Fig. 1 indicates the geographic location of the study area and
Table 1 shows the natural and socio-economic characteristics of the
study area. Politically and economically, Gansu province has been
considered as a remote backward north-west province, but
geographically, Gansu province is almost located in the central part
of China (92130e108460E, 32310e42570N). It is located in the
convergence zone of the Loess Plateau, the QinghaieTibetan
Plateau, and the Mongolian Plateau. It is characterized by complex
topography, criss-cross mountains and significantly different altitudes
over different areas. It has diversified climate zones from the
east to the west. The eastern and northern areas containing hot
humid zones of north Asia and multiple meteorological types of
cold drought zones. Generally, the climate of Gansu is temperate,
semi-arid, with annual precipitation ranging between 36.6mmand
760 mm, but the average annual precipitation is 300 mm. The
rainfall is mainly concentrated between June and September with
large inter-annual variations. There is strong solar radiation; its
annual sunshine time can reach 1700e3300 h. The annual average
temperature varies from 0C to 14C. There are 25.78 million people
in the province, of whom farmers account for 15.79 million, or
61.25% of the total population. The farmers’ average net income per
capita per year was RMB 4495 (equivalent to about USD 725) in
2012.