Physical History of the Platte River in Nebraska

Home Browse Search

three or four miles, then left her on a bar and abandoned entirely all further attempts to navigate this river * * *. In concluding their discussion of extremely low flows experienced on the Platte River, Eschner et al. (1983) state the following, If the river did not go dry every summer, the flow became relatively insignificant, a "mere trickle of water among sandy shoals (Ghent, 1929 p. 128). " Between the junction of the North Platte and South Platte Rivers and the Loup river, the Platte may have gone dry during years of low precipitation and probably was reduced to a trickle in other years. The information presented above indicates, as concluded by Eschner et al. (1983), that indeed flow on the Platte River during the summer after the spring peak was typically very low and, at least on some occasions, went dry over extended lengths of the river. They characterize the Platte River regarding flow as follows, "Above the confluence with the Loup, the Platte was an intermittent river. It carried little water during the late summer and dried up completely in some years. " 2.3 Groundwater History A description of the sedimentary deposits underlying the Platte River was provided by Eschner et al. (1983). They stated the following: Unconsolidated deposits of the Platte River valley in the study area consist of Quaternary sediments, which include Holocene alluvium. The Ogallala formation of Tertiary age and Pierre Shale and Niobrara Formation of Cretaceous age underlie the Quaternary sediments in the Platte River Valley . .. Quaternary sediments and, where present, the Ogallala Formation, are the principal aquifers in the Platte River Valley. .. Thickness of saturated alluvium varies from about 6 in to more than 122 m because of an irregular bedrock surface (Bentall, 1975a). Thus, there is an aquifer of significant proportion that stores groundwater beneath the valley floor of the Platte River. This significant volume of water has been the source for the large numbers of wells that have been developed as previously discussed (see Section 2.1.4). Groundwater levels along the Platte River are an area of concern with respect to habitat due to the concept that wetlands affected by groundwater may be a significant source of both habitat and food for wildlife. Groundwater in the vicinity of the Platte River has been shown to be closely tied to the water surface elevation in the river itself as demonstrated by the hydraulic linkage between the river and groundwater levels documented in Eschner et al. (1983). This report states, "A study near Grand Island indicates that ground -water levels within 0.8 km of the river in that area respond within 24 hours to changes in river stage (Hurr, 1981)." 18