Baseflow originating primarily from groundwater is a critical streamflow component, although its accurate estimation is fraught with significant difficulties. This study estimates baseflow through existing graphical and digital filter methods, using actual streamflow data from a gauging station at the Alder Creek Watershed (ACW) and synthetic streamflow data at ten study locations within the same watershed simulated with HydroGeoSphere (HGS) (Aquanty Inc., 2018). There are four widely used graphical (Institute for Hydrology, 1980; Sloto and Crouse, 1996; Aksoy et al., 2008) and six digital filtering (Lyne and Hollick, 1979; Chapman and Maxwell, 1996; Furey and Gupta, 2001; Eckhardt, 2005; Tularam and Ilahee, 2008; Aksoy et al., 2009) baseflow separation approaches compared in this study. To determine the most optimal approach, baseflow estimates from real data are assessed based on the subjective concept of hydrologic plausibility, while baseflow estimates obtained from a HGS streamflow record with graphical and digital filtering methods are compared to those computed directly by HGS. Overall, results from this study indicate that baseflow hydrographs reveal a seasonal pattern at the ACW. During wintertime, streamflow is composed almost entirely of baseflow, whereas during summertime, baseflow only consists approximately 20% to 60% of streamflow. After comparing baseflow estimates with those computed by HGS, the most optimal approaches at the ten study locations are assessed. Results show that the best approach at six study locations is the FUKIH (Aksoy et al., 2009) approach, while at three locations, the Chapman and Maxwell (1996) approach and for one location, the Eckhardt (2005) approach performed the best. In conclusion, it is inferred that the most optimal approach within the ACW varies spatially.

主要来自地下水的基流是一个关键的水流组成部分，尽管其准确估计充满了很大的困难。本研究通过现有的图形和数字滤波器方法估计基流，使用来自 Alder Creek 流域 (ACW) 测量站的实际流量数据和使用 HydroGeoSphere (HGS) (Aquanty Inc. , 2018)。有四种广泛使用的图形（水文研究所，1980；Sloto 和 Crouse，1996；Aksoy 等，2008）和六种数字滤波（Lyne 和 Hollick，1979；Chapman 和 Maxwell，1996；Furey 和 Gupta，2001；Eckhardt , 2005; Tularam 和 Ilahee, 2008; Aksoy 等人, 2009) 在本研究中比较了基流分离方法。为了确定最佳方法，基于水文合理性的主观概念评估来自真实数据的基流估计，而将使用图形和数字过滤方法从 HGS 流量记录获得的基流估计与 HGS 直接计算的结果进行比较。总体而言，这项研究的结果表明，基流过程线揭示了 ACW 的季节性模式。在冬季，径流几乎完全由基流组成，而在夏季，基流仅占径流的大约 20% 至 60%。在将基流估计值与 HGS 计算的值进行比较后，评估了十个研究地点的最佳方法。结果表明，六个研究地点的最佳方法是 FUKIH（Aksoy 等，2009）方法，而在三个研究地点，Chapman 和 Maxwell（1996）方法和一个地点，Eckhardt (2005) 方法表现最好。总之，推断 ACW 内的最佳方法在空间上有所不同。