WORLD METEOROLOGICAL ORGANIZATION 
HOMS COMPONENT 

Explanation of the criteria for classification and numbering of components  L20.3.12 (JAN 98) 

Explanation of the dates on the component's description  
SGMP: SIMULATION OF WATERTABLE BEHAVIOR IN GROUNDWATER SYSTEMS 

1. Purpose and objectives The program SGMP simulates the dynamic behavior of groundwater systems. After calibration and validation using historical data, the model can be used to evaluate the impacts of various water management scenario's on future watertable behavior. The program can also be used to assess 2. Description The model is based on the two wellknown equations: Darcy's law and the equation of conservation of mass. The combination of these two equations results in a partial differential equation for unsteady flow. The solution of a partial differential equation is obtained by finite difference method. This method requires that space be divided into small but finite intervals resulting in an equivalent system of difference
differential equations, the simultaneous solution of which gives the function of h at a finite number of nodes. Since the watertables at the nodes change with time owing to changes in recharge and abstraction, the model also requires a discretization of time. Hence a number of successive 3. Input The program is fully interactive and userfriendly with popup menus and help screens to guide the user through the data entry. Basic input data are the type, extent and geometry of the aquifer system under consideration, and the aquifer characteristics like thickness,
transmissivity and storativity. The calculations can be made in two modes. In both modes, initial watertable elevations must be prescribed together with timedependent boundary conditions like heads or fluxes. In normal mode, timedependent nodal net recharge also need to be prescribed, whereas in the inverse mode timedependent nodal watertable elevations are required for all nodes in the nodal network. 4. Output The results of the simulations are basically nodal watertable elevations as function of space and time; from these data, nodal groundwater balances are derived. The results of the calculations can be 5. Operational requirements and restrictions Minimum requirements are a personal computer with 80286 micro processor, 640 kB RAM, 20 MB hard disc, EGA graphics, MSDOS operating system; coprocessor is recommended. The program is based on the following assumptions and restrictions: 6. Form of presentation The program is available on diskette. A separate publication, ILRI Publication 29, is available on the principles of the model, including guidelines how the required input data can be processed from available field data. 7. Operational experience The program has been used in various groundwater studies in Egypt, Pakistan, and India. More than 1000 copies have been distributed all over the world. The program has also been used successfully both in national and international training courses on groundwater management. 8. Originator and technical support International Institute for Land Reclamation and Improvement ILRI 9. Availability Through the HOMS National Reference Centre for The Netherlands, or directly from ILRI. 10. Conditions on use The program and manual are separately for sale. Discounts are available for educational purposes.


(First entered: 31 JULY 01  Last updated: 19 JAN 98) 