engleski

Drought risk assessment along the Eastern Adriatic coast

In order to estimate the occurrence of long dry spells different return periods obtained from certain extreme value distribution are usually employed. When dealing with climatological extremes the block maxima approach is traditionally used. However, in recent years the peaks over threshold (POT) approach comes into the focus because of its ability to better utilize the available data. The main problem in this approach is how to choose the threshold in a systematic way. In this study we put emphasis on this issue while analysing dry spell series in Croatia. Daily precipitation data from the 1961-2010 period at 11 meteorological stations along the Eastern Adriatic coast are used to construct the dry spell series based on the daily precipitation of less than 1 mm. Simulated dry spell series based on Generalized Pareto (GP) distribution are employed in order to quantify the uncertainty of estimated parameters. Several methods for threshold selection are examined employing a whole range of percentile values. It is found that unique threshold cannot be recommended for dry spells. Instead, it seems the best option is to utilise GP distributions over a range of percentiles. Quantile values associated with different return periods are estimated in order to assess the drought risk along the Croatian Adriatic coast.

Dry spells; Adriatic; Threshold; Generalised Pareto distribution

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