tionship between them and the catchment areas. Such studies are given in [2] However,
accuracy of such determinations will be obviously lower as compared with that at
determination with application of mean moduli of maximum run-off. This is because of
the fact that the moduli obtained by several particular curves of the probability of exceeding
of maximum water discharges of the regional rivers whose parameters are
hardly to be established at short-term series of hydrological records are applied in the
relationships between the moduli of 1% of probability of exceeding and catchment area,
i.e. the calculated modulus of the maximum water discharge of 1% of probability of exceeding
contains obviously the error of development of the theoretical curve of probability
of exceeding..
It is impossible to conduct detailed analyses of the water discharges and volumes
of PMF (probable maximum flood) at this stage because numerous basic data required
for assessment of the PMP (probable maximum precipitation) [7] as the basis for the
PMF analysis are lack.
In this connection a transfer from maximum water discharge of 0.01% of probability
of exceeding calculated by stochastic determinations to PMF through coefficient
К=QPMF/Q0.01%=1.5 is used in the present report. With such ratio the maximum
PMF discharge of the Se Kong river at Se Kong 5 site will be as much as 19100 m3 /s.
Acceptability of such tentative assessment of PMF value is proved by comparison
of water discharges calculated by PMF method and by statistical methods conducted
by Hydrological Engineering Center, USA (by several USA water gauging stations
with long-term series of maximum water discharge records) [8]. As results from
the comparison the PMF values in many cases are either close or coincide with the design
ones of probability of exceeding 0,1 and 0,01% used in Russian practice for hydrological
validation of the hydraulic works of Classes I и II. However, in some cases the
difference may be considerable [8].
Position of the accepted tentative value of the maximum PMF discharge for the
Se Kong river (as the other calculated PMF values taken from [2] for some Laos rivers
in the Mekong river basin) in the field of the points of the curve (Fig. 3.2.8) establishing
relations between the PMF maximum calculated water discharges (moduli) and the
catchment areas [9] is not in principle in contradiction with tendency of bunching of
points and envelope of this curve. Position of the point of the moduli of the maximum