Analisis Hujan Wilayah dengan Metode Poligon Thiessen dan Isohiet di Kabupaten Bantul Menggunakan Software Qgis dan Ms Access

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Indonesia is a tropical country which has quite high rainfall. Based on data released by the National Disaster Management Agency (BNPB) during the period 1815-2019, Indonesia experienced a total of 6833 floods or about 33.5% of all types of natural disasters, one of the areas affected by the flood was Bantul Regency. Bantul Regency is a district in Yogyakarta Province. In 2019, Bantul Regency was the area most affected by floods and landslides in Yogyakarta Province. This study aims to determine the amount of regional rainfall using the Polygon Thiessen and Isohyet methods in Bantul Regency.

 The analysis of lost rain data was calculated using the Inversed Distance Squared method. Analysis of regional rainfall using the Thiessen Polygon method is calculated using the help of QGIS software to find the area of rain catchment and using the Ms Access software to calculate the amount of rain in the area.
Analysis of regional rainfall using the Isohyet method is calculated using the help of QGIS software to calculate the amount of regional rainfall.

Based on the results of the analysis of regional rainfall in Bantul Regency, the Thiessen Polygon method with the Isohyet method has a maximum difference of 4.44 mm and a minimum difference of 0.04 mm. The ratio of regional rainfall in Bantul Regency has a difference with a minimum coefficient value of 0.06%, a maximum of 3.69% and an average of 2.27%, so it can be concluded that the analysis of regional rainfall using the Thiessen Polygon and Isohyet methods has retalive results. the same, thus the two methods can be used for the calculation of further hydrological analysis such as planned discharge, repeat times and so on.