Improving Spatial Rainfall Estimates at Mt. Merapi Area Using Radar-Rain Gauge Conditional Merging
Roby Hambali*,, Djoko Legono*, Rachmad Jayadi*, and Satoru Oishi**
*Department of Civil and Environmental Engineering, Universitas Gadjah Mada
Jl. Grafika No.2 Bulaksumur, Yogyakarta 55281, Indonesia
**Research Center for Urban Safety and Security, Kobe University, Hyogo, Japan
Rainfall monitoring is important for providing early warning of lahar flow around Mt. Merapi. The X-band multi-parameter radar developed to support these warning systems provides rainfall information with high spatial and temporal resolution. However, this method underestimates the rainfall compared with rain gauge measurements. Herein, we performed conditional radar-rain gauge merging to obtain the optimal rainfall value distribution. By using the cokriging interpolation method, kriged gauge rainfall, and kriged radar rainfall data were obtained, which were then combined with radar rainfall data to yield the adjusted spatial rainfall. Radar-rain gauge conditional merging with cokriging interpolation provided reasonably well-adjusted spatial rainfall pattern.
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