Cooperative Agricultural Research Center, College of Agriculture and Human Sciences, Prairie View A&M University, Prairie View, TX 77446, USA.
Cooperative Agricultural Research Center, College of Agriculture and Human Sciences, Prairie View A&M University, Prairie View, TX 77446, USA.
Sci Total Environ. 2022 Aug 20;835:155336. doi: 10.1016/j.scitotenv.2022.155336. Epub 2022 Apr 19.
Texas ranks first in the United States in the variety and frequency of most natural disasters, such as flooding, wildfires, hurricanes, winter storms, and droughts. In February 2021, the winter storm named Uri caused an abnormal decline in the air temperature in the southcentral United States, notably in Texas. Right before Uri, most of Texas was going through a drought spell. Thus, this study analyzed how Uri influenced the drought severity, soil profile moisture content, and vegetation cover (Normalized Difference Vegetation Index, NDVI) across Texas. Data used in this analysis was obtained from the web-based geospatial applications gridMET and Crop-CASMA. The collected datasets include the Palmer Drought Severity Index (PDSI), Snow Water Equivalent (SWE), soil moisture, and NDVI at different spatial resolutions. These datasets were aggregated to the county scale using the zonal statistics analysis. The strength of the correlation between SWE and soil moisture was quantified based on the Pearson correlation coefficient. The percentage change in live vegetation cover due to the impact of the frigid temperature and snow coverage across the state was quantified by analyzing the average weekly NDVI before and after the winter storm. There was a reasonably strong correlation between the SWE contribution of Uri and the increase of the rootzone soil moisture (Pearson's r = 0.42). Similarly, the SWE showed a higher correlation with daily rootzone soil moisture with a Pearson's correlation coefficient of 0.49 on March 1. Furthermore, our results revealed a reduction in the NDVI values to less than 0.60 across Texas during the third week of February. Overall, Texas NDVI values seriously decreased due to Uri. Despite its disruptive effects on the state infrastructures and the economy, Uri snow lessened the drought conditions relatively for a short time.
德克萨斯州在各种自然灾害的种类和频率方面位居美国第一，这些灾害包括洪水、野火、飓风、冬季风暴和干旱等。2021 年 2 月，一场名为“乌里”的冬季风暴导致美国中南部地区，尤其是德克萨斯州的气温异常下降。在“乌里”之前，德克萨斯州的大部分地区正经历干旱。因此，本研究分析了“乌里”如何影响德克萨斯州的干旱严重程度、土壤剖面湿度和植被覆盖（归一化差异植被指数，NDVI）。本分析中使用的数据来自基于网络的地理空间应用程序 gridMET 和 Crop-CASMA。收集的数据集包括 Palmer 干旱严重指数（PDSI）、雪水当量（SWE）、土壤湿度和不同空间分辨率的 NDVI。使用区域统计分析将这些数据集汇总到县一级。根据皮尔逊相关系数量化 SWE 和土壤湿度之间的相关性强度。通过分析冬季风暴前后每周的平均 NDVI，量化由于全州寒冷温度和积雪覆盖对活体植被覆盖的影响而导致的百分比变化。“乌里”的 SWE 贡献与根区土壤湿度的增加之间存在相当强的相关性（皮尔逊 r=0.42）。同样，SWE 与每日根区土壤湿度的相关性更高，3 月 1 日的皮尔逊相关系数为 0.49。此外，我们的研究结果表明，在 2 月的第三周，德克萨斯州的 NDVI 值降至 0.60 以下。总的来说，由于“乌里”，德克萨斯州的 NDVI 值严重下降。尽管它对该州的基础设施和经济造成了破坏性影响，但“乌里”的雪在短时间内相对减轻了干旱状况。
