Scale Effects of Hydrostratigraphy and Recharge Zonation on Base Flow
- 18 November 2005
- journal article
- Published by Wiley in Groundwater
- Vol. 44 (3), 362-370
- https://doi.org/10.1111/j.1745-6584.2005.00136.x
Abstract
Uncertainty regarding spatial variations of model parameters often results in the simplifying assumption that parameters are spatially uniform. However, spatial variability may be important in resource assessment and model calibration. In this paper, a methodology is presented for estimating a critical basin size, above which base flows appear to be relatively less sensitive to the spatial distribution of recharge and hydraulic conductivity, and below which base flows are relatively more sensitive to this spatial variability. Application of the method is illustrated for a watershed that exhibits distinct infiltration patterns and hydrostratigraphic layering. A ground water flow model (MODFLOW) and a parameter estimation code (UCODE) were used to evaluate the influence of recharge zonation and hydrostratigraphic layering on base flow distribution. Optimization after removing spatial recharge variability from the calibrated model altered base flow simulations up to 53% in watersheds smaller than 40 km2. Merging six hydrostratigraphic units into one unit with average properties increased base flow residuals up to 83% in basins smaller than 50 km2. Base flow residuals changed 2 when recharge and hydrostratigraphy were simplified, respectively; thus, the critical basin size for the example area is ∼40 to 50 km2. Once identified for an area, a critical basin size could be used to guide the scale of future investigations. By ensuring that parameter discretization needed to capture base flow distribution is commensurate with the scope of the investigation, uncertainty caused by overextending uniform parameterization or by estimating extra parameter values is reduced.Keywords
This publication has 11 references indexed in Scilit:
- Role of the calibration process in reducing model predictive errorWater Resources Research, 2005
- Quantifying Ground Water Recharge at Multiple Scales Using PRMS and GISGroundwater, 2004
- Choosing appropriate techniques for quantifying groundwater rechargeHydrogeology Journal, 2002
- Improving a Complex Finite‐Difference Ground Water Flow Model Through the Use of an Analytic Element Screening ModelGroundwater, 1998
- STREAMFLOW TRENDS IN WISCONSIN'S DRIFTLESS AREA1Jawra Journal of the American Water Resources Association, 1996
- Hydrological impacts of changing land management practices in a moderate‐sized agricultural catchmentWater Resources Research, 1991
- A Method for Simultaneous In Situ Measurement in the Vadose Zone of Field‐Saturated Hydraulic Conductivity, Sorptivity and the Conductivity‐Pressure Head RelationshipGround Water Monitoring & Remediation, 1986
- Origin of Red Clay over Dolomite in the Loess‐Covered Wisconsin Driftless UplandsSoil Science Society of America Journal, 1983
- VALLEY ALLUVIATION IN SOUTHWESTERN WISCONSIN∗Annals of the American Association of Geographers, 1972
- Response of springflow to some climatic variables in southwestern WisconsinWater Resources Research, 1966