Seasonal hydrology and geochemistry of two small high Arctic catchments, Axel Heiberg Island, Northwest Territories

Publication Year:
1993
Usage 101
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Abstract Views 44
Repository URL:
https://scholars.wlu.ca/etd/377; https://scholars.wlu.ca/cgi/viewcontent.cgi?article=1376&context=etd
Author(s):
Boike, Julia
Tags:
Geochemistry; Hydrology
thesis / dissertation description
This study examines hydrological and geochemical processes in a continuous permafrost setting in the Canadian High Arctic on Axel Heiberg Island (79°25 ' N; 90°45 ' W) with the following objective: to identify spatial and seasonal variation in hydrology and geochemistry of the East Inflow (EIF) and West Inflow (WIF) sub basins draining into Colour Lake and relate them to processes operating in the basins. Field work in the catchment was carried out between 20 May to 16 August 1991 and 23 July to 20 August 1992. Surface flow and suprapermafrost groundwater in the active layer were monitored to assess seasonal changes in flowpaths of water. Water samples were taken from streams, suprapermafrost groundwaters and precipitation and analyzed for total dissolved solids (TDS), pH and major cations and anions. Hydrological and chemical processes are examined in three periods 1. snowmelt (1-12 June) 2. period of active layer development (12 June to 2 August) and 3. the rainstorm (2 August to 10 August). Results show that several processes are responsible for the observed spatial and temporal changes in the hydrology and chemistry of the streams. In the WIF/W, a large proportion of snowmelt water refreezes on boulders of the felsenmeer forming ground ice. Three results identify the melting of ground ice as an important stream flow generating factor in the WIF/W during the period of active layer development: 1. diurnal cycles in discharge 2. a positive significant correlation between air temperature and discharge 3. TDS are inversely correlated with discharge. The hydrological regime of the WIF/W, which shows the characteristics of a proglacial regime is therefore best described as "melting ground ice regime". In the EIF, geomorphological characteristics of the basin result in a higher proportion of water travelling through the active layer, thus the response of discharge to high air temperatures is significantly lagged for 2 days ("modified melting ground ice" regime). Chemical differences of the two streams are related to geological sources. Seasonal changes of ions in the EIF are related to two hydrological and chemical different source areas within the EIF basin. The seasonally increasing concentrations of ions during the third period of active layer development in both streams are explained by two processes: 1. increasing contribution of suprapermafrost groundwater to the stream runoff as a result of higher storage capacities of the active layer towards the end of the summer and 2. seasonally increasing ion concentrations of suprapermafrost groundwater with a longer residence time of water in the soil. Sulphate is the ion with the highest export rate for all streams. ln the EIF, the sum of Ca^2+ and SO4^2- is more than 90% of the total TDS exported. In the WIF/W, the percentage of Ca^2+ and SO4^2- exported is seasonally increasing from 83 to 90%. Overall, the rainstorm is the dominating event in both streams in terms of total export of TDS.