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Using High Hydraulic Conductivity Nodes to Simulate Seepage Lakes
Author(s) -
Anderson Mary P.,
Hunt Randall J.,
Krohelski James T.,
Chung Kuopo
Publication year - 2002
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.2002.tb02496.x
Subject(s) - hydraulic conductivity , hydraulic head , aquifer , modflow , hydrology (agriculture) , head (geology) , slug test , contrast (vision) , groundwater , geology , magnitude (astronomy) , environmental science , soil science , groundwater flow , geotechnical engineering , geomorphology , computer science , physics , artificial intelligence , astronomy , soil water
In a typical ground water flow model, lakes are represented by specified head nodes requiring that lake levels be known a priori. To remove this limitation, previous researchers assigned high hydraulic conductivity (K) values to nodes that represent a lake, under the assumption that the simulated head at the nodes in the high‐K zone accurately reflects lake level. The solution should also produce a constant water level across the lake. We developed a model of a simple hypothetical ground water/lake system to test whether solutions using high‐K lake nodes are sensitive to the value of K selected to represent the lake. Results show that the larger the contrast between the K of the aquifer and the K of the lake nodes, the smaller the error tolerance required for the solution to converge. For our test problem, a contrast of three orders of magnitude produced a head difference across the lake of 0.005 m under a regional gradient of the order of 10 −3 m/m, while a contrast of four orders of magnitude produced a head difference of 0.001 m. The high‐K method was then used to simulate lake levels in Pretty Lake, Wisconsin. Results for both the hypothetical system and the application to Pretty Lake compared favorably with results using a lake package developed for MODFLOW (Merritt and Konikow 2000). While our results demonstrate that the high‐K method accurately simulates lake levels, this method has more cumbersome postprocessing and longer run times than the same problem simulated using the lake package.