Abstract: From the perspective of transporting water to the air, the adverse effects of reducing rice planting area in Ningxia irrigation area were analyzed. The results showed that reducing the rice area of 10 000 hm², half of which was changed to corn area and the other half to wheat area, the water evapotranspiration would reduce by 3.032×10⁷ m³. Under the condition of concentrated continuous planting and calm wind, the air relative humidity would decrease by 11.6% from April to September. If the irrigation area reduced rice area by 10%~30% and changed to corn area and wheat area, the water transported to the air in the whole irrigation area would reduce by 2.5×10⁷~7.4×10⁷ m³, the groundwater level droped by 29.3~87.8 mm every year. It could be seen that the contribution of maintaining rice area to ecology was huge.

Key words: reduce rice area, water evapotranspiration, groundwater level, Ningxia irrigation district