Geology topics

Donald I. Siegel

Publications and source records attributed to Donald I. Siegel.

12 recordsLinked to original sources

USGS2021

Review: “Jacob’s Zoo”— How using Jacob’s method for aquifer testing leads to more intuitive understanding of aquifer characteristics

The interpretation of aquifer responses to pumping tests is an important tool for assessing aquifer geometry and properties, which are critical in the assessment of water resources or in environmental remediation. However, the responses of aquifers, measured by time-drawdown relationships in monitoring wells, are nonunique solutions that are affected by many factors. Jacob’s Zoo is a collection of graphical interpretations that allows students and practitioners to develop an intuitive feel for how natural hydrogeological systems work, and develop a set of skills that provide a better understanding of aquifer properties far beyond interpretation of pumping tests. Jacob’s Zoo, based on the work of Jacob (1950), fosters a deeper understanding, although few practitioners realize the full utility of the method. Jacob CE (1950) Flow of groundwater, In: Rouse H (ed) Engineering Hydraulics, Wiley, New York. P 321–386.

Hydrogeology Journal↗

USGS2018

Using halogens (Cl, Br, I) to understand the hydrogeochemical evolution of drought-derived saline porewater beneath a prairie wetland

Numerous closed-basin prairie wetlands throughout the Prairie Pothole Region (PPR) of North America maintain moderate surface pond salinities (total dissolved solids [TDS] from 1 to 10 g L − 1 ) under semiarid climate by accumulation of gypsum and saline lenses of sulfate-rich porewater (TDS > 10 g L − 1 ) in wetland sediments during droughts. In order to understand the hydrogeochemical origin and composition of these saline porewaters, we made a detailed geochemical survey of Cl − , SO 4 2 − , Br, and I in the porewater, pondwater, and upland groundwater of a typical closed-basin prairie wetland (P1 in the Cottonwood Lake study area, North Dakota). Concentrations of Cl − ranged up to 5.9 mM in the saline porewaters, and was strongly correlated with SO 4 2 − and Br (Pearson's r > 0.7, p < 0.05; concentrations ranging up to 131 mM and 39 μM, respectively) due to the conservative effects of surface water evaporation. In contrast, total dissolved I was not significantly correlated with Cl − (Pearson's r = 0.18, p = 0.273) and was concentrated in porewaters located above the saline lenses with a peak concentration of 4.1 μM beneath the center of the wetland— the highest value for dissolved I ever measured in a terrestrial aquatic system and an order of magnitude above that of seawater. We hypothesize that chromatographic separation between more mobile anions (Cl − , SO 4 2 − , Br − ) and I occurs during droughts when wetland ponds dry and sedimentary iodide (I − ) oxidizes to its less-mobile form, iodate (IO 3 − ). Understanding the origin and geochemical composition of porewater salinity that develops beneath prairie wetlands during drought can help to fingerprint sources of salinity to wetland ponds during wet climate and elucidate halogen systematics in saline and organic-rich subsurface environments associated with hydrocarbon generation.

North Dakota↗

USGS2018

Drought-induced recharge promotes long-term storage of porewater salinity beneath a prairie wetland

Subsurface storage of sulfate salts allows closed-basin wetlands in the semiarid Prairie Pothole Region (PPR) of North America to maintain moderate surface water salinity (total dissolved solids [TDS] from 1 to 10 g L −1 ), which provides critical habitat for communities of aquatic biota. However, it is unclear how the salinity of wetland ponds will respond to a recent shift in mid-continental climate to wetter conditions. To understand better the mechanisms that control surface-subsurface salinity exchanges during regional dry-wet climate cycles, we made a detailed geoelectrical study of a closed-basin prairie wetland (P1 in the Cottonwood Lake Study Area, North Dakota) that is currently experiencing record wet conditions. We found saline lenses of sulfate-rich porewater (TDS > 10 g L −1 ) contained in fine-grained wetland sediments 2–4 m beneath the bathymetric low of the wetland and within the currently ponded area along the shoreline of a prior pond stand ( c . 1983). During the most recent drought (1988–1993), the wetland switched from a groundwater discharge to recharge function, allowing salts dissolved in surface runoff to move into wetland sediments beneath the bathymetric low of the basin. However, groundwater levels during this time did not decline to the elevation of the saline lenses, suggesting these features formed during more extended paleo-droughts and are stable in the subsurface on at least centennial timescales. We hypothesize a “drought-induced recharge” mechanism that allows wetland ponds to maintain moderate salinity under semiarid climate. Discharge of drought-derived saline groundwater has the potential to increase the salinity of wetland ponds during wet climate.

North Dakota↗

USGS2016

Climatic drivers for multidecadal shifts in solute transport and methane production zones within a large peat basin

Northern peatlands are an important source for greenhouse gases, but their capacity to produce methane remains uncertain under changing climatic conditions. We therefore analyzed a 43 year time series of the pore-water chemistry to determine if long-term shifts in precipitation altered the vertical transport of solutes within a large peat basin in northern Minnesota. These data suggest that rates of methane production can be finely tuned to multidecadal shifts in precipitation that drive the vertical penetration of labile carbon substrates within the Glacial Lake Agassiz Peatlands. Tritium and cation profiles demonstrate that only the upper meter of these peat deposits was flushed by downwardly moving recharge from 1965 to 1983 during a Transitional Dry-to-Moist Period. However, a shift to a moister climate after 1984 drove surface waters much deeper, largely flushing the pore waters of all bogs and fens to depths of 2 m. Labile carbon compounds were transported downward from the rhizosphere to the basal peat at this time producing a substantial enrichment of methane in Δ 14 C with respect to the solid-phase peat from 1991 to 2008. These data indicate that labile carbon substrates can fuel deep production zones of methanogenesis that more than doubled in thickness across this large peat basin after 1984. Moreover, the entire peat profile apparently has the capacity to produce methane from labile carbon substrates depending on climate-driven modes of solute transport. Future changes in precipitation may therefore play a central role in determining the source strength of peatlands in the global methane cycle.

Minnesota↗

USGS2009

Improving conceptual models of water and carbon transfer through peat

Northern peatlands store 500 × 10 15 g of organic carbon and are very sensitive to climate change. There is a strong conceptual model of sources, sinks, and pathways of carbon within peatlands, but challenges remain both in understanding the hydrogeology and the linkages between carbon cycling and peat pore water flow. In this chapter, research findings from the glacial Lake Agassiz peatlands are used to develop a conceptual framework for peatland hydrogeology and identify four challenges related to northern peatlands yet to be addressed: (1) develop a better understanding of the extent and net impact of climate-driven groundwater flushing in peatlands; (2) quantify the complexities of heterogeneity on pore water flow and, in particular, reconcile contradictions between peatland hydrogeologic interpretations and isotopic data; (3) understand the hydrogeologic implications of free-phase methane production, entrapment, and release in peatlands; and (4) quantify the impact of arctic and subarctic warming on peatland hydrogeology and its linkage to carbon cycling.

Book chapter↗

USGS2003

Use of hydraulic head to estimate volumetric gas content and ebullition flux in northern peatlands

Hydraulic head was overpressured at middepth in a 4.2‐m thick raised bog in the Glacial Lake Agassiz peatlands of northern Minnesota, and fluctuated in response to atmospheric pressure. Barometric efficiency (BE), determined by calculating ratios of change in hydraulic head to change in atmospheric pressure, ranged from 0.05 to 0.15 during July through November of both 1997 and 1998. The overpressuring and a BE response were caused by free‐phase gas contained primarily in the center of the peat column between two or more semielastic, semiconfining layers of more competent peat. Two methods were used to determine the volume of gas bubbles contained in the peat, one using the degree of overpressuring in the middepth of the peat, and the other relating BE to specific yield of the shallow peat. The volume of gas calculated from the overpressuring method averaged 9%, assuming that the gas was distributed over a 2‐m thick overpressured interval. The volume of gas using the BE method averaged 13%. Temporal changes in overpressuring and in BE indicate that the volume of gaseous‐phase gas also changed with time, most likely because of rapid degassing (ebullition) that allowed sudden loss of gas to the atmosphere. Estimates of gas released during the largest ebullition events ranged from 0.3 to 0.7 mol m −2 d −1 . These ebullition events may contribute a significant source of methane and carbon dioxide to the atmosphere that has so far largely gone unmeasured by gas‐flux chambers or tower‐mounted sensors.

Water Resources Research↗

USGS1982

Preliminary evaluation of the ground-water-flow system in the Twin Cities Metropolitan area, Minnesota

A preliminary quasi-three-dimensional finite-difference ground-water-flow model of the seven-county Twin Cities Metropolitan area was constructed and used to evaluate parameter sensitivity and adequacy of available data. Fourteen geologic units that underlie the study area were grouped into nine hydr,bgeologic units and were incorporated into a five-layer model. The layers in the simulation model include the Mount SimonHinckley, Ironton-Galesville, Prairie du Chien-Jordan, and St. Peter aquifers, and the drift. Sensitivity analyses were made for 19 parameter and boundary-condition specifications. Model results are -most sensitive to recharge and withdrawal rates and to hydrogeologic variations related to drift-filled bedrock valleys. Analyses of available data and results of steady-state simulations indicate that critical data needs for improving the simulation model include spatial and temporal variations in ground-water withdrawals and potentiometric levels, and hydraulic properties of drift filling or partly filling bedrock valleys. Areal distribution of calcium, sodium, sulfate, and chloride concentrations were analyzed to provide information on the hydrologic and geochemical relationships between aquifers. Ground water is generally of the calcium magnesium bicarbonate type. Concentration of dissolved solids in water from the Jordan Sandstone and Mount Simon-Hinckley aquifer generally decreases from southwest to northeast across the study area. This decrease probably reflects differences in the quality of recharge water and geochemical processes within the aquifers, such as ion exchange.

Minnesota↗

USGS1981

Hydrogeologic setting of the Glacial Lake Agassiz Peatlands, northern Minnesota

Seven test holes drilled in the Glacial Lake Agassiz Peatlands indicate that the thickness of surficial materials along a north-south traverse parallel to Minnesota Highway 72 ranges from 163 feet near Blackduck, Minnesota to 57 feet about 3 miles south of Upper Red Lake. Lenses of sand and gravel occur immediately above bedrock on the Itasca moraine and are interbedded with lake clay and till under the peatlands. Vertical head gradients measured in a piezometer nest near Blackduck on the moraine are downward, indicative of recharge to the regional ground-water-flow system. Vertical head gradients are upward in a piezometer nest on a sand beach ridge in the peatlands 12 miles north of Upper Red Lake. Numerical sectional models indicate that this discharge probably comes from local flow systems recharged from ground-water mounds located under large raised bogs.

Minnesota↗

USGS1981

Effect of snowmelt on the quality of Filson Creek and Omaday Lake, northeastern Minnesota

Concentrations of major constituents were determined in the surface water, ground water, and precipitation in Filson Creek watershed to evaluate the effects of acid precipitation on surface-water quality during snowmelt. Concentrations of sulfate increased in Filson Creek and Omaday Lake during snowmelt from less than 2 to 12 milligrams per liter in 1977 and from less than 2 to 4 milligrams per liter in 1979. Hydrogen-ion activity increased from 10 -6.5 to 10 -5.0 during snowmelt in 1977 and from 10 -6.5 to 10 -6.0 in 1979. The magnitude of the increases of sulfate and hydrogen-ion concentrations depend on the (1) timing of the snowmelt, (2) concurrent precipitation, and (3) antecedent soil-moisture conditions. Alkalinity and concentrations of total calcium, magnesium, and sodium in the creek during snowmelt reflect the simple dilution of streamflow with more dilute precipitation. The mixing process is defined by hyperbolic curves of concentration versus discharge and can be modeled by use of a mass-balance equation. Concentrations of silica and total potassium in the creek during snowmelt are less than that at base flow because of dilution and uptake by diatoms and plants, respectively. A quality-assurance study was made to determine the accuracy and precision of the turbidimetric, complexometric (methylthymol blue), and ion-chromatographic methods used to determine concentrations of sulfate in water. Results suggest that the ion-chromatographic method is more accurate and more precise in the detection of sulfate at concentrations of 5 milligrams per liter or less. To obtain accuracy with either the turbidimetric or the complexometric methylthymol blue method, color blanks and turbidity should be determined if concentrations of sulfate are expected to be low, such as in precipitation, or where water is colored by organic material. Interference by color and turbidity is not a factor in the ion-chromatographic method.

Minnesota↗

USGS1980

Hydrologic setting of Williams Lake, Hubbard County, Minnesota

The hydrology and geology of Williams Lake watershed was studied to evaluate the accuracy of various methods used to determine precipitation and evaporation in lake water-balance studies and to define a lake and ground-water system according to approaches suggested by theoretical modeling studies. Regression analysis between estimated and measured precipitation at the lake showed that the accuracy of regionalization techniques is dependent on the closeness of the data network to the lake. For individual storms, the average-value method was found to be better than either the weighted average or isohyetal methods of determining precipitation, but it was least accurate in estimating 14-day average precipitation. The amount of evaporation calculated by the mass-transfer method ranged from 2 to 7 inches per month from July to October 1978, depending on the method used to determine the mass-transfer coefficient. Test drilling indicated that 30 to 150 feet of sand and gravel overlies till in the Williams Lake watershed. A sand lens about 50 feet thick occurs within the till. The configuration of the water table and vertical-head gradients measured from July to December 1978 indicate that ground water moves into the lake from the south and east and moves from the lake into the ground-water reservoir to the west. Preliminary numerical models indicate that the sand lens within the till is effectively isolated from the flow system interacting with the lake and that both inseepage and outseepage were about 1.4 inches from mid-July to mid-October 1978. When estimated as a residual in a water balance, ground water showed a net outseepage only of 1.47 inches.

Minnesota↗

USGS1980

Hydrology and water quality of the copper-nickel study region, northeastern Minnesota

Data were collected on the hydrology of the Copper-Nickel study region to identify the location and nature of groundwater resources, determine the flow characteristics and general quality of the major streams, and determine the potential effects of mining copper and nickel on the hydrologic stream. Groundwater generally occurs in local flow systems within surficial deposits and in fractures in the upper few hundred feet of bedrock. Yields commonly range from 1 to 5 gallons per minute from wells in surficial materials and bedrock, but can be as much as 1,000 gallons per minute from wells in the sand and gravel aquifer underlying the Embarrass River valley. Groundwater generally is calcium-magnesium bicarbonate types. Over a mineralized zone, groundwater has concentrations of copper and nickel greater than 5 micrograms per liter. The average annual runoff from streams in the study area is about 10 inches. About 60% of the annual runoff occurs during snowmelt in spring. Flood peaks are reduced in streams that have surface storage available in on-channel lakes and wetlands. Specific conductance in streams can exceed 250 micromhos per centimeter at 25 Celsius where mine dewatering supplements natural discharge. Estimated groundwater discharge to projected copper-nickel mines ranges from less than 25 to about 2,000 gallons per minute. The introduction of trace metals from future mining activities to the groundwater system can be reduced if tailings basins and stockpiles are located on material which has low permeability, such as till, peat, or bedrock. (USGS)

Minnesota↗

USGS1979

Potential hydrologic effects of peat mining in the Red Lake Peatlands, north-central Minnesota— A project plan

Peat is being considered for fuel in Minnesota. This study will investigate the potential effects of large-scale surface mining of peat on the hydrology and water quality of Upper Red Lake and the Tamarac River. The major aspects of the study are the characterization of the surface-water and groundwater hydrology and water quality, including the trace-metal content of the peat. Data will be collected to construct two- and three-dimensional digital models to simulate the movement of ground water and its relation to surface water in the peatlands, streams, and lakes. After the model is calibrated with field data, it will be used to evaluate the effect of mining peat on the hydrology and water quality of the Upper Red Lake and Tamarac River.

Minnesota↗