Application of Wavelet Fractal Dimension Estimation in Dividing Flood Stages for Three Gorges Reservoir
Abstract Limit water level control improves water resources utilization efficiency without reducing flood control standard, while the premise is to divide the discharge series into a number of different flood stages. Db4 is selected as wavelet base, based on Mallat algorithm, put forward the model of wavelet dimension estimation method and calculated the fractal dimension of floods at the Yichang station, got the flood periods of Three Gorges reservoir. The results indicate that the method of wavelet dimension estimation can obtain the same result as traditional methods, and it has the merit of simplicity and stability. As a feasible and effective tool, the wavelet dimension estimation method is recommended in the applications of dividing flood periods.
Identification of Flood Seasonality by Circular Distribution Method
Circular distribution was used to calculate flood concentration period and degree as well as the start and end time of flood peak hydrograph for the identification of flood seasonality.Application results of the Three Gorge Reservoir show that flood seasonality determined by proposed method is reasonable and reliable.Statistical experiment indicates that circular distribution with consideration of flood magnitudes performs best.The circular distribution method can describe seasonal flood characteristics well and provide a new approach for seasonal flood analysis.
The incidence of dead and dying fish in the Moray Firth, September 1963
Dead and dying fish were reported from the Moray Firth during a period of 15 days in September 1963. The initial mortalities were in the inner Firth, but they later spread outwards, especially eastwards along the southern shores of the Firth. Mass mortalities of the lugworm (Arenicola marina) also occurred in Scottish waters in 1962 and 1963, and at Balintorein Easter Ross fish and lugworm mortalities were contemporary.