The design lowest navigable water level is a primary index to the channel grade division.But differ- ent method can get different calculated result,and that even brings contradiction to decide the navigation grade.In ...The design lowest navigable water level is a primary index to the channel grade division.But differ- ent method can get different calculated result,and that even brings contradiction to decide the navigation grade.In this paper the differences between guaranteed rate method and guaranteed rate-frequency method on the fundamental concept of guaranteed rate and the calculated result are carried out.According to the theoreti- cal expression forms of the two methods,the reason leading to the difference is an...展开更多
The study of ecological water demand in rivers has been a research hotspot in recent years.In this paper,selecting the widely used research methods(Tennant method,minimum monthly flow average measurement method,monthl...The study of ecological water demand in rivers has been a research hotspot in recent years.In this paper,selecting the widely used research methods(Tennant method,minimum monthly flow average measurement method,monthly average flow guarantee rate method,monthly minimum flow method,7Q 10 improvement method),the ecological water demand of rivers in the Dongting Lake basin was studied.Combined with the hydrological characteristics of the basin water system,the calculation results by the above five methods were averaged.It was obtained that the ecological water demand of rivers in the basin from April to September and from October to next March was 3.876×10^(9) and 3.425×10^(9) m^(3),respectively.The annual ecological water demand was 7.301×10^(9) m^(3),accounting for about 11.46%of the average annual runoff in the basin.The research results can provide a basis for regional water resource utilization planning and are of great significance for maintaining the health of river ecosystems.展开更多
Aquatic ecosystems require ecological water allocation to prevent from being damaged by natural disasters and undue exploitation. This paper discusses and estimates the ecological water requirements （EWRs） of typica...Aquatic ecosystems require ecological water allocation to prevent from being damaged by natural disasters and undue exploitation. This paper discusses and estimates the ecological water requirements （EWRs） of typical areas in the Huaihe Basin to determine rational allocations of water resources and pro- mote regional improvements of the ecological environment. The main river course, including Hongze Lake and Nansi Lake, was selected as the study subject. Calculational methods for the river and lake EWRs were based on the reasonableness of the results and data availability. The monthly guarantee rate method was used to calculate monthly, flood period, non-flood period, and annual EWRs for the main river course and the main tributaries at two different guarantee rates. The minimum water level method was used to calculate annual EWRs for Hongze Lake and the upper and lower Nansi Lake of 1.521×10^9 m^3, 0.637×10^9 m^3, and 0.306×10^9 m^3. The results were used to evaluate the rationality of the quantity of water resources allocated to ecological uses in the Huaihe Basin during 1998-2003. The result shows that the present water resource allocations in the Huaihe Basin cannot satisfy the basic ecological requirements for some years, especially years with less precipitation.展开更多
基金Supported by the National Key Basic Resarch and Development Plan (Grant 2003CB415200)
文摘The design lowest navigable water level is a primary index to the channel grade division.But differ- ent method can get different calculated result,and that even brings contradiction to decide the navigation grade.In this paper the differences between guaranteed rate method and guaranteed rate-frequency method on the fundamental concept of guaranteed rate and the calculated result are carried out.According to the theoreti- cal expression forms of the two methods,the reason leading to the difference is an...
文摘The study of ecological water demand in rivers has been a research hotspot in recent years.In this paper,selecting the widely used research methods(Tennant method,minimum monthly flow average measurement method,monthly average flow guarantee rate method,monthly minimum flow method,7Q 10 improvement method),the ecological water demand of rivers in the Dongting Lake basin was studied.Combined with the hydrological characteristics of the basin water system,the calculation results by the above five methods were averaged.It was obtained that the ecological water demand of rivers in the basin from April to September and from October to next March was 3.876×10^(9) and 3.425×10^(9) m^(3),respectively.The annual ecological water demand was 7.301×10^(9) m^(3),accounting for about 11.46%of the average annual runoff in the basin.The research results can provide a basis for regional water resource utilization planning and are of great significance for maintaining the health of river ecosystems.
基金the National Key Basic Research and Development (973) Program of China (No. 2006CB403407)
文摘Aquatic ecosystems require ecological water allocation to prevent from being damaged by natural disasters and undue exploitation. This paper discusses and estimates the ecological water requirements （EWRs） of typical areas in the Huaihe Basin to determine rational allocations of water resources and pro- mote regional improvements of the ecological environment. The main river course, including Hongze Lake and Nansi Lake, was selected as the study subject. Calculational methods for the river and lake EWRs were based on the reasonableness of the results and data availability. The monthly guarantee rate method was used to calculate monthly, flood period, non-flood period, and annual EWRs for the main river course and the main tributaries at two different guarantee rates. The minimum water level method was used to calculate annual EWRs for Hongze Lake and the upper and lower Nansi Lake of 1.521×10^9 m^3, 0.637×10^9 m^3, and 0.306×10^9 m^3. The results were used to evaluate the rationality of the quantity of water resources allocated to ecological uses in the Huaihe Basin during 1998-2003. The result shows that the present water resource allocations in the Huaihe Basin cannot satisfy the basic ecological requirements for some years, especially years with less precipitation.
