Analysis of Secular Changes in the Hydrological Characteristics of a Small Forested Watershed using a Baseflow Recession Curve

Abstract

Long-term changes in the hydrological characteristics of a small forest watershed were examined using a master baseflow recession curve and the measured rainfall-runoff data from the experimental forest watershed in the measured years 2003-2011. The results of the study showed that the recession coefficient of direct runoff was lower than that of baseflow. In small forested watershed, the direct flow was lower than that of large scale watershed, flow due to its shorter period of occurrence. And baseflow was similar to large scale watershed's. A regression equation y = 0.7528e.8938, range 0.3~0.8 mm) was obtained using the master baseflow recession curve for the study period and the recession coefficient was calculated as K = 0.978. Changes between master baseflow recession curve and runoff showed great association and relevance such as increasing runoff was associated with the gentle slope of master baseflow recession curve and decreasing runoff was associated with the slope of master baseflow recession curve contrary. In the later years of the study period, the slope of the master baseflow recession curve appreciably became more gentle due to increases in baseflow. This suggests that the forested experimental watershed exhibit improved structural functioning of normal flood control and reduced occurrence of water shortage problems.

Applicability Assessment of Estimation Methods for Baseflow Recession Constants in Small Forest Catchments

“…The matching strip method (MS) estimates the master recession curve by plotting all the recession curves in a semi-logarithmic graph [4,25]. Recession curves are added and moved Figure 2.…”

“…The matching strip method (MS) estimates the master recession curve by plotting all the recession curves in a semi-logarithmic graph [4,25]. Recession curves are added and moved horizontally until the master baseflow recession curve includes most of the recession curves' tail ends [10].…”