Geology topics

Leonard F. Konikow

Publications and source records attributed to Leonard F. Konikow.

79 records · Page 5Linked to original sources

USGS1981

Role of solute-transport models in the analysis of groundwater salinity problems in agricultural areas

Undesirable salinity increases occur in both groundwater and surface water and are commonly related to agricultural practices. Groundwater recharge from precipitation or irrigation will transport and disperse residual salts concentrated by evapotranspiration, salts leached from soil and aquifer materials, as well as some dissolved fertilizers and pesticides. Where stream salinity is affected by agricultural practices, the increases in salt load usually are attributable mostly to a groundwater component of flow. Thus, efforts to predict, manage, or control stream salinity increases should consider the role of groundwater in salt transport. Two examples of groundwater salinity problems in Colorado, U.S.A., illustrate that a model which simulates accurately the transport and dispersion of solutes in flowing groundwater can be (1) a valuable investigative tool to help understand the processes and parameters controlling the movement and fate of the salt, and (2) a valuable management tool for predicting responses and optimizing the development and use of the total water resource.

Colorado↗

USGS1979

Hexavalent chromium in the ground and surface waters near Telluride, Colorado; preliminary data report

Data showing results of 38 groundwater and 25 surface-water samples analyzed for hexavalent chromium are presented. Most samples were taken within the Telluride, Colo., city limits during October 1978. Twenty-four of the 38 groundwater samples (63%) contained more than 50 micrograms per liter of hexavalent chromium. Excluding the mill tailings pond 6 of the 23 surface-water samples (26%) contained more than 50 micrograms per liter of hexavalent chromium. Hexavalent chromium concentrations in groundwaters ranged from 0 to 2700 micrograms per liter and in surface waters from 0 to 160 micrograms per liter.

Colorado↗

USGS1978

Hydrogeologic considerations for an interstate ground-water compact on the Madison aquifer, northern Great Plains

The development of an interstate ground-water compact for the Madison aquifer in the Northern Great Plains may provide a framework to allocate equitably this large ground-water resource while avoiding possible future interstate legal conflicts. However, some technical problems will have to be resolved first. A compact designed to regulate or to allocate the available ground water will have to be written in very precise, legally acceptable definitions. The required definitions may infer a degree of measurement accuracy that cannot be technically or economically provided. Therefore, a trade off may be required between preserving natural conditions and allowing beneficial use of the ground-water resource.

Montana;North Dakota;South Dakota;Wyoming↗

USGS1978

Evaluation of hydrogeologic aspects of proposed salinity control in Paradox Valley, Colorado

The salt load in the Dolores River increases by about 200,000 tons per year where it crosses Paradox Valley, Colorado, because of the discharge of a sodium chloride brine from an underlying aquifer. A ground-water management program to nearly eliminate this major source of salt, which eventually enters the Colorado River, can be designed on the basis of an accurate description of the hydrogeologic framework of Paradox Valley.

Colorado↗

USGS1977

Derivation of equations describing solute transport in ground water

A general equation describing the three-dimensional transport and dispersion of a reacting solute in flowing ground water is derived from the principle of conservation of mass. The derivation presented is more detailed but less rigorous than derivations published previously. The general solute-transport equation relates concentration changes to hydrodynamic dispersion, convective transport, fluid sources and sinks, and chemical reactions. Because both dispersion and convective transport depend on the velocity of ground-water flow, the solute-transport equation must be solved in conjunction with the ground-water flow equation. (Woodard-USGS)

Water-Resources Investigations Report↗

USGS1977

Modeling chloride movement in the alluvial aquifer at the Rocky Mountain Arsenal, Colorado

A solute-transport model that can be used to predict the movement of dissolved chemicals in flowing ground water was applied to a problem of ground-water contamination at the Rocky Mountain Arsenal, near Denver, Colo. The model couples a finite-difference solution to the ground-water flow equation with the method-of-characteristics solution to the solute-transport equation. From 1943 to 1956 liquid industrial wastes containing high chloride concentrations were disposed into unlined ponds at the Arsenal. Wastes seeped out of the unlined disposal ponds and spread for many square miles in the underlying shallow alluvial aquifer. Since 1956 disposal has been into an asphalt-lined reservoir, which contributed to a decline in ground-water contamination by 1972. The simulation model quantitatively integrated the effects of the major factors that controlled changes in chloride concentrations and accurately reproduced the 30-year history of chloride ground-water contamination. Analysis of the simulation results indicates that the geologic framework of the area markedly restricted the transport and dispersion of dissolved chemicals in the alluvium. Dilution, from irrigation recharge and seepage from unlined canals, was an important factor in reducing the level of chloride concentrations downgradient from the Arsenal. Similarly, recharge of uncontaminated water from the unlined ponds since 1956 has helped to dilute and flush the contaminated ground water.

Colorado↗

USGS1976

Preliminary digital model of ground-water flow in the Madison Group, Powder River Basin and adjacent areas, Wyoming, Montana, South Dakota, North Dakota, and Nebraska

A digital simulation model was used to analyze regional ground-water flow in the Madison Group aquifer in the Powder River Basin in Montana and Wyoming and adjacent areas. Most recharge to the aquifer originates in or near the outcrop areas of the Madison in the Bighorn Mountains and Black Hills, and most discharge occurs through springs and wells. Flow through the aquifer in the modeled areas was approximately 200 cubic feet per second. The aquifer can probably sustain increased ground-water withdrawals of up to several tens of cubic feet per second, but these withdrawals probably would significantly lower the potentiometric surface in the Madison aquifer in a large part of the basin. (Woodard-USGS)

Water-Resources Investigations Report↗