Software Update No. 1 Release Date August, 1999 SDI Environmental Services, Inc. (SDI) presently maintains the following three software applications for hydrologic modeling.
ISGW	An integrated surface and groundwater model comprised of the surface water model HSPF and the groundwater model MODFLOW. This is a FORTRAN application running in DOS.
MODPORT™	A graphical-based pre-processor for the groundwater flow model MODFLOW. MODPORT™ is also a pre- and post-processor for SDI's integrated hydrologic model ISGW. This is a Visual Basic application running in Windows 95/98.
HSPFPORT	A text-based pre-processor for the HSPF surface water component of ISGW. Inputs data for the major hydrologic functions of HSPF as used in ISGW. This is a Visual Basic application running in Windows 95/98.

Versions 2.1 of all three software packages were released in September, 1998. SDI has recently started documenting the improvements made to ISGW and its two pre- and post-processors, HSPFPORT and MODPORT™. This work will culminate in new versions planned for release in the fall of 1999. ISGW Version 2.5 will continue to offer the hydrologic modeling community a powerful new tool for evaluating water resource projects where the interaction between the surface water system and the groundwater system plays an important role.

ISGW Improvements

On-going model development activities by SDI have resulted in several improvements to ISGW. Additional improvements were recommended by a joint ISGW Technical Advisory Committee, which was comprised of staff from the Southwest Florida Water Management District, the University of South Florida, Tampa Bay Water (a large regional water utility applying the model) and SDI.

Groundwater Above Land Surface

Groundwater that rises above land surface in the groundwater component of ISGW had previously been directed to surface water lateral inflow. It was agreed that groundwater would be allowed to stay on the land surface. Code changes were made to allow this and other options.

Seasonal Surface Water Parameters

An existing capability of HSPF was incorporated within ISGW to improve seasonal (monthly) patterns of surface water runoff and evapotranspiration.

Improved Definition of Storage Terms Affecting Runoff

Runoff in HSPF is controlled by numerous parameters, including soil water storage terms. Observed variances in simulated low-flow conditions under increased groundwater stress were effectively eliminated by defining control volumes based on original and recently modified HSPF concepts.

MODPORT™ Improvements

Expanded ISGW Post-Processing Options

New routines were added to display areal groundwater recharge and discharge patterns.

Display of Larger Map Files

Memory allocation increased to allow display of larger DXF and BLN files for map overlays.

Improved Grid Modification Options

Features dividing and combining MODFLOW grid rows and columns containing input data values were improved.

HSPFPORT Improvements

Input of Seasonal Surface Water Parameters

The user can input and select one of four user-defined patterns of monthly values for applicable HSPF parameters.

Additional Information

This update summarizes recent improvements to the software developed by SDI. Additional information on selected topics is available or specific questions can be addressed by contacting SDI.