| Ningxia Hui Autonomous Region is located in the northwestern part of my country,with strong evaporation in the region,uneven distribution of precipitation in time and space,and the Yellow River passing through Ningxia.With the increase in human activities,rapid economic and social development,and intensified globalization,the evolution of rivers and lakes in Ningxia has undergone significant changes.This paper analyzes the dynamic evolution process of inland rivers and lakes in the region from the time series changes,spatial changes,and representative river and lake evolutions by extracting the river and lake water body information from the remote sensing images from 1980 to 2018,and based on the multi-year temperature and precipitation,Runoff,water resources,water supply and land use,engineering measures and other factors,a comprehensive analysis of the driving mechanism of river and lake evolution,and finally put forward countermeasures and suggestions for river and lake protection,the results of this research on the evolution of rivers and lakes in Ningxia And protection has important theoretical significance.The results achieved in this article include the following parts:(1)Preprocess the acquired remote sensing images,establish the relevant parameters needed to extract river and lake information from the remote sensing images,and select the improved normalized difference water index(MNDWI)according to the actual situation of the study area.Water extraction index.For the collected non-remote sensing data,determine the river and lake evolution analysis parameters,including the lake evolution intensity index for the lake,the M-K test method and the Pearson correlation analysis method for correlation analysis of meteorological data and other data.(2)Based on the geographic information system technology,the time series analysis method is used to carry out data statistics on the surface area of rivers and lakes in Ningxia,and analyze the law of changes in the surface area of rivers and lakes over time.During the 30 years from 1988 to 2018,the water surface area of rivers in Ningxia has shown an overall increasing trend.The water surface area of the river expanded to244.22 km~2 in 30 years,and the rate of increase was 8.14 km~2/a,which was 2.32 times that of the water surface area in 1988;the water area of lakes in Ningxia showed an increasing trend,and the lake area expanded to 668.76 km~2 in 30 years.,The increasing rate is 22.29km~2/a,and the range of change is 5.13 times that of the lake area in 1988.(3)Based on the spatial analysis of the evolution of rivers and lakes in the whole area of Ningxia,the Ningxia region is divided into three major geographic units according to the multi-year average precipitation contours,namely the northern yellow irrigation area,the central arid area and the southern mountain area.Data analysis can be used The area of rivers and lakes in the three major regions has shown an increasing trend.Among them,the rivers and lakes of Ningxia are mainly distributed in the northern irrigation area of the Yellow River,and the water surface area accounts for more than 90% of the river water surface area of the whole region.The water surface area of the river in the northern Yellow River irrigation area has the largest change.In30 years,the river surface area has expanded by 233.84 km~2 and the expansion rate has been 0.78 km~2/a;while the central arid area and the southern mountain area have increased by 11.06 km~2 and 3.85 km~2 respectively.The area of lakes in the northern Yellow River Diversion Irrigation District has the largest change,with a lake area expansion of 95.37km~2 within 30 years;the central arid zone has the largest change in lake area,with a lake area expansion of 15.33km~2 in 30 years,and the total expansion rate exceeds the existing lake surface in 1988.20 times the area.(4)Through time series analysis of related data such as temperature,precipitation,runoff,and water resources in Ningxia,from 1980 to 2018,the average temperature of Ningxia showed a rising trend and passed the significance test,Ningxia’s multi-year average temperature is 8.7℃;the annual average precipitation shows a slow upward trend,and the entire district’s multi-year average precipitation is 272.65mm;the annual runoff changes of the Shizuishan and Xiaheyan hydrological stations show a fluctuating trend,first decreasing and then increasing,The average runoff for many years is 27.091 billion m~3 and 29.951 billion m~3 respectively,and the time series of the annual runoff are the same.(5)After comprehensive consideration,select representative rivers of Ningxia:Yellow River,Qingshui River,Kushui River,Hulu River,and lakes: Xinghai Lake,Shahu Lake,Zhenshuo Lake,Yuehai Lake,etc.for evolution analysis.Among them,the water area of the selected representative rivers has shown an increasing trend in 30years;among the selected representative lakes,the areas of Xinghai Lake,Zhenshuo Lake,and Yuehai Lake have shown an increasing trend in 30 years,but the water area of Shahu Lake has increased in 2010.The former showed a growth trend,and it has shrunk after 2010.In addition,from 1988 to 2018,the evolution intensity index of lakes in Ningxia was 17.10,among which the evolution intensity index of Zhenshuo Lake was the largest at 19.11,indicating that the area of Zhenshuo Lake changed the most drastically.(6)Use M-K detection method and Pearson analysis method to analyze the correlation of selected driving factors to reveal the relationship between the evolution of rivers and lakes in Ningxia and the driving factors.The results show that the average annual temperature has a good correlation with the water surface area of the whole region.The average precipitation and runoff have a positive correlation with the lake surface area for many years,and the water diversion volume of the Yellow River in Ningxia has a negative correlation with the lake surface area.Significance test.Among them,temperature and the amount of water diversion from the Yellow River are the main factors affecting the evolution of rivers and lakes.At the same time,factors such as land use,construction of water conservancy projects,and connection of water systems have had an important impact on the evolution of rivers and lakes,which also reflects that human activities and other factors play an important role in promoting the evolution of rivers and lakes.On this basis,put forward some river and lake protection policies,such as vigorously carrying out river and lake resource monitoring,realizing the optimal allocation of water resources in the river basin,promoting the development of lakeside water environment and ecological environment investigation and restoration projects,and strengthening river and lake protection and publicity and education,Improve the legal and policy system for river and lake protection. |
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