21G 
Note on the Bain-Fall in the Mahanuddy Basin. [No. 3, 
Note on the Bain-Fall in the Basin of the Biver Mahanuddy and the 
Floods consequent thereupon. — By Captain J. C. Harris, Bengal 
Fngineers. 
Communicated by Colonel Baird Smith. 
From any good Map of India it is easy to trace a general boundary 
line of the Basin of the Mahanuddy and having done so I find (from 
weighment of thick paper — cut to the required form) that it encloses 
an area of exactly 50,000 square miles made up of parts as follows : — 
Square Miles. 
Area of main Body of Basin 40,000 
„ „ neck of Delta 3,750 
„ „ Delta Proper 6,250 
Total area 50,000 
or acrain the area of the whole basin may be (roughly) divided into 
portions as below, the areas of which I shall have occasion to speak 
of separately, by and bye ; 
Square Miles. 
Area above the Delta 45,000 
„ in „ 5,000 
50,000 
Accepting the above as the area of the Mahanuddy Basin, I pur- 
pose considering here, first, whether the basin has any peculiarity 
either of size, form, position, or otherwise, which is pre-eminently 
calculated to produce excessive flood volume in the Mahanuddy ; 
secondly, whether theoretical calculations of flood volume, based on 
“ area of basin rainfall,” &c., &c., are corroborative or otherwise, of the 
calculations based on “ sectional area,” “ slope of bed,” &c., &c., which 
have been previously made by me. 
In respect of the first point offered for consideration, it appears 
above that the body of the basin has a mean diameter of 225 
miles ; that its centre is but 200 miles from the sea and its fur- 
thest limit little more than 300 miles from the same ; so that the 
size of the basin is such, that but a very moderately wide-spreading 
