Impacts of Urbanization on Base Flow and Recharge Rates, Northeastern Illinois: Summary of Year 1 Activities

During year one of a two-year project to investigate the impacts of urbanization on base flow and ground-water recharge rates in northeastern Illinois, three gaged watersheds in urbanized areas of northeastern Illinois, and one watershed located in rural northwestern Illinois, have been selected for study. The gages have a common period of record extending from October 1952 through the present, a period during which the northeastern Illinois watersheds underwent substantial urbanization. Mean daily discharge data from the gages have been analyzed using an automated hydrograph separation technique, and monthly estimates of mean total discharge, base flow, and direct runoff have been calculated. Spearman rank correlation coefficients indicate a stronger correlation between precipitation and total discharge, base flow, and direct runoff in the northeastern Illinois watersheds than in the rural watershed. Smoothed time-series plots of total discharge, base flow, and direct runoff in the urban watersheds are less consistent with precipitation than similar plots constructed from the rural watershed data. The trends indicate that rates of direct runoff have overtaken rates of base flow in two of the three northeastern Illinois watersheds, but in one of these watersheds, this relationship probably reflects the cessation of effluent discharges to the stream. In general, double-mass curve analysis suggests that, relative to the rural watershed, base flow in the urban watersheds has proportionally decreased, and direct runoff has proportionally increased. The trends suggested by the smoothed time-series plots and the double-mass curves are consistent with a conceptual model of the northeastern Illinois watersheds in which sewering and impervious surfaces have reduced infiltration, and thence ground-water recharge and base flow, in the watersheds.Ope

The value of near infrared reflectance measurement of feedgrain nutrient composition

To determine the value of near infrared reflectance (NIR) measurement of corn nutrient composition to livestock feeders, sequential decision models of beef cattle and swine feeding were developed. Corn composition data from the National Feedstuff Composition Data Bank (NFCDB) were used to derive probability density functions for crude protein, fat, and lysine content. Expected values of profit and other variables were computed by numerical integration. Means of crude protein and lysine of the NFCDB sample were lower and higher, respectively, than National Research Council estimates. These differences caused errors in diet formulations which resulted in losses due to imperfect information of up to 47 per year per head of one-time capacity in feeding yearling steers, up to 41 per year per head of one-time capacity in feeding steer calves and up to 6.50 per year per head of one-time capacity in feeding swine;The difference between the expected values of NIR-generated information and of NFCDB sample means was very small. One-time capacities of approximately 40,000 yearling cattle, 12,500 calves of 2,200 swine were necessary to justify investment in an analyzer based on net present value when NIR-generated information (versus NFCDB sample means) was used to formulate diets to meet recommended nutrient allowances. Minimum one-time capacities declined to 2,550 yearling cattle, 1,700 calves or 1,080 swine when diets were formulated to meet nutrient requirements;NIR-generated information was more valuable to yearling steer feeders than to steer calf feeders on an annual basis, given continuous production. This result was due to yearling steers\u27 requiring fewer days to reach market weight thereby allowing more animals to be fed per year;Losses due to imperfect knowledge in beef cattle feeding were largest when corn had low crude protein content and high fat content. Losses incurred by swine feeders were highest when crude protein content was high and fat content was low;The use of NIR results to reject corn with low crude protein and/or fat content increased the expected value of NIR-generated information by roughly ten percent for both species. This gain in expected value does now, however, account for costs that may be incurred by feeders in finding corn that meets their specified standards