Maintenance of the ecosystem health of a river is of great importance for local sustainable development. On the basis of both qualitative and quantitative analysis of the influence of natural variations and human acti...Maintenance of the ecosystem health of a river is of great importance for local sustainable development. On the basis of both qualitative and quantitative analysis of the influence of natural variations and human activities on the ecosystem function of the Weihe River, the changes in major factors affecting its ecosystem health are deter- mined, which include： 1） Deficiency of environment flow： since the 1960s, the incoming stream flow shows an obvious decreasing tendency. Even in the low flow period, 80% of the water in the stream is impounded by dams for agriculture irrigation in the Baoji district. As a result, the water flow maintained in the stream for environmental use is very limited. 2） Deterioration of water quality： the concentrations of typical pollutants like Chemical Oxygen Demand （COD） and NH3-N are higher than their maximum values of the Chinese environmental quality standard. Very few fish species can survive in the River. 3） Deformation of water channels： the continuous channel sedimentation has resulted in the decrease in stream gradient, shrinkage of riverbed and the decline in the capability for flood discharge. 4） Loss of riparian vegetation： most riparian land has been occupied by urban construction activities, which have caused the loss of riparian vegetation and biodiversity and further weakened flood control and water purification functions.展开更多
[ Objective] The study aimed to analyze the changing trends of surface water quality and their causes of Weihe River in Shaanxi Province over past ten years. [ Method] Based on the available monitoring data of water q...[ Objective] The study aimed to analyze the changing trends of surface water quality and their causes of Weihe River in Shaanxi Province over past ten years. [ Method] Based on the available monitoring data of water quality of Weihe River in Shaanxi Province from 2001 to 2010, the changing trends of surface water quality of Weihe River in Shaanxi Province during recent ten years were assessed by using the assessment method of surface water quality according to the Assessment Method of Surface Water Quality and Environmental Quality Standards for Surface Water （GB 3838-2002）. Moreover, the possible reasons for the trends were also proposed. [ Result] From 2001 to 2010, there was a relatively decrea- sing trend of water pollution in Weihe River due to the considerable decline in the content of the main environmental pollutants like permanganate in- dex, 5-day biochemical oxygen demand （ BOD5 ）, ammonia nitrogen, oil and volatile phenol. Meanwhile, the comprehensive pollution index fell by 62.7%, eliminating Weihe River＇s black and stink on schedule. However, the overall surface water quality of Weihe River was still polluted heavily in each year, and the pollution control of Xi＇an section should be paid more attention to. [ Conclusion] The research could provide scientific refer- ences for the comprehensive environmental control of Weihe River in Shaanxi Province.展开更多
Palaeoflood hydrological study is a frontal subject of global change study. Using sedimentology, geomorphology and OSL dating methods, the typical palaeoflood slackwater deposits were studied in the Qishuihe River val...Palaeoflood hydrological study is a frontal subject of global change study. Using sedimentology, geomorphology and OSL dating methods, the typical palaeoflood slackwater deposits were studied in the Qishuihe River valley. The results showed that five flooding episodes with 21 palaeoflood events occurred during 4300-4250 a B.P., 4250-4190 a B.P., 4190-4100 a B.P., 4100-4000 a B.P. and 3100-3010 a B.P., respectively, during the Holocene period. The palaeoflood peak discharges were calculated with hydrological models. With a combination of the gauged flood, historical flood and palaeoflood hydrological data, the archives of flood events were extended to over 10,000 years in the Qishuihe River valley, and the flood frequency-peak discharge relationship curve was established accurately. These research results played important roles in mitigating flood hazard, hydraulic engineering and also the development of water resources in the semiarid Weihe River basin.展开更多
基金Acknowledgements This study is jointly supported by the National Natural Science Foundation of China （Grant Nos. 51079123 and 51379175）, Program for New Century Excellent Talents in University （No. NCET-11-1045）, Technology Foundation for Selected Overseas Chinese Scholar （2011 -12-09）, Scientific Research Foundation for Returned Scholars （2010-1174）, and Natural Science Foundation of Shaanxi Province （Grant No.12k798）.
文摘Maintenance of the ecosystem health of a river is of great importance for local sustainable development. On the basis of both qualitative and quantitative analysis of the influence of natural variations and human activities on the ecosystem function of the Weihe River, the changes in major factors affecting its ecosystem health are deter- mined, which include： 1） Deficiency of environment flow： since the 1960s, the incoming stream flow shows an obvious decreasing tendency. Even in the low flow period, 80% of the water in the stream is impounded by dams for agriculture irrigation in the Baoji district. As a result, the water flow maintained in the stream for environmental use is very limited. 2） Deterioration of water quality： the concentrations of typical pollutants like Chemical Oxygen Demand （COD） and NH3-N are higher than their maximum values of the Chinese environmental quality standard. Very few fish species can survive in the River. 3） Deformation of water channels： the continuous channel sedimentation has resulted in the decrease in stream gradient, shrinkage of riverbed and the decline in the capability for flood discharge. 4） Loss of riparian vegetation： most riparian land has been occupied by urban construction activities, which have caused the loss of riparian vegetation and biodiversity and further weakened flood control and water purification functions.
文摘[ Objective] The study aimed to analyze the changing trends of surface water quality and their causes of Weihe River in Shaanxi Province over past ten years. [ Method] Based on the available monitoring data of water quality of Weihe River in Shaanxi Province from 2001 to 2010, the changing trends of surface water quality of Weihe River in Shaanxi Province during recent ten years were assessed by using the assessment method of surface water quality according to the Assessment Method of Surface Water Quality and Environmental Quality Standards for Surface Water （GB 3838-2002）. Moreover, the possible reasons for the trends were also proposed. [ Result] From 2001 to 2010, there was a relatively decrea- sing trend of water pollution in Weihe River due to the considerable decline in the content of the main environmental pollutants like permanganate in- dex, 5-day biochemical oxygen demand （ BOD5 ）, ammonia nitrogen, oil and volatile phenol. Meanwhile, the comprehensive pollution index fell by 62.7%, eliminating Weihe River＇s black and stink on schedule. However, the overall surface water quality of Weihe River was still polluted heavily in each year, and the pollution control of Xi＇an section should be paid more attention to. [ Conclusion] The research could provide scientific refer- ences for the comprehensive environmental control of Weihe River in Shaanxi Province.
基金National Natural Science Foundation of China, No.40771018Natural Science Foundation of Shaanxi Prov-ince, No.2006D01Basic Research Fund of Shaanxi Normal University, No.200702001
文摘Palaeoflood hydrological study is a frontal subject of global change study. Using sedimentology, geomorphology and OSL dating methods, the typical palaeoflood slackwater deposits were studied in the Qishuihe River valley. The results showed that five flooding episodes with 21 palaeoflood events occurred during 4300-4250 a B.P., 4250-4190 a B.P., 4190-4100 a B.P., 4100-4000 a B.P. and 3100-3010 a B.P., respectively, during the Holocene period. The palaeoflood peak discharges were calculated with hydrological models. With a combination of the gauged flood, historical flood and palaeoflood hydrological data, the archives of flood events were extended to over 10,000 years in the Qishuihe River valley, and the flood frequency-peak discharge relationship curve was established accurately. These research results played important roles in mitigating flood hazard, hydraulic engineering and also the development of water resources in the semiarid Weihe River basin.
