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高寒沼泽湿地退化对长江源流域夏汛期径流的影响
李佳
学位类型博士
导师罗毅 ; 包安明
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业自然地理学
关键词高寒沼泽湿地 长江源流域 夏汛期径流 Swat
摘要高寒沼泽湿地在长江源流域由于气候变化的原因退化显著。高寒沼泽湿地在长江源流域具有重要的水源涵养和径流调节的功能,它的退化会对长江源径流特别是夏汛期径流过程和洪峰特征因子引起变化。认识高寒沼泽湿地退化对长江源流域夏汛期的径流过程的影响,有利于科学认识长江源地区的气候与水文相互作用机制。因此,本文不同于以往的研究只是点观测研究高寒沼泽湿地退化对长江源水文过程的影响,利用发展的具有高寒沼泽湿地模块分布式水文模型(SWAT-ASW),结合高寒沼泽湿地在流域的退化情况,探讨了高寒沼泽湿地对高寒流域(长江源)的夏汛期径流的影响,并分析湿地的涵养水源和调流条件功能。取得了以下结论: 1)高寒沼泽湿地面积在长江源区1975-2004年30年间退化严重,达到了28%。其中1990-2004年间退化程度比1975-1990年间更显著。面积退化的高寒沼泽湿地植被NPP下降趋势高于面积未退化的。并且在同等降水条件下,面积未退化的高寒沼泽湿地生态系统稳定性好于面积退化的。湿地地表蓄水量分别在3个时期(1975年,1990年,2004年)为13.58×108m3,12.44×108m3和9.75×108m3。分别占流域平均径流的1.06%,0.91%和0.73%。 2)SWAT模型在直门达模拟径流结果是“满意” (NSE=0.63和R2=0.58),在沱沱河站日径流模拟基本刚刚达到“满意”(NSE=0.51和R2=0.57),模拟的结果说明SWAT基本能够反映长江源流域的径流过程。此外,在春汛期径流也存在不足的问题。 3)SWAT-ASW模型具有滨河湿地和隔离湿地的水文循环过程,能够很好的反映长江源流域夏汛期(7.15-9.30)径流的过程。SWAT-ASW模型比SWAT模型和SWAT-HEW模型在夏汛期径流的模拟结果更好(NSE = 0.65和R2=0.64)。此外,该模型能够从模型机理角度很好的解释高寒沼泽湿地在长江源流域的涵养水源和调节洪峰功能。 4)高寒沼泽湿地的退化,会引起夏汛期径流的减少。 当高寒沼泽湿地退化10%和退化30%,日平均径流分别下降了6.8%和10.7%。这说明了湿地退化越严重,径流减少程度越大。同样的情况发生在高寒沼泽湿地退化对地表径流和壤中流的影响。当高寒沼泽湿地退化10%和退化30%,地表径流分别减少16.4%和29.7%,壤中流分别减少9.6%和14.9%。而高寒沼泽湿地退化对地下水和ET的影响正好相反,当高寒沼泽湿地退化10%和退化30%,地下水分别增加7.6%和14.1%,ET分别增加1.6%和3.2%。此外,高寒沼泽湿地退化越多,会造成夏汛期稀疏较大径流发生频率增加和中等径流发生频率减少。夏汛期直门达降水径流系数随着高寒沼泽湿地退化加剧而减少,而沱沱河降水径流系数则增大。夏汛期洪峰因子特征分析结果表明,随着高寒沼泽湿地的退化,直门达和沱沱河的洪峰次数增加,而持续时间和上升时间都缩短了。
其他摘要Alpine swamp wetland (ASW) decreased dramatically in Headwater region of Yangtze River (HYR) during the last 30 years due to the climate change. Functions of maintaining water resources and adjusting runoff balance were hold by ASW. Runoff process in summer rainfall season could be changed as the decrease of ASW. It helps us to understand the relationship between climate and hydrology in HYR by detecting how ASW affect runoff process. Therefore, the effect of ASW on runoff process in summer rainfall season was studied by a developed SWAT-ASW model. The main findings were below: 1)28% of ASW areas were decreased in last 30 years (1975-2004) in HYR. The ASW declined more in the period of 1990-2004 than that in period of 1975-1990. Net Primary Production (NPP) shortened faster in the decreasing areas of ASW than that in non-decreasing areas of ASW. The ecosystem stability of non-decreasing areas of ASW was better than that of decreasing areas of ASW under same precipitation density. Surface water volumes were hold by wetland depths. Surface water volumes were 13.58×108m3 ,12.44×108m3 and 9.75×108m3 in the years of 1975,1990 and 2004, which was about 1.06%,0.91% and 0.73% of total runoff volumes. 2) Result of SWAT model runoff simulation at ZMD was “satisfied” (NSE=0.63 and R2=0.58). While it was “satisfied” in TTH (NSE=0.51 and R2=0.57). Therefore, SWAT model was satisfied about runoff simulation in HYR. In addition, runoff process was underestimated in spring rainfall season by SWAT. 3) The riparian swamp wetland water cycle and geographic isolated swamp wetland water cycle were both introduced to SWAT-ASW model in this study. The new SWAT-ASW modeled the runoff process much better than SWAT and SWAT-HEW in rainfall season (7.15-9.30) (NSE = 0.65, R2=0.64). The mechanism of runoff process during rainfall season was explained clearly by SWAT-ASW in HYR. 4) The runoff was shortened in summer rainfall season as the ASW decrease. When ASW decrease 10% and decrease 30%, runoff decreased 6.8% and 10.7%. The more ASW decrease, the more runoff decrease. The same situation was in surface runoff and lateral runoff. When ASW decrease 10% and decrease 30%, surface runoff decreased 16.4% and 29.7%, lateral flow decreased 9.6% and 14.9%. However, to groundwater and ET, the more ASW decrease with the more increase of them. When ASW decrease 10% and decrease 30%, groundwater increased 7.6% and 14.1%, ET increased 1.6%和3.2%. In addition, bare big flood happened more and middle flood decreased under the ASW decrease from period 1975-1990 to period 1990-2004. Rainfall-runoff coefficient in ZMD decreased, while it increased in TTH under the ASW decrease. The summer flood events frequencies were both increased in ZMD and TTH, flood duration and rising time were both shortened by ASW decrease.
学科领域自然地理学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14628
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
李佳. 高寒沼泽湿地退化对长江源流域夏汛期径流的影响[D]. 北京. 中国科学院大学,2015.
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