Urban Riparian Areas: Ecological And Streamside-Ordinance Assessments
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Streamside protection ordinances have been established in many urbanizing areas; however, there has been a paucity of assessments of the effectiveness of such ordinances. A quantitative assessment of the ecological impairments in an urban river system can provide a key component in a basin-scale management plan. A study was conducted in the Blue River Basin, Kansas and Missouri, to determine the effectiveness of streamside ordinances and assess the temporal and spatial changes in the ecological health of the river. Study objectives included the determination of the vegetation change within ordinance protected and non ordinance protected areas within the study area, and a spatial and temporal assessment of ecological impairment through the development of a quantitative index—the Ecological Index of Urban Stream Health (EUISH). SPOT imagery was used to classify landscape changes over time (1992 through 2012), across multiple jurisdictions, and pre- and post-ordinance implementation periods. The GIS-based EIUSH included eight spatial data layers representing five environmental categories including physical habitat, hydrology, water quality, land use/land cover, and aquatic communities. Results of the overall effectiveness of streamside ordinance protection indicated tree cover declined 12.5%, grass cover declined 9.7%, and developed land increased 22.9% during the 20-year analysis period. These results indicate that streamside ordinances along the Blue River need modifications in order to be more effective at limiting land use and land cover change. The mean EIUSH score was about 45 (0-100 scale) and ranged from 25 to 82. Index scores differed substantially by river reach and with time, with the lowest scores determined for the lower part of the basin and a major tributary, Indian Creek, and the highest scores determined for the upstream part of the basin. Temporal updates of EIUSH scores indicated the greatest index decline was in the upper Blue River—the area of highest ecological integrity in the basin. The index can be used to spatially target and maintain the riparian areas of highest ecological integrity. Alternatively, the index can be used to spatially identify areas of highest ecological impairment, and the likely causes of the impairment, so that the conditions can be addressed.
Table of Contents
Introduction -- Literature review -- Methods -- Results -- Discussion and conclusion