Relationship Between Circularity Ratio and Flood Hazard of Java Island’s Watershed

Watershed is a region inland that group on how the water flow, accumulate, and dischare based on its morphology. Every watershed has its morphometric parameter, and it might affect the flood frequency or hazard in the region. One of the parameters is the circularity ratio or Rc, the ratio of areas of a watershed and a circle with the same circumference/perimeter. There has not been any research that tries to compare the Rc and flood hazard on multiple watersheds. Here we try to calculate the Rc and flood hazard on multiple watersheds on the island of Java. The purpose is to find any correlation and pattern that can explain the rate of flooding using geometric and morphometric characteristics of the watershed. The watershed geometry is acquired from KLHK, and the flood hazard is generated from the Normalized Difference Flood Index (NDFI) of multi-temporal Sentinel-1 SAR Imagery. The result shows there are two patterns of relationship found on low (0 - 0.2) and high (0.6 - 0.8) Rc. These two groups show that higher Rc means a lower flood area but a higher flood hazard score. This pattern does not show up in the middle-value groups of Rc (0.2 - 0.6). Using other flood data or regions might show a different result. © 2024 SPIE.