ANALISIS DEFISIT DEBIT DAS MENGGUNAKAN METODE AMBANG BATAS (THRESHOLD LEVEL METHOD)

Abstract

Deficits discharge is an event that shows a lack of discharge on the river. This event causes by less rainfall event on the region. This study used threshold level method (TLM) to evaluate daily deficit discharge by comparing with the determined threshold level. The study conducted at 24 watersheds in East Java Region using historical data range from 1996 to 2001. In this study, a value of Q80 (percentile of 80th) from the data were used as a threshold level. Furthermore, all discharge data compared and evaluated by means of each Q80th values. The deficit discharge event was counted if the daily discharge was less than the Q90th values. Results showed that Q80 th value range from 0,01 m3/s up to 45 m3/s. The result also showed the spatial distribution of the deficit discharge qualitatively in East Java.