An Analytical Baseflow Coefficient Curve for Depicting the Spatial Variability of Mean Annual Catchment Baseflow

Abstract

Catchment baseflow is jointly controlled by climate and landscape properties. Previous studies have recognized that spatial variability of mean annual baseflow coefficient (BFC = Qb/P, ratio of baseflow to precipitation) is primarily controlled by aridity index and storage capacity. However, an analytical solution of BFC in terms of the dominant controlling factors has not yet been established. The objective of this study was to develop an analytical BFC curve to depict spatial variability of BFC based on the “limit” concept of the Budyko framework. The BFC curve relates the baseflow coefficient to aridity index and storage capacity without resolving complex interactions between evapotranspiration and baseflow generation. The proposed BFC curve showed that, in the arid catchments, baseflow coefficient was primarily limited by available water (precipitation, P) and, in the humid catchments, was jointly controlled by both the available energy (potential evapotranspiration, Ep) and catchment retention capability (ratio of catchment storage capacity to P, i.e., Sp/P). Observed hydrological data from 950 catchments in Australia, the conterminous United States and the United Kingdom with diverse hydro‐climatic conditions (BFC = 0.001–0.650) were collected to demonstrate the capability of the developed curve. Results showed that the BFC curve captured the spatial variability of observed BFC in the 950 study catchments (R2 = 0.75, RMSE = 0.058). Mean annual baseflow estimated by the BFC curve agreed well with observed baseflow (R2 = 0.86, RMSE = 0.19 mm). The developed analytical curve provides an analytical solution for understanding how aridity index and storage capacity control mean annual catchment baseflow, and will improve predictability of baseflow at ungauged basins.

The Impact of an Open Water Balance Assumption on Understanding the Factors Controlling the Long‐Term Streamflow Components

“…Likewise, Cheng et al. (2021) and Yao et al. (2021) proposed analytical formulations of BFC as a function of $$\phi $$ considering, additionally, the catchment's storage capacity in their framework.…”

Improved Understanding of How Catchment Properties Control Hydrological Partitioning Through Machine Learning

“…The Budyko framework has been widely used to establish the relationship between evaporative ratio (i.e., E a / P ) and relative availability of water and energy (i.e., aridity index (AI), the ratio between long‐term E P and P , AI = E p / P ) (Budyko, 1974; Cheng et al., 2011). In the widely used Budyko framework proposed by Fu (1981) (i.e., Fu's equation), the controls of other secondary factors on partitioning are lumped into a landscape parameter ( ω ) that includes intra‐annual climate variability, soil, vegetation, and topography (Cheng et al., 2021; Fu, 1981; Zhang et al., 2004). Note that Fu's equation is further explained in Section 2.1.…”

Using Baseflow Ensembles for Hydrologic Hysteresis Characterization in Humid Basins of Southeastern China

“…Baseflow flows in the same direction as precipitation, with precipitation changes leading to baseflow changes (Salerno & Tartari, 2009). Numerous investigations of baseflow in numerous basins throughout the world (Cheng et al., 2021; Kelly et al., 2017; Rust et al., 2021) reveal that precipitation is still a significant factor influencing baseflow, whether in high or low energy zones. Baseflow will fluctuate seasonally due to changes in precipitation parameters such as total volume, intensity, and duration, and baseflow variations will be directly impacted by changes in the intra‐annual distribution of precipitation (Li et al., 2009).…”

“…Baseflow flows in the same direction as precipitation, with precipitation changes leading to baseflow changes (Salerno & Tartari, 2009). Numerous investigations of baseflow in numerous basins throughout the world (Cheng et al, 2021;Kelly et al, 2017;Rust et al, 2021) reveal that precipitation is still a significant factor influencing baseflow, whether in high or low energy zones. Baseflow will fluctuate seasonally Water…”