Riparian Area Changes in Greenness and Water Use on the Lower Colorado River in the USA from 2000 to 2020

Nagler, PL; Barreto-Muñoz, A; Borujeni, SC; Nouri, H; Jarchow, CJ; Didan, K

Riparian Area Changes in Greenness and Water Use on the Lower Colorado River in the USA from 2000 to 2020

Nagler, PL Barreto-Muñoz, A Borujeni, SC Nouri, H Jarchow, CJ Didan, K

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Publisher:: MDPI AG
Publication Type:: Journal Article
Citation:: Remote Sensing, 2021, 13, (7), pp. 1332
Issue Date:: 2021-03-31

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Field	Value	Language
dc.contributor.author	Nagler, PL
dc.contributor.author	Barreto-Muñoz, A
dc.contributor.author	Borujeni, SC
dc.contributor.author	Nouri, H
dc.contributor.author	Jarchow, CJ
dc.contributor.author	Didan, K
dc.date.accessioned	2022-04-29T21:08:10Z
dc.date.available	2022-04-29T21:08:10Z
dc.date.issued	2021-03-31
dc.identifier.citation	Remote Sensing, 2021, 13, (7), pp. 1332
dc.identifier.issn	2315-4675
dc.identifier.issn	2072-4292
dc.identifier.uri	http://hdl.handle.net/10453/156829
dc.description.abstract	<jats:p>Declines in riparian ecosystem greenness and water use have been observed in the delta of the Lower Colorado River (LCR) since 2000. The purpose of our case study was to measure these metrics on the U.S. side of the border between Hoover and Morelos Dams to see if declining greenness was unique to the portion of the river in Mexico. In this case study, five riparian reaches of the LCR from Hoover to Morelos Dam since 2000 were studied to evaluate trends in riparian ecosystem health. We measure these riparian woodlands using remotely sensed measurements of the two-band Enhanced Vegetation Index (EVI2; a proxy for greenness); daily evapotranspiration (ET; mmd−1) using EVI2 (ET(EVI2)); and an annualized ET based on EVI2, the Phenology Assessment Metric (PAM ET), an annualized ET using Landsat time-series. A key finding is that riparian health and its water use has been in decline since 2000 on the U.S. portion of the LCR, depicting a loss of green vegetation over the last two decades. EVI2 results show a decline of −13.83%, while average daily ET(EVI2) between the first and last decade had a decrease of over 1 mmd−1 (−27.30%) and the respective average PAM ET losses were 170.91 mmyr−1 (−17.95%). The difference between the first and last five-year periods, 2000–2005 and 2016–2020, showed the largest decrease in daily ET(EVI) of 1.24 mmd−1 (−32.61%). These declines come from a loss in healthy, green, riparian plant-cover, not a change in plant water use efficiency nor efficient use of managed water resources. Our results suggest further deterioration of biodiversity, wildlife habitat and other key ecosystem services on the U.S. portion of the LCR.</jats:p>
dc.language	en
dc.publisher	MDPI AG
dc.relation.ispartof	Remote Sensing
dc.relation.isbasedon	10.3390/rs13071332
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	0203 Classical Physics, 0406 Physical Geography and Environmental Geoscience, 0909 Geomatic Engineering
dc.title	Riparian Area Changes in Greenness and Water Use on the Lower Colorado River in the USA from 2000 to 2020
dc.type	Journal Article
utslib.citation.volume	13
utslib.for	0203 Classical Physics
utslib.for	0406 Physical Geography and Environmental Geoscience
utslib.for	0909 Geomatic Engineering
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
utslib.copyright.status	open_access	*
dc.date.updated	2022-04-29T21:07:14Z
pubs.issue	7
pubs.publication-status	Published online
pubs.volume	13
utslib.citation.issue	7

Abstract:

Declines in riparian ecosystem greenness and water use have been observed in the delta of the Lower Colorado River (LCR) since 2000. The purpose of our case study was to measure these metrics on the U.S. side of the border between Hoover and Morelos Dams to see if declining greenness was unique to the portion of the river in Mexico. In this case study, five riparian reaches of the LCR from Hoover to Morelos Dam since 2000 were studied to evaluate trends in riparian ecosystem health. We measure these riparian woodlands using remotely sensed measurements of the two-band Enhanced Vegetation Index (EVI2; a proxy for greenness); daily evapotranspiration (ET; mmd−1) using EVI2 (ET(EVI2)); and an annualized ET based on EVI2, the Phenology Assessment Metric (PAM ET), an annualized ET using Landsat time-series. A key finding is that riparian health and its water use has been in decline since 2000 on the U.S. portion of the LCR, depicting a loss of green vegetation over the last two decades. EVI2 results show a decline of −13.83%, while average daily ET(EVI2) between the first and last decade had a decrease of over 1 mmd−1 (−27.30%) and the respective average PAM ET losses were 170.91 mmyr−1 (−17.95%). The difference between the first and last five-year periods, 2000–2005 and 2016–2020, showed the largest decrease in daily ET(EVI) of 1.24 mmd−1 (−32.61%). These declines come from a loss in healthy, green, riparian plant-cover, not a change in plant water use efficiency nor efficient use of managed water resources. Our results suggest further deterioration of biodiversity, wildlife habitat and other key ecosystem services on the U.S. portion of the LCR.

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