Regional metallogeny is depedent upon a series of factors other than composition and age of magmatic rock, erosional level of ore-bearing batholith or magmatic assimination of sedimentary rock.

The slope erosion is the original zone of water and soil loss and water and soil on slope must be treated quickly.

According to observation data and the outcomes of artificial rainfall in Wangjiaqiao basin, based on erosion mechanics mechanism, two concepts of slope erosion and basin erosion are distinguished grimly and soil erosion models of slope and small watershed have been established.

There is serious slope erosion when the railway or road is constructed in granite region in southern China where ecological environment and engineering conditions is weak area in.

It is considered that the slope surface erosion is the inducing and promoting factor of the gradual destruction of the loess slope in long-term rainfall wash and infiltration,whose surface is exposed and within which is the slippage interface.

From the following four aspects: drag forces, velocity, energy and sediment carrying capability of slope surface flow, the threshold gradient of slope surface erosion in the granite area in the south of china is discussed, and it is obtained the critical slope gradient is from 35 to 43 degree.

However, soil erosion and seasonal drought are major constraint for sustainable agriculture due to improper land use and uneven distribution of .