By using linear regression, moving average, Mann-Kendall test and Morlet wavelet analysis method, the annual, flood seasonal and dry seasonal precipitation series during 1954~2008 in Weihe River basin are analyzed. The results indicate that: ①Annual precipitation and precipitation in flood season and dry season present decreasing trends during the past 55 years, and the variation trends are not significant. ②There is an irregular spatial distribution of mean annual precipitation, which shows a decreasing trend from southeast to northwest. ③Annual precipitation exists principal periods of about 2, 10, 17 and 50 years, and the phase changes of 2 and 50 years period are most obvious. Time scales of phase change of precipitation series in flood season and dry season are roughly consistent with those in annual. The research results will provide reference for climate analysis and future weather forecasting in Weihe River basin.
Abstract. Many factors influence irrigation water requirement on the basin scale, which make it difficult to obtain comprehensive data. Despite the advantage of less needing historical data, the prediction precision of traditional trend prediction methods is hard to guarantee. For water scarce basins, the artificial influence on irrigation requirement should be thought of as important impact factors. In this paper, the PCA (principal component analysis) method is used to identify the main influencing factors, such as precipitation, irrigation area, water saving technology and so on. Based on that, an irrigation water demand prediction model considering multiple factors is developed for water shortage regions. The method is applied in the Haihe River basin as an example. The study results show that the irrigation water demand forecasting method considering multiple factors in this paper can achieve higher modelling accuracy, compared with the traditional trend prediction method and the method that does not consider the human influence. In view of the small average relative error, 1.32%, it has good values for application.
This paper takes a typical channel passage in the middle route of the South-to-North water diversion project as an example to study emergency control strategies for unexpected water pollution accidents. A one-dimensional Saint Venant equation and water quality numerical model is developed, considering limitations such as the migration velocity of pollutants, water level fluctuation, and variations in the channel. Emergency control strategies for each gate are proposed for unexpected water pollution accidents and gate closing rules are established. Parameters such as the channel water depletion rate, stabilization time, water level fluctuation, and water quality are simulated under different control strategies in order to ensure the safe operation of water transport and to decide on the control strategy for unexpected water pollution accidents. Such studies can provide reference information for the development of emergency strategies in the middle route of the South-to-North water diversion project.
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