Impacts Of Changing Environment On Blue And Green Water Resources And Their Response Characteristics In The Lianshui River Basin

Blue water resources represent liquid water of river,lake,wetlands and underground aquifers.Green water resources indicate that the precipitation infiltrate into the soil unsaturated layer and return to atmosphere by the plant transpiration and soil evaporation through hydrologic cycle,which is an important basis for the production of agricultural crops,however,it is usually ignored by traditional water resources management in the river basin.Taking Lianshui river basin as the research object,SWAT distributed hydrological model was used to simulate and predict the amount of blue and green water resources under different scenarios to assess the impact of changing environment on blue and green water resources,and to analyze the applicability of the game theory framework of blue and green water management in the Lianshui river basin.The SWAT distributed hydrological model was constructed based on the spatiotemporal input data of DEM,land cover,soil attribute,meteorological conditions,agricultural irrigation and water resources utilization in the Lianshui river basin.After analysis of the parameters sensitivity of blue and green water simulation according to LH-OAT method,the PSO particle swarm optimization algorithm and Kling-Gupta efficiency(KGE)objective function were used to parallel calibrate the model parameters of blue and green water through the observed runoff of Xiangxiang station and MOD 16 evapotranspiration data in the Lianshui river basin.Moreover,the Nash-Sutcliffe efficiency(NSE),certainty coefficient(R2),percent bias(PBIAS),p-factor and r-factor were selected to evaluate the simulation results of blue and green water and its uncertainty.The results of simulated evaluation and uncertainty analysis indicated that the constructed SWAT distributed hydrological model of the Lianshui river basin were credible both in the calibration and validation period under different scenarios,and the uncertainty of blue and green water simulation was in the confidence region.Specific research contents and obtained conclusions of this study are listed as following:(1)To simulate and analyze the influence and contribution rate of climate change and land use change on blue and green water resources in the Lianshui river basin from 1985 to 2014.According to land use and land cover conditons in 1990,2000 and 2010,simulated scenarios have been divided into three meteorological background periods of 1985-1994,1995-2004 and 2005-2014 respectively.The results of scenario comparative analysis showed that the blue water in the Lianshui river basin continuously decreased and the green water continuously increased due to the climate change in the past 30 years,while the land cover change caused the relative increase of blue water and the decrease of green water.But annual average blue water resources(40.7%)decreased and annual average green water resources(59.3%)increased on the whole.Furthermore,the influence of climate change on blue and green water rose(blue water from 71.4%to 86.3%and green water from 68.2%to 88.7%),and the impact of land cover change was relatively lower(blue water from 28.6%to 13.7%and green water from 31.8%to 12.3%).Hence,under the spatial pattern of land use and land cover,the blue and green water management in the Lianshui river basin should take full account of the impact of local climate change.(2)To simulate and predict the temporal trend and spatial distribution of blue and green water resources in the Lianshui river basin under the future climate change from 2020 to 2079.Future climate change have been divided into two climatic background periods of 2020-2049 and 2050-2079,which had generated from four typical concentration paths of RCP 2.6,RCP 4.5,RCP 6 and RCP 8.5 in the HadGEM2-AO atmospheric model.Consequently,the scenario predicton results of blue and green water indicated that the Lianshui river basin had some extent of decrease in blue water resources(1.4-17.3%)and green water storage(7.8-19.7%),while the green water flow(3.5-12.4%)increased under different RCP emission scenarios from 2020 to 2079.Even taking the parameter prediction uncertainty range of 95PPU into consideration,the future growth trend of green water flow is also obvious.Therefore,it is of strategic importance to integrate green water resources into future water resources planning of Lianshui river basin and to achieve comprehensive management of blue and green water resources.(3)Game modeling application analysis of blue and green water management in the Lianshui river basin.Based on the basin-wide water balance and concept of blue and green water,this paper takes green water resources into the basin water resources management.In the framework of the green water credit concept and game theory analysis,SWAT distributed hydrological model in combination with the multi-objective optimization and scenario comparison analysis optimize the allocation of watershed blue and green water resources,and coordinate interest conflicts between upstream and downstream through green water management and green water compensation.Accordingly,the game theory framework of basin blue and green water management is exploratory proposed.This method can identify and analyze game space,game structure and Nash equilibrium of basin blue and green water management by game modeling and can calculate green water compensation standards and Pareto optimal in different blue and green water management scenarios by the improved optimization method and its cooperative game theory constraint conditions.Moreover,the game theory framework of blue and green water management has been applied to the Lianshui river basin,and the game analysis results of revenue change between upstream and downstream,green water compensation standard and Pareto optimal solution set show that the overall socio-economic and ecological benefits of the Lianshui basin improved significantly.Its Pareto-optimal income increased by an average of 272 million yuan/a,and the average annual green water compensation standard was 1.94 yuan/m3 and 1253.7 yuan/hm2,thereby the proposed game theory framework of blue and green water management has good applicability and feasibility in the Lianshui river basin.Consequently,this method can provide relevant theoretical basis and technical reference for the future river basin pilot study of blue and green water management and its green water compensation standard estimation,which has some extent application value and practical significance.