Hydrological analysis of moveable weir planning for tidal flood handling in Cilacap, Central Java

Abstract

Abstract Global warming resulting in climate change has become a new disaster in the world. One of the changes in climate is the rise of sea water to land surface, which causes tidal flooding. One area that experienced tidal flooding was Kawunganten District, Cilacap, Central Java Province. The area is traversed by the Parit River with the river estuary located in Ujungmanik Village. The problem of tidal flooding in Kawunganten District can be overcome by constructing a moveable weir in the estuary of the Parit River. In planning on the moveable weir, a hydrological analysis is needed to determine the flood discharge plan. Rainfall data used as a basis for calculation of flood discharge at the study site is rainfall data from 3 observation stations namely Cilacap Station, Majenang Station and Ujungbarang Station with the recording period from 2009 to 2018. Calculation of rainfall plan is done using the Pearson Log Method III with a value of T100 = 165.463 mm. The results of the calculation of the flood discharge plan with the haspers method Q100 = 280.989 m3/sec, while the weduwen method Q100 = 132.804 m3/sec and the HSS Nakayasu method Q100 = 102.444. Furthermore, an analysis of tides on the coast of Cilacap Regency with the results of MWL (Mean Water Level) = 110 cm, LWL (Low Water Level) = 20 cm, HWL (High Water Level) = 220 cm.