The
impacts of country development on the river runoff in term of runoff
depletion have well recognized by all concerned. However, the interest
of the degrees of the impacts both for the on-going and for future
appears to be little, if at all. In the case of the Chao Phya river for
Thailand, the real impacts had started since about 1975, gradually
became intensified towards 1994 and continuing at present. The fact that
the country development is kept progressing forward with an
acceleration, the water resources development works, which are among
essential components as a basic infrastructure, would have to be moving
in-line with that. The river runoff depletion would, therefore, become
the crucial concerned-problem.
The
findings from the reviews of the basic hydraulic data available indicate
the problem has been intensified to the degree that the responsible
agencies be on the alert.
In
the period between 1975 to 1994 (19-year) the annual runoff had been
depleted by 40%. At present, the annual runoff is available only at
15-20 Thousand million m3 against 30 Thousand million m3 , which had
been available in the past. The findings from the hydrological analyses
of 5 models including that of the double - mass Diagram of
rainfall-runoff all indicate that the acceleration of the depletion in
term of slope is about 1° per year2. If so, the Chao Phya river at
Nakornsawan possibly become dry-up in 20-30 years from now.
