拉萨河流域河宽与地形结构因子相互关系分析

利用Google Earth遥感影像,测量了拉萨河流域451个局部河段的河流水面宽度,得出了10个主要河段的平均河宽。研究中,分别点绘了10个主要河段的平均河宽与5种地形结构因子(河流纵比降、弯曲度、凹度、河流上游集水面积、流域平均坡度)的相关图,采用线性函数、指数函数、对数函数以及幂函数4种函数对其进行相关性分析。结果发现,在5种因子中,河流水面宽度与上游集水面积相关性最好,当用线性函数拟合时确定性系数达到了0.81;河流的纵比降与河宽的相关性也较好,当采用指数函数与幂函数拟合时,两者的确定性系数均为0.76。研究探讨拉萨河流域河宽和地形结构因子的相互关系对认识青藏高原河流地貌特征规律以及提高无资料流域河流流量和总水量预测的能力等均有重要意义。     

基于DEM的河宽模型在山区中小流域内的构建与应用

合理可靠地估算河道栅格单元内的河道断面宽度是分布式水文模型汇流计算时的重点和难点问题。为此,研究提出一种适用于山区中小流域的河宽模型。该模型综合考虑了集水面积和地形对河流宽度的影响,利用DEM数据提取了河道上游集水面积和河道附近一定范围内的坡度,并建立起与河道断面宽度之间的函数关系,进而构建适用于不同流域的河宽模型。结果表明,在未明显受到水利工程影响的河段上,可以较为准确地估算出河道宽度的空间分布,刻画出自然条件下河道宽度从上游到下游震荡增大的变化特点;且基于不同分辨率的DEM数据构建的河宽模型均能取得较好的计算结果。     

河道形态改造对城市河流生态水力性能的影响

为探究城市河道形态改造的有效性,根据河道自然修复理念,采用正弦函数对典型城市渠化河道的河宽、水深和蜿蜒度等地形几何变量进行振荡波动,并借助数字河道合成技术生成6种河道数字地形模型,在此基础上采用二维水动力模型考察不同河道形态改造对河床干扰度、水力形态多样性指数和浅滩缓流生境面积等生态水力指标的影响。结果表明:研究河段城市渠化河道生态水力性能随地形几何变量的振荡波动而变化,且河道空间形态越复杂,河道生态水力性能越好；在高流量(8~12m³/s)下,“深潭-浅滩”形态构造下河床干扰度平均减少88.2%,水力形态多样性指数平均提高37.4%,而浅滩缓流生境面积增加24.9倍,表明河流生态水力性能得到显著改善；城市河道近自然形态重构能大幅降低河道对于流量变化的敏感性,并显著提高河道生态结构稳定性,有助于河流生态系统的恢复。     

二维非恒定流模型在大辽河河道现状行洪能力分析中的应用

对于水流形态复杂、河道弯曲的感潮河段,利用非结构网格,可较好地模拟出河道内的复杂地形,计算并分析河段的现状行洪能力。本文以大辽河为例,在建模过程中考虑上游不同河段来流与下游潮位的影响;使用河道实测横断面,参考设计资料,结合实际洪水确定计算模型参数。研究成果可为河流上游水库群调度提供决策支持。     

黄土丘陵沟壑区坡长与地形复杂度关系研究

流域分布式土壤侵蚀学坡长作为流域和区域尺度水文模型和土壤侵蚀模型的最基本参数之一,对研究土壤侵蚀的形成和发展有重要影响。从黄土丘陵沟壑区的常用地形因子入手,详细探讨了坡长与地形之间的联系,在此基础上建立了地形要素交互作用的多维复合集成模型,并根据该模型定量计算出研究区各地形要素对坡长的贡献,进而揭示了地形对于水土流失的影响。研究表明:①复杂地形因子对于坡长的贡献率更高,更能揭示地形对于水土流失的影响;②7种复合地形因子,对于坡长的贡献正负不一;③地形因子对坡长的贡献率由高到低依次为坡谱信息熵、粗糙度、高程面积积分、起伏度、海拔标准差、平均坡度、剖面曲率、平面曲率、沟壑密度。     

受亚布力水库工程影响尚志、一面坡、青云水文（位）站测站功能恢复方案

拟建的亚布力水库工程是在蚂蚁河流域上游的尚志、一面坡、青云水文（位）站测站监测流域面积内新建的蓄水工程。工程集水面积407 km2,占尚志水文站集水面积的16.3%,占一面坡水位站集水面积的17.4%,占青云水位站集水面积的30.5%。根据水文技术标准《水文站网规划技术导则》规定,为＂蓄水工程集水面积占水文测站集水面积比值在15%～50%,属受水工程中等影响程度,调整要求：作辅助观测及调查。＂。工程改变下游河道水文测站径流形成过程、流域水量时程时空分布,流域水量平衡。影响水文测站水文测验、水文情报预报、水文资料系列连续性、一致性、完整性。需根据《中华人民共和国水文条例》规定和水文技术标准规定针对工程影响采取相应补救措施。     

枕头坝—沙坪二级河段流量延时时间分析

研究区域选定为枕头坝一级电站下游至沙坪二级电站上游河段全长28 km的大渡河干流河段,由于研究区域现有的水文资料有限,沙坪二级电站缺乏入库流量监测设备,给水动力参数的演变规律研究带来了很大的困难.本研究根据实测的水位、流量、河道地形资料,使用HEC-RAS建立枕头坝一级水电站—沙坪二级水电站一维水动力模型,精细描述水流...     

基于SWAT模型的流域特征自动提取

流域特征获得是进行流域水文特性分析的主要前提之一。本文以牛栏江流域上游河段的德泽水库为例,采用DEM作为基础数据在SWAT模型的环境下实现流域河网及边界的自动提取。结果表明:在牛栏江流域上游河段利用SWAT模型提取的流域河网与实际地形图上绘制的河网基本吻合,根据河网共划分45个小流域,提取的流域集水面积与实际集水面积相对误差2%,由此说明利用该方法提取牛栏江流域上游段河网及边界的可行性。     

机载激光雷达在金沙江下游河道地形及断面测量中的应用

为解决水沙监测工作效率低、施测难度较大等问题,根据金沙江下游河道地形特点、水文泥沙观测精度要求,选择典型河段进行机载三维激光扫描技术和传统测绘技术手段地形测绘,对两种技术手段采集的成果数据进行精度统计、分析与评价。结果表明:在金沙江下游河道地形及断面测量中,机载激光雷达技术的平面精度和高程精度均能满足相关规范要求,可应用于金沙江下游梯级水电站地形和断面数据采集;但对植被密集树林地区,仍需要采用传统测绘技术方法进行补测。     

2021年十大孔兑区域土壤侵蚀空间分布特征

土壤侵蚀是内蒙古自治区十大孔兑区域最严重的环境问题之一。为该区域生态环境的健康发展，本研究基于多源数据结合多种土壤侵蚀模型对2021年十大孔兑区域的土壤侵蚀做出评估，评估结果显示：2021年十大孔兑区域土壤侵蚀面积为4398.85 km²，占区域总土地面积的40.86%，其中轻度、中度、强烈、极强烈和剧烈等级的土壤侵蚀面积分别为2614.38 km²、1328.74 km²、276.29 km²、194.45 km²和40.15 km²，区域整体以中度和轻度侵蚀为主。基于评估结果本研究总结了十大孔兑区域土壤侵蚀的空间分布特点，并综合多因素对侵蚀特征进行分析，最终得到如下结论：(1)十大孔兑区域的水力侵蚀离散分布于孔兑上游，这是由地形地貌、植被覆盖等多个因素共合同作用导致的，其中地形地貌对侵蚀分布的影响相对较大;(2)十大孔兑区域的风力侵蚀聚集分布于孔兑中下游，中游的库布齐沙漠是孔兑中风力侵蚀最为严重的区域，风力侵蚀的分布受到土地利用类型和植被覆盖的影响较大;(3)十大孔兑区域的土壤侵蚀集中在达拉特旗、东胜区和杭锦旗境内，但由于各县区部分覆盖的侵蚀地貌不同，各县区在水力和风力侵蚀面积占比上有很大差异。     

土地覆被和气候变化对拉萨河流域径流量的影响

以拉萨水文站上游流域为研究对象,利用分布式水文模型SWAT对拉萨河流域水文过程进行模拟,分别用1995～2000和2003～2006年两个时间段的实测数据对模型进行校准和验证。结果显示月径流模拟相关系数和模拟效率系数分别为0.88和0.84。在此基础上通过建立情景模拟,探讨拉萨河流域气候波动和土地覆被变化对径流产流量的影响。结果表明:气候变化对年径流量影响显著,在各种模拟假设情景中最多可以使径流量增加89%。土地覆被变化相对于气候变化对径流量的年际影响较弱,但对径流量的季节变化影响显著。     

Depositional settings of sand beaches along whitewater rivers

The numbers and sizes of sand beaches suitable for recreation along selected whitewater rivers in the western United States depend on sand concentrations, range of discharge and the size, frequency and type of depositional settings. River‐width expansions downstream from constrictions are the predominant depositional setting for sand beaches in the upper Grand Canyon and along five Wild and Scenic Rivers in Idaho, but not along other rivers. Beaches located upstream from constrictions are rare, in general, except in the Grand Canyon. Beaches found in expansions without constrictions dominate depositional sites along the Yampa and Green Rivers, are fairly common along the rivers in Idaho, but are relatively rare in the Grand Canyon. The magnitude of flow expansion is a reliable predictor of beach size. Beaches located on the inside of curves are uncommon, in general, but can be important recreation sites. The mid‐channel bar setting is the least important from a recreation standpoint because that setting is rare and beaches there are typically small, and emergent only at low flow. The frequency of beaches is highly variable among rivers and the concentration of sand in transport is only partially responsible. Of the rivers studied, the unregulated Yampa River carries the highest concentrations of suspended sand and has among the most beaches (1.2 beaches km^?1). Emergent sand beaches are essentially nonexistent along the Deschutes River and are rare along other Oregon rivers, yet these rivers transport some sand. Sand beaches are fairly common (0.8–1.1 beaches km^?1) along the regulated Colorado River, but are comparatively rare (0.6 beaches km^?1) along the unregulated Middle Fork Salmon River. The suspended sand concentrations in study reaches of these two rivers are similar, and the difference in the frequency of beaches may be largely because the processes that create beach‐deposition settings are less active along the Middle Fork Salmon. Published in 2008 by John Wiley & Sons, Ltd.     

小尺度山洪灾害区下垫面特征分析——以官山河流域为例韩

为响应国家加强小区域山洪灾害建设和防范预警要求,给小尺度山洪灾害区域建设和预警提供基础数据支撑,以官山河流域为例,采用地学统计、植被指数计算、面向对象与人机交互解译、空间叠加分析、野外调查等方法,获取流域地形、坡度、植被覆盖度、土地利用类型等下垫面特征,分析潜在受灾村落和人口。结果表明:官山河流域地势中间低、边缘高,最低点为流域出水口,平均历史受灾海拔、坡度分别为415 m和21°;平均植被覆盖度为71%,主要土地利用类型为林(草)地,历史受灾主要在低植被的沿河、沟、道路周边;居民房屋为山洪灾害重点承灾体,占总面积的1%,裸地、坡耕地占总面积的2%;潜在受灾房屋主要集中在官山河、袁家河、吕家河、西河两侧地势低的位置,受灾总人口为8 106人,2 023户。官山河流域出口处的弯曲、窄河段、上下游卡口区条件,不利于快速泄洪,易引发山洪灾害。在强降雨下,裸地、低植被陡坡地易产生山洪,沿河、道路周边低植被覆盖的村落易遭受山洪灾害。官山河流域共有12个村存在潜在受灾威胁,需做好山洪灾害预警和防范建设;五龙庄、大河湾、赵家坪、吕家河、马蹄山、西河、官亭村是山洪灾害防御建设的重点。     

水工程调度与低影响开发协同作用下典型城市片区洪涝过程模拟——以福州市为例

城市水工程调度与低影响开发措施，在应对城市暴雨洪涝中发挥了重要作用。本文以沿海城市福州主城区晋安河片区为例，构建一套综合的水文水动力模拟框架，从全域视角分析实时控制调度下的洪涝响应特征，并选择典型社区，从社区尺度下分析低影响开发措施与水工程调度协同作用下的洪涝过程。结果表明，全域尺度下，通过上游水工程联合调度可以有效控制下游内河水位，距离琴亭湖更近的晋安河主河道断面相比于下游断面，其断面水位变化受实时调度方案影响更为明显。在未考虑河道漫溢时，联合调度对河道水位的影响明显大于对内涝淹没的影响。在社区尺度下考虑河道漫溢时，低影响开发措施与水工程调度对内涝淹没的协同作用明显。在重现期为100 a、历时为2 h降雨下，协同治理前后，淹没面积由7.57 hm~2减少至4.85 hm~2;在苏迪罗台风降雨数据驱动时，协同治理前后，淹没面积由22.87 hm~2减少至9.83 hm~2。研究成果可以为城市防洪减灾应对措施提供一定的参考。     

Estimation of Potential Soil Erosion for River Perkerra Catchment in Kenya

River Perkerra catchment with an area of 1207 km² is drained by River Perkerra, which is one of the rivers flowing into Lake Baringo whose drainage area is 6820 km². The lake is in a semi-arid area of Kenya. Its depth has reduced from 8 m in 1972 to 2.5 m in 2003 due to siltation resulting from high erosion rates in the catchment. The entire catchment is characterised by very steep slopes on the hillsides and gentle slopes in the middle and lower reaches where the surface is bare with very little undergrowth. Interventions to control soil erosion in this fragile ecosystem have been limited partly because of lack of data on erosion and its spatial distribution. In the present study, Universal Soil Loss Equation (USLE) was used in conjunction with GIS Arc/Info and Integrated Land and Water Information Systems (ILWIS) to estimate potential soil loss from River Perkerra catchment. Various physical parameters of the equation were derived by analysing spatial data and processing Landsat TM satellite imagery of the catchment. The estimated potential soil erosion from the catchment was 1.73 million tonnes/year while the sediment yield at the catchment outlet was found to be 1.47 million tonnes/year. The sediment delivery ratio derived using an empirical equation was 0.83. This figure indicates that a higher proportion of sediments generated in the catchment is delivered at the outlet. The use of GIS enabled the results of erosion potential to be mapped back onto the catchment. This is useful in identifying priority areas that require urgent management interventions in controlling soil erosion.     

River Temperature Modelling by Strahler Order at the Regional Scale in the Loire River Basin,France

Daily water temperature was simulated at a regional scale during the summer period using a simplified model based on the equilibrium temperature concept. The factors considered were heat exchanges at the water/atmosphere interface and groundwater inputs. The selected study area was the Loire River basin (110 000 km²), which displays contrasted meteorological, hydrological and geomorphological features. To capture the intra‐basin variability of relevant physical factors driving the hydrological and thermal response of the system, the modelling approach combined a semi‐distributed hydrological model, simulating the daily discharge at the outlet of 68 subwatersheds (drainage area between 100 and 3700 km²), and a thermal model, simulating the average daily water temperature for each Strahler order in each subwatershed. Simulations at 67 measurement stations revealed a median root mean square error (RMSE) of 1.9°C in summer between 2000 and 2006. Water temperature at stations located more than 100 km from their headwater was adequately simulated (median RMSE < 1.5°C; ?0.5°C < median biases < 0.5°C). However, performance for rivers closer to their source varied because of the averaging of geomorphological and hydrological features across all the tributaries with the same Strahler order in a subwatershed, which tended to mask the specific features of the tributaries. In particular, this increased the difficulty of simulating the thermal response of groundwater‐fed rivers during the hot spells of 2003. This modelling by coupling subwatershed and Strahler order for temperature simulations is less time‐consuming and has proven to be extremely consistent for large rivers, where the addition of streambed inputs is adequate to describe the effect of groundwater inputs on their thermal regime. Copyright © 2015 John Wiley & Sons, Ltd.     

基于HI值的河流裂点与谷坡稳定性关系

为定量分析河流裂点对流域地质灾害分布的影响,基于面积-高程积分(HI)方法,利用ArcGIS和MatLab软件,首先计算了喜马拉雅山中部以及青衣江流域的HI值与崩塌滑坡密度之间的相关关系;然后以喜马拉雅山地区的雅鲁藏布江、印度河、波曲(Bhote Koshi河)、马甲藏布、朋曲(Arun河)和Kali Gandaki共6条河流为对象,分析不同河流裂点的成因;最后计算了所有河流裂点上、下游流域的HI值。所得结论如下:①流域HI值与崩塌滑坡密度存在良好的正相关关系,相关系数均＞0.5;②河流裂点上游流域的HI值均小于下游,说明上游流域的整体稳定性强于下游;③构造成因的河流裂点上、下游流域HI值差别较大(最小为0.06),而堵河成因的河流裂点上、下游流域HI值差别较小(最大为0.02)。研究成果为宏观定量判定山区谷坡稳定性提供了参考。     

萨克拉门托水文模型在天生桥洪水预报的应用

南盘江天生桥一级电站坝址以上流域位于云贵高原的东南斜坡，高原、丘陵、盆地错综其间，流域面积５０１３９，流域内岩溶较发育，洪水受溶洞、暗河的调蓄影响较严重，暴雨呈多中心分布，雨强分布不均，洪水过程以复峰矮胖型居多。因此，选用具有超渗和蓄满产流特性的萨克拉门托水文模型来建立天生桥一级电站入库洪水预报数学模型，比选用其它水文模型来进行洪水预报的效果更佳。     

Downstream channel changes after a small dam removal: Using aerial photos and measurement error for context; Calapooia River,Oregon

Dam removal is often implemented without adequate baseline monitoring to distinguish background variability from channel changes due to the removal. This study evaluated aerial photos as substitutes for multiple‐year pre‐removal field data to assess downstream channel changes associated with a small dam removal. The Brownsville Dam, a 2.1 m tall concrete dam on the Calapooia River, Oregon, was removed in 2007. We mapped bars and the low flow channel downstream from the dam and in an upstream control reach using aerial photos (1994–2008) and in the field prior to (2007) and following (2008) removal. The locations and magnitudes of changes in bar area and wetted width, relative to errors, indicate that downstream channel changes were a result of the removal. The maximum changes (?3520 ± 1460 m² for bar area, 32 ± 8 m for wetted width) observed prior to dam removal with aerial photos were far downstream. In contrast, the maximum changes after removal were immediately below the dam (200 ± 90 m² for bar area, ?11 ± 3 m for wetted width), and small in the upstream control (?150 ± 130 m² for bar area, 9 ± 4 m for wetted width). The dominant errors were photo specific: exposure error for spring to summer comparisons, position error for photos not processed for this study and identification error for small scale photos not scanned from film. We found aerial photos to be an acceptable but coarse substitute for multi‐year pre‐removal field data, and suggest best practices to minimize errors. Copyright © 2009 John Wiley & Sons, Ltd.