Preventing the off‐site effects of soil erosion is an essential part of good catchment management. Most efforts are in the form of on‐site soil and water conservation measures. However, sediment trapping can be an alternative (additional) measure to prevent the negative off‐site effects of soil erosion. Therefore, not all efforts should focus solely on on‐site soil conservation but also on the safe routing of sediment‐laden flows and on creating sites and conditions where sediment can be trapped. Sediment trapping can be applied on‐site and off‐site and involves both vegetative and structural measures. This paper provides an extensive review of scientific journal articles, case studies and other reports that have assessed soil conservation efforts and the sediment trapping efficacy (STE) of vegetative and structural measures. The review is further illustrated through participatory field observation and stakeholders' interview. Vegetation type and integration of two or more measures are important factors influencing STE. In this review, the STE of most measures was evaluated either individually or in such combinations. In real landscape situations, it is not only important to select the most efficient erosion control measures but also to determine their optimum location in the catchment. Hence, there is a need for research that shows a more integrated determination of STE at catchment scale. If integrated measures are implemented at the most appropriate spatial locations within a catchment where they can disconnect landscape units from each other, they will decrease runoff velocity and sediment transport and, subsequently, reduce downstream flooding and sedimentation problems. Copyright © 2014 John Wiley & Sons, Ltd.
Anastomosing river plains of the Channel Country, central Australia, have aggraded slowly over the past 100 ka. Channel sediments accumulate mainly as accretionary benches of mud and sand, sandy channel‐base sheets and vegetation‐shadow deposits. The channels are laterally stable and the sediments have aggraded locally against erosional banks of tough floodplain muds. Channel sediments are profoundly affected by desiccation during dry periods and by bioturbation caused by within‐channel trees and burrowing invertebrates, especially crayfish. Excavations show that mud‐dominated channel bodies of low width:thickness ratio are generated by a combination of vertical and lateral accretion. Levees and braided surfaces, composed mainly of mud aggregates, border the channels and are activated during valley‐wide floods which lay down distal mud sheets. Floodplain muds are converted to vertisols with gilgai, deep desiccation cracks, and impregnations of carbonate and gypsum. A fixed‐channel facies model is applicable to the Channel Country river deposits. Anastomosis apparently results from the need for the system to move large volumes of water and moderate sediment loads across low‐gradient interior basins. Channels distant from upland source areas receive an abundant supply of pedogenic, sand‐sized mud aggregates generated on adjacent floodplains and reworked into braid bars during valley‐wide floods. Some quartz sand is provided from excavation of subsurface Pleistocene sands in deep channels and waterholes and from aeolian dunes on the floodplains. Adjacent gibber plains supply some gravel to the system.
Abstract:As a low-gradient arid region spanning the tropics to the temperate zone, the Lake Eyre basin has undergone gentle late Cenozoic crustal warping leading to substantial alluvial deposition, thereby forming repositories of evidence for palaeoclimatic and palaeohydrological changes from the Late Tertiary to the Holocene. Auger holes and bank exposures at five locations along the lower 500 km of Cooper Creek, a major contributor to Lake Eyre in the eastern part of the basin, yielded 85 luminescence dates (TL and OSL) that, combined wit a further 142 luminescence dates from northeastern Australia, have established a chronology of multiple episodes of enhanced flow regime from about 750 ka to the Holocene. Mean bankfull discharges on Cooper Creek upstream of the Innamincka Dome at 250-230 ka or oxygen isotope stages (OIS) 7-6 are estimated to have been 5 to 7 times larger than those of today, however, substantially less reworking has occurred during and after OIS 5 than before. Lower Cooper Creek appears to have similarly declined. In the Tirari Desert adjacent to Lake Eyre there is evidence of widespread alluvial activity, perhaps during but certainly before the Middle Pleistocene, yet the river became laterally restricted in OIS 7 to 5. While the Quaternary has been characterised by a dramatically oscillating wet-dry climate, since oxygen isotope stage OIS 7 or 6 there has been a general decline in the magnitude of the episodes of wetness to which the eastern part of central Australia has periodically returned. During the last full glacial cycle, Cooper Creek's periods of greatest runoff and sand transport were not during the last interglacial maximum of OIS 5e (132-122 ka) but later in OIS 5 when sea levels and global temperatures were substantially below those of 5e or today. Fluvial activity returned in OIS 4 and 3, but not to the extent of mid and late OIS 5; strongly seasonal but still powerful flows transported sand and fed source-bordering dunes in OIS 5 and 3. This chronology of fluvial activity in the late Quaternary broadly coincides with that for rivers of southeastern Australia and suggests that the wet phases in eastern central Australia have not been governed as much by the northern monsoon as by conditions in the western Pacific close to the east coast both north and south. Flow confinement within the Innamincka Dome has locally amplified Cooper Creek's energy, and here evidence exists for short but high-magnitude episodes of flow during the Last Glacial Maximum and in the early to middle Holocene, conditions that were capable of forming large palaeochannels but that were not long-lived enough to rework the river's extensive floodplains elsewhere along its length.
Depending on the amount of aeolian sediment input and dune erosion, dune size and morphology change over time. Since coastal foredunes play an important role in the Dutch coastal defence, it is important to have good insight in the main factors that control these changes. In this paper the temporal variations in foredune erosion and accretion were studied in relation to proxies for aeolian transport potential and storminess using yearly elevation measurements from 1965 to 2012 for six sections of the Dutch coast. Longshore differences in the relative impacts of erosion and accretion were examined in relation to local beach width. The results show that temporal variability in foredune accretion and erosion is highest in narrow beach sections. Here, dune erosion alternates with accretion, with variability displaying strong correlations with yearly values of storminess (maximum sea levels). In wider beach sections, dune erosion is less frequent, with lower temporal variability and stronger correlations with time series of transport potential. In erosion dominated years, eroded volumes decrease from narrow to wider beaches. When accretion dominates, dune-volume changes are relatively constant alongshore. Dune erosion is therefore suggested to control spatial variability in dune-volume changes. On a scale of decades, the volume of foredunes tends to increase more on wider beaches. However, where widths exceed 200 to 300 m, this trend is no longer observed.
ABSTRACT. Mediterranean forests are frequently subject to wildfires, inducing risks of high runoff and loss of nutrient-rich topsoil. The mechanisms influencing investigamos los efectos post-incendio de un fuego de laboratorio y dos experimentos sucesivos de lluvia simulada para evaluar las consecuencias a corto plazo de un incendio sobre los parámetros hidrológicos y la erodibilidad del suelo, examinando (i) los niveles de repelencia al agua y su distribución, (ii) los rasgos de la cubierta superficial, y (iii) las respuestas de la infiltración, la escorrentía y la erosión frente a la lluvia simulada en una situación no perturbada (con suelo desnudo y cubierto de acículas) y quemada (con y sin cenizas). La repelencia al fuego
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