SPI 및 SDI 기반의 Seasonal ARIMA 모형을 활용한 가뭄예측 - 충주댐, 보령댐 유역을 대상으로 -

Short Term Drought Forecasting using Seasonal ARIMA Model Based on SPI and SDI - For Chungju Dam and Boryeong Dam Watersheds -

Abstract

In this study, the SPI (Standardized Precipitation Index) of meteorological drought and SDI (Streamflow Drought Index) of hydrological drought for 1, 3, 6, 9, and 12 months duration were estimated to analyse the characteristics of drought using rainfall and dam inflow data for Chungju dam ($6,661.8km^2$) with 31 years (1986-2016) and Boryeong dam ($163.6km^2$) watershed with 19 years (1998-2016) respectively. Using the estimated SPI and SDI, the drought forecasting was conducted using seasonal autoregressive integrated moving average (SARIMA) model for the 5 durations. For 2016 drought, the SARIMA had a good results for 3 and 6 months. For the 3 months SARIMA forecasting of SPI and SDI, the correlation coefficient of SPI3, SPI6, SPI12, SDI1, and SDI6 at Chungju Dam showed 0.960, 0.990, 0.999, 0.868, and 0.846, respectively. Also, for same duration forecasting of SPI and SDI at Boryeong Dam, the correlation coefficient of SPI3, SPI6, SDI3, SDI6, and SDI12 showed 0.999, 0.994, 0.999, 0.880, and 0.992, respectively. The SARIMA model showed the possibility to provide the future short-term SPI meteorological drought and the resulting SDI hydrological drought.

Fig. 1 Flow chart of the study

Fig. 2 SPI and SDI values from 1986 to 2016 at Chungju Dam watershed

Fig. 3 SPI and SDI values from 1998 to 2016 at Boryeong Dam watershed

Fig. 4 Comparison of SARIMA results of SPI and SDI series at Chungju dam watershed (2016)

Fig. 5 Comparison of SARIMA results of SPI and SDI series at Boryeong dam watershed (2016)

Table 1 Classification Range of Drought Condition for SPI value

Table 2 Classification Range of Drought Condition for SDI value

Table 3 Test results of Augmented Dickey-Fuller (ADF) about SPI and SDI at Chungju Dam and Boryeong Dam watershed

Table 4 Selection of optimal SARIMA model through Akaike’s Information Criterion (AIC) and SBC (Schwartz Bayesian Criterion) for Chungju Dam and Boryeong Dam watershed

Table 5 Statistical analysis results for SPI, SDI series using SARIMAat Chungju Dam and Boryeong Dam watershed

Table 6 Correlation analysis between observed and predicted values of SPI and SDI series using SARIMA model (2016, Chungju Dam)

Table 7 Correlation analysis between observed and predicted values of SPI and SDI series using SARIMA model (2016, Boryeong Dam)