Determination of water price and estimation of water savings and emission reduction in groundwater irrigation areas: A case study of Nanpi County, Hebei Province

A comprehensive reform of agricultural water prices is required to study and propose a reasonable water price adjustment scheme. The method regarding the determination of water price and the estimation of water savings and pollutant emission reduction in groundwater irrigation areas were proposed, and the current irrigation water use and current water price were calculated by using the method of “converting electricity into the water”. The double logarithm model was used to establish the price elasticity function of irrigation water demand. The ideal water price was calculated using the residual value method, and the pollutant emission reduction from water savings was calculated using the farmland pollution logistics loss model. Taking Nanpi County of Hebei Province as an example, the results showed that the current water prices of wheat and corn are 0.44 ¥∙m⁻³ and 0.48 ¥∙m⁻³, respectively. The water price elasticity coefficients of wheat and corn are −0.47 and −0.71, respectively. The actual water prices of wheat and corn corresponding to the irrigation quota are 0.52 ¥∙m⁻³ and 0.77 ¥∙m⁻³, respectively, and the ideal water prices are 0.84 ¥∙m⁻³ and 1.01 ¥∙m⁻³, respectively. As per the recommended scheme, the theoretical water price accounts for less than 15% of the total cost, the increased range for water price of wheat and corn is 0.08 ¥∙m⁻³ and 0.29 ¥∙m⁻³, respectively; and the water-saving potential is 235.05 m³∙hm⁻², 682.80 m³∙hm⁻². The nutrient emission reduction of ammonia nitrogen, total nitrogen, and total phosphorus are 5.2−19.2 g∙hm⁻², 52.7−195.4 g∙hm⁻², and 4.6−16.9 g∙hm⁻² for wheat; and 18.5−27.6 g∙hm⁻², 189.1−281.2 g∙hm⁻², and 16.3−24.3 g∙hm⁻² for corn, respectively. As the comprehensive reform of agricultural water prices is a systematic project, it needs the support of relevant supporting policies. This study suggests the adoption of water-saving technology, land transfer, large-scale operation, and irrigation quota management systems to promote comprehensive reform of agricultural water prices through relevant incentive policies.