 |
|
|
|
|
|
|
Current Hydrographs Are Available for Wells in Every Pennsylvania Countyby Todd Giddings, Ph.D., P.G. Perhaps you have wondered just how much ground-water recharge has occurred in your local area due to the melting of last winter’s snow pack. Or, you may have gotten a phone call from someone who insists that their well is out of water due to a low water table, and you would like to know if the water-table levels in your area are currently declining. Thanks to a program funded in large part by the Pennsylvania Department of Environmental Protection, every county in Pennsylvania now has a monitoring well maintained by the US Geological Survey, and the hydrographs are available on the Web. These wells use satellite telemetry to send the water-table level data to the Web site every four hours, so the data you are looking at are called real-time data. The monitoring wells are listed alphabetically by county, and when you click the link, you see the current 7-day hydrograph for the well. The USGS Web address for ground-water (and surface-water) data throughout Pennsylvania is http://pa.water.usgs.gov/ . In the right column of this home page, under the heading Current Hydrologic Conditions in Pennsylvania, there is a link labeled Ground-Water Conditions, and this link will take you to the alphabetical listing of monitoring wells for each county. Click on the underlined well number for your county of choice, and you will see a 7-day hydrograph of that monitoring well, along with the Longitude and Latitude of the well, its total depth and construction characteristics, instrumentation that is installed, remarks, and the period of record available. You can type 31 into the Days box and then click get data to see the hydrograph for up to 31 days. If you want a hydrograph for a longer period of time, go to the blue bar at the top of the page that says: “Available data for this site”, and click the drop-down arrow, select Recent daily, and then click GO. Now you can enter a larger number of days into the Days box to see a hydrograph for a period of up to 548 days for the well. You need to keep in mind that these real-time water-table level data are provisional, and inaccuracies in the data may be present because of instrument malfunctions or physical changes at the measurement site. Subsequent review may result in significant revisions to the data. If you want a high-quality hydrograph that you can copy and paste into a document, click on Download a presentation-quality graph. If you want to know where in your county the monitoring well is located, again go to the blue bar at the top of the page that says: “Available data for this site”, and click the drop-down arrow, select Station site map, and then click GO. You will see both a Pennsylvania map of the well location, and a local map that will allow you to zoom in for a very detailed map of the well location. Because not all wells have been located by using a Global Positioning System instrument to get their exact longitude and latitude, some location maps show only the approximate well location. This example is a 548-day hydrograph of monitoring well CE 686 located two miles southwest of State College in Centre County. I selected a presentation-quality graph and then copied and pasted this hydrograph into the text of this article. This hydrograph shows that the water-table levels in the headwaters area of the Spring Creek Watershed are 60 feet higher than they were a year ago at this time. The very significant amount of ground-water recharge that has occurred in 2003 was due to snow melt that occurred slowly and so the melt water did not run off. The Invisible Drought (ground-water drought) that has impacted the Spring Creek Watershed for the past four years has been alleviated by the ground-water recharge that caused the water-table levels to rise 60 feet, but the water-table levels are not yet back to normal levels for this time of year.
|
|
