Evaluation of drying characteristics for revegetation around Japan using antecedent precipitation indices with daily precipitation.

Abstract

To evaluate the effects on drying characteristics for plants, API (antecedent precipitation index) was calculated for around 132 years at 63 observation sites with daily precipitation. The consecutive summer (averaged daily temperature >= 15 ℃）low API (cslAPI) days which were under the threshold with 10 mm were calculated and then yearly maximum values were determined. The days with 5% probability of occurrence were calculated with a rating curve. The drying trends of long term were evaluated using rating curves with values divided into two periods. Top 15 sites with over 5% probability of occurrence days involved those in Setouchi region and island regions, top 15 sites those with drying trends involved those in Hokkaido, Shikoku and Kyushu regions. So in these area, the drought consideration would be necessary at the future revegetation operations.