华北平原综合作物需水量空间分布特征及影响机制研究

Crop water requirement is the basic data for the assessment of agricultural efficient water use and irrigation management of irrigation district. In different time and space scales, due to the randomness and uncertainty of climate, topography, crops, soil moisture and other influencing factors, crop water demand is spatially heterogeneous. It is a research difficulty to increase and expand the spatial scale of crop water requirements from farmland to the regional scale. .Taking the crop water requirements in the North China Plain as the target, based on the collected water demand data, this study uses the GIS technology and geostatistical method to propose the concept and calculation method of equivalent crop coefficient and integrated crop water requirements. The equivalent crop coefficient is the ratio of the weighted sum of the water demand areas of all crops in a certain stage of a region (ie, the integrated crop water requirements) to the reference evapotranspiration. This study explores the spatial distribution characteristics of integrated crop water requirements in North China Plain, reveals the influencing mechanism of environmental factors and geographical factors on the integrated crop water requirements, and further establishes the spatial distribution model of integrated crop water requirements. The study provides a theoretical basis for the improvement of the spatial scale for crop water requirements and provides technical support for calculating regional crop water demand as well as agricultural irrigation water consumption. It is of theoretical and practical significance to improve the accuracy of crop water requirements in areas without data or with sparse sites, optimize regional irrigation system, and achieve sustainable development of regional agriculture.

作物需水量是农业高效用水评价和灌区灌溉管理的基础数据。不同时空尺度范围内，由于气候、地形、作物、土壤水分等影响因子具有随机性和不确定性，使得作物需水具有空间异质性。作物需水量空间尺度从农田向区域的提升，是作物需水量研究的难点。.以华北平原区域作物需水量为对象，基于收集的需水量资料，运用GIS技术和地统计学方法，尝试提出等效作物系数和综合作物需水量的概念及计算方法。等效作物系数即一个区域某阶段所有农作物需水量面积加权之和（即综合作物需水量）与参考作物腾发量的比值。探索华北平原综合作物需水量的空间分布特征，揭示环境因子和地理要素等对综合作物需水量的影响机制，进一步建立综合作物需水量空间分布模型。研究为作物需水量空间尺度提升提供理论依据，为计算区域作物需水量及农业灌溉用水量提供技术支撑，对提高无资料或站点稀疏地区需水量计算精度、优化区域灌溉制度、实现区域农业可持续发展有着重要的理论和实践意义。

农业用水占全国用水总量的62.4%，灌溉用水占全国农业用水的90%以上。农业灌溉用水量的计算往往需要耗费巨大的物力、人力，计算数种作物的作物需水量、净灌溉定额，各省份协同工作时往往存在不同的计算标准。基于开展的需水量试验和收集的2000年以来灌溉试验站网需水量试验资料，本项目以华北平原作物需水量为对象，将各种作物归一化和标准化，提出全新的概念—等效作物系数和综合作物需水量的概念和计算方法。等效作物系数即一个区域某阶段所有农作物需水量面积加权之和（即综合作物需水量）与参考作物腾发量的比值。系统分析华北平原综合作物需水量的时空分布特征，建立综合作物需水量的空间分布模型，为计算区域作物需水量及农业灌溉用水量提供新思路，为正确评价区域农业用水和农业节水潜力提供科学方法。