沱江流域中游洪水前后生物量变化特征分析

Characteristics of Biomass Changes Before and After the Flood in the Middle Reaches of Tuojiang River

沱江流域中游位于四川盆地中西部,是长江上游流域重要的粮仓和人口聚集区。2018年7月以来发生的强降雨对农作物生长造成一定影响,为定量分析沱江流域中游洪水前后的生物量指标变化情况,选取6月6日和8月20日两个时期的Sentinel-2数据,提取每个时期的叶面积指数、光合有效辐射吸收率、冠层含水率、叶绿素含量及植被覆盖等度生物量指标。对生物量指标图像特征、空间区位等分析,得出光合有效辐射吸收率受洪水灾害影响最小,而叶面积指数和叶绿素含量受其洪水灾害影响较大;沱江流域中游农作物虽受洪水灾害影响,但作物生长趋势仍然处于增长状态;流域主河道植被光合作用受洪水灾害影响较大,支流区域影响较小,该研究结论为农业部门科学指导提供解决措施和研究方案。

Located in the central west part of Sichuan Basin,the middle reaches of Tuojiang river is an important granary and population gathering area in the upper reaches of Yangtze river.Its biological growth has been affected by heavy rainfall since July 2018.To quantitatively analyze the changes of biomass indicators before and after the flood,Sentinel-2 datum from June 6,2018 and August 20,2018 are selected and five biomass indicators are extracted,including leaf area index,photosynthetic effective radiation absorption rate,canopy water content,chlorophyll content and vegetation cover.Through the analysis of image characteristics and spatial location changes of these biomass indicators,it is concluded that the photosynthetic effective radiation absorption rate is least affected by the flood while the leaf area index and chlorophyll content are greatly affected;the growth trend of the crops is still on the rise despite of the adverse impact;the vegetation photosynthesis of main river channel has suffered a lot from the flood but the tributary area has been less impacted.These research conclusions have provided solutions and research programs for the scientific guidance of agricultural departments.