不同水文频率下关中灌区农业节水潜力研究

农业节水潜力研究对节水农业发展具有重要影响。本文将农业节水潜力分为资源型和效率型两类,分别代表了田间或灌区尺度和流域大尺度的节水潜力。以渭河流域关中段九大灌区为例,进行了灌区农业节水潜力分析;并针对典型灌区主要作物的不同节水方案,分析计算了在不同水文频率年下的农业节水潜力。结果表明:在25%、50%、75%和90%水文频率下,渭河流域关中段九大灌区年农业节水潜力分别达3 069万m3、11 167万m3、11 750万m3和12 521万m3,其中效率型节水潜力所占比例较大,除25%频率下仅有42%外,其他频率下均超过50%。最后,基于现状节水技术水平,根据九大灌区的种植结构特点,提出了提高农业节水潜力的措施和建议。该研究结果可为发展关中地区各灌区农业节水技术和提高水资源利用效率提供参考。

Agricultural water-saving potential in Guanzhong Irrigation Area in different hydrologic years

There has been a rampant water shortage in the Wei River Basin in recent years, significantly affecting the ecological and economic functions of the river and drastically limiting the socio-economic development of the administrative regions within the basin. Although the respective local/national governments have adopted adjustment strategies of the water use structure, agriculture has remained the biggest water user, accounting for over half of total water use in the basin. Meanwhile, agricultural water use efficiency in the basin has been some 1 kg·m^-3, much lower than that in developed countries like Israel and USA. The main reasons for the low agricultural water use efficiency have included low use of advanced technology (e.g., springklers, drop irrigation and mulching), low channel lining rates and high water contamination. In this study, we summarized the current state and trend in agricultural irrigation, calculated the agricultural water-saving potential and then developed a new mode based on current and future crop water requirement. The two main modules of the mode (resource-based water-saving and efficiency-based water-saving) were respectively representative of small-scale and large-scale water analysis. Based on main crops in typical irrigation areas, different water-saving schemes were designed and the water-saving potential of each scheme calculated. The probable water-saving amounts in the nine irrigation districts were analyzed and calculated for different hydrologic years. For instance, in years with water guarantee rates of 25%, 50%, 75% and 95%, agricultural water-saving potentials in Guanzhong Irrigation Area were respectively 30.69 million m³, 111.67 million m³, 117.50 million m³ and 125.21 million m³. Efficiency-based water-saving potential was over 50%, expect for the 25% rate water guarantee condition where it was 42%. Then based on present water-saving technology and planting structure characteristics of the nine irrigation areas, a water-saving mode was put forward which reduced water diversion by 10% and improved agricultural irrigation water use efficiency by 5%. Exploitation of agricultural water-saving potential was the basis for water resources reallocation in the region. This study also laid the base for theoretical and technical support for the development of water-saving irrigated agriculture, planning of water resources reallocation and construction of water-saving society.