Identification of the interactions and feedbacks among watershed water-energy balance dynamics, hydro-meteorological factors, and underlying surface characteristics

Abstract

It is important to investigate watershed water-energy balance dynamics and their interactions and feedbacks with hydro-meteorological factors and underlying surface characteristics, to enhance the understanding of the complex interrelationships among the water, energy, soil, and biosphere cycles. In this study, the single parameter Budyko equation was used. The Budyko equation represents the water-energy balance, and the parameter n represents all the characteristics in the system that affect the partition of precipitation (P) into runoff (R) and evapotranspiration (E). The dynamics of the n in watersheds were studied. The Granger causality was adopted to explore the interactions between n and various influencing factors including hydro-meteorological factors and underlying surface characteristics. Two basins located in the Loess Plateau were selected as a case study. The results indicated that (1) the n of the Jing River Basin (JRB) has a continuous increasing trend and that of the Beiluo River Basin has a continuous decreasing trend; (2) there are strong interplays between n and R, the aridity index (Ep/P), and evaporative ratio (E/P) in both watersheds; (3) soil moisture interacts with R and E/P, thereby unidirectionally influencing the n in both watersheds; and (4) the effective irrigation area interacts with n through its strong impacts on E/P and EP/P in the JRB.