ANALISIS DEBIT BANJIR RANCANGAN REHABILITASI SITU SIDOMUKTI

Sari

Sedimentation and hoarding by people has made the Situ Sidomukti shallow. Beside that, illegal occupancy has made change of land function to housing and agriculture. The purpose of the analysis of the Situ Sidomukti flood discharge rehabilitation design is primarily to evaluate several hydrological parameters, such as designated rainfall (intensity, duration, and frequency/IDF rain), time of concentration, run-off coefficient, recharge area, and flood discharge design. While the purpose of the flood discharge design analysis was to estimate of the flood discharge design at various timing (2, 5, 10, 25, 50, 100, and 1000 years), including its hydrographic form.

Due to the unavailability of data flow and considerably small data of recharge area, the analysis was conducted by using a rational equation: Q = C . I . A, where Q is the discharge, C is the run-off coefficient, I is the rainfall intensity, whereas A is the recharge area. The flood discharge design parameters are the designated rainfall (intensity, duration, and frequency/IDF rain), time of concentration, run-off coefficient, and recharge area.

According to the parameter above, Situ Sidomukti flood discharge time of occurance for 2, 5, 10, 25, 50, 100, and 1000 years are 20,72 m³/sec, 23,76 m³/sec, 25,35 m³/sec, 27,05 m³/sec, 28,14 m³/sec, 29,13 m³/sec, and 31,89 m³/sec respectively with triangle hydrographic form and the length of concentration time was 2,7 hours. These values should be evaluated againts existing volume/channel.

Keywords : Discharge, run-off coefficient, rainfall intensity, recharge area, return period.