Uncertainty and Climate Variability in the Design and Operation of Water Resources Projects : Examples and Case Studies

There are two common problems in flood
hydrology: 1) estimate the return period for a given flood;
and 2) estimate the flood for a given return period. A
commonly used procedure to solve these problems is to fit a
probability density function such as the Gumbel, Pearson
type three or the generalized extreme value distributions to
the historical data. The Pearson probability distribution
was named after the statistician Pearson, it is also called
the three-parameter gamma distribution. The Mann-Kendall
test is a non-parametric test for identifying trends in time
series data. The test compares the relative magnitudes of
sample data rather than the data values them. One benefit of
this test is that the data need not conform to any
particular distribution. The data values are evaluated as an
ordered time series. Each data value is compared to all
subsequent data values. There are basically two approaches
to downscale coupled climate model projections: statistical
and dynamic downscaling.