三江平原挠力河流域主要作物水分盈亏时空变化特征

明确中国粮食生产基地主要作物种植条件下的水分盈亏条件,有利于区域灌溉策略制定及保障国家粮食安全。该研究基于MODIS遥感数据和常规气象数据,运用Priestley-Taylor公式以及作物水分盈亏指数,以三江平原腹地的挠力河流域为研究区,揭示2000年以来该流域主要作物(中稻、春小麦和春玉米)的水分盈亏时空变化特征。结果表明:1)挠力河流域潜在蒸散量由2000年的910.25 mm增至2015年的964.04 mm,各作物需水量整体呈现不同幅度的上升态势;2)各作物表现出不同的水分盈亏特点。中稻水分亏缺明显,缺水量由东北向西南递增,天然降水不能满足其水分需求。春小麦水分亏缺程度低,灌溉需求量在空间上变化较小。春玉米多处于轻度缺水状态,且西北部的缺水量小于东南部;3)流域境内的中稻多处于轻旱状态,2000—2015年干旱区持续扩张,面积增长幅度达到143.46%。对于旱作物而言,春小麦的缺水量尚未达到轻旱的标准,而春玉米的轻旱区面积往复变化,2000—2015年间面积减少了79.90%。作物种植结构的快速变化,使得中稻种植区迅速扩张,加剧了该流域的水分亏缺态势,而春小麦和春玉米的种植区变化未对水分盈亏态势造成显著影响。研究可为挠力河流域的农业结构调整与农田灌溉措施制定提供支持。

Spatial-temporal characteristics of water surplus and deficit for the main crops in Naoli River Basin of Sanjiang Plain, China

Abstract: Naoli River Basin is located within the Sanjiang Plain in Heilongjiang Province, China. The agricultural structure of Sanjiang Plain has been greatly adjusted with a large amount of dry land crops into wetland rice since the early 2000s, thereby resulting in a series of problems in the utilization of water resources in Naoli River Basin. Therefore, it is necessary to explore the water profit and loss situation of main crops, in order to implement regional irrigation strategies, and thereby to serve as the national food security. In this study, the Priestley Taylor formula, and Crop Water Surplus and Deficit Index (CWSDI) were used to reveal the water profit and loss situation of the middle rice, spring wheat and spring maize, in Naoli River Basin. The fundamental resources included the MODIS image, the long-term sequenced meteorological and the DEM data sets during the processing. Results showed that the Potential Evapotranspiration (ET0) increased from 910.25 mm in 2000 to 964.04 mm in 2015 in this river basin. The water demand of main crops, including middle crop, spring wheat and spring maize, also increased at different ranges as a whole. There was a decrease trend in the CWSDI from 2000 to 2015 in Naoli River Basin, indicating the natural precipitations can not meet the irrigation demand of middle rice, while the absolute value of index increased from the northeast to southwest in the spatial distribution. The CWSDI of spring wheat was larger than that of the middle rice, showing similar characteristics in the whole spatial distribution for each year. The CWSDI of spring maize indicated that the spatial characteristics of northwest were slightly lower than that of the southeast, indicating both regions in the condition of mild water shortage in Naoli River Basin. Drought classification was also evaluated using the CWSDI. The middle rice, accounting for the area proportion of 143.46%, was basically in mild drought state in the research basin. Despite at the state of water shortage, spring wheat has not reached the drought standard. The cultivated area of spring maize has decreased by 79.90% in the mild drought state in Naoli River Basin. The reason can be that the spring wheat and spring maize have been partly substituted for the middle rice with a rapid increasing trend since 2000, and thereby the planting of wetland crops, such as rice, led to a severe shortage of water. The spring wheat and spring maize demonstrated an extremely rare negative impact on the water surplus and deficit situation. These findings can provide the promising references when implementing the farmland irrigation schemes and agricultural structure adjustment in Naoli River Basin, China.