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C.J. Londquist

Publications and source records attributed to C.J. Londquist.

17 recordsLinked to original sources
USGS1990

Documentation of model input and output values for the geohydrology and mathematical simulation of the Pajaro Valley aquifer system, Santa Cruz and Monterey counties, California

This report contains listings of the model input and sample output for simulation of the Pajaro Valley aquifer system, Santa Cruz and Monterey Counties, California. The files are contained on a 5 1/4-inch diskette. The decompressed files require approximately 5.3 megabytes of disk space on an IBM-compatible microcomputer. (USGS)

Open-File Report↗
USGS1988

Geohydrology and mathematical simulation of the Pajaro Valley aquifer system, Santa Cruz and Monterey Counties, California

Groundwater development has resulted in lowered water levels and seawater intrusion in the Pajaro Valley, California. An investigation was undertaken to describe the geohydrology of the groundwater flow system and to evaluate the response of the system to pumping stresses by using a mathematical model. The aquifer system consists of three aquifers. The lower aquifer is in fluvial sequences of Quaternary Aromas Sand below interbedded clay layers. The middle aquifer is in upper fluvial and lower eolian sequence of Aromas Sand, and in overlying basal gravels in terrace deposits and alluvium. Weathered soil zones in the Aromas Sand, and clay layers in the terrace deposits and alluvium overlie the middle aquifer. The upper aquifer is actually many discontinuous water bearing zones in the Aromas Sand, terrace deposits, alluvium, and dune sand. The three aquifers are represented in the mathematical model by three model layers separated by two confining layers. Model-generated water budgets for the 11-year simulation period show that storage decreased by 23,000 acre-ft, mostly during the 1976-77 drought. The calibrated model can simulate, with acceptable accuracy, both semiannual and long-term trends of potentiometric heads in parts of the lower and middle layers. (USGS)

California↗
USGS1978

Water-resources appraisal of the Wet Mountain Valley, in parts of Custer and Fremont counties, Colorado

The Wet Mountain Valley is an intermontane trough filled to a depth of at least 6,700 feet with unconsolidated deposits. Ground water occurs under both artesian and water-table conditions within the basin-fill aquifer and ground-water moverment is toward Grape and Texas Creeks. The depth to the water table is less than 10 feet in an area of about 40 square miles along the central part of the valley and is less than 100 feet in most of the remainder of the valley. Ground water stored in the upper 200 feet of saturated basin-fill sediments is estimated to total 1.5 million acre-feet. Yields greater than 50 gallons per minute generally can be expected from wells in the central part of the basin-fill aquifer, and yields less than 50 gallons per minute are generally reported from wells around the edge of the basin-fill aquifer. Yields of wells in the mountainous areas are generally less than 20 gallons per minute. Most streamflow occurs as a result of snowmelt runoff during June and July. The long-term annual runoff at seven stations ranges from an estimated 0.02 cubic foot per second per square mile to an estimated 1.17 cubic feet per second per square mile, generaly increasing with station altitude. Generalized annyal water budgets for two areas in the Wet Mountain Valley indicate that surface-water outflow is only 7 to 11 percent of the total water supply from precipitation and other sources. The remaining water is lost to the atmosphere by evapotranspiration. The quality of both the surface and ground water is generally within the recommended limits for drinking water set by the U.S. Public Health Service. (Woodard-USGS)

Water-Resources Investigations Report↗