Location of virtual wells used for urban (municipal and industrial use) pumpage in the Central Valley Hydrologic Model (CVHM)

This digital dataset contains the virtual wells used for urban (municipal and industrial use) pumpage for the Central Valley Hydrologic Model (CVHM). The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the U.S. Geological Survey (USGS) numerical modeling code MODFLOW-FMP (Schmid and others, 2006). This application is referred to here as the CVHM (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The total active modeled area is 20,334 square-miles on a finite difference grid comprising 441 rows and 98 columns. Slightly less than 50 percent of the cells are active. The CVHM model grid has a uniform horizontal discretization of 1x1 square mile and is oriented parallel to the valley axis, 34 degrees west of north (Faunt, 2009). Groundwater pumpage is a major part of the groundwater budget of the Central Valley, and is grouped into two categories for this study: agricultural and urban (which includes municipal and industrial sources). Urban wells were simulated as multi-node wells (Halford and Hanson, 2002) (Faunt, 2009; fig. C3). In each WBS, a single well was placed in each model cell where the predominant land use for a given time frame was urban. Because the extent of urban areas changes through time, wells were added and deleted accordingly in the model during the simulation period. In general, agricultural wells were replaced by urban wells in the model as the land use changed from agricultural to urban. The single well per model cell represents the composite of all wells in each square-mile cell and is referred to here as a virtual well. The CVHM is the most recent regional-scale model of the Central Valley developed by the USGS. The CVHM was developed as part of the USGS Groundwater Resources Program (see "Foreword", Chapter A, page iii, for details).

本数字数据集包含用于中央谷水文模型（Central Valley Hydrologic Model, CVHM）城市（市政与工业用途）抽水的虚拟井。加利福尼亚州境内的中央谷区域总面积约5万平方千米。中央谷复杂的水文系统采用美国地质调查局（U.S. Geological Survey, USGS）的数值模拟代码MODFLOW-FMP进行模拟（Schmid等，2006）。本模型在此简称CVHM（Faunt，2009）。借助MODFLOW-FMP，CVHM于1961—2003年间按月模拟中央谷内的地下水与地表水径流、灌溉农业、地面沉降及其他关键水文过程。该模型采用由441行、98列组成的有限差分网格，总有效模拟面积为20334平方英里，其中略少于50%的网格单元为有效单元。CVHM的模型网格采用统一的1×1平方英里水平离散精度，网格走向与谷轴平行，为北偏西34度（Faunt，2009）。地下水抽水是中央谷地下水收支的重要组成部分，本研究将其划分为两类：农业抽水与城市抽水（含市政与工业取水来源）。城市井以多节点井的形式进行模拟（Halford与Hanson，2002；Faunt，2009；图C3）。在每个WBS中，若某一模型网格单元在特定时段内的主导土地利用类型为城市用地，则在该单元内设置一口单井。由于城市区域范围随时间动态变化，模拟期内模型会据此增减虚拟井的数量。总体而言，当土地利用类型由农业用地转为城市用地时，模型中的农业井会相应替换为城市井。每个模型网格单元内的单井代表该平方英里单元内所有实际水井的集合体，本文中将其称为虚拟井。CVHM是美国地质调查局（USGS）开发的最新中央谷区域尺度水文模型。CVHM是美国地质调查局地下水资源计划的组成部分（详细信息参见"Foreword"，A章，第iii页）。