| Jing River basin,located in the middle of the loess plateau,is one of the birthplaces of Chinese agriculture and animal husbandry civilization.With the growth of population and economic and social development,water resources have been closely coupled and coevolved between the social system and the natural environment in the Jing river basin over a long period of time,resulting in many water and ecological environmental problems such as ecological degradation,deterioration of water quality and reduction of water resources in the basin.It is challenging to find a sustainable,green and high-quality development path in the gap between the social system and the natural system,which not only guarantees the economic development of the river basin but also gives consideration to ecological protection and ecological restoration.It is difficult to strike a balance between the human-water relationship between the social system and the natural system.At the same time,in the face of climate change risks and social challenges,the interaction between the social system and the hydrological system needs to be deeply discussed.In view of this,based on the study summary and baseline analysis of the Jing river basin,this paper systematically explored the evolution rules of social hydrological and meteorological elements in the Jing river basin,proposed a new impact assessment model for the correlation between factors,and conducted an impact assessment for the mutual feed-water of precipitation and runoff.This paper sorts out the concept,characteristics and classification of social hydrology,and roughly discusses the mechanism of social hydrology in Jing river basin.An empirical model was established to describe the change of cultivated land area proportion and total water consumption in the social system.Based on the water balance theory of social hydrology,the equilibrium analysis and the equilibrium control strategy analysis of social hydrology in Jing river basin were carried out.The main conclusions were as follows:1.Under the background of human activities and climate change,hydro-meteorological elements in the Jing river basin show the spatio-temporal variation.The average annual maximum and minimum temperatures in Jing River basin showed an increasing trend.The average annual maximum and minimum temperatures in the two periods from 1959 to 1990and from 1990 to 2018 increased by about 0.5?,indicating obvious climate warming.The spatial variation pattern of precipitation is similar to that of air temperature.The precipitation increases gradually from the northern part of the basin to the southern part of the basin.The pan evaporation increased in the north and south of the basin,and decreased in the middle part of the basin.The perennial average relative humidity in Jing River basin increased gradually from north to south,with the lowest average relative humidity in the far north and the highest average relative humidity in the southwest.In terms of time,from 1959 to 1990to 1990 to 2018,the perennial average relative humidity in the northern part of the Jing river basin increased about 0.02,while the perennial average relative humidity in the central and southern parts of the Jing river basin decreased about 0.02.2.The evolution of social factors and hydro-meteorological elements in Jing River basin was systematically revealed through the combination of long-range correlation analysis methods,time domain scale correlation analysis methods and trend and variation analysis methods.In terms of single factor,the trend and variation characteristics of water resource supply and demand,water consumption,and hydro-meteorological factors are revealed,and the sustainability of the trend changes of hydro-meteorological elements is also understood through long-term auto-correlation diagnosis.In terms of two factors,the paper mainly reveals the structural evolution and mutual feed-back mechanism among hydro-meteorological elements,and the mutual feedback between social factors and hydro-meteorological elements.In terms of the three factors,the mutual feedback of hydro-meteorological elements in different time domains and scales was studied,and the influence of climate change and direct human activities&underlying surface changes on the mutual feedback of precipitation and runoff was evaluated qualitatively.3.The concept,connotation of socio-hydrology and differences between socio-hydrology and other related disciplines are introduced.Based on this,socio-hydrology is further classified into four categories:drought socio-hydrology,urban socio-hydrology,flood socio-hydrology,and mechanism socio-hydrology.The different categories reflect the unique interaction mechanism between different social and hydrological systems,as well as the mechanism problems of different social and hydrological coupling systems that need to be solved.Based on the water balance theory of socio-hydrology,the mechanism of socio-hydrology in Jing river basin is analyzed:the average ratio of ecosystem evapotranspiration in the Jing river basin from 1990 to 2015 was 0.536,and the average ratio of social system evapotranspiration was 0.464.The evolution of socio-hydrology during 1990-2015 can be divided into two periods.During the period of 1990-2000,the social system preempted the ecosystem and consumed water.Between 2000 and 2015,the trend is likely to continue.The mediation of the two stages reflects the reversal of the primary and secondary status of the basin's economic and social development and ecology.It can be concluded that from 1990to 2000,in order to meet many human needs such as economic development within the social system,water consumption kept increasing,with development as the first priority.From2000 to 2015,in order to meet the sustainable ecological environment in the river basin and achieve good ecological goals,ecological water consumption kept increasing,reflecting the first priority of ecology.4.Equilibrium analysis based on framework of socio-hydrology shows that after 1988,the harmony degree(HD)of annual runoff dropped sharply to the lowest value;after 1995,the harmony level remained in the state of"basic disharmony".The change of annual runoff harmony degree was directly driven by annual runoff,and the sharp decrease of annual runoff harmony degree after 1988 may be caused by the sharp decrease of annual runoff;From 1990 to 2000,the harmony degree of water consumption(evapotranspiration)of the socio-ecosystem in the Jing river basin was basically stable,with the average level of harmony being"basically harmonious".After 2000,the harmony degree of water consumption dropped sharply and fluctuated greatly,which was in a state of disorder,and the average level of harmony was"basically disharmonious".In four kinds of harmonious rule(1:6:6,1:8:8,1:10:10 and 1:12:12),the harmony degree all sharp declined in 1998 years and then fluctuated,and annual HD decreased during 1990-2000 year periods to 2000-2010year periods.The amplitude of change under different harmony rules from big to small is1:6:6,1:8:8,1:10:10 and 1:12:12,reflecting that the smaller the proportion of"divergence"required by annual runoff as a harmonious participant,the smaller the degree of harmony reduction will be.5.South-to-North Water Diversion Project has reshaped the water resources landscape of our country.The western route project will benefit water-scarce provinces such as Gansu and Qinghai in the upper and middle reaches of the Yellow River.It will be a powerful external force to balance water resources in the river basin among the social system,hydrological system and ecological system.The harmony rules among hydrology,society and ecology were abbreviated into harmony rule 1,harmony rule 2,harmony rule 3 and harmony rule 4 corresponding to 1:6:6,1:8:8,1:10:10 and 1:12:12.Based on the optimal harmonious behavior under different harmony rules,the water resource equilibrium analysis was carried out.Under harmony rule 1,the minimum equilibrium allocation by external force(water diversion)for many years was 3.587 billion m~3.Under the harmony rule 2,the minimum equilibrium allocation by external force(water diversion)for many years is 3.112billion m~3.Under the harmony rule 3,the minimum equilibrium allocation by external force(water diversion)for many years is 2.827 billion m~3.Under the harmony rule 4,the minimum equilibrium allocation by external force(water diversion)on average for many years is2.6369 billion m~3. |
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