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新安江模型河网汇流参数Cs对洪峰模拟影响较大，目前Cs的确定需依赖于大量的历史数据，因此Cs的确定成为无资料地区和资料匮乏区水文模型应用中亟需解决的棘手问题.本文基于参数的物理意义，通过自相似河网结构的假定，构建Cs与河网形态、流域下垫面特征的相关联系，提出基于河链蓄量方程的Cs估算方法，对半干旱、半湿润和湿润地区等不同水文气象分区的11个流域的Cs值进行推算并代入新安江模型中进行模拟，经比较发现，11个流域子流域Cs计算均值与新安江模型率定结果相近，说明该Cs计算方法是合理的.选取陈河、屯溪两个典型流域研究单元流域属性对Cs的影响，由结果可以看出Cs与流域面积、河链数、河宽呈正相关，与单元流域距离出口的远近呈负相关，这表明流域分块后各单元流域Cs值不一致，而新安江模型中采用相同Cs值对不同单元进行调节必然会造成汇流计算的误差.为进一步提高该方法在无资料地区的应用效果，将新安江模型汇流模块修改为每个单元使用对应的Cs计算值进行滞后演算，以陈河和屯溪流域为例采用新安江模型Cs率定值、Cs计算均值以及修改后新安江模型3种不同方案进行模拟比较，从模拟结果可以得出，修改后的模型具有明显优势，将模型参数与下垫面条件建立了联系，模型物理机制提高且参数的独立性增强，对于新安江模型在无资料地区的应用具有重要的指导意义.

To ascertain characteristics of parameters of watershed runoff and converge and evolution mechanism of runoff changes,effects of watershed surface changes on flooding design have been analyzed. Land surface changes of Weihe watershed using Xin'anjiang-Haihe Model have been studied and the consistency of flood series was corrected using integrated linear weight method.The results indicated that the parameters of the free water storage capacity,the recession constant in the"lag and route"method,the interception and the retention capacity of surface runoff and the outflow initial depth of underground reservoir all increased and the underlying surface had obvious changes after 1980,resulting in the reduction of runoff in the watershed. Runoff depth modeling between Hehe watershed and Wuling watershed for 15 floods before 1980 and 32 floods after 1980 were all more than 80% accurate compared with the records in the datasets,reaching the accuracy of the second-best class in all the records. After the corrected-parameters,the modeling 5th largest flood has reduced 27. 1% errors,the 15 th largest flood reduced 25. 4% errors,and the 30 th largest flood reduced 23. 0% errors,compared with the previous modelings on average. The study provided a scientific basis for constructing the water projects,being safeguard of floods,and satisfying the demand of water supply for people's daily lives and industrial activities.

The Huaihe River basin is located in the transitional zone from north subtropical to south warm temperate climate.The characteristics and influential factors of precipitation in different fields are various.This study investigated the distribution and determined the influential factors of precipitation in flood season over the Huaihe River basin.For this goal,the meteorological observation data of 145 stations from 1961 to 2010 were collected and analyzed.The percent of different intensity rainfall days and the ratio between storm days and rainfall days were calculated.Finally,the temporal variations of meteorological observation data were analyzed.The results showed that rainfalls in the southern of Huaihe River basin are higher than those in the northern,affected by several factors,such as terrain,moisture and wind.Meanwhile,rainfall exhibited temporal characteristics,with the percent of storm cases and ratio of storms to rainfall increasing from 1961.This study derived two main conclusions: first,the precipitation of the Huaihe River basin became heterogeneous in spatial and temporal distribution with the changing of climate;second,the heavy rain cases such as storm occurred more frequently than before.

Coupling radar-rainfall data with distributedhydrological model was important in improving flood forecast precision and leading time.However,radar-rainfall error propagation inhydrological model largely affected runoff process simulation.In this study,the operational radar-rainfall data,provided by Huaihe River basin Meteorological Center,was analyzed.With HEC-HMShydrological model input,radar-rainfall data was used to simulate and analyze the runoff process of rainfall concentration period,in the Xixianhydrological station of Huaihe River basin,during July 1-10,2007.The results showed that runoff simulation based on radar-rainfall data was consistent with the simulation based on rain gauge data.The radar-rainfall input errorhad been decreased obviously after the propagation of the HEC-HMS model.Runoff simulation based on radar-rainfall data by union calibration was the best,whose relative error were-20.2% and-13.3% for flow process and peak flow,respectively.

The losses caused by flood disasters are becoming increasingly serious with the rapid development of social economy.As an important non-engineering flood protection measure,real-time flood forecasting plays an important role in flood control.Due to the severity of flood disasters and the complexity of flood routing process in the Huaihe River basin,the research on flood forecasting system has been a focus for a long period.A case study from Wangjiaba to Xiaoliuxiang section is discussed and a research on flood forecasting system is presented in this paper.On the basis of the hydrologic characteristics in the study area,this paper takes flood flow routing as mainline,uses the Xin'anjiang model for runoff yield prediction,generalizes flood diversion and retarding regions,applies hydrologic and hydraulic methods to simulate flow routing in the main channels,and fits stage-discharge relationships by multiple regression method.A general system is established by integrating the above parts and then by coupling K-Nearest Neighbor method to attach real-time correction to forecasting results for the real-time forecasting system.Inspected in 2003 and 2007,the system achieved high prediction accuracy,which proves that the system is sound and can be applied to this basin.

Since 1980s,with the increasing impacts of human activities on the river basin landscape,it is significant to investigate the impact of landscape changes on the rainfall-runoff regime.This paper simulated the floods occurred in the Zijingguan and Fuping catchments of the Haihe Basin using an empirical method.The flood data were segmented by time for creating the P+Pa-Rs curve to analyse the influence of the altered catchment landscapes on surface flow regime.Based on the unit hydrograph method,the relationship between the runoff R and peak discharge Qm was established.The results show that by comparison of the trendlines in different time periods,with the same runoff volume,the peak discharge after 1980s is less than that before 1980s.It indicates that the water regulation function of Haihe Basin was enhanced.Based on the relationship between the changes of runoff and peak discharge induced by the altered basin landscapes,it is found that there is a positive correlation between them.

Hydraulic model of Huaihe River with flood diversion and flood retarding areas was developed for flood forecast.The input flood discharge hydrograph from the main channel to the flood diversion area is estimated with the fixed split ratio of the main channel discharge.The Muskingum discharge routing method is applied in the flood diversion area,and outflow can generate only after it reaches full storage.The flood flow inside the flood retarding area is calculated as a reservoir and inflow and outflow are calculated based on the water balance equation.Taking complex river basin between Wangjiaba and Lutaizi stations with flood diversion and flood retarding areas of Huaihe River as an example,with taking the Linhuaigang Project as inside boundary in flood routing,Hydraulic model of Huaihe River based on one-dimension hydraulic model was developed.In order to testify the performance and rationality of the developed model,the representative flood events from 2003 to 2008 were forecasted with the developed hydraulic model.Results show that the developed model performs well and is reasonable.

In recent years,climate change and human activities have changed the hydrological characteristics of underlying surface.In this condition,it is of important theoretical and practical significance to study how the flood responds to the changes of land utility and cover.The flood level of Yi River,Henan Province is not high but it occurred with high frequency and has a negative effect on the reservoir and channel.If the flood volume turns small,the downstream flow of Yi River can also become small.Reservoir can control middling storage capacity for flood flow and be adjusted to the required storage and the opposite is also right.Therefore,it is necessary to do some research on the downstream of Yi river.The final simulation results by applying the HEC model show that the food volume and peak flow value decreased by 35.11% and 12.30% respectively from 1964 to 2000 in Dongwan Basin,upper reaches of Yi River.The effect of land-cover between current cover and past cover on hydrology would be small for large storm and big for small storm events.

TOPMODEL is a semi-distributed model in which the predominant factors determining the formation of runoff are represented by the topography of the basin. In this paper we dealed with DEM information of Buliu river basin, extracting drainage network, sub-basin area, topographic index and distribution of runoff distance, and applied TOPMODEL in the basin. For the sake of comparison, the Xin’anjiang model was also applied in the basin. Here we analyzed the difference of simulation function due to the frameworks of the two models. The simulation results of the two models have little difference; moreover TOPMODEL realized the visualization of spatial source area distribution.

Lake Nansihu is a complicated watershed.It is one of important regulation lakes for east route of Water Diversion Project from South to North.It is also the watershed of frequently occurrence of flooding and draught.At first,the distributed Xinanjiang model is calibrated for tributaries with the observed discharge data and the whole flood forecasting model is set up.The one and two dimension hydraulic models are coupled with hydrological model and used for the flood routing and flood regulation for upper lake of Lake Nansihu.