Tendency analysis indicate that the yearly runoff of three typical basins (Dali river, Hailiutu river and Xiaoli river), which belong to riverhead gully section, sand and wind section and hill section respectively changed consistently in 1970, namely the annual runoff has showed decreasing tendency since 1970. Compared with the runoff in 1959~1969, the average extents of water reduction in riverhead gully section (Dali river) and hill section (Xiaoli river) are maximal, namely 36.33 % and 36.21 %, respectiv...
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