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DGS Annual Report

DGS Annual Report of Programs and Activities.

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Site content related to keyword: "hazards"

Geologic Map Day - October 16, 2015

Geologic Map Day 2015, a special event designed to promote awareness of geologic mapping and its vital importance to society.

Delaware Geological Survey issues report on groundwater modeling in eastern Sussex County

The Delaware Geological Survey (DGS) has released a new technical report titled Simulation of Groundwater Flow and Contaminant Transport in Eastern Sussex County, Delaware with Emphasis on Impacts of Spray Irrigation of Treated Wastewater, which was prepared by Changming He and A. Scott Andres of DGS.

DGS Report of Investigations No. 79 documents development of a detailed study of subsurface hydrogeology, interactions between aquifers and streams, and the effects of spray irrigation of treated wastewater on groundwater beneath southern eastern Sussex County.

RI79 Simulation of Groundwater Flow and Contaminant Transport in Eastern Sussex County, Delaware With Emphasis on Impacts of Spray Irrigation of Treated Wastewater

Simulation of Groundwater Flow and Contaminant Transport in Eastern Sussex County, Delaware With Emphasis on Impacts of Spray Irrigation of Treated Wastewater

This report presents a conceptual model of groundwater flow and the effects of nitrate (NO3-) loading and transport on shallow groundwater quality in a portion of the Indian River watershed, eastern Sussex County, Delaware. Three-dimensional, numerical simulations of groundwater flow, particle tracking, and contaminant transport were constructed and tested against data collected in previous hydrogeological and water-quality studies.

The simulations show a bimodal distribution of groundwater residence time in the study area, with the largest grouping at less than 10 years, the second largest grouping at more than 100 years, and a median of approximately 29 years.

Historically, the principal source of nitrate to the shallow groundwater in the study area has been from the chemical- and manure-based fertilizers used in agriculture. A total mass of NO3- -nitrogen (N) of about 169 kg/day is currently simulated to discharge to surface water. As the result of improved N-management practices, after 45 years a 20 percent decrease in the mass of NO3- -N reaching the water table would result in an approximately 4 percent decrease in the mass of simulated N discharge to streams. The disproportionally smaller decrease in N discharge reflects the large mass of N in the aquifer coupled with long groundwater residence times.

Currently, there are two large wastewater spray irrigation facilities located in the study domain: the Mountaire Wastewater Treatment Facility and Inland Bays Wastewater Facility. The effects of wastewater application through spray irrigation were simulated with a two-step process. First, under different operations and soil conditions, evaporation and water flux, NO3- -N uptake by plants, and NO3- -N leaching were simulated using an unsaturated flow model, Hydrus-1D. Next, the range of simulated NO3- -N loads were input into the flow and transport model to study the impacts on groundwater elevation and NO3- -N conditions.

Over the long term, the spray irrigation of wastewater may increase water-table elevations up to 2.5m and impact large volumes of groundwater with NO3-. Reducing the concentration of NO3- in effluent and increasing the irrigation rate may reduce the volumes of water impacted by high concentrations of NO3-, but may facilitate the lateral and vertical migration of NO3-. Simulations indicate that NO3- will eventually impact deeper aquifers. An optimal practice of wastewater irrigation can be achieved by adjusting irrigation rate and effluent concentration. Further work is needed to determine these optimum application rates and concentrations.

Stream and Tide Gage Data for Hurricane Sandy

GOES Satellite Image of Hurricane Sandy (Image provided by NASA)

Hurricane Sandy was a major storm event for the tidal areas of Delaware. As a part of the mission of the Delaware Geological Survey, we have compiled preliminary data related to Delaware tide and stream levels related to the Hurricane Sandy and compared them with previous flooding records.

The Storm of '62

Kelvin Ramsey was quoted in the special section of Coastal Point, which featured the 50th anniversary of the Ash Wednesday 1962 nor'easter

DGS honors retiring director, state geologist Talley

Talley is retiring after 38 years of service

John Talley joined the Delaware Geological Survey as a project geologist in 1972, became a senior scientist and hydrogeologist by 1986, and rose to director and state geologist by 2004. He’s consulted with dozens of university, state, and federal governments and groups and amassed a list of more than 50 publications and reports.

Stefanie Baxter interviewed by local media regarding earthquake in Japan.

Stefanie Baxter, research associate with the Delaware Geological Survey, was interviewed March 11 by Channel 6 Action News, Channel 16 WBOC and the News Journal, regarding the 8.9 magnitude earthquake in Japan.

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DGS releases new geologic map of Rehoboth Beach area

The Delaware Geological Survey (DGS) has published a new geologic map of the Rehoboth Beach area in eastern Sussex County entitled Geologic Map of the Fairmount and Rehoboth Beach Quadrangles, Delaware. Geologic Map 16 presents the results of research by Kelvin W. Ramsey of the DGS.

Chances of large Delmarva quake 'are very remote'

Stefanie Baxter was quoted in an article in the News Journal, and commented on earthquakes in Delaware.

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USGS Real-time Earthquakes Map

Maps and resources for real-time M1+ earthquakes.

DGS Digital Datasets

In the same ways as our printed publications, digital data released by the DGS represent the results of original professional research and as such are used by professionals and the public.

Catalog of Delaware Earthquakes Spreadsheet

Catalog of Delaware Earthquakes Spreadsheet

The occurrences of earthquakes in northern Delaware and adjacent areas of Pennsylvania, Maryland, and New Jersey are well documented by both historical and instrumental records. Over 550 earthquakes have been documented within 150 miles of Delaware since 1677. One of the earliest known events occurred in 1737 and was felt in Philadelphia and surrounding areas. The largest known event in Delaware occurred in the Wilmington area in 1871 with an intensity of VII (Modified Mercalli Scale). The second largest event occurred in the Delaware area in 1973 (magnitude 3.8 and maximum Modified Mercalli Intensity of V-VI). The epicenter for this event was placed in or near the Delaware River. Sixty-nine earthquakes have been documented or suspected in Delaware since 1871.

Investigating the Causes of Earthquakes in Delaware

Presentation on Investigating the Causes of Earthquakes in Delaware

Interactive Map of Delaware Earthquakes

Map and data listing of all earthquakes with an epicenter within the State of Delaware.

OFR18 A Numerical Indicator of Water Conditions for Northern Delaware

OFR18 A Numerical Indicator of Water Conditions for Northern Delaware

Numerical indicators, or indices, are widely used to measure the status of complex relationships. As such, indices have become accepted by researchers and the public in such disparate fields as economics, air quality, and weather. In this paper we explore the formulation of an indicator of water conditions in northern Delaware, propose formulas that may be applicable, and test those proposals against long-term records of basic data. The need for a simple indicator of water supply conditions in Delaware, and especially in New Castle County, has become increasingly apparent. The Delaware River Basin Commission (DRBC) has applied an index to the Delaware River Basin, which includes a portion of Delaware. The Governor's Drought Advisory Committee has sought an objective means of determining when water supply conditions might warrant conservation measures. Discussions of the subject have also been held within the State Comprehensive Water Management Committee. We are pleased to acknowledge the constructive comments of these groups and of other colleagues with whom we have discussed this work. George R. Phillips of the Delaware Department of Natural Resources and Environmental Control (DNREC) was especially helpful in analyzing the practical implications of using the index presented in this paper. John R. Mather, Delaware State Climatologist, provided Palmer Drought Severity Index values with the cooperation of the National Weather Service. This report was reviewed by Richard N. Benson and John H. Talley of the Delaware Geological Survey (DGS).

Earthquake rattles New Jersey and Delaware

Earthquake reported July 1 (credit NBC News 10)

A minor earthquake occurred near Pennsville, N.J., at 9:44 a.m., Wednesday, July 1, according to the Delaware Geological Survey (DGS) at the University of Delaware. The earthquake, which had a magnitude of 2.8, was recorded at the three northern stations of the DGS seismic network.

Earth's shift rattles state, some nerves - Centered in N.J., quake sounded like a loud noise

Delaware Geological Survey geologist, Stefanie Baxter shows the seismic recordings from detectors Wednesday.

When the earthquake hit a little before 10 a.m., everyone who heard the crack and felt the ground rumble thought something had exploded or crashed. Chimneys fell over, windows shattered, people panicked -- on Oct. 9, 1871. The magnitude 4.1 earthquake that shook Wilmington that morning -- the most intense temblor ever recorded in Delaware -- easily outshook the magnitude 2.8 quake that hit the state Wednesday morning.

Overview of Earthquakes in Delaware

DGS Seismic Recorder

Earthquakes occur in northern Delaware and adjacent areas of Pennsylvania, Maryland, and New Jersey. Over 550 earthquakes have been documented within 150 miles of Delaware since 1677, and 69 earthquakes have been documented or suspected in Delaware since 1871.