Sponge Basin Characteristics of the Original Ecosystem in Ziquejie Terraces and its Adaptive Water Supply and Demand Balance Mechanism

Based on the analysis of the observation results of rainfall and runoff and hydrogeological exploration in the Ziquejie terraces, the concept of “equal slope underground sponge reservoir” in the terraces is proposed. Compared with the ordinary linear storage and drainage process of groundwater in the basin, the “equal slope underground sponge reservoir” has a very significant characteristic of “sponge basin” which can adjust peak and relieve dry and prolong the outflow time. The calculation formula of non-linear outflow of underground water in the “sponge basin” is given. The characteristics of this “sponge basin” and its non-linear outflow principle and the coupling relationship among irrigation, water supply and drainage of ancient terraces are demonstrated. An adaptive balance model of water supply and demand in the original ecosystem of ancient terraces is established. The model is applied to simulate a long series of water supply and demand balance in the original ecosystem of the ancient terraced field, and the check results are highly consistent with the Historical Drought Resistance records of the ancient terraced field. It is proved that the principle of non-linear groundwater outflow in sponge basin and its calculation formula are correct and practical. The research results have important guiding significance for the development, utilization and protection of other ancient terraces, and also have important reference value for the development of sloping farmland.