Geology topics

Research about Great Plains

Source-linked reports with geographic coverage including Great Plains.

42 records · Page 3Linked to original sources

USGS1998

Downstream effects of dams on channel geometry and bottomland vegetation: Regional patterns in the Great Plains

The response of rivers and riparian forests to upstream dams shows a regional pattern related to physiographic and climatic factors that influence channel geometry. We carried out a spatial analysis of the response of channel geometry to 35 dams in the Great Plains and Central Lowlands, USA. The principal response of a braided channel to an upstream dam is channel-narrowing, and the principal response of a meandering channel is a reduction in channel migration rate. Prior to water management, braided channels were most common in the southwestern Plains where sand is abundant, whereas meandering channels were most common in the northern and eastern Plains. The dominant response to upstream dams has been channel-narrowing in the southwestern Plains (e.g., six of nine cases in the High Plains) and reduction in migration rate in the north and east (e.g., all of twelve cases in the Missouri Plateau and Western Lake Regions). Channel-narrowing is associated with a burst of establishment of native and exotic woody riparian pioneer species on the former channel bed. In contrast, reduction in channel migration rate is associated with a decrease in reproduction of woody riparian pioneers. Thus, riparian pioneer forests along large rivers in the southwestern Plains have temporarily increased following dam construction while such forests in the north and east have decreased. These patterns explain apparent contradictions in conclusions of studies that focused on single rivers or small regions and provide a framework for predicting effects of dams on large rivers in the Great Plains and elsewhere. These conclusions are valid only for large rivers. A spatial analysis of channel width along 286 streams ranging in mean annual discharge from 0.004 to 1370 cubic meters per second did not produce the same clear regional pattern, in part because the channel geometries of small and large streams are affected differently by a sandy watershed.

Great Plains↗

USGS1997

NDVI, C3 and C4 production, and distributions in Great Plains grassland land cover classes

The distributions of C 3 and C 4 grasses were used to interpret the distribution, seasonal performance, and potential production of grasslands in the Great Plains of North America. Thirteen major grassland seasonal land cover classes were studied with data from three distinct sources. Normalized Difference Vegetation Index (NDVI) data derived from the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) sensor were collected for each pixel over a 5-yr period (1989–1993), analyzed for quantitative attributes and seasonal relationships, and then aggregated by land cover class. Data from the State Soil Geographic (STATSGO) database were used to identify dominant plant species contributing to the potential production in each map unit. These species were identified as C 3 or C 4 , and contributions to production were aggregated to provide estimates of the percentage of C 3 and C 4 production for each intersection of the STATSGO map units and the seasonal land cover classes. Carbon isotope values were obtained at specific sites from the soil organic matter of the upper horizon of soil cores and were related to STATSGO estimates of potential production. The grassland classes were distributed with broad northwest-to-southeast orientations. Some classes had large variations in C 3 and C 4 composition with high proportions of C 4 species in the south and low proportions in the north. This diversity of photosynthetic types within land cover classes that cross regions of different temperature and precipitation results in similar seasonal patterns and magnitudes of NDVI. The easternmost class, 65, containing tallgrass prairie components, bluestem, Indiangrass, and switchgrass, possessed the highest maximum NDVI and time-integrated NDVI values each year. Grassland classes varied over 5 yr from a high integrated NDVI mean of 4.9 in class 65 in the east to a low of 1.2 in class 76 (sand sage, blue grama, wheatgrass, and buffalograss) in the southwest. Although environmental conditions varied widely during the 5 yr, the rankings of class performance were consistent across years for these NDVI metrics. Land cover classes were less consistent in time of onset, which was often earlier in areas in the north dominated by C 3 grasses than in areas to the south dominated by C 4 grasses. At the level of seasonal land cover classes, no significant relationship was found between the proportions of C 3 and C 4 species and estimates of potential production derived from the STATSGO database or inferred from the seasonal patterns of NDVI. The isotopic data from specific sites and the potential production data from STATSGO suggest similar patterns of high proportional production by C 4 species throughout the south and a decline in proportional production north of the central Great Plains. The land cover classes integrate ecosystem units that encompass a wide diversity of species and C 3 and C 4 proportions and provide a classification that consistently captures significant ecosystem parameters for the Great Plains.

Colorado, Kansas, Montana, Nebraska, New Mexico, N↗

USGS1995

Conservation Reserve Program and migratory birds in the northern Great Plains

U.S. Department of Agriculture programs have mediated supply and demand of commodities and maintained the agricultural industry, but several programs have also offered various kinds of conservation benefits. The 1985 Food Security Act (Farm Bill) featured the Conservation Reserve Program (CRP), which paid farmers to plant perennial cover on highly erodible lands and to leave this land intact for a 10-year contract period. During that period we conducted two studies to determine the value of CRP fields to breeding birds in the northern Great Plains.

Great Plains↗

USGS1993

The potential response of eolian sands to greenhouse warming and precipitation reduction on the Great Plains of the U.S.A.

Sand dunes and sand sheets are extensive on the semi-arid GreatPlains but are at present stabilized by a sparse vegetation cover. Use of a dune mobility index, which incorporates wind strength and the ratio of mean annual precipitation to potential evapotranspiration, shows that under predicted greenhouse climate effects of increased temperature and reduced precipitation, sand dunes and sand sheets on the GreatPlains are likely to become reactivated over a significant part of the region.

Great Plains↗

USGS1975

The determination, assessment, and design of "in-stream value" studies for the northern Great Plains region

An extensive literature review was conducted to determine the discharge requirements of various components of a warm water fishery. Where exact hydrologic parameters were not measured directly in individual studies, they were estimated from inferred statements and knowledge of hydrologic variables leading to certain instream conditions. From this information it was possible to determine which components of the stream community would be most seriously affected by reduced discharges. In addition, a number of different methods used in the recommendation of minimum streamflows was reviewed. These methods were evaluated for their reliability and ease of use. It was concluded that a method for recommending minimum discharges should not sacrifice reliability for expediency. A methodology is proposed for the recommendation of minimum discharges for a warm water fishery. This method utilizes field measurements of critical stream areas and biological criteria determined from the used of indicator species. For large rivers, migration and spawning requirements are analyzed using the paddlefish ( Polyodon spathula ) as the indicator species. For smaller rivers, the suggested indicator species is the sauger ( Stizostedion canadense ). Rearing flows are determined on the basis of stream productivity by analyzing macroinvertebrate habits, and on the basis of fish habitat typing. The indicator species for determining adequate fish habitat is the stonecat ( Notorus flavus ). A number of variables were identified which might require a greater amount of in-stream flow than the fishery, per se. These variables included streamflow needs for riparian and other sub-irrigated vegetation, water quality parameters, anchor ice formation, and the relationship between discharge and sediment yield. Information concerning these variables is insufficient at this time to determine whether a variable will "over-ride" the streamflow requirement for the fishery itself. Further research is needed in these areas, and several investigative methods for conducting such research are proposed.

Great Plains↗

USGS1905

Preliminary report on the geology and underground water resources of the central Great Plains

The area to which this report relates is shown in Pl. II. It comprises the greater portions of South Dakota, Nebraska, and Kansas, and the eastern portions of Colorado and of Wyoming, an area of about one-half million square miles. It is the result of my investigations during the past eight years, but includes also all available data from many sources. I have been aided by various field assistants, those deserving special mention being Messrs. C. A. Fisher, C. C. O'Harra, J.E. Todd, the late C. M. Hall, G. B. Eichardson, W. S. Tangier Smith, E. H. Barbour, and the late J. E. Macfarland. On account of its size, the region presents relatively diverse geologic conditions, but comprises comparatively few formations, most of which are widespread. The question of water supply, both overground and underground, is one of great interest to the people in this district, and although considerable progress has been made in some sections in developing well waters, there are vast areas in which the present supplies are inadequate, even for local domestic use. In order to understand the relations of the underground waters it has been necessary to investigate the geology, especially the structure and stratigraphy of the water-bearing and associated formations. This part of the work has required a very large amount of special field study, and the present results show that extended investigation will be required before many important questions of geology can be fully understood.

Colorado, Kansas, Nebraska, South Dakota, Wyoming↗