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.

Depositional and Structural Styles in the Logone Birni Basin (LBB), Northern Cameroon, from 3D Potential Field Modeling: Preliminary Results

A three-dimensional model of the Logone Birni Basin (LBB) is presented by combining gravity and magnetic data and constrained by broad seismic profiles. The 3-D model has revealed the distribution of the stratigraphic formations as well as the top basement variation. Detailed structure of different stratigraphic sequences is presented for the first time for this basin and some of the sequences correlate with established sequences of the neighboring basins. The sediments pill consists of six sedimentary units dating from the Neocomian to the Quartenary. The Makary subbasin or Northern Logone Birni Basin (NLBB) is the deepest part of the basin and may hold good prospect for hydrocarbon generation and accumulation. However, the limited presence of faults and intrusive bodies decreases the possibility of thermal degeneration, contrary to the Central Logone Birni Basin (CLBB) where conditions seem to be fulfilled for possible hydrocarbon generation and maturity. The complexity of the structural pattern of the model is further enhanced by the presences of volcanic bodies, some of which lay directly on basement or interbedded with the sediments layers mainly in the CLBB.

陆相坳陷湖盆细粒沉积岩岩相类型及成因——以松辽盆地晚白垩世青山口组为例

页岩油是目前非常规油气研究的热点与难点。细粒沉积岩岩相类型及成因分析是页岩油“源储”特征研究及“甜点”预测的有效途径。松辽盆地青山口组细粒沉积广泛发育,是页岩油富集的有效层段。本文通过岩性、矿物成分、有机质丰度与沉积构造4个参数,将松辽盆地青山口组细粒沉积岩划分为6种岩相:高有机质泥纹层黏土质页岩(A)、中高有机质含细粉砂纹层长英质页岩(B)、中低有机质含粗粉砂纹层长英质页岩(C)、低有机质层状粉砂岩(D)、低有机质层状介形虫灰岩(E)和低有机质层状白云岩(F)。进一步从水动力学与有机质富集方面探讨了不同岩相类型的成因,并建立了相应的沉积模式。具体为:在风暴浪基面之下的静水、咸水环境、高湖泊生产力背景中,浮游藻类与黏土絮状物均匀悬浮沉降,形成贫富有机质黏土质纹层,沉积A岩相;在正常浪基面之下的相对静水(浪基面附近局部动荡)、半咸水环境、高湖泊生产力背景中,三角洲径流与洪流带来的细粉砂颗粒继续向湖盆中央搬运,经均匀悬浮沉降形成长英质纹层,间歇期悬浮沉降形成黏土质纹层,形成B岩相;正常浪基面之下,洪水携带粉砂级颗粒,顺着水下分流河道搬运至外前缘,以稳定性浊流的形式进入前三角洲,随流速逐渐降低,分异形成粗粉砂—细粉砂纹层,间歇期悬浮沉降形成黏土质纹层,形成C岩相;正常浪基面之下,三角洲前缘早期沉积物在阵发性浊流的作用下,滑塌至较深水区,形成D和E岩相;于正常浪基面与风暴浪基面之间,在相对干燥的气候背景下的咸水环境中,形成F岩相。

The Research and Application of BP Neural Networks in River-basin Water and Sediment

Based on the basic principles of BP artificial neural network model and the fundamental law of water and sediment yield in a river basin, a BP neural network model is developed by using observed data, with rainfall conditions serving as affecting factors. The model has satisfactory performance of learning and generalization and can be also used to assess the influence of human activities on water and sediment yield in a river basin. The model is applied to compute the runoff and sediment transmission at Xingshan, Bixi and Shunlixia stations. Comparison between the results from the model and the observed data shows that the model is basically reasonable and reliable.

Lithologic Hydrocarbon Deposits in Rift Lake Basins in Eastern China

The rift lake basins in the eastern China have abundant hydrocarbon resources of lithologic deposits, which resulted from excellent source rocks and multi-type sandbodies developed during strong rifting. Vertically, the lithologic deposits are mainly distributed in the lowstand, lacustrine invasion and early highstand systems of third-order sequence corresponding to a secondary tectonic episode of strong rifting, and laterally they are closely related to various fans and turbidite sandbodies controlled by syn-sedimentary faults. A variety of lithologic traps have been developed in the rift lake basins, and they generally have favorable conditions of source-reservoir-seal assemblage and hydrocarbon accumulation dynamics, indicating that there is a great exploration potential of lithologic deposits in the rift lake basins. In order to obtain satisfactory effects of lithologic deposit exploration, it is required to combine new theories with advanced technical methods.

Coupling Singular Spectrum Analysis with Artificial Neural Network to Improve Accuracy of Sediment Load Prediction

Sediment load estimation is generally required for study and development of water resources system. In this regard, artificial neural network (ANN) is the most widely used modeling tool especially in data-constraint regions. This research attempts to combine SSA (singular spectrum analysis) with ANN, hereafter called SSA-ANN model, with expectation to improve the accuracy of sediment load predicted by the existing ANN approach. Two different catchments located in the Lower Mekong Basin (LMB) were selected for the study and the model performance was measured by several statistical indices. In comparing with ANN, the proposed SSA-ANN model shows its better performance repeatedly in both catchments. In validation stage, SSA-ANN is superior for larger Nash-Sutcliffe Efficiency about 24% in Ban Nong Kiang catchment and 7% in Nam Mae Pun Luang catchment. Other statistical measures of SSA-ANN are better than those of ANN as well. This improvement reveals the importance of SSA which filters noise containing in the raw time series and transforms the original input data to be near normal distribution which is favorable to model simulation. This coupled model is also recommended for the prediction of other water resources variables because extra input data are not required. Only additional computation, time series decomposition, is needed. The proposed technique could be potentially used to minimize the costly operation of sediment measurement in the LMB which is relatively rich in hydrometeorological records.

渌水流域水沙演变规律及其对土地利用变化的响应研究

【目的】探究渌水流域土地利用变化对水沙变化的影响。【方法】基于遥感影像数据及实测水沙数据,分析渌水流域水沙变化趋势及其对土地利用变化的响应,进一步构建CA-Markov城市扩张模型及水文模拟模型(hydrologic simulation program-Fortran,HSPF),量化土地利用变化和气候变化对水沙的影响;基于模型开展渌水流域未来土地利用情景预测及未来水沙过程模拟。【结果】1980年以来渌水流域内建设用地面积持续增长,渌水流域实测径流量呈增加趋势,输沙量呈减少趋势,两者的突变点分别在1988年及1998年;气候变化和人类活动对径流增加的贡献率分别为49.53%、50.47%,对输沙减少的贡献率分别为3.45%和96.55%;实施耕地保护政策的2030年土地利用情景在保障耕地面积的同时,并未明显加剧水土流失问题,还能兼顾社会经济发展和城市化建设。【结论】1988年之后渌水流域径流量增加是土地利用变化和气候变化共同作用的结果;而1998年之后流域输沙量显著减少的主要原因为土地利用变化。

湟水流域绿水管理模拟与水-沙-质协同调控效果评价

在黄河流域生态保护和高质量发展战略背景下,流域上游实施绿水管理对于涵养水源、保护脆弱生态,以及缓解流域缺水形势具有重要意义。选取黄河流域上游的湟水流域构建SWAT水文模型,模拟等高耕作、残茬覆盖、石线、梯田和15°以上坡地退耕还林等5种绿水管理措施,分析水量、水沙和水质的变化;结合水-沙-质管理协同水平,探究不同措施的效果与适用性。结果表明,15°以上坡地退耕还林在增加产水量和地下水补给方面效果最优,分别为1.77×107m3和1.72×107m3;等高耕作和石线能有效调节年内径流分配、削减汛期径流量。5种措施均能削减产沙负荷,其中梯田和石线的效果较显著,削减率分别为13.5%和13.0%。5种措施均能减少总氮(TN)和总磷(TP)负荷量,且干旱年削减率高于湿润年;梯田和等高耕作削减效果较好,削减率分别为24.6%、14.7%(TN)和45.3%、21.9%(TP)。通过水-沙-质管理协同分析,除残茬覆盖为高等耦合外,其他4种情景下均能达到优等耦合;耦合协调度由大到小依次为梯田、15°以上坡地退耕还林、石线、等高耕作、残茬覆盖。研究结果可为黄河流域绿水管理措施选取和水资源优化配置提供参考。

准噶尔盆地玛湖凹陷风城组沉积环境与沉积模式分析

玛湖凹陷是准噶尔盆地重要的生烃凹陷,其下二叠统风城组作为主力烃源岩,也是重要的勘探层系。风城组的岩相展布与沉积模式的研究,对明确玛湖凹陷的构造演化过程和油气勘探具有重要的参考意义。基于最新的测井、录井资料,建立玛页1井风城组综合柱状图,查明玛湖凹陷风城组岩相展布,进而重建玛湖凹陷下二叠统风城组各沉积时期的沉积环境,明确沉积模式。研究结果表明,玛页1井风城组主要为黑色-灰黑色细粒沉积岩,大量发育软沉积变形构造,说明玛北地区风城组主要为半深湖-深湖亚相沉积。根据连井岩相剖面,玛湖凹陷风城组自下而上发育进积-退积-进积的旋回特征,自南西向北东方向为扇三角洲相-湖泊相-河流三角洲相沉积。风一段火山岩火山活动强烈,玛北地区发育水下熔结凝灰岩、火山碎屑岩及玄武岩,主要为浅湖沉积。风二段玛南地区为扇三角洲沉积,向玛西地区过渡为三角洲-滨浅湖沉积,玛北地区发育半深湖-深湖沉积,在湖盆中心发育碱性矿物沉淀;风二段中部化学沉淀分布范围最广,指示最大洪泛面。风三段进积作用加强,湖盆萎缩,玛南、玛西地区发育扇三角洲沉积,玛北地区发育半深湖-滨浅湖沉积。结合其沉积演化过程,玛湖凹陷风城组是受到外源碎屑沉积、内源化学沉淀和火山碎屑物质等影响的多源混积沉积模式。

长周期波大输沙量条件下海港平面布置方案

随着“一带一路”的建设,西非、地中海以及印度洋沿岸等海域由于其特定的自然条件导致具有明显的长周期波浪成分,且已对港口工程建设产生了严重影响。结合非洲某港口工程实例,其具有波浪周期长以及沿岸输沙量大两大特点;长周期波及大输沙量易引起港内泊稳条件差、泥沙淤积重,外海船舶施工风险大等问题,经对其平面布置方案研究后,决定采用挖入式港池布置方案,并通过波浪泥沙数学模型及物理模型试验等研究方法进行验证。结果表明,该挖入式港池方案能较好地解决以上问题。

黑河沉积物氮、磷和有机质的空间分布特征及来源解析

【目的】研究黑河流域沉积物营养盐空间分布特征及对其来源进行解析。【方法】采用多元线性回归模型和冗余分析方法定量分析了不同缓冲区尺度土地利用类型对营养盐的解释度及对其变异的解释能力。【结果】黑河流域沉积物的总磷(TP)、总氮(TN)、硝态氮(NO_(3)^(-)N)、氨态氮(NH_(3)^(-)N)和有机碳(TOC)含量均值分别为224.83、245.32、55.76、30.25和8.42 mg/kg。从空间分别来看,总氮(TN)、总磷(TP)在中游自然河段的含量较高,在上游支流河段的含量较低;各尺度土地利用类型与沉积物营养含量密切相关。【结论】本研究阐明了建设用地、灌丛是黑河流域沉积物有机碳(TOC)、硝态氮(NO_(3)^(-)N)的主要来源。这可为该流域的生态环境保护与治理提供参考。

蒋家沟流域输沙预测模型初探

从时间和控制因子两个角度 ,初步探讨了蒋家沟流域产沙预测模型。结果表明 ,由周期预测和控制因子预测组成的综合预测模型 ,可对蒋家沟泥石流的输沙进行较为可靠的预测。同时 ,在探讨了模型存在的及有待改进的问题的基础上 ,还对综合预测模型进行了探讨。

黄河流域多沙粗沙区植被覆盖变化与减水减沙效益分析

通过遥感手段和数字流域模型,研究了黄河流域多沙粗沙区近10来年的植被覆盖变化及其减水减沙效益。研究表明,多沙粗沙区90年代末期与80年代末期相比,植被覆盖度增加区域大约占50%,植被覆盖度没变化区域约占48%。植被覆盖度的变化导致了流域水沙条件的变化,90年代末期植被覆盖条件下,植被措施的减水减沙百分比不高;不同的降雨过程,植被措施的减水减沙效益有一定的差别;从不同降雨过程多年平均看,近10来年植被措施年均减水2.63亿m3,减沙1.13亿t,减水减沙比为2.75,即减1亿t沙的同时减水2.75亿m3,减水百分比为7.61,减沙百分比为10.56,减沙效益大于减水效益。

湛江湾填海工程对海床冲淤的影响预测

建立了湛江湾泥沙数学模型,模拟了湛江湾海床冲淤演变,模拟结果表明,湛江湾海床较为稳定,年冲淤强度小,模拟冲淤分布与历史海图资料得出的长期演变趋势符合。模型用于湛江湾围填工程对海床冲淤变化的影响预测,结果表明工程后海床冲淤强度没有明显的改变。另外,优选了围填方案,估计了港池的淤积强度。

挖入式港池泥沙淤积试验研究

在水槽试验的基础上,结合部分理论分析,初步研究了挖入式港池的泥沙淤积问题的原因、泥沙运动以及淤积特性。结果表明:含沙量分布具有一定的规律,口门处淤积量较大,泥沙粒径较粗,而港池内部淤积量较小,粒径较细。因此,采取适当措施减少该形式港池口门处的淤积是十分必要的。

利用岩石圈瞬态热流模型重建渤海湾盆地新生代热历史

以孔隙度、热导率、地层温度及镜质体反射率数据作为校准，利用BasinMod软件建立了一维岩石圈瞬态热流模型，挑选渤海湾盆地内资料相对齐全且靠近沉积一沉降中心的9口深钻孔，对新生界地层热历史进行了重建。模型中考虑了沉积压实、非均一热导率结构、沉积层和地壳的放射性生热以及沉积充填和剥蚀作用的热效应。作为检验和对比，模拟了双层伸展裂谷模型热流和不变的现今热流两种情形，结果表明：除了东营末期剥蚀地层厚度较大的局部地区以外，渤海湾盆地大部分地区新生界沉积层的现今地层温度皆因深埋作用而处于其所经历的最高温度，但现今热流却不是其经历的最大热流；最大热流出现在东营组地层遭受剥蚀的末期，距今约16-20Ma，最高地表热流值高于现今9％～23％。简单裂谷热流模型不能反映由古温标和井底温度所记录的热流史，而瞬态模型包含了更多的地质信息，考虑了更多的影响因素，由此所预测的热历史可能与渤海湾盆地岩石圈和沉积层在新生代期间所经历的实际热演化史更加吻合。

渭河流域产流产沙模型及径流泥沙变化原因分析

考虑渭河水沙变化特性 ,根据水量平衡原理及产沙机制 ,应用天然时期的气象、水文资料建立了渭河产流产沙模型 ;采用水文模拟途径外延了人类活动影响期间的天然径流、泥沙过程 ,进而分析了渭河水沙变化原因。结果表明 :1970～ 1995年 ,渭河华县站年均径流、泥沙量较前期分别减少 2 5.9亿 m3和 1.11亿 t,其中 58.3%和 55.7%是由人类活动影响所致 。

前陆盆地形成与演化砂箱物理模拟启示--以四川盆地西部龙门山为例

通过砂箱物理模拟实验揭示冲断带-前陆盆地系统形成演化过程中,单一构造剥蚀、沉积作用和剥蚀-沉积耦合过程对其盆-山系统形成演化的控制影响作用,尤其聚焦于龙门山-川西前陆盆-山系统沿走向变化的构造剥蚀-沉积作用对其盆-山系统的控制作用。单一构造剥蚀作用过程模拟揭示浅表剥蚀作用强度与冲断带楔形体楔长、楔高呈负相关性;构造剥蚀作用使冲断带后缘逆冲断层更加易于发生断层再活化与无序冲断,制约着冲断带前陆向扩展。浅表沉积作用导致楔形体前缘冲断层上覆物质加载、更易于发生断层闭锁,促使冲断带楔形体前陆向/前展式扩展生长。沿走向变化的剥蚀-沉积作用过程导致冲断带楔形体后缘深部层系剥蚀走向变化、断层产状变陡,前陆盆地中前陆向断层明显减小、其倾角减缓,且反向冲断作用加强(乃至导致主断层反向冲断),尤其走向差异性导致前陆盆地发育斜向断层。受控于龙门山冲断带-川西前陆盆地系统晚三叠世以来走向差异性剥蚀-沉积作用,川西前陆盆地中南段发育晚白垩世—新生代再生前陆盆地,可能形成前陆盆地前缘斜向断层-龙泉山断层。

中大流域水沙耦合模拟物理概念模型

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