A large sand bar develops in the inner Qiantang River Estuary,China.It is a unique sedimentary system,elongating landwards by about 130 km.Based on long-term series of bathymetric data in each April,July,and November ...A large sand bar develops in the inner Qiantang River Estuary,China.It is a unique sedimentary system,elongating landwards by about 130 km.Based on long-term series of bathymetric data in each April,July,and November since the 1960s,this study investigated the morphological behavior of this bar under natural conditions and the influence of a large-scale river narrowing project(LRNP)implemented in the last decades.The results show that three timescales,namely the seasonal,interannual and decadal timescales,can be distinguished for the sand bar evolution.The first two are related to the seasonal and interannual variations of river discharge.During high discharge seasons or years,erosion took place at the upper reach and sedimentation at the lower reach.Consequently,the bar apex shifted seaward.The opposite development took place during low discharge seasons or years.The decadal timescale is related to LRNP.Due to the implementation of LRNP,the upper reach has experienced apparent erosion and currently a new equilibrium state has been reached;whereas the lower reach has been accumulated seriously and the accumulation still continues.Nonlinear relationships for how the bar apex location and elevation depend on the river discharge over various stages of LRNP have been established.Compared with the earlier stage of LRNP,the bar apex at present has shifted seaward by about 12 km and lowered by about 1 m.The sand bar movement has significant feedback on the hydrographic conditions along the estuary and has practical implications for coastal management.展开更多
Zarrineh River is located in the northwest of Iran,providing more than 40%of the total inflow into the Lake Urmia that is one of the largest saltwater lakes on the earth.Lake Urmia is a highly endangered ecosystem on ...Zarrineh River is located in the northwest of Iran,providing more than 40%of the total inflow into the Lake Urmia that is one of the largest saltwater lakes on the earth.Lake Urmia is a highly endangered ecosystem on the brink of desiccation.This paper studied the impacts of climate change on the streamflow of Zarrineh River.The streamflow was simulated and projected for the period 1992-2050 through seven CMIP5(coupled model intercomparison project phase 5)data series(namely,BCC-CSM1-1,BNU-ESM,CSIRO-Mk3-6-0,GFDL-ESM2G,IPSL-CM5A-LR,MIROC-ESM and MIROC-ESM-CHEM)under RCP2.6(RCP,representative concentration pathways)and RCP8.5.The model data series were statistically downscaled and bias corrected using an artificial neural network(ANN)technique and a Gamma based quantile mapping bias correction method.The best model(CSIRO-Mk3-6-0)was chosen by the TOPSIS(technique for order of preference by similarity to ideal solution)method from seven CMIP5 models based on statistical indices.For simulation of streamflow,a rainfall-runoff model,the hydrologiska byrans vattenavdelning(HBV-Light)model,was utilized.Results on hydro-climatological changes in Zarrineh River basin showed that the mean daily precipitation is expected to decrease from 0.94 and 0.96 mm in 2015 to 0.65 and 0.68 mm in 2050 under RCP2.6 and RCP8.5,respectively.In the case of temperature,the numbers change from 12.33℃ and 12.37℃ in 2015 to 14.28℃ and 14.32℃ in 2050.Corresponding to these climate scenarios,this study projected a decrease of the annual streamflow of Zarrineh River by half from 2015 to 2050 as the results of climatic changes will lead to a decrease in the annual streamflow of Zarrineh River from 59.49 m^(3)/s in 2015 to 22.61 and 23.19 m^(3)/s in 2050.The finding is of important meaning for water resources planning purposes,management programs and strategies of the Lake's endangered ecosystem.展开更多
The Yangtze River has nurtured the fertile land on both its banks and hundreds of millions of Chinese people. but its raging waters have also wreaked havoc on the people living in its reaches. Since the founding of Ne...The Yangtze River has nurtured the fertile land on both its banks and hundreds of millions of Chinese people. but its raging waters have also wreaked havoc on the people living in its reaches. Since the founding of New China, large-scale surveys, planning, scientific research and feasibility studies have been carried out in an effort to harness the展开更多
基金The National Natural Science Foundation of China under contract Nos 41676085 and 42176170the Zhejiang Provincial Hydraulic Science and Technology Planning Project under contract No.RB2033the Zhejiang Provincial Natural Science Foundation of China under contract No.LY16D060004.
文摘A large sand bar develops in the inner Qiantang River Estuary,China.It is a unique sedimentary system,elongating landwards by about 130 km.Based on long-term series of bathymetric data in each April,July,and November since the 1960s,this study investigated the morphological behavior of this bar under natural conditions and the influence of a large-scale river narrowing project(LRNP)implemented in the last decades.The results show that three timescales,namely the seasonal,interannual and decadal timescales,can be distinguished for the sand bar evolution.The first two are related to the seasonal and interannual variations of river discharge.During high discharge seasons or years,erosion took place at the upper reach and sedimentation at the lower reach.Consequently,the bar apex shifted seaward.The opposite development took place during low discharge seasons or years.The decadal timescale is related to LRNP.Due to the implementation of LRNP,the upper reach has experienced apparent erosion and currently a new equilibrium state has been reached;whereas the lower reach has been accumulated seriously and the accumulation still continues.Nonlinear relationships for how the bar apex location and elevation depend on the river discharge over various stages of LRNP have been established.Compared with the earlier stage of LRNP,the bar apex at present has shifted seaward by about 12 km and lowered by about 1 m.The sand bar movement has significant feedback on the hydrographic conditions along the estuary and has practical implications for coastal management.
文摘Zarrineh River is located in the northwest of Iran,providing more than 40%of the total inflow into the Lake Urmia that is one of the largest saltwater lakes on the earth.Lake Urmia is a highly endangered ecosystem on the brink of desiccation.This paper studied the impacts of climate change on the streamflow of Zarrineh River.The streamflow was simulated and projected for the period 1992-2050 through seven CMIP5(coupled model intercomparison project phase 5)data series(namely,BCC-CSM1-1,BNU-ESM,CSIRO-Mk3-6-0,GFDL-ESM2G,IPSL-CM5A-LR,MIROC-ESM and MIROC-ESM-CHEM)under RCP2.6(RCP,representative concentration pathways)and RCP8.5.The model data series were statistically downscaled and bias corrected using an artificial neural network(ANN)technique and a Gamma based quantile mapping bias correction method.The best model(CSIRO-Mk3-6-0)was chosen by the TOPSIS(technique for order of preference by similarity to ideal solution)method from seven CMIP5 models based on statistical indices.For simulation of streamflow,a rainfall-runoff model,the hydrologiska byrans vattenavdelning(HBV-Light)model,was utilized.Results on hydro-climatological changes in Zarrineh River basin showed that the mean daily precipitation is expected to decrease from 0.94 and 0.96 mm in 2015 to 0.65 and 0.68 mm in 2050 under RCP2.6 and RCP8.5,respectively.In the case of temperature,the numbers change from 12.33℃ and 12.37℃ in 2015 to 14.28℃ and 14.32℃ in 2050.Corresponding to these climate scenarios,this study projected a decrease of the annual streamflow of Zarrineh River by half from 2015 to 2050 as the results of climatic changes will lead to a decrease in the annual streamflow of Zarrineh River from 59.49 m^(3)/s in 2015 to 22.61 and 23.19 m^(3)/s in 2050.The finding is of important meaning for water resources planning purposes,management programs and strategies of the Lake's endangered ecosystem.
文摘The Yangtze River has nurtured the fertile land on both its banks and hundreds of millions of Chinese people. but its raging waters have also wreaked havoc on the people living in its reaches. Since the founding of New China, large-scale surveys, planning, scientific research and feasibility studies have been carried out in an effort to harness the
