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This study aims to provide a quantitative estimate of the amount of erosion caused by dust devils in the Jordan Badia, and to find the meteorological variables that drive the formation of these dust devils. To achieve this goal a field study was done in Al-Majidyya, Jordan, on 9 days in the period of July 23rd – August 5th, 2012, during which a total of 518 dust devils were observed. Dust devils were observed between 09:09 and 17:34, were most active between 12:00 and 13:00, and were significantly more active during the first than during the second part of day. Temperature lapse rates of at least 0.76 °C/m were required for dust devil formation, and dust devils became more frequent with temperature lapse rates increasing up to a value of 1.2 °C/m. Dust devil frequency remained constant with further increases in temperature lapse rate. Dust devils were observed in the wind speed range of 0.1 – 7.5 m/s, and showed a positive relation with wind speed up to a value of 2 m/s. For values of the wind speed higher than 3 m/s, the relation became negative. A cyclic pattern was observed in the lower 2.5 m of the atmosphere during which temperature lapse rate and wind speed were highly correlated and showed a cyclic pattern of rising and falling values. This cyclic pattern was proposed to negatively influence dust devil frequency. Annual amounts of erosion for the Jordan Badia were estimated at 9.79 kg/ha of locally and 0.03 kg/ha of regionally lost soil. These values were found to be low compared to other dust devil studies and other dust events. Compared to normal wind erosion, dust devils were found to be of low importance in this area. However, dust devils do contribute to atmospheric dust loading, which affects the atmospheric radiation balance, may pose health issues to humans and livestock, and may cause a loss of primary nutrients from the area. This study provides the only estimation of erosion by dust devils available for the Jordan Badia.

Tanzania’s population growth increases the stress on arable land, making it vulnerable to erosion especially in sloped areas like the Usambara Mountains. The construction of terraces and the growing of vegetative barriers are known to reduce erosion. Sustainable Land Management (SLM) measures are often modelled to evaluate its effects on runoff and erosion, but only few researches focus on the implementation of SLM types in erosion modelling. This research aims at incorporating SLM in KINEROS2 in order to develop a method to predict the effects of construction of SLM types on runoff and erosion beforehand. KINEROS2 is a distributed, event and physics based runoff and erosion model that represents the catchment by different connected and homogenous elements. For the research, 6 farmer plots in the Usambara Mountains in Tanzania were selected with the SLM types supported being terraces, agroforestry and grass trips. Input parameters required for KINEROS2 were measured in the field or determined from literature. The spatial dependency of cohesion, Ks, bulk density and soil texture on distance to trees was determined by taking measurements from a transect between two Grevillea trees. The control plots were used for calibration of the runoff and erosion parameters Ks, G, C and S. The SLM types were then incorporated in the KINEROS2 model, by representing each riser, bed and grass strip by a single element with specific parameter values depending on slope, soil type, vegetation, etc. The incorporation of SLM was validated by comparing the model results with the actual runoff and erosion data measured using Gerlach throughs. The Gerlach data did not show the expected effect of SLM on runoff. It did show a larger increase in erosion with increase in runoff on plots with poor or without SLM; the plot with grass strips showed the smallest increase in erosion. For the transect, no significant relationship of the measured parameters with tree distance was found. Therefore trees

Soil erosion is one of the world’s most serious environmental problems (Jankauskas et al, 2008). It can cause extensive losses of crop yields and cultivated and potentially productive soils (Fullen & Catt, 2004; Morgan, 1995; Skoien, 1995). Soils which are highly eroded are more easily subjected to a redundancy of productivity and are poor environments for root growth, due to a degraded structure and lower organic matter contents (Frye et al., 1982; Lindstrom et al., 1994). The mountains and highlands of East Africa are facing the problems of land degradation as well, mainly due to the human impact on the natural ecosystems (Ezaza, 1992). This is enhanced by the high population density. Also deforestation of new land even on steep slopes and over-exploitation of mountain resources, due to the high population density has led to high soil erosion rates (Ezaza, 1988). Because this area is characterized by a steep and rugged topography and most people rely on agriculture due to the fertile soils and favorable agroclimate, many farms suffer from serious soil erosion. The aim of this research was to determine the relation of soil physical properties (i.e. aggregate stability, soil texture, bulk density, porosity, infiltration rate and soil cohesion) and soil erosion rates of several hill slopes with sparse vegetation in the Lushoto district situated in the West Usambara Mountains, Tanzania. To achieve this objective the soil physical properties of four highly erosive and four less erosive soils of hill slopes has been determined to find out which of the soil physical properties are contributing most to soil erosion. These hill slopes were approximately equal in amount of vegetation and slope angle. The MMF erosion model has been used to quantify the soil erosion for each hill slope where no erosion measurements are performed. The model has been validated on six other fields for which erosion measurements are performed by Wickama (2010). Aggregate stability was significant

Sediment transport is an important component of the soil erosion process, which depends on several hydraulic parameters like unit discharge, mean flow velocity, and slope gradient. In most of the previous studies, the impact of these hydraulic parameters on transport capacity was studied for non-erodible bed conditions. Hence, this study aimed to examine the influence of unit discharge, mean flow velocity and slope gradient on sediment transport capacity for erodible beds and also to investigate the relationship between transport capacity and composite force predictors i.e. shear stress, stream power, unit stream power and effective stream power. In order to accomplish the objectives, experiments were carried out using four well sorted sands (0.230, 0.536, 0.719, 1.022 mm). Unit discharges ranging from 0.07 to 2.07 × 10-3 m2 s-1 were simulated inside the flume at four slopes (5.2, 8.7, 13.2 and 17.6 %) to analyze their impact on sediment transport rate. The sediment transport rate measured at the bottom end of the flume by taking water and sediment samples was considered equal to sediment transport capacity, because the selected flume length of 3.0 m was found sufficient to reach the transport capacity. The experimental result reveals that the slope gradient has a stronger impact on transport capacity than unit discharge and mean flow velocity due to the fact that the tangential component of gravity force increases with slope gradient. Our results show that unit stream power is an optimal composite force predictor for estimating transport capacity. Stream power and effective stream power can also be successfully related to the transport capacity, however the relations are strongly dependent on grain size. Shear stress showed poor performance, because part of shear stress is dissipated by bed irregularities, bed form evolution and sediment detachment. An empirical transport capacity equation was derived, which illustrates that transport capacity can be predicted from

The highlands in Tanzania are seriously affected by soil erosion, which leads to the formation of gullies, the collapse of soil and water conservation measures and the loss of fertile topsoil, which in turn leads to a reduction of crop yields, food deficiency, silting-up of waterways, damage to structures and loss of land value. Over the course of the past century considerable efforts have been undertaken to reduce the amount of erosion by means of soil and water conservation measures, but only minimal adoption of the promoted measures has been achieved, making soil erosion an on-going problem. The aim of this study was to locate soil and water conservation measures in the Usambara Mountains, Tanzania and to model their effectiveness. This was done by (1) assessing erosion risk in the entire Lushoto district, (2) locating soil and water conservation measures in two smaller, 10x10 km blocks near the villages of Soni and Sunga, (3) modelling the erosion in those blocks, and (4) model the effectiveness of the soil and water conservation measures. An erosion risk map of the entire district was created by using a Landsat Enhanced Thematic Mapper+ (ETM+) image and a digital elevation model created from a contour lines map with a vertical resolution of 50m. Land use maps of the 10x10 blocks were created using two standard pixel-based methods and an object-based, nearest neighbourhood method on two different scale levels. The pixel-based methods that were used were a minimum distance to means and a maximum likelihood classification method. The locations of bench terraces and grass strips were located by using object-based image analysis and the land use map with the highest accuracy, which in this case was the map created with the maximum likelihood classification method. This land use map was used to mask out areas that were not of interest. The percentage of agricultural area that contained soil and water conservation measures ranged from 2.9% to 19.75% for the Soni and S

Modern soil erosion triggered by anthropogenic forcing is a well studied phenomenon, but few studies focus on erosion on a longer timescale, forced by climatic changes. A better understanding of the way these long term climatic forcings act on soil erosion is needed to prepare ourselves for the future. Colluvial deposits form valuable archives of the past erosion on a hillslope. The West Usambara Mountains in Tanzania form an ideal location for research on the past erosion, since they are subjected to severe erosion, of which the present day part is well studied and documented. In this study, colluvial stratigraphies are interpreted and dated by OSL in order to reconstruct the geomorphic response of the landscape to past environmental changes, caused by both natural and anthropogenic forcings. The colluvial records, showing unstable periods with erosion alternated with stable periods of pedogenesis, can be linked successfully to the past climatic and anthropogenic history of the area. A reconstruction of the erosion history from the last three centuries is created, based on the information found in the colluvial deposits. This research proves that colluvium stratigraphies have a high potential for holding valuable sedimentary archives of the past erosion and environmental history. When interpreted and dated correctly, colluvial deposits can be used successfully to reconstruct the erosional history of an area.

This study was conducted within an archaeology project and was done to provide some insights to the relation between artefact distribution/ origin and geomorphological development during the late Pleistocene and Holocene. Geological, lithological and geomorphological research showed several distinguishable landscape units. In the western part of the study area a swamp is present that used to be a lake, which can be seen as a favorable location for ancient human settlement. Besides this geomorphology focused research, also archaeological surveys have been done around this swamp and at some main locations of interest north of the swamp (e.g. Kamaroti hill). This study concluded that the artefact distribution along Kamaroti hill can be related with a former marine environment that was implicated by lithological research. However, the headward erosion of the walls of the highly abundant agricultural terraces in the study area caused exposure of artefacts through time. This is one of the reasons for the archaeologically complexity of the scattering of artefact distribution. Thick accumulations of terra rossa between a relative isolated region between the mountains in the western part of the study area were related with ancient soil erosion on the mountain slopes and the subsequent colluvial transport to these sediment catches.

Erosion/deposition was investigated on an archaeologically rich hill (Kamaroti) in southern Zakynthos, Greece. It was believed that the distribution pattern of archaeological artefacts was linked to erosion and deposition in the research area. Investigation took place by usage of a modified version of the Morgan-Morgan-Finney erosion model (MMF-model) to quantify erosion rates and look at the spatial distribution of erosion/deposition. The model was applied in a GIS-environment. Two DEM’s were used, one based on interpolation of digitized 4m elevation lines, and a very detailed DEM based on differential GPS measurements. Model results show that erosion/deposition on Kamaroti is fairly limited. This is in concurrence with results from similar types of studies on erosion/deposition in terraced olive orchards. While particle detachment by rain drop is relatively high due to the intense rainfall regime, transport capacity of the generated runoff was estimated low due the terraced layout and crop management on the hill. Artefacts are uncovered on the surface, but transportation is limited. Probably soil erosion has been limited throughout history in the entire research area. The only area were intense erosion has been taking place is probably related to human settlement in historical times.