| Inter basin water transfer(IBWT)project is an important measure to realize the spatial balance of water resources to divert water resources from the water-rich area to the water-deficient area.Due to the extremely uneven spatial and temporal distribution of water resources,in recent years,the number,scale,topological structure and function orientation of IBWT projects of various grades in China are increasing day by day.As a result,there are many complex and urgent key problems in the IBWT system,which bring great challenges to the rational and efficient operation of the IBWT system.In this context,it is necessary to focus on the analysis of the key problems in this complex IBWT system,to study the key theories,and to put forward the practical key technologies.In this study,three key issues,namely,the closed management model of water resources,the new dual IBWT(DIBWT)operation mode,and the drought emergency operation on the complex IBWT system in the Han River to Wei River IBWT(HW-IBWT)and the Jialing across Han River to Wei River IBWT(JHW-DIBWT),which are both in Shaanxi Province as the research examples,through the key theory and key technology research project example application is realized.Firstly,the characteristics of runoff in each basin involved in the study area,as well as the drought situation are expounded;On this basis,aiming at the closed management on the IBWT water resources in the whole process from source to user,a closed management model of IBWT water resources is established to determine the integrated management model of diversion-supply-allocation;Secondly,DIBWT system characterized by"subsequent water source project" is firstly defined theoretically,and the DIBWT operation mode with multi-objective is studied;Finally,the drought emergency operation rules for the HW-IBWT is proposed,which is composed of stage drought operation zone and the quantifiable water supply hedging coefficient,in addation,the application effect of drought emergency operation for the HW-IBWT is demonstrated.Main conclusions are drawn as follows:(1)The dynamic sequence of reservoirs transfer in the transfer area is proposed and compared with the fixed sequence transfer schemes.The results show that adopting the dynamic index of reservoir transfer order RTO,the combined water transfer of the HW-IBWT Project can meet the total transfer target of 1.5 billion m~3,and the water abandoning is the least,which can give full play to the complementary performance of abundant runoff of Huangjinxia Reservoir and strong regulation ability of Sanhekou Reservoir to achieve the transfer trade-off between the two reservoirs.In addition,the comparison of multiple schemes also shows that the sequence of reservoirs transfer has a great influence on the operation mode and the overall transfer efficiency of the IBWT system.(2)The topological structure and functional composition of each water source of the HW-IBWT Project are generalized and analyzed.A hierarchical planning method(HPM)for IBWT water resource management with built-in modules of water transfer,water supply and water allocation is constructed.Then,a flowchart with mutual feedback mechanism is adopted to decompose the model and establish the relationship among the three modules;the HW-IBWT instance running results show that the water diversion and water supply process appear obvious phenomenon of "mirror",and the allocation can meet the different regions and objects with the planned guarantee rate and shortage rate,which reveals integrated diversion-supply-allocation coupling relation,as well as the reality from the water source to user closed water resources management process.(3)The concept and connotation of the dual interbasin water transfer(DIBWT)system,which is mainly characterized by "subsequent water source project",is firstly proposed in theory.A DIBWT model with multiple objectives,such as increasing the transfer water,stabilizing the fluctuation of transfer process,and supplementing the ecological water,is established,and the model is solved by simulation-optimization approach;the results reveal that the original transfer area(OTA)in the DIBWT system has dual roles and functions.The rationality and effectiveness of the established model and operation rules are illustrated by the water-supply,water-transfer and water-receipt rule curves,which can direct the integrated water resource transfer from the OTA and the additional transfer area(ATA)to a corporate intake area(CIA).(4)Comparing with the evaluation after simulated operation of typical IBWT projects,the comparative results show that for relatively uniform water transfer demand,the total amount of water transferred from JHW-DIBWT Project is 1.518 billion m~3(guarantee rate 98.0%),which is higher than the amount of HW-IBWT Project 1.419 billion m~3(guarantee rate 87.6%);in a typical dry year(natural runoff frequency 95%),HW-IBWT Project could not reach the minimum monthly water transfer limit line 70%,while JHW-DIBWT Project could reach not only water transfer target line in five months,but also the water transfer limit line in seven months,showing the ability of JHW-DIBWT Project to regulate drought conditions;in different time scales(ten days,month,year),the water transfer process from JHW-DIBWT Project is more stable than that of HW-IBWT Project,and the transfer fluctuation is greatly reduced;the ecological guarantee rate increased to 96.4%and 98.2%,compared with 66.1%and 83.9%,respectively,after the water transfer from JHW-DIBWT Project to the upstream and downstream ecologically sensitive sections.(5)The drought operation zone(DOZ)of the reservoir is proposed,which is formed by the closure of early warning water level(EWWL)and drought limited water level(DLWL).Combined with the quantifiable water supply hedging coefficient,the emergency operation rules in drought time for the HW-IBWT are formulated,which have the following rules:In response to the same drought and in the same stage,water supply hedging coefficient of Sanhekou Reservoir is greater than that of Jinpen Reservoir,which indicates that Sanhekou Reservoir has a greater transfer ratio and a stronger ability of drought control;In response to different drought types,water supply hedging coefficient of these reservoirs increased when both two areas drought compared with any single drought,indicating that the reservoirs should increase the amount of water transfer(supply)with the drought aggravation;Among different stages,water supply hedging coefficient of stage iii is significantly higher than stage i and ii,which is the key drought emergency operation period for natural runoff from abundant to dry and beneficial to ensuring the drought emergency operation efficiency.(6)Comparative analysis between the drought emergency operation and conventional operation of HW-IBWT Project:when the water transfer area or the water intake area is in drought alone,the total water supply in HW-IBWT drought emergency operation is lower than that of conventional operation,indicating that the total drought emergency water is slightly reduced under the influence of "hedge" by the quantitative water supply hedging coefficient;In response to both two areas drought,the HW-IBWT Project transfer water and local supply water are larger than the conventional operation results,and the total drought emergency water is 1.563 billion m~3,greater than that of conventional operation 1.556 billion m~3,indicating that the more severe the drought,the higher the efficiency of drought emergency operation;In addition,the water supply degree of drought emergency operation can meet 70%requirements.Compared with conventional operation,it is within a small range and the water supply process is relatively concentrated. |
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