제주도 어승생 수원지 주변 관정의 지하수위 변동 특성

Abstract

In this study, the hydraulic characteristics and groundwater variation characteristics due to precipitation and pumping for the wells (observation well (OW), pumping wells (PW1 and PW2)) located in Eoseungsaeng, Jeju Island, were investigated. The results of this study are summarized as follows: From the geologic columnar section of study wells, it was difficult to find the similarity of aquifers even though the distance among the wells was only in the range from 127.7 to 233.2 m, together with different geologic characteristics. Comparing groundwater level drawdown between single pumping (OW) and simultaneous pumping (OW, PW1, PW2), it was 2 to 19 times greater for the latter, indicating the groundwater level variation characteristics due to the pumping of groundwater, i.e., it means that the effect of the pumping in the downstream areas appears, even if individual hydraulic characteristics are shown between the wells. Cross Correlation analysis of precipitation and groundwater levels showed a low correlation of –0.4 to 0.3 m in all observation periods, with a lag time of 258 to 279 days when its correlation was the highest. In case of single groundwater pumping at OW, the groundwater level dropped by 0.0626 m/day, and in case of simultaneously pumped OW, PW1, and PW2, it dropped by 0.1303 to 1.212 m/day. According to the analysis of the correlation between the cumulated amount of pumping and the groundwater level, the transmissivity was in the range of 0.88～0.99 ㎡/day, and the effect of the ground water drawdown was significant due to the groundwater pumping. As a result of analyzing the ability to recover the ground water level in natural conditions without groundwater pumping, it increased by 0.02 to 0.03 m/day. It was analyzed that the recovery period according to the case of pumping 1 day takes 4.6 to 60.6 days. According to the results of the survey on the transmissivity of each well in the study area, OW 37.73 ㎡/day, PW1 9.33 ㎡/day and PW2 13.18 ㎡/day were analyzed, showing the individual hydraulic characteristic of each well. This corresponds to 0.7 to 7% of the value of the transmissivity(geometric mean) surveyed for ground water wells in the northern basin of Jeju Island, and the drawdown caused by the pumping was considered to be large and the recovery was slow because the aquifer was not developed. Considering the suitability of various analysis methods for calculating the of aquifer characteristics using the pumping test data, it was analyzed that the Moench method reflecting the storage well effect was the most appropriate. Through this study it is found that long-term precipitation data, pumping quantity, groundwater level data, and accurate geological properties are needed to investigate the variation characteristics of groundwater wells. If all these data are established, it is considered to be very helpful in predicting the groundwater level of the groundwater well. The results of this study can be applied to understanding the characteristics of groundwater level variation in wells around Eoseungsaeng.tion of volatile fatty acids was 44.9∼56.5% at the winch-curtain type facility.