Hydrological Process Analysis and Water Resources Management for River Basin in Arid RegionCN
Abstract：Water resources are essential for sustainable development of socio-economy and eco-environment in arid region.Due to intensifying climate change and expanding human activity,water resources in arid region have undergone significant alterations in quantity and distribution,posing challenges to water resources management.Water resources management is a complex task involving hydrological simulation and prediction,as well as water allocation.Various uncertainties derived from random water flows,changed water policies and imprecise economic data may exist in water resources system,aggravating the difficulty in water resources management.Consequently,it is imperative to advance a systematic method to reflect such complex uncertainties,promote hydrological simulation and prediction accuracies,and identify effective water resources management alternatives for supporting sustainable development of arid region.Therefore,this thesis has analyzed hydrological process for identifying the main factors that affect hydrological simulation and prediction,and developed stochastic analysis methods for formulating robust water resources management strategies.In detail,(1)Semi-distributed land-use based runoff process(SLURP)hydrological model is developed for simulating hydrological process in Kaidu River basin.Twenty-four combinations of digital elevation model(DEM)resolutions and subbasin levels are explored for analyzing their effects on runoff simulation.Such analysis can be used for quantifying the uncertainty of river basin’s spatial information on model simulation,disclosing the interaction between DEM resolution and subdivision level,as well as identifying the optimal inputs.Results show that runoff variation is more sensitive to subbasin levels than that to DEM resolution;combination with 200 m DEM and 183 subbasin levels is optimal in terms of model performances.(2)A multiple climate scenarios-based stepwise cluster-SLURP modeling system is developed through coupling global climate models(GCMs),stepwise cluster downscaling technique and SLURP hydrological model.Then,the developed modeling system is applied to the Kaidu River basin for exploring climate change impacts on future runoff.The developed modeling system has advantages in tacking uncertainties derived from climate models due to differences among physical and emission scenarios,and reflecting nonlinear and discrete relationships between predictors and predictands without functional hypothesis in model simulation.Results show that the temperature in spring and winter would largely increase;precipitation in spring and autumn would increase;the streamflow in spring is the most sensitive to climate change.(3)An integrated simulation-optimization based allocation modeling system(ISAMS)is proposed through coupling GCMs,stochastic weather generator,and interval multi-stage stochastic programming(IMSP)method.The ISAMS can not only handle uncertainties expressed as probability distributions and interval values but also reveal climate change impacts on water resources allocation under different projections of GCMs.ISAMS is then applied to Kaikong River basin for assessing climate change impacts on water resources management strategies.A variety of decision alternatives about water allocations adaptive to climate change are generated under combinations of different GCMs and ecological water release plans.Results could help balance system benefit and ecological protection,as well reduce the risk of water shortages in adaptation to climate change.(4)A possibilistic-flexible chance-constrained programming(PFCP)method that is capable of addressing multiple uncertainties expressed as possibilistic distributions,flexible variables,and probabilistic distributions existed in water-land nexus system(WLNS)is developed.PFCP can help gain in-depth analysis of the tradeoffs between system benefit and reliability of satisfying constraints.Then,the proposed PFCP method is applied to the lower reaches of Amu Darya River basin for assessing the impact of irrigation efficiency on the WLNS management,where 1080 scenarios are analyzed in association with different irrigation schemes,violation risk levels,and satisfactory degrees.A number of water and land resources allocation alternatives for different irrigation districts and crops are generated.Results indicate irrigation mode with efficiency of about 0.61 is an effective option in adaption to changed water availabilities,which is beneficial for pursuing balance between water and land relationships.(5)A stochastic fuzzy fractional programming(SFFP)method is developed through integrating techniques of chance-constrained programming,fuzzy credibility programming,and fractional programming into a general framework.SFFP can deal with uncertainties expressed as random variables and fuzzy sets,as well as reflect multi-objectiveness of the system.A SFFP based water-food-energy nexus system management model is established for Kaikong River basin,where impacts of uncertainties related to changed water availabilities,water demands,as well as pollutant and carbon dioxide emission allowances on water allocation,food production and electricity generation are explored.Results show that coal-fired electricity and vegetables are sensitive to the changed water availabilities and demands,which could help decision makers implementing water resources management for ensuring security of water,food and energy.In summary,this thesis has explored the effects of river basin’s spatial resolution and climate change on hydrological process in the Kaidu River basin,which helps reveal the main factors influencing runoff and improve model performances in simulation and prediction.Stochastic-analysis-based water resources management models are developed for river basin in arid region,where optimal water allocation strategies,crop planting modes and electricity generation alternatives are obtained.These findings can help balance the contradictions among climate change,water availability,food production,energy generation,and eco-environmental protection,promote water use efficiency and alleviate water shortage risk in arid region.