Annual Runoff Estimation from Stream Network Properties

Abstract

Stream network characteristics of a watershed can be taken as a long-term effect of the hydrological processes of rainfall and runoff within the watershed. It is, therefore, reasonable to expect some relationships between the watershed runoff and its stream network properties such as length of the main stream, total length of streams, cross-sectional area of the main stream, stream density and watershed area. Analyses of data obtained from nine representative watersheds of Northeast Thailand yield the following summary.

The stream network properties, such as the average length of main stream, total length of streams, and cross-sectional area of the main stream are closely related to the stream order (u) in general form as x=ab^u (r>0.95). The watershed area (A) is also related to the length of main stream (L_m), the total length of stream (L_s), and the cross-sectional area of main stream (C) in general form as A= cx^d (r>0.85). Such inter-relationships indicate the causality nature of the formation processes of stream networks within a watershed. The average annual runoff (Q) is found to have good relationships with A,L_m, and C (r>0.80).