Texas A&M AgriLife Research and Extension Center, P.O. Box 1658, Vernon, TX 76385, United States.
Texas A&M AgriLife Research and Extension Center, P.O. Box 1658, Vernon, TX 76385, United States.
Sci Total Environ. 2014 Aug 15;490:379-90. doi: 10.1016/j.scitotenv.2014.05.013. Epub 2014 May 24.
Rapid groundwater depletion has raised grave concerns about sustainable development in many parts of Texas, as well as in other parts of the world. Previous hydrologic investigations on groundwater levels in Texas were conducted mostly on aquifer-specific basis, and hence lacked state-wide panoramic view. The aim of this study was to present a qualitative overview of long-term (1930-2010) trends in groundwater levels in Texas and identify spatial patterns by applying different statistical (boxplots, correlation-regression, hierarchical cluster analysis) and geospatial techniques (Moran's I, Local Indicators of Spatial Association) on 136,930 groundwater level observations from Texas Water Development Board's database. State-wide decadal median water-levels declined from about 14 m from land surface in the 1930s to about 36 m in the 2000s. Number of counties with deeper median water-levels (water-level depth>100 m) increased from 2 to 13 between 1930s and 2000s, accompanied by a decrease in number of counties having shallower median water-levels (water-level depth<25 m) from 134 to 113. Water-level declines across Texas, however, mostly followed logarithmic trends marked by leveling-off phenomena in recent times. Assessment of water-levels by Groundwater Management Areas (GMA), management units created to address groundwater depletion issues, indicated hotspots of deep water-levels in Texas Panhandle and GMA 8 since the 1960s. Contrasting patterns in water use, landcover, geology and soil properties distinguished Texas Panhandle from GMA 8. Irrigated agriculture is the major cause of depletion in the Texas Panhandle as compared to increasing urbanization in GMA 8. Overall our study indicated that use of robust spatial and statistical methods can reveal important details about the trends in water-level changes and shed lights on the associated factors. Due to very generic nature, techniques used in this study can also be applied to other areas with similar eco-hydrologic issues to identify regions that warrant future management actions.
地下水的快速枯竭引起了人们对德克萨斯州乃至世界其他地区可持续发展的严重关注。以前在德克萨斯州进行的地下水水位水文调查主要是基于含水层的具体情况进行的，因此缺乏全州范围内的全景图。本研究的目的是通过应用不同的统计（箱线图、相关回归、层次聚类分析）和地理空间技术（Moran's I、局部空间关联指标）对德克萨斯州水资源委员会数据库中的 136930 个地下水观测值，对德克萨斯州地下水水位的长期（1930-2010 年）趋势进行定性概述，并确定空间格局。全州范围内，20 世纪 30 年代至 2000 年代，地下水水位的十年中位数从离地表约 14 米下降到约 36 米。地下水水位深度>100 米的县的数量从 1930 年代的 2 个增加到 2000 年代的 13 个，而地下水水位深度<25 米的县的数量从 134 个减少到 113 个。然而，德克萨斯州的水位下降大多遵循对数趋势，最近出现了平稳化现象。通过地下水管理区（GMA）对水位进行评估，GMA 是为解决地下水枯竭问题而创建的管理单位，这表明自 20 世纪 60 年代以来，德克萨斯州狭长地带和 GMA8 地区的水位较深。德克萨斯州狭长地带与 GMA8 的用水、土地覆盖、地质和土壤特性形成鲜明对比。与 GMA8 不断增加的城市化相比，灌溉农业是导致德克萨斯州狭长地带地下水枯竭的主要原因。总的来说，我们的研究表明，使用强大的空间和统计方法可以揭示水位变化趋势的重要细节，并阐明相关因素。由于本研究采用的技术具有非常通用的性质，因此也可以应用于具有类似生态水文问题的其他地区，以确定需要未来管理措施的区域。
