Regional approach to estimating groundwater resources.

The feasibility of making regional estimates of groundwater resources have been demonstrated in Minnesota. Data from three research approaches were used to estimate groundwater resources: (1) groundwater contribution to the streamflow; (2) 30-day low flow characteristics of Minnesota streams; (3) groundwater hydrographs. Comparison of results of the three methods shows that values derived from groundwater hydrographs and data on groundwater contribution to streams are relatively close. Values derived from low-flow data, however, were consistently smaller. This discrepancy is related to two factors: (1) the limited time for which records of low-flow measurement were available; (2) the severely limited accuracy of low-flow estimates. However, the use of all three methods in conjunction does provide meaningful estimates of groundwater resources.