| The source area of the Yellow River in Tibetan Plateau,as an important component of the Three River Souse in China,is a pivotal hydrological and climate regulation hub around East Asia.In the past 30 years,this region experienced a large range of landscape fragmentation and ecological functional degradation,driven by climate change and aggravation of human activities.The subsequent implementation of ecological and environmental protection projects and the intensified land use have made great contributions to the restoration of its ecological status,within it,the accelerated urbanization process,is bound to drive the change of the alpine ecosystem.However,of the intensified use of land source,in forms of the construction of small towns,and the transformation of the industrial structure,there is unknown of its spatial suitability,growth status and influence.This paper a)conducted a comprehensive suitability evaluation of urban land use in the source region of the Yellow River basin based on the Land Suitability Assessment with 13 indicators,including natural,social and ecological safety factors.b)simulated and analyzed the expansion of small towns and their UGBs in the source region of the Yellow River from 1997 to 2017,and establishes three scenarios with cellular automata software,(i.e.unregulated scenario,ecological-developed scenario,and strictly regulated).Explored the future spatial optimization models in this region.c)Analyzed the impact of intensive land use on NDVI in the study area through RS and GIS tools.d)And predicted the intensified land use pattern through the calculation of landscape indicators in different urban growth scenarios.This study could provide the ecological restoration project with data and methodology supports.The main results of the study include:(1)The comprehensive evaluation of land use suitability shows that: In the study area.Nearly 87% of the area is the basic suitable area for urban land use,it distributed continuously throughout the entire study area.Nearly 13% of the area belongs to the unsuitable area for urban land use.It distributed in blocks and points,mainly distributed in the western edge,northern edge and southeastern margin of the study area.Only 0.06% of the area(43.42km2)is suitable for urban land use,it scattered in the middle and the southeast area of the study area.This result is consistent with the actual distribution of urban build-up in the study area.(2)Cellular automaton simulation results show that:a)Under the unplanned scenario that without ecological limitation,the expansion area of the built-up in the year 2040 reached 344.81 km2,which was 3.38 times the planned area of the built-up area in 2020,and the expansion rate in 30 years was 1.2 times of its between 1997 to 2017.Built-up areas have a great impact on ecological protection zones,and their expansion rate is inconsistent with the population growth rate in the area and does not meet the requirements of sustainable development.b)Under the scenario of intensified development that highlighted the urban growth driving force from transportation and tourism,the total area of built-up areas in the study area in 2040 is 276.17 km2,which is 2.71 times of the planning one by 2020,is slightly lower than the expansion rate between 1997-2017.this scenario,under the limitation from transportation,tourism points and ecological limitation,has a highest edge density(ED)among all the senses.The rate of expansion is more balanced with the population and economic growth of the area,which makes them ideal model for continuous development.And the growth rate of built-up area in this scene showed a growth to decrease trend of in the longitude range of the study area.c)In the strictly controlled situation,the total area of the built-up area in the study area in 2040 is 236.99 km2,which is 2.32 times the planned area in 2020,and the expansion rate is only 0.8 times of 1997-2017.Built-up areas have minimal impact on ecological protected areas,and their expansion rate may not be able to meet the needs of economic growth.(3)The effect of intensive land use on NDVI values revealed that the degree of impact of intensive land use on vegetation cover in typical regions,sorting by Winter Pasture> Tourism Area> Summer Pasture.It could be concluded that the cellular automata model using the results from land suitability evaluation performs well in simulating the urban land use scenarios under various intensified patterns in the source region of the Yellow River.In the results of the CA simulation,it was determined that the intensive scenario driving by traffic and tourism is an ideal spatial planning scheme for coordinating the ecological and production functions in the research area.This scenario may mitigate the current ecological pressure of intensified livestock husbandry in winter pasture.It focuses on the central area,and its implementation requires more complex engineering design for build-up. |
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