Linking long-term gully and river channel dynamics to environmental change using repeat photography (Northern Ethiopia)

Frankl, Amaury; Nyssen, Jan; Dapper, Morgan De; Haile, Mitiku; Billi, Paolo; Munro, R. Neil; Deckers, Jozef; Poesen, Jean

doi:10.1016/j.geomorph.2011.02.018

Cited by 112 publications

(126 citation statements)

References 49 publications

Supporting

Mentioning

118

Contrasting

Unclassified

Order By: Relevance

“…Such increased tree planting is qualified as 'forest transition', resulting from higher prices for wood products due to the scarcity of wood (the 'forest scarcity path') or higher wages and off-farm employment opportunities that encourage farmers to plant less labor-intensive tree crops (the 'economic development path') (Bensel, 2008;Rudel et al, 2005). Our observations regarding the decline in vegetation cover and conservation intensity from the 1970s-1980s are in line with the observation of gully development beginning from the 1960s and stabilization since the 1990s (Frankl et al, 2011). *** Figure 10 approximately here *** Although the study area ("northern Ethiopian Highlands") is frequently considered to be quite homogeneous, there are clear contrasts in climatic conditions (Table 2).…”

Section: Discussionsupporting

confidence: 79%

“…Subsets of the same dataset of repeated photographs have been used in qualitative and semi-quantitative analyses of changes in land use and management between two moments in time (Crummey, 1998;Hurni, 2005;Munro et al, 2008;Nyssen et al, 2009), to map historical land uses in periods before the existence of aerial photography (Meire et al, 2013), to analyze climate-induced changes to the upper treeline (Nievergelt, 1998), to calibrate the categorization of historical land uses as derived from satellite imagery (de Mûelenaere et al, 2013), or to study gully development (Frankl et al, 2011 2011 photographs were assigned a "zero" value (against which the older photographs were evaluated).…”

Section: Repeat Photographymentioning

confidence: 99%

See 1 more Smart Citation

Environmental conditions and human drivers for changes to north Ethiopian mountain landscapes over 145 years

Nyssen

Frankl

Haile

et al. 2014

Science of The Total Environment

Self Cite

View full text Add to dashboard Cite

As quantitative or spatially distributed studies of environmental change over truly long-term periods of more than 100 years are extremely rare, we re-photographed 361 landscapes that appear on historical photographs (1868-1994) within a 40,000 km² study area in northern Ethiopia. Visible evidence of environmental changes apparent from the paired photographs was analyzed using an expert rating system. The conditions of the woody vegetation, soil and water conservation structures and land management were worse in the earlier periods compared to their present conditions. The cover by indigenous trees is a notable exception: it peaked in the 1930s, declined afterwards and then achieved a second peak in the early 21 st century. Particularly in areas with greater population densities, there has been a significant increase in woody vegetation and soil and water conservation structures over the course of the study period. We conclude that except for an apparent upward movement of the upper tree limit, the direct human impacts on the environment are overriding the effects of climate change in the north Ethiopian highlands and that the northern Ethiopian highlands are currently greener than at any other time in the last 145 years.

show abstract

Section: Discussionsupporting

confidence: 79%

Section: Repeat Photographymentioning

confidence: 99%

Environmental conditions and human drivers for changes to north Ethiopian mountain landscapes over 145 years

Nyssen

Frankl

Haile

et al. 2014

Science of The Total Environment

Self Cite

View full text Add to dashboard Cite

show abstract

“…Among the numerous existing historical terrestrial photographs of Northern Ethiopia (Munro et al, 2008;Nyssen et al, 2009;Frankl et al, 2011), a subset was selected that covers early periods for which remote sensing techniques are no option.…”

Section: Repeat Photographymentioning

confidence: 99%

“…Two black-and-white photographs from 1942 and 1944 were taken by David Buxton while travelling in Ethiopia (Buxton, 1949 were not taken with the aim of being repeated, the camera locations were not permanently marked in the landscape. The repositioning was based on relocations carried out in 2007, by lining up landscape features in the fore-and background in a triangulation system (Nyssen et al, 2009;Frankl et al, 2011). Particular problems concerned atmospheric conditions and the lack of a clear, unobstructed view over the subject.…”

Section: Repeat Photographymentioning

confidence: 99%

Land use and cover dynamics in Africa since the nineteenth century: warped terrestrial photographs of North Ethiopia

et al. 2012

Self Cite

View full text Add to dashboard Cite

Quantitative research on land use and land cover (LUC) in Africa usually addresses the second half of the twentieth century, by using remote sensing data. Terrestrial photographs, which are available since 1868 in Ethiopia, are seldom used in a quantitative way. This paper presents a methodology that allows to produce land use and land cover (LUC) maps on the basis of old terrestrial photographs. Therefore, land use and land cover was investigated on historical and present-day photographs, and these interpretations were warped to the horizontal plane of the map. The resulting maps allow to gain better insights into LUC changes over a period of 140 years. The results show that woody vegetation increased strongly, together with an increase in built-up area. This occurred especially at the expense of bushland. The study validates pervious findings and shows that improved land management strategies in one of the world's most degraded areas can lead to environmental rehabilitation

show abstract

“…They cover large parts of the central and northern highlands, and form a unique dataset that allows the study of the status of the environment, in a period that until now was only accessible from terrestrial photographs (Nyssen et al 2009;Frankl et al 2011) or narratives (Pankhurst 1997). In total, ca.…”

Section: Introductionmentioning

confidence: 99%

Using image-based modelling (SfM–MVS) to produce a 1935 ortho-mosaic of the Ethiopian highlands

Frankl

Seghers

Stal

et al. 2014

International Journal of Digital Earth

Self Cite

View full text Add to dashboard Cite

Approximately 34,000 aerial photographs covering large parts of Ethiopia and dating back to 1935-41 have been recently recovered. These allow investigating environmental dynamics for a past period that until now was only accessible from terrestrial photographs or narratives. As the archive consists of both oblique and vertical aerial photographs that cover rather small areas, methods of image-based modelling were used to orthorectify the images. In this study, 9 vertical and 18 low oblique aerial photographs were processed as an ortho-mosaic, covering an area of 25 km², west of Wukro town in northern Ethiopia. Using 15 control points (derived from Google Earth), a RMSE of 28.5 m in X, 35.4 m in Y was achieved. These values can be viewed as optimal, given the relatively low resolution and poor quality of the imagery, the lack of metadata, the geometric quality of the Google Earth imagery and the recording characteristics. Land use remained largely similar since 1936, with large parts of the land being used as cropland or extensive grazing areas. Most remarkable changes are the strong expansion of the settlements as well as land management improvements. In a larger effort, ortho-mosaics covering large parts of Ethiopia in 1935-41 will be produced.

show abstract

Linking long-term gully and river channel dynamics to environmental change using repeat photography (Northern Ethiopia)

Cited by 112 publications

References 49 publications

Environmental conditions and human drivers for changes to north Ethiopian mountain landscapes over 145 years

Environmental conditions and human drivers for changes to north Ethiopian mountain landscapes over 145 years

Land use and cover dynamics in Africa since the nineteenth century: warped terrestrial photographs of North Ethiopia

Using image-based modelling (SfM–MVS) to produce a 1935 ortho-mosaic of the Ethiopian highlands

Contact Info

Product

Resources

About