reflecting transportation and transformation processes that are involved in land disposal of sewage effluent
The 4 models are: LEACHM
(Hutson and Wagenet 1992), a deterministic, process-based model that simulates water transport using Richards' equation; GLEAMS (Leonard et al.
For cases in which a more detailed simulation and/or field study are needed, research models such as RZWQM, LEACHM
, or ecosys, and research plots or farms can be used to establish refined values for NLI.
Some of these models are NLEAP, LEACHM
, CERES, EPIC, NTRM, RZWQM, and GPFARM.
A consistent trend was that LEACHM
under-predicted the soil water contents below 0.
able 1 Rate coefficients for nitrification and denitrification from LEACHM
calibrations (Sogbedji et al.
1998), were much more satisfying for both study sites than those obtained with GLEAMS and LEACHM
At the Institute for Plant Protection, University of Hohenheim, PRZM and LEACHM
simulations are being compared against lysimeter leaching data.
Models such as LEACHM
(Hutson and Wagenet 1992) and UNSATCHEM (Suarez and Simunek 1997), which must predict reaction among competing cations, rely on selectivity coefficients or a Gapon exchange constant, [beta], for the cation pairs in the system (Reiniger and Bolt 1972; Bolt et al.
1987), which is designed to assess management effects on pesticide movement and uses a tipping bucket approach for water movement; LEACHM
(Hutson and Wagenet 1995), which is a mechanistically based model and simulates water movement using the Richards' equation; and HYDRUS-2D (Simunek et al.
Soutter and Musy (1999) performed a global sensitivity analysis of LEACHM
using a Monte Carlo approach and found that pesticide fluxes were mostly dependent on the degradation rate constant, followed by organic carbon content then [K.
1984, 1985) and its modified version PELMO (Klein 1991), LEACHM
(Wagenet and Hutson 1987, 1989; Hutson and Wagenet 1992), CALF (Nicholls et al.