Meteorology – Storm Events

Knowledge of Precipitation Amounts and Patterns Plan drainage structures –Size temporary culverts to handle storm events during period of operations –Size permanent drainage structure to handle 100 year storms

Know Precipitation Amounts and Patterns Time operations –Expose soil during dry periods if possible –Establish vegetative cover as soon as possible –Use native vegetation whenever possible

What’s Wrong?

Become familiar with precipitation patterns Sources of data –NOAA –NWS –State climatologist Usually at Land Grant University Vast amount of data available on line Ochocos Mountains of Central Oregon

National Climatic Data Center

National Weather Service National Oceanic and Atmospheric Administration's National Weather Service

Indiana State Climatologist

Variation in Precipitation Random Seasonal Proximity to water body (lake affect) Prevailing winds with moisture Topographic

Seasonal Variation

Proximity to Water Body

Prevailing Winds

Topographic Affect Rising air cools Dew point reached Water vapor condenses to form clouds Precipitation may occur

Cloud patterns induced by passage of air current over mountains Precipitation concentrated on windward side of mountain, and mountain top Tends to be rain shadow on leeward side

Fidalgo Island in rain shadow of the Olympic Mountains. Rainforests with up to 200 inches of precipitation on the west side. Rain shadow area northeast of the Peninsula with only one- half (20 inches) of the normal rainfall for the rest of the region.

Clearwater 118.5” Coupeville 21.14” Puget Sound Area, Washington

Storm Events, 1 st Qtr.

Storm Events, 2 nd Qtr.

Storm Events, 3 rd Qtr.

Storm Events, 4 th Qtr.

Monroe County Airport, April 15-16, th th

Some Basic Hydrologic Concepts Weirs are used to measure volume of water flowing past a point.

What Happens to Precipitation? Hydrologic cycle P = RO + ET + S, Where, P ≡ precipitation RO ≡ runoff ET ≡ evapotranspiration S ≡ storage

Evapotranspiration Loss of water from a given area during a specified time by evaporation from the soil surface and by transpiration from the plants. Supports plant life Reduces water yield

Runoff Provides Major Benefits RO = P – ET Moose Creek, Clearfield County, PA (WLH)

Where does runoff go to? RO = CI + SRO + SSF + BF, –where, CI ≡ channel interception SRO ≡ surface run off SSF ≡ subsurface flow BF ≡ base flow

Where does runoff go to? –CI ≡ channel interception Precipitation falling directly into channel Susquehanna River, Clearfield, PA, (WLH)

Where does runoff go to? –SRO ≡ surface runoff or overland flow Precipitation not infiltrating soil Sheet erosion of cropland resulting from surface runoff Source:

Where does runoff go to? –SSF ≡ subsurface flow, or interflow Infiltrating precipitation intercepted by hardpan or bedrock before entering groundwater pool

Where does runoff go to? –BF ≡ base flow or ground water flow Precipitation entering water table

Research results come from experimental watersheds such as:

What We’ll Look At Erosion –Impacts of Roads Harvests Water flows –Storm events –Storage Water yield –Amount –Timing Montgemory Reservoir, Clearfield, PA, WLH