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

该研究项目将评估农业实践是否如过去80年所假定的那样，是20世纪30年代沙尘暴干旱期间风蚀和大陆范围沙尘暴的主要原因。该项目将为北美中部建立一个新的数据库，以评估自然和人为引起的风蚀地表过程的空间和时间变异性，以及对1930年代沙尘碗干旱的沙尘排放估计。该项目将产生新的定量标准，以评估耕作、随后的复耕以及自然和人类相关过程之间的相互作用，这些过程导致了20世纪30年代以前的风沙沉积和景观剥蚀的重新激活。该数据库将提供适当的空间尺度，以估算干旱地表的沙尘发射率以及沙尘对区域和全球大气微粒负荷的潜在贡献。许多地球系统模型都强调了21世纪大平原对极端干旱的脆弱性，干旱有可能超过20世纪30年代的情况，从而增加了风成活动加剧的可能性。本项目对20世纪30年代干旱期间沙尘产生的时空变异性的进一步了解将改进大气-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减轻大气粉尘负荷的增加提供见解，因为大气粉尘负荷增加了因呼吸道、心血管和粉尘传播的病毒性疾病而过早死亡和发病的风险。为了评估植被的变化，相关的风过程，以及大平原沙尘暴中心的粉尘来源和通量，研究人员将分析1936年和1939年的航空照片。目标地区将包括德克萨斯州和俄克拉荷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区；在内布拉斯加州西部的沙丘和北达科他州西部的其他潜在粉尘源地区。研究人员将在一些地点进行实地研究，在那里，对图像的分析表明，20世纪30年代，沙子和其他被风吹来的颗粒积聚在那里，从而深入了解沙尘暴沉积物的厚度、连续性和颗粒大小。将从分类陆地表面的分布和对美国西部类似表面的粉尘产生和释放的经验分析中得出一系列粉尘排放估计。这些粉尘释放估计将通过使用便携式原位风蚀实验室对土壤粉尘通量进行新的现场测量来评估。

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.