Maryland's Approach to SB 227 and Flooding Management
Maryland's Precipitation Data
Maryland
Department of
the Environment
Precipitation Data: "historical data that describes the relationship between precipitation,
intensity, duration, and return period (frequency)"
• IDF curves based on Technical Paper No. 40 (TP40), Rainfall Frequency Atlas of the
U.S., developed in 1961 by the United States Department of Agriculture, Soil
Conservation Service
• 2004 NOAA Atlas 14, Precipitation-Frequency Atlas of the United States, Volume 2
• 2025 Maryland updates to NOAA Atlas 14 with future predictions
.
• RAND Corporation future projected IDF curves for the Chesapeake Bay Watershed
based on the current NOAA Atlas 14 Volume 2 precipitation data with a range of
predictions for future climate change
https://midatlantic-idf.rcc-acis.org/
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