Using the meteorological data

vegetation distribution data

water resources data

we calculated the minimum and appropriate ecological water requirement of existent forest and grassland in growing season in the Central and Southern Ningxia Hui Autonomous Region. Through the analysis of equilibrium between the eco-environment water demand and rainfall resource

the results showed that in Longde County and Jingyuan County

which locate in the south area

with an average rainfall of 350~550 mm

the minimum and appropriate ecological water requirement both can be met by precipitation

and the vegetation grow well. In Pengyang County and Yuanzhou County

which locate in the south area

with an average annual rainfall of 350 mm or so

the minimum eco-water demand can be satisfied

but appropriate ecological water demand cannot be met. So reasonable grass planting structure should be considered in the area. In Haiyuan

Yanchi and Tongxin Counties in the central arid area and Xiji County in the south area

with an average annually rainfall between 175 and 280 mm

both minimum and appropriate ecological water demand can not be met

it is unreasonable to develop forest and grassland in this area.