Moving toward real-time groundwater flow models in heavily stressed aquifer systems

Head-specified groundwater flow models are an emerging approach to assessing near real-time conditions in an aquifer. The models have an advantage over traditional modelling approaches in that they leverage real-time, continuous data collection by simulating transient recharge and river conditions on a very fine (daily to hourly) time interval. In areas prone to groundwater flooding or extreme irrigation during drought conditions, this information is indispensable for farmers and other stakeholders. These models also provide a unique opportunity to calculate recharge and estimate pumpage. This information is particularly valuable for hydrogeologic models in areas where reporting is not required. Furthermore, the approach allows for the simulation of reductions in natural groundwater discharge at the most extreme drought conditions, which can have adverse ecological impacts to small streams in heavily irrigated areas. It also allows for the simulation of flow reversals near a stream that cycles seasonally between gaining and losing. In this talk, we will address the application of the head-specified modelling approach in two different hydrogeologic domains. First, the Imperial Valley in central Illinois is a single unconfined aquifer with very little drawdown in the summer despite large irrigation demands. Second, the Eastern Mahomet Aquifer experiences larger declines with much smaller pumpage due to the semi-confined geology of the aquifer. The head-specified model provides insight into recharge/leakage and pumpage in both cases, as well as returning rapid results for stakeholders. The model framework is particularly valuable for implementation into a participatory modelling framework of heavily monitored aquifer systems where near real-time information is valuable.