Water Follows the People: Analysis of Water Use in the Western Great Plains and Rocky Mountains of Colorado, USA

The highest hail-thunderstorm ratio in the country is found over the western Great Plains and the east slope of the Rocky Mountains in a band extending from the Rio Grande northward to the Canadian border. Point frequency of hail over western United States is of little value in determining relative area exposures to hail. Frequency of hail in a metropolitan area such as Denver is at least ten times as great as random point frequency within that area. Hail probably occurs aloft during the growing stage of each thunderstorm which forms in the Denver Section. Hail is predominantly a post-coldfrontal phenomenon at Denver, but no satisfactory method has been found so far of predicting damaging hail. Airborne radar storm detection equipment offers the greatest hope of avoiding damaging hail in flight.

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THE MIDDLE PLEISTOCENE UNCONFORMITY AND MIS 12-11 (~478-385 KA): GLACIOFLUVIAL PROCESSES OVERRIDE LATE MIOCENE-MIDDLE PLEISTOCENE (~6 MA-500 KA) TECTONO-MAGMATIC CAPTURE AND DEEP-CANYON INCISION, WESTERN GREAT PLAINS-SOUTHERN ROCKY MOUNTAINS-COLORADO PLATEAU REGION, NORTH AMERICA

10.1130/abs/2019am-339129 ◽

2019 ◽

Author(s):

Cal Ruleman ◽

◽

Adam M. Hudson ◽

Marc W. Caffee ◽

Keith A. Brugger

Keyword(s):

North America ◽

Great Plains ◽

Late Miocene ◽

Rocky Mountains ◽

Colorado Plateau ◽

Middle Pleistocene ◽

Plateau Region ◽

Southern Rocky Mountains ◽

Western Great Plains

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Drought and vegetation change in the central Rocky Mountains and western Great Plains: potential climatic mechanisms associated with megadrought conditions at 4200 cal yr BP

Climate of the Past ◽

10.5194/cp-14-1195-2018 ◽

2018 ◽

Vol 14 (8) ◽

pp. 1195-1212 ◽

Cited By ~ 6

Author(s):

Vachel A. Carter ◽

Jacqueline J. Shinker ◽

Jonathon Preece

Keyword(s):

Great Plains ◽

Rocky Mountains ◽

Vegetation Change ◽

Specific Humidity ◽

Northern Great Plains ◽

Study Region ◽

Normal Heights ◽

Regional Drought ◽

Central Rocky Mountains ◽

Western Great Plains

Abstract. Droughts are a naturally re-occurring phenomena that result in economic and societal losses. Yet, the most historic droughts that occurred in the 1930s and 1950s in the Great Plains and western United States were both shorter in duration and less severe than megadroughts that have plagued the region in the past. Roughly 4200 years ago, a ∼150-year long megadrought occurred in the central Rocky Mountains, as indicated by sedimentary pollen evidence documenting a brief and unique change in vegetation composition from Long Lake, southeastern Wyoming. Neighbouring the central Rocky Mountains, several dune fields reactivated in the western Great Plains around this time period illustrating a severe regional drought. While sedimentary pollen provides evidence of past drought, paleoecological evidence does not provide context for the climate mechanisms that may have caused the drought. Thus, a modern climate analogue technique was applied to the sedimentary pollen and regional dune reactivation evidence identified from the region to provide a conceptual framework for exploring possible mechanisms responsible for the observed ecological changes. The modern climate analogues of 2002/2012 illustrate that warm and dry conditions persisted through the growing season and were associated with anomalously higher-than-normal geopotential heights centred over the Great Plains. In the spring, higher-than-normal heights suppressed moisture transport via the low-level jet from the Gulf of Mexico creating a more southwesterly component of flow. In the summer, higher-than-normal heights persisted over the northern Great Plains resulting in a wind shift with an easterly component of flow, drawing in dry continental air into the study region. In both cases, lower-than-normal moisture in the atmosphere (via 850 mbar specific humidity) inhibited uplift and potential precipitation. Thus, if the present scenario existed during the 4.2 ka drought, the associated climatic responses are consistent with local and regional proxy data suggesting regional drought conditions in the central Rocky Mountains and western Great Plains.

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Postdepositional tilt of the Miocene-Pliocene Ogallala Group on the western Great Plains: Evidence of late Cenozoic uplift of the Rocky Mountains

Geology ◽

10.1130/0091-7613(2002)030<0063:ptotmp>2.0.co;2 ◽

2002 ◽

Vol 30 (1) ◽

pp. 63 ◽

Cited By ~ 63

Author(s):

Margaret E. McMillan ◽

Charles L. Angevine ◽

Paul L. Heller

Keyword(s):

Great Plains ◽

Rocky Mountains ◽

Late Cenozoic ◽

Western Great Plains

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Expression of the “4.2 ka event” drought in the southern Rocky Mountains, USA

10.5194/cp-2021-149 ◽

2021 ◽

Author(s):

David Thomas Liefert ◽

Bryan Nolan Shuman

Keyword(s):

Great Plains ◽

North American ◽

Rocky Mountains ◽

Winter Precipitation ◽

Mountain Lake ◽

Pollen Record ◽

Southern Rocky Mountains ◽

The North ◽

Climate Event ◽

Western Great Plains

Abstract. The use of the climatic anomaly known as the “4.2 ka event” as the stratigraphic division between the mid- and late Holocene has prompted debate over its impact, geographic pattern, and significance. The anomaly has primarily been described as abrupt drying, but evidence of hydroclimate change at ca. 4 ka is inconsistent among sites globally, and few sites in North America document a major drought. Climate records from the southern Rocky Mountains demonstrate the challenge with diagnosing the extent and severity of the anomaly. Dune-field chronologies and a pollen record in southeast Wyoming reveal several centuries of low moisture at around 4.2 ka and prominent low stands in lakes in Colorado suggest the drought was unique amid Holocene variability, but detailed carbonate oxygen isotope (δ18Ocarb) records from Colorado do not record it. We find new evidence from δ18Ocarb in a small mountain lake in southeast Wyoming of an abrupt reduction in effective moisture or snowpack from approximately 4.2–4 ka that coincides in time with the other evidence from the southern Rocky Mountains and the western Great Plains of regional drying at around 4.2 ka. We find that the δ18Ocarb in our record may reflect cool-season inputs into the lake, which do not appear to track the strong enrichment of heavy oxygen by evaporation during summer months today. The modern relationship differs from some widely applied conceptual models of lake-isotope systems and may indicate reduced winter precipitation rather than enhanced evaporation at ca. 4.2 ka. Inconsistencies among the North American records, particularly in δ18Ocarb trends, thus show that site-specific factors can prevent identification of the patterns of multi-century drought. However, the prominence of the drought at ca. 4 ka among a growing number of sites in the North American interior suggests it was a regionally substantial climate event amid other Holocene variability.

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DUST IN THE WIND: INFLUENCES ON THE PRESERVATION OF VOLCANICLASTICS WITHIN THE EOCENE-OLIGOCENE WHITE RIVER SEQUENCE OF THE GREAT PLAINS AND MIDDLE ROCKY MOUNTAINS

10.1130/abs/2016am-287515 ◽

2016 ◽

Author(s):

Dennis O. Terry ◽

◽

Emmett Evanoff

Keyword(s):

Great Plains ◽

Rocky Mountains ◽

White River

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Diverse Management Strategies Produce Similar Ecological Outcomes on Ranches in Western Great Plains: Social-Ecological Assessment

Rangeland Ecology & Management ◽

10.1016/j.rama.2017.08.001 ◽

2018 ◽

Vol 71 (5) ◽

pp. 626-636 ◽

Cited By ~ 18

Author(s):

Hailey Wilmer ◽

David J. Augustine ◽

Justin D. Derner ◽

María E. Fernández-Giménez ◽

David D. Briske ◽

...

Keyword(s):

Great Plains ◽

Management Strategies ◽

Ecological Assessment ◽

Social Ecological ◽

Western Great Plains

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Distribution of Gaseous 12CO2, 13CO2, and 14CO2 in the Sub-Soil Unsaturated Zone of the Western US Great Plains

Radiocarbon ◽

10.1017/s0033822200005622 ◽

1983 ◽

Vol 25 (2) ◽

pp. 315-346 ◽

Cited By ~ 49

Author(s):

D C Thorstenson ◽

E P Weeks ◽

Herbert Haas ◽

D W Fisher

Keyword(s):

Great Plains ◽

Land Surface ◽

Unsaturated Zone ◽

Diffusion Theory ◽

The United States ◽

Atmospheric Gases ◽

Sources And Sinks ◽

Western Us ◽

Partial Pressures ◽

Western Great Plains

Data on the depth distribution of the major atmospheric gases and the abundance of gaseous 12CO2, 13CO2, and 14CO2 in the subsoil unsaturated zone have been obtained from several sites in the western Great Plains of the United States. Sample profiles range from land surface to depths of 50m. Although each site must be considered on an individual basis, several general statements can be made regarding the profiles. 1) Diffusion of these gaseous molecules through the unsaturated zone is an important transport mechanism. 2) As predicted by diffusion theory, depth profiles of the various isotopic species of CO2 differ substantially from one another, depending on individual sources and sinks such as root respiration and oxidation of organic carbon at depth. 3) In general, post-bomb (> 100% modern) 14C activities are not observed in the deep unsaturated zone, in contrast to diffusion model predictions. 4) In spite of generally decreasing 14C activities with depth, absolute partial pressures of 14CO2 in the subsoil unsaturated zone are 1–2 orders of magnitude higher than the partial pressure of 14CO2 in the atmosphere.

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