Method for calculating non-point source pollution distribution in plain rivers

The land area in a river network is divided into certain-scale square cells for the sake of precision, and, based on the physical mechanisms of rainfall-runoff processes and runoff pollution, the non-point source pollution from cells is estimated using the export coefficients of different land use types. The non-point source pollution from a land cell should all go into the closest fiver reach, so it is distributed according to the terrain of the plain river network area and the positions of land cells and river network reaches. A relationship between a single land cell and its pollution-receiving reach can be determined using this system. In view of the above, a spatial distribution model of the rainfall runoff and non-point source pollution in reaches of a plain river network area was established. This model can provide technological support for further research on the dynamic effects of non-point source pollution on water quality.

Late Quaternary diatom and sea level changes in estuarine plain of the Jiulong River

Four units and twenty-four zones of diatom have been discerned in the Borehole ZK5 in the estuarine plain of the Jiulong River, Fujian Province. Comprehensive analysis of these, together with microbiological assemblages and age determinations in some other boreholes, shows that during the Late Wurm Glacial, sea level of the study area rose and fell frequently, but had principally been in the environments of estuary-bay. This mainly resulted from the tectonic subouction. In this period 3 low sea levels occurred. at 18, 16 and 12 kaBP respectively. During Holocene, sea weter intruded massively and the sea level over the transgnaion maximum had been 5-10 m higher than that of the present.

Analysis on hydrochemical characteristics of groundwater in strongly exploited area in Hutuo River Plain

The Hutuo River alluvial-proluvial fan is located in North China Plain, and groundwater is the main source of water supply for agriculture and domestic water. Shijiazhuang depression funnels due to the long-term excessive exploitation are the bottleneck of the regional economic development. Analyzing the chemical characteristics of groundwater under the condition of strong human activities, can provide a scientific basis for further study of strong groundwater mining area environmental change. 143 groups of shallow groundwater samples are collected during the period of 2007-2008. In this paper, the hydrochemical characteristics of groundwater in the Hutuo River Plain area are analyzed systematically, using hydrogeochemical theory, combined with statistical methods and hydrochemical methods. Results are shown as follows: HCO_3^- and Ca^(2+) are major anion and cation. The variation coefficients of K^+, Ca^(2+), Mg^(2+) and HCO_3^- between 0.25 and 0.52, which means small and stable relatively. The variation coefficient of are Na^+, NO_3^-, Cl-, SO2-4 were large(0.89-1.01). They are sensitive and vulnerable to environmental change affect. Due to the impact of human activities, from the top to the edge of the alluvial-proluvial fan, the hydrochemical types of groundwater change from single to multiple, followed by HCO_3^-Ca·Mg, HCO_3·SO_4-Ca·Mg, HCO_3·SO_4·Cl-Ca·Mg, HCO_3·Cl-Ca·Mg and other types.

Assessment of shallow groundwater vulnerability in Dahei River Plain based on AHP and DRASTIC

Based on the special hydrogeological conditions of the Dahei River Plain in the Inner Mongolia area, assessment of shallow groundwater vulnerability is conducted based on DRASTIC model. Each evaluation indicator weight is determined by using analytic hierarchy process(AHP). The most important indicators are lithology in soil media and vadose zone. Assessment model of shallow groundwater vulnerability of the Dahei River plain is constructed. Distribution map of vulnerability index in this area is made with the spatial analysis function of ARCGIS. The results show that the particularly sensitive area is the piedmont of the Daqing Mountain, where the upstream place of the groundwater and the south-central place of the plain has the lowest vulnerability. The assessment results are more in accordance with the actual vulnerability conditions of this area by using analytic hierarchy process, and is helpful for groundwater protection.

Assessing Biogeomorphological State of the Teesta River Flood Plain: A Study on Gangachara Upazila, Rangpur, Bangladesh

Teesta river flood plain is one of the most significant landscapes in Bangladesh. The main theme of this research was to assess the present biogeomorphological state (biomass, herbaceous vegetation species, density of all vegetation species, flood plain extension mapping) of Teesta river flood plain under Gangachara upazila. The research work was conducted based on the objectives to prepare a map of Teesta river flood plain extension area, to estimate herbaceous vegetation (biomass, species types), and to find out the vegetation density to assess the present biogeomorphological state of study area. To present the flood plain area of Teesta river in the Gangachara upazila, base map has been used;herbaceous vegetation samples have been collected through quadrat method to estimate biomass (both in dry and before dry condition) using digital weight machine;vegetation density has been shown through NDVI of satellite image (Landsat-8) using red and NIR band in ArcGIS 10.1 software. From the results of this research, river flood plain area is found 68.5 sq. km;total 31 types of herbaceous species have been identified where Pouzolzia indica is the most dominated species covering 11.59% of the total area;maximum DNs value of NDVI is found +0.475242 which represents the highest vegetation density covering an area of 78 sq. km of the total area. The research may assist for the further study of river flood plain biogeomorphology throughout the country as well as in the world.

Geomorphological Evolution and Fluvial System Development during the Holocene: The Case of Vouraikos River Evolution in Kalavrita Plain, Northern Peloponnese, Greece

Fluvial geomorphology is affected by physical conditions which allow its adaptation due to high dynamics and environmental influences. Fluvial morphological changes are manifested as a result of tendency of the river system to maintain its physical balance. Our study area is the upper and middle flow part of Vouraikos river and surrounding area, near the NW border of Chelmos mountain in Northern Peloponnese, near the town of Kalavrita, at an altitude of 800 m. The area is part of the Skepasto basin, constituting of a graben with a general E-W direction that was developed NW of Kalavrita. The area comprises of Mesozoic, Upper Triassic-Jurassic limestone and dolomite of the Tripolitsa unit External Hellenides and Plio-Pleistocene fluvio-lacustrine sequences, while its tectonic structure is characterized mainly by normal faults. The geomorphological landscape is characterized by alluvial deposits and important geomorphological features including fluvial terraces, alluvial fans, fluvial scarps and their main rill washes. This area has been a place of major human activity as shown by the findings of many uncovered artifacts and a settlement. Through a paleographic reconstruction, detailed field investigations, in combination with the compilation of geomorphological maps using GIS software and archaeological evidence found in the area, we attempted to reconstruct the fluvial evolution of Vouraikos river and identify the major geomorphological factors that led to, and influenced it. Finally, the link between cultural activities and sedimentary processes is also studied. The recorded environmental variations had a great impact on the geomorphological shaping and instability of Kalavrita plain and Vouraikos river and are being reflected on the buried settlement. Sediment fluxes were high enough to form strath terraces, while local tectonics aided in the strath and fill terrace creation. Smaller and younger strath terraces, formed during increased sediment supply periods, when the valley was at a higher level.

Application of River Network Hydrodynamic Model in Determining Water Distribution Scale of Haishu Plain

The water distribution network is an important part of the plain water environment improvement system. To make efficient use of the regional water diversion source, scientifically distribute the water diversion flow and improve the water environment carrying capacity of Haishu Plain, the river network hydrodynamic model is used in this paper to simulate the water intake location, reasonable water quantity and influence range of water transfer in Haishu Plain. The simulation results have high accuracy, which can provide a scientific basis for the scale, water transfer mechanism and project layout of water transfer construction in Haishu Plain and show a strong reference value for the study of water diversion and distribution scheme of coastal plain river network.

Study on Spatial Variability of Soil Infiltration Coefficient in the Plain of the Yili River Valley in Xinjiang

22 typical test points and 8 profiles were selected and arranged in the plain of Yili River Valley based on lithological distribution and sedimentary characteristics to study spatial variability of soil infiltration coefficient. The results show that the infiltration coefficient of different geo-morphic units is as follows: the desert area > the pre-mountain alluvial-proluvial plain > river terrace,which is mainly related to the lithology of aeration zone,buried depth of groundwater and underlying surface. For the infiltration coefficient of different aeration zone mediums,the results are consistent with the changing law. The partition of plain of the Yili River Valley is based on geo-morphic units,infiltration coefficient and the lithology of aeration zone. The maximum infiltration coefficient is concentrated in the desert area,and there is zonal distribution of infiltration coefficient in plane.

A PRELIMINARY STUDY OF THE YELLOW RIVER'S PALEOCHANNELS IN NORTH SHANDONG PLAIN

According to buried depth, the Yellow Rver's Paleochannels can be divided into ground Paleochannels (buried depth 0-8m) and shallowburied Paleochannels theried depth 8-50m). Each of them can be roughly divided into three major Paleochannel belts, stretching Parallel with each other from SW to NE. Sedimentary layers of the paleochannels were mainly made up by sand levee of meanders or natural leavee deposits, and the flooding sedments were found bebeen the layers. The paleochannels in North Shadong Plain were formed in three stags; stage I (buried depth 50-15m) in later period of late Pleistocene-early period of Holocene, stag II (20-8m) in earlymiddle period of HOlocene; and stag III (8-0m) in midddle-late period of Holocene.

基于MIKE HYDRO River模型的轨交交通施工期防汛安全影响论证

轨交交通施工期间,受车站结构设计、周边场地限制等因素影响,河道需要断流施工,断流会对区域的防洪除涝安全及水环境产生影响。本文以上海轨道交通13号线西延伸工程为例,构建一维河网水动力模型,分析排涝及引调水工况下水位及水质变化情况。结果表明,平原河网地区个别河道断流对于区域防洪除涝安全影响较小,会严重影响河道断流处的水环境;通过增设导流措施可以减轻断流的影响,为平原河网地区河道断流影响分析及措施制定提供依据。

Fuzzy Synthetic Evaluation of Water Quality of Naoli River Using Parameter Correlation Analysis

In order to improve the effectiveness of Fuzzy Synthetic Evaluation (FSE) models, a Parameter Correlation Analysis (PCA) was introduced into the FSE and a case study was carried out in the Naoli River in the Sanjiang Plain, Northeast China. The basic principle of the PCA is that the pairs of parameters which are highly correlated and linear with each other would contribute the same information to an assessment and one of them should be eliminated. The method of the PCA is that a correlation relationship among candidate parameters is examined before the FSE. If there is an apparent nonlinear or curvilinear relationship between two parameters, then both will be retained; if the correlation is significant (p<0.01), and the scatter plot suggests a linear relationship, then one of them will be deleted. However, which one will be deleted? For solving this problem, a sensitivity test was conducted and the higher sensitivity parameters remained. The results indicate that the original data should be preprocessed through the PCA for redundancy and variability. The study shows that introducing the PCA into the FSE can simplify the FSE calculation process greatly, while the results have not been changed much.

Late Quaternary fluvial terrace formation in the Luan River drainage basin,north China and its possible linkages with climate change and tectonic activation

The Luan River is the most important water system in north-eastern Hebei Province,China and is located in the transitional zone of the Eastern Yan Mountains,North China Plain and Songliao Plain.The well-developed river terraces of its tributary,the Yixun River,provide excellent information for studying neotectonics and climate change.There are seven terraces in the lower reaches of the Yixun River,numbered T7-T1.The optically stimulated luminescence dating results of 23 samples show that terraces T7-T2 formed at 111.36±5.83 ka,78.20±4.45 ka,65.29±4.15 ka,56.44±3.07 ka,40.08±2.66 ka,and 13.14±0.76 ka,respectively.A comparison with the oxygen isotope curves of deep-sea sediments reveals that the sediment formation of each terrace corresponded to cold periods of marine isotope stages MIS 4 and MIS 2 and the relatively cold periods of MIS 5e,MIS 3,and MIS 1.Since the Late Pleistocene,the incision rate of the Yixun River has ranged from 0.371-1.740 mm/a.During the formation of T7-T6,T5-T4,T4-T3,and T3-T2,the incision rate was low.However,in the two stages during which T6-T5 and T2-T1 formed(13.14±0.76 ka to 0.58±0.08 ka and 10.79±0.64 ka to 0.16±0.01 ka),these rates reached 1.554 mm/a and 1.592-1.740 mm/a,respectively.At approximately 30 ka,the activity of the Langying Fault increased,leading to footwall uplift.The river gathered in the north of Langying to form the ancient Erdaowan Lake,which resulted in the drying of the river in the lower reaches of the Yixun River during the last glacial maximum without forming river deposits.In the Early Holocene,headward erosion in the lower reaches of the Yixun River was enhanced,which resulted in the disappearance of the lake,and incised meandering formed due to increased neotectonism.Based on the analyses of river incision and the formation of ancient lakes and incised meandering,it was inferred that there have been three periods of strong tectonism in the river basin since the Late Pleistocene.

Morphometric Assessment of Meandering River in Arid Region Using Improvement Model (Case Study: Maroon River)

To understand the natural environments of drylands, deserts, arid and semi-arid regions of the earth is to understand the processes and forms of their rivers. One of the river studies and fluvial processes are morphometry analyses. The channel forms in an alluvial plain reflecting the movement of water and the particle size of the load flowing down the channel. The dynamics of channel change has led to conflict with human resource development. Three basic channel patterns are detected in the region. They are braided, meandering and straight. In this research for assessment of meandering Maroon River, we used DEM (Digital Elevation System), Topography maps, Arc GIS software, Google earth, field work and library studies and mathematic formula. The two general indices for analyzing meandering patterns are 1) sinuosity coefficient 2) central angle. In this paper, the authors were used these factors and improved them. One of the results is creation of direction index and the second result is the Maroon River which has a type of sinuosity in any reach.

Water level updating model for flow calculation of river networks

Complex water movement and insufficient observation stations are the unfavorable factors in improving the accuracy of flow calculation of river networks. A water level updating model for river networks was set up based on a three-step method at key nodes, and model correction values were collected from gauge stations. To improve the accuracy of water level and discharge forecasts for the entire network, the discrete coefficients of the Saint-Venant equations for river sections were regarded as the media carrying the correction values from observation locations to other cross-sections of the river network system. To examine the applicability, the updating model was applied to flow calculation of an ideal river network and the Chengtong section of the Yangtze River. Comparison of the forecast results with the observed data demonstrates that this updating model can improve the forecast accuracy in both ideal and real river networks.

Downstream Decreasing Channel Capacity of a Monsoon-dominated Bengal Basin River: A Case Study of Dwarkeswar River, Eastern India

Downstream changes in channel morphology and flow over the ephemeral Dwarkeswar River in the western part of the Bengal Basin, eastren India were investigated. The river stretches from the Proterozoic Granite Gneiss Complex to the recent Holocene alluvium, forming three distinctive geomorphological regions across the river basin: the pediplane and upper and lower alluvial areas. Sixty cross-sections from throughout the main trunk stream were surveyed and the bankfull width, depth, cross-sectional area, and maximum depth were measured. Sediment samples from each location were studied and the flow velocity, stream power, Manning’s roughness coefficient, and shear stress were estimated. The results show that the bankfull channel cross-section area, width, width-to-depth ratio, and channel capacity increased between the beginning and middle of the river. Thereafter, the size of the river started to decrease in the lower alluvial area. This was characterized by gentle gradients, cohesive bank materials with grass cover, and channel switching. Within the lower part of the river, the channel capacity was observed to diminish as the drainage area increased. This increased the bankfull flow frequency and accelerated large floodwater losses in the floodplain via overbank flows and floodways.

Snake River: A Navigation and Spawning Dilemma

The Snake River in northwestern United States is 1735 km long, the largest tributary of the Columbia River and is the 13th longest river in the United States. The Snake River drainage basin includes parts of six U.S. states. The Snake River Plain was created by a volcanic hotspot that lies beneath Yellow-stone National Park. The previous Ice Age carved out canyons, cliffs and waterfalls along the middle and lower Snake River. The Missoula Flood was to the north and Bonneville Flood to the south altered the Snake River and surrounding landscape. The Snake River has a drainage basin of 282,000 km2 in the states of Oregon, Washington, Utah, Nevada and Idaho. The Snake River drops from mountain elevations of 3000 m to its confluence with the Columbia River. The river is one of the most biologically diverse freshwater systems in the United States with trails designed to promote recreational tourism, increase use of the Snake River and create generations of people who care about the river and are willing to protect and provide environmental stewardship of the river watershed resources.

基于河网水动力模型的水系连通性对水环境质量的影响分析研究

平原河网地区地势平坦流速较缓,水体抗污染能力弱,改善水系连通性对水环境质量提升至关重要。以水系连通性较差的盛泽镇跃进联圩为研究对象,通过开展引调水试验,构建圩区河网水动力模型,探索圩区水利工作调度运行规则、河网水系连通方法以及相应的水环境变化规律。研究以水龄作为水系连通性的一种时间尺度参量,建立了跃进联圩水动力-水质-水龄的河网水环境模型,模拟了5种引调水方案下,圩内水系连通性及水质改善情况,并构建了压力、状态与响应的引调水连通效果评估体系,实现了对水系连通性变化与水环境改善水平的定量分析。结果表明:从水体交换时长来看,研究区域主要河道水体交换时间在5天以内,水体连通性越好的河道,水龄越短;从水质指标变化来看,调水实验中圩内的水环境氨氮变化最为明显,对引调水响应度高,模拟结果显示水龄与氨氮浓度变化趋势基本一致,水体连通性越好,水龄越短,有利于氨氮的削减;从引调水方案来看,单一调度方式对圩内水系连通性改善能力有限,特别是在河网内水体流动性弱的区域,同时使得圩区内水体流动性差异增大,更容易造成河网内水系连通性以及水质的空间分布差异,形成局部的滞水区或死水区。因此,采用多源引水与多区域排水相配合的调度方式,可以加强水系连通性,改善水环境质量。

鄂尔多斯盆地大牛地气田二叠系山西组砂体叠置模式及油气开发意义

河流相砂体储层构型对致密砂岩中相对优质储层的分布规律和天然气开发具有重要意义。通过野外地质剖面和钻井岩心观察,结合测井、录井和岩心分析测试资料,对鄂尔多斯盆地大牛地气田大12井区二叠系山西组致密砂岩的砂体构型要素、叠置模式及油气开发意义进行了研究。研究结果表明:(1)鄂尔多斯盆地大牛地气田大12井区二叠系山西组发育六级复合辫流带和五级单一辫流带,其中单一辫流带包括河床(分流河道)和河漫共2个四级构型单元,河道内单个心滩沉积包含有三级增生体和落淤层;(2)辫状河三角洲平原五级单一辫流带中的四级泛滥平原沉积较辫状河河漫沉积更加发育,辫状河心滩沉积中落淤层欠发育;(3)山西组上部山2-2亚段辫状河单一辫流带内砂体呈“河道-心滩”连续沉积,泥质不发育,砂体叠置程度高(多呈复合式叠置)、连通性好,优质储层多;(4)山西组中下部山1段和山2-1亚段三角洲平原沉积中,西部河道连片性好,砂体以复合式和侧拼式叠置样式为主,连通性和生产效果均较好,东部砂体多为孤立式和侧接式,砂体钻遇率低,单井产量差。

西辽河平原浅层地下水中“三氮”分布特征及健康风险评价

通过测试地下水样品中“三氮”含量,采用非致癌风险评价模型进行健康风险评价.结果表明,与《地下水质量标准》(GB14848-2017)限值对比,硝酸盐氮超标率8%,主要分布在研究区东南部及西南部区域;氨氮超标率10%,主要分布在中部及南部区域.地下水中Ⅰ、Ⅱ、Ⅲ类水质占比83%;Ⅳ及Ⅴ类水水质占比17%.地下水样品中“三氮”总非致癌风险指数及总致癌性风险指数均低于美国环境保护署推荐的健康风险评价标准.整体上研究区“三氮”污染程度相对较轻,“三氮”污染区域主要分布于人类活动密集地区.健康风险评价可为地区地下水中“三氮”污染监控和治理提供技术参考.