ISWC OpenIR  > 水保所知识产出(1956---)
延河流域土地利用景观格局 变化对径流输沙的影响
花东文
Subtype硕士
Thesis Advisor温仲明
2015-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword延河流域 土地利用景观格局 水沙变化 恢复阶段
Abstract

退耕还林(草)政策在黄土高原地区实施已逾 20 载,流域内土地利用景观
格局和径流泥沙发生显著变化,针对这一现象,本论文以延河流域为研究区,基
于甘谷驿水文站的长期实测水沙数据(1970-2010),结合四期遥感影像资料(1978
年、1990 年、2000 年、2010 年),采用 GIS、RS 和野外人工模拟降雨等技术手
段,运用景观生态学、数理统计和定性定量相结合的分析方法。在流域尺度上,
对延河流域的土地利用景观格局和径流泥沙变化特征进行分析总结,并建立景观
格局指数和径流泥沙指标之间的关系;同时,在坡面尺度上,研究不同恢复阶段
的人工刺槐林地、人工柠条林地和自然恢复草地的坡面产流产沙特征及减流减沙
效益,为解释流域尺度上土地利用景观格局变化对径流泥沙的影响提供理论基础。
研究取得的主要结论如下:
(1)经过多年的生态建设和流域综合治理,尤其是退耕还林(草)工程的
实施,延河流域的土地利用景观格局发生了显著变化。在斑块水平上,耕地和草
地的破碎度较高,斑块形状也较复杂,林地、建设用地和水域斑块分布趋于集中
化,破碎度较小,形状较为简单;在景观水平上,以耕地为主导的土地利用景观
格局已不复存在,而以林地和草地为主导的新的土地利用景观格局正在形成,景
观格局大致经历了“耕地主导-相对平衡-林草主导”的变化过程,向集中化和简
单化的方向发展,由于林草植被的减蚀作用,以林草为主导的景观格局有利于生
态环境的改善。
(2)延河近 40 年的水沙量均呈下降趋势,输沙量的下降幅度高于径流量,
Mann-Kendall 趋势检验表明, 2005 年为水沙发生突变的年份。其变化过程大致
经历了三个阶段,1970-1986 年为水沙波动期,1987-1996 年为丰水丰沙期,
1997-2010 年为枯水枯沙期。造成这种变化的主要原因不是降雨,而与流域内植
被恢复引起土地利用的阶段性变化有关。
(3)在流域尺度上,以耕林草为主导的土地利用景观格局与水沙变化关系
密切。在景观类型水平上,延河流域耕地斑块的分离度指数、林地斑块的连通度和草地斑块的斑块个数对流域的径流过程影响较大,耕地斑块的边缘密度、林地
斑块的斑块所占景观面积比、草地斑块的散布与并列指数与流域的输沙过程关系
密切。回归方程表明林地和草地斑块的面积越大和连通性越高,分布越集中;耕
地受人类活动的扰动越弱,分布越分散,则流域内的水土流失程度越弱,反之则
越强。在景观水平上,延河流域景观格局的斑块个数、平均斑块面积、多样性指
数和聚集度指数共同影响着流域的径流和输沙过程。回归方程表明景观的破碎化
程度越弱,多样性越丰富,分布越集中,流域的径流输沙量越小。
(4) 在坡面尺度上,植被恢复年限是影响延河流域自然恢复草地、人工柠
条林地和人工刺槐林地产流产沙的一个重要因素。同一植被恢复方式,在不同恢
复阶段的径流率和产沙强度变化规律各不相同。随恢复年限的增加,自然恢复草
地和人工柠条林地的径流率和产沙强度都减小,而人工刺槐林地则表现出径流率
差异不显著,产沙强度增大,主要是由于人工刺槐林地的郁闭度较高和树木高度
增加所致。各恢复阶段的累积径流量(Q W )、累积产沙量(Q S )和降雨历时之间
均存在较好的二次函数关系,而累计产沙量和累计产流量之间的相互关系可通过
幂函数来反应。
(5) 对于不同恢复阶段的自然恢复草地、人工柠条林地和人工刺槐林地,
其减沙效益均大于减流效益,这也很好的解释了流域尺度上泥沙减少幅度大于径
流的问题。人工刺槐林地的减流减沙效益最为突出,处在一个很高的水平,具有
蓄水减沙的水土保持功效,自然恢复草地和人工柠条林地的减水减沙效益都随恢
复年限的增加而增加,具有直接拦沙的水土保持功效。同时,处在恢复初期(0~8
年)的自然恢复草地和人工柠条林地,生态功能仍然比较脆弱,以及恢复后期(16
年以上)的人工刺槐林地,如果地表植被遭到破坏,仍然是暴雨条件下产沙的主
要来源之一,因此,在植被恢复重建过程中,要做好封育、禁牧等保护措施。
关键词:延河流域,土地利用景观格局,水沙变化,恢复阶段

Other Abstract

Since the implementation of the project of returning cropland to woodland or
grassland in the Loess Plateau in 1999, the land-use landscape pattern, runoff and
sediment has changed significantly. This study take Yanhe River Basin as a case study
area. According to the long-term (1970-2010) hydrological data measured at Ganguyi
hydrological station and four periods of land use data (1978, 1990, 2000, 2010), the
change in land-use landscape pattern, and runoff and sediment were analyzed in
Yanhe River Basin. The relationship between landscape index and runoff and
sediment were also studied on basin scale, using the GIS and RS techniques, through
the simulated rainfall experiments and combing the methods of landscape ecology,
qualitative, quantitative and mathematical statistics analysis. The runoff and sediment
characteristics and benefit of natural grassland, artificial caragana korshinskii land
and artificial robinia pseudoacacia forestland with different restoration stages on slops
were analyzed, which provided the theoretical foundation for explaining the influence
of land-use landscape pattern on runoff and sediment on basin scale. The main
conclusions are as follows:
(1) The landscape pattern of Yanhe River Basin has changed significantly after
years of ecological construction and comprehensive management of watershed,
especially the implementation of the project of conversing cropland to woodland or
grassland. At the patch level, the fragmentation of grassland and cultivated land were
higher than other landscape types and their patch shapes were more complex. At the
landscape level, the landscape pattern dominated by cultivated landchanged to the
new landscape pattern dominated by forest land and grassland. The landscape pattern  dominated by forest land and grassland was beneficial for the improvement of the
ecological environment because of their role in erosion reduction.
(2) In the past 40 years, the annual change of runoff and sediment of Yanhe River
Basin showed a downward trend, and the change rate of sediment was higher than
runoff. Mann-Kendall non parametric statistical tests showed that the turning point of
runoff and sediment was the year 2005. The change of runoff and sediment
experienced three obvious periods. The main cause is not precipitation, but related
with the changes in land-use caused by vegetation restoration in Yanhe River Basin.
(3) The relations between landscape pattern dominated by cultivated land, forest
land and grassland and changes of runoff and sediment were very significant on
watershed scale. At the patch level, the SPLIT index of cultivated land, the
CONNECT index of forest land and the NP index of grassland played an important
role in the process of runoff, However, the ED index of cultivated land, the PLAND
index of forest land and the IJI index of grassland were closely related to the process
of sediment. The regression equations indicated that the soil and water erosion was
lighter when the area of forestland and grassland was greater and the connectivity was
higher and the distribution of cultivated land was more dispersed. At the landscape
level, the runoff and sediment yield of Yanhe River Basin showed a negative
correlation with NP index, AI index and showed a positive correlation with
AREA-MN index and SHID index. The regression equations showed that the runoff
and sediment discharge was less when the landscape fragmentation was lighter and
the landscape diversity was richer and the landscape distribution was more
concentrated.
(4) The restoration year was an important factor that influenced the runoff and
sediment yield of natural grassland, artificial caragana korshinskii and artificial
robinia pseudoacacia forestland on slop in Yanhe River Basin. Under the same
vegetation restoration mode, the variation of runoff rate and sediment yield intensity
under vegetation at different restoration stages is quite different. With the increase of
restoration years, the runoff rate and sediment yield intensity of natural grassland and
artificial caragana korshinskii land decreased, but the changes in runoff rate of
artificial robinia pseudoacacia forestland was not significant, and the sediment yield  intensity of artificial robinia pseudoacacia forestland increased because of the increase
of canopy density and tree height. There were good quadratic functions between
accumulated sediment, total runoff and rainfall time on different restoration stage. The
relationship between accumulated sediment and the total runoff can response by
power function.
(5) The sediment reductions of different restoration stages were all higher than
the runoff reductions, which answered the question why the decreasing rate of
sediment was higher than the runoff on watershed scale. The effect of artificial robinia
pseudoacacia forestland on runoff and sediment reduction was the most outstanding.
The benefit of natural grassland and artificial caragana korshinskii woodland
increased with the increase of restoration years. The ecological functions of natural
grassland and artificial caragana korshinskii woodland were relatively small in the
early recovery stage (0-8 years). If the surface vegetation of artificial robinia
pseudoacacia forestland was destroyed in the later recovery stage (more than 16
years), it was still one of the main source of sediment yield when encountered a heavy
rainfall. Therefore, we must complete fencing and prohibiting grazing measures in the
process of vegetation restoration.
Key words: Yanhe River watershed, land-use landscape pattern, runoff and sediment
change, restoration stage

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/9034
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
花东文. 延河流域土地利用景观格局 变化对径流输沙的影响[D]. 北京. 中国科学院研究生院,2015.
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