A comparison of statistical methods for benchmarking the threshold of daily precipitation extremes in the Shanghai metropolitan area during 1981-2010

The Shanghai metropolitan area is physically and socio-economically vulnerable to extreme precipitation events and associated flooding due to its location on the Yangtze estuary, low topography and high density of human activity. This paper presents a statistical analysis for the threshold of daily precipitation extremes at the city scale using percentile indices, probability distribution and detrended fluctuation analysis (DFA). A comparison of the statistical results with consideration of local impact factors suggests that the threshold of daily precipitation extremes over Shanghai increases from 70 mm in the western region to 80 mm in the city centre and then decreases to 75 mm in coastal areas. Finally, further suggestions are presented for decision makers, researchers and other concerned stakeholders to give a more complete picture of urban climatic extremes.