甘肃省河东地区春玉米干旱演变特征及灾损风险区划

甘肃河东地区为全省春玉米主要种植区,同时也是易发生干旱的地区,基于FAO推荐的Penman-Montith模型以及其提供的作物系数计算了甘肃省河东地区春玉米作物水分亏缺距平指数(CWDI_a),采用甘肃省河东地区54个气象站1961—2017年逐日气象数据以及河东各县(区)春玉米多年产量资料,从干旱的年际变化趋势、干旱空间分布特征以及春玉米干旱灾损风险区划三方面对近57年来河东地区春玉米各生育期干旱演变特征及其灾损风险区划进行了分析。结果表明:受降水的影响,河东地区春玉米生长期各旬需水量、CWDI_a值均呈先增大后减少的趋势,全区CWDI_a值15,表明该区虽为雨养农业区但仍需通过灌溉补给保证作物生长期所需水分。生长季内春玉米水分亏缺的变化幅度:抽雄～开花期拔节期乳熟～成熟期出苗～七叶期。出苗～七叶期水分亏缺程度由南向北呈递减趋势,其他三期水分亏缺程度由南向北呈递增趋势。河东地区春玉米干旱风险具有明显的区域性和差异性,低风险区主要在陇东南部地区,陇南中部、北部、南部地区,甘南高原东北部地区;中风险区主要在陇东中部地区,陇南东南部地区,陇西黄土高原中部地区;较高风险区主要在环县,渭北地区;高风险区主要在黄河以南地区至靖远-榆中区。总体来看,河东春玉米干旱灾损风险区由南向北呈纬向分布,且受积温影响,海拔高于2 500 m的高山区不适于种植春玉米。

Drought evolution characteristics and risk zoning of spring maize in Hedong of Gansu Province

Hedong is a main production area of spring maize in Gansu Province, and also an area prone to drought. In this paper, based on the Penman-Montith model recommended by FAO and the crop coefficient provided, we calculated the crop water deficit anomaly index (CWDI_a) of Hedong. After studying the daily meteorological data from 54 weather stations and the production data of spring maize from 1961 to 2017 in the east of Gansu and based on the trend of the inter-annual variability of drought, drought in spatial distribution, and drought damage risk zoning, the drought evolution characteristics and damage risk zoning were analyzed in the growth period of spring maize in recent 57 years in the Hedong. The results showed that due to precipitation, the water requirement in every ten days and CWDI_a of spring maize in Hedong firstly increased then decreased.This area is a rain-fed agricultural area, but high CWDI_avalues (>15) showed that it needed irrigation to meet the water requirement of spring maize in growing season.The spring maize water deficit during growth period ranged as:tasseling stage to flowering stage> jointing stage> milk stage to mature stage > emergence stage to seven leaf stage.The degree of drought in emergence stage to seven leaf stage decreased from the south to north and the degree of other stages increased from the south to north.The drought risk of spring maize in Hedong region had significant difference among regions. The low-risk regions were mainly in southern Longdong, central Longnan, northern and southern Longnan, and northeastern Gannan Plateau regions. The middle risk areas were the central region of Longdong, the southeastern region of Longnan, and the central region of Loess Plateau of Longxi. The main risk areas were mainly Huanxian,Weibei. The high risk area mainly distributed in south region of the Yellow River to Jingyuan-Yuzhong. In general, the risk zoning of drought damage to spring maize in the Hedong area distributed latitudinally from the south to north. Affected by accumulated temperature, JP3]the mountain area above 2 500 m elevation in Hedong is not suitable for spring maize cultivation.