Upstream-downstream relationships of annual streamflow discharges and severity and frequency of stream-flow drought events are critical in understanding how streamflow droughts propagate over time and space. Such info...Upstream-downstream relationships of annual streamflow discharges and severity and frequency of stream-flow drought events are critical in understanding how streamflow droughts propagate over time and space. Such information can be used to resolve water disputes, trigger mitigation strategies, and understand how streamflow changes due to changes in the environment. During drought years, such information is even more critical as water resources are contested. The objective of this research is to study the upstream-downstream relationships of streamflow in Nebraska along four major river systems with diverse hydrologic characteris-tics and human activities: North Platte, Big Blue, Republican, and Niobrara. The relationships among the upstream and downstream stations along the four rivers are investigated by comparing several statistics de-rived from the annual flow discharge and on drought events. Trend analysis and coefficient of variation are applied to annual flow discharge values, and a host of drought-related parameters (e.g., annual maximum drought duration, annual accumulated drought duration, number of drought events) are also computed with respect to five different levels of streamflow drought events: water shortage, mild drought, moderate drought, significant drought, and extreme drought. The paired-t test and ANOVA with MIXED procedure are subse-quently applied to the statistics to observe whether there is a significant difference between upstream and downstream stations along a river. The analysis allows us to characterize the upstream-downstream relation-ships of the four river systems, laying the groundwork for further investigations to identify the reasons for some of the trends and observations. These findings will be essential in water resources management during or prior to hydrological droughts.展开更多
A case study is introduced and discussed concerning water dispute of misuse and pollution between up\| and down\|stream parts. The relations between water usage and local industrial structures are analyzed. Results sh...A case study is introduced and discussed concerning water dispute of misuse and pollution between up\| and down\|stream parts. The relations between water usage and local industrial structures are analyzed. Results show it is important to change industrial structures of the target region along with controlling water pollution by technical and engineering methods. Three manners of upstream-downstream cooperation are presented and discussed based on the actual conditions of Guangting Reservoir watershed. Two typical scenarios are supposed and studied along with the local plan on water resources development. The best solution for this cooperation presents a good way to help the upstream developing in a new pattern of eco-economy.展开更多
The North Atlantic Oscillation(NAO),a crucial low-frequency variability mode in the atmospheric circulation of the Northern Hemisphere at mid-to-high latitudes,exhibits an unclear mechanism of influence on the Western...The North Atlantic Oscillation(NAO),a crucial low-frequency variability mode in the atmospheric circulation of the Northern Hemisphere at mid-to-high latitudes,exhibits an unclear mechanism of influence on the Western Tibetan Vortex(WTV).Based on ERA5 reanalysis data,this study elucidates the different impacts of NAO on WTV in summer versus winter.The results demonstrate that:(1)The impacts of the NAO on WTV are the strongest in summer,and stronger NAO events exert a heavier influence on the WTV.(2)The NAO modulates the WTV mainly through influencing the zonal winds north and south of the western Tibetan Plateau(TP):the positive(negative)strong NAO causes the enhanced westerlies(easterlies)on the northern flank and easterlies(westerlies)along the southern flank of the western TP,resulting in an anticyclonic(cyclonic)WTV.(3)The differences in wave energy propagation between summer and winter can explain the seasonal dependence of the impacts of the NAO on the WTV.In summer,wave energy propagates eastward along the westerly jet from the North Atlantic,reaching the western TP,generating anticyclonic/cyclonic circulation anomalies and altering the zonal winds along the western TP's northern and southern flanks,thereby modifying the WTV's circulation structure and intensity.In winter,however,the wave propagation associated with the NAO is stronger between middle and high latitudes in the North Atlantic sector,with less eastward propagation to the TP,resulting in limited influence on the WTV.This study verifies that high-latitude systems influence low-latitude climates through upstreamdownstream effects,providing a foundation for extended-range forecasting of plateau weather systems and responses to climate change.展开更多
文摘Upstream-downstream relationships of annual streamflow discharges and severity and frequency of stream-flow drought events are critical in understanding how streamflow droughts propagate over time and space. Such information can be used to resolve water disputes, trigger mitigation strategies, and understand how streamflow changes due to changes in the environment. During drought years, such information is even more critical as water resources are contested. The objective of this research is to study the upstream-downstream relationships of streamflow in Nebraska along four major river systems with diverse hydrologic characteris-tics and human activities: North Platte, Big Blue, Republican, and Niobrara. The relationships among the upstream and downstream stations along the four rivers are investigated by comparing several statistics de-rived from the annual flow discharge and on drought events. Trend analysis and coefficient of variation are applied to annual flow discharge values, and a host of drought-related parameters (e.g., annual maximum drought duration, annual accumulated drought duration, number of drought events) are also computed with respect to five different levels of streamflow drought events: water shortage, mild drought, moderate drought, significant drought, and extreme drought. The paired-t test and ANOVA with MIXED procedure are subse-quently applied to the statistics to observe whether there is a significant difference between upstream and downstream stations along a river. The analysis allows us to characterize the upstream-downstream relation-ships of the four river systems, laying the groundwork for further investigations to identify the reasons for some of the trends and observations. These findings will be essential in water resources management during or prior to hydrological droughts.
文摘A case study is introduced and discussed concerning water dispute of misuse and pollution between up\| and down\|stream parts. The relations between water usage and local industrial structures are analyzed. Results show it is important to change industrial structures of the target region along with controlling water pollution by technical and engineering methods. Three manners of upstream-downstream cooperation are presented and discussed based on the actual conditions of Guangting Reservoir watershed. Two typical scenarios are supposed and studied along with the local plan on water resources development. The best solution for this cooperation presents a good way to help the upstream developing in a new pattern of eco-economy.
基金National Natural Science Foundation of China(42088101,42175026,42175080,42475036)the Innovation Group of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2023SP209)Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies(2023B1212060019)。
文摘The North Atlantic Oscillation(NAO),a crucial low-frequency variability mode in the atmospheric circulation of the Northern Hemisphere at mid-to-high latitudes,exhibits an unclear mechanism of influence on the Western Tibetan Vortex(WTV).Based on ERA5 reanalysis data,this study elucidates the different impacts of NAO on WTV in summer versus winter.The results demonstrate that:(1)The impacts of the NAO on WTV are the strongest in summer,and stronger NAO events exert a heavier influence on the WTV.(2)The NAO modulates the WTV mainly through influencing the zonal winds north and south of the western Tibetan Plateau(TP):the positive(negative)strong NAO causes the enhanced westerlies(easterlies)on the northern flank and easterlies(westerlies)along the southern flank of the western TP,resulting in an anticyclonic(cyclonic)WTV.(3)The differences in wave energy propagation between summer and winter can explain the seasonal dependence of the impacts of the NAO on the WTV.In summer,wave energy propagates eastward along the westerly jet from the North Atlantic,reaching the western TP,generating anticyclonic/cyclonic circulation anomalies and altering the zonal winds along the western TP's northern and southern flanks,thereby modifying the WTV's circulation structure and intensity.In winter,however,the wave propagation associated with the NAO is stronger between middle and high latitudes in the North Atlantic sector,with less eastward propagation to the TP,resulting in limited influence on the WTV.This study verifies that high-latitude systems influence low-latitude climates through upstreamdownstream effects,providing a foundation for extended-range forecasting of plateau weather systems and responses to climate change.
