Ecological-hydrological processes in arid environment: Past, present and future

Ecohydrology, aiming to study the interactions between terrestrial ecological systems and hydrological cycles as well as their impacts on water management, has been an emerging interdisciplinary research field since the 20th century. It hosts both natural and human regulated processes that are potentially coupled in complex ways. Understanding the ecological-hydrological processes, the fundamental mechanisms and the connections between them is critical since these processes are not isolated but integrated to impact basin- scale hydrological and biogeochemical functioning of a larger river system, especially in arid environment where water resources are considered to be the source of life. Thus, research on ecological-hydrological processes in arid environment is not only a scientific focus area but also important to sustainable development. Research projects and initiatives involved in observation, measurement, modeling and data assimilation have been well-developed for those purposes over the past 20 years. This review summarizes the historical development of ecohydrology science in China and the state-of-the-art tools available in the research framework. Five grand scientific challenges are listed as prospects and exciting opportunities for the scientific community. To advance the current ecological-hydrological processes research, scientists from multidisciplinary backgrounds (such as geography, geology, geomorphology, hydrology, geochemistry and ecology), need to unite to tackle the many open problems in new dimensions.