Hydrohill: A landmark public work created by Wei-Zu Gu that advances experimental hydrology

Hydrology has a long history, but is still considered a young science due to its lack of a solid scientific foundation as a natural science. Field experimentation is crucial when investigating hydrological processes and mechanisms, and is essential if hydrology is to have a solid, science-based foundation. Professor Wei-Zu Gu (1932–2022) was an internationally renowned scientist in the field of hydrology and is recognized as the greatest pioneer of experimental hydrology and isotope hydrology in China. He created the Hydrohill experimental catchment, which serves as both a great public facility for experimental hydrology and a valuable legacy for researchers that will enable them to conduct advanced hydrological experiments in the future. This legacy consists of innovative infrastructure that bridges the gap between natural watershed experiments and artificial physical models. The Hydrohill is an intensively instrumented experimental catchment that allows different elements of the hydrological cycle and their tracing indicators to be comprehensively measured. To provide an in-depth understanding of the Hydrohill, this paper presents a short history of the site, its experimental objectives, a site description (including location, construction and instrumentation), site conditions (such as soil, hydrological and meteorological properties), and its contributions to hydrological science. We acknowledge Professor Gu for creating the Hydrohill experimental hydrology facility and enhancing our understanding of hydrological processes and mechanisms. Finally, we hope that Chuzhou Scientific Hydrology Laboratory, along with support from Professor Gu's friends, will ensure the continued growth of the Hydrohill so that it can address unsolved problems in hydrology.