Presenter
Prof. Lili Yu, General Institute of Water Resources and Hydropower Planning and Design
Co-author(s)
Dr. Yan Yang, General Institute of Water Resources and Hydropower Planning and Design
Sub-theme
1. Water-Human-Economy(Agriculture, Industry, City...)-Ecology Nexus under a Changing Environment
Topic
1-3. Balanced and coordinated development of water-economy-ecology system
Body
The third-round nationwide groundwater resources assessment in China has just been completed, in which the amount of renewable groundwater resources and “sustainable yield”has been calculated for each county. This assessment proposed an innovative study of the meaning and calculation methods of “sustainable yield”of groundwater. The “sustainable yield” refers to the amount of water that humans can extract from underground aquifers for economic and social development under the premise of maintaining sustainable groundwater use and healthy ecosystems. In this study, the concept of "reasonable groundwater level" is introduced into the calculation. At this level, groundwater can have enough discharge to rivers and lakes and evaporation to maintain the demand for groundwater from natural environment. When calculating the “sustainable yield”, the natural discharge including groundwater discharged to rivers and lakes, evaporation corresponding to a reasonable water level should be calculated first, and then deduct this natural discharge from the total groundwater recharge. In specific assessment, groundwater recharge and discharge in current situation have been computed and are the known data for “sustainable yield” calculation. However, some areas currently are in a situation of groundwater over-exploitation, that is, the current water level is lower than the "reasonable level", and the current natural discharge is less than the amount that should be maintained, which requires some further analysis and calculation. The assessment results show that the amount of “sustainable yield” in the national plain area accounts for about 70% of the amount of renewable groundwater resources, which varies greatly from region to region. For the northwest arid region, this proportion is only about 40%.Based on the calculation of the “sustainable yield”, considering current regional groundwater development and utilization, as well as the future water resources allocation plan, the “Dual Control Indexes” for groundwater extraction and groundwater level for each county are developing. The effectiveness of a region's groundwater management and protection efforts can be evaluated based on the “Dual Control Indexes”.