The researchers studied how water moves between different underground layers in the Aksu River Basin to understand the recharge and discharge of groundwater. They found that the confined aquifer gets most of its water from the unconfined aquifer, mainly through side and leakage recharging. However, the downstream area receives very little recharge from the unconfined aquifer and is mainly drained by lateral flow and artificial pumping. This imbalance causes the downstream aquifer to have less water coming in than going out, leading to a negative balance state.