The ecological water demand (EWD) is the least water amount required to maintain the structure and the function of the special eco-system and the temporal scale of a study on the EWD must be a season's time. Based...The ecological water demand (EWD) is the least water amount required to maintain the structure and the function of the special eco-system and the temporal scale of a study on the EWD must be a season's time. Based on GIS and RS with the source information of hydrological data of 46 hydrological gauges covering 52 years and the digital images of Landsat TM in 1986, 1996 and 2000, the landscape patterns, precipitation and runoff in the East Liaohe River Basin were analyzed. With the result of the above analysis, the spatial and temporal changes of the ecological water demand in the slope systems (EWDSS) of the East Liaohe River Basin (ELRB) were derived. Landscapes in the ELRB are dispersed and strongly disturbed by human actions. The hydrological regime in ELRB has distinct spatial variations. The average annual EWDSS in the ELRB is 504.72 mm (324.08-618.89 mm), and the average EWDSS in the growth season (from May to September) is 88.29% of the year's total EWDSS .The ultimate guaranteeing ratio of the EWDSS in ELRB is 90%. The scarce EWDSS area in the whole year and in the growth season are 60.47% and 74.01% of the entire basin respectively. The trend of scarce EWDSS area is most serious according to the quantity and area of scarce EWDSS regions.展开更多
We demonstrate that there is significant skill in the GloSea5 operational seasonal forecasting system for predicting June mean rainfall in the middle/lower Yangtze River basin up to four months in advance.Much of the ...We demonstrate that there is significant skill in the GloSea5 operational seasonal forecasting system for predicting June mean rainfall in the middle/lower Yangtze River basin up to four months in advance.Much of the rainfall in this region during June is contributed by the mei-yu rain band.We find that similar skill exists for predicting the East Asian summer monsoon index(EASMI)on monthly time scales,and that the latter could be used as a proxy to predict the regional rainfall.However,there appears to be little to be gained from using the predicted EASMI as a proxy for regional rainfall on monthly time scales compared with predicting the rainfall directly.Although interannual variability of the June mean rainfall is affected by synoptic and intraseasonal variations,which may be inherently unpredictable on the seasonal forecasting time scale,the major influence of equatorial Pacific sea surface temperatures from the preceding winter on the June mean rainfall is captured by the model through their influence on the western North Pacific subtropical high.The ability to predict the June mean rainfall in the middle and lower Yangtze River basin at a lead time of up to 4 months suggests the potential for providing early information to contingency planners on the availability of water during the summer season.展开更多
Topographic map evidence from the Wyoming Wind River-Sweetwater River drainage divide area is used to test a recently proposed regional geomorphology paradigm defined by massive south- and southeast-oriented continent...Topographic map evidence from the Wyoming Wind River-Sweetwater River drainage divide area is used to test a recently proposed regional geomorphology paradigm defined by massive south- and southeast-oriented continental ice sheet melt water floods that flowed across the entire Missouri River drainage basin. The new paradigm forces recognition of an ice sheet created and occupied deep “hole” and is fundamentally different from the commonly accepted paradigm in which a pre-glacial north- and northeast-oriented slope would have prevented continental ice sheet melt water from reaching or crossing the Wind River-Sweetwater River drainage divide. Divide crossings (or low points) are identified as places where water once flowed across the drainage divide. Map evidence is interpreted first from the accepted paradigm perspective and second from the new paradigm perspective to determine the simplest explanation. Both paradigm perspectives suggest south-oriented water crossed the drainage divide, although accepted paradigm interpretations do not satisfactorily explain the large number of observed divide crossings and are complicated by the need to bury the Owl Creek and Bridger Mountains to explain why the Wind River now flows in a north direction through Wind River Canyon. New paradigm interpretations explain the large number of divide crossings as diverging and converging channel evidence (as in flood-formed anastomosing channel complexes), Owl Creek and Bridger Mountain uplift to have occurred as south-oriented floodwaters carved Wind River Canyon, and a major flood flow reversal (caused by ice sheet related crustal warping and the opening up of deep “hole” space by ice sheet melting) as being responsible for the Wind River abrupt turn to the north. While this test only addresses topographic map evidence, Occam’s Razor suggests the new paradigm offers what in science should be the preferred Wind River-Sweetwater River drainage divide origin interpretations.展开更多
Using the US Climate Prediction Center （CPC） soil moisture dataset and the observed precipitation over China together with the NCEP/NCAR reanalysis wind and air temperature, the relationship between June precipitati...Using the US Climate Prediction Center （CPC） soil moisture dataset and the observed precipitation over China together with the NCEP/NCAR reanalysis wind and air temperature, the relationship between June precipitation over mid-lower reaches of the Yangtze River basin （MLR-YRB） and spring soil moisture over the East Asian monsoon region was explored, with the signal of the ENSO effect on precipitation removed. A significant positive correlation was found between the mean June precipitation and the preceding soil moisture over the MRL-YRB. The possible response mechanism for this relationship was also investigated. It is found that when the soil over the MRL-YRB is wetter （drier） than normal in April and May, the air temperature in the lower troposphere over this region in May is lower （higher） than normal, and this temperature effect leads to a decrease （increase） in the temperature contrast between the land and the sea. Generally, a decrease （increase） in the land-sea temperature contrast leads to weaker （stronger） East Asian summer monsoon in June. Southerly （northerly） wind anomalies at 850 hPa then show up in the south of the Yangtze River basin while northerly （southerly） wind anomalies dominate in the north. These anomalies lead to the convergence （divergence） of wind and water vapor and hence gives rise to more （less） precipitation in June over the MLR-YRB.展开更多
为在径流模拟中充分考虑水库的综合调蓄作用,改善了SWAT(The Soil and Water Assessment Tool)模型的水库算法,在水库模块中增加基于水库供水发电调度规则的水库出流模拟算法,以提高径流模拟精度。选择东江流域作为典型流域,分别应用改...为在径流模拟中充分考虑水库的综合调蓄作用,改善了SWAT(The Soil and Water Assessment Tool)模型的水库算法,在水库模块中增加基于水库供水发电调度规则的水库出流模拟算法,以提高径流模拟精度。选择东江流域作为典型流域,分别应用改进前后的SWAT模型进行径流模拟,并分析模型改进的效果,结果表明:修改后的SWAT模型解决了水库模拟出流量在非汛期过低、汛期过大的问题,能更有效地模拟枯季径流和洪峰流量,明显提高了月径流及日径流的模拟精度,其中,月径流模拟中率定期内R2提高了0.06~0.22,NS提高了0.06~0.52,验证期内R2提高了0.1~0.19,NS提高了0.12~1.22;日径流模拟中率定期内R2提高了0.04~0.16,NS提高了0.04~0.46,验证期内R2提高了0.11~0.15,NS提高了0.15~1.21。展开更多
基金Key Resource and Environment Projects of CAS,No.KZ952-J1-067
文摘The ecological water demand (EWD) is the least water amount required to maintain the structure and the function of the special eco-system and the temporal scale of a study on the EWD must be a season's time. Based on GIS and RS with the source information of hydrological data of 46 hydrological gauges covering 52 years and the digital images of Landsat TM in 1986, 1996 and 2000, the landscape patterns, precipitation and runoff in the East Liaohe River Basin were analyzed. With the result of the above analysis, the spatial and temporal changes of the ecological water demand in the slope systems (EWDSS) of the East Liaohe River Basin (ELRB) were derived. Landscapes in the ELRB are dispersed and strongly disturbed by human actions. The hydrological regime in ELRB has distinct spatial variations. The average annual EWDSS in the ELRB is 504.72 mm (324.08-618.89 mm), and the average EWDSS in the growth season (from May to September) is 88.29% of the year's total EWDSS .The ultimate guaranteeing ratio of the EWDSS in ELRB is 90%. The scarce EWDSS area in the whole year and in the growth season are 60.47% and 74.01% of the entire basin respectively. The trend of scarce EWDSS area is most serious according to the quantity and area of scarce EWDSS regions.
基金supported by the UK–China ResearchInnovation Partnership Fund through the Met Office Climate Science for Service Partnership (CSSP) China as part of the Newton Fund
文摘We demonstrate that there is significant skill in the GloSea5 operational seasonal forecasting system for predicting June mean rainfall in the middle/lower Yangtze River basin up to four months in advance.Much of the rainfall in this region during June is contributed by the mei-yu rain band.We find that similar skill exists for predicting the East Asian summer monsoon index(EASMI)on monthly time scales,and that the latter could be used as a proxy to predict the regional rainfall.However,there appears to be little to be gained from using the predicted EASMI as a proxy for regional rainfall on monthly time scales compared with predicting the rainfall directly.Although interannual variability of the June mean rainfall is affected by synoptic and intraseasonal variations,which may be inherently unpredictable on the seasonal forecasting time scale,the major influence of equatorial Pacific sea surface temperatures from the preceding winter on the June mean rainfall is captured by the model through their influence on the western North Pacific subtropical high.The ability to predict the June mean rainfall in the middle and lower Yangtze River basin at a lead time of up to 4 months suggests the potential for providing early information to contingency planners on the availability of water during the summer season.
文摘Topographic map evidence from the Wyoming Wind River-Sweetwater River drainage divide area is used to test a recently proposed regional geomorphology paradigm defined by massive south- and southeast-oriented continental ice sheet melt water floods that flowed across the entire Missouri River drainage basin. The new paradigm forces recognition of an ice sheet created and occupied deep “hole” and is fundamentally different from the commonly accepted paradigm in which a pre-glacial north- and northeast-oriented slope would have prevented continental ice sheet melt water from reaching or crossing the Wind River-Sweetwater River drainage divide. Divide crossings (or low points) are identified as places where water once flowed across the drainage divide. Map evidence is interpreted first from the accepted paradigm perspective and second from the new paradigm perspective to determine the simplest explanation. Both paradigm perspectives suggest south-oriented water crossed the drainage divide, although accepted paradigm interpretations do not satisfactorily explain the large number of observed divide crossings and are complicated by the need to bury the Owl Creek and Bridger Mountains to explain why the Wind River now flows in a north direction through Wind River Canyon. New paradigm interpretations explain the large number of divide crossings as diverging and converging channel evidence (as in flood-formed anastomosing channel complexes), Owl Creek and Bridger Mountain uplift to have occurred as south-oriented floodwaters carved Wind River Canyon, and a major flood flow reversal (caused by ice sheet related crustal warping and the opening up of deep “hole” space by ice sheet melting) as being responsible for the Wind River abrupt turn to the north. While this test only addresses topographic map evidence, Occam’s Razor suggests the new paradigm offers what in science should be the preferred Wind River-Sweetwater River drainage divide origin interpretations.
基金Supported by the National Basic Research Program of China(2009CB421406)Special Public Welfare Research Fund for Meteorological Profession of China Meteorological Administration(GYHY200906016)+1 种基金National Science and Technology Support Program of China(2007BAC29B03)National Natural Science Foundation of China(40821092)
文摘Using the US Climate Prediction Center （CPC） soil moisture dataset and the observed precipitation over China together with the NCEP/NCAR reanalysis wind and air temperature, the relationship between June precipitation over mid-lower reaches of the Yangtze River basin （MLR-YRB） and spring soil moisture over the East Asian monsoon region was explored, with the signal of the ENSO effect on precipitation removed. A significant positive correlation was found between the mean June precipitation and the preceding soil moisture over the MRL-YRB. The possible response mechanism for this relationship was also investigated. It is found that when the soil over the MRL-YRB is wetter （drier） than normal in April and May, the air temperature in the lower troposphere over this region in May is lower （higher） than normal, and this temperature effect leads to a decrease （increase） in the temperature contrast between the land and the sea. Generally, a decrease （increase） in the land-sea temperature contrast leads to weaker （stronger） East Asian summer monsoon in June. Southerly （northerly） wind anomalies at 850 hPa then show up in the south of the Yangtze River basin while northerly （southerly） wind anomalies dominate in the north. These anomalies lead to the convergence （divergence） of wind and water vapor and hence gives rise to more （less） precipitation in June over the MLR-YRB.
文摘为在径流模拟中充分考虑水库的综合调蓄作用,改善了SWAT(The Soil and Water Assessment Tool)模型的水库算法,在水库模块中增加基于水库供水发电调度规则的水库出流模拟算法,以提高径流模拟精度。选择东江流域作为典型流域,分别应用改进前后的SWAT模型进行径流模拟,并分析模型改进的效果,结果表明:修改后的SWAT模型解决了水库模拟出流量在非汛期过低、汛期过大的问题,能更有效地模拟枯季径流和洪峰流量,明显提高了月径流及日径流的模拟精度,其中,月径流模拟中率定期内R2提高了0.06~0.22,NS提高了0.06~0.52,验证期内R2提高了0.1~0.19,NS提高了0.12~1.22;日径流模拟中率定期内R2提高了0.04~0.16,NS提高了0.04~0.46,验证期内R2提高了0.11~0.15,NS提高了0.15~1.21。
