Characteristics of the aquifer structure and groundwater conversion model in the northeastern Yunying Basin

Water resources are rare in the northeast part of the Yunying Basin in northern Hubei. Groundwater in the Paleogene-Quaternary aquifers is the main source of water for production and domestic use. It is urgent to examine the aquifer structure and the relation of groundwater conversion between the aquifers, and provide the hydrogeological basis for the rational development and utilization of groundwater in this area. Through hydrogeological survey and drilling, the study area is divided into two sub-regions (six subregions), and the dynamic characteristics of groundwater levels of different aquifers are obtained by long-term monitoring of groundwater level dynamics. A model describing the relationship between aquifer recharge, runoff and excretion is established. The groundwater receives recharge from rainfall and lateral runoff recharge of weathered fissure groundwater in the metamorphic rocks, and mainly discharges in the form of horizontal runoff through the Paleogene pore-fissure aquifer and Quaternary pore confined aquifer, and then flows into the unconsolidated unconfined aquifer. Groundwater and surface water supplement and excrete each other in different seasons. The pore-fissure groundwater is closely related to the pore groundwater, which is recharged to each other and forms a vertical multi-layer water-bearing system with unified hydraulic connection. The unique aquifer structure determines the conditions for groundwater receiving poor recharge in the region, and the groundwater resources are generally poor. It is recommended to focus on the use of regional surface water resources, moderately develop groundwater resources, promote agricultural water-saving irrigation projects, and realize sustainable use of water resources.