Techniques for estimation of storm-runoff loads, volumes, and selected constituent concentrations in urban watersheds in the United States

Abstract

CD.--Total recoverable cadmium in storm-runoff load, in pounds, or in stormrunoff mean concentration, in micrograms per liter. COD.--Chemical oxygen demand in storm-runoff load or mean seasonal or mean annual load, in pounds, or in storm-runoff mean concentration, in milligrams per liter. CU.--Total recoverable copper in storm-runoff load or mean seasonal or mean annual load, in pounds, or in storm-runoff mean concentration, in micrograms per liter. DA.--Total contributing drainage area, in square miles. DP.--Dissolved phosphorus in storm-runoff load or mean seasonal or mean annual load,,in pounds, or in storm-runoff mean concentration, in milligrams per liter. DRN.--Duration of each storm, in minutes, for storm-runoff load and mean concentration models, and, in hours, for mean seasonal or mean annual load models. DS.--Dissolved solids in storm-runoff load or mean seasonal or mean annual load, in pounds, or in storm-runoff mean concentration, in milligrams per liter. IA.-Impervious area, as a percent of total contributing drainage area. INT.--Maximum 24-hour precipitation intensity that has a 2-year recurrence interval, in inches. LUC.--Commercial land use, as a percent of total contributing drainage area. LUI.--Industrial land use, as a percent of total contributing drainage area. LUN.--Nonurban land use, as a percent of total contributing drainage area. LUR.--Residential land use, as a percent of total contributing drainage area. MAR.--Mean annual rainfall, in inches. MJT.--Mean minimum January temperature, in degrees Fahrenheit. MNL.--Mean annual nitrogen load in precipitation, in pounds of nitrogen per acre PB.--Total recoverable lead in storm-runoff load or mean seasonal or mean annual load, in pounds, or in storm-runoff mean concentration, in micrograms per liter. PD.--Population density, in people per square mile. R2.--Coefficient of multiple determination; it measures the proportion of total variation about the mean Y explained by the regression. RUN.--Storm-runoff volume, in cubic feet. SS.--Suspended solids in storm-runoff load or mean seasonal or mean annual load, in pounds, or in storm-runoff mean concentration, in milligrams per liter. TKN.--Total ammonia plus organic nitrogen as nitrogen in storm-runoff load or mean seasonal or mean annual load, in pounds, or in storm-runoff mean concentration, in milligrams per liter. TN.--Total nitrogen in storm-runoff load or mean seasonal or mean annual load, in pounds, or in storm-runoff mean concentration, in milligrams per liter TP.--Total phosphorus in storm-runoff load or mean seasonal or mean annual load, in pounds, or in storm-runoff mean concentration, in milligrams per liter. TRN.--Total storm rainfall, in inches. ZN.--Total recoverable zinc in storm-runoff load or mean seasonal or mean annual load, in pounds, or in storm-runoff mean concentration, in micrograms per liter. I.--Region I representing areas that have mean annual rainfall less than 20 inches. II.--Region II representing areas that have mean annual rainfall of 20 to less than 40 inches. vi III.--Region III representing areas that have mean annual rainfall equal to or greater than 40 inches.