CalGW Update 2020 - GW Change in Storage (2006-2018)
The CalGW Update 2020 - GW Change in Storage (2006-2018) is a zip file containing 1 shapefile and 1 excel file.
The shapefile, Reporting_Area_CV.shp, was used for the Bulletin 118 analysis for change in stored groundwater and shows the areas per Central Valley Hydrologic Region that are within a reporting area and outside of a reporting area. Reporting Area was found by creating a polygon around the extents of monitoring wells in DWR's Enterprise Water Management Database. The area in acres was force-calculated using the Shape_Area (in square meters) multiplied by 0.000247105, which is the square meters to acres conversion. This shapefile was used to create Figure 6-8 and Table 6-2.
The excel file, Chap6_Statewide_Change_In_Storage, is a compiled dataset based on a series of queries from the DWR Enterprise Water Management Database. Annual changes in stored groundwater were estimated using annual spring groundwater level data from wells within the Central Valley. For each year from 2010 through 2018, an annual dataset of groundwater elevation points in the Central Valley was created. Using the annual spring groundwater level datasets, annual change-point datasets were created by calculating the difference in groundwater elevation at “like points” (wells measured during both monitoring periods) over each one-year time period. The calculated elevation difference at each of these monitoring points represents the total change in groundwater elevation that occurred between the two monitoring periods at that well. Eight change-point datasets were created, representing the groundwater level changes from 2010 to 2011, 2011 to 2012, 2012 to 2013, 2013 to 2014, 2014 to 2015, 2015 to 2016, 2016 to 2017, and 2017 to 2018. Each annual change-point dataset was then used to construct a triangulated irregular network “change surface” with GIS tools. Each change surface is an interpolated three-dimensional representation of the total volume of space between early and late groundwater elevation values for each time period analyzed. To obtain the change in stored groundwater estimates, the total volumes estimated from each annual change surface was multiplied by the low and high specific-yield values (0.07 and 0.17, respectively). This dataset was used to create Table 6-3, and Figures 6-9, 6-10, 6-11, and 6-12.
Source: California's Groundwater Update 2020 (Bulletin 118)
About this Resource
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Name | CalGW Update 2020 - GW Change in Storage (2006-2018) |
Format | Zip File |
License | License not specified |
Created | 1 year ago |
Media type | application/zip |
has views | False |
id | 3ab3bacc-e263-423d-b340-f5ad0d63d24f |
metadata modified | 1 year ago |
package id | 292a4f68-2413-4c36-b12e-3ee5121cbbfc |
position | 33 |
state | active |