Overview
In June, 1996, Maryland Department of Transportation State Highway Administration (MDOT 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.
The Hydrology Panel has continued to meet continuously since publication of the first edition of the report. A second edition was published in 2006, a third edition in 2010, a fourth edition in 2016, a fifth edition in 2020, and now the sixth edition in 2023. This web page provides an archive of all editions of the report.
This document presents a set of 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 Panel for use by MDE and MDOT SHA.
Download Report
The documents below represent a comprehensive archive of all editions of the report: Application of Hydrologic Methods in Maryland, prepared by the Hydrology Panel convened by the Maryland Department of Transportation State Highway Administration and the Maryland Department of the Environment.
Updates in the Sixth Edition
The Sixth Edition of the Maryland Hydrology Panel Report recommends the use of future precipitation from Global Climate Models for certain types of MDOT-SHA projects. The recommendation is to use the median ratio for the high emission scenario RCP 8.5 for the time period 2050-2100, available from the Mid-Atlantic Regional Integrated Sciences and Assessments (MARISA) web site for the Chesapeake Bay watershed. Future precipitation is recommended for the final design discharges for the following types of projects in Maryland:
- FEMA hurricane evacuation routes
- Areas with vulnerable assets that are susceptible to sea level rise, riverine flooding, scour or other disruptive flooding events, and
- Areas with limited adaptive capacity that include roadways that are the only means of emergency vehicle access and would result in significant detour length if closed due to flooding.
The other major revision in the Sixth Edition of the Hydrology Panel Report is the addition of new regression equations for the Eastern and Western Coastal Plain Regions. The new regression equations are based on percent A soil from the SSURGO soils data dated October 2021. The new soils data are based on the Dominant Condition approach for aggregating the soils data. In the July 2020 Fifth Edition of the Hydrology Panel Report, the regression equations were based on the SSURGO data dated May 2018, which used the Dominant Component approach for aggregating the soils data. The only change in the regression equations is the percent A soils, as the flood frequency data are still based on annual peak flow data through the 2017 water year.
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