Intensity of in‐lake processes in floodplain lakes within the Bug River zone of fluvial activity          下载免费PDF全文

Jarosław Dawidek  Beata Ferencz 《水文研究》2014,28(24):5965-5971

The paper presents a new approach to calculating the erosion and deposition values of floodplain lake basins, the erosion–deposition index (EDI). The EDI is a sum of the basin geometry indices (BGIs), which can be calculated for a separate cross section of the lake. The distribution of processes within the basin was investigated in two selected floodplain lakes with the use of BGIs. Field research was carried out in the Bug River valley from 1 November 2006 to 31 October 2011. The highest erosion was observed in the lakes located close to the parent river. Deposition processes were observed in lakes with high inflow of groundwater. The results showed that EDI values of 48 out of the 71 floodplain lakes ranged from ?0.2 to 0.2. Spatial distribution of erosion and deposition processes within the lake basins resulted from a velocity of water inflowing or flowing through the basin. This was observed especially in contrafluent–confluent lake. Inflow of rivers water via upstream crevasse occurred later than via downstream one, but energy of flowing water was higher, which favoured erosion of this part of the lake basin. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Modelling sediment deposition and phosphorus retention in a river floodplain          下载免费PDF全文

M. González‐Sanchis  J. Murillo  A. Cabezas  J. E. Vermaat  F. A. Comín  P. García‐Navarro 《水文研究》2015,29(3):384-394

Phosphorus (P) is one of the major limiting nutrient in many freshwater ecosystems. During the last decade, attention has been focused on the fluxes of suspended sediment and particulate P through freshwater drainage systems because of severe eutrophication effects in aquatic ecosystems. Hence, the analysis and prediction of phosphorus and sediment dynamics constitute an important element for ecological conservation and restoration of freshwater ecosystems. In that sense, the development of a suitable prediction model is justified, and the present work is devoted to the validation and application of a predictive soluble reactive phosphorus (SRP) uptake and sedimentation models, to a real riparian system of the middle Ebro river floodplain. Both models are coupled to a fully distributed two‐dimensional shallow‐water flow numerical model. The SRP uptake model is validated using data from three field experiments. The model predictions show a good accuracy for SRP concentration, where the linear regressions between measured and calculated values of the three experiments were significant (r² ≥ 0.62; p ≤ 0.05), and a Nash–Sutcliffe coefficient (E) that ranged from 0.54 to 0.62. The sedimentation model is validated using field data collected during two real flooding events within the same river reach. The comparison between calculated and measured sediment depositions showed a significant linear regression (p ≤ 0.05; r² = 0.97) and an E that ranged from 0.63 to 0.78. Subsequently, the complete model that includes flow dynamics, solute transport, SRP uptake and sedimentation is used to simulate and analyse floodplain sediment deposition, river nutrient contribution and SRP uptake. According to this analysis, the main SRP uptake process appears to be the sediment sorption. The analysis also reveals the presence of a lateral gradient of hydrological connectivity that decreases with distance from the river and controls the river matter contribution to the floodplain. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Variability in the vertical hyporheic water exchange affected by hydraulic conductivity and river morphology at a natural confluent meander bend          下载免费PDF全文

Jinxi Song  Guotao Zhang  Weize Wang  Qi Liu  Weiwei Jiang  Weiqiang Guo  Bin Tang  Haifeng Bai  Xinyi Dou 《水文研究》2017,31(19):3407-3420

River confluences and their associated tributaries are key morphodynamic nodes that play important roles in controlling hydraulic geometry and hyporheic water exchange in fluvial networks. However, the existing knowledge regarding hyporheic water exchange associated with river confluence morphology is relatively scarce. On January 14 and 15, 2016, the general hydraulic and morphological characteristics of the confluent meander bend (CMB) between the Juehe River and the Haohe River in the southern region of Xi'an City, Shaanxi Province, China, were investigated. The patterns and magnitudes of vertical hyporheic water exchange (VHWE) were estimated based on a one‐dimensional heat steady‐state model, whereas the sediment vertical hydraulic conductivity (K_v) was calculated via in situ permeameter tests. The results demonstrated that 6 hydrodynamic zones and their extensions were observed at the CMB during the test period. These zones were likely controlled by the obtuse junction angle and low momentum flux ratio, influencing the sediment grain size distribution of the CMB. The VHWE patterns at the test site during the test period mostly showed upwelling flow dominated by regional groundwater discharging into the river. The occurrence of longitudinal downwelling and upwelling patterns along the meander bend at the CMB was likely subjected to the comprehensive influences of the local sinuosity of the meander bend and regional groundwater discharge and finally formed regional and local flow paths. Additionally, in dominated upwelling areas, the change in VHWE magnitudes was nearly consistent with that in K_v values, and higher values of both variables generally occurred in erosional zones near the thalweg paths of the CMB, which were mostly made up of sand and gravel. This was potentially caused by the erosional and depositional processes subjected to confluence morphology. Furthermore, lower K_v values observed in downwelling areas at the CMB were attributed to sediment clogging caused by local downwelling flow. The confluence morphology and sediment K_v are thus likely the driving factors that cause local variations in the VHWE of fluvial systems.  相似文献   

Paleogene of the Huanghekou Sag in the Bohai Bay Basin,NE China: deposition–erosion response to a slope break system of rift lacustrine basins     

Hao Liu  Qinglong Xia  Ian D. Somerville  Yuan Wang  Xinhuai Zhou  Chengmin Niu  Xiaofeng Du  Xintao Zhang 《Geological Journal》2015,50(1):71-92

The sequence architecture and depositional systems of the Paleogene lacustrine rift succession in the Huanghekou Sag, Bohai Bay Basin, NE China were investigated based on seismic profiles, combined with well log and core data. Four second‐order or composite sequences and seven third‐order sequences were identified. The depositional systems identified in the basin include: fan delta, braid delta, meander fluvial delta, lacustrine and sublacustrine fan. Identification of the slope break was conducted combining the interpretation of faults of each sequence and the identification of syndepositional faults, based on the subdivision of sequence stratigraphy and analysis of depositional systems. Multiple geomorphologic units were recognized in the Paleogene of the Huanghekou Sag including faults, flexures, depositional slope break belts, ditch‐valleys and sub‐uplifts in the central sag. Using genetic division principles and taking into consideration tectonic features of the Paleogene of the Huanghekou Sag, the study area was divided into the Northern Steep Slope/Fault Slope Break System, the Southern Gentle Slope Break System and T10 Tectonic Slope Break System/T10 Tectonic Belt. Responses of slope break systems to deposition–erosion are shown as: (1) basin marginal slope break is the boundary of the eroded area and provenance area; (2) ditch‐valley formed by different kinds of slope break belts is a good transport bypass for source materials; (3) shape of the slope break belt of the slope break system controls sediments types; (4) the ditch‐valley and sub‐sag of a slope break system is an unloading area for sediments; and (5) due to their different origins, association characteristics and developing patterns, the Paleogene slope break belt systems in the Huanghekou Sag show different controls on depositional systems. The Northern Fault Slope Break system controls the deposition of a fan delta‐lacustrine‐subaqueous fan, the Southern Gentle Slope Break system controls the deposition of a fluvial–deltaic–shallow lacustrine and sublacustrine fan, and the T10 Tectonic Slope Break System controls the deposition of shallow lacustrine beach bar sandbodies. The existence of a slope break system is a necessary but not a sufficient condition for studying sandbody development. The formation of effective sandbodies along the slope break depends on the reasonable coupling of effective provenance, necessary association patterns of slope break belt, adequate unloading space and creation of definite accommodation space. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

香港世界地质公园晚侏罗世荔枝庄组岩石组合及其成岩地质过程解析     

姜杨  杨家明  杨祝良  沈加林  马雪  陈羽岚  钱迈平  邢光福  余明刚  段政 《地质论评》2016,62(3):759-769

中国东南大陆晚侏罗世地层普遍缺失,仅零星见于个别地区,香港新界东北的荔枝庄组即为其一。荔枝庄组出露于香港世界地质公园沉积岩园区的荔枝庄地区,自下往上由火山岩—沉积岩—火山岩组合而成,沉积岩中发育大型包卷层理和滑塌构造等典型沉积构造,是香港地区最具代表性的晚侏罗世火山—沉积岩系。通过实测地层剖面研究,确定其成岩过程大体上可划分为早期普林尼式火山爆发、中期破火山口湖相沉积和晚期普林尼式火山爆发三个阶段,以湖相沉积作用为主、火山喷发作用为辅;受晚期火山岩浆活动的影响,沉积岩层普遍发生硅化或炭化。荔枝庄组独特的岩石组合与形成的古地理环境,为探讨中国东南大陆中生代火山活动—沉积作用方式与成岩过程,提供了难得的研究实例。  相似文献   

陕北风沙区含砾石工程堆积体坡面产流产沙试验   总被引：1，自引：0，他引：1       下载免费PDF全文

康宏亮  王文龙  薛智德  郭明明  李建明  白芸  邓利强  李艳富 《水科学进展》2016,27(2):256-265

采用室内人工模拟降雨方法,研究了陕北风沙区含砾石工程堆积体边坡的产流产沙过程。结果表明:①砾石存在改变了坡面入渗速率,径流系数受入渗速率的影响,随砾石含量的增加先线性递减后线性递增,并在10%砾石含量处存在阈值;径流系数随降雨强度的增加线性递增。②含砾石堆积体坡面流速较纯土堆积体降低,且随雨强增大,砾石延缓径流流动的作用越显著;雨强对径流流速的影响随砾石含量增加持续减弱。③土壤剥蚀率在产流24~33 min后显著增加,砾石主要对显著增加后的平均剥蚀率产生影响。④雨强1.0 mm/min时,砾石存在促进降雨侵蚀,产沙量增大;雨强大于1.0 mm/min时,砾石具有显著的减沙效应。  相似文献   

Magnetic Influences of Cement Dust on Soil in Industrial Area and Its Environmental Implications   总被引：1，自引：0，他引：1  

Li Yong  Zhao Yingquan  Yao Jie 《地球科学进展》2016,31(8):829-839

To monitor environmental implications of cement dust on soil in industrial area, magnetic parameters and mineral compositions were measured by the samples of the cement dust, cement factory dustfall, cement, coal ash, topsoil of green space in the factory and topsoil outside the factory. Results showed that the major magnetic minerals in the samples were magnetite, the magnetic mineral particle size of cement dust, dustfall, cement and coal ash was coarse Multi-Domian (MD) and Pseudo-Single-Domain (PSD). As topsoil of green space in the factory and topsoil outside the factory were polluted by cement dust, their magnetic properties had been obviously changed; the concentration of magnetic minerals elevated and particle size became coarser. The magnetic parameters (χ_fd,χ_ARM/χ,χ_ARM/SIRM) value can reflect the pollution level of the soil, the lower its value was, the more serious soil was polluted. X-ray diffraction results showed that the mineral compositions of the topsoil of green space in the factory and topsoil outside the factory were quartz and calcite, which were the same as cement dust. Magnetic parameters combination characteristics of topsoil can monitor the soil environmental changes in cement industry area.  相似文献   

Holocene overbank deposition in the drainage basin of Lake Khanka     

V.B. Bazarova  M.S. Lyashchevskaya  T.R. Makarova  R.A. Makarevich  L.A. Orlova 《Russian Geology and Geophysics》2018,59(11):1410-1418

Overbank deposits in the Komissarovka River valley consist of alternating silt, clay silt, sand, and soils produced by lacustrine, alluvial, and aeolian deposition and by soil formation. Silt and sand layers in the lower part of the section correlate with the events of Early Holocene transgression and Middle Holocene regression of Lake Khanka. Deposition in the lowermost reaches of the Komissarovka River provides a faithful record of local Holocene landscapes controlled by level changes in Lake Khanka.  相似文献   

甘肃省肃南县桦树沟铁铜矿床地质特征及成矿模式     

李生全 《地质与勘探》2018,54(S1):1383-1391

甘肃北祁连西段桦树沟铁铜矿床是西北地区一个非常重要的铁铜矿床,对其地质特征及成矿模式的研究,将会对研究该成矿带铁铜矿床的成矿模式具有深远意义。通过大量的工作,认为桦树沟铁铜矿床为产于长城系上岩组的一套陆源碎屑岩夹碳酸沉积建造的同生海底喷流沉积矿床。铁矿体控矿构造主要是区域褶皱带,主要赋存于长城系上岩组的含铁细碎屑—粘土岩建造中,具体岩性为千枚岩。铜矿体的产出明显受后期韧性剪切带和层间滑动带共同控制,主要矿石类型有含铁碧玉岩型和蚀变千枚岩型两种。  相似文献   

中朝边境天池破火山口湖底地形多波束测深探测   总被引：4，自引：3，他引：1  

杨清福  原晓军  武成智  盘晓东  张羽 《岩石学报》2018,34(1):185-193

为调查天池破火山口湖的基本参数和湖底地形特征,研究破火山口的内部构造、破火山口的组合样式和垮塌堆积分布,本文采用多波束测深方法,对天池湖底地形进行了探测。探测结果显示:天池最大水深值为373.2m,天池水域边界实测周长为13.44km,天池湖水面面积9.4km~2,天池总蓄水量约为19.88×10~8m~3。天池周边分布4个温泉,温度为7~47℃。根据湖底地形推断,现今的天池破火山口形成于千年大喷发。其后,在天池西侧形成一个喷火口,东侧形成一个熔岩丘。天池湖底存在5个较大的破火山口内壁垮塌堆积区,但在湖底未见熔岩流。天池边缘出露的温泉点对应环状断裂,同时反映深部存在岩浆体。  相似文献