Baseflow signature behaviour of mountainous catchments around the North China Plain

Abstract

Baseflow is paramount to sustain the ecological integrity of river catchments. Identifying baseflow characteristics and influencing factors can facilitate the understanding of the water budget of catchments. In this study, a revised one parameter digital filter was used to separate baseflow from total daily streamflow in 18 mountainous catchments around the North China Plain (NCP). Nine baseflow signatures (BSs) including Baseflow Index (BFI), the five-distribution signature (with the representative percentiles Qb1Qb33Qb50Qb66Qb99, respectively), and the three-dynamics signature (seasonality ratio, SR; concavity index, CI; and slope of the baseflow duration curve, SBDC) were used to assess the baseflow hydrological behaviour (i.e., seasonality, stability, and sensitivity). Our findings showed (1) an apparent spatial pattern for most baseflow signatures (except for Qb1), but no particular temporal variation in the studied catchments, (2) that summer precipitation, evapotranspiration, soil texture, vegetation, and geomorphic factors (i.e., elevation and slope) were the main factors influencing the variation of baseflow, (3) that winter dominated baseflow was associated with the karst geological distribution, and (4) that Qb50, Qb66, Qb99 and CI were good predictors to estimate the BFI (R2 = 0.756). This study analysed the baseflow signature behaviour of mountainous catchments and provided insights into the hydrological processes related to baseflow.