Study of Farmland Water Resources in the Sandy and Windy Semi-Drought Area of Western Liaoning Orovince

The abundance and pinch of the rainfall alternate every two or three years in the Sand and Wind Semi-Drought Area of Liaoning province and the arid climate may last for 4 years sometimes. The dry condition became more and more severe after 1980. In the Sand and Wind semi-Drought Area, in spring the arid climate is very severe, in summer the rainwater is abundant, and in autumn the income and expenses of soil water is balanceable. The change of soil water with time could be divided into four phases-the phase of sil water agglomerating, freezing up and accumulating in winter; the phase of soil water fast vaporizing in spring; the phase of soil water accumulating in summer; and the phase of soil water slowly vaporizing in the autumn.