The regional aquifer system underlying the Northern Great Plains in parts of Montana, North Dakota, South Dakota, and Wyoming; summary

Abstract

The Northern Great Plains Regional Aquifer-System Analysis is the first of a series of planned nationwide regional geohydrologic studies. This summary is principally a graphic presentation of the major results of four basic facets of investigation designed to provide the best possible understanding of a large (about 300,000 square miles) and extremely complex groundwater flow system. The reader is encouraged to refer to subsequent volumes in this series for the details of treatment of components and of results of the study. The geologic framework within which the groundwater flow system operates has been defined. The study area basically consists of highland areas of sediment sources and basin areas of sediment deposition. The geologic investigation principally involved definition of the types of sediment (any rocks), the areal extent and thickness of sediment (any rocks), and the mechanisms that controlled deposition of the sediments. The spatial distribution of hydraulic pressure has been portrayed as potentiometric surfaces mapped for several aquifers. The implied groundwater flow system is one of recharge in and near the highland areas in the western and southwestern part of the study area and one of generally eastward and northeastward flow of ground water toward areas of discharge in Canada, North Dakota, and South Dakota. The distribution of chemical quality of the ground water has been defined with available data, and the mechanisms controlling changes in chemical quality have been interpreted. The chemistry of water from aquifers of Paleozoic through Mesozoic age is controlled by a variety of geochemical mechanisms, with dissolution of evaporites and mixing of water being dominant. Dedolomitization is a significant mechanism, and sulfate reduction and cation exchange are probably active mechanisms as well. The entire system of groundwater flow with all of its controlling factors has been defined as a conceptual model and has been simulated with a mathematical model. Five major aquifers have been defined and simulated, and the digital model has been used to interpret areas and rates of recharge, areas and rates of discharge, areas and rates of leakage, and rates and directions of flow. The model has been further used to simulate several hypothetical pumping alternatives to determine the cause-and-effect relationship between pumping, drawdown, and assumed conditions. CENTRAL HIGH PLAINS NEBRASKA EXPLANATION Jurassic and Triassic or older rocks exposed at the land surface Area of principally bicarbonate facies Area of principally sulfate facies Area of principally chloride facies Combinations of these numbers indicate order of dominant facies Modified from K.D. Peter, U.S. Geological Survey, written commun.. 1982 0 100 200 KILOMETERS FIGURE 37. Hydrochemical facies of water in the Lower Cretaceous aquifer system.

Post-Closure Performance Assessment for Deep Borehole Disposal of Cs/Sr Capsules

“…Regional hydraulic head gradients in the order of 0.001 m/m have been reported in deep sedimentary aquifers [19][20][21]. Site investigations were performed at Forsmark and Oskarshamn in Sweden in boreholes in fractured granite down to depths of about 1000 m. These site investigations yielded estimates of groundwater flow rates, transmissivities, and hydraulic head gradients [22].…”

Groundwater availability of the Williston Basin, United States and Canada

“…The Williston Basin is a sedimentary basin-a geologic bowl-like structure filled with layered sedimentary rocks. The basin is as deep as 10,000 feet (ft) and consists of Paleozoic, Mesozoic, and Cenozoic-age formations that overlie Precambrian-age rocks (Sandberg, 1962;Downey and Dinwiddie, 1988;Dolton and others, 1990). The basin is nationally important for the production of energy resources, spanning Montana, North Dakota, and South Dakota in the United States, and Manitoba and Saskatchewan in Canada (Thamke and others, 2014).…”

HYDROLOGICAL EFFECTS OF AN UNCONTROLLED FLOWING WELL, RED RIVER VALLEY, NORTH DAKOTA, USA1

“…These areas of ground water sapping and discharge have led to a 20 km wide band of saline soils in this part of the Red River Valley. Slow natural discharge continues through the glacial sediments at present (Downey and Dinwiddie, 1988;Gerla, 1992). Discharged ground water is strongly mineralized (total dissolved solids greater than 8,000 mg/l) and has a small SO 4 2to Clratio, compared to near surface ground water recharged directly from precipitation (Gerla, 1992).…”