An investigation of the interrelationships among streamflow, lake level, climate and land use, with particular reference to the Battle River Basin, Alberta
Streamflow records exist for the Battle River near Ponoka, Alberta from 1913 to 1931 and from 1966 to the present. Analysis of these two periods has indicated that streamflow in the month of April has remained constant while mean flows in the other months have significantly decreased in the more recent period. In contrast, streamflow in the same periods at Battleford, Saskatchewan has tended to increase. This indicates that the regime of the Battle River above Ponoka has changed. From the analysis of monthly and daily precipitation recorded at Lacombe and Wetaskiwin, Alberta, it was concluded that April, May, and September flows for the Battle River near Ponoka are probably responding to precipitation characteristics. No clear relationship between precipitation and runoff is indicated for June, July, and August. From Alberta census data it has been demonstrated that the amount of deforestation in the basin upstream from Ponoka has probably had no significant effect on runoff. It has been postulated that a decrease in summer runoff may be related to higher growing season temperatures and the replacement of natural pasture by improved pasture and field crops. This decrease may be related to higher transpiration rates, increased infiltration potential and increased soil moisture evaporation. Many of the lakes in Central Alberta appear to be responding to regional effects of climate and land use. Although poor correlations exist between lake levels and Battle River flows, significant. correlations in mean annual lake levels occur between Gull Lake and Buffalo, Sylvan, Pigeon, and Wabamun Lakes in the 1956 to 1966 period and between Gull Lake and Sylvan Lake only in the 1967 to 1978 period. It has been postulated that the land use changes influencing streamflow also are affecting lake levels. Variations in elevation for Gull Lake (and possibly many of the other lakes in the region) do not appear to be related to artificial drainage, erosion of an outlet channel, buried valleys, bedrock fractures, or seismic exploration.