# Rainfall Standard of Disaster Prediction for Agricultural Droughs in S. Korea
## 3 Results
For the whole country, the annual average rainfall and the amount of agricultural drought damage from 1965 to 2018 were analyzed for rainfall in the past year (Figure 8). For the years with agricultural drought damage, the average annual rainfall was 1166 mm (min 846 mm-max 1621 mm). For the years without agricultural drought damage, the average annual rainfall in whole country was 1271 mm (min 882 mm-max 1860 mm). Agricultural drought damage was observed to occur at a small rainfall of about 105 mm, based on the average annual rainfall. The characteristics of rainfall were reviewed through a linear regression analysis of annual average rainfall in the whole country and rainfall in agricultural drought damage. The annual average rainfall estimation formula for whole country, calculated by using linear regression analysis, was \(R_{ucar}=-3710+2.50\)Y, and the rainfall estimation formula for agricultural drought damage was analyzed as \(R_{adr}=-2815+2.00\)Y. Here, Y is the year, \(R_{car}\) is the annual average rainfall in the whole country and \(R_{adr}\) is the agricultural drought damage rainfall. Using the linear regression equation, annual rainfall and annual average annual rainfall of agricultural drought damage were analyzed (Table 5). In the whole country, the damage of the past agricultural drought occurred when the average annual rainfall was less than 97 mm. The average rainfall with agricultural drought damage was 1154 mm (min 1115 mm-max 1221 mm) per year, whilst the average annual rainfall was 1251 mm (min 1203 mm-max 1335 mm). The rainfall with drought damage in South Korea averaged 97 mm (min 88 mm-max 114 mm) per year. Figure 8: Setting up rainfall for disaster prevention relevant to agricultural droughts by year. In this section, for disaster prevention of agricultural drought, the average rainfall and the amount of agricultural drought damage occurred were analyzed for municipality and the whole country. The damage of agricultural drought in the municipality occurred when the annual rainfall was less than 1199 mm or less than the municipality annual average rainfall of 101 mm at the time of observation. In the whole country, the damage of agricultural drought occurred when the annual rainfall was 1154 mm or less at the time of observation, or 97 mm or less than average rainfall in the whole country. The annual rainfall amount of 1154 to 1199 mm, which is the cause of damage to agricultural drought, was analyzed for the whole country and municipality, and the average annual rainfall was analyzed to be 97 to 101 mm. In this study, the standard of judgment point for disaster prevention of agricultural drought at the time of disaster management was analyzed for rainfall for municipality and the whole country. Rather than using various drought indices that are currently developed, policy makers or public servant made suggestions based on rainfall that is most accessible and convenient for judging the timing of agricultural drought. Thus, in this study, we set up the annual rainfall of \(\leq\)1200 or 100 mm below the average annual rainfall for the preceding year as the reference rainfall for disaster prevention relevant to agricultural droughts.