Flood risk mapping of Bengawan Solo river in east java using the analytic hierarchy process and head/tails break classification

In Indonesia, it is recorded that there are 5,590 main rivers and 600 rivers have the potential to cause flooding among others. Bengawan Solo river is the longest river in Java, which always floods every year. The floods that hit the area have resulted in disruption of public health, disrupted economic activity, and damaged urban infrastructure. Early warning information is needed by the community to face the danger of flooding. In this study, we develop a decision support system for disaster risk assessment using the analytic hierarchy process (AHP). This system produces a risk map with marked regions divided into three levels of risk, low, medium and high using head/tails break classification. The object of research is focused on 36 sub-districts through which the river streams of Bengawan Solo in East Java. Results of evaluation of the level of risk of disaster with AHP — Head/tails break has a value of 69.44% accuracy.