The authors demonstrate the importance of the simulation of the water quantity exchange between river water and groundwater to a better understanding of the hydrologic relations between a river and nearby aquifer wher...The authors demonstrate the importance of the simulation of the water quantity exchange between river water and groundwater to a better understanding of the hydrologic relations between a river and nearby aquifer where groundwater is pumped extensively but only seasonally. And MODFLOW is used to design the stream aquifer model in which the pumpage of more than 1000 wells was simulated. The river gaining and river losing processes were analyzed. Simulation results suggest that continuation of over extraction of groundwater will gradually increase the depletion volume in the river year after year and more depletion will occur in later years. The exchange manner between groundwater and the Platte River differs from place to place. The Platte River loses water to the adjacent aquifer in the west part of the study area, and gains water from the adjacent aquifer in the east part of the study area.展开更多
In the fall of 2018, Kansas City—the hometown of Edgar Snow,a noted American journalist known throughout China for his strong relationship with the country—held a grand conference to mark the80th anniversary of the ...In the fall of 2018, Kansas City—the hometown of Edgar Snow,a noted American journalist known throughout China for his strong relationship with the country—held a grand conference to mark the80th anniversary of the publication of Snow’s classic book Red Star Over China. More than 50 experts and scholars from the United States and China gathered on Oct 4 to 6 to remember this old friend of the Chinese people and discuss topics such as USChina relations.展开更多
Detailed topographic maps show multiple stream valleys and what are probably dismembered stream valleys that extend completely across Wyoming’s northern Laramie Mountains. Several of the most obvious valleys are desc...Detailed topographic maps show multiple stream valleys and what are probably dismembered stream valleys that extend completely across Wyoming’s northern Laramie Mountains. Several of the most obvious valleys are described with valley origins first explained (or attempted to be explained) from the commonly accepted regional geomorphology paradigm (accepted paradigm) perspective and second from a recently proposed regional geomorphology paradigm (new paradigm) perspective in an effort to determine which of the two paradigms provides the simplest explanations. Accepted paradigm explanations require at least some of the valley erosion to have occurred prior to deposition of Oligocene and Miocene sediments that once covered the northern Laramie Mountains (with some of the exhumed valleys now containing sediment cover remnants). In contrast the fundamentally different new paradigm requires immense south-oriented continental ice sheet melt water floods to have crossed the region as ice sheet related crustal warping raised the region and the Laramie Mountains (and implies sediments now partially filling some of the valleys are probably flood deposited materials). The new paradigm provides simpler explanations for the origins of the valleys now extending completely across the northern Laramie Mountains and also for their related barbed tributaries, truncated side valleys, and drainage route U-turns than the accepted paradigm, although the new paradigm also leads to a fundamentally different middle and late Cenozoic regional geologic history than is currently recognized. One paradigm cannot be used to judge a different paradigm, but the paradigms can be compared based on their ability to explain evidence and Occam’s Razor can determine which of the two paradigms provides the simplest explanations. New paradigm explanations for northern Laramie Mountains valley origins investigated here require fewer assumptions than the accepted paradigm explanations suggesting the new paradigm merits serious future consideration.展开更多
Drainage divides along a southern Laramie Range crest area and in the nearby southeast Wyoming Gangplank area (as observed on detailed topographic maps) suggest present-day drainage routes in the Cheyenne Tablelands r...Drainage divides along a southern Laramie Range crest area and in the nearby southeast Wyoming Gangplank area (as observed on detailed topographic maps) suggest present-day drainage routes in the Cheyenne Tablelands region originated as headward erosion of south-oriented valleys (now the downstream Lodgepole, Crow, and Lone Tree Creek valleys) from an actively eroding northeast-oriented South Platte River valley captured flood flow in the south half of a large east-oriented anastomosing channel complex while headward erosion of a north-oriented valley (now the downstream Horse Creek valley) from the southeast-oriented North Platte River valley captured the north half of the same large anastomosing channel complex. The Gangplank, which today serves as a low gradient ramp of Tertiary Ogallala Formation sediments leading from the Great Plains to the Laramie Range erosion surface, is located along the Crow Creek-Lone Tree Creek drainage divide and low points along that divide (referred to here as divide crossings) suggest, prior to headward erosion of what is now its south-oriented downstream Lone Tree Creek valley, upstream east-oriented Lone Tree Creek drainage routes were intertwined with east-oriented Crow Creek drainage routes, which today flow much further in an east direction (than east-oriented upstream Lone Tree Creek drainage routes) before also turning in a south direction to reach the South Platte River. The ability of the commonly accepted regional geomorphology paradigm to explain this topographic map evidence is then compared with a fundamentally different and new regional geomorphology paradigm’s ability to explain the same evidence. While both paradigms offer possible explanations the new paradigm, which requires headward erosion of the valleys to have occurred as massive continental ice sheet melt water floods crossed the region, explains much more of the drainage system evidence and also permits much more detailed explanations.展开更多
基金UnitedStateGeologicalSurveyGrant(No.1 4 34 HQ 96 GR 0 2 683)
文摘The authors demonstrate the importance of the simulation of the water quantity exchange between river water and groundwater to a better understanding of the hydrologic relations between a river and nearby aquifer where groundwater is pumped extensively but only seasonally. And MODFLOW is used to design the stream aquifer model in which the pumpage of more than 1000 wells was simulated. The river gaining and river losing processes were analyzed. Simulation results suggest that continuation of over extraction of groundwater will gradually increase the depletion volume in the river year after year and more depletion will occur in later years. The exchange manner between groundwater and the Platte River differs from place to place. The Platte River loses water to the adjacent aquifer in the west part of the study area, and gains water from the adjacent aquifer in the east part of the study area.
文摘In the fall of 2018, Kansas City—the hometown of Edgar Snow,a noted American journalist known throughout China for his strong relationship with the country—held a grand conference to mark the80th anniversary of the publication of Snow’s classic book Red Star Over China. More than 50 experts and scholars from the United States and China gathered on Oct 4 to 6 to remember this old friend of the Chinese people and discuss topics such as USChina relations.
文摘Detailed topographic maps show multiple stream valleys and what are probably dismembered stream valleys that extend completely across Wyoming’s northern Laramie Mountains. Several of the most obvious valleys are described with valley origins first explained (or attempted to be explained) from the commonly accepted regional geomorphology paradigm (accepted paradigm) perspective and second from a recently proposed regional geomorphology paradigm (new paradigm) perspective in an effort to determine which of the two paradigms provides the simplest explanations. Accepted paradigm explanations require at least some of the valley erosion to have occurred prior to deposition of Oligocene and Miocene sediments that once covered the northern Laramie Mountains (with some of the exhumed valleys now containing sediment cover remnants). In contrast the fundamentally different new paradigm requires immense south-oriented continental ice sheet melt water floods to have crossed the region as ice sheet related crustal warping raised the region and the Laramie Mountains (and implies sediments now partially filling some of the valleys are probably flood deposited materials). The new paradigm provides simpler explanations for the origins of the valleys now extending completely across the northern Laramie Mountains and also for their related barbed tributaries, truncated side valleys, and drainage route U-turns than the accepted paradigm, although the new paradigm also leads to a fundamentally different middle and late Cenozoic regional geologic history than is currently recognized. One paradigm cannot be used to judge a different paradigm, but the paradigms can be compared based on their ability to explain evidence and Occam’s Razor can determine which of the two paradigms provides the simplest explanations. New paradigm explanations for northern Laramie Mountains valley origins investigated here require fewer assumptions than the accepted paradigm explanations suggesting the new paradigm merits serious future consideration.
文摘Drainage divides along a southern Laramie Range crest area and in the nearby southeast Wyoming Gangplank area (as observed on detailed topographic maps) suggest present-day drainage routes in the Cheyenne Tablelands region originated as headward erosion of south-oriented valleys (now the downstream Lodgepole, Crow, and Lone Tree Creek valleys) from an actively eroding northeast-oriented South Platte River valley captured flood flow in the south half of a large east-oriented anastomosing channel complex while headward erosion of a north-oriented valley (now the downstream Horse Creek valley) from the southeast-oriented North Platte River valley captured the north half of the same large anastomosing channel complex. The Gangplank, which today serves as a low gradient ramp of Tertiary Ogallala Formation sediments leading from the Great Plains to the Laramie Range erosion surface, is located along the Crow Creek-Lone Tree Creek drainage divide and low points along that divide (referred to here as divide crossings) suggest, prior to headward erosion of what is now its south-oriented downstream Lone Tree Creek valley, upstream east-oriented Lone Tree Creek drainage routes were intertwined with east-oriented Crow Creek drainage routes, which today flow much further in an east direction (than east-oriented upstream Lone Tree Creek drainage routes) before also turning in a south direction to reach the South Platte River. The ability of the commonly accepted regional geomorphology paradigm to explain this topographic map evidence is then compared with a fundamentally different and new regional geomorphology paradigm’s ability to explain the same evidence. While both paradigms offer possible explanations the new paradigm, which requires headward erosion of the valleys to have occurred as massive continental ice sheet melt water floods crossed the region, explains much more of the drainage system evidence and also permits much more detailed explanations.
