Using land cover information in assessing the ecosystem health of streams

Land use in a catchment area is critical to understanding how human activities are impacting streams. Catchment land cover is typically quantified as proportions of land use types, but such proportions do not quantify where land use patches are relative to the stream.

This paper discusses the merit of land use position metrics for application to stream assessments.

Landscape configuration metrics (LCMs) are often used in stream assessments to describe land use position, but we argue these metrics should be avoided due to: (1) poor description of catchment land cover; (2) inconsistency, and; (3) missing link between valley and stream. Inverse-distance-weighted metrics (IDWs) explicitly quantify the position of land use patches relative to the stream, and thus are conceptually grounded in empirical evidence that the effect of land use is inversely related to its distance from the stream. Hydrologically active IDWs (HA-IDWs) further refine IDWs by quantifying the proximity of land use to hydrologic pathways connecting a stream to its catchment.

We recommend IDW metrics become the standard method to describe catchment land use and its effect on stream conditions and that HA-IDW metrics be used when the required data is available.