FLOOD FLOW PATTERN ANALYSIS ON SADAR RIVER DUE TO EMBANKMENT COLLAPSE USING HEC-RAS.

Flooding is one of the most frequent natural disasters in various places, including in the Sadar River located in Kedung Gempol Village. places, including in the Sadar River located in Kedung Gempol Village. Levee breaches, which are often caused by excessive water pressure, weak construction, or the age of the levee, can lead to major flooding, such as the that occurred in Kedung Gempol Village. The results of the 5-year, 10-year and 25-year return period discharge analysis years and 25 years are calculated using the Polygon Thiessen Method with the result of flood discharge at the 5-year return period amounted to 551.46 m3/s, 10-year return period amounted to 675.97 m3/s, and the 25-year return period amounted to 833.35 m3/s. Floods that downstream and upstream of the Sadar River showed very different characteristics at points 2 and 3, when the left side embankment broke. very different characteristics at points 2 and 3, when the left side embankment broke. At point 2, the
tends to be faster and has a larger water level,
while at point 3, the flood flow tends to be slower but has a larger inundation area.
inundation area.