We build copula function-based joint distribution models for the annual maximum flood peaks of the Yangtze River and Poyang Lake, to analyze the coincidence probabilities, using scenarios that combine with the impoundment of three Gorges, define influencing indexes and relative contribution rates on flood coincidence at varying frequencies. The study shows the probabilities for coincidence of floods with 1000, 100, and 10-year return periods in both Yangtze main stem and Poyang Lake are respectively 0.02, 0.19 and 2.87%, with higher coincidence probabilities for shorter return periods; when 1000-year flood occurs in the Yangtze, the probabilities for Poyang Lake to encounter flood of the 1000, 100, or 10-year magnitude are higher than 16.08, 42.48 or 74.77% respectively; Poyang–Yangtze flood coincidence is affected by operation of the hydraulic engineering. The lowering of flood peaks caused by the Three Gorges impoundment and regulation of the lake have respectively reduced the probabilities of Poyang–Yangtze flood coincidence by about 7.0 and 1.97%, with average relative contribution rates − 33.82 and − 17.1%; influenced by hydrological projects in Poyang basin, variations in Poyang’s inflow flood have displayed an average contribution rate of 20.4% for the negative effect on extreme (P < 5% or P > 90%) flood coincidence, while having a positive contribution rate of 38.2% on floods of other return periods. The results can help increase our understanding of flood coincidence, and support flood control efforts in Poyang Lake; its analytical approach may also be useful to other applications of copula functions.

Single scouring as well as channel geometry adjustments takes place in the long distance downstream of dams for a long term because of the huge loss of sediment load.Using field data,we take the typical continuous bends from Xiantao to Xiao Chenjiatai in the Hanjiang River downstream of Danjiangkou Reservoir as a case to study the single scouring and channel geometry charactreistics.The results show that this reach is currently experiencing severely scouring and then the thalweg scours lower and the deep channel extends to be wider and longer.In addition,riverbed incision is the main pattern and lateral erosion is limited for the protected banks in this reach.In the bend,shoals in the convex are retreating generally.The convex shoals in the bends with less radious present alternative deposition-erosion pattern while convex shoals in the slight-curved bends show unidirectional retreating.Chute cutoff phenomenon reveals the results of discharge increase in the middle-dry season in meandering reaches downstream of dams.

In Yangtze river basin,the interaction of mid-lower stream of river and lake is becoming increasingly complex nowadays because the dam construction and the reservoir operation upstream are changing the natural coming water condition.Based on the water exchange process analysis of Yangtze River and Poyang lake in which the Poyang lake diverts flood from Yangtze river in flood season and replenishes water in dry season,three indexes are defined to quantify the water exchange characterization and monthly variation of the Yangtze River and Poyang Lake,i.e.,the index of jacking strength (JSI),the index of intruding strength (ISI) and the coefficient of water exchange (WEC).The method of trend-free pre-whitening Mann-Kendall (TFPW-MK) is employed to analysis the trend of annual water exchange as well as the Mann-Kendall (MK) method.The regime of river-lake water interaction are revealed in perspectives of the difference of coming water,the operation of the Three Gorges reservoir and the stage-capacity variation of Poyang lake.Results show that the flood from Yangtze River diverting to Poyang Lake is the major state during flood season (July to September),the annual mean JSI is 27.5％ with a frequently intruding phenomenon (the average ISI is 8.3％);the water from Poyang lake flowing into Yangtze River is the major state during non-flood season (December to April) with the annual mean JSI 8.8％.After the Three Gorges being put into operation since 2003,the flow of mid-lower Yangtze River increased during the period of December to March with a JSI enlarged by 6％ at Hukou station;the peak clipping effect of the Three Gorges in the flood season weakened the jacking strength and intruding strength by 4.8％ and 2.3％,respectively.Also the average annual JSI is further deceased 0.14％ due to the capacity evolution of the Poyang Lake in the past 20years.The differences of coming water from Yangtze River and Poyang Lake is the dominant factor which drives the evolution of river-lake interaction.This research explored the water exchange regime of Yangtze River and Poyang Lake which could be used as a reference for the comprehensive management of Poyang Lake.

结合海绵城市实施的基本理念,明确低影响开发海绵城市所涉及的水文循环过程,指出城市雨水径流量计算是重要的前提条件.传统的市政排水设计多应用于不透水地面比例较大的城镇化地区,仅能提供最大雨水流量,暴雨强度公式和径流系数尚存在一定的优化空间,不能完全满足海绵城市规划设计诉求.水利行业常用推理公式、瞬时单位线、水文模型等水文学方法计算小流域设计洪水,通过暴雨、产流、汇流等过程,能准确描述不同控制点的雨水径流过程和积水量,有助于确定蓄存和排泄水量,是海绵城市设计和实施的关键环节,水文分析计算的方法适应性更强,值得进一步推广应用.

Hydrologic regulation is an important ecosystem service, and is easily influenced by human disturbance. Many studies have been conducted on the impacts that human activities have on flow regime and regulating capacity by a single environmental factor. However, these studies have not clarified the comprehensive effects at sub-watershed scale; these effects are important for sub-watershed management. This research was conducted to reveal the spatial heterogeneity of hydrologic regulating service and identify the impact factors in China's Yangtze River Basin. This basin is the largest in China and frequently floods. We built a new index based on the coefficients of variation for precipitation and runoff. The proposed indicator reflected the relative strength of regulating service effectively, and distinguished the basin into two different groups (A and B) of sub-watersheds. The hydrologic regulating index was significantly and positively correlated to slope and coverage of bush and forest, and negatively correlated to hydraulic projects, farmland, and urban area. Land-use changes have the greatest contribution (more than 60%) to differences in sub-watershed hydrologic regulating service. Compared with the sub-watersheds of group A, the sub-watersheds of group B suffered more severe human activity, for which the relative contributions to hydrologic regulating service were 32.18% (hydraulic projects), 18.21% (farmland) and 6.21% (urban area). These results indicated that the ecological effects of human activities should be a concern, and that restoration of the natural environment should play an important role for hydrologic regulating capacity enhancement. Group A sub-watersheds should explore the existing massive potential of (cascade) reservoirs for improving hydrologic regulating ability. Our results not only present a useful tool for watershed hydrologic regulating assessment, but lay a foundation for exploring differentiated management strategies of flood mitigation at sub-watershed scale.

This study investigates the urbanization of Taihu Basin and its influence on Satellite Pour l'Observation de la Terre (SPOT)-Normalized Difference Vegetation Index (NDVI). The correction model of the Defense Meteorological Satellite Program-Operational Linescan System (DMSP-OLS) of nighttime images was built to extract the dynamics of urban expansion. Tempo-spatial correlations between a vegetation index and nighttime light intensity are discussed to quantitatively assess the urbanization effect. The results show that Taihu Basin is in a period of rapid urbanization. Urban expansion is developing not only surrounding the city center circle but also along the main traffic arteries and rivers, which show a linear expansion resulting in an urban agglomeration. Under the influence of urbanization, the NDVI shows a slight decrease, and there is a significant negative tempo-spatial correlation in the urban areas of the eastern watershed between NDVI and nighttime light intensity, which are predominantly the low vegetation abundant areas. The contribution of urbanization to NDVI is negative in the eastern region. The contribution rates are greater than 14.0% and, in some cases, exceed 30%. This paper indicates the urbanization characteristics and their effect on the surface vegetation in Taihu Basin. In addition, based on the calibration model, the DMSP-OLS nighttime light data have a strong ability to examine the spatiotemporal evolution of urbanization. The results can provide support for the study of urban hydrology.

Based on the precipitation data of 21 meteorological stations in Poyang Lake basin, the temporal and spatial variability of seasonal precipitation was analyzed by wavelet analysis method. This study adopted the cross wavelet transform to analyze the correlation between the seasonal precipitation and climate indices in time and frequency scales, discussed the possible links between its precipitation variations and climate indices, and preliminarily analyzed its mechanism and regular pattern of variation. The results showed that the oscillations in 2–4 years' and 4–8 years' bands were the main variation periods of seasonal precipitation in Poyang Lake basin. In the 2–4 years' band, the years of rainfall peaks appearing in Poyang Lake were basically consistent with the years when El Niño appeared, and the precipitation oscillations in summer appeared more dramatic in space. According to analysis on the cross wavelet power spectra between different seasonal rainfalls and climate indices, certain correlations between climate factors and seasonal precipitation had existed in specific time periods. Large-scale climate oscillations like the El Niño/Southern Oscillation, North Atlantic Oscillation, Indian Ocean Dipole, and Pacific Decadal Oscillation caused the variability of large-scale circulations through their respective independent or inter-coupled climate systems, and affected the precipitation distribution in Poyang Lake basin by changing local climate conditions like the East Asian Monsoon.

Danjiangkou Reservoir ( DKJR) is the water source area of the Middle Route of South-to-North Water Diversion Pro-ject, and it is very important to investigate the variation trend of natural inflowrunoff of DJKR. Compared to the natural inflowrunoffseriesbetween1956and1998(short series),theaverageannualinflowrunoffbetween1956and2012(longseries) de-creasedby1.34%,andthedeviationofaverageinflowwasbetween6%~ 8% inMarch,April,andMayandbelow4% forother months, which indicated that the short inflowrunoff series adopted by the design of DJKR is good and representative.The dif-ferent statistical analyses showed that inflowrunoff has significant decreasing trend in April and May,but no apparent trend in other months.The wavelet transformation and moving average analysis results indicated that the annual inflowrunoff has the 23-year and 9-year periodic variation regularities.Moreover, the continuous decreasing of inflowrunoff froM1990s to 2002 re-flected the dry period in the variation between the wet and dry periods.

In this article, the error amplification matrix is developed for the SIMPLE algorithm formulated on the nonorthogonal grid by Fourier decomposition. The effect of grid skewness on the convergence properties of the SIMPLE algorithm is investigated in terms of robustness and convergence rate. As the grid nonorthogonality increases, the robustness of the SIMPLE algorithm, characterized by the convergence range of the pressure relaxation factor for a given velocity relaxation factor, weakens, and an effective remedy is to take the cross pressure correction terms into account rather than omit them, which is in agreement with the conclusions reached by Peric. In the case of convergence, the convergence rate seems to be strongly dependent on flow field, and the optimal rate can be reached when the grid direction coincides well with the local flow direction. The analysis also suggests that a collocated layout should be adopted in preference to a staggered layout, due to its better robustness on a nonorthogonal grid.

Under the influence of natural evolution of rivers and lakes and human activity, the measured data of controlling sta-tion at outlet of Poyang Lake ( Hukou Hydrological Station) can not meet the demand of consistency and reliability. Moreover, the water regime of the lake area is complicated and the measured date is scare, so the design flood calculation is difficult. There-fore, on the basis of reservoir flood theory, the calculation method of total inflow was introduced. For the runoff of the hydrologi-cal station at tributaries and in the area lack of controlling station, only the propagation time superposition was considered, so as to avoid the influential factors. The calculation result can reflect the actual flood magnitude and temporal-spatial distributions, and it fulfills the demand of flood calculation standard.

Taking the most strict water resources management in Hanjiang River Basin as the background ,Based on crucial control sections (including important cities ,provincial boundary cross sections ,ecological control section and the water conservancy project sections) ,this study establishes a water resources allocation simulation model in Hanjiang River basin after generalizing the basin in-to 28 subareas .The impacts of three water transfer projects including the Han Ji-Wei Project ,Middle Line South-to-North Project and Yangtze River to Hanjiang Project on the allocation results are discussed .

水资源承载力作为评价地区水资源安全与否的一个基本度量,其理论与应用研究意义重大.根据DPSIR框架展开水资源承载力因子分析,得到一个4层递阶结构的指标初选框架,并构建了一套全面的水资源承载力指标体系.以汉江流域为例,采用层次分析-模糊综合评价法(AHP-Fuzzy)展开水资源承载力评价与预测.分析结果表明:不调水情况下,江汉流域3级分区中,丹江口以上分区水资源承载力优于其他2分区;实施调水后,各分区水资源承载力受跨流域调水的影响而发生变化,均可认为已达到基本可承载状态.

针对平原感潮区内地势平坦、河涌密布、洪水受外江(海)潮水顶托的复杂排涝问题,研究了平原感潮区水闸和泵站联合运用的排涝分析步骤和计算方法,并将改进的平湖法应用于广州市典型感潮区的排涝分析计算中.结果表明,改进平湖法将河网概化为蓄水湖泊,并考虑了不恒定流水面曲线的变化规律,可作为平原感潮区排涝规划和排涝工程设计的参考.

In order to coordinate the role of reservoirs in water resources development and river ecosystem protection,a scheme for designing ecological storages were presented and applied on Danjiangkou reservoir.Tennant Method was used to calculate reference values of ecological flow in Xiangyang and Xiantao,two control sections downstream of Danjiangkou reservoir.Then an optimization model for ecological storage were established based on an integrated consideration of the reservoir’s multi-function,including flood control,ecological water demand,water supply,water transfer,power generation and navigation.Finally,solutions were obtained by integrating Adaptive Genetic Algorithm(AGA) with scheduling simulation technology under the background of four operation rules respectively.Results indicated that the operation charts with ecological storages could meet the demand of ecological flow in the control sections with a superior comprehensive benefit.In addition,optimize-simulate technology was approved to be a viable approach for the ecological storage design.

南河流域洪水特性受台风雨影响,表现为洪高量大,汇流快.为了对三里坪枢纽工程验收提供设计洪水复核成果,通过对坝址附近控制站—台口(二)水文站多年实测资料分析,并进行历史洪水调查,结合历史洪水与实测洪水组成不连续系列进行频率分析,得出坝址设计洪水成果,对原有初步设计成果加以复核.复核结论认为,依据台口(二)站计算的设计洪水成果可作为三里坪水库的设计依据.其分析计算方法可供类似工程区域设计洪水计算参考.

Rather than optimizing water regimes for one or a few species, a better approach is to approximate the natural flow regime that maintains the entire panoply of species. RVA method generally describes flow regimes with 32 hydrologic indicators, and quantifies passing-dam changes in these indicators. Based on this observation, an ecological goal is established to consider natural river flow regimes in this paper. By the membership of river environment in the goal set, the membership function or the optimization goal is determined by using fuzziology. This model is applied to the Xiangyang cross section downstream the Danjiangkou reservoir, maximizing the membership of indicators for maintaining the natural flow regime. Calculations show that the maximum membership is 0.5 or that the optimum release after regulation is 50% degree close to the natural flow regime. Then a traditional regulation model of power generation is developed to analyze environment sound degree and power generation. The results indicate that the ecological model is better in improving river ecosystem, but it reduces power generation to some extent. And a win-win between ecosystem and power generation is also possible by optimizing regulation.

To solve the problems of errors increasing with the extension of the forecast cycle and inadequate protection against random factor interference when using the existing models for multi-cycle urban water demand forecast,an equidimensional information renewal radial basis function neural network model was proposed,and the clustering approach was used for system learning.This model was applied to the annual water demand forecast in Dongguan City.The results show that the model has higher forecast accuracy than the fundamental radial basis function neural network model,and its forecast errors do not increase with the extension of the forecast cycle.