With the economic growth, continuous global environment deterioration, and increasingly serious water resources shortage, droughts have become more and more serious and produced great impacts on both the regional ecology and sustainable economic development. This paper has established the "green, blue, yellow, orange, and red lights" as the early warning grades for agricultural droughts. By using the two influencing factors, namely precipitation and soil moisture, this paper has established the drought assessment index evaluation model using weighted coupling method. It has carried out the analogue simulation of the early drought warning based on the Jinghui Channel's 2013 water source situations. The soil moisture in January and February is relatively ideal, and the actual early drought warning is expressed by the "green light". The soil moisture deficit is comparatively serious in March, but the situation concerning water inflow is ideal with the "green light". Actually, the early warning signal is basically consistent with the soil moisture drought degree between April and August. The actual early warning is expressed by the "green light" as well, but the soil moisture is not so ideal, however, this is the seeding time of the winter wheat so the lack of soil moisture has no impact on the crops output. In November and December, the winter wheat is at the growth and development stage and does not need much moisture. At this stage, the soil moisture is relatively poor. By integrating the time effects into the early drought warning system, this paper provides administrators of irrigation areas with a scientific decision-making based on the drought control measures.
Keywords: drought index; early droughts warning and drought assessment; precipitation; soil moisture.