RADIOACTIVE RAINOUT RELATIONS
ON DENSELY GAUGED SAMPLING NETWORKS
FLOYD A. HUFF
Illinois State Water Survey, Urbana, Illinois
ABSTRACT
Studies have been made of the relation between the rainout of radioactivity in convective storms and the three rainfall factors of volume,
intensity, and duration. Data were used from four densely gauged
sampling networks operated during the 1962 and 1963 spring and summer seasons in central Illinois. The network areas ranged from 10 to
6000 square miles and provided data on both microscale and meso-
scale relations. Analyses of spatial variability showed a trend for the
relative variability of radioactive rainout to (1) exceed the stormrainfall variability, (2) decrease with increasing rainfall volume and
storm duration, and (3) increase with increasing network size. Investigation of the point representativeness of single measurements of
radioactive rainout in a 15-storm sample indicated that an average
error of 20 to 25% is introduced when a single observation is assumed
to represent the mean rainout over areas of 10 to 12 square miles.
Correlation analyses indicated that at a given point the rainfall is not
strongly related to the radioactive rainout. However, when areal patterns of rainfall and rainout are compared and allowance is made for
displacement of high and low centers due to various meteorological
influences, a strong association is indicated between the major features of the patterns in most storms.
INTRODUCTION
During the 1962 and 1963 spring and summer seasons, several networks of rainwater samplers were operated in central Illinois in con507