Land-Surface Processes, Dust Sources, and Particulate Fluxes of the 1930s Dust Bowl Drought in the U.S. Great Plains

这项研究项目将评估农业做法是否像过去80年所假定的那样，是造成1930年代沙尘暴干旱期间风蚀和全大陆沙尘暴的主要原因。该项目将为北美中部开发一个新的数据库，以评估20世纪30年代沙尘暴旱灾的风蚀和粉尘排放估计的自然和人为地表过程的空间和时间变异性。该项目将产生新的量化标准，以评估耕作、随后的重新耕作以及自然和人类相关过程之间的相互作用，这些过程导致1930年代风沙沉积和景观剥蚀重新激活。该数据库将提供适当的空间尺度，以便估算受干旱影响的表面的尘埃发射率以及尘埃对区域和全球大气颗粒物负荷的潜在贡献。许多地球系统模型强调了21世纪大平原在极端干旱面前的脆弱性，干旱有可能超过20世纪30年代的条件，从而增加了风沙活动加剧的可能性。该项目加强了对1930年代干旱期间沙尘产生的时空变异性的理解，这将改进大气-陆地相互作用模式的参数化。对这些复杂动力学知识的改进将为如何更好地缓解大气粉尘负荷的增加提供见解，大气粉尘负荷的增加会增加过早死亡的风险，并增加呼吸道、心血管和粉尘传播病毒疾病的发病率。为了评估植被、相关的风过程以及沙尘源和沙尘通量的变化，研究人员将分析1936年至1939年的航空摄影。目标区域将包括德克萨斯州和俄克拉何马州狭长地带的持续干旱地区，堪萨斯州、科罗拉多州和新墨西哥州的邻近地表；以及内布拉斯加州西部沙丘和北达科他州西部的其他潜在尘源地区。调查人员将在图像分析表明沙子和其他被风吹起的颗粒在20世纪30年代积累的地点进行实地研究，从而深入了解沙尘暴沉积的厚度、连续性和颗粒大小。一系列粉尘排放估计将根据分类的地表分布和对美国西部类似地表粉尘产生和释放的经验分析得出。这些粉尘释放估计将使用便携式现场风蚀实验室对土壤粉尘通量的新现场测量进行评估。

This research project will evaluate whether agricultural practices were the dominant cause for wind erosion and continent-wide dust storms during the 1930s Dust Bowl drought as has been assumed for the past 80 years. The project will develop a new database for central North America to assess the spatial and temporal variability of natural and human-induced surface processes on wind erosion and dust emission estimates for the 1930s Dust Bowl drought. The project will yield new quantitative criteria to evaluate the role of cultivation, subsequent re-plowing, and the interactions among natural and human-related processes that led to reactivation of antecedent aeolian deposits and landscape denudation in the 1930s. This database will provide appropriate spatial-scaling for deriving estimates of dust emissivity from drought-stricken surfaces and the potential contributions of dust to regional and global atmospheric particulate loads. Many Earth system models underscore the vulnerability of the Great Plains in the 21st century to extreme droughts, with drying having the potential to exceed conditions in the 1930s, thereby increasing the potential for heightened aeolian activity. The enhanced understanding provided by this project of the spatial and temporal variability in dust generation during the 1930s drought will improve parameterization of atmosphere-land interaction models. Improvements in knowledge of these complex dynamics will provide insights regarding how to better mitigate against increases in atmospheric dust loads, which pose with increased risks of premature mortality and morbidity from respiratory, cardiovascular, and dust-borne viral diseases.To assess changes in vegetation, associated wind processes, and dust sources and fluxes the heart of the Dust Bowl on the Great Plains, the investigators will analyze aerial photography from 1936 and 1939. Targeted regions will include persistent drought areas in the Texas and the Oklahoma panhandles, adjacent surfaces in Kansas, Colorado, and New Mexico; and other potential dust sources areas in the western Nebraska sand hills and in western North Dakota. The investigators will conduct field-based studies at sites where analysis of images indicates that sand and other wind-blown particles accumulated in the 1930s, thereby providing insights into thickness, continuity and particle sizes of Dust Bowl deposits. A range of dust emission estimates will be derived from the distribution of classified land-surfaces and from empirical analyses of dust production and release for analogous surfaces in the western U.S. These dust release estimates will be evaluated with new field measurements of dust flux from soils with the use of the portable in situ wind erosion lab.