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题名: 黑河下游植被覆盖的时空变化特征与生态需水研究
作者: 沈亲1
学位类别: 博士后
答辩日期: 2017-07
授予单位: 中国科学院大学
授予地点: 北京
导师: 吕一河
关键词: 径流 ; NDVI ; River flow, NDVI,Groundwater, Desert riparian forest, SEBS, Heihe River Basin ; 地下水 ; 河岸林 ; SEBS ; 黑河流域
学位专业: 环境科学与工程
中文摘要: 水资源对干旱内陆河流域绿洲生态系统的稳定发挥了重要作用,不合理的水 资源开发利用会导致一系列生态环境问题,并加剧流域中、下游间的用水矛盾。 水文和气候条件是影响流域植被覆盖的关键因子,研究植被时空动态变化规律与 水文气象因子的关系,科学估算天然绿洲生态需水量,可以加深对生态水文过程 机理的理解,并可为流域水资源合理分配与绿洲生态系统的稳定、可持续发展提 供科学依据。以往研究在植被变化与水文气象因子关系的时空动态特征和生态需 水的科学计算与时空变化规律等方面相对不足,需要进一步研究。 本文以黑河下游狼心山水文站以下区域为研究区,综合运用地面和遥感监测、 统计分析和模型模拟等方法,分析了研究区降水气温、径流、地下水埋深等气象 水文因子和 NDVI在 2000-2015年的变化规律,在流域和栅格尺度建立了 NDVI 变化与气象水文因子的定量关系。在对 SEBS(Surface Energy Balance System) 模型进行率定和验证基础上,估算了东、西河沿岸,额济纳绿洲和东居延海 2014- 2015年的生态需水量,分析了其时空变化规律。主要结论如下: (1)NDVI呈逐年增加趋势,且增加显著(p < 0.01),年平均 NDVI值的变 化率为 0.0007。NDVI的空间变化趋势表明:NDVI在东河上游和下游,西河中 游与额济纳绿洲等区域呈增加趋势,显著增加区域和降低区域面积分别占总面积 的 25.6%和 2.9%。NDVI增加显著的区域年变化率为 0.0002-0.0505 yr-1,平均值 为 0.003 yr-1。降低显著的区域年变化率为-0.0157--0.0002 yr-1,平均值为-0.002yr-1。河道径流对 NDVI的显著影响范围约为 2 km。 (2)流域尺度上,NDVI与降水量和温度的关系都不显著,研究区和东居延 海 NDVI与 1年前径流呈显著线性相关(p < 0.05)。栅格尺度上,NDVI与温度 关系显著的区域分布比较均匀,NDVI与径流关系显著的区域主要分布在东、西 河沿岸以及西居延海附近。NDVI与降水、温度和径流显著正相关的区域占到研 究区的 0.65%、17.40%和 7.14%。地下水埋深随河道径流的增加而线性减少(p < 0.05)。NDVI与地下水埋深在 1.8-3.5 m,植被覆盖较好。 (3)SEBS模型估算自然绿洲需水量具有较高的精度。........
英文摘要: Water resources play a critical role in the development of the natural oases ecosystems in arid inland river basin. Due to the unreasonable utilization, water resource scarcity has caused deterioration of the ecology and environment. The contradiction between middle and downstream area has become increasingly prominent. The water resources and climate change have caused the changes of hydrological processes. The knowledge of the influences of hydro-climatic factors on vegetation variations is useful for understanding the hydrological processes. Previous studies about the spatio-temporal variations of vegetation cover and hydro-climatic factors and the scientific calculation of ecological water requirement are relatively insufficient, which need further study. The study area is located below the Langxinshan hydrological station in the lower Heihe River Baisn. The variations of hydro-climatic factors including precipitation, temperature, river flow, water table depth and NDVI from 2000 to 2015 were analyzed. The quantitative relationships between NDVI and hydro-climatic factors were established at the basin and grid scale. Based on the analysis and verification of SEBS (Surface Energy Balance System) model, the ecological water requirements of East River, West River, Ejina Oasis and East Juyan Lake in 2014-2015 were estimated, and temporal and spatial variations of ecological water requirements of the study area were analyzed. The conclusions were as follows: (1) The monthly NDVI showed obviously seasonal trend, the highest value occurred in July and August, while the lowest value happened in January and December. The mean yearly NDVI increased significantly (0.0007 yr-1 , p < 0.01), with the mean value of 0.08. The spatial pattern of NDVI change showed that the greening trend was evident in the study area. Both the upper and down reach of the East river and middle reach of the West river showed an increasing trend of NDVI, especially around the EJL. However, a decreasing trend of NDVI was found along both the upper and middle reach of the West river, and middle and lower reach of the East river as well as the heart of Ejina Oasis. The areas with a significantly increasing and decreasing trend of NDVI accounted for 25.6% and 2.9% of the study area, respectively (p < 0.05). The mean changing slopes of NDVI were 0.003 yr-1and -0.002 yr-1for the significantly increasing and decreasing areas with the range of 0.0002 - 0.0505 yr-1and -0.0157 - -0.0002 yr-1 , respectively. The mean NDVI along the river decreased with increasing distance from the river bank, and the vegetation affected significantly by the river flow mainly concentrated within 2 km distance from the river bank. (2) At basin scale, the growing season NDVI was insignificantly correlated with both precipitation and temperature, whereas it increased significantly with the antecedent one year river flow, and could be fitted well with a linear regression at the Ejina oasis and EJL. The lag-time effect of the river flow on the vegetation cover was 1 year. At the pixel scale, there was only 0.65% of the study area showing significantly positive relationship between NDVI and precipitation. The area of the significantly positive relationship between NDVI and temperature accounted for about 17.40% of the study area. NDVI was significantly positive with runoff in about 7.14% of the study area, which was mainly distributed along the East and West River and EJL. The higher NDVI was corresponding to water table depth ranging between 1.8 m and 3.5 m. (3) SEBS could be used to estaimte the ecological water requirement of nature oasis in the study area. The total ecological water requirement of the study area was 6.54×10 8 m3 and 7.56×10 8 m 3 in 2014 and 2015, respectively, and the growing season ecological water requirement accounted for 83.2% and 82.6% of annual value in 2014 and 2015, respectively. The cumulative ecological water requirement could be described by an exponential function. The distance where the cumulative ecological water requirement away from the river bank accounting for 90% of the total value was approximately 3.75 km and 2.75 km for the East river and West river, respectively.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38688
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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作者单位: 1.中国科学院生态环境研究中心
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