Korean Journal of Soil Science and Fertilizer ISSN:0367-6315(Print) 2288-2162(Online) 한국토양비료학회 학회지

This study was carried out to develop a model for a upland drought forecasting system using soil available water contents (SAWC). The SAWC expressed as a percentage of the current available water content our of the total available water content. The total available water content is defined as the difference between field capacity and wilting point, and the current available water content is calculated by subtracting the wilting point from the current soil water content. The total available water content was calculated by dividing the soil characteristics by depth based on the soil depth of 60 cm, and the current soil water content was calculated by adding the previous available water content and the effective rainfall and then subtracting the actual evapotranspiration. The actual evapotranspiration was calculated by multiplying the reference evapotranspiration, crop coefficients and water stress coefficients. The reference evapotranspiration was computed with FAO Penman-Monteith equation. Soybean was selected as the reference crop of the drought forecasting system due to its proportion in the total upland area and industrial importance. The water stress coefficient was evaluated as a function according to the soil available water condition. The drought stage was classified with five stages based on SAWC. To prepare countermeasures against drought of crop fields in upland, the information on SAWC and upland drought stage was provided to 167 cities and counties from April to October.

The schematic diagram of the model assessing soil available water content for the forecasting system of upland drought.