泾河干流上游森林覆盖率水文影响的年份和月份差异
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摘要
定量评价和预测西北干旱地区森林面积增加的水文影响,为基于水资源承载力的植被恢复与管理提供科学依据。以黄土高原泾河干流上游流域为例,制定森林植被恢复的多种情景,利用率定过的SWIM水文模型和1997—2003年间的气象数据,模拟森林覆盖率变化对蒸散和径流的影响。研究表明:1)草地变森林后,随森林覆盖率增加,年均总蒸散呈明显线性增加,年均径流则呈明显线性减少。在本研究范围内(森林覆盖率增加0~18.13%),森林覆盖率每增加10%平均导致年均总蒸散增加8.93 mm,年均径流减少6.04 mm;2)森林覆盖率变化对年总蒸散的影响具有年际差异,受年降水量影响,流域森林覆盖率增加10%时,对应的年蒸散增量分别为枯水年(10.1 mm)>平水年(8.6 mm)>丰水年(8.5 mm),而对应的年径流减少量分别为枯水年(9.0 mm)>平水年(5.6mm)>丰水年(5.1 mm);3)森林覆盖率增加导致的蒸散增大和径流减少还具有月份差异,其中蒸散在春季(3—5月)和初夏(6月)增大,而夏季中期(7、8月)至秋季中期(9、10月)则减少,在秋末(11月)和冬季(12、1、2月)则变化不明显;径流在春季和夏季明显减少,而秋季中期(9、10月)则呈增加趋势,冬季变化不明显。总之,在该流域增加森林覆盖率会导致年蒸散增加和年径流减少,这种变化在枯水年明显大于平水年和丰水年;森林覆盖率变化对蒸散和径流的影响还存在月份差异,表现为春夏季影响大于秋冬季;增加森林具有一定增加基流和枯水期径流的调节作用。
[Background]Many activities of vegetation restoration have been implemented in the Loess Plateau of northwest China since the 1950 s in order to improve the ecological environment.These have led to a significant increase in the forest coverage,which is being and going to be enhanced in the futuredue to its unique role in active responses to the global climate change.However,a series of recent studies confirmed that the increase of forest coverage caused a significant runoff reduction and concequently endangered the safe and sustainable usage of water resources.Therefore,based on the forest-water relationship a quantitative evaluation of regional hydrology on the impact of afforestation is urgent and benificial to the vegetation restoration and watershed management.[Methods]Collecting the measured meteorological data during the period of 1997—2003 in the upper reaches of Jinghe River in the Loess Plateau of northwest China,we used the calibrated eco-hydrological model of SWIM to evaluate the hydrological impacts of forest coverage change on the the evapotranspiration and runoff.The evaluation was based on simulation results from many scenarios of forest/vegetation restoration.[Results]1) Under the scenarios of converting grassland to forestland,the yearly evapotranspiration increased and runoff decreased linearly with the rising forest coverage.Within the studied period of forest coverage increase(0-18.13%),the changing rate corresponding to an increase of forest area of 10% of watershed area was 8.93 mm increase for the yearly evapotranspiration,but a 6.04 mm decrease of the yearly runoff.2)The impact on yearly evapotranspiration by forest coverage change showed a yearly difference because of the difference in annual precipitation.A 10% increase of forest coverage led to an increase of yearly evapotranspiration of 10.1 mm in dry years,8.6 mm in normal years,and 8.5 mm in wet years; but a decrease of yearly runoff of 9.0 mm in dry years,5.6 mm in normal ears,and 5.1 mm in wet years,respectively.3) There was also a monthly difference in the responces of yearly evapotranspiration and water yield to the increase of forest coverage.The evapotranspiration was increased in the Spring(March-May) and the early Summer(June),decreased in the period from the mid Summer(July and August) to the mid Autumn(September and Octomber),and not significally changed in the late Autumn(November) and Winter(December,January and Februry); whereas the runoff decreased in the Spring and Summer,but increased in the mid Autumn(September,Octomber),and not obviously changed in Winter.[Conclusions] In summary,the increase of forest coverage in the studied watershed led to an increase of yearly evapotranspiration and a decrease of yearly runoff.These hydrological impacts were more significant in dry years than in normal years and wet years.The hydological impacts of forest coverage change on the evapotranspiration and runoff diffred among the months,much significantly in the Spring and Summer than in the Autumn and Winter.
[Background]Many activities of vegetation restoration have been implemented in the Loess Plateau of northwest China since the 1950 s in order to improve the ecological environment.These have led to a significant increase in the forest coverage,which is being and going to be enhanced in the futuredue to its unique role in active responses to the global climate change.However,a series of recent studies confirmed that the increase of forest coverage caused a significant runoff reduction and concequently endangered the safe and sustainable usage of water resources.Therefore,based on the forest-water relationship a quantitative evaluation of regional hydrology on the impact of afforestation is urgent and benificial to the vegetation restoration and watershed management.[Methods]Collecting the measured meteorological data during the period of 1997—2003 in the upper reaches of Jinghe River in the Loess Plateau of northwest China,we used the calibrated eco-hydrological model of SWIM to evaluate the hydrological impacts of forest coverage change on the the evapotranspiration and runoff.The evaluation was based on simulation results from many scenarios of forest/vegetation restoration.[Results]1) Under the scenarios of converting grassland to forestland,the yearly evapotranspiration increased and runoff decreased linearly with the rising forest coverage.Within the studied period of forest coverage increase(0-18.13%),the changing rate corresponding to an increase of forest area of 10% of watershed area was 8.93 mm increase for the yearly evapotranspiration,but a 6.04 mm decrease of the yearly runoff.2)The impact on yearly evapotranspiration by forest coverage change showed a yearly difference because of the difference in annual precipitation.A 10% increase of forest coverage led to an increase of yearly evapotranspiration of 10.1 mm in dry years,8.6 mm in normal years,and 8.5 mm in wet years; but a decrease of yearly runoff of 9.0 mm in dry years,5.6 mm in normal ears,and 5.1 mm in wet years,respectively.3) There was also a monthly difference in the responces of yearly evapotranspiration and water yield to the increase of forest coverage.The evapotranspiration was increased in the Spring(March-May) and the early Summer(June),decreased in the period from the mid Summer(July and August) to the mid Autumn(September and Octomber),and not significally changed in the late Autumn(November) and Winter(December,January and Februry); whereas the runoff decreased in the Spring and Summer,but increased in the mid Autumn(September,Octomber),and not obviously changed in Winter.[Conclusions] In summary,the increase of forest coverage in the studied watershed led to an increase of yearly evapotranspiration and a decrease of yearly runoff.These hydrological impacts were more significant in dry years than in normal years and wet years.The hydological impacts of forest coverage change on the evapotranspiration and runoff diffred among the months,much significantly in the Spring and Summer than in the Autumn and Winter.
引文
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[2]杨文杰,刘国强,代军,等.西北地区林业发展战略研究[J].西北林学院学报,2004,19(1):149.YANG Wenjie,LIU Guoqiang,DAI Jun,et al.On the development strategy of forestry in northwestern area[J].Journal of Northwest Forestry University,2004,19(1):149.
[3]SUN G,ZHOU G,ZHANG Z,et al.Potential water yield reduction due to forestation across China[J].Journal of Hydrology,2006,328(34):548.
[4]ZHANG X P,ZHANG L,MCVICAR T R,et al.Modelling the impact of afforestation on average annual streamflow in the Loess Plateau,China[J].Hydrol Process,2008,22(12):1996.
[5]ZHANG Lulu,PODLASLY C,REN Ye,et al.Separating the effects of changes in land management and climatic conditions on long-term streamflow trends analyzed for a small catchment in the Loess Plateau region,NW China[J].Hydrological Processes,2014,28(3):1284.
[6]YU Pengtao,KRYSANOVA V,WANG Yanhui,et al.Quantitative estimate of water yield reduction caused by forestation in a water-limited area in northwest China[J].Geophysical Research Letters,2009,36(2):L2406
[7]张淑兰.土地利用和气候变化对流域水文过程影响的定量评价[D].北京:中国林业科学研究院,2011:25.ZHANG Shulan.The assessment of impact of land use change and climate variability on hydrological process in basin[D].Beijing:Chinese Academy of Forestry,2011:25.
[8]马雪华,张增哲,张仰渠.森林水文学[M].北京:中国林业出版社,1993:13.MA Xuehua,ZHANG Zengze,ZHANG Yangqu.Foresthydrology[M].Beijing:China Forestry Publishing House,1993:13.
[9]刘昌明,于静洁.森林拦蓄洪水的作用:以黄土高原林区为例[C]∥中国林学会森林水文与流域治理专业委员会.全国森林水文学术讨论会文集.北京:测绘出版社,1989:2.LIU Changming,YU Jingjie.The roles of forest in holding the flood:as an example of forest zone in loess plateau[C].Professiongal Committee of Forest Hydrology and Watershed Management.Forest Hydrological Seminar Corpus of China,1989.
[10]张淑兰,王彦辉,于澎涛,等.定量区分人类活动和降水量变化对泾河上游径流变化的影响[J].水土保持学报,2010,24(4):53.ZHANG Shulan,WANG Yanhui,YU Pengtao,et al.Study for separating the impact of precipitation variation and human activities on runoff change of the upper reaches of Jing River[J].Journal of Soil and Water Conservation,2010,24(4):53.
[11]六盘山水文考察报告[M].银川:宁夏人民出版社,2005:12.Investigation report of hydrology in Liu Pan Mountain[M].Yinchuan:Ningxia People’s Publishing House,2005:12.
[12]VALENTINA K,DIRK-INGMAR M W,ALFRED B.Development and test of a spatially distributed hydrological/water quality model for mesoscale watersheds[J].Ecol.Modell.,1998,106:261.
[13]VALENTINA K F H,FRANK W.Development of the ecohydrological model SWIM for regional impact studies and vulnerability assessment[J].Hydrological Processes,2005,19:763.
[14]HATTERMANN F,KRYSANOVA V,WATTENBACH M,et al.Interating groundwater dynamics in regional hydrological modeling[J].Environ.Model.Software,2004,19:1039.
[15]HATTERMANN F F,WATTENBACH M,KRYSANOVA V,et al.Runoff simulations on the mocroscale with the eohydrological model SWIM in the elbe catchmentvalidation and uncertainty analysis[J].Hydrological Processes,2005,19(3):693.
[16]苏布达,曹丽格,翟建青,等.SWIM模型使用指南[M].北京:气象出版社,2011:13.SHU Buda,CAO Lige,ZHAI Jianqing,et al.SWIM User manual[M].Beijing:China Meteorological Press,2011:13.
[17]张淑兰,于澎涛,王彦辉,等.泾河上游流域实际蒸散量及其各组分的估算[J].地理学报,2011,66(3):385.ZHANG Shulan,YU Pengtao,WANG Yanhui,et al.Estimation of actual evapotranspiration and its component in the upstream of Jinghe River[J].Acta Geographica Sinica,2011,66(3):385.
[18]王礼先,张志强.干旱地区森林对流域径流的影响[J].自然资源学报,2001,16(5):439.WANG Lixian,ZHANG Zhiqiang.Impacts of forest vegetation on watershed runoff in dryland areas[J].Journal of Natural Resources,2001,16(5):439.
[19]潘帅.区域水资源植被承载力计算系统开发及其应用[D].北京:中国林业科学研究院,2013:75.PAN Shuai.Developing of a calculation system for regional vegetation carrying capacity of water resources and its application in Jinghe upstrem[D].Beijing:Dissertation for the Master Degree from the Chinese Academy of Forestry,2013:75.
[20]张淑兰,于澎涛,张海军,等.泾河流域上游土石山区和黄土区森林覆盖率变化的水文影响模拟[J].生态学报,2015,35(4):1068.ZHANG Shulan,YU Pengtao,ZHANG Haijun,et al.A simulation study on the hydrological impacta of varying forest cover in stony mountain area and loess area of the upper reaches of Jinghe Basin[J].Acta Ecologica Sinica,2015,35(4):1068.
[21]SMAKHTIN V U.Low flow hydrology:A review[J].J Hydrol,2001,240(3):147.
[22]SMITH R E,SCOTT D F.The effects of afforestation on low flows in various regions of South Africa[J].Water S.A.,1992,18(3):185.
[23]WILCOX B P,HUANG Y.Woody plant encroachment paradox:rivers rebound as degraded grasslands convert to woodlands[J].Geophys Res Lett,2010,37(7):L7402.
[24]黄明斌,刘贤赵.黄土高原森林植被对流域径流的调节作用[J].应用生态学报,2002,13(9):1057.HUANG Mingbin,LIU Xianzhao.Regulation effect of forest vegetation on watershed runoff in the Loess Plateau[J].Chinese Journal of Applied Ecology,2002,13(9):1057.
[25]张建军,纳磊,董煌标,等.黄土高原不同植被覆盖对流域水文的影响[J].生态学报,2008,28(8):3597.ZHANG Jianjun,NA Lei,DONG Huangbiao,et al.Hydrological response to changes in vegetation covers of small watersheds on the Loess Plateau[J].Acta Ecologica Sinica,2008,28(8):3597.
[2]杨文杰,刘国强,代军,等.西北地区林业发展战略研究[J].西北林学院学报,2004,19(1):149.YANG Wenjie,LIU Guoqiang,DAI Jun,et al.On the development strategy of forestry in northwestern area[J].Journal of Northwest Forestry University,2004,19(1):149.
[3]SUN G,ZHOU G,ZHANG Z,et al.Potential water yield reduction due to forestation across China[J].Journal of Hydrology,2006,328(34):548.
[4]ZHANG X P,ZHANG L,MCVICAR T R,et al.Modelling the impact of afforestation on average annual streamflow in the Loess Plateau,China[J].Hydrol Process,2008,22(12):1996.
[5]ZHANG Lulu,PODLASLY C,REN Ye,et al.Separating the effects of changes in land management and climatic conditions on long-term streamflow trends analyzed for a small catchment in the Loess Plateau region,NW China[J].Hydrological Processes,2014,28(3):1284.
[6]YU Pengtao,KRYSANOVA V,WANG Yanhui,et al.Quantitative estimate of water yield reduction caused by forestation in a water-limited area in northwest China[J].Geophysical Research Letters,2009,36(2):L2406
[7]张淑兰.土地利用和气候变化对流域水文过程影响的定量评价[D].北京:中国林业科学研究院,2011:25.ZHANG Shulan.The assessment of impact of land use change and climate variability on hydrological process in basin[D].Beijing:Chinese Academy of Forestry,2011:25.
[8]马雪华,张增哲,张仰渠.森林水文学[M].北京:中国林业出版社,1993:13.MA Xuehua,ZHANG Zengze,ZHANG Yangqu.Foresthydrology[M].Beijing:China Forestry Publishing House,1993:13.
[9]刘昌明,于静洁.森林拦蓄洪水的作用:以黄土高原林区为例[C]∥中国林学会森林水文与流域治理专业委员会.全国森林水文学术讨论会文集.北京:测绘出版社,1989:2.LIU Changming,YU Jingjie.The roles of forest in holding the flood:as an example of forest zone in loess plateau[C].Professiongal Committee of Forest Hydrology and Watershed Management.Forest Hydrological Seminar Corpus of China,1989.
[10]张淑兰,王彦辉,于澎涛,等.定量区分人类活动和降水量变化对泾河上游径流变化的影响[J].水土保持学报,2010,24(4):53.ZHANG Shulan,WANG Yanhui,YU Pengtao,et al.Study for separating the impact of precipitation variation and human activities on runoff change of the upper reaches of Jing River[J].Journal of Soil and Water Conservation,2010,24(4):53.
[11]六盘山水文考察报告[M].银川:宁夏人民出版社,2005:12.Investigation report of hydrology in Liu Pan Mountain[M].Yinchuan:Ningxia People’s Publishing House,2005:12.
[12]VALENTINA K,DIRK-INGMAR M W,ALFRED B.Development and test of a spatially distributed hydrological/water quality model for mesoscale watersheds[J].Ecol.Modell.,1998,106:261.
[13]VALENTINA K F H,FRANK W.Development of the ecohydrological model SWIM for regional impact studies and vulnerability assessment[J].Hydrological Processes,2005,19:763.
[14]HATTERMANN F,KRYSANOVA V,WATTENBACH M,et al.Interating groundwater dynamics in regional hydrological modeling[J].Environ.Model.Software,2004,19:1039.
[15]HATTERMANN F F,WATTENBACH M,KRYSANOVA V,et al.Runoff simulations on the mocroscale with the eohydrological model SWIM in the elbe catchmentvalidation and uncertainty analysis[J].Hydrological Processes,2005,19(3):693.
[16]苏布达,曹丽格,翟建青,等.SWIM模型使用指南[M].北京:气象出版社,2011:13.SHU Buda,CAO Lige,ZHAI Jianqing,et al.SWIM User manual[M].Beijing:China Meteorological Press,2011:13.
[17]张淑兰,于澎涛,王彦辉,等.泾河上游流域实际蒸散量及其各组分的估算[J].地理学报,2011,66(3):385.ZHANG Shulan,YU Pengtao,WANG Yanhui,et al.Estimation of actual evapotranspiration and its component in the upstream of Jinghe River[J].Acta Geographica Sinica,2011,66(3):385.
[18]王礼先,张志强.干旱地区森林对流域径流的影响[J].自然资源学报,2001,16(5):439.WANG Lixian,ZHANG Zhiqiang.Impacts of forest vegetation on watershed runoff in dryland areas[J].Journal of Natural Resources,2001,16(5):439.
[19]潘帅.区域水资源植被承载力计算系统开发及其应用[D].北京:中国林业科学研究院,2013:75.PAN Shuai.Developing of a calculation system for regional vegetation carrying capacity of water resources and its application in Jinghe upstrem[D].Beijing:Dissertation for the Master Degree from the Chinese Academy of Forestry,2013:75.
[20]张淑兰,于澎涛,张海军,等.泾河流域上游土石山区和黄土区森林覆盖率变化的水文影响模拟[J].生态学报,2015,35(4):1068.ZHANG Shulan,YU Pengtao,ZHANG Haijun,et al.A simulation study on the hydrological impacta of varying forest cover in stony mountain area and loess area of the upper reaches of Jinghe Basin[J].Acta Ecologica Sinica,2015,35(4):1068.
[21]SMAKHTIN V U.Low flow hydrology:A review[J].J Hydrol,2001,240(3):147.
[22]SMITH R E,SCOTT D F.The effects of afforestation on low flows in various regions of South Africa[J].Water S.A.,1992,18(3):185.
[23]WILCOX B P,HUANG Y.Woody plant encroachment paradox:rivers rebound as degraded grasslands convert to woodlands[J].Geophys Res Lett,2010,37(7):L7402.
[24]黄明斌,刘贤赵.黄土高原森林植被对流域径流的调节作用[J].应用生态学报,2002,13(9):1057.HUANG Mingbin,LIU Xianzhao.Regulation effect of forest vegetation on watershed runoff in the Loess Plateau[J].Chinese Journal of Applied Ecology,2002,13(9):1057.
[25]张建军,纳磊,董煌标,等.黄土高原不同植被覆盖对流域水文的影响[J].生态学报,2008,28(8):3597.ZHANG Jianjun,NA Lei,DONG Huangbiao,et al.Hydrological response to changes in vegetation covers of small watersheds on the Loess Plateau[J].Acta Ecologica Sinica,2008,28(8):3597.