Research progress and prospect of soil hydrological processes in critical zone of the Loess Plateau

The Earth Critical Zone (CZ) is one of the frontiers and key fields of earth science in the 21st century. Loess accounts for about 10% of the global land area, and the Chinese Loess Plateau (CLP) is one of the typical Loess CZs. Soil hydrological processes drive a series of biogeochemical cycles at different scales in the CLP−CZ and determine the evolution direction and sustainability of the soil−vegetation−atmosphere continuum. Based on the "4M" research framework of the CZ science, we summarized the hot spots and frontiers of soil hydrological processes in the CLP−CZ, and then reviewed the research progresses of soil hydrological processes at different scales, including the observation methods and techniques, model simulation and mapping, and deep soil drying management. Based on this, focusing on the optimal utilization of soil water resources and the improvement of ecosystem service function in the CLP−CZ, the countermeasures and suggestions for the optimal management of soil hydrological processes in the CLP−CZ under the joint impact of global climate change and intense human activities were put forward, and the future trend of soil hydrological processes in the CLP−CZ was forecasted. A good understanding of this information is helpful to deepen the scientific understanding of the CLP−CZ research, promote the development of the CZs science, and provide scientific reference for the CLP natural resources optimization and mountains, rivers, forests, farmlands, lakes, and grasslands ecosystems management.