Updates to the Third Edition
In June, 1996, Maryland State Highway Administration (SHA) and the Maryland Department of Environment (MDE) appointed the Maryland Hydrology Panel (the Panel) to explore the development of improved procedures that would ensure an optimal balance between preserving the environmental quality of Maryland streams and the hydraulic performance of highway drainage structures. The Panel: 1) worked closely with the staffs of the two Departments; 2) extensively reviewed Maryland policies and design approaches, as well as those of other States; and 3) conducted extensive research directed toward improving the statistical and deterministic foundations of the two Department’s hydrologic modeling procedures.
In February, 2001 the Panel issued a report entitled, Applications of Hydrologic Methods in Maryland. Adoption of the recommendations of the February 2001 report has led to significant cost and time savings in the design/review processes of the two Departments through better utilization of computer and human resources. Of even greater importance, the implementation of the recommendations has increased confidence in the design computations.
As the staffs of the two Departments gained experience and confidence with the procedures recommended by the Panel in 2001, they came forward with numerous suggestions that would lead to even better approaches. The Panel reconvened in the Fall of 2002 and, following the suggestions of the two Department’s staffs, identified sufficient improvements to justify the publication of this new report.
This document presents a set hydrologic modeling procedures that are designed to ensure an optimal balance between preserving the environmental quality of Maryland streams and the hydraulic performance and safety of highway structures. These procedures are recommended by the Maryland Hydrology Panel for use by the Maryland Department of Environment and the Maryland State Highway Administration.
The document below is the September 2010 version of the Application of Hydrologic Methods in Maryland, a report prepared by the Hydrology Panel convened by the Maryland State Highway Administration and the Maryland Department of the Environment.
The following revisions are included in the September 2010 Third Edition of the Hydrology Panel report:
- Executive Summary was updated to acknowledge that three editions of the Hydrology Panel report that were completed in February 2001, August 2006, and September 2010
- The references to the Natural Resources Conservation Service (NRCS) TR-20 model were updated to the windows version of TR-20 (WinTR-20)
- All references to the NRCS Type II storm distribution were updated to the NOAA Atlas 14 temporal distributions that are developed in GISHydro and WinTR-20
- Appendix 1: the hydrologic soils group data were updated for the Eastern and Western Coastal Plain Regions using SSURGO soils data (other regions based on STATSGO data)
- Appendix 2: the flood frequency estimates were updated in the Eastern Coastal Plain Region using annual peak flow data through 2006 and updated in the Western Coastal Plain Region using annual peak flow data through 2008 (other regions based on data through 1999)
- Appendix 3: Updated regression equations were developed for the Eastern and Western Coastal Plain Regions using SSURGO soils data
- Appendix 3: Updated regression equations were developed for rural watersheds in the combined Piedmont and Blue Ridge Regions based on a new carbonate rock map
- Appendix 3: A report describing the revised regression equations is now a part of Appendix 3
- Appendix 5: Appendix 5 was deleted and a new calibration example will be added soon
- Appendix 7: The rainfall depth frequency maps were deleted
- Appendix 9: Links to the websites were updated