长江流域冬油菜需水量及水分盈亏特征分析

Analysis of water requirement and water surplus/deficit characteristics of winter rapeseed in Yangtze River Basin

基于长江流域冬油菜优势产区11个省、2个直辖市共计129个城市近20年的逐日气象数据,采用经验公式、FAO推荐的改进HS数据模型和作物系数分别计算各城市冬油菜全生育期及各生育阶段有效降水量及需水量,并对水分盈亏指数及多年旱涝灾害发生频率进行分析。结果表明,长江流域冬油菜在各生育阶段有效降水量均呈由东南向西北递减的带状分布特征,其中鄱阳、洞庭两湖平原及杭嘉湖平原有效降水量充沛,长江中下游干流南北沿岸地区有效降水量适中,秦岭—淮河一线、四川盆地及云贵高原有效降水量偏少;各生育阶段的需水量呈现西南高、东南中、西北低的分布特征,其中云南省需水量最高,长江中下游平原需水量适中,秦岭—淮河一线、四川盆地、贵州省需水量最低;多年水分盈亏空间分布特征表现为长江中下游干流南北沿岸地区水分供应适中,秦岭—淮河一线、四川盆地、云贵高原水分供应不足;水分盈亏年代演变特征表现为苗期长江上游旱灾多发、涝灾偶发,中下游涝灾多发、旱灾偶发,其他生育阶段长江上游旱灾频发,中下游旱灾多发、涝灾偶发的特征。为有效保障长江流域冬油菜各生育阶段的适当水分供应,在苗期阶段,长江上游地区应注意适量灌溉、中下游地区应注意及时排涝;其他生育阶段,长江上游地区应注意充分灌溉,中下游干流北岸城市应注意适时灌溉,中下游干流南岸城市应注意适时排涝,以促进长江流域冬油菜高产稳产,保障国内油菜籽原料稳定供应。

Based on the daily meteorological data of 129 cities in 11 provinces and 2 municipalities in the Yangtze River Basin for nearly 20 years,the effective precipitation and water requirement of winter rapeseed during the whole growth period and various growth stages were calculated by empirical formulas,the improved HS data model recommended by Food and Agriculture Organization(FAO),and crop coefficients.Furthermore,the water surplus/deficit index and the frequency of droughts and waterlogging disasters over multiple years were analyzed.The results indicated that the effective precipitation during various growth stages of winter rapeseed in the Yangtze River Basin had a decreasing belt-like distribution from southeast to northwest.Specifically,the plains around Poyang Lake and Dongting Lake,as well as Hangzhou-Jiaxing-Huzhou Plain,had abundant effective precipitation,while the effective precipitation in the coastal areas of the middle and lower reaches of the Yangtze River mainstream was moderate.Conversely,the effective precipitation was relatively low along the line from Qinling Mountains to Huaihe River,in Sichuan Basin,and on Yungui Plateau.The water requirement during various growth stages exhibits a distribution pattern of high in the southwest,moderate in the southeast,and low in the northwest.Among them,the water requirement was the highest in Yunnan Province,moderate in the plains of the middle and lower reaches of the Yangtze River,and the lowest in the areas along the line from Qinling Mountains to Huaihe River,in Sichuan Basin and Guizhou province.The spatial distribution characteristics of water surplus/deficit over multiple years indicated moderate water supply in the coastal areas of the middle and lower reaches of Yangtze River mainstream,insufficient water supply along the line from Qinling Mountains to Huaihe River,in Sichuan Basin,and on Yungui Plateau.The temporal evolution characteristics of water surplus/deficit indicated that droughts are more frequent at seedling stage in the upper reaches of the Yangtze River,with the occasional occurrences of waterlogging disasters,while waterlogging disasters were more frequent in the middle and lower reaches,with the occasional occurrences of droughts.At other growth stages,droughts were frequent in the upper reaches,while both droughts and waterlogging disasters were frequent in the middle and lower reaches.To ensure appropriate water supply at various growth stages of winter rapeseed in Yangtze River Basin,it was recommended to focus on adequate irrigation in the upper reaches at seedling stage and timely drainage in the middle and lower reaches.At other growth stages,sufficient irrigation should be emphasized in the upper reaches,timely irrigation in the cities on the northern bank of the mainstream in the middle and lower reaches,and timely drainage in the cities on the southern bank of the mainstream in the middle and lower reaches,aiming to promote high and stable yields of winter rapeseed in Yangtze River Basin and ensure a stable supply of domestic rapeseed raw materials.