Riparian vegetation and channel change in response to river regulation: a comparative study of regulated and unregulated streams in the Green River Basin, USA

Merritt, David M.; Cooper, David J.

doi:10.1002/1099-1646(200011/12)16:6<543::aid-rrr590>3.0.co;2-n

Cited by 316 publications

(299 citation statements)

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“…Likewise, vegetation changes have been studied both in riverine and other environments, many studies using satellite imagery (Bertoldi, Drake, & Gurnell, 2011) but many, especially on decadal timescales, have used aerial photographs, as here (Dixon & Johnson, 1999;Garófano-Gómez et al, 2013;Gonzalez, Gonzalez-Sanchis, Cabezas, Comin, & Muller, 2010;Kondolf, Piegay, & Landon, 2007;Lunt, Winsemius, McDonald, Morgan, & Dehaan, 2010;Yang & Tien, 2010). Increases in woody riparian area have been found but many of the cases are associated with change in river regime (Dixon & Johnson, 1999;Johnson, 1994;Perona, Molnar, Savina, & Burlando, 2009), especially due to dam control (Dixon, Johnson, Scott, Bowen, & Rabbe, 2012;Gonzalez et al, 2010;Merritt & Cooper, 2000). Other causes of change such as land-use management impacts have been investigated or demonstrated (Sawtschuk, Delisle, Mesmin, & Bernez, 2014), as well as climatic and natural hydrologic variations (e.g.…”

Section: Introductionmentioning

confidence: 99%

Evidence of increase in woody vegetation in a river corridor, Northwest England, 1984–2007

Hooke

Chen

2015

Journal of Maps

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Based on observations on rivers in England over a 30-year period, it was hypothesised that the extent of woody vegetation in riparian areas has increased in many locations. Methods to map and measure changes in vegetation cover from aerial photographs were developed and tested on a 5 km reach of the River Dane in Northwest England. Riparian vegetation was divided into seven classes, and these were mapped from aerial photographs of four dates, 1984, 1996, 2001 and 2007. The results indicate an increase from 9% woody vegetation cover in the river corridor in 1984 to 32% cover in 2007, with a 40-fold increase in areas of mature woody vegetation. The results have implications for river processes, because of effects on bank erosion and sediment supply, and for land management policies, with grazing control hypothesised to be a major cause of the changes.

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Section: Introductionmentioning

confidence: 99%

Evidence of increase in woody vegetation in a river corridor, Northwest England, 1984–2007

Hooke

Chen

2015

Journal of Maps

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“…Anthropogenic activities, such as agriculture and livestock, mining, industry, transportation and communication, and urbanisation, have caused alteration or degradation of many riparian environments (e.g. Robertson and Rowling, 2000;Merritt et al, 2000;EPA 1999;Gurnell, 1997). If left unabated, the continuous misuse of these resources could bring further ecological problems and economic losses.…”

Section: Introductionmentioning

confidence: 99%

Mapping and analysis of changes in the riparian landscape structure of the Lockyer Valley catchment, Queensland, Australia

Apan

Raine

Paterson

2002

Landscape and Urban Planning

134

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A case study of the Lockyer Valley catchment in Queensland, Australia, was conducted to develop appropriate mapping and assessment techniques to quantify the nature and magnitude of riparian landscape structural changes within a catchment. The study employed digital image processing techniques to produce land cover maps from the 1973 and 1997 Landsat imagery. Fixed and variable width buffering of streams were implemented using a geographic information system (GIS) to estimate the riparian zone and to subsequently calculate the landscape patterns using the Patch Analyst (Grid) program (a FRAGSTATS interface). The nature of vegetation clearing was characterised based on land tenure, slope and stream order. Using the Pearson chi-square test and Cramer's V statistic, the relationships between the vegetation clearing and land tenure were further assessed. The results show the significant decrease in woody vegetation areas mainly due to conversion to pasture. Riparian vegetation corridors have become more fragmented, isolated and of much smaller patches. Land tenure was found to be significantly associated with the vegetation clearing, although the strength of association was weak. The large proportion of deforested riparian zones within steep slopes or first-order streams raises serious questions about the catchment health and the longer term potential for land degradation by upland clearing. This study highlights the use of satellite imagery and geographic information systems in mapping and analysis of landscape structural change, as well as the identification of key issues related to sensor spatial resolution, stream buffering widths, and the quantification of land transformation processes.

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“…Harris et al (1987) noted that after water diversion, the changes in the herb stratum tend to be the most pronounced, and Azami et al (2004) observed that the reduced flood peaks below a dam led to the expansion of riparian forest area and its transition into later successional stages. Similar shifts were detected along the Green River, USA, by Merritt and Cooper (2000), 37 years after dam construction, indicating the eventual replacement of Populus-dominated riparian forest by drought-tolerant desertic shrubs and the enlargement of in-channel fluvial marshes. Similarly, many Mediterranean rivers have experienced a loss of riparian woodland, but few studies have attempted to spatially quantify that loss and its historical timing (Muller et al, 2002).…”

Section: Interpreting the Observed Riparian Dynamicsmentioning

confidence: 98%

Six decades of changes in the riparian corridor of a Mediterranean river: a synthetic analysis based on historical data sources

et al. 2012

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(2012). Six decades of changes in the riparian corridor of a Mediterranean river: A synthetic analysis based on historical data sources. Ecohydrology, 6 (4): 536¿553. doi:10.1002/eco.1330.1 This is a pre-copyedited, author-produced PDF version following peer review of the article: Garófano-Gómez, V., F. Martínez-Capel, W. Bertoldi, A. Gurnell, J. Estornell, F. Segura-Beltrán. 2013 ABSTRACTRiparian corridors in semi-arid Mediterranean environments are ecosystems of high biodiversity and complexity. However, they are threatened because of high levels of human intervention. River damming and related flow manipulation is considered as one of the most prominent human impacts on riparian corridors. This study combines historical time series information on river flows and their human manipulation, historical aerial images depicting changes in riparian land cover and ground observations of the species -age composition and morphology of the riparian corridor of a Mediterranean river (the Mijares River, Eastern Spain) over the last 60 years. In this sense, we explored how to integrate information from a wide variety of data sources, and we extracted a variety of indices and undertook analyses that identified and summarized spatio-temporal changes in riparian structure and in the driving flow processes.Results revealed an increase in the cover and density of woody vegetation and a decrease in bare sediment areas (essential for recruitment of riparian pioneer species), with a synchronous reduction in the complexity of the riparian corridor of the middle reaches of the Mijares River. These vegetation changes have accompanied a decrease in the magnitude and variability of river flows over the last six decades, with higher severity since dam closure. This study illustrates the effectiveness of combining disparate historical data sources and the effectiveness of processing these sources to extract informative metrics that can improve the understanding and management of riparian systems.

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Riparian vegetation and channel change in response to river regulation: a comparative study of regulated and unregulated streams in the Green River Basin, USA

Cited by 316 publications

References 50 publications

Evidence of increase in woody vegetation in a river corridor, Northwest England, 1984–2007

Evidence of increase in woody vegetation in a river corridor, Northwest England, 1984–2007

Mapping and analysis of changes in the riparian landscape structure of the Lockyer Valley catchment, Queensland, Australia

Six decades of changes in the riparian corridor of a Mediterranean river: a synthetic analysis based on historical data sources

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