渭干河—库车河三角洲绿洲生态风险评价及预警研究

发布时间：2018-01-05 16:01

本文关键词：渭干河—库车河三角洲绿洲生态风险评价及预警研究　出处：《新疆师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着人口的急剧增多及人们对资源的不合理配置,导致生态系统自身的调节能力不断下降,人们所处的生存环境变得更加脆弱,承受的风险增加。基于此选择了西北地区典型冲积洪积平原之一的渭干河-库车河三角洲绿洲作为研究区,运用遥感方法及技术,结合遥感影像、野外实测数据及研究区DEM图、土地利用图、社会经济统计资料等数据,进行生态风险的评价及预警。在时间上选择夏秋季的该地区1989、2001、2007、2013年的遥感影像通过监督分类提取研究区土地利用/覆盖景观情况,并基于此对研究区景观格局动态进行分析及预测,接着以由景观格局指数构建的生态风险指数对研究区生态风险进行评价,最后选择生态预警指标,运用BP神经网络算法构建出研究区生态风险的预警模型,得到的主要结论如下:(1)1989-2013年,渭干河-库车河三角洲绿洲的景观类型没有发生变化,但各景观类型的面积及比例变化较大,整体表现为绿洲面积扩张的趋势,在2013年耕地面积达到了41.74×104 hm2。耕地与草地之间的转化较为显著,最大时达到了14.32×104 hm2。运用CA-Markov模型预测出了渭干河-库车河三角洲绿洲2019年景观分布情况,总体变化趋势仍为绿洲面积的扩张,达到55.48×104hm2。景观上表现为林地与盐碱地的增加及草地的减少。(2)1989-2013年研究区景观破碎化程度降低,斑块间聚集度增强,最大优势景观的连接性增加,各斑块类型的数目与面积比例朝向不均衡化发展。1989年-2013年,研究区生态风险程度总体上呈现降低的趋势,低及较低风险区域集中分布在研究区以耕地为主的绿洲区域,而较高及高风险区域主要分布在山地、沙地等未利用地广布及盐碱化严重的景观类型单一又无法进行人类活动的区域。(3)经与线性回归分析预测模型的比较,采用模型拟合度达到0.9886的BP神经网络方法建立渭干河-库车河三角洲绿洲生态风险预警模型。通过预警模型得到,2019年渭干河-库车河三角洲绿洲生态风险与前期实际趋势保持一致,总体呈现降低的趋势,但绿洲外围特别是盐碱地、其他用地分布较为集中的区域生态环境仍比较恶劣,生态风险较高,需要针对此区域进行有效的治理与改善,提高研究区整体的生态环境水平。对生态系统极不稳定的渭干河-库车河三角洲绿洲开展生态风险研究,能促进当地人民对生态风险的认识,帮助政府职能部分对生态风险进行有效的管理,对区域土地合理的开发与可持续性利用及生态环境的保护起到积极的作用。
[Abstract]:With the rapid increase of population and people are not the rational allocation of resources, adjustment of the ecosystem itself lead to declining living environment where people are more vulnerable, bear the increased risk. Based on the selected typical alluvial diluvial plain northwest of the Weigan River Kuche River Delta Oasis as a study area the application of remote sensing, method and technology, combined with remote sensing images, field survey data and DEM the study area map, land use map, social economic statistics data, ecological risk assessment and early warning. At the time of selection of remote sensing image in summer and autumn in the region 1989200120072013 years of land use / cover the landscape by supervised classification the extraction, based on which the dynamic changes of the landscape pattern analysis and forecast, and then to the ecological risk index was constructed by ecological landscape pattern index in the study area To assess the risk of the final choice of Ecological Warning Index, BP neural network algorithm is used to construct the early warning model of ecological risk in the study area, the main conclusions are as follows: (1) 1989-2013 in Weigan River Kuche River delta oasis landscape types did not change, but the change of the area and the proportion of each type of landscape is larger the overall performance for the expansion of the oasis area trend, cultivated land area in 2013 reached 41.74 * 104 hm2. conversion between cultivated land and grassland is more obvious, the maximum reached 14.32 * 104 hm2. CA-Markov model is used to predict the distribution of oasis landscape in Weigan River Kuche River Delta in 2019, the overall trend is still in oasis area expansion, reach 55.48 * 104hm2. on the performance of landscape was decreased with the increase of woodland and grassland and saline land. (2) 1989-2013 in the study area to reduce the degree of landscape fragmentation, degree of aggregation increased between patches, The biggest advantage of increasing landscape connectivity, the number and area proportion of each patch type toward the unbalanced development of.1989 years -2013 years, the degree of ecological risk in the study area generally showed a decreasing trend in oasis area and low risk area of low concentrated mainly on the cultivated land in the study area, while the high and high risk areas are mainly distributed in the mountain, sandy land and unused land salinization and widespread landscape types and can not be a single serious area of human activity. (3) by linear regression analysis and prediction model, the model fit to the BP neural network method to establish 0.9886 Weiganhe oasis ecological risk warning model of Kuche River Delta. Get through the early warning model, 2019 Weigan River Kuche River Delta Oasis Ecological Risk and the actual trend is consistent, overall showed a decreasing trend, but the oasis especially saline And other land concentrated regional ecological environment is still relatively poor, high ecological risk, need for this regional governance and effectively improve the ecological environment, improve the overall level of the study area. The extremely unstable on the ecosystem of ecological risk in Weigan River Kuche River Delta Oasis, can promote the local people understanding of ecological risk, to help government departments to carry on the effective management of regional land ecological risk, reasonable exploitation and sustainable utilization and protection of ecological environment has played a positive role.

【学位授予单位】：新疆师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X826

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