# Performance Evaluation of Rain-on-Grid Flood Simulations with a Collocated Co-kriging Reference in a Mamminasata Urban Watershed, Indonesia
> Nursaputra M.

URL kanonis: https://discover.unhas.ac.id/publications/pub_scopus_105036061009
Jurnal / Konferensi: Iop Conference Series Earth and Environmental Science
Tahun terbit: 2026
DOI: https://doi.org/10.1088/1755-1315/1607/1/012040
ISSN: 17551307
Citations: 0

## Authors
- Nursaputra M.

## Abstract
Abstract Land use change and intensifying extreme rainfall have increased flood risk in the Mamminasata metropolitan region, while flood depth information remains scarce. This study evaluates Rain-on-Grid (RoG) flood simulations using a reference depth surface constructed with Collocated Co-Kriging (CCoK) and develops an event-based hazard index for the 11 February 2025 event. RoG was driven by bias-corrected GPM IMERG rainfall, several digital elevation models (DEMs), and surface parameters derived from land cover. The CCoK-based reference surface in the Tallo Watershed was generated from field-surveyed flood depths and topographic covariates and outperformed IDW, ordinary kriging, and kriging with external drift, with RMSE = 0.491 m and MAE = 0.379 m (absolute error ≤ 0.5 m for 73.9% of flooded points). The RoG simulation using the enhanced DEM and calibrated Manning and Curve Number parameters achieved the best agreement with CCoK reference (POD of 0.86, RMSE of 0.57 m and MAE of 0.46 m) and reduced unrealistic extreme depths (max depth 6.54 m versus 9.91–21.81 m for the other DEM candidates). The hazard index that combines depth, depth multiplied by velocity, and duration reveals widespread shallow flooding and localized pockets of higher, long-lasting hazard on downstream floodplains. These findings indicate that integrating CCoK and RoG is suitable for model evaluation and event-based hazard mapping in data-scarce basins and can support disaster management and early warning for flood events.

## Keywords
- Flood myth
- Environmental science
- Flooding (psychology)
- 100-year flood
- Digital elevation model
- Watershed
- Hydrology (agriculture)
- Flood forecasting
- Kriging
- Flood warning
- Hydrological modelling
- Hazard
- Hazard analysis
- Mean squared error
- Warning system
- Elevation (ballistics)
- Meteorology
- Flood stage
- Return period
- Flood mitigation
- Index (typography)
- Metropolitan area
- Natural hazard
- Water level
- Hydrograph
- Early warning system
- HEC-HMS

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Sumber: Discover Unhas — RIMS Universitas Hasanuddin.
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