Table12
Discharge at Rhondia Area inundated
(thousand cusecs) (square miles)
150 360
200 386
250 405
300 423
400 454
500 479
600 500
Source: Report of the Committee for the Augmentation of Water Resources of Damodar
Valley Corporation (Calcutta, 1959) p.52.
A linear regression y = a + ßx was fitted to the data by the standard least-squares method
and gave the following results :
a = 324 930
ß = 0.305
r^2 =0.944
r v 5
t = ---------- = 9.215.
v 1- r^2
The function = y = 324.93 + 0.305x
Was used for calculating the area inundated, y, for a given discharge, x. (See above for
the derivation of this equation. The relationship between the theoretical and observed
values suggested that a linear regression was justified.)
To calculate the damage per unit of is inundated, we made the same assumptions that
were used by the D.V.C. in computing their own estimates of flood damage, namely:
a) The intensity of cultivation is 80 per cent.
b) Paddy is the only crop grown
c) The average yield of paddy is 2056 Ib per acre
d) The average price of paddy is Rs.0.18 per Ib.The probability distribution of the peak flow together with the discharge/flood-damage
relationship enable the gross benefit of flood-control policies as described to be
computed. For this purpose, the maximum of average daily discharges measure of the
peak flow was used, since this appeared to be the concept of most closely related to the
data of Table 12, from which the linear regression of the area inundated on flood
discharge was computed.