Exploring the role of hydrological pathways in modulating multi-annual climate teleconnection periodicities from UK rainfall to streamflow

Abstract

Abstract. An understanding of multi-annual behaviour in streamflow allows for better estimation of the risks associated with hydrological extremes. This can enable improved preparedness for streamflow-dependant services, such as freshwater ecology, drinking water supply and agriculture. Recently, efforts have focused on detecting relationships between long-term hydrological behaviour and oscillatory climate systems (such as the North Atlantic Oscillation – NAO). For instance, the approximate 7 year periodicity of the NAO has been detected in groundwater-level records in the North Atlantic region, providing potential improvements to the preparedness for future water resource extremes due to their repetitive, periodic nature. However, the extent to which these 7-year, NAO-like signals are propagated to streamflow, and the catchment processes that modulate this propagation, are currently unknown. Here, we show statistically significant evidence that these 7-year periodicities are present in streamflow (and associated catchment rainfall), by applying multi-resolution analysis to a large data set of streamflow and associated catchment rainfall across the UK. Our results provide new evidence for spatial patterns of NAO periodicities in UK rainfall, with areas of greatest NAO signal found in southwest England, south Wales, Northern Ireland and central Scotland, and show that NAO-like periodicities account for a greater proportion of streamflow variability in these areas. Furthermore, we find that catchments with greater subsurface pathway contribution, as characterised by the baseflow index (BFI), generally show increased NAO-like signal strength and that subsurface response times (as characterised by groundwater response time – GRT), of between 4 and 8 years, show a greater signal presence. Our results provide a foundation of understanding for the screening and use of streamflow teleconnections for improving the practice and policy of long-term streamflow resource management.

The importance of non-stationary multiannual periodicities in the North Atlantic Oscillation index for forecasting water resource drought

“…The same 7.5-year periodicity is also the strongest average mode of periodic behaviour in water resource drought. Periodicities of similar lengths have previously been detected in European GWL records, such as those in the UK (Rust et al, 2018;Holman et al, 2011), Hungary (Garamhegyi et al, 2018), Spain (Luque-Espinar et al, 2008), Italy (De Vita et al, 2012 and Germany (Liesch and Wunsch, 2019), as well as European streamflow records, for example in the UK (Rust et al, 2021a;Burt and Howden, 2013) and Sweden (Uvo et al, 2021). Our results therefore are consistent with principal periodicities detected in wider European water resources and highlight the NAO's wide-scale control on water resource drought.…”

“…The continuous-wavelet transform (CWT) was performed on the drought coverage time series for groundwater and streamflow to understand the frequency behaviour of widespread water resource drought over time. The CWT is often used in geoscience to understand non-stationarities of a variable over time and frequency space (Sang, 2013).…”

“…A growing number of studies have identified stronger relationships between the NAOI and certain water resource variables at multiannual periodicities (Holman et al, 2011;Neves et al, 2019;Uvo et al, 2021) than at an annual scale. This is particularly apparent where longer hydrological response times predominate (Rust et al, 2021a). For instance, Neves et al ( 2019) identified significant relationships between the NAOI and groundwater level in Portuguese aquifers and at approximately 6-and 10-year periodicities, with associations to episodes of recorded groundwater drought.…”

“…Furthermore, Liesch and Wunsch (2019) found significant coherence between NAOI and groundwater level at approximately 6-to 16-year periodicities across the UK, Germany, the Netherlands and Denmark. Rust et al (2019Rust et al ( , 2021a identified a similar significant 6-to 9-year cycle across a large dataset of groundwater level (59 boreholes) and streamflow (705 gauges) in the UK, which was associated with the principal periodicity of the NAO (of a similar length; Hurrell et al, 2003;Zhang et al, 2011). In the instance of groundwater level, this periodicity was found to represent a notable portion of overall behaviour (40 % of the standard deviation), and minima in the cycle were shown to align with recorded instances of widespread groundwater drought (Rust et al, 2019).…”

Heat-related mortality prediction using low-frequency climate oscillation indices: Case studies of the cities of Montréal and Québec, Canada

“…8 These indices can then be used to predict local climate characteristics like the frequency and intensity of heatwaves. [9][10][11] In addition to heat waves, these indices also predict variations of other weather variables such as precipitations, [12][13][14] thus potentially affecting the vulnerability of populations to extreme meteorological events.…”