Hydorlogic 2

USGS has developed a Modflow Model of the flow represented in Figure 7. A sequence of figures and tables are presented to provide engineering and resource development data; aquifer depths and thicknesses of aquifer components are listed in Table 4, hydraulic conductivities of aquifer layers are presented in Figure 8, Hydraulic properties are also provided in Table 5 with clear sourcing of data, an example of recent Modflow output of water balance flows for the aquifer system as well some of the assumed values are presented in Figure 9. The author thinks that the existence of the Modflow Model is important and would argue that this tool can lead to greater understanding of aquifer phenomenon and the analysis of future water demand or effects of climate change related availability. This is a good rationale for presenting information about the model. However, the modelling effort and content is impenetrable to the casual reader (5 USGS reports), and therefore a simplified discussion of the St. Francois and Salem Plateau Aquifer will follow these figures The reader is reminded that USGS is now publishing data based on the output of Modflow models and any use of these data should be based on an understanding of model details. In the present case, the newer models are being used to model sub regional water budgets in state water plans. . The Author has not investigated model calibration and validation and this is an important factor to be considered by the reader.