Effect of the water change on the agricultural production and its countermeasures in the Huang-Huai-Hai Plain

The distributions of time and space and the yield-increasing benefits of waterdiverting irrigation from the Huanghe River in the Huang-Huai-Hai Plain were briefly researched. The amount of water-diverting was 10.78 billion m³ at the lower reaches of the river from 1990 to 1995. The yield-incr easing benefit of the irrigation was 2650kg/hm² for grain, and 558kg/hm² for cotton in the area from 1992 to 1996. The frequency and the effect of absence of flow in the river were analyzed. The accumulative water-off days were 392 days for Luokou Station and 859 days for Lijin Station from 1990 to 1998. The countermeasures of agricultural water management in the area where water resources are deficient were inquired into, that consist of the effects of the different water supply projects on the agricultural production, the region regulations of the grain production patterns and the measures of the developing resources and reducing expenditure for agricultural water management.