Domestic groundwater withdrawal rates from the Ozark Plateaus aquifer system, 1900 to 2010

Groundwater is an often overlooked freshwater resource compared to surface water, but groundwater is used widely across the United States, especially during periods of drought. If groundwater models can successfully simulate past conditions, they may be used to evaluate potential future pumping scenarios or climate conditions, thus providing a valuable planning tool for water-resource managers. Quantifying the groundwater-use component for a groundwater model is a vital but often challenging endeavor. This dataset includes groundwater withdrawal rates modeled for the Ozark Plateaus aquifer system (Ozark system) from 1900 to 2010 by county for domestic water use. Public supply, non-agriculture, livestock, and agriculture groundwater withdrawal rates are available in the complementary dataset “Public supply, non-agriculture, livestock, and agriculture groundwater withdrawal rates from the Ozark Plateaus aquifer system, 1900 to 2010”. The Ozark system is located in the central United States and is composed of interbedded Cambrian to Pennsylvanian clastic and carbonate lithologies. In stratigraphic order, the Ozark system includes the Basement confining unit, St. Francois aquifer, St. Francois confining unit, Ozark aquifer, Ozark confining unit, Springfield Plateau aquifer, and Western Interior Plains confining system. Generally, the lower portion of the Ozark aquifer is the primary source of groundwater across much of Missouri and the Springfield Plateau aquifer is used across northern Arkansas. A full description of the methods used to model groundwater withdrawal rates from the Ozark system are available in Knierim et al., IN PREP. Briefly, groundwater use was modeled by 1) acquiring site-specific and county-level groundwater withdrawal rates and well locations (with and without pumping information) from state agencies and the U.S. Geological Survey, 2) linearly interpolating groundwater withdrawal rates to create a yearly time-step for the period of observations (generally 1962 to 2010), 3) extrapolating county-level groundwater withdrawal rates to 1900 for domestic groundwater use assuming use was linearly related to population change, then constraining groundwater withdrawal rate to 0 million liters per day (ML/d) in 1900 using a multiplier that incrementally ranged from zero in 1900 to one in 2010, 4) attributing groundwater withdrawal rates to well locations using a hierarchical process where county-level groundwater withdrawal rates were disaggregated to wells where pumping was known to occur at any time, followed by county-level groundwater withdrawal rates disaggregated to well locations with a potential groundwater-use type based on land use, and 5) aggregation into model cells (row, column, layer) and county by summing modeled site-specific groundwater withdrawal rates using well location and depth. The large dataset (148,836 well locations) and long period (110 years) necessitated modeling groundwater use programmatically using Python 2.7.相较于地表水，地下水常被忽视，但却是美国广泛使用的淡水资源，在干旱时期尤为如此。若地下水模型能够精准模拟过往水文条件，便可用于评估未来抽水方案或气候情景，从而为水资源管理者提供极具价值的规划辅助工具。为地下水模型量化地下水使用组分是一项至关重要却常颇具挑战的工作。本数据集包含1900年至2010年奥扎克高原含水层系统（Ozark Plateaus aquifer system，简称奥扎克系统）按县域统计的生活用水地下水抽取速率模型结果。公共供水、非农业、畜牧业及农业地下水抽取速率数据可在配套数据集《奥扎克高原含水层系统1900-2010年公共供水、非农业、畜牧业及农业地下水抽取速率》中获取。奥扎克系统位于美国中部，由寒武纪至宾夕法尼亚纪的碎屑岩与碳酸盐岩互层岩性组成。按地层顺序，奥扎克系统包含基底隔水层、圣弗朗索瓦含水层、圣弗朗索瓦隔水层、奥扎克含水层、奥扎克隔水层、斯普林菲尔德高原含水层以及西部内陆平原隔水系统。总体而言，奥扎克含水层的下部是密苏里州大部分地区的主要地下水来源，而斯普林菲尔德高原含水层则为阿肯色州北部提供地下水。关于奥扎克系统地下水抽取速率建模方法的完整说明可参阅Knierim等人的待刊研究（IN PREP）。简言之，地下水使用量的建模流程如下：1）从各州政府机构及美国地质调查局（U.S. Geological Survey）获取点位特定及县域级的地下水抽取速率、水井位置（含抽水信息与无抽水信息两类）；2）对观测时段（通常为1962年至2010年）的地下水抽取速率进行线性插值，生成年度时间步长数据；3）假设生活用水量与人口变化呈线性相关，将县域级生活用水抽取速率外推至1900年，再通过一个1900年取值为0、2010年取值为1的递增乘数将1900年的地下水抽取速率约束为0万升/日（ML/d）；4）采用层级流程将地下水抽取速率分配至水井点位：先将县域级抽取速率拆解至已知曾发生抽水的水井，再将县域级抽取速率分配至基于土地利用确定潜在地下水使用类型的水井点位；5）依据水井位置与深度，将点位特定的建模抽取速率求和，聚合至模型网格单元（行、列、层）及县域尺度。本数据集规模庞大（涵盖148836个水井点位）且时间跨度长达110年，因此需通过Python 2.7编程实现地下水使用量的建模工作。