SPATIAL MODEL OF FLOOD HAZARD DUE TO LAND COVER CHANGE IN THE TARUSAN WATERSHED, WEST SUMATRA – INDONESIA

Abstract

Spatial modeling of flood hazards in the Tarusan Watershed of West Sumatra has the objectives of modeling land cover changes from 2019-2029-2039, flood numerical models, and hybrid spatial models of flood hazards. The methods used in this research are quantitative methods and field surveys to determine the accuracy of the modeling results. The results showed that land cover changes in the Tarusan Watershed experienced a decrease in land cover changes, namely primary forest and secondary forest land cover, while a land cover that experienced an increase in area was oil palm land cover and fields. The numerical model of flooding in the Tarusan Watershed shows that the peak of the flood (Qp) takes 3.12 hours, the time required to reduce the flood discharge (Tp+0.3) is which is 7.69 hours, and the time required to reduce the flood discharge (Tp+0.3+1.5T0.3) is 14.54 hours. The results of the hybrid spatial modeling of flood hazards in the Tarusan Watershed from 2019 to 2039 have undergone extensive changes. Changes in the area affected by floods from 2019 to 2029 are 323.91 ha, and changes (prediction) in the area affected by floods from 2029 to 2039 are 242.58 ha Land cover changes from 2019 to 2029 affect flood discharge by 5.65%, and land cover changes from 2029 to 2039 affect flood discharge by 8.55%. For flood disaster mitigation efforts, it is necessary to have information to the community living in the Tarusan Watershed that a flood disaster will occur if the rainfall intensity is more than 50 mm/hour with a duration of 1.11 hours, then the time needed to reach the peak of the flood is 3.12 hours, so that the community can anticipate the losses that will arise from the flood disaster.