Presenter: Dr. CHEN YING, water resources managment center,Ministry of water resources
Co-author(s): Prof. CHEN MIN JIAN, individual
Sub-theme
6. Innovation for Water Governance and Management
Topic
6-3. Adaptive water management
Body
Groundwater is an alternative source to surface water in most places available from a well.The role of groundwater is often adopted as providing a vast resource being increasingly tapped for people’s vital uses,e.g.irrigation, domestic uses,and industry. However,The role of its ecological services is not recognized clearly until it becomes ever scarce.The ignored services of groundwater are invisible and hard to quantify with which often maintains the stream flow,the wetland,the vegetation, especially when it is not raining, and maybe the only water source for many people, animals, and organisms in various locations. The depletion of groundwater is caused primarily by mismanagement,e.g.,overpumping,but also by reduced natural recharge due to climate change and urbanization. Managing groundwater is as much about managing water and land users as about managing aquifer resources. This paper aims at making full use of metering data from water aquifer as visible tool on the complex context of hydro-ecological relationship to simplify groundwater cycle, the balance between utilization and recharge.We developed quantitative relationships between the groundwater depth and vegetation,plant species and the process of development, to propose groundwater withdrawal thresholds. The paper provides case study with three geomorphic types of alluvial fan plain, and loess tableland in Shannxi province in China. Differential experiments were observed in irrigation zone and urban zone.A maximum depth groundwater depth in terrace area in Xi’an city is 7.62m and minim 1.67m. The maximum groundwater depth in loess tableland area in Xi’an city is 47.23m. Defining hydro-ecological relationships as thresholds can support management decisions.Its “min depth metric” and “max depth metric” values were the highest of the minimum values (most shallow) and lowest of the maximum (deepest) values for the vegetation, respectively. The result is a mean water table depth and range for species that reflects the full range of “micro-hydrologies” where it grows in these sites. The min depth metric in the case study area is set to avoid soil salinization.The maximum depth in alluvial fan is to ensure the continuous flow of the river. This method takes a precautionary approach by setting the threshold higher than the maximum groundwater depth. The results of the research has been put into practice by local water managers and people who need to draw groundwater. This paper put forward a theoretical analysis of the challenging groundwater issues and present a management tool considering ecological conservation demand.