Kurva Lengkung Debit Aliran (Discharge Rating Curve) dan Karakteristik Debit Aliran Sungai Cidurian Kabupaten Serang, Provinsi Banten

Abstract

River discharge is an important hydrological parameters that are used as information for planning and management of a watershed. The continuous data of the river discharge is urgently needed to support planning and watershed management programs. The continuous river discharge data is obtained by converting the river water level to river discharge using the discharge rating curve. The objectives of this research are to establish the discharge rating curve of Cidurian River and to evaluate discharge characteristics of Cidurian River in the year of 2008-2012. The discharge rating curve established a model of power is used. The discharge rating curve has been established then is used to analyze the characteristics of Cidurian River discharge. The regression equation of discharge rating curve that has been established from the results of measurements of river water level and discharge in 1998-2010 that is Q = 9.79h1,35, which resulted the coefficient of determination (R2 ) of 0.85 and RSME (Root Mean Square Error) value that is equal to 0.28. The effective water level when there is no flow is 0.1 m, the equation must be adjusted and becomes: Q = 9.79(h+0.1)1.35. Because the highest the river water level data is used that 2 m, so the discharge rating curve is only valid is used to estimating the discharge at maximum the water level 2 m. Pattern of flow rate fluctuation for the five years (2008-2012) is quite extreme, particularly in the year of 2010 due to La Nina. Nevertheless, the highest flow rate occured in 2012 which is amounted of 145.96 m3/sec, while the lowest flow occurred in 2011 in the amount of 0.37 m3/sec. The highest monthly average discharge occurred in February (28.78 m3/sec), while the lowest monthly average discharge occurs in July (10.95 m3/sec). The highest ratio of maximum and minimum annual discharge was in the year 2012 (293.48), while the lowest occurred in 2009 (107.63). Cidurian watershed conditions in 2008-2011 categorized as moderate, while it is categorized as poor in the year of 2012. Total volume of flow occurred in 2010 that reached to 996.73 mm with coefficient of runoff was 0.43. While the lowest total volume of flow occurred in 2011 (443.32 mm) with a coefficient of runoff was 0.25.