Presentation Title

A Multi-Scale Assessment of Urban Streams and the Influence of the Urban Environment on Aquatic Health and Function

Abstract

The riparian areas along flowing waterbodies are sensitive environments that are closely linked to stream health and in the urban environment and riparian zones are often impacted by the pollutants, development and environmental alterations that occur in a city. For this study, I worked with the City of Portland to determine how the characteristics of the landscape in buffer areas (of varying widths) along urban streams influenced the overall health of the streams. I utilized stream health data (represented by macroinvertebrate IBI) that was collected from 59 randomly distributed stream monitoring sites located in Portland, OR and analyzed it in relation to 21 urban landscape characteristics that included variables relating to land use, impervious surfaces, vegetation, and urban infrastructure. Buffer areas were digitally generated around a 1-km stretch upstream of each monitoring sites with widths ranging from 15 to 500 ft. I used a random forest analysis algorithm to decide on the best combination of variables to use in regression models. Through a process of model refinement and analysis I determined that 200 and 500 ft models buffer models were best used to analyze the data range. In the two final models, I found that the length of piped stream and the mean canopy height were the best predictors of stream health (R2 mean of .567 between the two models). In both models, the piped stream length area was negatively correlated with stream health while a greater mean canopy height in the buffer area was positively correlated with stream health.

Subjects

GIS / modeling, Hydrology, Land/watershed management

Persistent Identifier

https://archives.pdx.edu/ds/psu/33832

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A Multi-Scale Assessment of Urban Streams and the Influence of the Urban Environment on Aquatic Health and Function

The riparian areas along flowing waterbodies are sensitive environments that are closely linked to stream health and in the urban environment and riparian zones are often impacted by the pollutants, development and environmental alterations that occur in a city. For this study, I worked with the City of Portland to determine how the characteristics of the landscape in buffer areas (of varying widths) along urban streams influenced the overall health of the streams. I utilized stream health data (represented by macroinvertebrate IBI) that was collected from 59 randomly distributed stream monitoring sites located in Portland, OR and analyzed it in relation to 21 urban landscape characteristics that included variables relating to land use, impervious surfaces, vegetation, and urban infrastructure. Buffer areas were digitally generated around a 1-km stretch upstream of each monitoring sites with widths ranging from 15 to 500 ft. I used a random forest analysis algorithm to decide on the best combination of variables to use in regression models. Through a process of model refinement and analysis I determined that 200 and 500 ft models buffer models were best used to analyze the data range. In the two final models, I found that the length of piped stream and the mean canopy height were the best predictors of stream health (R2 mean of .567 between the two models). In both models, the piped stream length area was negatively correlated with stream health while a greater mean canopy height in the buffer area was positively correlated with stream health.