Agricultural production in the North China Plain with rainfall of less than500 mm·yr^(-1)has been steadily increasing over the past 40 years,with the groundwater levels decreasing at a rate of over 1 m·yr^(-1).In this paper,it is demonstrated theoretically that the water level in the aquifer can be expressed as a function of agricultural production and the sum of water added as rainfall and imported from outside the basin.Therefore,the most effective measures to halt groundwater depletion are importing water,decreasing cropping intensity and growing less thirsty crops.Irrigation improvements,mulching and agronomic measures that could increase the yield per unit area have less of an impact on solving the declining groundwater levels.
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