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Comparison of simulated water, nitrate, and bromide transport using a Hooghoudt‐based and a dynamic drainage model
Author(s) -
Mollerup Mikkel,
Abrahamsen Per,
Petersen Carsten T.,
Hansen Søren
Publication year - 2014
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2012wr013318
Subject(s) - nitrate , drainage , environmental science , bromide , hydrology (agriculture) , geology , geotechnical engineering , chemistry , ecology , biology , organic chemistry
For large‐scale hydrological modeling, the accuracy of the models used is a trade‐off with the computational requirements. The models that perform well on the daily/meter scale may not perform well when applied at the yearly/kilometer scale. We compare two models of water flow and nitrate and bromide transport in a tile drained soil. The first model is based on a 2‐D grid with an explicit drain node, here called the Dynamic Drainage Model (DDM). The second and less computationally expensive model is based on an 1‐D vertical discretization where the horizontal flow is included as a sink term based on the Hooghoudt theory, here called the Hooghoudt Drainage Model (HDM). Both are based on Finite Volume Method solutions to Richard's equation and to the advection‐dispersion equation (ADE), and embedded within the Daisy agroecological model, which includes the nitrogen cycle. The two models are run with 10 years of weather data and three different lower‐boundary conditions. Losses of water, nitrogen, and bromide to both drain pipes and deep percolation/leaching are compared between the models, at daily and yearly time scales. In no case do we find the discrepancy large enough to warrant a rejection of the use of the faster HDM instead of DDM. For the daily time scale, we find in general a higher Nash‐Sutcliffe efficiency coefficient for water (0.98–1.00) than for nitrate (0.97–1.00), and the lowest for bromide (0.95–1.00). The results are explained with a low concentration gradient along the water flow pathway toward the drain.