Aquifer framework datasets used to represent the Southern Nevada volcanic-rock aquifers, Nevada

The Southern Nevada volcanic-rock aquifers reside in southern-central Nevada. This group of aquifers can be categorized into welded tuff, bedded tuff, and lava flow aquifers. Each of these categories possess different physical characteristics and have varying degrees of welding and number of interconnected joints. The lithology of these aquifers is primarily dependent on mode of eruption and cooling and are highly variable. Because the lithology is so variable, so is groundwater transmission, storage, and yield (HA 730-B).

This product provides source data for the Southern Nevada volcanic-rock aquifers framework, including: 
Extent shapefiles: 
1. p_57SRNVDV.shp: Polygon shapefile containing the areal extent of the Southern Nevada volcanic-rock aquifers (SRNVDV_AqExtent). The extent file contains no aquifer subunits.

Altitude raster files:  
1. ra_57SRNVDV_top.tif: Altitude raster dataset of the top of the Southern Nevada volcanic-rock aquifers. The altitude values are in meters reference to North American Vertical Datum of 1988 (NAVD88). This data was sourced from Sweetkind and others, 2011. 
2. ra_57SRNVDV_bot.tif: Altitude raster dataset of the bottom of the Southern Nevada volcanic-rock aquifers. The altitude values are in meters reference to NAVD88. This data was sourced from Sweetkind and others, 2011. 

Depth raster files: 
1. rd_57SRNVDV_top.tif: Depth raster dataset of the top of the Southern Nevada volcanic-rock aquifers. The depth values are in meters below land surface (NED, 100-meter).
2. rd_57SRNVDV_bot.tif: Depth raster dataset of the bottom of the Southern Nevada volcanic-rock aquifers. The depth values are in meters below land surface (NED, 100-meter).

南内华达州火山岩含水层分布于内华达州中南部区域。该类含水层可划分为熔结凝灰岩、层状凝灰岩以及熔岩流含水层三大类别。各类含水层具备独特的物理特性，且熔结程度与连通节理数量均存在显著差异。此类含水层的岩性主要受喷发方式与冷却过程控制，空间变异性极强。正因岩性差异显著，地下水的导水性能、储水性能与涌水量也随之呈现较大波动（HA 730-B）。

本数据集为南内华达州火山岩含水层框架提供源数据，具体包含以下内容：
1. 范围形状文件（shapefile）：
1. p_57SRNVDV.shp：包含南内华达州火山岩含水层（SRNVDV_AqExtent）平面分布范围的多边形形状文件，该范围文件未包含含水层子单元。
2. 高程栅格文件（raster）：
1. ra_57SRNVDV_top.tif：南内华达州火山岩含水层顶板高程栅格数据集，高程值以1988年北美垂直基准面（North American Vertical Datum of 1988, NAVD88）为基准，单位为米。该数据源自Sweetkind等人2011年的研究成果。
2. ra_57SRNVDV_bot.tif：南内华达州火山岩含水层底板高程栅格数据集，高程值以NAVD88为基准，单位为米。该数据源自Sweetkind等人2011年的研究成果。
3. 深度栅格文件（raster）：
1. rd_57SRNVDV_top.tif：南内华达州火山岩含水层顶板埋深栅格数据集，埋深值以地表为基准（基于100米分辨率的国家高程数据集（National Elevation Dataset, NED）），单位为米。
2. rd_57SRNVDV_bot.tif：南内华达州火山岩含水层底板埋深栅格数据集，埋深值以地表为基准（基于100米分辨率的NED），单位为米。