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[Technology of preventing Oncomelania snail diffusion in east route of South-to-North Water Diversion Project. I. Field test of blocking diffusion of Oncomelania snails with blocking network via collecting water from middle layer].

OBJECTIVE
To evaluate the effectiveness of blocking diffusion of Oncomelania snails with the blocking network via collecting water from middle layer.


METHODS
According to the principle of the installation preventing snails via collecting water from middle layer without snails, the blocking network was manufactured. The field test of the blocking diffusion of snails with the blocking network was carried out in the electric pumping station and the irrigation located in the area with snails. The snails stained were put into the water inlet of the pump when the pump was actuating, and the snails pumped were observed during the test period. The cost of the test was also calculated.


RESULTS
The rate of blocking diffusion of snails with the blocking network was 100%, and the direct costs were only 11 030 CNY.


CONCLUSIONS
The blocking network via collecting water from middle layer has good effect for prevention of snail dispersal. It is simple for manutacturing and installation, and suitable for emergency blocking diffusion of snails in the east route of South-to-North Water Diversion Project and the electric pumping station with snails.