Document Type

Dissertation - Open Access

Award Date

1973

Degree Name

Doctor of Philosophy (PhD)

Department

Civil Engineering

First Advisor

James N. Dornbush

Abstract

Surface runoff from snowmelt and rainfall was measured 1n eastern South Dakota from seven sites (7.18 to 18.69 acres) during 1971 and 1972. All sites had single crops which included corn, oats, pasture and hayland. All land was farmed under normal farming conditions. Samples were taken periodically throughout each runoff event, and a single composite sample was made from the individual samples for a particular site. The composite sample represented the entire runoff event. The amount of rainfall and the runoff flow were measured. Determinations on the composite sample included total coliform, fecal coliform, fecal streptococcus, soluble pesticides, specific conductance, raw and soluble chemical oxygen demand, raw and soluble total kjeldahl nitrogen, raw and soluble total phosphorus, suspended solids, total residue and nitrates. In addition, ammonia-nitrogen was determined for some samples; and when possible, pesticide determinations were made on mud samples. Runoff samples from 91 snowmelt events and 32 rainfall events were collected over the two year period. The first year represented a season of below normal precipitation and the second year was a year of above average precipitation. Sediment losses were considerably below losses predicted by the "universal" soil-loss equation. This was attributed to differences in runoff plot size and local hydrologic conditions. Most of the sediment lost was from the cultivated fields and only small amounts washed off fields in permanent grass. Host of the soil-loss happened. during short duration, highly intense summer rainstorms. Coliform and fecal coliform levels were consistently greater than accepted surface water quality criteria. The fecal coliform to fecal streptococcus ratio appears to indicate contamination from a nonhuman source, as expected. Pesticide concentrations were low in both water and sediment samples. Analyses generally showed levels below the analytical test limits. Nutrient losses ranged from 0.03 to 3.0 lb/acre/yr of nitrogen and from 0.01 to 0.72 lb/acre/yr of phosphorus. Considerable amounts of nutrients were found to be soluble and/or associated with snowmelt runoff.

Library of Congress Subject Headings

Runoff
Water -- Pollution -- South Dakota -- Brookings County

Format

application/pdf

Publisher

South Dakota State University

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