Uranium comminution age responds to erosion rate semiquantitatively

Here we present(^(234)U/^(238)U)data from river sediments collected on the Tibetan Plateau.The(^(234)U/^(238)U)ratios of a specific grain size fraction show good correlation with erosion rates,which were determined by in-situ–produced cosmogenic nuclides.This correlation has previously been observed in a wide range of geomorphic settings,suggesting that(^(234)U/^(238)U)ratios of fluvial sediments have great potential to quantify erosion rates.

Spatial distribution of soil hydraulic parameters estimated by pedotransfer functions for the Jialing River Catchment,Southwestern China

Soil hydraulic parameters θs,α,n,Ks,L and θr of the van Genuchten-Mualem model were estimated using three pedotransfer functions(PTFs) based on soil properties for surface soils of the largest main tributary catchment(the Jialing River) of the upper Yangtze River in China.The soil database was from the second national soil survey of China with a spatial 30 × 30 arc-second resolution.According to the statistical analysis of the differences between the continuous-PTFs-estimated values of soil hydraulic parameters for the study catchment and the reference values for a specific texture class provided in the development database of a specific PTF,best estimations were obtained using the W?sten PTF.The Rawls & Brakenssiek PTF was good estimation for parameter θr that was assumed as zero by W?sten PTF.The established higher θr(0.08%) and lower Ks(20 cm/d) and θs(0.43%) in the mid-downstream area relative to the other areas of the catchment could lead to larger amounts of surface runoff andconsequently provide higher energy to erode soil.Thus,these factors provide a supporting explanation for previously reported severe soil erosion occurring in this area.Spatial heterogeneity analysis for estimated hydraulic parameters in terms of semivariogram showed that the spatial correlation distance was in the range of 50-80 km and that the spatial variability(sill) was not large except for parameters Ks and L.The semi-variance with the exponential model at the zero distance(nugget) was 30%-50% of the sill.This study provided a practical PTF approach for estimating soil hydraulic properties from soil survey data at a large watershed scale.The estimation results could provide better insight into the mechanism of surface runoff and soil erosion,which is important to better understand and manage erosion in the catchment.

Evaluation of the post-fire erosion and flood control works in the area of Cassandra(Chalkidiki, North Greece)

We quantified morphological and hydrographical characteristics of two drainage basins（Chanioti and N. Skioni） on Cassandra peninsula of Chalkidiki（North Greece）, and evaluated the effectiveness of post-fire flood and erosion control works. The drainage basins were chosen because of their severe damage by fire, post-fire potential for erosion and flood due to the steep relief, and the importance of the area for residential and tourism development. The first measures taken in the area after the fire were salvage cutting of burned trees, a total ban on grazing, and construction of three types of works, log erosion barriers（LEBs）, log check dams and contour branch barriers. Almost all necessary post-fire works were completed in both catchments but many construction failures were recorded. Approximately 75 % of the LEBs and45 % of the contour branch barriers functioned properly,while the remainder failed. Nearly 80 % of the log dams were sedimented to 0–20 % of the dam height, 14.3 %were 20–40 % filled and 5.9 % collapsed. Despite these failures, peak discharge declined by 10.5 % in Chanioti and 20.4 % in N. Skioni catchment. The main reasons for works failures were the rush of construction and the limited supervision of workers, which resulted in floods during the years that followed.

MINErosion 4:Using measurements from a tilting flume-rainfall simulator facility to predict erosion rates from post-mining catchments/landscapes in Central Queensland,Australia

The use of draglines to remove overburden in Queensland opencut mines,results in landscapes that consist of long parallel tertiary overburden spoil-piles that are generally highly saline,dispersive,and highly erodible.The height of these spoil-piles may exceed 50-60 m above the original landscapes and the slopes are at the angle of repose of around 75%or 37°.Legislation and public opinion require that these highly disturbed open-cut post-mining landscapes should be satisfactorily rehabilitated into an approved post-mining land use with acceptable erosion rates.Therefore,these slopes must be reduced before the landscape can be rehabilitated.The most expensive component of the rehabilitation process is the re-shaping and preparation of the overburden to create a suitable landscape for vegetation growth.As soils and overburden varies greatly in their erodibilities,the extent and cost of earthworks can be minimized,and rehabilitation failures avoided,if soil erosion from designed landscapes can be predicted using laboratory-based parameters prior to construction of these landscapes.This paper describes the development of a model for that purpose.A catchment or landscape erosion model MINErosion 4 was developed by upscaling the existing hillslope model MINErosion 3(So,et al.,2018)and integrate it with both ESRI ArcGIS 10.3 or QGIS 3.16(freeware),to predict event based and mean annual erosion rate from a postmining catchment or landscape.MINErosion 3 is a model that can be used to predict event and annual erosion rates from field scale hillslopes using laboratory measured erodibility parameters or routinely measured soil physical and chemical properties,and to derive suitable landscape design parameters(slope gradient,slope length and vegetation cover)that will result in acceptable erosion rates.But it cannot be used to predict the sediment delivery from catchments or landscapes.MINErosion 4 was validated against data collected on three instrumented catchments(up to 0.91 ha in size)on the Curragh mine site in Central Queensland.The agreement between predicted(Y)and measured(x)values were very good with the regression equation of Y-0.92X and an R^(2) value of 0.81 for individual storm events,and Y-1.47X and an R^(2) value of 0.73 for the average annual soil loss.This is probably the first time that a catchment scale erosion is successfully predicted from laboratory measured erodibility parameters.