检索结果-南通市图书馆

Hydrological impacts of afforestation-A review of research in India

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2014年第1期25卷 37-42页

作者： B.Venkatesh N.Lakshman B.K.Purandara Regional Centre National Institute of Hydrology Department of applied Mechanics National Institute of Technology Karnataka

We review the current status of experimental studies in India to understand the linkages between afforestation and hydrology. This discipline deals with the use and management of water, social awareness of environmental problems, and ecosystem limitations on provision of watershed services by river basins in the mountain regions of India. Our review begins with examination of experimental works in tropical countries and proceeds to discussion of initiatives of Indian research institutes and Government organizations towards establishing experimental watersheds to understand the impacts of land cover changes on hydrologic regimes in the Indian sub-continent. This is followed by the review of the experimental work carried out by various authors to assess the impact of land cover changes on major water balance components such as, runoff, groundwater, evapotranspiration and sediment yield. The spatial scales of these experiments have been limited to small watersheds or field plots. This paper also describes impacts of human interventions （such as planta- tions of exotic forest species to restore degraded landscapes） on the water balance components in diverse hydro-geo-environmental conditions in the Indian sub-continent. We focus on identifying the research areas which require immediate attention to develop tools to assist planners and policy makers in assessing and managing the water resources in these complex environments. The review is largely based on research results reported during the last 20 to 30 years.

关键词： afforestation Western Ghats experimental watersheds land-use/cover changes humid tropics

KALMAN FILTERING CORRECTION IN REAL-TIME FORECASTING WITH HYDRODYNAMIC MODEL

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第3期20卷 391-397页

作者： WU Xiao-ling WANG Chuan-hai CHEN Xi XIANG Xiao-hua ZHOU Quan State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing210098 China Shanghai pudong area hydrology bureau Shanghai 201208 China

Accurate and reliable flood forecast is crucial for efficient real-time river management, including flood control, flood warning, reservoir operation and river regulation. In order to improve the estimate of the initial state of the forecasting system and to reduce the errors in the forecast period a data assimilation procedure was often need. The Kalman filter was proven to be an efficient method to adjust real-time flood series and improve the initial conditions before the forecast. A new model integrating the hydraulic model with the Kalman filter for real-time correction of flood forecast was developed and applied in the Three Gorges interzone of the Yangtze River. The method was calibrated and verified against the observed flood stage and discharge during Three Gorges Dam construction periods （2004）. The results demonstrate that the new model incorporates an accurate and fast updating technique can improve the reliability of the flood forecast.

关键词： real-time flood forecast Kalman filter hydraulic model alternate Kalman filtering method

A RIVER FLOW ROUTING MODEL BASED ON DIGITAL DRAINAGE NETWORK

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2005年第4期17卷 483-488页

作者： YUAN Fei REN Li-liang YU Zhong-bo XU Jing State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China

On the basis of Digital Elevation Model （DEM） data, watershed delineation and spatial topological relationship were proposed by the Digital Elevation Drainage Network Model （DEDNM） for the area upstream of the Hanzhong Hydrological Station in the Hanjiang River in China. Then, the Muskingum-Cunge method considering lateral flow into the river was applied to flood routing on the platform of digital basin derived from DEDNM. Because of considering lateral flow into the river, the Muskingum-Cunge method performs better than the Muskingum method in terms of the Nash-Sutcliffe model efficiency coefficient and the relative error of flood discharge peak value. With a routing-after-superposition algorithm, the Muskingum-Cunge method performs better than the Muskingum method in terms of the Nash-Sutcliffe model efficiency coefficient and the relative error of flood discharge peak value. As a result, the digital basin coupled with the Muskingum-Cunge method provides a better platform for water resources management and flood control.

关键词： Digital Elevation Model(DEM) digital basin drainage network flood river flow routing

Analytical solution for slope instability assessment considering impact of confined aquifer

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2015年第4期22卷 1502-1509页

作者：冉启华钱群王光谦傅旭东苏丹阳 Institute of hydrology and Water Resources Zhejiang University State Key laboratory of Hydroscience and Engineering Tsinghua University

An analytical approach was presented for estimating the factor of safety(FS) for slope failure, with consideration of the impact of a confined aquifer. An upward-moving wetting front from the confined water was assumed and the pore water pressure distribution was then estimated and used to obtain the analytical expression of FS. Then, the validation of the theoretical analysis was applied based on an actual case in Hong Kong. It is shown that the presence of a confined aquifer leads to a lower FS value, and the impact rate of hydrostatic pressure on FS increases as the confined water pressure increases, approaching to a maximum value determined by the ratio of water density to saturated soil density. It is also presented that the contribution of hydrostatic pressure and hydrodynamic pressure to the slope stability vary with the confined aquifer pressure.

关键词： confined/artesian groundwater slope stability factor of safety analytical approach

Incipient motion of sediment in presence of submerged flexible vegetation

在线全文

学校读者我要写书评

暂无评论

Water Science and Engineering 2015年第1期8卷 63-67页

作者： Hao Wang Hong-wu Tang Han-qing Zhao Xuan-yu Zhao Sheng-qi Lü State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University

The presence of submerged vegetation on river beds can change the water flow structure and alter the state of sediment motion. In this study, the incipient motion of sediment in the presence of submerged flexible vegetation in open channels was investigated in a laboratory experiment. The vegetation was simulated with flexible rubber cylinders arranged in parallel arrays. The effect of the vegetation density, water depth, and sediment grain size on the incipient motion was investigated. The experimental results indicate that the incipient motion velocity of sediment increases as the vegetation density decreases and the water depth and sediment grain size increase. With flexible plants, the incipient motion velocity of sediment is lower than it is without vegetation, and is larger than it is with rigid vegetation. A general incipient motion velocity equation was derived, which can be applied to both flexible and rigid vegetation conditions.

关键词： Sediment incipient motion Submerged flexible vegetation Open channel Experimentation Sediment grain size Water depth

Water level updating model for flow calculation of river networks

在线全文

学校读者我要写书评

暂无评论

Water Science and Engineering 2014年第1期7卷 60-69页

作者： Xiao-ling WU Xiao-hua XIANG Li LI Chuan-hai WANG College of hydrology and Water Resources Hohai University State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University Zhenjiang Engineering Survey and Design Institute Co. Ltd.

Complex water movement and insufficient observation stations are the unfavorable factors in improving the accuracy of flow calculation of river networks. A water level updating model for river networks was set up based on a three-step method at key nodes, and model correction values were collected from gauge stations. To improve the accuracy of water level and discharge forecasts for the entire network, the discrete coefficients of the Saint-Venant equations for river sections were regarded as the media carrying the correction values from observation locations to other cross-sections of the river network system. To examine the applicability, the updating model was applied to flow calculation of an ideal river network and the Chengtong section of the Yangtze River. Comparison of the forecast results with the observed data demonstrates that this updating model can improve the forecast accuracy in both ideal and real river networks.

关键词： plain river network cyclic looped channel network water level updating model hydrodynamic model, error correction

Effects of Coastline Changes on Tide System of Yellow Sea off Jiangsu Coast,China

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2009年第4期23卷 741-750页

作者：陈可锋王艳红陆培东郑金海 State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing Hydraulic Research Institute

On the basis of historical documents, this paper studies the evolutionary processes of the Jiangsu coast and re-estahhshes the positions of the shoreline in different periods. The East China Sea and the Yellow Sea mathematical models are applied to simulate and analyze the large-scale tidal waves changes under the influence of the coastal change in Jiangsu since 1855 when the Yellow River changed its lower course into the Bohai Sea. Results from this study can be summa- rized in the following aspects：（1） the coastline change strongly affects tidal waves in the region. Generally, the tidal amphtude decreases when the coastline changes in the north coast area of the abandoned Yellow River Delta, whilst increases in the south of this region. The maximum variation of tidal amphtude takes place near the Radial Sandbank. （2） Following the erosion of the abandoned Yellow River Delta in the past century, the non-tidal points of M2 and K1 partial tides move to southwest gradually. （3） During the early 20th century, with the coastline changing, tidal range decreased 30 - 60 cm. From the abandoned Yellow River mouth to the Lvsi Port, the maximum increase of tidal range can exceed nearly 150 cm. From the early 20th century to the early 21st century, the tidal range increases by 20- 50 cm outside the Radial Sandbank. Whereas, the tidal range reduced near the abandoned Yellow River mouth by 30 ~ 50 cm.

关键词： abandoned Yellow River Delta shoreline change numerical simulation the system of the Yellow Sea

A time-dependent numerical model of the mild-slope equation

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2007年第2期26卷 106-114页

作者： SONG Zhiyao ZHANG Honggui KONG Jun LI Ruijie ZHANG Wei State Key laboratory of hydrology - Water Resources and Hydraulic Engineering Ocean College Hohai University Nanjing 210098 China

On the basis of the previous studies, the simplest hyperbolic mild-slope equation has been gained and the linear time - dependent numerical model for the water wave propagation has been established combined with different boundary conditions. Through computing the effective surface displacement and transforming into the real transient wave motion, related wave factors will be calculated. Compared with Lin＇s model, analysis shows that calculation stability of the present model is enhanced efficiently, because the truncation errors of this model are only contributed by the dissipation terms, but those of Lin＇s model are induced by the convection terms, dissipation terms and source terms. The tests show that the present model succeeds the merit in Lin＇ s model and the computational program is simpler, the computational time is shorter, and the computational stability is enhanced efficiently. The present model has the capability of simulating transient wave motion by correctly predicting at the speed of wave propagation, which is important for the real - time forecast of the arrival time of surface waves generated in the deep sea. The model is validated against analytical solution for wave diffraction and experimental data for combined wave refraction and diffraction over a submerged elliptic shoal on a slope. Good agreements are obtained. The model can be applied to the theory research an d engineering applications about the wave propagation in a biggish area.

关键词： effective wave number effective surface displacement function numerical error stability analysis

Test of newly developed conceptual hydrological model for simulation of rain-on-snow events in forested watershed

在线全文

学校读者我要写书评

暂无评论

Water Science and Engineering 2013年第1期6卷 31-43页

作者： Si-min QU Han LIU Yan-ping CUI Peng SHI Wei-min BAO Zhong-bo YU State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University College of hydrology and Water Resources Hohai University Department of Forest Engineering Resources and ManagementOregon State UniversityCorvallisOR 97331USA

A conceptual hydrological model that links the Xin＇anjiang hydrological model and a physically based snow energy and mass balance model, described as the XINSNOBAL model, was developed in this study for simulating rain-on-snow events that commonly occur in the Pacific Northwest of the United States. The resultant model was applied to the Lookout Creek Watershed in the H. J. Andrews Experimental Forest in the western Cascade Mountains of Oregon, and its ability to simulate streamflow was evaluated. The simulation was conducted at 24-hour and one-hour time scales for the period of 1996 to 2005. The results indicated that runoffand peak discharge could be underestimated if snowpack accumulation and snowmelt under rain-on-snow conditions were not taken into account. The average deterministic coefficient of the hourly model in streamflow simulation in the calibration stage was 0.837, which was significantly improved over the value of 0.762 when the Xin＇anjiang model was used alone. Good simulation performance of the XINSNOBAL model in the WS 10 catchment, using the calibrated parameter of the Lookout Creek Watershed for proxy-basin testing, demonstrates that transplanting model parameters between similar watersheds can orovide a useful tool for discharge forecastin~, in un^au^ed basins.

关键词： Xin 'anjiang model " snow energy and mass balance model " rain-on-snow event " H. J.Andrews Experimental Forest