鄱阳湖未控区间流域水量平衡分析及校验

针对鄱阳湖未控区间多年存在的水量不平衡现象,计算了鄱阳湖未控区间流域水量平衡的各水文要素,分析了形成水量不平衡的原因,采用水量平衡方法对实测的湖口站日平均流量过程进行了修正,并运用多输入单输出系统模型对修正后的结果进行了验证。结果表明,湖口站修正后的日流量过程合理可靠,能反映实际情况。

分布式水文模型构建及在黄河区间流域的应用

选择位于黄河支流洛河中游的长水—宜阳区间流域作为研究对象,基于数字高程模型,计算栅格水流方向、集水面积和栅格演算次序,为产汇流计算打下基础。把1个栅格单元作为1个小子流域,基于栅格采用新安江模型进行产流计算,采用Muskingum-Cunge算法进行河道洪水演算。结果表明,基于DEM的分布式水文模型在洪峰误差控制和过程拟合等方面表现较好,洪水模拟具有较高的精度。

水文倒推法在区间流域枯季径流模拟中的应用

为探究基于水量平衡的水文倒推法应用于区间流域径流预报的适用性问题,基于水文倒推法建立了枯季区间径流模拟方程,研究了金沙江中游金江街—攀枝花区间流域2004-2008年的枯季径流情况。结果表明,径流过程模拟效果较好,模拟峰值精度符合要求,与传统区间流域枯季径流预报方法相比,该方法计算简单,预报精度较高。

基于频率组合的区间流域设计洪水计算方法

从上下游断面洪水频率组合计算的角度,提出一种计算区间流域设计洪水的新方法。以清江水布垭-隔河岩区间流域(水-隔区间)为例,采用统计参数法、离散求和法、基于Copula函数的概率组合法(Copula-PC法)和基于Copula函数的蒙特卡罗法(Copula-MC法),分别推求水-隔区间最大3d洪量的频率曲线及设计值,并与传统方法进行比较。结果表明,频率组合思路合理可行,统计参数法和离散求和法计算的结果系统偏小,会低估下游断面的防洪风险,频率组合计算时推荐采用Copula-PC法和Copula-MC法。

分布式VIC水文模型在鄱阳湖未控区间流域模拟应用

本文利用土地利用数据和土壤类型资料,分别建立了流域植被网格参数库和土壤网格参数库,构建了鄱阳湖未控区间流域5 km ×5 km网格分布式VIC水文模型,并提出了水文参数网格化方法。应用结果表明,分布式流域模型的模拟结果略优于集总式水文模型,能较好地模拟区域径流过程和水资源量。在更精细的地形、土壤、植被数据支持下,分布式VIC模型的应用效果会有提升空间。本研究首次把分布式VIC水文模型应用于鄱阳湖未控区间流域,对于湖区等无资料地区的水文模拟分析提供了参考和有效途径。

三峡区间流域TMPA 3B43V7卫星降水产品多时空尺度精度评估

卫星降水产品属于间接估测降水,需要进行精度评估、适用性分析才能使用。利用地面站点观测数据评估了三峡区间流域TMPA 3B43V7卫星降水产品的年、月时间尺度及格点、流域空间尺度下的精度。结果表明,TMPA 3B43V7降水产品在月尺度上精度较高,在年尺度上数据精度稍差,但具有应用在降水变化特征分析、流域水文过程模拟等领域的潜力。

基于PSO的新安江模型对资水流域柘桃区间洪水预报研究

无资料地区的洪水预报研究是当前水文研究的热点内容。资水流域柘桃区间是湖南省三大暴雨中心之一,产生的洪水占整个资水流域近60%。柘桃区间受客观条件限制无实测洪水资料,基于区间实测降水量数据,构建基于粒子群参数优化算法(PSO)的新安江三水源模型进行洪水预报,提高预报精度并计算此地区设计洪水保障防洪安全。结果表明:22场实测洪水率定和10场实测洪水验证的洪水预报精度均较高,基于PSO优化算法的新安江模型模拟效果较优;随着重现期增大,考虑柘桃区间与上游柘溪水库的最不利洪水组合,得到的资水流域控制站桃江站设计洪峰大于站点实测洪水计算得到的设计洪峰。研究结果可为资水流域柘桃区间梯级电站合理调度提供方案设计依据,为资水下游防洪安全和发电效益提供技术支持。

2021年秋汛期三门峡水库潼三区间来水量研究

2021年黄河发生1949年以来最严重秋汛,三门峡水库在此次秋汛防洪调度中发挥了重要的作用。由于潼关至三门峡区间(潼三区间)缺乏水文监测,因此在2021年秋汛期以潼关站计算的入库水量与实际水量相差10.4亿m^(3),对区间来水考虑不足影响了三门峡水库的精准调度。从库区区间来水分析着手,以潼三区间为研究对象,根据数字高程模型、土地利用类型、土壤类型、气象水文等数据,建立了HEC-HMS分布式水文模型,选取包括2021年秋汛在内的11场实测洪水资料进行率定和验证。结果表明,11场洪水模拟洪峰流量误差均小于20.0%,平均确定性系数为0.725,模拟合格率为90.9%,较准确地模拟了2021年秋汛期潼三区间来水过程,并量化了不同支流对区间来水总量的贡献率。

资水流域柘桃区间设计暴雨时空分布分析

【目的】通过研究资水流域暴雨中心柘桃区间设计暴雨的时空分布规律,为柘桃区间流域梯级水库洪水预报和防洪调度优化提供科学依据。【方法】以柘桃区间17个雨量站近30 a不同历时的年最大暴雨为研究数据,进行站点和面暴雨频率分析计算;采用不同历时降雨强度-历时-频率曲线和设计暴雨空间分布变化特征,分析雨量站网的设计暴雨时空分布规律。【结果】柘桃区间雨量站网设计暴雨的时空分布极不均匀,短历时内设计暴雨强度增幅较大;在空间分布上,随着重现期的增长,设计暴雨中心位置从资水流域中游扩大到下游;随着设计暴雨历时的增长,暴雨中心范围逐渐变小。【结论】柘桃区间雨量站点设计暴雨具有短历时内暴雨强度增速快、中游设计暴雨较大的特点,研究结果可为资水柘溪以下流域重要城市的防洪安全提供理论依据。

仿生算法优化BP神经网络在降雨空间插值中的应用

人工神经网络能够充分挖掘已知样本中的规律,从而对未观测数据进行预测,可应用于降雨量空间插值计算中。在BP神经网络进行降雨空间插值的基础上,引入遗传、粒子群和蚁群3种仿生算法对BP神经网络初始权值和阈值进行优化,将优化后的BP神经网络应用于三峡区间流域年、月和日3个时间尺度的降雨空间插值中。结果表明:仿生算法对BP神经网络初始权值和阈值优化求解后,降低了BP神经网络陷入局部最小以及过拟合的风险,在插值过程中表现出较好的稳定性,取得了理想的插值结果。

三峡蓄水后城陵矶-武汉河段泥沙粒径变化分析

利用长江中游城陵矾一武汉河段的3个主要控制水文站（城陵矾、螺山、汉口）近10a的实测悬移质颗粒级配资料，采用方差分析及Wilcoxon加符秩检验两种统计方法，对该河段河流泥沙级配在三峡工程蓄水运用前后的变化进行了分析。结果表明：在三峡工程蓄水运用后，螺山和汉口站控制的区间流域河流泥沙粒径有明显粗化现象，粒径范围为0．0620．500mm，而整个城汉河段河流泥沙粒径并没有显著变化。

建立多支流汇入河段洪水预报模型的方法

针对受无流量控制断面支流汇入影响的河段,传统预报方法很难较好预报洪水过程的实际情况,以实例流域数据和实时水情传输系统为基础,将水文预报数学拟合模型进行了尝试性应用。

黄河流域内蒙古区间降雨径流模拟及水量平衡分析

以黄河内蒙古流域为研究区,利用GIS/RS技术获取流域水循环空间分布信息,选取黄河上游石嘴山、中游万家寨水文站为研究区的入、出站,利用近30年的降水等气象资料和近10年的水文资料,构建了基于SWAT(Soil and Water Assessment Tool)分布式水文模型的黄河流域内蒙古区间的降雨径流模型。通过对模型的校准、验证,初步分析了该区间降水与径流量的关系及水量平衡。结果表明:黄河流域内蒙古区间农用灌溉、池塘蓄水等人为因素对径流量的影响要大于气候变化对其的影响;且在干旱的气候条件下,降水少,蒸散发量较大,从年尺度上看,通过降雨形成的径流量是非常有限的。构建的模型基本能够反映黄河流域内蒙古的月径流水文过程,水量平衡分析也揭示了当地干旱气候下径流的特征。

Snowline and Snow Cover Monitoring at High Spatial Resolution in a Mountainous River Basin Based on a Timelapse Camera at a Daily Scale

Snowline change and snow cover distribution patterns are still poorly understood in steep alpine basins of the Qilian Mountainous region because fast changes in snow cover cannot be observed by current sensing methods due to their short time scale. To address this issue of daily snowline and snow cover observations, a ground- based EOS 7D camera and four infrared digital hunting video cameras （LTL5210A） were installed around the Hulugou river basin （HRB） in the Qilian Mountains along northeastern margin of the Tibetan Plateau （38°15′54″N, 99°52′53″E） in September 2011. Pictures taken with the EOS 7D camera were georeferenced and the data from four LIL521oA cameras and snow depth sensors were used to assist snow cover estimation. The results showed that the time-lapse photography can be very useful and precise for monitoring snowline and snow cover in mountainous regions. The snowline and snow cover evolution at this basin can be precisely captured at daily scale. In HRB snow cover is mainly established after October, and the maximum snow cover appeared during February and March. The consistent rise of the snowline and decrease in snow cover appeared after middle part of March. This melt process is strongly associated with air temperature increase.

Spatial distribution,sources and ecological risk assessment of heavy metals in Shenjia River watershed of the Three Gorges Reservoir Area

Surface soil/sediment samples were collected from the Water-Level Fluctuation Zone(WLFZ), cultivated land and forest land at 50 different grid points from Shenjia watershed, the Three Gorges Reservoir area in August 2013. The spatial distribution, sources and ecological risk assessment for Arsenic(As), Cadmium(Cd),Chromium(Cr), Copper(Cu), Nickel(Ni), Lead(Pb)and Zinc(Zn) were analyzed in this study. The results showed all tested metals had similar distribution patterns except Ni and Cr, with areas of high concentrations distributed in the southwest(WLFZ and watershed outlet) of the study area. Ni and Cr,which were highly positively correlated and present in high concentrations, were primarily distributed in the south and middle zones of the study area. Lower concentration areas of all metals were uniformly distributed west of the high-elevation zones and forest land. Factor analysis(FA) and factor analysismultiple linear regression(FA-MLR) showed that the major sources of Cd were fertilizer and traffic sources,which together accounted for 87% of Cd. As, Zn and Cu levels were primarily supplied by industrial and domestic sources, accounting for 76% of As, 75% of Cu and 67% of Zn. Surface soils/sediments of the study watershed contaminated by Cd represent a high ecological risk, whereas other metals represent low ecological risks. The potential ecological risk index(PERI) analysis indicated that it had a low(widerange) ecological risk and a moderate(small-range)ecological risk primarily distributed in the outlet of the study watershed. Fertilizers and traffic are the primary sources of Cd pollution, which should be more closely controlled for the purposes of water quality and ecological conservation.

Trend in Observed and Projected Maximum and Minimum Temperature over N-W Himalayan Basin

Recently, study in past trends of climate variables gained significant consideration because of its contribution in adaptions and mitigation strategies for potential future changes in climate, primarily in the area of water resource management. Future interannual and inter-seasonal variations in maximum and minimum temperature may bring significant changes in hydrological systems and affect regional water resources. The present study has been performed to observe past(1970-2010) as well as future(2011-2100)spatial and temporal variability in temperature(maximum and minimum) over selected stations of Sutlej basin located in North-Western Himalayan region in India. The generation of future time series of temperature data at different stations is done using statistical downscaling technique. The nonparametric test methods, modified Mann-Kendall test and Cumulative Sum chart are used for detecting monotonic trend and sequential shift in time series of maximum and minimum temperature. Sen's slope estimator test is used to detect the magnitude of change over a period of time on annual and seasonal basis. The cooling experienced in annual TMax and TMin at Kasol in past(1970-2010) would be replaced by warming in future as increasing trends are detected in TMax during 2020 s and 2050 s and in TMin during 2020 s, 2050 s and 2080 s under A1 B and A2 scenarios. Similar results of warming are also predicted at Sunnifor annual TMin in future under both scenarios which witnessed cooling during 1970-2010. The rise in TMin at Rampur is predicted to be continued in future as increasing trends are obtained under both the scenarios. Seasonal trend analysis reveals large variability in trends of TMax and TMin over these stations for the future periods.

Wet-Dry Runoff Correlation in Western Route of South-to-North Water Diversion Project,China

The Western Route of the South-to-North Water Diversion Project is an important trans-basin diversion project to transfer water from the upstream Yangtze River and its tributaries （water-exporting area）, to the upstream of the Yellow River （water- importing area）. The long-term hydrologieal data from 14 stream gauging stations in the Western Route area and techniques including the pre-whitening approach, non-parametric test, Bayes, law, variance analysis extrapolation, and Wavelet Analysis are applied to identify the streamflow eharacteristics and trends, streamflow time series cross-correlations, wetness-dryness encountering probability, and periodicities that occurred over the last 50 years. The results show that the water-exporting area, water- importing area, and the streteh downstream of the water-exporting have synehronization in high-low flow relationship, whereas they display non- synchronization in long-term evolution. This corresponds to the complicated and variable climate of the plateau region. There is no obvious increasing or decreasing trend in runoff at any gauging station. The best hydrological eompensation probability for rivers where water is diverted is about 25% to lO%, and those rivers influenced significantly by diversion are the Jinsha and Yalong rivers. Proper planning and design of compensation reservoirs for the water-exporting area and stretch downstream of the water- exporting area can increase the hydrological compensation possibility from water-exporting area to the water-importing area, and reduce the impact on the stretch of river downstream of the water- exporting area.

An adaptive smoothed particle hydrodynamics for metal cutting simulation

Normally large amounts of particles are required to accurately simulate the metal cutting process,which consumes a lot of computing time and storage.Adaptive techniques can help decrease the number of particles,hence reducing the runtime.This paper presents a novel adaptive smoothed particle hydrodynamics(SPH)method for the metal cutting simulation.The spatial resolution changes adaptively according to the distance to the tool tip by the particle splitting and merging.More particles are selected in the region where the workpiece and the tool are in contact.Since the contact region constantly changes during the cutting process,two quadrilateral frames are adopted in the adaptive algorithm to dynamically change the distribution of particles.One frame for the refinement,the other for the coarsening.These frames move at the same speed as the tool.To test the computational efficiency,the metal cutting process is simulated by using SPH with three different adaptive approaches.Numerical results show that the proposed adaptive algorithm with dynamic refinement and coarsening can significantly optimize the runtime.