Geospatial Analysis of Riparian Condition in Lockhart, Texas: An Investigation of the Index of Riparian Integrity
Date
2023-05
Authors
Acosta, Shelby
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Abstract
The City of Austin Watershed Protection Department has developed the Index of Riparian Integrity to assess the health of its environmental resources. The Index of Riparian Integrity uses a geographic information system and remotely sensed data to (1) calculate the relative amount of canopy cover, impervious cover, and pervious cover to estimate riparian health and floodplain function and (2) prioritize restoration efforts. The purpose of this study was to assess (1) the application of the Index of Riparian Integrity on a watershed outside of Austin’s city limits and (2) the existing condition of the riparian area using the Index of Riparian Integrity in the Town Branch Watershed in Lockhart, Texas. The Index of Riparian Integrity, using the National Land Cover Database layers, gave a representative overview of Town Branch’s riparian conditions when compared to the aerial imagery of the area with areas of greater development receiving lower scores and forested areas receiving higher scores. The Index of Riparian Integrity cannot identify more subtle differences between vegetation. All non-canopy vegetation is treated as the same quality, which means that invasive vegetation or mowed lawns receive the same score as high-quality wetland vegetation. This process also cannot capture erosion in a stretch of riparian area that might have otherwise “functional” land uses according to the Index of Riparian Integrity categorization. Due to the resolution of the National Land Cover Database layers used, certain features, like thinner railroads, are not captured in the analysis, which might lead to higher than appropriate Index of Riparian Integrity scores for certain areas of the watershed. While this methodology cannot replace in situ riparian assessments, the Index of Riparian Integrity allows decision makers to develop a watershed-wide assessment of its riparian condition in a fraction of the time that it would have taken to do the same in-person.
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Keywords
riparian, watershed, GIS, restoration
Citation
Acosta, S. (2023). Geospatial analysis of riparian condition in Lockhart, Texas: An investigation of the index of riparian integrity. Masters of Applied Geography, Texas State University, San Marcos, Texas.