Final Project

Investigation of groundwater level changes within the bosque above and below the Alameda Drinking Water Diversion Dam

This project aims towards understanding how and if the diversion dam, installed in 2005, has had an effect on the levels of groundwater within the bosque surrounding the dam. My prediction was the groundwater levels would increase above the dam because water pools behind the dam, and downstream groundwater levels would decline. Data used for this project was obtained from the Bosque Ecosystem Monitoring Program (BEMP). www.bosqueschool.org/bemp./aspx

The Bosque Ecosystem Monitoring Program has 29 monitoring sites the bosque throughout New Mexico, primarily in the Middle Rio Grande. The organization collects variety of biotic and abiotic data in order to understand how the bosque is changing over time. The data is used by a variety of federal, state, city, and local agencies to assist in management decisions. Six of the BEMP sites were used for this project, they were Bobcat, Badger, Minnow, Diversion, Calabacillas, and Alameda. Two of these sites, Bobcat and Badger are above the diversion dam and the remaining sites are downstream from the dam.

The difference in mean annual depth to groundwater was calculated for all five wells at each BEMP site and was entered into ArcMap 10.1 for analysis. The Interpolation tool from the Spatial Analyst toolbox was used to create a series of images displaying the change in depth to groundwater since the dam installation in 2005-2012. The Spline method of interpolation was used per recommendation by Su Zhang, UNM GIS expert. The series of interpolations can be seen below.

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*negative values indicate an increase in groundwater level

There is a high degree of variability between each image, which makes it difficult to determine any particular overall trend in groundwater level changes. In order to delve into the groundwater level changes on a more detailed basis, one site above the dam (Badger), and one site below the dam (Alameda) were chosen and interpolations were performed on their data every other month for the same period of record. The series of interpolations can be seen below.

Alameda BEMP site Interpolations from 2005-2012

No significant trends can drawn from the series of interpolations shown below. Excel graphs showing the data reveal seasonal trends, however no overall shift in groundwater can be determined throughout this period of record.