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.

With increases in computational power and capabilities of software, numerical models have become state-of-the-practice for characterization of groundwater flow and contaminant transport and water-resources management.

This report documents the results of a study in which a three-dimensional numerical model was used to simulate groundwater flow and quality in in the Columbia, Pocomoke and Manokin aquifers and intervening confining beds.

In addition to providing a focus for compilation of existing hydrogeologic information, the model simulates groundwater levels, flow directions, impacts of pumping wells, movement of nitrogen from land surface to the water table under different land uses and management scenarios, and transport of nitrate through shallow aquifers over many decades.

This information is needed to support planning of future water supplies and wastewater disposal and management of water-dependent environmental resources.

Simulations confirm field observations that show that nitrate contamination introduced in the 1970s are still resident in the aquifer and will require many decades to flush out even if nitrate inputs are reduced or stopped today.

The report fulfills part of the DGS’s mission to understand hydrologic systems and to advise, inform, and educate Delawareans about the results of such investigations for use in such topics as water resources, agriculture, public health, economic development, land-use planning, geologic hazards, environmental protection, energy and mineral resources, emergency management, and recreation.