Due to specific environmental conditions, headwater catchments located on volcanic slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring ...Due to specific environmental conditions, headwater catchments located on volcanic slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring causes that the governing processes and patterns in these areas are rarely well understood. In this study, spatiotemporal water discharge and sediment transport from upstream sources was investigated in one of the numerous headwater catchments located in the lahar valleys of the Kamchatka Peninsula Sukhaya Elizovskaya River near Avachinskii and Koryakskii volcanoes. Three different subcatchments and corresponding channel types （wandering rivers within lahar valleys, mountain rivers within volcanic slopes and rivers within submountain terrains） were identified in the studied area. Our measure- ments from different periods of observations between years 2012-2014 showed that the studied catchment was characterized by extreme diurnal fluctuation of water discharges and sediment loads that were influenced by snowmelt patterns and high infiltration rates of the easily erodible lahar deposits. The highest recorded sediment loads were up to 9-104 mg/L which was related to an increase of two orders of magnitude within a one day of observations. Additionally, to get a quantitative estimate of the spatial distribution of the eroded material in the volcanic substrates we applied an empirical soil erosion and sediment yield model - modified universal soil loss equation （MUSLE）. The modeling results showed that even if the applications of the universal erosion model to different non-agricultural areas （e.g., volcanic catchments） can lead to irrelevant results, the MUSLE model delivered might be acceptable for non-lahar areas of the studied volcanic catchment. Overall the results of our studyincrease our understanding of the hydrology and asso- ciated sediment transport for prediction of risk manage- ment within headwater volcanic catchments.展开更多
In order to determine a rational protocol for isotonic training from macroscopic angle, five training protocols were designed, particularly protocols composed of pure eccentric contraction with heavy resistance in dif...In order to determine a rational protocol for isotonic training from macroscopic angle, five training protocols were designed, particularly protocols composed of pure eccentric contraction with heavy resistance in different propotions. The study results indicated that the protocol mixed with faster speed eccentric training,being more rational than traditional isotonic training and pure isotonic eccentric training, had the most all - round effects(including change of musle size, isotonic strength, musle power and et al. ). The protocol principle mixed with faster speed eccentric training may be widely used in rehabilitation and sports training,especially in the sports events of strength resistance. The significance to study the ratio of eccentric contaction to concentic contraction was suggested.展开更多
Water erosion is a natural fact in the cycle of shaping the earth’s landforms and the most evident form of land degradation on a planetary scale </span></span><a href="#R20"><span style...Water erosion is a natural fact in the cycle of shaping the earth’s landforms and the most evident form of land degradation on a planetary scale </span></span><a href="#R20"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">(Roose & De Noni, 2004;</span></span></span><span><span></span></span></a><span><span><span style="font-family:"color:#538135;"> </span></span></span><a href="#R08"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Dautrebande & Sohier, 2006;</span></span></span><span><span></span></span></a><span><span><span style="font-family:"color:#538135;"> </span></span></span><a href="#R25"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Toumi et al., 2013;</span></span></span><span><span></span></span></a><span><span><span style="font-family:"color:#538135;"> </span></span></span><a href="#R03"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Azaiez, 2020a)</span></span></span><span><span></span></span></a><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">. Its effects have largely affected the rural landscape. Although it is the result of an ancient and primeval climatic and tectonic forcing, man’s footprint in its intensification remains a reality. A real awareness of this problem on the part of scientists is reflected in the many studies on understanding the risks. Experiments have been carried out, equations and models have been developed with the aim of preserving the soil. The watershed of wadi El Badalah, the subject of this study, is not excluded from this risk. The present research is a new comparative contribution to the quantification of soil loss based on four empirical models (Universal Soil Loss Equation USLE, Revised Universal Soil Loss Equation RUSLE, Modified Universal Soil Loss Equation MUSLE and the adjuste展开更多
The proposed site for the construction of a new dam(Laleni Dam)on the Tsitsa River in the Eastern Cape,South Africa falls within a high soil erosion zone,which is expected to affect the lifespan of the dam.Estimating ...The proposed site for the construction of a new dam(Laleni Dam)on the Tsitsa River in the Eastern Cape,South Africa falls within a high soil erosion zone,which is expected to affect the lifespan of the dam.Estimating the sediment yield of the catchment is important from a management perspective,and thus we designed this study to assess the applicability of the Modified Universal Soil Loss Equation(MUSLE).The original MUSLE was applied to the Inxu River sub catchment,upstream of a proposed dam,over a summer rainfall period extending from October 2016 to April 2017.A modified version of the MUSLE,incorporating a storage module,was later applied over the same period.Model calibration of the MUSLE with and without a storage model was tested against 7 months of recorded daily suspended sediment discharge data.With a storage model,we achieved a percentage bias,coefficient of efficiency and R2 of 2%,0.83 and 0.83,respectively,while without storage the performance statistics were markedly lower.These results suggest that a calibrated MUSLE can provide estimates of sediment yield that are valuable for regional planning,and that the inclusion of a storage component further improves the MUSLE application.Given the complexity of sediment generation and transport processes,a relatively simple empirical MUSLE model is a useful tool for initial sediment yield estimation for planning purposes.展开更多
文摘Due to specific environmental conditions, headwater catchments located on volcanic slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring causes that the governing processes and patterns in these areas are rarely well understood. In this study, spatiotemporal water discharge and sediment transport from upstream sources was investigated in one of the numerous headwater catchments located in the lahar valleys of the Kamchatka Peninsula Sukhaya Elizovskaya River near Avachinskii and Koryakskii volcanoes. Three different subcatchments and corresponding channel types （wandering rivers within lahar valleys, mountain rivers within volcanic slopes and rivers within submountain terrains） were identified in the studied area. Our measure- ments from different periods of observations between years 2012-2014 showed that the studied catchment was characterized by extreme diurnal fluctuation of water discharges and sediment loads that were influenced by snowmelt patterns and high infiltration rates of the easily erodible lahar deposits. The highest recorded sediment loads were up to 9-104 mg/L which was related to an increase of two orders of magnitude within a one day of observations. Additionally, to get a quantitative estimate of the spatial distribution of the eroded material in the volcanic substrates we applied an empirical soil erosion and sediment yield model - modified universal soil loss equation （MUSLE）. The modeling results showed that even if the applications of the universal erosion model to different non-agricultural areas （e.g., volcanic catchments） can lead to irrelevant results, the MUSLE model delivered might be acceptable for non-lahar areas of the studied volcanic catchment. Overall the results of our studyincrease our understanding of the hydrology and asso- ciated sediment transport for prediction of risk manage- ment within headwater volcanic catchments.
文摘In order to determine a rational protocol for isotonic training from macroscopic angle, five training protocols were designed, particularly protocols composed of pure eccentric contraction with heavy resistance in different propotions. The study results indicated that the protocol mixed with faster speed eccentric training,being more rational than traditional isotonic training and pure isotonic eccentric training, had the most all - round effects(including change of musle size, isotonic strength, musle power and et al. ). The protocol principle mixed with faster speed eccentric training may be widely used in rehabilitation and sports training,especially in the sports events of strength resistance. The significance to study the ratio of eccentric contaction to concentic contraction was suggested.
文摘Water erosion is a natural fact in the cycle of shaping the earth’s landforms and the most evident form of land degradation on a planetary scale </span></span><a href="#R20"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">(Roose & De Noni, 2004;</span></span></span><span><span></span></span></a><span><span><span style="font-family:"color:#538135;"> </span></span></span><a href="#R08"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Dautrebande & Sohier, 2006;</span></span></span><span><span></span></span></a><span><span><span style="font-family:"color:#538135;"> </span></span></span><a href="#R25"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Toumi et al., 2013;</span></span></span><span><span></span></span></a><span><span><span style="font-family:"color:#538135;"> </span></span></span><a href="#R03"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Azaiez, 2020a)</span></span></span><span><span></span></span></a><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">. Its effects have largely affected the rural landscape. Although it is the result of an ancient and primeval climatic and tectonic forcing, man’s footprint in its intensification remains a reality. A real awareness of this problem on the part of scientists is reflected in the many studies on understanding the risks. Experiments have been carried out, equations and models have been developed with the aim of preserving the soil. The watershed of wadi El Badalah, the subject of this study, is not excluded from this risk. The present research is a new comparative contribution to the quantification of soil loss based on four empirical models (Universal Soil Loss Equation USLE, Revised Universal Soil Loss Equation RUSLE, Modified Universal Soil Loss Equation MUSLE and the adjuste
文摘西南山区山洪灾害防治通常按照“暴雨-洪水-水位-淹没”的思路,主要关注“水”的影响,而忽视“泥沙”的作用。受洪水含沙量的影响,这些地区小水大灾时有发生。本研究以川西南典型山区河流寿溪河为例,基于HEC-HMS(The Hydrologic Engineering Center’s Hydrologic Modeling System)模型在进行场次洪水预报的基础上,利用SPSS(Statistical Product and Service Solutions)软件分析降雨强度、下垫面情况、地形因子以及土壤粒径4种因素与流域产沙量的相关性。研究结果表明,对流域产沙影响最大的因素为土壤侵蚀因子,达到0.261;影响最小的为降雨强度,仅为0.073。为进一步估算场次洪水产沙量,简化了HECHMS模型中的MUSLE(Modified Universal Soil Loss Equation)公式,按主成分综合模型中各影响因素的综合权重进行分类,重新定义了流域场次洪水产沙的估算公式。研究结果对估算山区中小流域场次洪水产沙量有参考价值。
基金supported by the Water Research Commission of South Africa under project K5/2448,which also provided partial support for the post-graduate bursary for the first authorAdditional post-graduate financial support was provided by the Carnegie Corporation of New York under the Regional Initiative for Science Education(RISE)programme of the Carnegie Corporation of New York and the Oppenheimer Memorial Trust(OMT)+1 种基金The Department of Environment,Forestry and Fisheries(DEFF),Chief Directorate:Natural Resource Management Programmes(NRM)Directorate:Operational Support and Planning provided financial support to conduct the sediment sampling programme and post-graduate funding for the second author.
文摘The proposed site for the construction of a new dam(Laleni Dam)on the Tsitsa River in the Eastern Cape,South Africa falls within a high soil erosion zone,which is expected to affect the lifespan of the dam.Estimating the sediment yield of the catchment is important from a management perspective,and thus we designed this study to assess the applicability of the Modified Universal Soil Loss Equation(MUSLE).The original MUSLE was applied to the Inxu River sub catchment,upstream of a proposed dam,over a summer rainfall period extending from October 2016 to April 2017.A modified version of the MUSLE,incorporating a storage module,was later applied over the same period.Model calibration of the MUSLE with and without a storage model was tested against 7 months of recorded daily suspended sediment discharge data.With a storage model,we achieved a percentage bias,coefficient of efficiency and R2 of 2%,0.83 and 0.83,respectively,while without storage the performance statistics were markedly lower.These results suggest that a calibrated MUSLE can provide estimates of sediment yield that are valuable for regional planning,and that the inclusion of a storage component further improves the MUSLE application.Given the complexity of sediment generation and transport processes,a relatively simple empirical MUSLE model is a useful tool for initial sediment yield estimation for planning purposes.
