Rainfall event data from the Likhu Khola, in 1992 and 1993, indicate that highmagnitude
events occurred throughout the monsoon and pre-monsoon period, but
with a higher frequency in late July and early August. An analysis of measurements
for 1993 is shown in Fig. 2. The frequency distributions of rainfall magnitudes were
highly skewed, with most of the rainfall occurring in bursts of less than 5 mm.
Maximum continuous rainfall (defined as no breaks in monitored rainfall exceeding
30 minutes) during the two monitored seasons was 102.4 mm. This magnitude falling
within one day has a return period of approximately 1.7 years, using Kakani
maximum 24-hour rainfall data for 1972–86 as the baseline. However, rainfall intensity
patterns within storms were complex and highly variable. Short-duration intensities
were often high, reaching a recorded maximum of 144 mm hr–1 for maximum
1-minute intensities (Table 1) and 129.60 mm hr–1 for maximum 5-min intensities.
This meant that both rainfall magnitude and rainfall intensity had to be assessed
separately and included as potential explanatory variables in the analysis of water
runoff and soil erosion. The rainfall characteristics of both monitored years were
similar, except that there were slightly more higher-magnitude and higher-intensity
events in 1992.