The principle and indexes for dividing zones of rosional landform type are discussed in the paper. Based on the principle
and indexes, the whole
middle Yellow River Basin is divided into 4 zones of I class, 20 class n zones, and 556 type patches. Using data of 155 sediment detentionbarriers which check all oncoming sediment and water flow, a erosion model with different weight is constructed. The model relates the amount of sediment deposited in the barriers with 5 factors influencing erosion in the basins upstream of the barriers.The yield of sediment erosion of every type patches was calculated by the model, and a map of erosional module contour was edited. It is found that most of the error between the calculated and measured
sediment yield in various space scales are about ?0%. The total sediment yield of the patches is 14. 655 X 10" t/a in the period of 1970~1989.The spatial distribution of erosion intensity is revealed by the map clearly. It is lower than 5 000 t/km2 ?a to the west of Liupan Mt. , and to the east of Luliang Mt. In the area between Liupan and Luliang Mts, the erosion intensity declines southward from over 18 000 t/km ?a at Jungar and Fugu, 15 000 t/km2 ?a at Suide and Mizhi. 6 500 t/km' ?a at Yan'an, to lower than 1 OOOt/knT ?a.The landform and ground surface material are defined as static factors, vegtation, precipi-tation and human impact as dynamic ones in the paper. Under the prerequisite of self-sufficiency in grain in the area, the values of dynamic factors in the middle of the next century are predicted for every patches. The sediment yield from these patches are reckoned by using the same model, and the total yield is 12. 28X 10* t/a in the middle of the next century.