title: A multiscale investigation of ground water flow at Clear Lake, Iowa.
abstract: Ground water flow was investigated at Clear Lake, a 1468-ha glacial lake in north-central Iowa, as part of a comprehensive water quality study. A multiscale approach, consisting of seepage meters (and a potentiomanometer), Darcy's law, and an analytic element (AE) model, was used to estimate ground water inflow to and outflow from the lake. Estimates from the three methods disagreed. Seepage meters recorded a median-specific discharge of 0.25 mum/s, which produced a lake inflow rate between 90,750 and 138,200 m3/d, but no detectable outflow. A wave-induced Bernoulli effect probably compromised both inflow and outflow measurements. Darcy's law was applied to 11 zones around the lake, producing inflow and outflow values of 10,500 and 5000 m3/d, respectively. The AE model, GFLOW, coupled with the parameter estimation model, UCODE, simulated ground water flow in a 700-km2 region using 31 hydraulic head and base flow measurements as calibration targets. The model produced ground water inflow and outflow rates of 14,300 and 9200 m3/d, respectively. Although not a substitute for field data, the model's ability to simulate ground water flow to the lake and the region, estimate uncertainty for model parameters, and calculate a lake stage and associated lake water balance makes it a powerful tool for water quality management and an attractive alternative to the traditional methods of ground water/lake investigation.
authors.affiliation: Department of Geological and Atmospheric Services, Iowa State University, Ames, IA 50011, USA. bsimp@iastate.edu
authors.forename: William W
authors.initials: WW
authors.lastname: Simpkins
mesh_terms: D002138:Calibration; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D020342:Finite Element Analysis; D005618:Fresh Water; D055593:Geological Phenomena; D005844:Geology; D007484:Iowa; D012989:Soil Pollutants / Q000032:analysis; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis; D014881:Water Supply
chemical_list: D012989:Soil Pollutants; D014874:Water Pollutants, Chemical