Abstract: Recession curve is a spesifc part of stream hygrograph after it reachs peak ﬂow and it represents the withdrawal of groundwater from storage. Daily recession constant of surface runoff, interﬂow, and baseﬂow have been derived for 15 segments on Goseng subwatershed with area approximately 596 ha.Semi logarithmic plot is recession analysis method which plotting stream discharge in y-ordinate and time in x-coordinate in semi logarithmic scale. The start of time recession is denoted by a straight line in the graphic. This method was used for separating a hydrograph into linear components of surface runoff, interﬂow, and baseﬂow. The results of the research shows that recession segment from daily hydrograph has short time and does not have all three stream components. A short segment can only be divided into two ﬂow components. Separation pattern for water catchment area are baseﬂow-interﬂow, baseﬂow-surface runoff, and interﬂow-surface runoff. Recession constant value differ from year to year but the differences do not have great inﬂuence in determining the average value of recession constant.
Keywords: surface runoff, interﬂow, base ﬂow, recession constant, semi logarithmic plot Diterima: 26 Agustus 2008; Disetujui: 3 Pebruari 2009
Penulis: Putu Sudira, Sukresno, dan Elly Kurniawati
Kode Jurnal: jppertaniandd090106