| Qinghai Qaidam Basin is the best resource of salt lake in China,and it is also the region with the highest degree of industrialization of salt lake resources exploitation.Accompanied by the continuous deepening and scale of salt lake resources development,it has also brought a series of resources,environment and ecological problems.Accurately grasping the interrelationship between the development of salt resources in the region and the change of landscape pattern,can better reveal the evolutionary laws and interaction coupling mechanisms of artificial and natural systems in the Salt Lake region.Based on the Landsat series of satellite remote sensing images from 1972 to 2015,through field investigation and remote sensing interpretation analysis,this paper quantitatively analyzes the variation of lake surface water area of the main salt lakes in the industrialized stage and the change of landscape pattern of typical areas in Qaidam Basin.Combining with the current situation of the exploitation of the Qaidam salt lake resources,This paper explores the impact degree and influence mechanism of the salt lakes exploiting behavior on lake surface changes in the Qaidam Basin and in landscape pattern variations in the surrounding area of Qaidam Basin.The purpose of this paper is toproviding basic reference materials for the rational development and sustainable use of salt lake resources.,it also has certain reference significance for the protection of regional ecological environment.First of all,this study has collected data about the existing geological environment,resource exploitation status,and climate changes data in the Qaidam Basin.Referencing this data,through the preprocessing of multi-period remote sensing images,combining with topographic maps,field survey data,and other sources of literature data,this paper identifies the optimal band combinations required for extraction and then establishes a remote sensing interpretation signature for typical features of salt lakes.This research extracts typical feature information by human-computer interactive interpretation of remote sensing images.And then the extracted information is converted into attribute data and related analysis charts are drawn.Finally,combining with the status of resource development in the Qaidam Basin,selecting some landscape pattern change indices such as landscape diversity,landscape fragmentation,landscape spatial transfer index,and other suitable characteristics of the salt lake region,the influence and driving forces of a series of behaviors in the salt lake resource development process on the lake surface change and the surrounding landscape pattern change have been analyzed in depth.The research shows that:(1)The total area of surface water in salt lake experienced two periods of increase and decrease between 1972 and 2015.Overall,it decreased,with a total decrease of 189.25 km~2.Before 2005,the change trend of the total area and the area of every salt lake is“increase-decrease-increase”,after 2005,the change trends of salt lakes with different degrees of exploitation are significantly different.The area of undeveloped salt lakes has increased,and the area of salt lakes at the experimental stage has remained basically unchanged,and the area of salt lake in the industrialization stage has drastically decreased.It shows that climate factor,especially rainfall in the basin is the key factor controlling the variation of salt lake area i in the undeveloped stage and experimental stage of resource exploitation.Salt lake resource exploitation behavior is the key factor to control the salt lake in the industrialization stage.The impact of resource exploitation on the water cycle and water balance in the salt lake area is mainly achieved through the construction of salt pan,the construction of dams,the extraction of intercrystalline brines and the discharge of used brines.The area of salt pan in the basin has increased greatly in the past 40 years,at the same time,a large number of lake tables and intercrystalline brines were extracted,which increased the consumption of salt lake surface by evaporation,resulting in a decrease in surface water in salt lake.Some companies built a large number of dams,diverted or cut off the source of supplemental water in the upper reaches of the salt lake,reduced the natural recharge of the of salt lake,and caused the lake surface to shrink.Simultaneously,the discharge of used brines changed the original spatial distribution of the lake surface of the salt lake,which caused a huge impact on the changes in the lake surface of the salt lake.At the same time,it also changes the region's water cycle characteristics and balance mode.(2)Due to its location in arid and deserted areas,the landscape composition of Taijin Area is relatively single.The SHDI index is around 0.6 shows that the level of landscape diversity is relatively low,which mainly controlled by a few landscapes(dry salt flats and deserts).It is a typical desert landscape,and the natural landscape dominates.From 1990 to 2005,dry salt flats,salt lakes and deserts were the main landscapes in the lake area.Due to the low level of resource development,Changes in landscape area and landscape pattern were mainly controlled by climate factors.Changes in temperature and precipitation dominate variations in various landscape area and landscape fragmentation.Overall,the extent of changes in various types of landscape is relatively low.At the same time,the intervention of human activities(salt lake resources exploitation)began to form some man-made landscapes,which increased the types of landscapes and caused an increase in landscape diversity,but the overall diversity is still at a low level and the ecological environment is fragile.During the period from 2005 to 2015,salt lakes were reduced in a large area.The development of salt lake resources affected the landscape pattern in the salt lake area.The main manifestations were:increased landscape spatial distribution changes,increased landscape types,increased landscape fragmentation,and changes in landscape diversity.Swamps and rivers are most affected by human activities.Spatial distribution has undergone large-scale transfer with a transfer index of up to 99.The area is reduced and tends to be broken,which seriously affects the living and breeding space of the organisms in the region,and which is not conducive to the development of biodiversity.In 2015,the area of swamps and rivers decreased by 73.89%and 56.96%respectively.Although the type and proportion of human landscapes have increased,the landscape is still dominated by dry salt flats and deserts,and the landscape diversity is still at a low level.Changes in the landscape pattern indicate that with the deepening of human intervention in the Qaidam Basin,human activities will have more and more obvious effects on the landscape pattern,and the spatial distribution will tend to be fragmented.In some areas,the lakes have dried up or their area has shrunk.As a result,the lake basin has become bare,and the area of dry salt flats has increased,becoming a source of dust storms.The habitat and reproduction environment of species living in the native environment has changed,and the number and species of freshwater organisms have increased with the artificial rain flood supplementation project.The species and diversity of biological species in the research area are changing. |
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