County Precipitation Estimates, March 2009

Report produced by the The Department of Agriculture and Land Stewardship, Climatology Bureau.

County Precipitation Estimates, April 2009

Report produced by the The Department of Agriculture and Land Stewardship, Climatology Bureau.

County Precipitation Estimates, May 2009

Report produced by the The Department of Agriculture and Land Stewardship, Climatology Bureau.

County Precipitation Estimates, June 2009

Report produced by the The Department of Agriculture and Land Stewardship, Climatology Bureau.

County Precipitation Estimates, July 2009

Report produced by the The Department of Agriculture and Land Stewardship, Climatology Bureau.

Development of an Expert System for Forecasting Frost on Bridges and Roadways in Iowa, HR-305, 1991

An expert system has been developed that provides 24 hour forecasts of roadway and bridge frost for locations in Iowa. The system is based on analysis of frost observations taken by highway maintenance personnel, analysis of conditions leading to frost as obtained from meteorologists with experience in forecasting bridge and roadway frost, and from fundamental physical principles of frost processes. The expert system requires the forecaster to enter information on recent maximum and minimum temperatures and forecasts of maximum and minimum air temperatures, dew point temperatures, precipitation, cloudiness, and wind speed. The system has been used operationally for the last two frost seasons by Freese-Notis Associates, who have been under contract with the Iowa DOT to supply frost forecasts. The operational meteorologists give the system their strong endorsement. They always consult the system before making a frost forecast unless conditions clearly indicate frost is not likely. In operational use, the system is run several times with different input values to test the sensitivity of frost formation on a particular day to various meteorological parameters. The users comment. that the system helps them to consider all the factors relevant to frost formation and is regarded as an office companion for making frost forecasts.

Potential-Scour Assessments and Estimates of Maximum Scour at Selected Bridges in Iowa, HR-344, 1995

This report presents the results of potential-scour assessments at 130 bridges and estimates of maximum scour at 10 bridges, in Iowa. All of the bridges evaluated in the study are constructed bridges (not culverts) that are sites of active or discontinued streamflow-gaging stations and peak-stage measurement sites. The period of the study was from October 1991 to September 1994. The potential-scour assessments were made using a potential-scour index developed by the U.S. Geological Survey for a study in Tennessee. Higher values of the index suggest a greater likelihood of scour-related problems occurring at a bridge. The estimates of maximum scour were made using scour equations recommended by the Federal Highway Administration. In this study, the long term aggradation or degradation that occurred during the period of streamflow data collection at each site was evaluated. Although the abutment-scour equation predicted deep scour holes at many of the sites, the only significant abutment scour that was measured was erosion of the embankment at the left abutment at one bridge after a flood.