Equipped with complex terrain structure, physical models provide an alternative way in understanding and modeling how critical zone shapes hydrologic processes in headwaters for hydrology research and education. However, this type of physical models is limited by frustrating rain-erosion or gully-erosion. Herein, the technique of permeable bricks with cementation property that can help to solve the soil backfilling problem was adopted to construct a physical model with complex terrain. Through material tests for different aggregate-cement ratios, we found that saturated hydraulic conductivity (Ksat) of samples is well correlated with bulk density (BD), e.g., the correlation coefficient (R 2) is as high as 0.75 between Ksat and BD. Then, the test material selected was applied as a soil alternative in the physical model in which two artificial soil layers have been designed through altering BD. Additionally, the non-uniform scaling of terrain was applied for the convenience of teaching, and it was constructed by reducing a steep 0.31-ha zero-order basin to 1/130 in horizontal direction and 1/30 in vertical direction. Multiple observation items, e.g., shallow groundwater level, soil moisture content, subsurface and surface runoff, etc., could provide potential opportunity to explore the role of soil and terrain in modulating streamflow. We'd like to share this effective tool to facilitate the research works of critical zone science and enrich experimental teaching methods.

<p>Equipped with complex terrain structure, physical models provide an alternative way in understanding and modeling how critical zone shapes hydrologic processes in headwaters for research and education in hydrology. However, this type of physical models is limited by frustrating rain-erosion or gully-erosion. Herein, in order to replace the real-world backfilling soil, we drew on the experience of normal concrete workmanship and adjusted the raw material’s proportion for three times. And it is found that saturated hydraulic conductivity (SHC) and field moisture capacity (FMC) are both well correlated with bulk density (BD) for the developed materials in three cases. Thereby, based on the strongest correlation (R<sup>2</sup>=0.75) between SHC and BD, two-layer alternative soil has been designed through altering BD in the physical model with complex terrain. The SHC values of alternative soil are close to that of the natural soil while the FMC values are far lower. Additionally, the non-uniform scaling of bedrock terrain was applied for the convenience of teaching and construction by zooming out a steep 0.31-ha zero-order basin 130 times horizontally and 30 times vertically. And multiple observation items, including free water level, temperature and humidity of soil, as well as outflow could provide potential opportunity to explore the role of single or combined critical zone’s element in modulating streamflow. We’d like to share this effective tool to facilitate the development of critical zone science and enrich experimental teaching methods.</p>