Conference Papers

The one-dimensional consolidation theory equation is solved for an aquifer system using a pseudospectral method. The spatial derivatives are computed using Fast Fourier Transforms and the time derivative is solved using a fourth-order Runge-Kutta scheme. The computer model calculates compaction based on the void ratio changes accumulated during the simulated periods of time. Compactions...

Certain themes arise repeatedly in current literature dealing with the physical hydrology of the interface between the atmosphere and the continents. Papers contributed to the 1991 International Association of Hydrological Sciences Symposium on Hydrological Interactions between Atmosphere, Soil and Vegetation echo these themes, which are discussed in this paper. The land-atmosphere...

A budget of atrazine and desethylatrazine loads was computed for a 116-kilometer reach of the Cedar River in Iowa to determine where these compounds enter the river during base-flow conditions. Loads were determined by measuring discharge and concentrations of the compounds for four main-stem sites along the Cedar River and for 27 tributaries on September 20-22, 1989. Tributaries...

The ongoing efforts to create a more accessible and user friendly Spatial Data Transfer Standard include the development of a Profile for Vector Data and the development of a library of public domain software tools to support the encoding and decoding process. A profile is, in effect, a limited subset of the standard. The best way to use the standard is to first define a profile...

Strontium isotope studies of carbonates from soils, veins, eolian dust and Paleozoic basement sampled near Crater Flat, southwest of Yucca Mountain, provide evidence for the origins of these materials. Vein and soil carbonates have nearly identical ranges of 87Sr/86Sr, and eolian material has 87Sr/86Sr ratios at the lower end of the pedogenic range. The average 87Sr/86Sr of Paleozoic...

Half of Illinois' 38 million acres were planted in corn and soybeans in 1988. On the 19 million acres planted in corn and soybeans, approximately 1 million tons of nitrogen fertilizer and 50 million pounds of pesticides were applied. Because groundwater is the water supply for over 90 percent of rural Illinois, the occurrence of agricultural chemicals in groundwater in Illinois is of...