Relationship between decline of shallow groundwater levels and irrigated agriculture on Hufu Plain of North China

Focusing onthe problems of continually declining shallow groundwater levels on the Hufu plain of North China, the variations and response mechanisms of groundwater levels, grain and vegetable planting intensity, effective irrigated areas and precipitation are studied.A large amount of observational data collected in the past 50 years is analyzed using statistical methods and the MapGIS technology.Results show that before 1980s, the magnitude of decline in groundwater levels is small in response to the increase in the grain and vegetable planting intensity.The decline would be 0.36 m and 0.43 m, respectively; should the planting intensity and the sown area of summer grain crops and vegetables increase 0.01 and 10000 hm², respectively.However, a significant decline in groundwater levels has been observed since 1980s.The decline would be 0.69 m and 1.15 m, respectively, with the same changes in both planting intensity and sown area of summer grain crops and vegetables.Such a decline is not only the result of the increase in the grain and vegetable planting intensity, but the result of the decrease in annual precipitation on the plain.Should there be a reduction of 100 mm in annual precipitation; the groundwater exploitation for agricultural irrigation would be increased by 35.7 mm.