Shifts in flood and low-flow regimes in New Zealand due to interdecadal climate variations

Abstract

Thirty-one of the longest available streamflow records for New Zealand were analysed to see whether shifts in flood and low-flow regime occurred in 1977/1978 corresponding to a shift in phase of the Interdecadal Pacific Oscillation. Annual peak flows, and annual minimum flows averaged over 28 days, for two periods, 1947-1977 and 1978-1999, were compared using box plots and statistical tests. The plots and the tests show that a decrease of flood size has occurred since 1978 in the Bay of Plenty region of the North Island, and that increases in flood size and low-flow magnitude have occurred in the South Island for most rivers with headwaters draining from the main divide of the Southern Alps and Southland. For much of the North Island apart from the Bay of Plenty, and the north of the South Island, no consistent pattern of shifts was identified.

Changes in the flood hazard in Germany through changing frequency and persistence of circulation patterns

“…77 McKerchar and Henderson (2003) found changes in several hydrological variables in New Zealand which were consistent with changes in the Interdecadal Pacific Oscillation. Jacobeit et al (2006) determined large-scale CP for historical flood events with the help of Reanalysis data.…”

Long‐term trend analysis for precipitation in Asian Pacific FRIEND river basins

“…Mantua et al (1997) found that the IPO affects coastal sea and continental surface air temperature, as well as streamflow in major west-coast river systems, from Alaska to California. On a smaller spatial scale, McKerchar and Henderson (2003) investigated the association between the shift in flood and low-flow regime and the shift in phase of the IPO. This kind of shift in ENSO behaviour could account for the trend identified for some of the river basins.…”

Trend detection in river flow series: 1. Annual maximum flow / Détection de tendance dans des séries de débit fluvial: 1. Débit maximum annuel

“…Most studies (with some exceptions, such as Mitosek, 1995) have only analysed a few rivers, or at most a region or a single country (e.g. McKerchar & Henderson, 2003;Burn et al, 2004;Callède et al, 2004;Lindström & Bergström, 2004;Xiong & Guo, 2004). In contrast, a global-scale assessment of trends in annual maximum streamflow is presented herein.…”