Abstract

This study was carried out as part of an investigation of water and sediment budgets in an ephemeral catchment in Dinosaur Provincial Park badlands, Alberta. These badlands have developed in Cretaceous mudstones, siltstones, and sandstones, with some glacial and postglacial surficial deposits. Study objectives were (i) to identify major solute sources, (ii) to show how these change with storm characteristics, and (iii) to assess the proportion of solutes in the total stream budget. Field examination, rainfall-simulation tests, and laboratory experiments showed marked variations in solute production on different lithologic surfaces. This information, when combined with data on threshold precipitation for runoff production from previous experiments, made it clear that solute production in the catchment is significantly influenced by storm characteristics. Observations indicate that in brief, low-intensity storms, runoff occurs only on sandstone, miniature-pediment, and stream-channel surfaces. Solute production on these surfaces is limited and is dominated by flushing of salts previously precipitated on the surface. In high-intensity or prolonged storms, runoff also occurs on mudstone surfaces and from subsurface tunnels. In both cases solute production is higher and increases with storm duration because of progressive mudstone dispersion. During the 12 storms monitored, the average stream-solute concentration was 308 mg L−1, which is approximately 1.4% of the total stream load.

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