全国水文预报技术竞赛参赛流域水文模型分析

对全国首次水文预报技术竞赛中参赛的10个流域水文模型的结构及模拟技术,分别从各个主要环节进行分类与综述;并根据技术竞赛检验结果所揭示的现象,就参赛水文模型的模拟及应用进行了分析与讨论。     

Floods in Bangladesh: A question of disciplining the rivers

Bangladesh has been experiencing floods more frequently than ever before. Since 1947, she has been hit by extremely devastating floods in 1954, 1955, 1956, 1962, 1963, 1966, 1968, 1969, 1970, 1971, 1974, 1976, 1984, 1987, and 1988. Each year's highest flood record and damage costs have been broken by that of the subsequent year. All means of communication become paralysed. People lose food grains, domestic animals, homesteads, and lives. They remain marooned without food and drinking water until relief arrives. Despite huge spending on flood control, the intensity of the floods has been increasing. Therefore, speculation is naturally rife about the causes.The aim of this paper is to identify the factors which contribute to these devastating floods, and then to recommend an appropriate strategy for effective flood control. The geography, geology, and hydrology of Bangladesh are briefly discussed. The whole of the country is a huge river basin criss-crossed by as many as seven hundred rivers, tributaries, and distributaries, having a total length of 22 155 km.The river-beds are rendered shallow by heavy deposits of alluvial earth each year and tend easily to cause inundations. The quantum of silt carried by the river systems into Bangladesh is estimated to be 2.4 × 10⁹ tonnes/yr.Disciplining the rivers means keeping the rivers navigable all year round, removing excessive deposits of silt where they threaten to block a channel, preventing widening by erosion, contracting the width where the river is excessively wide, and last but not least, preventing construction whose eventual impact might prove harmful.Natural disasters do not respect political frontiers, nothing can stop them, but their adverse impact could be minimised. The author emphasises the need for employing the abundant cheap manpower, local materials, and indigenous technology for flood control projects.     

Using the DPFT approach to improve flash flood forecasting models

DPFT is a lumped approach for operational flash flood forecasting, based on the unit hydrograph. Using a multi-event alternating iterative algorithm, it identifies a robust and stable average transfer function and a consistent set of effective rainfall series associated with each event at the same time. This key ingredient allows an objective calibration of different loss functions, relating gauged precipitation and effective rainfall. A case study based on an operational French basin (545 km²) is presented. Three lumped production functions have been calibrated and compared. The results show that more elaborate models of loss functions must be proposed, and some possible directions for this are pointed out.Presently at the Institut de Ciences de la Terra Jaume Almera, Apartat 30102, 08080 Barcelona, Spain.Presently at EDF-DTG. Service de Ressources en Eau, BP 4348, 31029 Toulouse Cedex, France.     

马尔柯夫链原理在海雾短期预报中的应用

本文应用了马尔柯夫链原理,采用转移概率矩阵的方法,建立了预报南海海雾的模式方程,且通过实际的业务试报反映出具有较好的预报能力。     

台湾地震区地震活动性的灰色预测

本文利用灰色系统理论中的GM(1,1)模型,对台湾地震区地震活动性进行预测,结果表明:①开始于1986年的第7个活动期将于1992年左右结束;②第7个平静期将于1993年左右开始并延续至1999年左右;③最近一次M_s=7.6级的大震发生在1986年11月15日,未来下一次7.5级以上地震预计将在1992年底发生,发震地区仍在本区的东带。     

青岛地区的台风暴潮灾度预报探讨

本文依据青岛沿海地区的台风暴潮成灾范围和经济失额划分了灾级；利用１９４９年以来青岛地区台风暴潮成灾个例，以潮位，波高以及他们的综合值为因子，运用逐步回归方法，建立了青岛地区台风暴潮灾度预报方程，经回报和后报检验，效果很好。     

A numerical forecasting model of offshore-SST anomaly

INTRODUCTIONTheO-SSTAisdefinedas:theSSTanomalyinoffshoreisover2twiththehorizontalscopeofover1"longitudemultipliedbyl'latitudeandthetime-scalesofover10d.ItisanoutstandingoceanographicphenomenonoccurringagainandagainintheChinaseasinallseasons.TheaffectingfactorsoftheO-SSTAhavebeendiscussedindetail,whichincludebothoftheresponseofupperoceantothestrongatmosphericsystemsandtheshallow-watereffects(Wangetal.,1998).HoweverthereisnoexplorationhowadynamicpredictingmodelofO-SSTAisdeveloped.Th…     

Study on short-range numerical forecasting of ocean current in the East China Sea-Ⅲ Three-dimensional baroclinic anomaly forecasting model and its application

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Ocean wave forecasting using recurrent neural networks

The tremendous increase in offshore operational activities demands improved wave forecasting techniques. With the knowledge of accurate wave conditions, it is possible to carry out the marine activities such as offshore drilling, naval operations, merchant vessel routing, nearshore construction, etc. more efficiently and safely. This paper describes an artificial neural network, namely recurrent neural network with rprop update algorithm and is applied for wave forecasting. Measured ocean waves off Marmugao, west coast of India are used for this study. Here, the recurrent neural network of 3, 6 and 12 hourly wave forecasting yields the correlation coefficients of 0.95, 0.90 and 0.87, respectively. This shows that the wave forecasting using recurrent neural network yields better results than the previous neural network application.     

Sequential forecasting of the surface and subsurface conditions in the Japan Sea

This study estimates a realistic change of the Japan Sea by assimilating satellite measurements into an eddy-resolving circulation model. Suboptimal but feasible assimilation schemes of approximate filtering and nudging play essential roles in the system. The sequential update of error covariance significantly outperforms the asymptotic covariance in the sequential assimilation due to the irregular sampling patterns from multiple altimeter satellites. The best estimates show an average rms difference of only 1.2°C from the radiometer data, and also explain about half of the sea level variance measured by the altimeter observation. The subsurface conditions associated with the mesoscale variabilities are also improved, especially in the Tsushima Warm Current region. It is demonstrated that the forecast limit strongly depends on variable, depth, and location.