Runoff processes in glacier and paramo catchments in the Andean region are of interest as they are vitally important to serve the water needs of surrounding communities. Particularly in Northern Ecuador, the runoff processes are less well-known due to the high variability of precipitation, young volcanic ash soil properties, soil moisture dynamics and other local factors. Previous studies have shown that the melting of glaciers contributes to runoff generation and that the paramo ecosystem plays an important role in regulating runoff during periods of low precipitation. Data collection and experimental investigations were carried out in a catchment of 15.2 km(2) and altitude ranging between 4000 and 5700 m above sea level. Environmental tracers and hydrochemical catchment characterization were used for identifying runoff sources and their respective contributions during dry and wet conditions. Dry conditions are defined as periods where precipitation was absent for at least three consecutive days and wet conditions imply rainfall events. This study highlights the importance of the paramo on contributing to total runoff during baseflow (70% of total runoff) and the capacity of the paramo to dissipate the stream energy and buffer the peak flow during rainfall conditions. Electrical conductivity together with stable isotopes were identified as conservative tracers that characterize the end-member concentrations.

High Arctic river responses to changing hydroclimatic and landscape processes are poorly understood. In non-glacierized basins, snowmelt and rainfall generate river discharge, which provides first order control over fluxes. Further factors include the seasonality of precipitation, seasonal active layer development, and permafrost disturbance. These controls were evaluated in terms of sedimentary and biogeochemical fluxes from paired catchments at Cape Bounty, Melville Island, Nunavut during 20062009. Results indicate that the source of runoff can be more important than the amount of runoff for sediment, solutes, and organic yields. Although the snowmelt period is typically the most important time for these yields, heavy late summer precipitation events can create disproportionately large yields. Rainfall increases yields because it hydrologically connects areas otherwise isolated. Inorganic solute yields from late summer rainfall are higher because the thick active layer maximizes hydrologic interactions with mineral soils and generates high solute concentrations. Results also indicate that while the catchments are broadly similar, subtle topographic differences result in important inter-catchment differences in runoff and suspended and dissolved loads. The East watershed, which had less extensive permafrost disturbance, consistently had higher concentrations of dissolved solids. These higher dissolved fluxes cannot therefore be explained by thermokarst features, but rather by deeper active layer development, due to a greater proportion of south-facing slopes. Although warm temperatures in 2007 led to extensive active layer disturbance in the West watershed, because the disturbances were largely hydrologically disconnected, the total disturbed area was small, and inter-annual variability in discharge was high, there was no detectable response in dissolved loads to disturbances. Sediment availability increased after 2007, but yields have largely returned to pre-disturbance levels. Results indicate that seasonality and frequency-magnitude characteristics of projected increases in precipitation must be considered along with active layer changes to predict the fluvial sedimentary and biogeochemical response to regional climate change. Copyright (c) 2011 John Wiley & Sons, Ltd.

In the lake-rich tundra uplands east of the Mackenzie Delta, almost one in ten lakes has been affected by retrogressive thaw slumping. In this study, we assessed water chemistry for 34 slump-affected and 39 undisturbed upland lakes across this region and found that environmental factors typically evoked to explain variation in tundra lake water quality including surficial geology and proximity to the treeline or coast were subordinate to the main driver, permafrost degradation. Thaw slump-affected lakes had elevated ionic concentrations and water clarity in comparison with undisturbed lakes. The strength of the ionic impact was positively associated with the proportion of catchment affected by slumping and inversely related to disturbance age. Slumping did not have a significant effect on total organic carbon (TOC) concentrations, although Water clarity increased significantly with decreasing age of disturbance. In lakes undisturbed by slumping. fire-induced active-layer deepening had a delectable influence on lake water ionic strength. Surficial deposits influenced TOC concentrations with the highest concentrations and colour in undisturbed lakes with lacustrine catchments. In a warming Arctic, thermokarst processes may increase in importance as a driver of ionic chemistry and optical properties of small lakes and ponds, and shifts in aquatic food webs can be anticipated. Copyright (C) 2009 John Wiley & Sons, Ltd. and Her Majesty the Queen in right of Canada.

Chemical data are presented for water from 22 lakes in small upland catchments (<20 ha) between Inuvik and Richards Island, Northwest Territories, Canada. Eleven of the basins appear pristine and I I are affected by thermokarst slumping. The mean dissolved organic carbon (DOC) concentration of the pristine lakes (16.3 mg/l) is greater than the mean concentration of lakes disturbed by thermokarst slumping (10.5 mg/l). In pristine lakes, mean concentrations of Ca, Mg and SO4 are 9.6, 3.6 and 11.1 mg/l, but in lakes affected by thermokarst, mean concentrations are 72.6, 26.8 and 208.2 mg/l, respectively. Soluble materials released from degrading permafrost are transported to lakes by surface runoff, elevating concentrations in lake water. The percentage of total basin area influenced by thermokarst is positively associated with ionic concentrations in lake water and inversely related to DOC. Thermokarst occupying as little as 2% of catchment area may modify the chemistry of lake water, and water quality may remain affected for several decades after slump development has ceased. Aerial photographs indicate that 5 to 15% of all lakes and ponds in four 49 km(2) areas between Inuvik and Richards Island are small (median size <2 ha) with catchments affected by thermokarst. Copyright (C) 2005 John Wiley & Sons, Ltd.