Articles | Volume 21, issue 3
Research article
10 Mar 2017
Research article |  | 10 Mar 2017

Vegetation dynamics and climate seasonality jointly control the interannual catchment water balance in the Loess Plateau under the Budyko framework

Tingting Ning, Zhi Li, and Wenzhao Liu

Abstract. Within the Budyko framework, the controlling parameter (ω in the Fu equation) is widely considered to represent landscape conditions in terms of vegetation coverage (M); however, some qualitative studies have concluded that climate seasonality (S) should be incorporated in ω. Here, we discuss the relationship between ω, M, and S, and further develop an empirical equation so that the contributions from M to actual annual evapotranspiration (ET) can be determined more accurately. Taking 13 catchments in the Loess Plateau as examples, ω was found to be well correlated with M and S. The developed empirical formula for ω calculations at the annual scale performed well for estimating ET by the cross-validation approach. By combining the Budyko framework with the semi-empirical formula, the contributions of changes in ω to ET variations were further decomposed as those of M and S. Results showed that the contributions of S to ET changes ranged from 0.1 to 74.8 % (absolute values). Therefore, the impacts of climate seasonality on ET cannot be ignored, otherwise the contribution of M to ET changes will be estimated with a large error. The developed empirical formula between ω, M, and S provides an effective method to separate the contributions of M and S to ET changes.

Short summary
The relationship between controlling parameters of annual catchment water balance and climate seasonality (S) and vegetation coverage (M) was discussed under the Budyko framework and an empirical equation was further developed so that the contributions from M to actual evapotranspiration (ET) could be determined more accurately. The results showed that the effects of landscape condition changes to ET variation will be estimated with a large error if the impacts of S are ignored.