No abstract

While drainage installed in mountainous and urban areas play various roles for supplying and draining water, the standards for reduction facilities and maintenance are insufficient. In the case of small drainage, if there is an inflow of deposited debris, overflow damage occurs due to lack of water supply capacity. In this study, a reduction facility was developed to block the transport of debris in a small drainage. The equation considering installation standards was proposed by analyzing capture efficiency through hydraulic experiment. By establishing various experimental conditions, a total of 900 experiments were conducted using 90 different conditions. The reduction effect of reduction facilities was analyzed by consideration of flow conditions such as discharge and Froude Number. Multiple regression analysis was conducted to develop an equation that considers the installation standard of a small drainage. The dependent variable was capture efficiency, and the independent variables were discharge, Froude Number, and an effective cross sectional area of reduction facilities. The equation considering installation standard of small drainage is E = 1.337-5.074×Q-0.156F_r-132.710A and the significance is high. The results of this study are expected to be applied to reduction facilities suitable for target capture efficiency targeting small drainage.

This study aims to establish a drought index for disaster prediction in Gyeongsangnam-do, where the most agricultural drought damage occurred from 1965 to 2018. The drought index was analyzed for each duration (3, 6, 9, 12 months) targeting the SPI. Damage characteristics of the duration of agricultural drought were calculated. SPI for each duration of agricultural drought damage period in Gyeongsangnam-do was at least -2.0 or less, and the maximum was -1.0 or more, and weak and moderate drought were analyzed. However, due to the heavy rain effect during the rainy season, the average SPI12 was -1.06, and the impact of agricultural drought was negligible. It was analyzed that the correlation between the damage period of agricultural drought and the SPI by duration was high. However, there is not much difference in SPI for each duration to determine the occurrence of damage. In this study, the criterion for disaster prediction of agricultural drought was calculated as representative drought index by year as the minimum drought index of SPI for each duration of damage occurrence period of past agricultural drought. The Standard of drought index for disaster prediction was set to -1.64, the average of the SPI for each duration of year in which damage occurred in the past.