Spatial-temporal Characteristics Analysis Of Hydrological System Complexity In Harbin Area And Its Influence Effect Study

Harbin is the provincial capital of Heilongjiang Province and the megacity with the largest land area and the second-largest population in provincial cities of China which is in an important strategic position in the revitalization of the old industrial base in Northeast China.In recent years,along with the rapid industrialization and urbanization accelerated by human activities,changes of underlying surface condition in Harbin region are produced and cause a series of hydrological system problems which affect the prediction and sustainable utilization of urban water resources.In Harbin region,with the phenomenon of global water shortages and the view of sustainable development have been paid more and more attention,the complexity of water resources is measured,spatial variation rule of water resources is revealed,the influencing factors are analyzed and on this basis the optimal allocation of water resources is conducted.Research provides a reference mode for the coordination of society,economy and ecology.The theory of entropy method used in the complexity measure of hydrological sequence is relatively mature.Thus,permutation entropy,wavelet entropy and multiscale entropy which are relatively novel are used to measure the complexity of monthly precipitation sequence and daily groundwater depth sequence in Harbin region in this paper respectively,and spatial distribution map in accordance with the grade division of complex values.Results of three kind of entropy theory are Comparative analyzed to determine the best theory.Multiscale entropy has the most advantage in entropy theory,but the values of the important parameters in the traditional multiscale entropy are randomly determined in the empirical range that may influence the complexity values.In this study,Particle Swarm Optimization algorithm is used to select the optimal parameter combination and the complexity order of each region in Harbin is determined.Synthesize complexity of precipitation and groundwater to complexity of regional water resources(CRER)using entropy.The CRER values of Yanshou,Shangzhi and Tonghe are all at Grade-I,Shiqu,Mulan,Bayan,Binxian,Wuchang and Yilan are at Grade-II,Shuangcheng and Fangzheng are at Grade-III.Principal component analysis(PCA)is introduced to analyze the driving mechanism of water resources complexity in Harbin region and main driving factors are determined.By compared the complexity grades of water resources with driving mechanism grades,the complexity grades and the driving mechanism grades of Wuchang,Mulan,Fangzheng are same.The difference of complexity grades and the driving mechanism grades of downtown,Yanshou,Tonghe,Bayan,Binxian,Yilan and Fangzheng are 1.The difference of complexity grades and the driving mechanism grades of downtown,Yanshou,Tonghe,Bayan,Binxian,Yilan and Fangzheng are 2.This indicates that the driving mechanism influences the water resources complexity but the influence degrees of different factors are different.The multi-objective water resources allocation model is introduced by decision variables,objective function,constraint condition and optimization of parameters and then used in Harbin region to allocate the water resources on 2020 and 2030 reasonably using the CRER as constraint condition.Using the water quato method to forecast the demand of domestic water,agricultural water and industrial water in Harbin.The multi-objective Genetic Algorithm is used to solve the model,and the optimal allocation of water resources in Harbin region in 2020 and 2030 is obtained.This research provides foundation for reducing the pressure of urban water shortage further and realizing the monitoring and management of hydrological environment,meanwhile,provides scientific basis for other relevant departments.