This study investigates the multifaceted impacts of climate change on the Midwest region of the United States, particularly the rising temperatures and precipitation brought about by hot weather activities and technol...This study investigates the multifaceted impacts of climate change on the Midwest region of the United States, particularly the rising temperatures and precipitation brought about by hot weather activities and technological advances since the 19th century. From 1900 to 2010, temperatures in the Midwest rose by an average of 1.5 degrees Fahrenheit, which would also lead to an increase in greenhouse gas emissions. Precipitation is also expected to increase due to increased storm activity and changes in regional weather patterns. This paper explores the impact of these changes on urban and agricultural areas. In urban areas such as the city of Chicago, runoff from the increasing impervious surface areas poses challenges to the drainage system, and agriculture areas are challenged by soil erosion, nutrient loss, and fewer planting days due to excessive rainfall. Sustainable solutions such as no-till agriculture and the creation of grassland zones are discussed. Using historical data, recent climate studies and projections, the paper Outlines ways to enhance the Midwest’s ecology and resilience to climate change.展开更多
For recent years,runoff generation and hydrological processes in Hailiutu River basin have been greatly changed by climate change and human activity,especially water and soil conservation construction.In this study,th...For recent years,runoff generation and hydrological processes in Hailiutu River basin have been greatly changed by climate change and human activity,especially water and soil conservation construction.In this study,the trends in precipitation,evapotranspiration(ET)and river runoff as well as the effects of precipitation change and human activity on runoff variation have been studied.The results showed that during 1960-2000,annual precipitation and river runoff,monthly precipitation and ET in September and October as well as monthly runoff in all months showed a significant decrease.In addition,peak flow and base flow had a large decrease.Under the joint influence of precipitation change and human activity,the mean annual runoff decreased by 35 million m3 from the baseline period(1960-1985)to the change period(1986-2000),which accounted for 60.9%and 39.1%of the total runoff decrease,respectively.Precipitation change played a primary role in the decrease of annual runoff whereas human activity,particularly water and soil conservation construction,also had remarkable impacts on runoff variation.展开更多
The precipitation responses to the radiative effects of ice clouds are investigated through analysis of five-day and hori- zontally averaged data from 2D cumulus ensemble model experiments of a pre-summer torrential p...The precipitation responses to the radiative effects of ice clouds are investigated through analysis of five-day and hori- zontally averaged data from 2D cumulus ensemble model experiments of a pre-summer torrential precipitation event. The exclusion of the radiative effects of ice clouds lowered the precipitation rate through a substantial reduction in the decrease of hydrometeors when the radiative effects of water clouds were switched on, whereas it increased the precipitation rate through hydrometeor change from an increase to a decrease when the radiative effects of ice clouds were turned off. The weakened hydrometeor decrease was associated with the enhanced longwave radiative cooling mainly through the decreases in the melt- ing of non-precipitating ice to non-precipitating water. The hydrometeor change from an increase to a decrease corresponded to the strengthened longwave radiative cooling in the upper troposphere through the weakened collection of non-precipitating water by precipitation water.展开更多
This paper analyzed the data of temperature and precipitation in Turpan and Nantong, in the west and east of China, respectively, during the period of 1961 -2007 by linear growth rate, moving average methods, Mann-Ken...This paper analyzed the data of temperature and precipitation in Turpan and Nantong, in the west and east of China, respectively, during the period of 1961 -2007 by linear growth rate, moving average methods, Mann-Kendall nonparametric and moving Ttests. The result indicated that the annual average temperature in Turpan had a linear growth rate of 0.42 ℃/10 a, while the annual average temperature in Nantong had a linear tendency of 0.48 ℃/10 a. The annual average maximum temperature in Turpan with linear growth rate of 0.16 ℃10 a was lower than 0.56 ℃/ 10 a of Nantong, and the annual average minimum temperature in Turpan with linear growth rate of 0.86℃/10 a was higher than 0.70℃/10 a of Nantong. The annual average temperature of Turpan increasing was 7 years earlier than Nantong. The annual average maximum temperature of Turpan increasing was 5 years later than Nantong. The annual average minimum temperature of Turpan increased as same as Nantong in 1986, but the curve showed different process completely. The abrupt change year of average temperature between Turpan and Nantong were same in 1996, and the abrupt change year of average maximum temperature of Turpan was 5 years later than Nantong. For precipitation, Turpan and Nantong had the same trend of increased and decreased. The reason of almost identical trend of temperature and precipitation between Turpan and Nantong may be urbanization and population increasing influencing climate change in a small area.展开更多
Climate change in the Middle East area including Jordan has started to be reflected in decreasing precipitation and increasing temperatures with their impacts on the availability of surface and groundwater. This artic...Climate change in the Middle East area including Jordan has started to be reflected in decreasing precipitation and increasing temperatures with their impacts on the availability of surface and groundwater. This article aims to evaluate the impacts of decreasing or increasing precipitation by 10% and 20% on the quantities of flood runoff based on recorded precipitation and runoffs of catchments during the past 60 to 70 years of observation, during which the precipitation in individual or a few years increased or decreased by tens of percentages relative to the long-term average precipitation. The results of quantification show that in Jordan as a whole, decreasing precipitation by 10% and 20% has historically (during the recording period) resulted in reductions in flood flows by 26.2% and 52.8% and that increasing precipitation by 10% and 20% has resulted in increases in flood flows by 26.4% and 56.5% respectively. These results look somehow paradox, because the general perception is that flood runoff changes in the same percentage like precipitation although flood flow is not linearly correlated with precipitation but exponentially. Decreasing precipitation in the water-scarce stressed country, Jordan due to climatic changes, will have strong implications on rain-fed and irrigated agriculture and on household water supplies with very severe socio-economic percussions expressed in increasing unemployment and poverty which may lead to social and political unrest. Therefore, proactive measures have to be implemented before disasters hit. Such measures are limited in Jordan to seawater desalination, intensified water harvesting and improved water use efficiency in agriculture.展开更多
Based on the observation data of the average temperature and precipitation of 8 national meteorological stations in the northwest region of Liaoning Province from April to October during 1961-2015,methods such as line...Based on the observation data of the average temperature and precipitation of 8 national meteorological stations in the northwest region of Liaoning Province from April to October during 1961-2015,methods such as linear trend estimation,moving average,standard deviation and Mann-Kendall test are used to analyze the characteristics of average temperature and precipitation during the crop growing season in northwestern Liaoning.The results show that the average temperature during the crop growing season in the study area showed an upward trend,and the climate tendency rate was 0.193 ℃/10 a( P < 0.01).The largest contribution rate to temperature increase was in September,with a climate tendency rate of 0.27 ℃/10 a;the smallest contribution rate to the temperature increase was in July,with a climate tendency rate of 0.10 ℃/10 a.The warming trend was the most obvious in the second base year,with a climate tendency rate of 0.413 ℃/10 a( P < 0.01).The temperature was the lowest in the 1970s and the highest in the 2010s.The warming trend changed suddenly in 1996,and the sudden change reached a significant level of α = 0.05 after 2002.Precipitation was generally decreased,and the climate tendency rate was -7.68 mm/10 a.The decrease in precipitation was the most in July,and the climate tendency rate was -12.08 mm/10 a.The average temperature in the four base years failed to pass the correlation significance test.Among them,it showed an increasing trend in the second and third base year and a decreasing trend in the first and fourth base year.Rainfall was the highest in the 1960s and the lowest in the 1980s.After the abrupt change in 2002,precipitation decreased significantly.The research results provide reference for effective utilization of climate resources,rational adjustment of agricultural planting structure,and improvement of ecological environment quality.展开更多
Climate change means water change, and the impacts of climate change cause not only global sea levels to rise, but also elicit dangerous levels of coastal and mainland flooding. This study relates the effects of clima...Climate change means water change, and the impacts of climate change cause not only global sea levels to rise, but also elicit dangerous levels of coastal and mainland flooding. This study relates the effects of climate-change-induced sea level risings to several harmful, and sometimes preventable, factors causing floods. One topic discussed here will be the ocean’s current (more specifically, “The Atlantic Meridional Overturning Current”) as it continues to warm with increasing temperatures. In addition to discussing the effects of the AMOC, it also relates the increasing causes that are contributing to flooding, plus the proliferation of melt from ice sheets, ice caps, and glaciers, which inevitably contributes to the devastating effects of flooding on coastal communities, destroying habitats and contributing to the extinction of both aquatic and land animals, and even impacting human infrastructure and livelihoods. This examination additionally presents the serious implications that climate change and flooding have had on the planet’s freshwater resources and reserves, which are being further destroyed by the added influx of salt water, causing water to then be treated with aquifers, an energy-intensive and highly expensive process. Lastly, this paper provides several suggested possibilities for curbing some of the harmful effects humans have already had on contributing to climate change, as well as the environmental factors that have further caused dangerous levels of flooding.展开更多
This paper describes 2007/2008 inter-annual changes in runoff from the Zhadang Glacier located on the northern slope of Nyainqêntanglha Range,Tibet,and analyzes their causes.Precipitation increased by 17.9%in sum...This paper describes 2007/2008 inter-annual changes in runoff from the Zhadang Glacier located on the northern slope of Nyainqêntanglha Range,Tibet,and analyzes their causes.Precipitation increased by 17.9%in summer months of 2008 compared with the same period in 2007,drainage basin runoff decreased by 33.3%,and glacial meltwater decreased by 53.8%.Change in positive accumulated air temperature explained approximately half of the inter-annual difference in glacial meltwater using a degree-day model.This suggests that the glacier is extremely sensitive to changes in air temperature.Energy balance analysis showed that change in glacier surface albedo,considered to be caused by difference in precipitation form,resulted in the large inter-annual difference in glacial meltwater.It was shown statistically that precipitation form in the summer months of 2007 was mainly rainfall which comprised 71.5%of total precipitation,while during the same period in 2008 rainfall accounted for 30.7%,with the majority of precipitation falling as snow.Precipitation form should be considered an independent factor when analyzing glacier sensitivity to climate change or forecasting the runoff from certain glaciers.展开更多
The effects of land use and land cover(LULC)on groundwater recharge and surface runoff and how these are affected by LULC changes are of interest for sustainable water resources management.However,there is limited qua...The effects of land use and land cover(LULC)on groundwater recharge and surface runoff and how these are affected by LULC changes are of interest for sustainable water resources management.However,there is limited quantitative evidence on how changes to LULC in semi-arid tropical and subtropical regions affect the subsurface components of the hydrologic cycle,particularly groundwater recharge.Effective water resource management in these regions requires conclusive evidence and understanding of the effects of LULC changes on groundwater recharge and surface runoff.We reviewed a total of 27 studies(2 modeling and 25 experimental),which reported on pre-and post land use change groundwater recharge or surface runoff magnitude,and thus allowed to quantify the response of groundwater recharge rates and runoff to LULC.Comparisons between initial and subsequent LULC indicate that forests have lower groundwater recharge rates and runoff than the other investigated land uses in semi-arid tropical/subtropical regions.Restoration of bare land induces a decrease in groundwater recharge from 42% of precipitation to between 6 and 12% depending on the final LULC.If forests are cleared for rangelands,groundwater recharge increases by 7.8±12.6%,while conversion to cropland or grassland results in increases of 3.4±2.5 and 4.4±3.3%,respectively.Rehabilitation of bare land to cropland results in surface runoff reductions of between 5.2 and 7.3%.The conversion of forest vegetation to managed LULC shows an increase in surface runoff from 1 to 14.1% depending on the final LULC.Surface runoff was reduced from 2.5 to 1.1% when grassland is converted to forest vegetation.While there is general consistency in the results from the selected case studies,we conclude that there are few experimental studies that have been conducted in tropical and subtropical semi-arid regions,despite that many people rely heavily on groundwater for their livelihoods.Therefore,there is an urgent need to increase the body of quantitative evidence given the pressure of growing human population and climate change on water resources in the region.展开更多
The global distributions of the rate of precipitation change at seasonal, interannual and interdecadal scales are computed from the observed global data sets. The analysis has revealed that the monsoon regions in Asia...The global distributions of the rate of precipitation change at seasonal, interannual and interdecadal scales are computed from the observed global data sets. The analysis has revealed that the monsoon regions in Asia and West Africa, and to lesser extent Australia, have the highest rate of precipitation change at all time scales in the world. These changes are manifested as seasonal jump, high interannual and interdecadal variability and abrupt changes between climate regimes.展开更多
The runoff of some rivers in the world especially in the arid and semi-arid areas has decreased remarkably with global or regional climate change and enhanced human activities. The runoff decrease in the arid and semi...The runoff of some rivers in the world especially in the arid and semi-arid areas has decreased remarkably with global or regional climate change and enhanced human activities. The runoff decrease in the arid and semi-arid areas of northern China has brought severe problems in livelihoods and ecology. To reveal the variation characteristics, trends of runoff and their influencing factors have been important scientific issues for drainage basin man- agement. The objective of this study was to analyze the variation trends of the runoff and quantitatively assess the contributions of precipitation and human activities to the runoff change in the Huangfuchuan River Basin based on the measured data in 1960-2008. Two inflection points (turning years) of 1979 and 1998 for the accumulative runoff change, and one inflection point of 1979 for the accumulative precipitation change were identified using the methods of accumulative anomaly analysis. The linear relationships between year and ac- cumulative runoff in 1960-1979, 1980-1997 and 1998-2008 and between year and accu- mulative precipitation in 1960-1979 and 1980-2008 were fitted. A new method of slope change ratio of accumulative quantity (SCRAQ) was put forward and used in this study to calculate the contributions of different factors to the runoff change. Taking 1960-1979 as the base period, the contribution rate of the precipitation and human activities to the decreased runoff was 36.43% and 63.57% in 1980-1997, and 16.81% and 83.19% in 1998-2008, re- spectively. The results will play an important role in the drainage basin management. More- over, the new method of SCRAQ can be applied in the quantitative evaluation of runoff change and impacts by different factors in the river basin of arid and semi-arid areas.展开更多
Runoffs in the Yellow River and Yangtze River basins,China,have been changing constantly during the last half century.In this paper,data from eight river gauging stations and 529 meteorological stations,inside and adj...Runoffs in the Yellow River and Yangtze River basins,China,have been changing constantly during the last half century.In this paper,data from eight river gauging stations and 529 meteorological stations,inside and adjacent to the study basins,were analyzed and compared to quantify the hydrological processes involved,and to evaluate the role of human activities in changing river discharges.The Inverse Distance Weighted(IDW)interpolation method was used to obtain climatic data coverage from station observations.According to the runoff coefficient equation,the effect of human activities and climate can be expressed by changes in runoff coefficients and changes in precipitation,respectively.Annual runoff coefficients were calculated for the period 1950-2008,according to the correlation between respective hydrological series and regional precipitation.Annual precipitation showed no obvious trend in the upper reaches of the Yellow River but a marked downward trend in the middle and downstream reaches,with declines of 8.8 and 9.8 mm/10 a,respectively.All annual runoff series for the Yellow River basin showed a significant downward trend.Runoff declined by about 7.8 mm/10 a at Sanmenxia and 10.8 mm/10 a at Lijin.The series results indicated that an abrupt change occurred in the late 1980s to early 1990s.The trend of correlations between annual runoff and precipitation decreased significantly at the Yellow River stations,with rates ranging from 0.013/10 a to 0.019/10 a.For the hydrologic series,all precipitation series showed a downward trend in the Yangtze River basin with declines ranging from about 24.7 mm/10 a at Cuntan to 18.2 mm/10 a at Datong.Annual runoff series for the upper reaches of the Yangtze River decreased significantly,at rates ranging from 9.9 to 7.2 mm/10 a.In the middle and lower reaches,the runoff series showed no significant trend,with rates of change ranging from 2.1 to 2.9 mm/10 a.Human activities had the greatest influence on changes in the hydrological series of runoff,regardless of whether the effect was negative or positive.During 1970-2008,human activities contributed to 83% of the reduction in runoff in the Yellow River basin,and to 71% of the increase in runoff in the Yangtze River basin.Moreover,the impacts of human activities across the entire basin increased over time.In the 2000s,the impact of human activities exceeded that of climate change and was responsible for 84% of the decrease and 73% of the increase in runoff in the Yellow River and Yangtze River basins,respectively.The average annual runoff from 1980 to 2008 fell by about 97%,83%,83%,and 91%,compared with 1951-1969,at the Yellow River stations Lanzhou,Sanmenxia,Huayuankou and Lijin,respectively.Most of the reduction in runoff was caused by human activities.Changes in precipitation also caused reductions in runoff of about 3%,17%,17%,and 9% at these four stations,respectively.Falling precipitation rates were the main explanation for runoff changes at the Yangtze River stations Cuntan,Yichang,Hankou,and Datong,causing reductions in runoff of 89%,74%,43%,and 35%,respectively.Underlying surface changes caused decreases in runoff in the Yellow River basin and increases in runoff in the Yangtze River basin.Runoff decreased in arid areas as a result of increased water usage,but increased in humid and sub-humid areas as a result of land reclamation and mass urbanization leading to decreases in evaporation and infiltration.展开更多
Climate change and land use/cover change(LUCC)can both exert great impacts on the generation processes of precipitation and runoff.However,previous studies usually neglected considering the contribution component of f...Climate change and land use/cover change(LUCC)can both exert great impacts on the generation processes of precipitation and runoff.However,previous studies usually neglected considering the contribution component of future LUCC in evaluating changes in hydrological cycles.In this study,an integrated framework is developed to quantify and partition the impact of climate change and LUCC on future runoff evolution.First,a daily bias correction(DBC)method and the Cellular Automaton-Markov(CA-Markov)model are used to project future climate and LUCC scenarios,and then future runoff is simulated by the calibrated Soil and Water Assessment Tool(SWAT)model with different climate and LUCC scenarios.Finally,the uncertainty of future runoff and the contribution rate of the two driving factors are systematically quantified.The Han River basin in China was selected as a case study.Results indicate that:1)both climate change and LUCC will contribute to future runoff intensification,the variation of future runoff under combined climate and LUCC is larger than these under climate change or LUCC alone;2)the projected uncertainty of median value of multi-models under RCP4.5(RCP8.5)will reach 18.14%(20.34%),12.18%(14.71%),11.01%(13.95%),and 11.41%(14.34%)at Baihe,Ankang,Danjiangkou,and Huangzhuang stations,respectively;3)the contribution rate of climate change to runoff at Baihe,Ankang,Danjiangkou,and Huangzhuang stations under RCP4.5(RCP8.5)are 91%-98%(84%-94%),while LUCC to runoff under RCP4.5(RCP8.5)only accounts for 2%-9%(6%-16%)in the annual scale.This study may provide useful adaptive strategies for policymakers on future water resources planning and management.展开更多
文摘This study investigates the multifaceted impacts of climate change on the Midwest region of the United States, particularly the rising temperatures and precipitation brought about by hot weather activities and technological advances since the 19th century. From 1900 to 2010, temperatures in the Midwest rose by an average of 1.5 degrees Fahrenheit, which would also lead to an increase in greenhouse gas emissions. Precipitation is also expected to increase due to increased storm activity and changes in regional weather patterns. This paper explores the impact of these changes on urban and agricultural areas. In urban areas such as the city of Chicago, runoff from the increasing impervious surface areas poses challenges to the drainage system, and agriculture areas are challenged by soil erosion, nutrient loss, and fewer planting days due to excessive rainfall. Sustainable solutions such as no-till agriculture and the creation of grassland zones are discussed. Using historical data, recent climate studies and projections, the paper Outlines ways to enhance the Midwest’s ecology and resilience to climate change.
基金financially supported by National Natural Science Foundation of China[grant number 50239050],[grantnumber 40571029],[grant number 40901028]
文摘For recent years,runoff generation and hydrological processes in Hailiutu River basin have been greatly changed by climate change and human activity,especially water and soil conservation construction.In this study,the trends in precipitation,evapotranspiration(ET)and river runoff as well as the effects of precipitation change and human activity on runoff variation have been studied.The results showed that during 1960-2000,annual precipitation and river runoff,monthly precipitation and ET in September and October as well as monthly runoff in all months showed a significant decrease.In addition,peak flow and base flow had a large decrease.Under the joint influence of precipitation change and human activity,the mean annual runoff decreased by 35 million m3 from the baseline period(1960-1985)to the change period(1986-2000),which accounted for 60.9%and 39.1%of the total runoff decrease,respectively.Precipitation change played a primary role in the decrease of annual runoff whereas human activity,particularly water and soil conservation construction,also had remarkable impacts on runoff variation.
基金supported by the National Key Basic Research and Development Project of China(Grant Nos.2013CB430103 and 2015CB453201)the National Natural Science Foundation of China(Grant Nos.41375058 and 41530427)+1 种基金Jiangsu Natural Science Key Project(Grant No.BK20150062)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The precipitation responses to the radiative effects of ice clouds are investigated through analysis of five-day and hori- zontally averaged data from 2D cumulus ensemble model experiments of a pre-summer torrential precipitation event. The exclusion of the radiative effects of ice clouds lowered the precipitation rate through a substantial reduction in the decrease of hydrometeors when the radiative effects of water clouds were switched on, whereas it increased the precipitation rate through hydrometeor change from an increase to a decrease when the radiative effects of ice clouds were turned off. The weakened hydrometeor decrease was associated with the enhanced longwave radiative cooling mainly through the decreases in the melt- ing of non-precipitating ice to non-precipitating water. The hydrometeor change from an increase to a decrease corresponded to the strengthened longwave radiative cooling in the upper troposphere through the weakened collection of non-precipitating water by precipitation water.
基金Supported by Doctor Degree Foundation of Xi'an University of Science and Technology(2012QDJ029)
文摘This paper analyzed the data of temperature and precipitation in Turpan and Nantong, in the west and east of China, respectively, during the period of 1961 -2007 by linear growth rate, moving average methods, Mann-Kendall nonparametric and moving Ttests. The result indicated that the annual average temperature in Turpan had a linear growth rate of 0.42 ℃/10 a, while the annual average temperature in Nantong had a linear tendency of 0.48 ℃/10 a. The annual average maximum temperature in Turpan with linear growth rate of 0.16 ℃10 a was lower than 0.56 ℃/ 10 a of Nantong, and the annual average minimum temperature in Turpan with linear growth rate of 0.86℃/10 a was higher than 0.70℃/10 a of Nantong. The annual average temperature of Turpan increasing was 7 years earlier than Nantong. The annual average maximum temperature of Turpan increasing was 5 years later than Nantong. The annual average minimum temperature of Turpan increased as same as Nantong in 1986, but the curve showed different process completely. The abrupt change year of average temperature between Turpan and Nantong were same in 1996, and the abrupt change year of average maximum temperature of Turpan was 5 years later than Nantong. For precipitation, Turpan and Nantong had the same trend of increased and decreased. The reason of almost identical trend of temperature and precipitation between Turpan and Nantong may be urbanization and population increasing influencing climate change in a small area.
文摘Climate change in the Middle East area including Jordan has started to be reflected in decreasing precipitation and increasing temperatures with their impacts on the availability of surface and groundwater. This article aims to evaluate the impacts of decreasing or increasing precipitation by 10% and 20% on the quantities of flood runoff based on recorded precipitation and runoffs of catchments during the past 60 to 70 years of observation, during which the precipitation in individual or a few years increased or decreased by tens of percentages relative to the long-term average precipitation. The results of quantification show that in Jordan as a whole, decreasing precipitation by 10% and 20% has historically (during the recording period) resulted in reductions in flood flows by 26.2% and 52.8% and that increasing precipitation by 10% and 20% has resulted in increases in flood flows by 26.4% and 56.5% respectively. These results look somehow paradox, because the general perception is that flood runoff changes in the same percentage like precipitation although flood flow is not linearly correlated with precipitation but exponentially. Decreasing precipitation in the water-scarce stressed country, Jordan due to climatic changes, will have strong implications on rain-fed and irrigated agriculture and on household water supplies with very severe socio-economic percussions expressed in increasing unemployment and poverty which may lead to social and political unrest. Therefore, proactive measures have to be implemented before disasters hit. Such measures are limited in Jordan to seawater desalination, intensified water harvesting and improved water use efficiency in agriculture.
基金Supported by Agriculture Research and Achievement Industrialization Project from Department of Science and Technology of Liaoning Province(2014210003)Special Project for Scientific Research on Social Development Program in Fuxin City,Liaoning Province(20151305)。
文摘Based on the observation data of the average temperature and precipitation of 8 national meteorological stations in the northwest region of Liaoning Province from April to October during 1961-2015,methods such as linear trend estimation,moving average,standard deviation and Mann-Kendall test are used to analyze the characteristics of average temperature and precipitation during the crop growing season in northwestern Liaoning.The results show that the average temperature during the crop growing season in the study area showed an upward trend,and the climate tendency rate was 0.193 ℃/10 a( P < 0.01).The largest contribution rate to temperature increase was in September,with a climate tendency rate of 0.27 ℃/10 a;the smallest contribution rate to the temperature increase was in July,with a climate tendency rate of 0.10 ℃/10 a.The warming trend was the most obvious in the second base year,with a climate tendency rate of 0.413 ℃/10 a( P < 0.01).The temperature was the lowest in the 1970s and the highest in the 2010s.The warming trend changed suddenly in 1996,and the sudden change reached a significant level of α = 0.05 after 2002.Precipitation was generally decreased,and the climate tendency rate was -7.68 mm/10 a.The decrease in precipitation was the most in July,and the climate tendency rate was -12.08 mm/10 a.The average temperature in the four base years failed to pass the correlation significance test.Among them,it showed an increasing trend in the second and third base year and a decreasing trend in the first and fourth base year.Rainfall was the highest in the 1960s and the lowest in the 1980s.After the abrupt change in 2002,precipitation decreased significantly.The research results provide reference for effective utilization of climate resources,rational adjustment of agricultural planting structure,and improvement of ecological environment quality.
文摘Climate change means water change, and the impacts of climate change cause not only global sea levels to rise, but also elicit dangerous levels of coastal and mainland flooding. This study relates the effects of climate-change-induced sea level risings to several harmful, and sometimes preventable, factors causing floods. One topic discussed here will be the ocean’s current (more specifically, “The Atlantic Meridional Overturning Current”) as it continues to warm with increasing temperatures. In addition to discussing the effects of the AMOC, it also relates the increasing causes that are contributing to flooding, plus the proliferation of melt from ice sheets, ice caps, and glaciers, which inevitably contributes to the devastating effects of flooding on coastal communities, destroying habitats and contributing to the extinction of both aquatic and land animals, and even impacting human infrastructure and livelihoods. This examination additionally presents the serious implications that climate change and flooding have had on the planet’s freshwater resources and reserves, which are being further destroyed by the added influx of salt water, causing water to then be treated with aquifers, an energy-intensive and highly expensive process. Lastly, this paper provides several suggested possibilities for curbing some of the harmful effects humans have already had on contributing to climate change, as well as the environmental factors that have further caused dangerous levels of flooding.
基金supported by the National Natural Science Foundation of China(40971050,40830743 and 40671045)the Knowledge Innovation Program of the Chinese Academy of Sciences(KZCX2-YW-145,317)the National Basic Research Program of China(2005CB422004)
文摘This paper describes 2007/2008 inter-annual changes in runoff from the Zhadang Glacier located on the northern slope of Nyainqêntanglha Range,Tibet,and analyzes their causes.Precipitation increased by 17.9%in summer months of 2008 compared with the same period in 2007,drainage basin runoff decreased by 33.3%,and glacial meltwater decreased by 53.8%.Change in positive accumulated air temperature explained approximately half of the inter-annual difference in glacial meltwater using a degree-day model.This suggests that the glacier is extremely sensitive to changes in air temperature.Energy balance analysis showed that change in glacier surface albedo,considered to be caused by difference in precipitation form,resulted in the large inter-annual difference in glacial meltwater.It was shown statistically that precipitation form in the summer months of 2007 was mainly rainfall which comprised 71.5%of total precipitation,while during the same period in 2008 rainfall accounted for 30.7%,with the majority of precipitation falling as snow.Precipitation form should be considered an independent factor when analyzing glacier sensitivity to climate change or forecasting the runoff from certain glaciers.
基金support by the Deutsche Forschungsgemeinschaft DFG(BR2238/23-1)。
文摘The effects of land use and land cover(LULC)on groundwater recharge and surface runoff and how these are affected by LULC changes are of interest for sustainable water resources management.However,there is limited quantitative evidence on how changes to LULC in semi-arid tropical and subtropical regions affect the subsurface components of the hydrologic cycle,particularly groundwater recharge.Effective water resource management in these regions requires conclusive evidence and understanding of the effects of LULC changes on groundwater recharge and surface runoff.We reviewed a total of 27 studies(2 modeling and 25 experimental),which reported on pre-and post land use change groundwater recharge or surface runoff magnitude,and thus allowed to quantify the response of groundwater recharge rates and runoff to LULC.Comparisons between initial and subsequent LULC indicate that forests have lower groundwater recharge rates and runoff than the other investigated land uses in semi-arid tropical/subtropical regions.Restoration of bare land induces a decrease in groundwater recharge from 42% of precipitation to between 6 and 12% depending on the final LULC.If forests are cleared for rangelands,groundwater recharge increases by 7.8±12.6%,while conversion to cropland or grassland results in increases of 3.4±2.5 and 4.4±3.3%,respectively.Rehabilitation of bare land to cropland results in surface runoff reductions of between 5.2 and 7.3%.The conversion of forest vegetation to managed LULC shows an increase in surface runoff from 1 to 14.1% depending on the final LULC.Surface runoff was reduced from 2.5 to 1.1% when grassland is converted to forest vegetation.While there is general consistency in the results from the selected case studies,we conclude that there are few experimental studies that have been conducted in tropical and subtropical semi-arid regions,despite that many people rely heavily on groundwater for their livelihoods.Therefore,there is an urgent need to increase the body of quantitative evidence given the pressure of growing human population and climate change on water resources in the region.
文摘The global distributions of the rate of precipitation change at seasonal, interannual and interdecadal scales are computed from the observed global data sets. The analysis has revealed that the monsoon regions in Asia and West Africa, and to lesser extent Australia, have the highest rate of precipitation change at all time scales in the world. These changes are manifested as seasonal jump, high interannual and interdecadal variability and abrupt changes between climate regimes.
基金National Basic Research Program of China,No.2010CB428404
文摘The runoff of some rivers in the world especially in the arid and semi-arid areas has decreased remarkably with global or regional climate change and enhanced human activities. The runoff decrease in the arid and semi-arid areas of northern China has brought severe problems in livelihoods and ecology. To reveal the variation characteristics, trends of runoff and their influencing factors have been important scientific issues for drainage basin man- agement. The objective of this study was to analyze the variation trends of the runoff and quantitatively assess the contributions of precipitation and human activities to the runoff change in the Huangfuchuan River Basin based on the measured data in 1960-2008. Two inflection points (turning years) of 1979 and 1998 for the accumulative runoff change, and one inflection point of 1979 for the accumulative precipitation change were identified using the methods of accumulative anomaly analysis. The linear relationships between year and ac- cumulative runoff in 1960-1979, 1980-1997 and 1998-2008 and between year and accu- mulative precipitation in 1960-1979 and 1980-2008 were fitted. A new method of slope change ratio of accumulative quantity (SCRAQ) was put forward and used in this study to calculate the contributions of different factors to the runoff change. Taking 1960-1979 as the base period, the contribution rate of the precipitation and human activities to the decreased runoff was 36.43% and 63.57% in 1980-1997, and 16.81% and 83.19% in 1998-2008, re- spectively. The results will play an important role in the drainage basin management. More- over, the new method of SCRAQ can be applied in the quantitative evaluation of runoff change and impacts by different factors in the river basin of arid and semi-arid areas.
基金supported by National Basic Research Program of China(Grant No. 2010CB951404)National Natural Science Foundation of China (Grant Nos. 41030527 and 41130368)Hundred Talents Program of Chinese Academy of Sciences
文摘Runoffs in the Yellow River and Yangtze River basins,China,have been changing constantly during the last half century.In this paper,data from eight river gauging stations and 529 meteorological stations,inside and adjacent to the study basins,were analyzed and compared to quantify the hydrological processes involved,and to evaluate the role of human activities in changing river discharges.The Inverse Distance Weighted(IDW)interpolation method was used to obtain climatic data coverage from station observations.According to the runoff coefficient equation,the effect of human activities and climate can be expressed by changes in runoff coefficients and changes in precipitation,respectively.Annual runoff coefficients were calculated for the period 1950-2008,according to the correlation between respective hydrological series and regional precipitation.Annual precipitation showed no obvious trend in the upper reaches of the Yellow River but a marked downward trend in the middle and downstream reaches,with declines of 8.8 and 9.8 mm/10 a,respectively.All annual runoff series for the Yellow River basin showed a significant downward trend.Runoff declined by about 7.8 mm/10 a at Sanmenxia and 10.8 mm/10 a at Lijin.The series results indicated that an abrupt change occurred in the late 1980s to early 1990s.The trend of correlations between annual runoff and precipitation decreased significantly at the Yellow River stations,with rates ranging from 0.013/10 a to 0.019/10 a.For the hydrologic series,all precipitation series showed a downward trend in the Yangtze River basin with declines ranging from about 24.7 mm/10 a at Cuntan to 18.2 mm/10 a at Datong.Annual runoff series for the upper reaches of the Yangtze River decreased significantly,at rates ranging from 9.9 to 7.2 mm/10 a.In the middle and lower reaches,the runoff series showed no significant trend,with rates of change ranging from 2.1 to 2.9 mm/10 a.Human activities had the greatest influence on changes in the hydrological series of runoff,regardless of whether the effect was negative or positive.During 1970-2008,human activities contributed to 83% of the reduction in runoff in the Yellow River basin,and to 71% of the increase in runoff in the Yangtze River basin.Moreover,the impacts of human activities across the entire basin increased over time.In the 2000s,the impact of human activities exceeded that of climate change and was responsible for 84% of the decrease and 73% of the increase in runoff in the Yellow River and Yangtze River basins,respectively.The average annual runoff from 1980 to 2008 fell by about 97%,83%,83%,and 91%,compared with 1951-1969,at the Yellow River stations Lanzhou,Sanmenxia,Huayuankou and Lijin,respectively.Most of the reduction in runoff was caused by human activities.Changes in precipitation also caused reductions in runoff of about 3%,17%,17%,and 9% at these four stations,respectively.Falling precipitation rates were the main explanation for runoff changes at the Yangtze River stations Cuntan,Yichang,Hankou,and Datong,causing reductions in runoff of 89%,74%,43%,and 35%,respectively.Underlying surface changes caused decreases in runoff in the Yellow River basin and increases in runoff in the Yangtze River basin.Runoff decreased in arid areas as a result of increased water usage,but increased in humid and sub-humid areas as a result of land reclamation and mass urbanization leading to decreases in evaporation and infiltration.
基金supported by the National Natural Science Foundation of China(Grant Nos.U20A20317 and 51539009).
文摘Climate change and land use/cover change(LUCC)can both exert great impacts on the generation processes of precipitation and runoff.However,previous studies usually neglected considering the contribution component of future LUCC in evaluating changes in hydrological cycles.In this study,an integrated framework is developed to quantify and partition the impact of climate change and LUCC on future runoff evolution.First,a daily bias correction(DBC)method and the Cellular Automaton-Markov(CA-Markov)model are used to project future climate and LUCC scenarios,and then future runoff is simulated by the calibrated Soil and Water Assessment Tool(SWAT)model with different climate and LUCC scenarios.Finally,the uncertainty of future runoff and the contribution rate of the two driving factors are systematically quantified.The Han River basin in China was selected as a case study.Results indicate that:1)both climate change and LUCC will contribute to future runoff intensification,the variation of future runoff under combined climate and LUCC is larger than these under climate change or LUCC alone;2)the projected uncertainty of median value of multi-models under RCP4.5(RCP8.5)will reach 18.14%(20.34%),12.18%(14.71%),11.01%(13.95%),and 11.41%(14.34%)at Baihe,Ankang,Danjiangkou,and Huangzhuang stations,respectively;3)the contribution rate of climate change to runoff at Baihe,Ankang,Danjiangkou,and Huangzhuang stations under RCP4.5(RCP8.5)are 91%-98%(84%-94%),while LUCC to runoff under RCP4.5(RCP8.5)only accounts for 2%-9%(6%-16%)in the annual scale.This study may provide useful adaptive strategies for policymakers on future water resources planning and management.