High-resolution streamflow trend analysis applicable to annual decision calendars: a western United States case study

Abstract

Changes in the seasonality of streamflow in the western United States have important implications for water resources management and the wellbeing of coupled human-natural systems. An assessment of changes in the timing and magnitude of streamflow resolved at fine time scales (days to weeks and seasons) is highly relevant to adaptive management strategies that are responsive to changing hydrologic baselines. In this paper, we present a regional analysis of the changes in streamflow seasonality through a broad classification of streams and quantification of increases and decreases in flow, based on a quantile regression methodology. This analysis affords a useful research product to examine the diversity of trends across seasons for individual streams. The trend analysis methodology can identify windows of change, thus revealing vulnerabilities within decision calendars and species lifecycles, an important consideration for adaptation and mitigation efforts.

Attribution of high resolution streamflow trends in Western Austria – an approach based on climate and discharge station data

“…The negative Q trends during this time of year are possibly part of the effects of earlier snowmelt timing on streamflow. This shift causes first rising and directly afterwards dropping streamflow trends in spring and summer, which were similarly found for watersheds in western North America by other daily resolved trend analyses (Kim and Jain, 2010;Déry et al, 2009). However, to fully attribute summertime Q decreases, it would be necessary to separate the effects of shifts in snowmelt timing from the effects of lower snow accumulation (and with this, lower snowmelt volumes).…”

“…In addition, daily field significances show during which DOYs the trend patterns found were significant overall. The approach of trend detection via moving averages was similarly applied in Western US by Kim and Jain (2010) and Déry et al (2009), however, they used only 3-and 5-day moving averages and they analysed trends in streamflow. In contrast, the 30-day moving average windows reduce daily fluctuations considerably.…”

“…Compared to these indicators, a measure that is based on a harmonic filter (Renner and Bernhofer, 2011) provides more robust estimates of the timing of the hydrological cycle. Other studies analysed temporally highly resolved trends (Kim and Jain, 2010;Déry et al, 2009;Kormann et al, 2014). These trends in daily resolution have the advantage that not only a shift in snowmelt timing but also other increases or decreases of the streamflow volume are revealed (Déry et al, 2009).…”

An innovative method for trend analysis of monthly pan evaporations

“…Trends of hydrologic variables have been investigated by many researchers using different methodologies (Biswas, 2003;Kahya and Kalayci, 2004;Jonsdottir et al, 2006Jonsdottir et al, , 2008Feidas et al, 2007;Kim and Jain, 2010;Yin et al, 2010;Kliment et al, 2011;Tabari et al, 2011;Jhajharia et al, 2012;Ceribasi et al, 2013;Gebremicael et al, 2013;Trajkovic, 2013, 2014;Liu and Zhang, 2013;Kazmierczak et al, 2014). Kahya and Kalayci (2004) investigated the trends of monthly streamflows of Turkey by using Mann-Kendall, Sen's T, the Spearman's Rho and Seasonal Kendall methods.…”

Modelling streamflow trends for a watershed with limited data: case of the Litani basin, Lebanon

“…In the last two decades, the detection of hydrological trends has been the focus of numerous studies for different regions (Rimbu et al 2002, Yue et al 2003, St George 2007, Kim and Jain 2010. Meanwhile, streamflow variability in different watersheds located throughout the Mediterranean region has been evaluated by many authors.…”