| The People's Victory Canal Irrigation District is the first large Yellow River irrigation projects after the establishment of the People's Republic of China?1949?in the lower reaches of the Yellow River basin.With the rapid development of social economy,the influences of human activities on the irrigation areas are more frequently,which lead to significant changes in regional water cycle and intensified contradiction of water supply and demand.The imbalance between supply and demand of water resources and instability of agricultural water resources will be further intensified under global warming.Therefore investigation the formation and transformation and allocation of water resources under global warming has important significance in efficient utilization of water resources and management in irrigation and drainage system.In this paper,the multi-water resources cycling and conversion and optimal allocation were studied by using simulated and optimal method.The main research contents and conclusions are as follows:?1?According to irrigation-drainage systems?water intake,conveyance,distribution and drainage?,the multi-water cycle and transformation model was established.The average annual transforming relationships of multi-water resources were then simulated and analyzed.It is feasible to recognize the relationships of“four-water”transformation by establishing a multi-water cycle and transformation model according to irrigation-drainage systems.The model can simulate the processes of multi-water cycle and transformation well.The evapotranspiration and seepage volume were considered as transformation in the multi-water resources cycling and conversion.The average annual transforming relationships of multi-water resources are 985.00 million m3,175.78 million m3,889.16 million m3 and12.81 million m3 in the system of water intake,conveyance,distribution and drainage,respectively in2001-2010.The surface water,the soil water and the groundwater have negative recharge trends,which reduces the available amount of local water resources.This paper provides a new way for understanding deeply the process of water transformation through interface between surface water,groundwater,soil moisture or atmospheric water.?2?A technical approach for assessing the impact of climate change on water demand was presented and then agricultural,municipal and industrial water requirements were projected based on the multi-model ensemble simulations of five global climate model.The projected water demand would increase for municipal,industrial and ecological water requirements under the Intergovernmental Panel on Climate Change representative concentration pathway 4.5?RCP4.5?scenario.Comparing with the results of water demand prediction by using traditional technique,the irrigation water requirement is quiet different from that in crop growth stages under the RCP4.5 scenario.And the irrigation water requirements of summer maize and spring planted cotton would significantly increase with P=75%.Meanwhile,the municipal and industrial water requirements are also increased.Generally,regional contradiction of water supply and demand may become much more intense under the future climate change scenario.Therefore,the impact of climate change should be considered in regional water demand management.?3?Based on the large system decomposition-coordination theory,an optimal allocation model of regional multi-water resources with four layer structure was established.The water diversion for considering the impact of climate change was presented.The multi-water optimal allocation model was established by taking the maximum net economic benefit as the objective function.The model structure had four layers:1)for a single crop,2)for multiple crops,3)for multiple water departments and 4)for sub-regions and were combined with muti-water supply.This model could realize the multi-water optimal allocation in crop,water departments and sub-regions in the study area.Furthermore,the model solution was simplified by the hierarchical optimization method.The results show that water supply would meet the municipal,industrial and ecological water requirements,but there is a shortage of water for agricultural department in normal year?P=50%?.In dry year?P=75%?,industrial water shortage is found in part of study area.That would be further aggravated and the target benefit value would be obviously reduced under future climate change scenario due to the significantly increasd agricultural water requirement.Research results can provide the scientific basic for regional water management and adaptability to future climate change. |
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