Groundwater Loading Effects of Agricultural Management Systems (GLEAMS)

Purpose

GLEAMS was developed to evaluate the impact of management practices on potential pesticide and nutrient leaching within, through, and below the root zone. It also estimates surface runoff and sediment losses from the field. GLEAMS was not developed as an absolute predictor of pollutant loading. It is a tool for comparative analysis of complex pesticide chemistry, soil properties, and climate. GLEAMS can be used to assess the effect of farm level management decisions on water quality.

Description

GLEAMS is a continuous simulation, field scale model, which was developed as an extension of the Chemicals, Runoff and Erosion from Agricultural Management Systems (CREAMS) model. GLEAMS assumes that a field has homogeneous land use, soils, and precipitation.

It consists of four major components: hydrology , erosion/sediment yield, pesticide transport, and nutrients. GLEAMS can provide estimates of the impact management systems, such as planting dates, cropping systems, irrigation scheduling, and tillage operations, have on the potential for chemical movement. Application rates, methods, and timing can be altered to account for these systems and to reduce the possibility of root zone leaching.

The model also accounts for varying soils and weather in determining leaching potential. GLEAMS can also be useful in long-term simulations for pesticide screening of soil/management. The model tracks movement of pesticides with percolated water, runoff, and sediment. Upward movement of pesticides and plant uptake are simulated with evaporation and transpiration. Degradation into metabolites is also simulated for compounds that have potentially toxic products.

Erosion in overland flow areas is estimated using a modified Universal Soil Loss Equation. Erosion in chemicals and deposition in temporary impoundments such as tile outlet terraces are used to determine sediment yield at the edge of the field.

Latest Version 3.0 (2000)
State of Development Released and final
Current Development Activity None. Last minor bug fix was 2007.

Development Contact

Southeast Watershed Research Laboratory (SEWRL)
South Atlantic Area
P. O. Box 946
Tifton, GA 31793

Main Developers

  • Southeast Watershed Research Laboratory (SEWRL)

Scope

Outcome Areas Environmental
Management Domains Land, Freshwater
Subdomains Contaminant Losses, Erosion/Sediment
Intended End Users
  • Researcher
  • Regional Council Scientist
Spatial Dimensions Unknown
Temporal Resolutions Days
Temporal Extents Years, Decades
Steady State or Dynamic Dynamic
Level of Integration Environmental

Input & Output Data

Key Input Data Land Use
Input Data Formats ASCI
Output Data Formats PDF

Accessibility

Open/Closed Source Open Source
Licence Type

User Information

Operating Systems MS Windows
Software Needed Unknown
User Interface Graphical desktop
Ease of Use Please Select
Use in Policy Process Plan (Policy Formulation), Review (Issue Identification)
Documentation

GLEAMS home page with Source code and documenation available, as well as links to publications. -  http://www.tifton.uga.edu/sewrl/Gleams/gleams_y2k_update.htm

Technical Considerations

Programming Language Fortran
Methods included for calibration and validation None
Analytical Techniques Input/output
Keywords leaching, nutrient, pesticide, root zone, soil erosion, sediment yield, hydrology
Links

 GLEAMS Homepage -   http://www.tifton.uga.edu/sewrl/Gleams/gleams_y2k_update.htm

Key References

GLEAMS - Publications and Abstracts

Associated Case Studies

GLEAMS - Waiarohia Catchment

This study of predicted impacts of proposed earthworks focuses upon a 201-hectare parcel of land that lies to the south of the Whenuapai airbase.

 

Other Key Case Studies

 Numerous applications worldwide but mostly in USA