak, and Arookgam, south of Batticaloa. The extent of country
drained by these latter streams is little short of thirteen thousand
square miles.

Very few of the rivers of Ceylon are navigable, and these only by canoes
and flat-bottomed paddy boats, which ascend some of the largest for
short distances, till impeded by the rapids, occasioned by rocks in the
lowest range of the hills. In this way the Niwalle at Matura can be
ascended for about fifteen miles, as far as Wellehara; the Kalu-ganga
can be traversed from Caltura to Ratnapoora; the Bentotte river for
sixteen miles to Pittagalla; and the Kalany from Colombo to the foot of
the mountains near Ambogammoa. The Mahawelli-ganga is navigable from
Trincomalie to within a short distance of Kanda[1]; and many of the
lesser streams, the Kirinde and Wellawey in the south, and the Kaymel,
the Dedroo-oya, and the Aripo river on the west of the island, are used
for short distances by boats.

[Footnote 1: For an account of the capabilities of the Mahawelli-ganga,
as regards navigation, see BROOKE'S _Report, Roy. Geog. Journ._ vol.
iii. p. 223. and _post_, Vol. II. p. 423.]

All these streams are liable, during the fury of the monsoons, to be
surcharged with rain till they overflow their banks, and spread in wide
inundations over the level country. On the subsidence of these waters,
the intense heat of the sun acting on the surface they leave deserted,
produces a noxious and fatal malaria. Hence the rivers of Ceylon presen