| As one of the main factors that affect the safety of water resources,drought and water shortage is a chronic and frequent occurrence of natural disasters in the world,and its impact on social life and economic development is big,wide range and long duration,and its deep harm has already beyond any other natural disasters at now,It can be said that drought has become a major destabilizing factor affecting the development of the world,and the bottleneck factors affecting the sustainable development of the national economy.Unfortunately,the special geographical conditions and climatic characteristics determine that China is also a country where drought occur frequently.And now the problem of drought has become a significant problem which is affecting the sustainable development of social economy and the sustainable use and management of water resources.Especially in recent years,the frequency and degree of drought in China is increasing due to the impact of global climate change,which has been caused a seriously water shortage contradiction.Now the drought is seriously restricting the harmonious development of society economy,and affect the stability of China.And as a result,it can be seen that the impact of the current stage drought problem on China's development is much higher than any period of history.The research of drought is at an urgent point at now,the problem of drought has been a hotspot of international academic research in recent years in the word.The research mainly involves four contents such as drought law,drought index and assessment,drought warning and drought management.At present,some results of the research have been applied to the production line,and it has played a positive role in regional drought mitigation.However,due to the complexity of the drought itself,there are still many problems in the past achievements of the drought management field needed to be studied and perfected,such as the drought index system is imperfect,the basic research is lacking,heavy warning but light response,heavy emergency but light defense,the decision support system is not practical and so on.In view of this,and aiming at those shortcomings and deficiencies of the above research in the field of drought management,this paper intends to discuss the problems of mechanism and practical in the process of drought crisis assessment,early warning and resistance to drought from the perspective of regional drought resistance practice,and taking Jinghuiqu irrigation district in Shaanxi Province as an example to carry out.The specific process in this paper is as follows.Firstly,combining the multi-water resources supply mode in the irrigation district,this paper puts forward and constructs bilateral drought irrigation supply crisis diagnosis index system.Secondly,after coupling with the multi water source binary water cycle simulation model and the rolling correction model,the drought rolling crisis early warning mechanism for irrigation district has been established in this paper,which can uninterruptedly release the warning information of the drought crisis under the combining the probability of future precipitation and the changes of ground soil entropy.Thirdly,on the basis of above,this paper further establishes a “diagnosis-early warning-decision” framework system for drought resistant in irrigation district,which can realize the simulate of early warning and decisionmaking through combine with multi water source binary water cycle simulation model to At the same time,the drought crisis response plan library is constructed based on the historical drought information,which can support the whole process of from the diagnosis,early warning to the decision making.Finally,taking the Jinghuqu irrigation district as an example,this paper validates and analysis the rationality and practicability of the drought diagnosis and early warning system which is established in this study under the multi water supply mode.The main contents and conclusions are as follows:(1)Analysis on present situation and drought resistance of Jinghuiqu irrigation district.Based on the investigation of the present situation of Jinghuiqu irrigation district,this paper found that the precipitation and runoff of irrigation district are strongly changing,and the distribution is uneven during the year.At the same time,the flood and waterlogging of Jinghe River and the evaporation of irrigation district are strong.This paper also found that the water volume of Jinghui canal is reduced and the sediment concentration is large,but the water demand of irrigation district is increasing year by year.The problem of overgrowth of groundwater is becoming more and more serious.In addition,the drought is occurring frequently in Jinghuiqu irrigation district,and now the irrigation district is also facing with many else problems such as the serious shortage of water resources,the failure of the canal system,the water saving management and immature irrigation technology,over exploitation and water pollution problems coexist and so on.At present,this is facing a great pressure on drought resistance in Jinghuiqu irrigation district.(2)Drought crisis diagnosis index system in irrigation district.In this paper,a drought crisis diagnosis index system in irrigation district is proposed based on the theory of binary water cycle.The index system covers the dual characteristics of the drought status and the ability of drought resistance(water source)in irrigation district,which can answer the questions of two levels of real-time drought and water conditions in the process of drought.At the same time,in this index system,a comprehensive drought crisis diagnostic index DAI is constructed by integrating the drought status index D and the drought resistance index S.Through that system,the decision makers can real-time master the development of the drought,the change of the drought resistance ability and the crisis degree of the drought.That is,in the case of accurately reflecting the current drought situation in the irrigation district,the decision makers can further combine the future water supply and the current decision making plan to simulate the future potential threat of drought(3)The realization of multi water source binary water cycle simulation model.As a result,the drought crisis diagnosis index system although has the property of real-time acquisition,but its threshold setting and early warning mechanism are required to be supported by the binary water cycle simulation model.In this paper,on the basic of the multi water supply model of the irrigation district,the irrigation district water diversion model is established by coupling the distributed hydrological model and the water resources allocation model in the Jinghe River Basin.After combine with the soil moisture prediction model and the groundwater balance model,the multi water source binary water cycle simulation model in the irrigation district is established to ensure the realization of index acquisition,implementation of early warning and decision simulation function.The final results show that,this model not only can simulate the process of binary water cycle in the process of drought event evolution,but also it can provide support for the rational use of surface water and groundwater,exert maximum drought resistance potential and effectively reduce the risk of drought in irrigation district.(4)The rolling early warning mechanism and decision system framework of drought crisis in irrigation district.Based on the multi water source binary water cycle simulation model,the drought crisis diagnosis system of the irrigation district is integrated with the rolling early warning mechanism and the decision support mechanism in this paper,and then the “drought crisis diagnosis-early warning-decision-making” framework system is established.The results show that,under the mechanism of rolling early warning and decision making simulation,this framework system can realize the drought crisis early warning and decision making support for the whole process of "early warning-pre-decision-pre-decision effect analysis of pre-decision making-making decision-early warning" in the irrigation district.On the other hand,it also can compensate for the lack of support for the process of drought resistance through the conventional drought assessment system during the process of drought evolution.(5)Instance analysis.In this paper,on the basis of the measured data of Jinghuiqu irrigation district in Shaanxi Province from 2013 to 2014,the early warning and decision simulation of drought crisis in Jinghuiqu irrigation district is carried out.The results are compared with the official monitoring results to verify the rationality of drought crisis diagnosis system and resistance mechanism.Furthermore,two single factor indexes include standardized precipitation index(SPI)and the soil moisture index are used to verify the accuracy of those results obtained in this study in the same period,in order to confirm the scientific and rationality of the drought early warning system established by this study from other side.The final results show that,the drought crisis diagnosis and early warning system established in this paper has comprehensively considered the drought status and water source situation and other factors,and it can successful characterize the development trend of drought events from the two levels of drought and water regime(i.e.,demand and supply).In addition,this drought crisis diagnosis and early warning system contains more information about drought resistance than the SPI and soil moisture indicators,and it exactly has more guiding significance for the process of drought resistance.On the other hand,the comparison results also show that the drought crisis diagnosis and early warning system is a more scientific and reasonable,comprehensive and perfect system,and through it we can simulate and develop the scientific and reasonable drought emergency measures,which can effectively alleviate the drought irrigation district in the future.As a result,the drought crisis early warning and decision framework established in this study has a strong application value in irrigation district. |
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