Efforts to restore urban rivers require an understanding of human-influenced changes in channel substrates. This study uses three naturally-occurring oxbows in a 3.5 km reach of Swan Creek, flowing through the City of...Efforts to restore urban rivers require an understanding of human-influenced changes in channel substrates. This study uses three naturally-occurring oxbows in a 3.5 km reach of Swan Creek, flowing through the City of Toledo, Ohio (USA) to reconstruct historical changes in channel substrate. Human impacts in the watershed were: 1) land clearance for agriculture (peaking in 1900-1920) and for suburban housing tracts (peaking in 1945-1970), followed by 2) the post-1940 creation of more efficient urban run-off systems from streets, parking lots, housing developments, and shopping centers. Historical aerial photographs and maps from 1935, 1940, 1950, 1963, 1974, and 1994 were georeferenced using ground control points, input to ArcGIS, and have root mean square error (RMSE) ranging from 0.19 - 0.77 m (average RMSE = 0.47 ± 0.20 m) when compared to the 2006 digital ortho quarter-quadrangle (DOQQ) image used as the basis for comparison. Results showed that channel sinuosity continually increased from 1.88 (1935) to 1.99 (2006). Two oxbows probably formed in 1913, and the third formed in 1940. Sediment cores and trenches were used to recognize historical channel substrates. Age control was provided by <sup>14</sup>C geochronology and labels on food packaging materials found in flood layers. Grain-size analysis of channel substrates shows a historical coarsening-upward trend: the largest clast size interval (f<sub>5</sub>) changes from +0.78f in pre-1935 channels, to -1.15f in pre-1940 channels, to -1.69f in the 2006 channel. These results indicate recent urban runoff created fluvial pavements and increasing channel mobility as the stream removes legacy sediment from intrabasinal sediment storage.展开更多
Climate changes are one of the most significant aspects, which cause a threat to all human beings living on the planet Earth. Climate changes could happen due to both natural internal processes and external forcing, o...Climate changes are one of the most significant aspects, which cause a threat to all human beings living on the planet Earth. Climate changes could happen due to both natural internal processes and external forcing, or due to persistent anthropogenic changes. The identified drastic temperature changes, increase in the emitted greenhouse gasses, and sea-level changes as witnessed from the acquired data;such as from ice cores, during the past centuries and even decades are all due to climate changes. Due to the increase in the emitted greenhouse gasses, major sectors in the Earth will be hit severely, such as agriculture and industry. Human welfare and health services will consequently suffer and development, in general, is going to be hampered. Large parts of the Earth will be unfavorable for living due to different reasons;such as inundation by seawater, decrease in temperature;however, some scientists believe that the increase in the percentages of the emitted greenhouse gasses has decreased or delayed the possibility of starting a new ice age. We have presented all possible scenarios, which may happen due to climate changes including temperature changes, emitted greenhouse gasses, sea level, and other harsh effects not only on human beings but all other living animal and plant species.展开更多
Sea level rise （SLR） is a major projected threat of climate change that is expected to affect developing coastal cities located in estuarine delta regions, Shanghai is one such city, being located in the Yangtze Riv...Sea level rise （SLR） is a major projected threat of climate change that is expected to affect developing coastal cities located in estuarine delta regions, Shanghai is one such city, being located in the Yangtze River Delta （YRD）, It is difficult, however, for decision-makers to implement adaptation due to the uncer- tain causes, magnitudes, and timings of SLR behaviors, This paper attempts to map the causes and mag- nitudes of SLR behaviors on a decadal scale, We analyze the tidal level records from 11 tidal gauge stations and the corresponding bathymetry measurements around these stations since 1921, We identify three new SLR behaviors along the Shanghai coast due to anthropogenic geomorphologic changes （AGCs）, besides the well-known eustatic sea level rise （ESLR）, tectonic subsidence （TS）, and urban land subsidence （ULS）, The first new behavior is regional sea level rise （RSLR）, which occurs as a result of land reclamation and deep waterway regulation, The second is regional sea level fall （RSLF）, which occurs because the channel bed is eroded due to sediment supply decline in the river catchment, The last SLR behavior is local tidal datum rise （LTDR）. Thus, we project that the magnitude of SLR for the Shanghai coast ranges from 10 cm to 16 cm from 2011 to 2030, Clarifying SLR behaviors is important to aid local decision- makers in planning structural and non-structural measures to combat escalating flood damage costs in an estuarine delta system; this field is full of future challenges,展开更多
In this paper the authors perform an extensive sensitivity analysis of the Indian summer monsoon rainfall to changes in parameters and boundary conditions which are influenced by human activities. For this study the a...In this paper the authors perform an extensive sensitivity analysis of the Indian summer monsoon rainfall to changes in parameters and boundary conditions which are influenced by human activities. For this study the authors use a box model of the Indian monsoon which reproduces key features of the observed monsoon dynamics such as the annual course of precipitation and the transitions between winter and summer regimes. Because of its transparency and computational efficiency, this model is highly suitable for exploring the effects of anthropogenic perturbations such as emissions of greenhouse gases and sulfur dioxide, and land cover changes, on the Indian monsoon. Results of a systematic sensitivity analysis indicate that changes in those parameters which are related to emissions of greenhouse gases lead to an increase in Indian summer rainfall. In contrast, all parameters related to higher atmospheric aerosol concentrations lead to a decrease in Indian rainfall. Similarly, changes in parameters which can be related to forest conversion or desertifieation, act to decrease the summer precipitation. The results indicate that the sign of precipitation changes over India will be dependent on the direction and relative magnitude of different human perturbations.展开更多
Today anthropogenic climate change is underway and predicted future global temperatures vary significantly. However, the drivers of current climate change and their links to Earth’s natural glacial cycle have yet to ...Today anthropogenic climate change is underway and predicted future global temperatures vary significantly. However, the drivers of current climate change and their links to Earth’s natural glacial cycle have yet to be fully resolved. Currently, many on a local level understand, and are exposed to, the heat energy generated by what’s referred to as the urban heat island effect (UHI), whereby natural flora with higher albedos </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> replaced by manmade urban areas with lower albedos. This heat effect is not constrained to these regions and all anthropogenic surfaces with lower albedos need to be studied and quantified as the accumulated additional heat energy (infrared energy) is trapped within Earth’s atmosphere and could affect the Earth on a planetary level. Deployed satellites have detected critical changes to Earth’s albedo to lower levels, however the cause and impact of these changes have yet to be fully understood and incorporated into Global Circulation models (GCMs). Here it’s shown that industrialization of anthropogenic landscape practices of the past century has displaced millions of square kilometres of naturally high albedo grasslands with lower albedo agricultural landscapes. Utilising a fundamental Energy Balance Model, (EBM) it’s demonstrated these specific changes have generated vast amounts of additional heat energy which is trapped by the atmosphere, transferred and stored within the oceans of the Earth as shown in <b></span></span></span><a href="file:///E:/360data/%E9%87%8D%E8%A6%81%E6%95%B0%E6%8D%AE/%E6%A1%8C%E9%9D%A2/%E7%A9%BA%E7%99%BD%E9%A1%B5.docx#F1"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Figure 1</span></b></span></span></a><span style="font-family:Verdana;"><span style展开更多
文摘Efforts to restore urban rivers require an understanding of human-influenced changes in channel substrates. This study uses three naturally-occurring oxbows in a 3.5 km reach of Swan Creek, flowing through the City of Toledo, Ohio (USA) to reconstruct historical changes in channel substrate. Human impacts in the watershed were: 1) land clearance for agriculture (peaking in 1900-1920) and for suburban housing tracts (peaking in 1945-1970), followed by 2) the post-1940 creation of more efficient urban run-off systems from streets, parking lots, housing developments, and shopping centers. Historical aerial photographs and maps from 1935, 1940, 1950, 1963, 1974, and 1994 were georeferenced using ground control points, input to ArcGIS, and have root mean square error (RMSE) ranging from 0.19 - 0.77 m (average RMSE = 0.47 ± 0.20 m) when compared to the 2006 digital ortho quarter-quadrangle (DOQQ) image used as the basis for comparison. Results showed that channel sinuosity continually increased from 1.88 (1935) to 1.99 (2006). Two oxbows probably formed in 1913, and the third formed in 1940. Sediment cores and trenches were used to recognize historical channel substrates. Age control was provided by <sup>14</sup>C geochronology and labels on food packaging materials found in flood layers. Grain-size analysis of channel substrates shows a historical coarsening-upward trend: the largest clast size interval (f<sub>5</sub>) changes from +0.78f in pre-1935 channels, to -1.15f in pre-1940 channels, to -1.69f in the 2006 channel. These results indicate recent urban runoff created fluvial pavements and increasing channel mobility as the stream removes legacy sediment from intrabasinal sediment storage.
文摘Climate changes are one of the most significant aspects, which cause a threat to all human beings living on the planet Earth. Climate changes could happen due to both natural internal processes and external forcing, or due to persistent anthropogenic changes. The identified drastic temperature changes, increase in the emitted greenhouse gasses, and sea-level changes as witnessed from the acquired data;such as from ice cores, during the past centuries and even decades are all due to climate changes. Due to the increase in the emitted greenhouse gasses, major sectors in the Earth will be hit severely, such as agriculture and industry. Human welfare and health services will consequently suffer and development, in general, is going to be hampered. Large parts of the Earth will be unfavorable for living due to different reasons;such as inundation by seawater, decrease in temperature;however, some scientists believe that the increase in the percentages of the emitted greenhouse gasses has decreased or delayed the possibility of starting a new ice age. We have presented all possible scenarios, which may happen due to climate changes including temperature changes, emitted greenhouse gasses, sea level, and other harsh effects not only on human beings but all other living animal and plant species.
基金This study was financially supported by the National Natural Science Foundation of China-the Netherlands Organization for Scientific Research-Research Councils UK （NSFC-NWO-RCUK） （51761135023）, the Shanghai Science and Technology Committee （10dz1210600）, the National Sea Welfare Project （201005019- 09）, the National Natural Science Foundation of China （41476075）, and the China Geological Survey （DD20160246）. We would like to give a special acknowledgement to the second author, ProfessorJi-Yu Chen, who was a great scientist of estuarine and coastal research, for the excellent suggestions and guidelines he provided over a considerable period of time before he passed away.
文摘Sea level rise （SLR） is a major projected threat of climate change that is expected to affect developing coastal cities located in estuarine delta regions, Shanghai is one such city, being located in the Yangtze River Delta （YRD）, It is difficult, however, for decision-makers to implement adaptation due to the uncer- tain causes, magnitudes, and timings of SLR behaviors, This paper attempts to map the causes and mag- nitudes of SLR behaviors on a decadal scale, We analyze the tidal level records from 11 tidal gauge stations and the corresponding bathymetry measurements around these stations since 1921, We identify three new SLR behaviors along the Shanghai coast due to anthropogenic geomorphologic changes （AGCs）, besides the well-known eustatic sea level rise （ESLR）, tectonic subsidence （TS）, and urban land subsidence （ULS）, The first new behavior is regional sea level rise （RSLR）, which occurs as a result of land reclamation and deep waterway regulation, The second is regional sea level fall （RSLF）, which occurs because the channel bed is eroded due to sediment supply decline in the river catchment, The last SLR behavior is local tidal datum rise （LTDR）. Thus, we project that the magnitude of SLR for the Shanghai coast ranges from 10 cm to 16 cm from 2011 to 2030, Clarifying SLR behaviors is important to aid local decision- makers in planning structural and non-structural measures to combat escalating flood damage costs in an estuarine delta system; this field is full of future challenges,
基金the German Research Association (DFG) (PR1175/1-1)
文摘In this paper the authors perform an extensive sensitivity analysis of the Indian summer monsoon rainfall to changes in parameters and boundary conditions which are influenced by human activities. For this study the authors use a box model of the Indian monsoon which reproduces key features of the observed monsoon dynamics such as the annual course of precipitation and the transitions between winter and summer regimes. Because of its transparency and computational efficiency, this model is highly suitable for exploring the effects of anthropogenic perturbations such as emissions of greenhouse gases and sulfur dioxide, and land cover changes, on the Indian monsoon. Results of a systematic sensitivity analysis indicate that changes in those parameters which are related to emissions of greenhouse gases lead to an increase in Indian summer rainfall. In contrast, all parameters related to higher atmospheric aerosol concentrations lead to a decrease in Indian rainfall. Similarly, changes in parameters which can be related to forest conversion or desertifieation, act to decrease the summer precipitation. The results indicate that the sign of precipitation changes over India will be dependent on the direction and relative magnitude of different human perturbations.
文摘Today anthropogenic climate change is underway and predicted future global temperatures vary significantly. However, the drivers of current climate change and their links to Earth’s natural glacial cycle have yet to be fully resolved. Currently, many on a local level understand, and are exposed to, the heat energy generated by what’s referred to as the urban heat island effect (UHI), whereby natural flora with higher albedos </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> replaced by manmade urban areas with lower albedos. This heat effect is not constrained to these regions and all anthropogenic surfaces with lower albedos need to be studied and quantified as the accumulated additional heat energy (infrared energy) is trapped within Earth’s atmosphere and could affect the Earth on a planetary level. Deployed satellites have detected critical changes to Earth’s albedo to lower levels, however the cause and impact of these changes have yet to be fully understood and incorporated into Global Circulation models (GCMs). Here it’s shown that industrialization of anthropogenic landscape practices of the past century has displaced millions of square kilometres of naturally high albedo grasslands with lower albedo agricultural landscapes. Utilising a fundamental Energy Balance Model, (EBM) it’s demonstrated these specific changes have generated vast amounts of additional heat energy which is trapped by the atmosphere, transferred and stored within the oceans of the Earth as shown in <b></span></span></span><a href="file:///E:/360data/%E9%87%8D%E8%A6%81%E6%95%B0%E6%8D%AE/%E6%A1%8C%E9%9D%A2/%E7%A9%BA%E7%99%BD%E9%A1%B5.docx#F1"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Figure 1</span></b></span></span></a><span style="font-family:Verdana;"><span style
