Abstract:

Two sets of percent land data in flow paths and adjacent reference areas of two diversions in Louisiana (Davis Pond and Caernarvon) were calculated from two sources of public satellite imagery data (see Methods) from 1985-2014 in order to test the hypothesis that river diversions stimulate land building. Additionally, data from another public source (see Methods) was compiled as input for a BACI (before-after control-impact) analysis. Land acreage and percent land data were calculated for 1985 to 2016, with values being designated as being inside or outside of the flow path of the Caernarvon diversion. This dataset supports the publication by Turner, R. Eugene, Michael Layne, Yu Mo, and Erick M. Swenson. 2019. Net land gain or loss for two Mississippi River diversions: Caernarvon and Davis Pond. Restoration Ecology, 27(6) 1231-1240. DOI: 10.1111/rec.13024

Suggested Citation:

Turner, R. Eugene. 2021. Dataset for: Net land gain or loss for two Mississippi River diversions: Caernarvon and Davis Pond. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/5RW07G3Y

Publications:

Turner, R. E., Layne, M., Mo, Y., & Swenson, E. M. (2019). Net land gain or loss for two Mississippi River diversions: Caernarvon and Davis Pond. Restoration Ecology, 27(6), 1231–1240. doi:10.1111/rec.13024

Purpose:

To determine the effect of river diversions on restoration in southern Louisiana.

Data Parameters and Units:

Worksheet Diversion % land: Percent land data calculated from two sets of source data (Data 1, Data 2) for diversion and reference sites in four areas (Davis Pond, Naomi, Pointe à la Hache, Caernarvon) from 1985 to 2014. Variables presented for each area are: Year: In decimal year format; Reference Data 1: Percent land calculated for reference area in Data 1; Reference Data 2: Percent land calculated for reference area in Data 2; Diversion Data 1: Percent land calculated for diversion area in Data 1; Diversion Data 2: Percent land calculated for diversion area in Data 2; Note that the Caernarvon location has two Reference areas (Location a and Location b). Worksheet CRMS DATA: Month: In numeric format; Day: In numeric format; Year: In numeric format; DEC_YEAR: In decimal year format; CRMS_ID: Identifier assigned by the monitoring program that published the source data; Latitude: In decimal degrees; Longitude: In decimal degrees; LAND_ACRES: Number of acres for which percent plant cover was calculated; LAND_PERCENT: Percent land calculated from CRMS plant cover data; BASIN: Geographic description of study area; Flow path: User defined designation for whether site was located in the Caernarvon flow path (diversion) or outside of the Caernarvon flow path (adjacent).

Methods:

Three sets of data were compiled to investigate the hypothesis that river diversions stimulate land building (results published in Turner, R. Eugene, Michael Layne, Yu Mo, and Erick M. Swenson, 2019. Net land gain or loss for two Mississippi River diversions: Caernarvon and Davis Pond. Restor Ecol, vol 27, Issue 6, https://onlinelibrary.wiley.com/doi/abs/10.1111/rec.13024”): 1) Data 1 (contained in the Worksheet Diversion % land): Remotely sensed imagery analysis that estimated the percent land in multiple years relative to 1985 (land area was converted to the percent of land in 1985 as a common starting point, which was normalized (=100%)). Source data can be found in GRIIDC datasets (10.7266/n7513w97, 10.7266/N7222RVS, 10.7266/N7X928DB, 10.7266/N71834KW, 10.7266/N7SJ1HPM, 10.7266/N7NS0RZW, 10.7266/N7J10178, 10.7266/N7D798H0, 10.7266/N7WH2N25, 10.7266/N78G8HTQ, 10.7266/N74T6GFT, 10.7266/N7125QRV, 10.7266/N7B56GNT, 10.7266/N7RR1W90, 10.7266/N7W9578Z, 10.7266/N7V98651, 10.7266/N7F47M2T, 10.7266/N7N014MD, 10.7266/N7PN93J0, 10.7266/N7RJ4GJ7, 10.7266/N7MS3QTH, 10.7266/N7H1303W, 10.7266/N7CJ8BK4, 10.7266/N7C827DM, 10.7266/N77S7KVD, 10.7266/N7GX491R) and methodologies in “Mo Y, Kearney MS, Turner RE (2019) Feedback of coastal marshes to climate change: long‐term phenological shifts. Ecology and Evolution 9:1–13” and “Turner, R. E., Layne, M., Mo, Y., & Swenson, E. M. (2019). Net land gain or loss for two Mississippi River diversions: Caernarvon and Davis Pond. Restor Ecol, vol 27, Issue 6, https://onlinelibrary.wiley.com/doi/abs/10.1111/rec.13024”. 2) Data 2 (contained in the Worksheet Diversion % land): Remotely sensed imagery analysis that estimated the percent land in multiple years (1985 to 2015), described by Couvillion et al. Source data and methodology can be found at https://www.sciencebase.gov/catalog/item/5a67a8cde4b06e28e9c57150. 3) Compiled mean ± 1 SEM (standard error of the mean) measurements of plant cover values from 1985 to 2016, for 14 sites within in the Caernarvon flow path and 17 sites outside of the flow path (contained in the Worksheet CRMS Data). Source data was obtained from the Coastwide Reference Monitoring System (CRMS) administered by Louisiana’s Coastal Protection and Restoration Authority at https://www.lacoast.gov/crms/Home.aspx.

Error Analysis:

Data 1 and Data 2 define different kinds of land loss rates. Data 1 is from 1985 to 2014 and Data 2 is from 1985 to 2016. Data 2 includes relatively less floating vegetation classified as land than do land estimates using Data 1 because seasonal and annual changes in floating vegetation within 1 pixel are not measured as land loss unless they are also observed in the next aerial image. This methodological difference results in a more conservative estimate of the percent land for Data 2 compared to Data 1 and reduces variance from year to year.

Individual Files: