Applying Google Earth Engine to Support Flood Policy Decisions in Makassar City
Andi Besse Rimba 1,* , Andi Arumansawang 2 , I Putu Wira Utama 3,4 , Saroj Kumar Chapagain 5 , Made Nia Bunga 4,6, Geetha Mohan 7 , Kuncoro Teguh Setiawan 8 and Takahiro Osawa 9

1. JICA Ogata Research Institute, Shinjuku, Tokyo, Japan
2. Karya Alam Selaras Ltd., Citra Land, Jl. Talassa City Block 37 A Kapasa, Makassar 90245, Indonesia
3. Development Planning Agency of Bali Province, Jl. Cok Agung Tresna, Sumerta Kelod, Denpasar City 80239, Indonesia
4. Doctoral Program of Environmental Science, Udayana University, Jl. P.B. Sudirman Denpasar, Bali 80114, Indonesia
5. Institute for Integrated Management of Material Fluxes and of Resources (UNU-FLORES), United Nations University, Ammonstrasse 74, 01067 Dresden, Germany
6. Fisheries Faculty, The University of 45 Mataram, Jl. Imam Bonjol No. 45 Cakranegara, Mataram City 83239, Indonesia
7. Global Research Centre for Advanced Sustainability Science (GRASS), University of Toyama, 3190 Gofuku, Toyama City 930-8555, Japan
8. Research Center for Remote Sensing, BRIN, Jl. Raya Jakarta Bogor Km 46, Cibinong, Bogor 16911, Indonesia
9. Center for Remote and Application of Satellite Remote Sensing, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan

Abstract

Makassar City frequently experiences monsoonal floods, typical of a tropical city in Indonesia. However, there is no high-accuracy flood map for flood inundation. Examining the flood inundation area would help to provide a suitable flood policy. Hence, the study utilizes multiple satellite data sources on a cloud-based platform, integrating the physical factors of a flood (i.e., land use data and digital elevation model-DEM-data) with the local government^s urban land use plan and existing drainage networks. The research aims to map the inundation area, identify the most vulnerable land cover, slope, and elevation, and assess the efficiency of Makassar^s drainage system and urban land use plan. The study reveals that an uncoordinated drainage system in the Tamalanrea, Biringkanaya, and Manggala sub-districts results in severe flooding, encompassing a total area of 35.28 km2 . The most affected land use type is cultivation land, constituting approximately 43.5% of the flooded area. Furthermore, 82.26% of the urban land use plan, covering 29.02 km2 , is submerged. It is imperative for the local government and stakeholders to prioritize the enhancement of drainage systems and urban land use plans, particularly in low-lying and densely populated regions.

Keywords: flood policy- flood map- inundation map- Makassar City- Indonesia- urban land use planning- satellite imagery

Topic: Topic D: Geospatial Data Integration