Land use and climate change effects on soil erosion in a semi-arid mountainous watershed (High Atlas, Morocco)

Simonneaux, Vincent; Cheggour, A.; Deschamps, C.; Mouillot, Florent; Cerdan, Olivier; Bissonnais, Yves Le

doi:10.1016/j.jaridenv.2015.06.002

Cited by 154 publications

(81 citation statements)

References 44 publications

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“…Given the climate change scenarios that the Mediterranean regions are facing, which are marked by warming and a decrease in precipitation (Giorgi and Lionello, 2007;Montanari, 2013;Simonneaux et al, 2015), permafrost should be close to disappearing in most Mediterranean mountains. The subsurface nature of permafrost and the presence of a thawed surface layer in the warmer season (the active layer) strongly limit its identification, characterization and mapping, especially in remote mountain areas (Gruber and Haeberli, 2009).…”

Section: Introductionmentioning

confidence: 99%

New observations indicate the possible presence of permafrost in North Africa (Djebel Toubkal, High Atlas, Morocco)

2017

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Abstract. Relict and present-day periglacial features have been reported in the literature for the upper reaches of the High Atlas mountains, which is the highest range in North Africa (Djebel Toubkal -4167 m a.s.l.). A lobate feature in the Irhzer Ikhibi south at 3800 m a.s.l. has been previously interpreted as an active rock glacier, but no measurements of ground or air temperatures are known to exist for the area. In order to assess the possible presence of permafrost, we analyse data from June 2015 to June 2016 from two air temperature measurement sites at 2370 and 3210 m a.s.l. and from four ground surface temperature (GST) sites at 3220, 3815, 3980 and 4160 m a.s.l. to characterize conditions along an altitudinal gradient along the Oued Ihghyghaye valley to the summit of the Djebel Toubkal. GSTs were collected at 1 h intervals, and the presence of snow cover at the monitoring sites was validated using Landsat 8 and Sentinel-2 imagery. Two field visits allowed for logger installation and collection and for assessing the geomorphological features in the area. The results show that snow plays a major role on the thermal regime of the shallow ground, inducing important spatial variability. The lowest site at 3220 m had a thermal regime characterized by frequent freeze-thaw cycles during the cold season but with few days of snow. When snow settled, the ground surface remained isothermal at 0 • C , indicating the absence of permafrost. The highest sites at 3980 and 4160 m a.s.l. showed very frequent freeze-thaw cycles and a small influence of the snow cover on GST, reflecting the lack of snow accumulation due to the wind-exposed settings on a ridge and on the summit plateau. The site located at 3815 m in the Irhzer Ikhibi south valley had a cold, stable thermal regime with GST varying from −4.5 to −6 • C from December to March, under a continuous snow cover.The site's location in a concave setting favours wind-driven snow accumulation and lower incoming solar radiation due to the shading effect of a ridge, inducing the conservation of a thick snow pack. The stable and low GSTs are interpreted as a strong indicator of the probable presence of permafrost at this site, which is an interpretation supported by the presence of lobate and arcuate features in the talus deposits. We present first results and further observations using geophysics, and borehole measurements are foreseen. This is the first time that probable permafrost has been reported from temperature observations in the mountains of North Africa.

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Section: Introductionmentioning

confidence: 99%

New observations indicate the possible presence of permafrost in North Africa (Djebel Toubkal, High Atlas, Morocco)

2017

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“…Cela mériterait d'être examiné dans des situations variées. Il faudrait prendre en compte que ces changements pourraient potentiellement induire des impacts très importants, comme par exemple l'érosion (Simonneaux et al, 2015). Il serait pertinent d'explorer des voies de valorisation des pâtures actuelles et d'envisager d'autres ressources fourragères afin de diminuer la dépendance à l'achat de concentré.…”

Section: Discussionunclassified

Les systèmes d’élevage de petits ruminants en Tunisie Centrale : stratégies différenciées et adaptations aux transformations du territoire

et al. 2016

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Résumé -En Tunisie centrale, l'élevage ovin reste très présent, malgré les nombreuses perturbations auxquelles il fait face depuis les années 1970 : aléas climatiques, évolutions socio-économiques et culturelles, développement des cultures. Ces évolutions entraînent une diminution des ressources issues des parcours. Il s'agit de comprendre comment des familles maintiennent une activité d'élevage dans ce contexte. L'étude a été menée grâce à une enquête réalisée en 2012-2013 chez 60 éleveurs. Quatre systèmes d'élevage ont été identifiés. Trois systèmes reposent sur l'élevage de brebis et la production d'agneaux plus ou moins finis. Les « pasteurs transhumants » utilisent la mobilité à grande distance pour accéder à des parcours de végétation spontanée, gérés par l'État. Les « agriculteurs-éleveurs » utilisent le pâturage des chaumes et d'autres ressources issues des terres cultivées, ce qui leur donne une plus grande capacité d'adaptation face aux changements. Les « pluriactifs » se révèlent les plus affectés par l'occupation des terres par les cultures, au détriment des parcours dont leur élevage dépend encore. Dans ces systèmes naisseurs, une forte proportion d'éleveurs pense diminuer leurs effectifs, voire même abandonner l'activité d'élevage, face aux difficultés qu'ils rencontrent. Un quatrième système, les « négociants-engraisseurs », s'est fortement développé, fondé sur l'engraissement au grain d'agneaux achetés, sans élevage de brebis. Cette activité est rentable à court terme, mais s'avère toutefois vulnérable face aux variations des prix des compléments alimentaires.Mots clés : système / typologie / pratique / pâturage / ovins / Maghreb Abstract -Sheep breeding in Central Tunisia: varied strategies and adaptations to changes in land use. Sheep breeding in central Tunisia remains widespread, despite the many problems it had to face since the 1970s: climate hazards, socio-economic and cultural changes and the development of cropped area. These changes have led to a decrease in forage resources from rangelands. The aim of this study was to understand how families are able to maintain sheep breeding in such a context. The study involved a survey among a sample of 60 farmers in 2012-2013. We identified four types of livestock systems. Three types are based on the raising of ewes and the production of lean or fat lambs. "Transhumant pastoralists" are using long-distance mobility to access rangelands with wild vegetation, managed by the State. "Crop-Livestock" farmers use stubble for pasture, along with other resources derived from farmed land and have a greater adaptive capacity to cope with changes. Multiactive families are the most affected by the extension of crops at the expense of rangelands. For these three systems, many farmers are thinking of decreasing their number of ewes or even giving up sheep farming, due to the difficulties they face. A fourth "trader-fattener" system is strongly developing, based on fattening purchased lean lambs with grain, without raising ewes. This activity is profitable in ...

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“…Rainfall simulators are the most commonly used method (e.g., Arnau-Rosalen, Calvo-Cases, Boix-Fayos, Lavee, & Sarah, 2008;Bergkamp, Cerda, & Imeson, 1999;Dimanche & Hoogmoed, 2002;Heilweil, Mckinney, Zhdanov, & Watt, 2007;Hikel et al, 2013;Pierson et al, 2010;Seeger, 2007;Simonneaux et al, 2015;Williams, Wuest, Schillinger, & Gollany, 2006) and enable the indirect calculation of infiltration rates through the continuity equation by simultaneously measuring applied rainfall rates and observed surface runoff from a defined plot ( Figure 1a). Rainfall simulators are the most commonly used method (e.g., Arnau-Rosalen, Calvo-Cases, Boix-Fayos, Lavee, & Sarah, 2008;Bergkamp, Cerda, & Imeson, 1999;Dimanche & Hoogmoed, 2002;Heilweil, Mckinney, Zhdanov, & Watt, 2007;Hikel et al, 2013;Pierson et al, 2010;Seeger, 2007;Simonneaux et al, 2015;Williams, Wuest, Schillinger, & Gollany, 2006) and enable the indirect calculation of infiltration rates through the continuity equation by simultaneously measuring applied rainfall rates and observed surface runoff from a defined plot ( Figure 1a).…”

Section: Measuring Infiltration and Surface Runoff In Drylandsmentioning

confidence: 99%

A new approach for measuring surface hydrological connectivity

Wolstenholme

Smith

Baird

et al. 2019

Hydrological Processes

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The development of surface hydrological connectivity is a key determinant of flood magnitude in drylands. Thresholds in runoff response may be reached when isolated runoff-generating areas connect with each other to form continuous links to river channels, enabling these areas to contribute to flood hydrographs. Such threshold behaviour explains observed nonlinearities and scale dependencies of dryland rainfall-runoff relationships and complicates attempts at flood prediction. However, field methods for measuring the propensity of a surface to transmit water downslope are lacking, and conventional techniques of infiltration measurement are often inappropriate for use on non-agricultural drylands. Here, we argue for a reconceptualization of the dryland surface runoff process, suggesting that the downslope transfer of water should be considered alongside surface infiltration; that is, there is a need for the "aggregated" measurement of infiltration and overland flow hydraulics.Surface application of a set volume of water at a standardized rate generates runoff that travels downslope; the distance it travels downslope is determined by infiltration along the flow, integration of flow paths, and flow resistance. We demonstrate the potential of such a combined measurement system coupled with structure-frommotion photogrammetry to identify surface controls on runoff generation and transfer on dryland hillslopes, with vegetation, slope, surface stone cover, and surface roughness all having a significant effect. The measurement system has been used on slopes up to 37 compared with the flat surface typically required for infiltration methods. On average, the field workflow takes~10-15 min, considerably quicker than rainfall simulation. A wider variety of surfaces can be sampled with relative ease, as the method is not restricted to stone and vegetation-free land. We argue that this aggregated measurement represents surface connectivity and dryland runoff response better than standard hydrological approaches and can be applied on a much greater variety of dryland surfaces.

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Land use and climate change effects on soil erosion in a semi-arid mountainous watershed (High Atlas, Morocco)

Cited by 154 publications

References 44 publications

New observations indicate the possible presence of permafrost in North Africa (Djebel Toubkal, High Atlas, Morocco)

New observations indicate the possible presence of permafrost in North Africa (Djebel Toubkal, High Atlas, Morocco)

Les systèmes d’élevage de petits ruminants en Tunisie Centrale : stratégies différenciées et adaptations aux transformations du territoire

A new approach for measuring surface hydrological connectivity

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