Wind Erosion

E STIMATING equations were developed for the mean velocity profile parameters (Zo, u,o, and D) in the logarithmic law and for longitudinal turbulence intensity (uU/ZZ). The estimates were based on wind tunnel measurements over several, roughness element shapes, sizes, heights, and geo- metrical patterns. All the prediction equations had correlation coefficients > 0.90. These equations have application in wind erosion

The Australian continent is characterised by an extremely variable surficial geochemistry, reflecting the varied lithology of Australian basement rocks. Samples representative of Australian aeolian dust have been collected in (1) regions where meteorological records, satellite observation and wind erosion modelling systems have indicated frequent dust activity today (mainly the Lake Eyre Basin), and (2) from deposits of mixed dust materials. The 87Sr/86Sr and 143Nd/144Nd isotopic composition of the fine (< 5 μm) fraction of Australian dust samples was measured for comparison with the Sr and Nd isotopic composition of fine aeolian dust that reached the interior of the East Antarctic Plateau. The isotopic field for Australian dust is characterised by 87Sr/86Sr ratios ranging from 0.709 to 0.732 and εNd(0) between − 3 and − 15. The low Sr radiogenic values and εNd(0) of − 3 obtained for Lake Eyre samples are explained by the lithology of the Lake Eyre catchment showing a dominance o...

We have conducted a long-term (from 1956 to 1999) rehabilitation experiment on mobile sand dunes in Tengger Desert, China, to investigate the chronological development of microbiotic soil crusts. We systematically analyzed the progression and development of the soil crusts by investigating the plant cover (herbs and shrubs), and some microorganism (mosses and algae), physical (particle size, saturated hydraulic conductivity and saturated water content) and chemical (major plant nutrients and organic matter) soil particles. The Limburg Soil Erosion Model was used to simulate infiltration and runoff. Three stages of microbiotic crust development occurred during the progressive stabilization of unconsolidated aeolian dunes, from 1956 to the present day: (1) raindrop impact and development of a non-biological crust; (2) crust enriched with mosses; (3) crust dominated by abundant algae, mosses and liverworts. It is considered that the most significant driving factor in the ecological development of microbiotic crusts in the Tengger Desert is the spatial variability of rainfall infiltration depth within the various soil layers occurring on, for example, dune top, leeward slopes, inter-dune depression (hollow) and windward slopes, immediately after a single individual rainfall event. Crust development leads to a change from shrubs to herbs because of decreased soil moisture in deeper soil layers.

En Bolivia cerca del 40% de las tierras están afectadas por procesos de erosión asociados a factores como el agua, viento y manejo inadecuado de los suelos. Actualmente, la quinua es un cultivo que tiene demanda internacional incidiendo en la habilitación de nuevas tierras para su producción. La zona productora de quinua en el altiplano sur de Bolivia, se caracteriza por presentar un clima árido con fuertes vientos que influyen el arrastre de partículas con el consiguiente efecto sobre la disponibilidad de nutrientes en el suelo. El objetivo del presente trabajo es cuantificar la cantidad de suelo erosionado por la acción de viento mediante la utilización de un colector Big Spring Number Eight (BSNE) desarrollado por Fryrear (1986). Este instrumento presenta tres colectores ubicados a 10 cm, 50 cm y 150 cm de altura desde la superficie del suelo. Se utilizaron tres colectores en un extremo y tres colectores en el otro de cada parcela, la distancia entre colectores fue de 10 metros, de esta manera el área de influencia de cada parcela fue de 4000 m2. Fueron identificados tres unidades de manejo a saber: parcela en descanso (barbecho), parcela de quinua abonada con estiércol de ganado camélido y parcela de quinua sin abonar. Para el suelo recogido en los colectores, se determinó el peso de suelo acumulado, nitrógeno total y materia orgánica. Los resultados muestran que existe un mayor movimiento de partículas en los primeros 10 cm del suelo esto

Many rivers in Nepal are either ungauged or poorly gauged due to extreme complex terrains, monsoon climate and lack of technical and financial supports. In this context the role of hydrological model is extremely useful. In practical applications, hydrological models are relatively simple to implement and reasonably accurate. The present study concerns about simulating the flow of the Marshyangdi river basin and validate with the gauge station within the studied basin area. Furthermore, estimation and analysis of discharges for each subbasins of Marshyangdi river basin has be performed in this study. The HEC-HMS 4.3 hydrologic model (Developed by US Hydrologic Engineering Center was used to calibrate (from 2003-2007) and validate (from 2008-2012) the Marshyangdi river basin. The main data required as input includes rainfall, DEM (digital elevation model) soil, land use and metrological for model. After having data, HEC-HMS model are operated. The main output from model is discharge ...

While it needs yet to be assessed whether or not wind erosion in Western Saxony is a major point of concern regarding land degradation and fertility, it has already been recognized that considerable off-site effects of wind erosion in the adjacent regions of Saxony-Anhalt and Bran-denburg are connected to the spread of herbicides, pesticides and dust. So far, no wind erosion assessment for Western Saxony, Germany, exists. The wind erosion model previously applied for Germany (DIN standard 19706) is considering neither changes in wind direction over time nor influences of field size. This study aims to provide a first assessment of wind erosion for Western Saxony by extending the existing DIN model to a multidirectional model on soil loss by wind (SoLoWind) with new controlling factors (changing wind directions, soil cover, mean field length and mean protection zone) combined by fuzzy logic. SoLoWind is used for a local off-site effect evaluation in combination with high-resolution wind speed and wind direction data at a section of the highway A72. The model attributes 3·6% of the arable fields in Western Saxony to the very-high-wind erosion risk class. A relationship between larger fields (greater than 116 ha) and higher proportions (51·7%) of very-high-wind erosion risk can be observed. Sections of the highway A72 might be under high risk according to the modelled off-site effects of wind erosion. The presented applications showed the potential of SoLoWind to support and consult management for protection measures on a regional scale.

En Algérie, près de 20 millions d'hectares sont menacés par l'érosion éolienne. Depuis longtemps, le phénomène de l'érosion éolienne et ses effets néfastes sur le milieu naturel et l'environnement, constituent un sérieux problème, surtout dans les zones arides du pays. Ces dernières années, suite à l'exploitation irrationnelle des ressources naturelles (fourragères) et à la mise en culture des terres fragiles (défrichement) ce processus s'est particulièrement accentué. L'ampleur de la dégradation dans la zone aride de la wilaya de Naâma a engendré une situation nouvelle caractérisée par la réduction du couvert végétal, la diminution de la production ainsi que l'extension de l'ensablement rapide sur les zones mises en valeur. A travers cette étude, nous avons essayé de montrer d'une part, le potentiel de l'utilisation de la télédétection et du système d'information géographique pour la caractérisation de l'état de l'occupation d...

The Fayum is a depression below sea level, formed by wind erosion 1.8 million years ago, covering ca 12,000 km2. It consists of two lacustrine complexes, Birket Qarun and the two artificial Wadi el-Rayan lakes. Lake Qarun is a saline remnant of the historical freshwater Lake Moeris. It used to be supplied by Nile water between its formation (about 1980 bc) and the Ptolemaic period (323–246 bc). The lake is no longer connected to the Nile and needs to be supplied with pumped water that evaporates in its basin. Consequently, the lake showed a strong increase in salinity, especially during the twentieth century. It evolved from a brackish to a hypersaline state, with incisive repercussions on all biota. In Wadi el-Rayan area, two successive lakes, separated by a waterfall, were created as a reservoir for drainage wastewater. These lakes currently exceed the capacity of Lake Qarun. The physical and chemical variables, phytoplankton, zooplankton, macrobenthos and fish of the two lake complexes are discussed. Among other things, it is argued that the rapid change in salinity of Lake Qarun excludes the presence of endemic species in its fauna.

Most countries in Central America and the Caribbean depend heavily on agri-culture; efforts to sustain and improve the sector's productivity are therefore cru-cial to the region's economic development and to the welfare of its people. Land degradation is thought to pose a severe threat to the sustainability of agricultural production. Yet despite long-standing concern about this threat and dramatic claims of environmental damage, surprisingly little empirical analysis has been done on the causes and severity of land degradation problems in the region and on how best to tackle them. Meanwhile, many of the conservation programs de-signed to address the problems have fallen short of expectations. Often farmers have not adopted the recommended conservation practices or have abandoned them once the project ended. The research presented in this article attempts to bridge the empirical gap, us-ing cost-benefit analysis to investigate the nature and severity of the soil degra-dati...

This paper explores historical evolution of blowouts at Cape Cod National Seashore (CCNS), USA — a site that
hosts one of the world's highest densities of active and stabilized blowouts. The Spatial–Temporal Analysis of
Moving Polygons (STAMP) method is applied to a multi-decadal dataset of aerial photography and LiDAR to
extract patterns of two-dimensional movement andmorphometric changes in erosional deflation basins and depositional
lobes. Blowout development in CCNS is characterized by several geometric (overlap) and movement
(proximity) responses, including: i) generation and disappearance, ii) extension and contraction, iii) union or
division, iv) clustering and v) divergence by stabilization. Other possible movement events include migration,
amalgamation and proximal stabilization, but they were not observed in this study. Generation events were
more frequent than disappearance events; the former were highest between 1985 and 1994, while the latter
were highest between 2000 and 2005. High rates of areal change in erosional basins occurred between 1998
and 2000 (+3932 m2 a−1), the lowest rate (+333 m2 a−1) between 2005 and 2009, and the maximum rate
(+4589 m2 a−1) between 2009 and 2011. Union events occurred mostly in recent years (2000–2012), while
only one division was observed earlier (1985–1994). Net areal changes of lobes showed gradual growth from a
period of contraction (−1119 m2 a−1) between 1998 and 2000 to rapid extension (+2030 m2 a−1) by 2010,
which is roughly concurrent with rapid growth of erosional basins between 2005 and 2009. Blowouts extended
radially in this multi-modal wind regime and, despite odd shapes initially, they became simpler in form (more
circular) and larger over time. Net extension of erosional basins was toward ESE (109°) while depositional
lobes extended SSE (147°). Lobes were aligned with the strongest (winter) sand drift vector although their
magnitude of areal extension was only 33% that of the basins. These differences in extension responses likely
result from more complex and evolving flow-form interactions inside erosional basins. Historical photographs
and CCNS documents suggest that blowout evolution may be influenced by land-use changes, such as revegetation
campaigns in 1985 that were followed by high blowout generation. High magnitude regional storm events
(e.g., hurricanes) also play a role. The analytical framework presented provides a systematic means for twodimensional
geomorphic change detection and pattern analysis that can be applied to other landscapes.

Wind erosion susceptibility of the Hungarian soils was mapped on national level integrating three pillars of the complex phenomenon of deflation. Results of wind tunnel experiments on erodibility of various and representative soil samples were used for the parametrization of countrywide map of soil texture compiled for the upper 5 centimeter layer of soil, which resulted in a map representing threshold wind velocity exceedance. Average wind velocity was spatially estimated with 0.5' resolution using the MISH method elaborated for the spatial interpolation of surface meteorological elements. The ratio of threshold wind velocity exceedance was determined based on values predicted by the soil texture map at the grid locations. Ratio values were further interpolated to a finer 1 ha resolution using sand and silt content of the uppermost (0–5 cm) soil as spatial co-variables. Land cover was also taken into account excluding areas which are not relevant from the aspect of wind erosion (forests, water bodies, settlements etc.) to spatially assess the risk of wind erosion. According to the resulted map of wind erosion susceptibility, about 10 % of the total area of Hungary can be identified as susceptible for wind erosion. The map gives more detailed insight into the spatial distribution of wind-affected areas in Hungary as opposed to former works.

Wind erosion is an important soil degradation process in the semi-arid Pampas of Argentina, but no attempts have been made to predict the process in this region. One limitation for the use of event-based wind erosion prediction models is the lack of reliable climatic data to initiate these models. As an effort to apply wind erosion models, we compared field wind erosion measurements carried out during 4 years in a bare soil reference plot (RP) and during 3 years in the same soil with different tillage conditions: conventional (CT) and no-till (NT). Wind erosion was predicted with: (1) subroutines for single storm event versions of the wind erosion prediction system (WEPS) and the revised wind erosion equation (RWEQ), for which the climatic data of each single storm were used, and (2) the wind erosion equation (WEQ) for full rotation periods, for which long-term climatic records (1961–2004) were used. Wind erosion field measurements were carried out with BSNE samplers in 1-ha plots. Regression of predicted soil erosion rates from WEPS (y = 0·5192x + 0·0589, R2 = 0·89) and RWEQ (y = 0·5691x − 7·071, R2 = 0·90) predictions with field measurements of soil erosion rates obtained in RP (54·51 kg m−1 on average) were highly significant, but both models underestimated wind erosion by 40–45 per cent. Predictions of wind erosion made with RWEQ were highly sensitive to variations in the soil crusting factor (SCF), varying from 60·5 t m−1 when predictions for a single storm were made using the SCF default data to 0·699 t m−1 when SCF was deduced from visual field observations. The WEQ predictions agreed adequately with measured erosion for 16 rotation periods either when using a climatic C factor value of 92, corresponding to the 1961–2004 period (y = 0·9422x − 1·9248, R2 = 0·96) or a C factor value of 80, corresponding to the moister 1985–2004 period (y = 0·7612x − 1·5543, R2 = 0·96). Neither WEPS nor RWEQ predicted the low amounts measured in CT and NT (3·86 kg m−1 on average) for storms lasting approximately 24 hours. High plant or residue soil coverage as well as high oriented surface roughness eliminated erosion according to WEPS and RWEQ. These results indicated that WEQ can be used as a reliable prediction model for long-term predictions of wind erosion in the semi-arid Pampas, even when run with limited available climatic data for this region. Copyright © 2008 John Wiley & Sons, Ltd.