Abstract
Arctic environments experience rapid climatic changes as air temperatures are rising and precipitation is increasing. Rivers are key elements in these regions since they drain vast land areas and thereby reflect various climatic signals. Zackenberg River in northeast Greenland provides a unique opportunity to study climatic influences on discharge, as the river is not connected to the Greenland ice sheet. The study aims to explain discharge patterns between 1996 and 2019 and analyse the discharge for correlations to variations in air temperature and both solid and liquid precipitation. The results reveal no trend in the annual discharge. A lengthening of the discharge period is characterised by a later freeze-up and extreme discharge peaks are observed almost yearly between 2005 and 2017. A positive correlation exists between the length of the discharge period and the Thawing Degree Days (r=0.52,p<0.01), and between the total annual discharge and the annual maximum snow depth (r=0.48,p=0.02). Thereby, snowmelt provides the main source of discharge in the first part of the runoff season. However, the influence of precipitation on discharge could not be fully identified, because of uncertainties in the data and possible delays in the hydrological system. This calls for further studies on the relationship between discharge and precipitation. The discharge patterns are also influenced by meltwater from the A.P. Olsen ice cap and an adjacent glacier-dammed lake which releases outburst floods. Hence, this mixed hydrological regime causes different relationships between the discharge and climatic trends when compared to most Arctic rivers.
Highlights
Various components of the Arctic system are characterised by rapid climate changes, which are mainly driven by increases in air temperature more than twice the global average [1]
An intensification of the hydrological cycle is observed coherent with the increase in air temperature, which is reflected by increases in humidity, precipitation and river discharge [2]
The aim of this paper is to describe the changes in discharge patterns in terms of the total discharge volume, peak discharge, timing of the river break-up and freeze-up and length of the entire discharge period of the Zackenberg River between 1996 and 2019
Summary
Various components of the Arctic system are characterised by rapid climate changes, which are mainly driven by increases in air temperature more than twice the global average [1]. An intensification of the hydrological cycle is observed coherent with the increase in air temperature, which is reflected by increases in humidity, precipitation and river discharge [2]. The relatively warm freshwater influx is influencing the thermohaline ocean circulation and affecting regional sea ice formation [4,5]. Arctic-draining rivers in Eurasia and North-America show an increase in freshwater discharge to the Arctic ocean, which is frequently accompanied by a shift towards an earlier start of the melt season [7,8]. An increase in atmospheric moisture content resulting in more precipitation is often proposed as the main cause of the increasing river discharges [9,10]. Meltwater-fed rivers outside of the Arctic region show varying discharge trends [14,15,16]
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