基于游程理论的农业干旱指数在辽宁省春玉米旱灾损失评估中的应用

为准确识别农业干旱事件,评估干旱对农作物产量的影响,本文以辽宁省为例,基于52个气象站1961—2015年逐日气象数据,计算了春玉米全生育期水分亏缺距平指数,利用游程理论构建了一种新的春玉米全生育期干旱指数,再结合历年产量损失率构建了区、县级尺度的干旱产量损失评估模型,并对不同干旱风险下春玉米产量损失进行了评估,以明确辽宁省春玉米干旱重点防范区域。研究结果表明,辽宁省春玉米干旱指数呈由西向东递减的经向分布特征,辽西地区更易发生严重的干旱事件,且春玉米产量稳定性也最差。春玉米主产区内, 80%以上的区、县春玉米产量损失率与干旱指数呈显著线性正相关,辽中部分区县和辽东大部两者相关性不显著。相同干旱指数下,辽西产量损失率最大,并以朝阳地区为最;辽南和辽北次之;辽东湾和中部部分平原地区总体较小;非水分限制区辽东的凤城市和东港市,降水偏少反而更有利于春玉米产量提高。辽宁省春玉米干旱重点防范区域主要分布在辽西的朝阳地区,以及千山山脉以西和以北的辽北、辽南地区,提高和稳定春玉米产量需增加耐旱品种种植、发展节水灌溉、提高水分利用效率;降水充沛或灌溉条件较好、产量稳定性较高的辽东大部和辽中部分区县,可通过提高种植和管理水平、加强其他气象灾害防御等增加春玉米产量。

Application of agricultural drought index based on Run Theory for the assessment of yield loss in spring maize owing to drought in Liaoning Province

Drought is one of the main factors restricting agricultural development and food security in China. Identifying agricultural drought accurately and assessing the impact of drought on crop yield in detail is the core of drought research. The results of this research can provide a theoretical basis for drought disaster prevention and mitigation. The water deficit anomaly index of spring maize across the entire growth period was calculated based on daily weather data from 52 meteorological stations in Liaoning Province from 1961 to 2015, and a new drought index for spring maize over the entire growth period was constructed by using Run Theory. Drought yield loss assessment models at the county or city scales were further constructed based on the drought index and yield loss rate from 1981 to 2015. Finally, key prevention areas for spring maize drought in Liaoning Province were identified. The drought index for spring maize in Liaoning Province exhibited a decreasing distribution from west to east. The likelihood of severe drought events was higher and the interannual variability of spring maize yield was largest in western Liaoning. The rate of yield loss of spring maize had a significant positive linear correlation with the drought index in more than 80% of the counties in the spring maize main producing area, except for most parts of eastern Liaoning and some counties in central Liaoning. Moreover, significant spatial differences were observed in the yield loss of spring maize. With the same drought index, the region with the largest yield loss rate of Liaoning Province was Chaoyang, followed by the southern and northern parts of Liaoning; the Liaodong Bay and the central plain had the lowest yield loss rate. However, in Fengcheng City and Donggang City, where spring maize growth was not restricted by precipitation, the yield of corn was higher in the years with less precipitation. The results of the present study indicated that the government should pay more attention to drought-sensitive zones such as the Chaoyang District, and northern and southern Liaoning west, and north of the Qianshan Mountains. To increase and stabilize spring maize yield in the above areas, it is necessary to increase drought-tolerant varieties, develop water-saving irrigation, and improve water use efficiency. Most counties in eastern Liaoning and some counties in central Liaoning with abundant rainfall or good irrigation conditions can increase spring maize production by improving planting and management methods. Additional attention should be paid to the prevention of damage caused by floods and cold, especially in Fengcheng and Donggang.