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A. Magnuszewski
Fig. 14.2 Area and frequency of rainfall induced flood occurrence in Poland in the period 1946–
2001 after [3]
part of the catchment [7]. To be able to compare the catchments located at different
altitudes we should add one more variable of land elevation above the sea. For a
practical reasons it is more feasible to look for a index based only on hydrological
data.
One of the methods how to measure the dynamics of catchment response to rainfall
is the flashiness which reflects the frequency and rapidity of short term changes in
stream flow, especially during high runoff events [8]. Flashiness can be based on
mean daily flows. Calculated by dividing the path-length of flow oscillations for a
time interval (i.e. the sum of the absolute values of day-to-day changes in mean
daily flow) by total discharge during that time interval. This index can be used for
comparison of subcatchments having different physiographic properties. Calculation
of flashiness index requires a long data series of daily discharges which are difficult
to obtain in the study of large number of catchments.