Abstract
Baseflow plays a crucial role in maintaining the stability of streamflows, especially in watersheds. To reveal the evolution of baseflow in watersheds in southern China, this study investigated the variation in baseflow across the small watershed of Pengchongjian in Jiangxi Province. A digital filter method was applied to separate baseflow from local daily streamflow records for 1983–2014 using different values of filtering parameter (β) and filtering times (T). The separation results were validated by the baseflow index (BFI) method to determine the optimal parameters. When β = 0.90 and T = 2, the baseflow separation results conformed to the actual field situation in the watershed. The average monthly baseflow increased at first and then decreased, being unevenly distribution within a year, whereas average monthly BFI followed the opposite trend. On the seasonal scale, baseflow was ranked as spring > summer > winter > autumn, and the BFI as winter > spring > autumn > summer. Both the annual baseflow and BFI decreased at a rate of 2.30 mm/year and 0.0005/year, respectively. When considered on the annual scale, the BFI was lower in the wet years and higher in the dry years compared with normal years, averaging 0.22 in the watershed for the 1983–2014 period. This study obtained key optimal parameters for baseflow separation and revealed baseflow variation in the Pengchongjian watershed. These results provide a useful reference for studying the patterns of baseflow evolution in watersheds in southern China.
Highlights
Baseflow is an important component of streamflow, being the primary recharge of streamflow during the dry season; baseflow plays a crucial role in maintaining the stability of streamflow [1,2]
This study obtained key optimal parameters for baseflow separation and revealed baseflow variation in the Pengchongjian watershed. These results provide a useful reference for studying the patterns of baseflow evolution in watersheds in southern China
Baseflow is a vital part of groundwater resource assessment and watershed management [3], since variation in baseflow can serve as a reliable indicator of changes in groundwater level and quantity
Summary
Baseflow is an important component of streamflow, being the primary recharge of streamflow during the dry season; baseflow plays a crucial role in maintaining the stability of streamflow [1,2]. Particular, the the digital digital filter filter method method is is objective objective and and reproducible, reproducible, and and it it has has been been widely used to separate baseflow [26,27] Among such studies, the filtering parameter widely used to separate baseflow [26,27]. States by using a recursive digital filter and validated their results by the BFI method. A recursive digital filter and validated their results by the BFI method. Li et al [34] used the BFI method to determine the parameters of digital filtering for digital filtering for baseflow in arid and semi-arid. A digital filter method was used to separate the baseflow, with the Pengchongjian in southern China. Our study have aa great great reference value for obtaining accurate baseflow separation in watersheds, in addition to revealing reference value for obtaining accurate baseflow separation in watersheds, in addition to revealing patterns in understudied understudied southern southern China
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