Terrasses alluviales et terrasses agricoles. Première approche des comblements sédimentaires et de leurs aménagements agricoles depuis 5000 av. n. è. à Wakarida (Éthiopie)

Blond, Ninon; Jacob-Rousseau, Nicolas; Callot, Yann

doi:10.4000/geomorphologie.12258

Cited by 9 publications

(11 citation statements)

References 78 publications

(68 reference statements)

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“…Despite its strong relief, 40.2% of the Giba catchment is classified as very suitable for agriculture and another 25.1% as moderately suitable. On the other hand, long-standing cropping and soil erosion in this mountainous catchment [3, 4] have led to the presence of large unsuitable areas (26% of the area is covered by bare rock and Leptosols). Furthermore, relatively less erodible clay and sand dominate the soil texture; the high rock fragment contents of topsoils after prolonged tillage and erosion also provide a partial protection against soil erosion [122–124].…”

Section: Discussionmentioning

confidence: 99%

“…In the Giba catchment (5133 km 2 ), north Ethiopia, poverty has been largely attributed to insufficient crop production [1, 2]. Soil degradation in this area became important when humans started deforestation almost 5000 years ago [3, 4]. The resulting reduced soil protection by vegetation cover, combined with steep slopes and erosive rainfall led to excessive soil erosion [5, 6].…”

Section: Introductionmentioning

confidence: 99%

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Understanding spatial patterns of soils for sustainable agriculture in northern Ethiopia’s tropical mountains

et al. 2019

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Knowledge of the geographical distribution of soils is indispensable for policy and decision makers to achieve the goal of increasing agricultural production and reduce poverty, particularly in the Global South. A study was conducted to better understand the soilscapes of the Giba catchment (900–3300 m a.s.l.; 5133 km2) in northern Ethiopia, so as to sustain soil use and management. To characterise the chemical and physical properties of the different benchmark soils and to classify them in line with the World Reference Base of Soil Resources, 141 soil profile pits and 1381 soil augerings at representative sites were analysed. The dominant soil units identified are Leptosol and bare rock (19% coverage), Vertic Cambisol (14%), Regosol and Cambisol (10%), Skeletic/Leptic Cambisol and Regosol (9%), Rendzic Leptosol (7%), Calcaric/Calcic Vertisol (6%), Chromic Luvisol (6%) and Chromic/Pellic Vertisol (5%). Together these eight soil units cover almost 75% of the catchment. Topography and parent material are the major influencing factors that explain the soil distribution. Besides these two factors, land cover that is strongly impacted by human activities, may not be overlooked. Our soil suitability study shows that currently, after thousands of years of agricultural land use, a new dynamic equilibrium has come into existence in the soilscape, in which ca. 40% of the catchment is very suitable, and 25% is moderately suitable for agricultural production. In view of such large suitable areas, the Giba catchment has a good agricultural potential if soil erosion rates can be controlled, soil fertility (particularly nitrogen) increased, available water optimally used, and henceforth crop yields increased.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Understanding spatial patterns of soils for sustainable agriculture in northern Ethiopia’s tropical mountains

et al. 2019

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“…However, we noted a certain synchronism in the phases we were able to identify: an incision around 5900 -5500 years ago (May Weini and May Ayni), a resumption of sedimentation around 2000 years ago and an incision affecting the whole watershed, over the last 400 years (Blond et al, 2018;Blond, 2019). Currently, channel entrenchment in alluvial floors is partly masked by terrace cultivation which started to expand in the last quarter of the 20 th century (Blond et al, 2018;Blond, 2019).…”

Section: Synthesis Of the Radiocarbon Ages Obtainedmentioning

confidence: 82%

“…The dry season extends from October to January and is called bega. Mean annual rainfall in the area ranges from 379 mm/yr to 575 mm/yr, and kiremt rains represent between 57 and 62% of the total rainfall (Blond et al, 2018).…”

Section: Geographical Archaeological and Geoarchaeological Context 1 Geographical Settingsmentioning

confidence: 99%

“…Terraces are signs of the adaptation of today's populations to a challenging environment: soil and water resources being scarce, the terrace walls are built to enhance agricultural production by concentrating water on the plots and protecting the soil from erosion (Figure 3). Studies have shown that these terraces are of recent construction (Blond et al, 2018;Blond, 2019), but the sedimentary deposits on which they rely provide records of changes in the environment and of the impacts of human activities on the landscape.…”

Section: Geographical Archaeological and Geoarchaeological Context 1 Geographical Settingsmentioning

confidence: 99%

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From section to landscape(s): reconstructions of environmental and landscape changes for the past 8000 years around the site of Wakarida (Ethiopia) using chronostratigraphy

Blond¹,

Jacob-Rousseau

Bouchaud

et al. 2021

BSGF - Earth Sci. Bull.

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Geoscience is a very useful tool for approaching the relationships between societies and their environment. However, it is not always possible to apply very advanced techniques or to perform a large number of analyses. This paper aims to show that chronostratigraphic studies can provide satisfying answers to the main geoarchaeological questions, “only” using sedimentological, stratigraphic and chronological analyses. The objective here is to move from the study of stratigraphic sections, uncovered in valley bottoms filled by sedimentary deposits, to the reconstruction of landscape and environmental changes, in connection with the archaeological site of Wakarida (northern Tigray, Ethiopia). The actual landscape around Wakarida is made of steeply sloping valleys, filled with accumulations of sediments several meters thick. These deposits are cultivated by the inhabitants thanks to the building of agricultural terraces. Archaeological excavations have uncovered an urban settlement in Wakarida, dating between the classical Aksumite (150-400/450 CE) and the post-Aksumite periods (800/850 CE), and more ancient (pre- and proto-Aksumite periods) structures in the area under survey. Such structures raise the question of the interactions of the populations with their environment through time. More precisely, they question their role in the deposition of the sediments. To tackle these questions, a method based on a combination of field work, sedimentological analyses and dating has been employed. Such a chronostratigraphic study made it possible to identify several phases in the establishment of the current landscapes around the Wakarida site. During Early Holocene, valleys were gradually filled by alluvial and/or colluvial processes of low energy. During Middle Holocene, ablation processes alternated with deposition, showing the effects of climatic and possible anthropogenic processes. From the 1st millennium BCE onwards, the impact of population on their environment is visible, but especially around the 14th – 17th centuries. An important part of these conclusions is based on the attention given to chronological inversions and the fact that these dates, "false" at first glance, reveal ablation and deposition phases within sedimentary cascades. It therefore seems important, from a methodological point of view, not to reject these dates a priori, but to consider them by giving them their full place in the chronostratigraphic reflection.

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Challenges and resilience of an indigenous farming system during wartime (Tigray, North Ethiopia)

Ghebreyohannes

Nyssen

Negash

et al. 2022

Agron. Sustain. Dev.

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Due to war conditions, the local farmers had to largely rely on their own crop production, mainly by subsistence farming, in Tigray, North Ethiopia. We assessed the crop stands in 2021 and evaluated the level of resilience of the indigenous farming system. Quantitative data were collected from 161 farm parcels in various ecoregions of this tropical mountain region, in order to detect the share of sown land, crop types, and their status. This participatory monitoring was accompanied by semi-structured interviews. Farmers cultivated their farms late, left it uncultivated or marginally sowed oil crops as improved fallow (28%), due to lack of farming tools, oxen, fertilizer, seeds, or manpower. As compared to peace years, only few lands were sown with sorghum as there was active warfare in the sorghum planting period. The relatively good stands of wheat and barley (47%) are in line with the farmers’ priority given to cereals. Teff got a large land share because it could be sown up to the middle of the main rainy season and because farmers had consumed the seeds of their major cereal crops (wheat and barley) when hiding for warfare. Seeds left from consumption were only sown by late June, when troops had retreated, and the communities could revive. With almost no external support, the local farming system has proven to be remarkably resilient, relying on indigenous knowledge and local practices, block rotation, manure, improved fallow, changes in relative importance of crops, seed exchange, and support for one another. This is the first analysis of the socio-agronomic roots of the 2021–2022 Tigray hunger crisis, with a cereal harvest that could not at all sustain the local population as the planting season had been largely missed. The ability of the indigenous farming system to partially rebounce in times of autarky is another novel finding.

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Terrasses alluviales et terrasses agricoles. Première approche des comblements sédimentaires et de leurs aménagements agricoles depuis 5000 av. n. è. à Wakarida (Éthiopie)

Cited by 9 publications

References 78 publications

Understanding spatial patterns of soils for sustainable agriculture in northern Ethiopia’s tropical mountains

Understanding spatial patterns of soils for sustainable agriculture in northern Ethiopia’s tropical mountains

From section to landscape(s): reconstructions of environmental and landscape changes for the past 8000 years around the site of Wakarida (Ethiopia) using chronostratigraphy

Challenges and resilience of an indigenous farming system during wartime (Tigray, North Ethiopia)

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