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Yang X.,Nanjing University of Information Science and Technology | Yang X.,Hohai University | Wang G.,Nanjing University of Information Science and Technology | Ye J.,Huaihe River Basin Meteorological Center | Li Y.,Hohai University
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

Terrestrial evapotranspiration (ET) connects land water cycle with land energy cycle. Analysis of the spatio-temporal of ET in Huai River basin helps us understand the response of water cycle in Chinese climate transition zone to global climate change and provide some valuable information for prediction of the change of water resource in that region in the future. Based on water balance model in Huai River basin, this study validated the accuracy and applicability of ET data from Global Land-surface Evaporation: the Amsterdam Methodology (GLEAM) using hydrological data. In addition, we also analyzed the interannual spatio-temporal variation of yearly and seasonal ET and the annual cycle of the monthly and daily ET in the Huai River basin during the period from 1980 to 2011 using GLEAM ET data. Results showed that: 1) Compared to the observed precipitation, the precipitation estimated by GLEAM ET data had lower mean relative error (MRE 8.0%) and the high correlation coefficient (0.94); The GLEAM data showed a high capacity of reflecting the magnitudes and spatial pattern of basin-scale ET in Huai River basin; 2) The mean annual ET of Huai River basin was 673 mm during the period of 1980-2011; 3) GLEAM model showed that the spatial variation of mean annual ET value ranged from 528 to 848 mm during the period from January 1, 1980 to December 31, 2011 over Huai River basin, which had a significant difference in spatial patterns; GLEAM model also showed that spatial patterns of mean annual ET decreased from the southwest to the northeast part of Huai River basin and that the mean annual ET in the southern region of Huai River was greater than in the northern region of Huai River; The mean seasonal ET had similar spatial pattern with the mean annual ET using the GLEAM ET data over the Huai River basin; 4) the domain-averaged annual ET in Huai River basin varied from 588.6 to 767.8 mm and showed a prominent increasing tendency for the period of 1980-2011; The GLEAM ET data showed a strong seasonality of ET in Huai River basin with the maxima in August and the minima in December; Among four seasons, the summer ET was the largest with the value of 272.0 mm, followed by the spring(191.4 mm) and autumn (144.3 mm); The smallest value was 65.0 mm in winter; 5) Spatial distribution of annual change rate of ET during 1980 to 2011 in Huai River basin every 10 years based on grid scale for all of Huai River basin was dominated by the change rate of ET in spring, followed by that in summer and autumn. The effect of ET changing rate in winter on annual ET was quite weak. Annual ET in most area over Huai River basin had an increasing tendency. Overall, this study can provide valuble information for monitoring and forecasting extreme hydrometeorological events, such as flood and drought. It also can provide decision-making reference for water resource management in Huai River basin. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved.

Chen Y.-D.,Nanjing University of Information Science and Technology | Min J.-Z.,Nanjing University of Information Science and Technology | Gao Y.-F.,Nanjing University of Information Science and Technology | Gao Y.-F.,Huaihe River Basin Meteorological Center
Shuikexue Jinzhan/Advances in Water Science | Year: 2011

Based on the unstructured meshes and uses finite volume method, an adjoint model of data assimilation is established to study the variation of Bottom Friction Coefficients (BFCs) in tidal bore affected estuaries and to inversely estimate the spatial and temporal variation of BFCs during flood or ebb tide. A series of twin experiments on the BFCs were carried out in a generalized estuary. The experiment indicates that the existence of large spatial variation in BFCs will have a negative effect on the inversed result. The result can be improved with the increase in assimilated observations. The adjoint model is tested using the observed data in the Qiantang Estuary. The derived BFCs during the flood and ebb tide are 0.000149 and 0.001520 (equivalent to 0.012206 and 0.038987 of Manning coefficients), respectively. Both deformation of tidal waves and occurrence of tide bores are successfully simulated using the inversed values of BFCs. The result reconfirms the previous findings that the BFCs during the flood are smaller than that during the ebb in the Qiantang Estuary.

Shao Y.,Nanjing University of Information Science and Technology | Wu J.,Nanjing University of Information Science and Technology | Ye J.,Huaihe River Basin Meteorological Center | Liu Y.,Henan Polytechnic University
Theoretical and Applied Climatology | Year: 2015

This study investigates frequency analysis and its spatiotemporal characteristics of precipitation extremes based on annual maximum of daily precipitation (AMP) data of 753 observation stations in China during the period 1951–2010. Several statistical methods including L-moments, Mann-Kendall test (MK test), Student’s t test (t test) and analysis of variance (F-test) are used to study different statistical properties related to frequency and spatiotemporal characteristics of precipitation extremes. The results indicate that the AMP series of most sites have no linear trends at 90 % confidence level, but there is a distinctive decrease trend in Beijing-Tianjin-Tangshan region. The analysis of abrupt changes shows that there are no significant changes in most sites, and no distinctive regional patterns within the mutation sites either. An important innovation different from the previous studies is the shift in the mean and the variance which are also studied in this paper in order to further analyze the changes of strong and weak precipitation extreme events. The shift analysis shows that we should pay more attention to the drought in North China and to the flood control and drought in South China, especially to those regions that have no clear trend and have a significant shift in the variance. More important, this study conducts the comprehensive analysis of a complete set of quantile estimates and its spatiotemporal characteristic in China. Spatial distribution of quantile estimation based on the AMP series demonstrated that the values gradually increased from the Northwest to the Southeast with the increment of duration and return period, while the increasing rate of estimation is smooth in the arid and semiarid region and is rapid in humid region. Frequency estimates of 50-year return period are in agreement with the maximum observations of AMP series in the most stations, which can provide more quantitative and scientific basis for decision making. © 2015, Springer-Verlag Wien.

Ye J.-Y.,Hohai University | Ye J.-Y.,Huaihe River Basin Meteorological Center | Huang Y.,Nanjing University of Information Science and Technology | Li Z.-J.,Hohai University | Yu Z.-B.,Hohai University
Journal of Hydrologic Engineering | Year: 2013

A prompt availability of precipitation intensity is crucial for accurate and effective flood forecast. When radars are coordinated, the mosaic of weather radar can perform rainfall estimation over large areas. This study presents an experimental method of rainfall estimation based on multiple-Doppler radars over the Huaihe River Basin in China. The method emphasizes the combined use of six radars in the area. The processes reviewed are base-data collection, conversion from radar reflectivity to rain rate, rain gauge calibration, consensus of rainfall, and rainfall mosaics. A case study of an extreme meteorological and hydrological event, which occurred in July 2007 over the Huaihe River basin in China, was examined, and the estimated error of rainfall is lower than 45% after calibration with measurements from rain gauges. The results show that the proposed rainfall estimation method presents a cumulative rainfall distribution that is similar to the observations. It is both practical and reliable for the Huaihe River Basin. © 2013 American Society of Civil Engineers.

Ye J.,Hohai University | Ye J.,Huaihe River Basin Meteorological Center | Li Z.,Hohai University | Wu Y.,Hohai University
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2013

For flash flood warning in ungauged basins, this paper proposes an approach that uses an antecedent precipitation index method and a Nash model for runoff forecasting. To estimate the parameters n and k of this model, we established a mathematical relationship between these parameters and the topographic attributes derived from DEM using the software ArcGIS. This approach was tested by simulations of ten flood events in a case study of the Dasha River basin. The results show that the qualified simulations of both runoff volume and flood peak discharge account for 80%. The approach does not need mass rainfall-runoff data and it is very useful for flash flood warning in ungauged basins. © Copyright.

Ye J.,Hohai University | Ye J.,Huaihe River Basin Meteorological Center | Wu Y.,Shandong Electrical Power Engineering Consulting Institute Corporation | Li Z.,Hohai University | Chang L.,Hohai University
Journal of Hohai University | Year: 2012

Two methods were adopted in this study to forecast flash floods in medium and small rivers in humid regions: the Xin'anjiang model was applied to areas with sufficient historical data, and the API-Nash model, in which the rainfall-runoff relationship method is used for runoff yield forecasting and the Nash runoff model is used for flow concentration forecasting, was applied to ungaged areas or data-deficient regions. A case study was conducted in the Tunxi Watershed in the mountainous area of southern Anhui Province, using the two models to simulate flood processes in the watershed. The results show that both models had favorable simulation results. They presented similar accuracy in calculating the qualified rate of the flood volume, and the Xin'anjiang model had higher accuracy than the API-Nash model in calculating the qualified rate of the flow peak and the deterministic coefficient.

Ye J.,Hohai University | Ye J.,Huaihe River Basin Meteorological Center | Yao C.,Hohai University | Li J.,Hydrological Bureau of Anhui Province | Li Z.,Hohai University
Journal of Hohai University | Year: 2013

A single objective function with consideration of multiple factors was established using the SCE-UA algorithm and the comprehensive error coefficient method, and was applied to parameter calibration in the Xin'anjiang model. A case study was conducted in the Luxi Basin, which is located in the southern mountainous area of Anhui Province. The daily runoff process and hourly flood process in this basin were simulated, and reasonable results were obtained. The research results show that, by considering multiple precision evaluation indices in the objective function, the simulation results of the Xin'anjiang model are optimal. In this case, the hydrological processes can be accurately simulated.

Wang H.,Huaihe River Basin Meteorological Center | Luo J.,Huaihe River Basin Meteorological Center | Ye J.,Huaihe River Basin Meteorological Center | Ye J.,Hohai University | Li Z.,Hohai University
Journal of Hohai University | Year: 2014

Based on the CMORPH-Gauge merged data and observed rain gauge data, the daily area rainfall of 15 sub-catchments in the Huaihe River Basin was calculated during flood seasons (June to September) from 2008 to 2011, using the Thiessen polygon method and the grid arithmetic average method. Comparative statistical analysis was conducted on the results of the two methods. The results show that the two sets of area rainfall of the 15 sub-catchments exhibited systematic differences and a significant linear correlation. The daily area rainfall also showed systematic difference. The area rainfall based on rain gauge data was generally greater than that based on the CMORPH-Gauge merged data. There was a strong correspondence for the magnitude between the two sets of area rainfall. The overall correspondence ratio was 78.8%, with the ratio of rainfall values that differed by an order of magnitude being 20.5%. The correspondence ratio for the light-rainfall magnitude reached 91.4%.

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