Evaluating the Amount of Erodability and Sedimentation by Comparing Sediment Weight Model and PSIAC Experimental Model (Case Study: Lali Water Catchment, Khuzestan, Iran)

The upstream water catchments are the main source providing sediments in rivers and sedimentary basins. The balance between the erosion phenomenon and the amount of sediment entering into the basin relies on the geometrical specifications and the morphology of the river along the water catchment direction and the amount and type of the sediments. The sedimentary feed of rivers and basins are changed for the sake of natural factors or human disturbances. The river and basin react against this change in that their shape, morphology, plan and profile get changed due to the increase or decrease of the input sediment into the basin. It is essential to know the sediment amount produced by erodability and sedimentation of upstream basins and effects of projects and also to evaluate the amount of sedimentary load in base studies, civil projects, optimizing rivers and dam construction studies specially calculating the amount of sediment amount entering into the dams’ reservoirs in order to take engineering decisions and related alternatives. Sediment Weight Model and PSIAC Experimental Model are recognized as two common methods calculating the amount of the produced sediment caused by erosion applied in this research. Holistically, these methods have been used and compared. Although the results are almost close to one another, more sediment load has been produced in PSIAC method. As more affective parameters are used to cause erosion and produce sediment in PSIAC experimental model, it is recommended to refer to the results of this method because they are closer to reality.

Using Artificial Neural Network to Estimate Sediment Load in Ungauged Catchments of the Tonle Sap River Basin, Cambodia

Concern on alteration of sediment natural flow caused by developments of water resources system, has been addressed in many river basins around the world especially in developing and remote regions where sediment data are poorly gauged or ungauged. Since suspended sediment load (SSL) is predominant, the objectives of this research are to: 1) simulate monthly average SSL (SSLm) of four catchments using artificial neural network (ANN);2) assess the application of the calibrated ANN (Cal-ANN) models in three ungauged catchment representatives (UCR) before using them to predict SSLm of three actual ungauged catchments (AUC) in the Tonle Sap River Basin;and 3) estimate annual SSL (SSLA) of each AUC for the case of with and without dam-reservoirs. The model performance for total load (SSLT) prediction was also investigated because it is important for dam-reservoir management. For model simulation, ANN yielded very satisfactory results with determination coefficient (R2) ranging from 0.81 to 0.94 in calibration stage and 0.63 to 0.87 in validation stage. The Cal-ANN models also performed well in UCRs with R2 ranging from 0.59 to 0.64. From the result of this study, one can estimate SSLm and SSLT of ungauged catchments with an accuracy of 0.61 in term of R2 and 34.06% in term of absolute percentage bias, respectively. SSLA of the AUCs was found between 159,281 and 723,580 t/year. In combination with Brune’s method, the impact of dam-reservoirs could reduce SSLA between 47% and 68%. This result is key information for sustainable development of such infrastructures.

Distribution of Macro-elements and Natural Radionuclides in the Bottom Sediments and Soils of the Catchment Areas of Small Lakes in the Baikal Region

The examination of macroelements and natural radionuclides in the bottom sediments of small lakes and soils in the catchment areas of the Baikal region allows for the study of the mechanism of inflow and the source of these materials.On the basis of the results of rentgenostructural analysis lake sediments are divided into four types:terrigenous,carbonate, terrigenous-carbonate and organogenic.Through the analysis of gamma-ray spectrometry and ato-

Sediment-Loading Processes in a Forested Catchment: Modeling and Observations

In order to investigate sediment-loading processes in a catchment, the daily time series of river discharge and sediment load were applied to a semi-distributed model, the Soil and Water Assessment Tool (SWAT). The time series of discharge and sediment load were obtained by monitoring the river stage and water turbidity of the Oikamanai River, Hokkaido, Japan, in the rainfall season (April-November) of 2011-2014. The catchment is forested (ca 90% area) but underlain by the Neogene sedimentary rocks with currently active faults and forest soils with tephra layers, which tend to frequently produce slope failure such as landslide and bank collapse by rainfall or snowmelt. The water turbidity, T, in ppm was converted into suspended sediment concentration, SSC, in g/L by applying the linear relationship between T and SSC. The acquisition of the time series of discharge, Q (m3/s) and sediment load, L (=Q·SSC in g/s) of the river allowed us to distinguish the fluvial sediment transport, accompanied by slope failure in the upstream, from that under no slope failure. The SWAT was used to simulate soil erosion and identify the region prone to the soil erosion in the Oikamanai River basin. The model’s results showed a satisfactory agreement between daily observed and simulated sediment load as indicated by the high Nash-Sutcliffe efficiency. This evidences that the upper mountainous region of the catchment provides a main sediment source, accompanied by slope failure.

Estimation of Sediment Yield of Govindsagar Catchment, Lalitpur District, (U.P.), India, Using Remote Sensing and GIS Techniques

Soil erosion is a global phenomenon, which results in sedimentation and siltation of reservoirs of major rivers. Remote sensing data provide a synoptic view from which several surface parameters can be derived to assess the sedimentation yield in the reservoirs. Hence estimation of sediment yield has become one of the important tasks for planners, engineers and decision makers. The present study in Govindsagar catchment, Lalitpur District, Uttar Pradesh (India), has been carried out using IRS LISS III data to analyse land use/cover characteristics besides drainage basin characterstics. Subsequently, Sediment Yield Index (SYI) of Govindsagar catchment has been estimated using surface derivatives and morphometric parameters using empirical formulae. Integration of results obtained from satellite data and morphometric analysis suggests that the Govindsagar catchment has very low rate of sediment yield i.e. 0.07 ha·m/year indicating a gentle slope and sustainable land use practices in the catchment. Low sediment yield also suggests less erosion in the catchment areas and healthy land use/cover scenario.

Slope-gully erosion relationship in small catchments of the middle reaches of the Yellow River

The slope-gully erosion relationship in small catchments of the middle reaches of the Yellow River has long been a topic concerned by relevant departments in China Slope-gully relationship in typical small catchment is determined determined on the concept of net increase of sediment yield by using analytical method of sediment formation at different positions in the catchment The result shows that sediments in a small catchment in the middle reaches of the Yellow River mainly come from slopes. ms paper indicated that the sediment sources from slopes are roughly 55, 60, 78 and 85 % of the total sediment yield of a small catchment in Yangdaogou. Wangjiagou. Jiuyuangou and Nanxiaohegou, respectively, due to impacts of varying degress from slope runoff.

滇中高原不同土地利用类型产流产沙特征及影响因素——以尖山河小流域为例

[目的]研究滇中高原山区小流域不同土地利用类型植被措施的水土保持效益,为合理种植及改善土地利用现状提供科学依据及理论指导。[方法]以玉溪市尖山河小流域为研究区,采集研究区2012-2022年的降雨数据结合径流小区径流量和产沙量数据,研究分析次生林地、人工林地、灌草丛地、农耕地、经果林地径流量和产沙量特征及影响因素。[结果]①径流量排序为:农耕地>经果林地>灌草丛地>次生林地>人工林地,产沙量排序为农耕地>人工林地>经果林地>次生林地>灌草丛地。相同降雨条件下农耕地较其他土地利用类型的抗侵蚀性差。②产沙量与径流量二者之间呈明显的正相关性(p<0.01),产沙相较于产流具有滞后性,当次生林地径流量≥0.02 mm,灌草丛地≥0.46 mm,人工林地≥0.4 mm,经果林地≥0.62 mm,农耕地≥0.09 mm时才会携带泥沙。③径流量和产沙量与植被盖度、降雨特征因子之间的相关性显著(p<0.05),与土壤理化指标中的毛管持水量、毛管孔隙度、总孔隙度之间存在显著相关性(p<0.05),与其余的理化指标相关性不显著(p≥0.05)。[结论]研究区内应科学设置植被类型布局,合理分配土地种植模式,科学布局农田整地。

穿梭山体的线型项目水土保持方案汇水分析特点难点及方法

本文以沙荷路—盐排高速立交工程(二期)项目为例,对穿梭山体的线型项目的原始地形、工程施工建设新形成的边坡改变地形致使汇水方向发生改变进行了分析,根据排水出口承担的汇水面积对截排水沟规格及沉沙池缓冲沉淀效果进行校核及补充设计,以发挥水土保持效用,使施工期水土流失降至容许范围内。

中国钴地球化学基准值特征及影响因素

随着新能源产业的快速崛起,钴的战略价值不断提升,同时钴的潜在生态风险也逐渐受到重视。中国地球化学基准计划(CGB)建立了钴的地球化学基准,为资源评价和环境基准建立提供了定量参照标尺。中国岩石钴的基准值为6.44×10^-6,背景值为9.26×10^-6,与中国出露地壳丰度接近。中国汇水域沉积物/土壤表层、深层钴的基准值分别是11.0×10^-6和10.6×10^-6,略高于其他大陆(国家)钴基准值,略低于中国区域化探水系沉积物钴中位值。岩石和汇水域沉积物或土壤中钴的基准主要受地质背景控制,但在化学风化作用强烈和碳酸盐岩发育的区域,汇水域沉积物/土壤中钴的基准值发生富集作用。

贵州茂兰峰丛森林洼地泥沙堆积速率的^137Cs示踪研究

选择黔南峰丛洼地区的茂兰自然保护区的坡格森林洼地典型小流域,进行了泥沙堆积的137Cs示踪研究。(1)坡格森林洼地底部的土壤剖面属于农耕地剖面。(2)受岩土分布、微地形和土壤异质性的影响,137Cs初始沉降后的再分布不均匀,137Cs面积活度变异系数为1.54。相同组成特征的地块内部样点137Cs面积活度变异系数变化为0.36～0.54,变异相对较小。但137Cs面积活度不能表征土壤侵蚀状况。(3)典型沉积剖面B-1的单一137Cs峰值浓度出现在14～16cm,高浓度137Cs均匀分布深度小于当地犁耕层厚度20cm,说明1963年以来坡格森林洼地的堆积速率接近于0。

金沙江干热河谷典型区段水土流失特征

以金沙江干热河谷典型区段不同处理坡面和林地、农地集水区为研究对象,采用坡面径流小区和集水区卡口站三角形薄壁堰实测法,在坡面径流小区和集水区土地利用现状调查基础上,通过降雨、径流及泥沙观测,分析金沙江干热河谷典型区段水土流失特征。结果表明:(1)不同处理坡面径流小区产流量、产沙量大小依次为坡耕地>自然坡面>水平阶整地>反坡台整地,表明反坡台和水平阶造林整地以及植被良好的自然坡面对地表径流的拦蓄和对泥沙的削减都起到较好效果;(2)大暴雨对集水区尺度产流产沙贡献值大,产流降雨量在4.8～27.6mm区间,农地集水区径流深小于林地集水区,大于27.6mm时,农地集水区径流深反超林地集水区,而产沙量不受降雨量影响,为林地集水区低于农地集水区;(3)径流小区尺度与集水区尺度雨季水土流失起止时间一致,集水区径流系数小于径流小区,集水区产沙量大于径流小区。

湘西山地不同植被类型的水土保持效益研究

根据 6种不同植被径观测流场资料分析发现 :1荒山的坡面年产流量比 5种有林地的坡面年产流量要大11.37% ;不同林分类型坡面年产流量相差 83.19% ;2荒山坡面年产沙量、输沙率比有林地坡面要大 2 38%～381%、335 %～ 779% ;天然次生林的坡面年产沙量、输沙率为经济林的 5 4 .35 %、6 5 .4 5 % ,林分保土效益大于保水效益 335倍 ;3林地土壤侵蚀模数逐渐减少 ,造林 5年后 ,可使造林前的中度流失降低到轻度流失 ;4坡耕地土壤侵蚀模数为 5 5 80 t/ (km2 · a) ,比荒山的土壤侵蚀模数还要大 110 t/ (km2 · a)

鄂尔多斯盆地天然气成藏特征

鄂尔多斯盆地天然气资源丰富,含气层系多,具有上、下古生界复合含气的特征,已发现4 个储量达到1×1011 m3 以上的大型气田。通过对生烃、沉积、储层、圈闭保存条件等的综合研究,认为上古生界具有煤系地层“广覆式”生气特色,三角洲分流河道中粗粒石英砂岩是上古生界高效储层的主要岩石类型,圈闭以大型岩性圈闭为主,天然气成藏条件优越,勘探领域广阔,仍具有发现大型气田的地质条件;下古生界具有混源气特征,白云岩风化壳岩溶储层是主要储集岩类型,圈闭以古地貌—岩性复合圈闭为主,勘探潜力较大。

结合粒度和^(137)Cs对小流域水库沉积物的定年——以黔中喀斯特地区克酬水库为例

对取自黔中喀斯特地区克酬水库32cm长沉积物柱样进行137Cs比活度以及粒度测定,结合气象站点降雨数据进行比对分析,对沉积物不同层位的年代进行了划分,并以此结合质量深度推算了1960-2004年间该水库的沉积速率.结合实例分析了137Cs沉降、运移和沉积,改进了仅依靠137Cs峰值定年方法,认为在流域面积较小、137Cs比活度测试绝对数值较小的流域,降水和其他条件造成的土壤侵蚀程度差异可能是造成土壤中137Cs进入湖泊沉积物多少的更主要原因,并表现为沉积物中137Cs不同层位的差异.

纸坊沟流域土壤侵蚀与产沙初步研究

在综合分析的基础上，阐明了纸坊沟流域土壤侵蚀与产沙背景、土壤侵蚀特征、产沙特征及综合治理减沙效益，并提出了减沙效益进一步分析的建议．

云南属都湖沉积物金属元素地球化学

通过对属都湖短岩芯Esdr1重金属元素的分析,结合沉积物粒度、流域降水和人类活动资料,讨论属都湖沉积物金属元素地球化学变化特征.结果表明,沉积物中Al、Mg、Co、Zn、Cr、Ti、V、Cu、Ni等元素含量变化与粘土含量、夏季降水量显著相关,降水导致的流域侵蚀强弱变化是影响元素含量变化的主要因素.元素Pb含量从岩芯底部到顶部总体呈上升趋势,25-17.5cm沉积物中Pb含量较稳定主要为自然侵蚀过程控制;17.5-10.5cm沉积物中Pb含量迅速增加后逐渐降低推测为20世纪50年代湖区附近矿山开采产生的粉尘沉降的影响;10.5-0cmPb含量逐渐增加,80年代以后大气中Pb含量上升,Pb在流域的干湿沉降应是岩芯上部Pb含量升高的原因.在氧化还原作用下沉积物中Fe、Mn易在沉积物-水界面发生再迁移,25-7.5cm沉积物中的Fe、Mn含量变化特征为沉积后再迁移作用的结果;7.5-0cmFe和Mn含量明显上升,夏季降水量增加导致流域侵蚀增强和土壤的潜育化可能是岩芯上部Fe、Mn含量显著上升的原因.

黄土高原小流域植被变化和侵蚀产沙的孢粉示踪研究初探

如同137Cs和210Pbex核尘埃,土壤和坝库沉积物中的孢粉也源于大气沉降,是否能用于侵蚀产沙的示踪研究?在陕北吴旗周湾水库采集了一些表层土壤和现代淤地坝、古代聚湫坝沉积泥沙的样品,尝试土地利用/覆被变化和侵蚀产沙的孢粉示踪研究。初步研究表明:草地表土孢粉丰富,平均浓度为26077粒/g;有33个科属的花粉,孢粉组合反映了当地以蒿属为主的半干旱温带草原植被;坡耕地表土的孢粉组合和草地一致,但孢粉平均浓度远低于草地,仅5844粒/g。坝库沉积剖面中,和137Cs核素一样,孢粉也富集于每一洪水沉积旋迴的上部层位,可用于沉积旋迴的区分。现代沉积旋迴的孢粉平均浓度,远低于草地和坡耕地表土,这表明草地和坡耕地土壤不是沉积泥沙的主要来源。古代沉积物的孢粉平均浓度高于现代沉积,表明流域内300年前的植被好于现代,或300年前沟谷地的相对产沙量低于现代。古代孢粉组合中十字花科花粉比例高达36·85%,明显高于现代的0·58%含量,这表明草地退化严重,十字花科植物比例急剧降低。孢粉示踪技术在植被环境恢复,沉积旋迴区分,和泥沙来源确定等方面具有一定的潜力,但应建立针对土地利用/覆被变化和侵蚀产沙研究的孢粉示踪技术方法。

复合指纹识别泥沙来源:潜在泥沙源地的选择

复合指纹识别技术应用于泥沙源解析的前提是假设研究者能够确定流域内泥沙的潜在来源类型，并且各泥沙源地所占比例之和为1，对潜在源地预判的不确定性将会对结果产生一定的影响。以南京市九乡河上游流域为例，对不同源地各指纹因子做均值显著性检验，检验各个预判源地能否单独作为潜在泥沙源地，同时对比分析不同沙源地对复合指纹因子判断泥沙来源正确率的影响，定量分析沙源地预判过程中的不足，探讨如何减少沙源地选择对泥沙来源识别的影响。通过对比研究发现，预判的4种泥沙源地被重新调整为农田、林地和道路3种类型。调整后各源地指纹因子差异性明显提高，不同泥沙来源的正确判别率最高达到89？2％，泥沙贡献率从高到低依次为农田（39.9％～87.8％）、林地（＜0.1％～47.7％）和道路用地（0～25.6％）。

坝地沉积旋回泥沙养分变化及其对小流域泥沙来源的解释

黄土高原广泛分布的坝地沉积泥沙中赋存了大量小流域侵蚀特征及侵蚀环境变化的信息,泥沙特性的变化则是这些信息的直接体现。该文通过对比分析淤地坝沉积旋回泥沙中和坝控小流域内不同泥沙源地土壤中有机质、全氮、全磷和全钾的含量,发现小流域内土壤养分含量变异性明显大于沉积旋回泥沙中的变异性,沉积旋回泥沙养分含量与沟壁土壤中的相接近,其中与沟壁中的全氮、全磷和全钾无显著差异(p>0.05),但显著小于荒草地和坡耕地中的有机质、全氮和全磷含量(p<0.05),表明淤地坝运行期间小流域泥沙主要来源于沟壁坍塌和沟道扩展,重力侵蚀和沟蚀是主要侵蚀类型;有机质和全氮在坝地沉积旋回中呈明显阶段性变化,分析认为其反映了农村土地联产承包责任制对小流域土地利用和土壤侵蚀的影响。