A total of 491 Landsat satellite images from 1973 to 2017 were used to study the evolution of two newborn subdeltas of the Mississippi-Atchafalaya system, the Wax Lake Delta (WLD) and the Atchafalaya Delta (AD). The exposed delta areas derived from the satellite images using an unsupervised classification method were applied to evaluate the long-term land growth and seasonal area variations in the WLD and AD, as well as their main influencing factors. The results show that the land growth rate of the WLD decreased relative to the mean sea level from 1.67 km²/year to 0.35 km²/year from 1983–1999 to 1999–2017, and the growth rate of the AD decreased from 1.51 km²/year to 0.80 km²/year from 1973–1999 to 1999–2017. The land building of the two subdeltas during the 1980s to 1999 was more efficient than that from 1999 to 2017. The significant decreases in the land growth rate and land building efficiency are attributed both to the increased impact from relative sea level rise and to the decrease in river sediment discharge, and the extension of the distributary channels, as well. The satellite-derived exposed areas of the WLD and AD show unique seasonal loops affected by the growth of vegetation during the warmer weather from April to June and the decay of vegetation mainly due to the cold fronts in December, which is different from the monotonic changes in the areas of other deltas, mainly driven by the rise and fall of water levels. A new method based on the correction between the exposed areas and water levels from December to April was used to estimate the vertical growth rates of the WLD and AD. After deducting the relative sea level rise rate, the net sediment deposition rates of the WLD and AD were estimated to be 20.8 and 24.2 mm/year, respectively. Approximately 72% and 62% of the sediments deposited in the WLD and AD were used to offset the effects of relative sea level rise when building deltaic lands from 1999 to 2017. This study not only improves our understanding of the growth of newborn subdeltas but also aids in assessing whether river course shifts and sediment diversions can restore deltas or deltaic wetlands that are at risk of drowning.

1973年至2017年期间，共使用491张Landsat卫星图像研究了密西西比-阿查法拉雅系统的两个新生亚三角洲（蜡湖三角洲（WLD）和阿查法拉雅三角洲（AD））的演化。应用无监督分类法从卫星图像中获取的裸露三角洲面积，用于评估WLD和AD中的长期土地生长和季节性区域变化及其主要影响因素。结果表明，从1983-1999年到1999-2017年，WLD的土地增长率相对于平均海平面从1.67 km ² /年降低到0.35 km ² /年，AD的增长率从1.51 km降低² /年至0.80公里²/年，从1973–1999年到1999–2017年。1980年代至1999年这两个亚三角洲的土地建设比1999年至2017年的土地建设效率更高。土地增长率和土地建设效率的显着下降既归因于相对海平面上升的影响增加，也归因于下降河流中的泥沙排放，以及分流河道的延伸。WLD和AD的卫星衍生暴露区域显示出独特的季节循环，受4月至6月较暖天气期间植被的生长以及主要由于12月的冷锋造成的植被衰退的影响，这与单调变化不同在其他三角洲地区，主要是由于水位的上升和下降。使用一种基于12月至4月暴露区域和水位之间的校正的新方法来估算WLD和AD的垂直增长率。扣除相对海平面上升速度后，WLD和AD的净沉积物沉积速率分别估计为20.8和24.2 mm /年。WLD和AD中约有72％和62％的沉积物被用来抵消1999年至2017年建造三角洲土地时相对海平面上升的影响。这项研究不仅增进了我们对新生亚三角洲生长的理解，而且有助于评估河道的转移和沉积物的转移是否可以恢复有溺水危险的三角洲或三角洲湿地。扣除相对海平面上升速度后，WLD和AD的净沉积物沉积速率分别估计为20.8和24.2 mm /年。WLD和AD中约有72％和62％的沉积物被用来抵消1999年至2017年建造三角洲土地时相对海平面上升的影响。这项研究不仅增进了我们对新生亚三角洲生长的理解，而且有助于评估河道的转移和沉积物的转移是否可以恢复有溺水危险的三角洲或三角洲湿地。扣除相对海平面上升速度后，WLD和AD的净沉积物沉积速率分别估计为20.8和24.2 mm /年。WLD和AD中约有72％和62％的沉积物被用来抵消1999年至2017年建造三角洲土地时相对海平面上升的影响。这项研究不仅增进了我们对新生亚三角洲生长的理解，而且有助于评估河道的转移和沉积物的转移是否可以恢复有溺水危险的三角洲或三角洲湿地。