Non-Stationary Annual Maximum Flood Frequency Analysis Using the Norming Constants Method to Consider Non-Stationarity in the Annual Daily Flow Series

Abstract

Flood frequency analysis is concerned with fitting a probability distribution to observed data to make predictions about the occurrence of floods in the future. Under conditions of climate change, or other changes to the water cycle that impact flood runoff, the flood series is likely to exhibit non-stationarity, in which case the return period of a flood event of a certain magnitude would change over time. In non-stationary flood frequency analysis, it is customary to examine only the non-stationarity of annual maximum flood data. We developed a way of considering the effect of non-stationarity in the annual daily flow series on the non-stationarity in the annual maximum flood series, which we termed the norming Water Resour Manage (2015) 29:3615-3633 constants method (NCM) of non-stationary flood frequency analysis (FFA). After developing and explaining a framework for application of the method, we tested it using data from the Wei River, China. After detecting significant non-stationarity in both the annual maximum daily flood series and the annual daily flow series, application of the method revealed superior model performance compared to modelling the annual maximum daily flood series under the assumption of stationarity, and the result was further improved if explanatory climatic variables were considered. We conclude that the NCM of non-stationary FFA has potential for widespread application due to the now generally accepted weakness of the assumption of stationarity of flood time series.

Multiple causes of nonstationarity in the Weihe annual low-flow series

“…Average annual precipitation of the whole area over the period 1954-2009 is about 540 mm and has a wide range (400-1000 mm) in various regions. Under the significant impacts of climate change and human activities in the Weihe River basin in recent decades, the hydrological regime of the river has changed over time Jiang et al, 2015a;Xiong et al, 2015). In the Weihe basin, the impacts of agricultural irrigation on runoff have been found to be significant (Jiang et al, 2015a;Lin et al, 2012).…”

A Numerical Framework for Evaluating Flood Inundation Hazard under Different Dam Operation Scenarios—A Case Study in Naugatuck River

“…These methods can broadly be classified into two groups: statistical approaches and rainfall-runoff modeling. For statistical approaches, statistical analysis or hydrological regionalization are used to analyze hydrological data within a basin, or transfer hydrological information from one or more homogenous gauged catchments to a neighboring or geographically/hydrologically similar basin [4][5][6]. However, the quality of the estimation in the basin is subject to the continuous length of flow observations of the basin or neighboring gauged basins, and potential nonstationarity of the historical flood trend.…”

Frequency analysis of nonstationary annual maximum flood series using the time‐varying two‐component mixture distributions

“…Consequently, human activities, such as urbanization, river regulation and particularly the irrigated agriculture, have great effects on the hydrological processes in the WRB (Yu et al ., ). In recent decades, both the low flow and peak flow of the WRB have exhibited significant decreasing trends (Song et al ., ; Xiong et al ., ; Yu et al ., ; Zuo et al ., ). Du et al () and Xiong et al () studied the nonstationarity of streamflow in the WRB using time‐varying single‐type distributions.…”

“…The academic debate about whether stationarity is dead focuses on the definition and interpretation of the scientific concept of stationarity and the reliability of the nonstationary models to make future predictions. In spite of these hot debates, one point has been shared that the assumption of stationarity, a conservative but reliable strategy in the practical engineering (Koutsoyiannis and Montanari, ; Lins and Cohn, ; Prosdocimi et al ., ), may be invalid in nonstationary situations (López and Francés, ; Read and Vogel, ; Salas and Obeysekera, ; Villarini et al ., ; Xiong et al ., ; Xiong et al ., ). Therefore, it is necessary to perform nonstationary frequency analysis to investigate the changes in hydrological system, with the ultimate goal to support future water resources management strategies and hydraulic engineering design (Villarini et al ., ; Read and Vogel, ; Sarhadi et al ., ).…”