【作者】 崔雪晴；

【导师】 刘世荣；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2013， 博士

【摘要】 在大尺度森林流域中土地覆盖的变化和区域气候变化是目前研究公认的两大影响生态水文过程和水量平衡关系的驱动因子。杂谷脑流域位于长江上游第一大支流岷江流域的上游，地处四川平原向青藏高原过渡的地带，对气候变化十分敏感。流域内植被垂直地带性分布强，上世纪50年代森林大规模皆伐和随后的植被恢复建设对流域的生态水循环过程产生了较大影响。本研究以岷江上游杂谷脑流域为研究对象，调查整理了杂谷脑流域的地形、植被、气象、土壤数据集和地面观测资料，采用统计分析与分布式生态水文模型运用相结合的方法，对1953-2011年杂谷脑流域内不同时段上发生的土地覆盖变化、气候变化、水量平衡变化以及三者之间的关系进行了探讨，旨在定量评价杂谷脑流域内水循环过程的变化趋势，以及流域生态水文过程和水量平衡对土地覆盖变化和气候变化的响应。以期为流域水资源与水环境的可持续性综合管理提供决策依据和参考。主要研究成果如下：(1).利用杂谷脑水文站1958-2005年段的水文数据，以及周围气象站1958-2005年的气候数据形成的面气候数据分析表明，从1958-2005年的48年间杂谷脑流域年平均径流量和丰水期径流没有显著变化（P>0.05,tau=0.126,tau=0.067）。枯水期径流呈先下降（1976-1981年）后上升的显著趋势（P<0.05, tau=0.231）。对降水-径流双累积线做检验发现年径流量在1969年后出现上升趋势（P<0.05,tau=0.134），1991年又出现多次突变。丰水期径流在1965和1998年出现两个变点呈先上升再下降的趋势（P<0.05,tau=0.084.tau=-1.361）。枯水径流在1965年以后呈下降趋势（P <0.05, tau=-0.051）。(2).基于对杂谷脑流域生态水文要素和背景知识的调查和了解，首先确定了模型不同土壤类型和植被类型的属性输入参数。通过率定和检验，表明SWAT模型能较好的模拟杂谷脑流域的水文过程，模拟径流量与出口实测径流量吻合较好，日尺度模拟径流与实测径流R2达到了0.78，效率系数达到了0.51，月尺度模拟径流与实测径流R2达到了0.89，效率系数达到了0.81。月尺度蒸散与MODIS蒸散的拟合程度R2达到了0.90，E达到了0.80。(3).杂谷脑流域1990-1999年间蒸散和产流分别占降水量的39.24%和60.26%，其中蒸腾、冠层截留、土壤蒸发分别占蒸散的41.78%，15.75%和42.47%，地表径流、壤中流和基流分别占产流量的33.30%，54.77%和11.32%。流域内森林的产流量分别比高山草甸、农田和灌丛低166.82mm，126.15mm，155.03mm，蒸散分别比高山草甸、农田和灌丛高128.61mm，88.60mm，103.21mm。不同森林中，人工针叶林的蒸散量比针叶林和混交林高（87.13mm，11mm），而地表径流量又分别比针叶林混交林和阔叶林高51.76mm，37.09mm和68.09mm。表明人工林对于水分的蒸散大且地表径流强，易发生水土流失，而针叶林蒸散小，产流量大，与亚高山地区森林水源涵养的经营方向吻合，因此要加强对针叶林的保护，在森林种植方面建议采用针阔混交的方式，避免单一种植同种针叶林，以有效平衡地表径流占产流量的比例。从几对海拔和面积相似的子流域看，森林比例高的子流域其地表径流显著低于其他子流域，但径流系数并没有地表径流的差距显著。草甸比例越高的子流域地表径流越大，其影响要大于不同森林类型配比的影响。(4).以海拔从低到高为顺序设置了8个皆伐梯度情景（5%-40%），结果表明流域径流量随森林皆伐面积升高总体呈增大趋势，但是有较大空间异质性，在海拔3221m以下区域，皆伐每面积上升5%，蒸散量升高1.73mm，土壤蒸发量升高5.90mm,径流降低-0.7mm；而海拔3221m以上，皆伐每面积上升5%，蒸散量降低2.86mm，土壤蒸发量上升2.18mm,径流增加2.0mm。根据森林恢复历史设计的情景模拟表明人工林恢复每10年径流/降水降低1.43%，蒸散/降水升高2.67%。(5).杂谷脑流域水文要素对降水的响应强于温度，1970-2011年杂谷脑流域温度出现了显著增加趋势（P<0.05），降水量没有显著变化，而蒸散、地表径流和出口径流量也没有显著变化（P>0.1）。部分子流域降水出现了显著上升趋势，降水变化对蒸散的影响最显著，其次是地表径流，径流量对降水变化的响应最小。在降水变化情境下总产流量对降水增强的响应更大，而蒸散对降水减弱的响应更强。降水每增加10%产流量增加7.9%，蒸散量增加0.8%，；降水减少时产流量减少4.2%，蒸散量减少1.3%。温度增加对产流量的影响率比温度减少要大，而土壤蒸发和冠层截留随温度减少的变化幅度更大，蒸散对增温和减温的响应幅度相差很小。更多还原

【Abstract】 Land cover change and climate change has been firmly believed as the key impact of watercycle and water balance in forest watershed with large scale.The Zagunao Riveristhe upperstream of Minjiang River which is the largest tributary of Yangtze River. The watershed lies onthe transition zone of Qinghai-Tibet Plateau to Sichuan basin where climate change impactsignificantly on local ecosystem.The vegetation in Zagunao watershed is relatively simple,which has almost been changed by massive forest harvesting and forest recovery. As a hypothesis,we assumed that climate change and massive forest variation has influence regional water cycleand water balance andquantified and discussed the whole relation and process in this paper basedon both statistic and modeling way in both temporal and spatial perspective. The main resultsand conclusions are as follows:(1). We analyzed the hydrological regime in Zagunao watershed during1958-2005basedon the observed data of6weather stations and the hydrology station on the outlet of Zagunaowatershed. The results showed that, the annual precipitation, and annual runoff and runoff in wetseason had no significant tendency during1985-2005(P>0.05, tau=0.05,0.126,0.067), whilerunoff in dry season had a significant decrease (P<0.05, tau=0.23).Beaks have been detectedwith the double mass curve of runoff and precipitation in Zagunao river during1958-2005basedon Mann-Kendall test. Annual runoff significantly increased after1969(P<0.05, tau=0.13) andvariated a lot after1991respectively. Runoff in wet season significantly increased after1965(P<0.05, tau=0.084) and decreased after1998respectively (P<0.05, tau=-1.361). Furthermore,the breaking time was quite coincide with forest variation period.(2). The best substream quantity in Zagunao watershed was27(R2=0.72and E=0.33). Thenthe parameters of vegetation and soil type was determined based on investigation and earlypapers. SWAT model performed well in Zagunao watershed after complex parameterization and calibration: for monthly flow, daily flow, and ET, the R2was0.89,0.78and0.90respectively andE was0.81,0.51and0.80respectively.(3). The percentage of ET and water yield to precipitation was39.24%and60.26%respectively, transpiration/ET, interception/ET and evaporation/ET was41.78%，15.75%and42.47%respectively, and surface runoff/runoff, lateral flow/runoff and base flow/runoff was33.30%，54.77%and11.32%respectively. Water yield in forest was higher than alpine meadow,crop, and shrub significantly (P<0.05,166.82mm，126.15mm，155.03mm), while ET was lowerthan alpine meadow, crop, and shrub significantly (P<0.05,128.61mm，88.60mm，103.21mm).ET of plantation was higher than coniferous forest and mixed forest (87.13mm，11mm), whilethe sueface runoff of plantation was also higher than coniferous forest, mixed forest andbroadleaved forest (51.76mm，37.09mm and68.09mm) which indicated that coniferous forestwas better in conserving water, while plantation had both disadvantage in higher ET and surfacerunoff.(4). The runoff increased with clear cutting area in our clear cutting scenario (5%-40%)with spatial heterogeneity: ET increased1.73mm once clearcuting area widen by5%whenaltitude was blow3221m and decreased2.86above3221m. After harvesting, Water yieldefficiency decreasedas the stand age increaseduring the tenth to thefortieth year. Meanwhile, theET efficiency,transpiration efficiencyincreased by2.67%and1.56%, and the water yieldefficiency and evaporation efficiency decreased by1.43%and1.31%every ten year as forestgrow.(5). Precipitation had a stronger influnce than temperature on water cycle in Zagunaowatershed. Water yield increased by7.9%,168.7%, and ET increased by0.8%once precipitationincreased by10%,20%,30%. On the contrast, water yield decreased by4.2%, and ET decreasedby1.3%once precipitation decreased by10%. Meawhile, Increasing of temperature had a largerinflunce on water yield than decreasing while few difference was there on the impact to ET.更多还原