Flinders University

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South East Regional Groundwater Flow Model- LEACHM Recharge Model

posted on 2021-11-01, 22:26 authored by Nikki Harrington, Russell Crosbie, Sebastien Lamontagne, John HutsonJohn Hutson, Leanne MorganLeanne Morgan, Adrian WernerAdrian Werner
LEACHM Recharge Model produced as a result of the GOYDER INSTITUTE FOR WATER RESEARCH Project No.E.2.6.

The LEACHM model was used to create the recharge input files for the regional groundwater flow model developed as part of the same project.

LEACHM is a one-dimensional soil water and chemical fate and transport model (Hutson, 2003). Water flow is described either by a capacity (tipping-bucket) model or by a mechanistic (Darcy-based Richard’s) model. The mechanistic model was used in this work. It was used in a previous project to assess the risk of nitrogen and pesticide contamination in the Lower South East (Fleming and Hutson, 2014).

The GIS-linked version of the LEACHM model (LEACHG) aims to assess regional behaviour. The stand-alone LEACHM input data file consists of sections describing the simulation period, profile geometry and boundary conditions, soil, vegetation, chemical properties, irrigation and chemical management and weather. In LEACHG, each of these data components vary spatially, defined by GIS rasters based on state soil and land use maps, along with spatially interpolated weather data. In addition, features such as water table depth and land surface slope class etc. may also be applied to the model in GIS format. In LEACHG, each of the data file components are selected from a library of input data files linked to raster ID values. For example, if a land use raster cell has an ID of 23, then LEACHG will read data from a library file named Crops.023. Initially, the model reads all relevant rasters, identifies unique combinations of soil, land use and weather, and performs a single simulation of each combination for the defined time period. A complete set of LEACHM output files are generated for each simulation, identified by the raster ID values that are used to name the files. Post-processing generates rasters of any desired output variable, such as drainage from the soil profile, actual evapotranspiration or irrigation applications, produces summaries of water mass balance components both in terms of water depths and volumes, and generates input data files for the groundwater model MODFLOW.

The LEACHM code is written in the FORTRAN language. The code is continually improved and adapted to the requirements of specific projects and post-processing requirements; contact Dr John Hutson (John.Hutson@flinders.edu.au). The time period of the LEACHM model simulations can be extended, however this requires modifying the input data files and obtaining or generating the required climate and land use datasets.

All datasets used in the model development are stored with the model.

Location: The model domain includes the Lower Limestone Coast Prescribed Wells Area in the Lower South East of SA (South Australia), and part of the Border Designated Area, and the encompassing groundwater flow system


Primary contact

Dr John Hutson, john.hutson@flinders.edu.au

Access Rights

Conditions apply to the use of the data. Please contact Dr John Hutson for access to the data. Permission is required before the dataset can be used.

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