지하수위 변동 해석기법과 유역수문모형을 연계한 함양시계열 추정

Abstract

Groundwater table fluctuation method interprets the fluctuation characteristics of water table in unsteady state, having drainable pore space related to form of recharge and reaction factor related to groundwater flow. SWAT(Soil and Water Assessment Tool) is a semi-distributed watershed hydrologic model which interprets the changes in water balance according to changes in land use and soil type. With this model, it is possible to predict percolation reflecting the properties of soil and land use. In this study, time series for groundwater recharge in unsteady state was predicted by combining the groundwater table fluctuation method and the SWAT. Observation points for water table were selected at the 4 watersheds (Gangjeongcheon, Oedocheon, Cheonmicheon, and Hancheon) in the Jeju Island which feature clear water table fluctuations, and on which, the combined model was tested. First, spatially distributed percolation of the selected areas was predicted using the SWAT. The parameters of the groundwater table fluctuation method were calculated using measurement data of the water table. The aspect of the daily fluctuation of recharge time series during the simulation period from 2006 to 2010 showed that the model well reflected the rainfall events and the water table fluctuations. Recharge time series was predicted solely using the calculated parameter and the measurement data of the water tables between 2011 and 2014. This implies that recharge time series can be predicted for local watersheds based on measurement data of water table once the parameter of the combined model is determined. Groundwater table fluctuation method offers the advantage of interpreting the recharge characteristics of aquifers directly from water table data, however, it holds the limit in that it is only suitable for investigating the characteristics of aquifers of local scale. We aimed to resolve this problem using SWAT by extending the characteristics of groundwater recharge time series to subbasin with similar runoff characteristics. Establishment of groundwater recharge time series based on fluctuations of water table is expected to serve as basic data for designing plans for preventing groundwater depletion or conserving groundwater in accordance with varying degrees of groundwater use at different stages of agriculture, and for establishing more stable water resources management plans considering reservoir design.