Impact analysis of land use on groundwater level drawdown:a case study of the Hebei Plain
XU Yue-qing (Department of Resource, Environment and Geography, the Center for Land Study, Peking University; Key Laboratory for Earth Surface Processes, the Ministry of Education, Beijing 100871, China)
Adopting the simplified water balance model, the average infiltration coefficient of precipitation and specific yield in the Hebei Plain between 1985-1995 are simulated, and the annual average groundwater level dropping down by water use sectors and crops is calculated on the basis of the above simulations. The results show that the water use in agriculture is the main factor resulting in the decline of groundwater level in the Hebei Plain, and the industrial and domestic factors are the secondary. In the piedmont plain, agriculture has led to a decrease of 0. 63 m per year, industry of 0. 08 m and domestic of 0. 03 m, with the individual ratios being 85. 1% , 10. 8% and 4. 1% respectively. While in the low plain, the order of the decrease is 0. 23 m, 0. 005 m and 0. 015 m per year with the ratios being 92. 1%, 2. 0%, and 5. 9% accordingly. In both areas, as to the major role causing the decline of groundwater level among the crops, wheat is the first, being 0. 33 m and 0. 127 m per year, while millet is the least, being 0.01m and 0. 004 m annually. As for water consumed in producing unit output value, wheat also occupies the first place, being 1. 35m3/yuan and 0. 91m3/yuan, or resulting in the largest decline of 0. 02 m and 0. 008 m in producing 100 million yuan of wheat each. While vegetable is the least, being 0. 25 m3/ yuan and 0. 19 m3/yuan, or 0. 004 m and 0. 002 m decline per 100 million yuan. With the decline of groundwater level, a series ecological and environmental disasters have been caused which have become the key factors restricting the socio-economic sustainable development of the Hebei Plain. Therefore, it is high time to adjust planting structure in order to achieve sustainable use of the groundwater in the Hebei Plain.