小理河流域径流泥沙对气候和土地利用变化的响应研究

发布时间：2018-05-16 07:46

  本文选题：极端气候变化 + 土地利用时空变化　； 参考：《西北农林科技大学》2017年博士论文

【摘要】：研究气候变化和人类活动对流域水沙变化的影响,不但为流域水沙灾害的预警提供理论支持,也为科学评价生态建设的环境效应提供重要科学依据。本论文针对当前极端降水变化和土地利用空间格局对流域水沙影响研究的不足,以黄河中游黄土丘陵沟壑区小理河流域为研究区,采用滑动平均、距平分析、Sen斜率估计法、Mann-Kendall非参数检验和突变点检验法等,分析了小理河流域1959-2013年极端降水、极端气温、径流、泥沙的动态变化特征;利用GIS技术和土地利用转移矩阵、土地利用动态度、空间自相关格局分析、景观格局分析等方法,分析了小理河流域1990年以来土地利用的时空过程、土地利用空间自相关格局、土地利用景观格局的时空变化及其随地形变化的空间分异特征;基于对径流和泥沙突变点检验,筛选了影响流域径流和输沙的最优极端降水指标,利用双累积曲线法和回归分析法量化了极端降水变化和人类活动对流域径流泥沙变化的贡献率;在对SWAT模型参数率定和模型验证的基础上,通过输入不同的土地利用和气候情景,探讨流域径流泥沙对土地利用景观格局变化的响应机制,并定量研究流域径流泥沙对气候变化、土地利用变化和其他人类活动的响应特征。主要研究结论如下:(1)55 a间,年、汛期、春季、夏季、秋季降水量皆呈不显著减少趋势,而冬季降水量呈不显著增加趋势。17个极端降水指标(R10、R20、R50、R10p、R20p、R50p、R1d、R5d、SDII、R90p、R90t、R95p、R95t、R99p、R99t、CDD、CWD)中,仅最长连续干旱天数CDD和平均降水强度SDII呈不显著增加趋势,而其他15个极端降水指标均呈不显著减少趋势。年和四季平均气温均呈增加趋势,其中,年、春季、冬季气温呈显著增加趋势。16个极端气温指标中,冷指标(FD、ID、TN10p、TX10p、TNn、CSDI)呈减少趋势,其中ID、TX10p、TN10p呈显著减少趋势;暖指标(TR、HD、SU、TN90p、TX90p、TNx、TXn、TXx、WSDI和DTR)呈增加趋势,其中SU、DTR、HD、TN90p呈显著增加趋势,说明流域变暖趋势明显。(2)流域各土地利用类型都表现出全局空间正自相关特性,但空间正自相关性随着距离的增加而逐渐减弱。土地利用类型存在不同的局部空间聚集或异常特征,局部聚集区随高程、坡度和坡向的变化呈现空间分异。从1990年到2009年,流域景观格局破碎化程度增高,景观形状趋于复杂化,景观类型趋于多样化,景观异质性增加。景观格局指数与高程、坡度和坡向有显著的相关性。(3)55 a间,流域年、汛期径流量和输沙量呈极显著减少趋势,年和汛期径流量年均减少量分别为29.13×104 m3和18.6×104 m3,年和汛期输沙量年均减少量分别为6.33×104 t和6.49×104 t。1970年为小理河流域径流泥沙变化的突变年。据此,将整个研究时段划分为两个时期:1959-1970年基准期(天然情景期)和1971-2013年措施期。与基准期相比,措施期年和汛期径流量分别减少近40%和50%,年和汛期输沙量分别减少近72%。在基准期,流域径流量和输沙量与降水量、汛期降水量和16个极端降水指标之间相关系数变化于0.28~0.9之间,而在措施期流域径流量和输沙量与各降水指标之间相关系数变化于0.18~0.62之间;说明在基准期径流量、输沙量受降水影响较大,而在措施期径流量、输沙量受到降水和人类活动二者共同影响。在基准期、措施期和整个研究期,R90p(大于1961-1990年90%分位值的降水量总量)是各降水指标中与径流量、输沙量相关性最好的降水指标。(4)以R90p作为表征极端降水的最佳降水指标,评估了极端降水变化和人类活动对流域径流泥沙变化的贡献率。结果表明,在20世纪70、80年代和1999-2013年,人类活动是影响流域径流泥沙变化的主要因素,人类活动对径流量减少的贡献率分别为57.3%、62.1%和75.4%,人类活动对输沙量减少的贡献率分别为91.8%、92.9%和90.3%,人类活动对输沙量的影响大于其对径流量的影响。而在1990-1998年,极端降水变化是影响流域径流泥沙变化的主要因素,R90p对径流量、输沙量减少的贡献率分别为78.2%和57.9%,极端降水变化对径流量的影响大于其对输沙量的影响。(5)构建了适用于小理河流域的SWAT模型参数库,通过模型参数敏感性分析、率定和模型精度验证,模拟效果评价指标R2、NSE和PBAIS分别在0.84~0.89、0.80~0.86和-7.6%~2.3%之间,说明模型模拟效果较好。基于率定的SWAT模型,输入不同的土地利用和气候情景,分析了流域土地利用景观格局变化对径流和泥沙的影响,评估了气候变化、土地利用变化和其他人类活动对流域径流泥沙变化的贡献率。结果表明:流域土地利用景观格局显著影响流域径流和输沙。流域径流量和输沙量与斑块数量、斑块密度、景观形状指数和香农多样性指数呈显著正相关,而二者与最大斑块面积比例、斑块凝聚度、斑块蔓延度和香农均匀度指数呈显著负相关。以1971-1998年为基准,1999-2013年气候变化和土地利用变化对径流减少的贡献率分别为29.8%和70.2%,对输沙量减少的贡献率分别为13%和87%。同时,1999-2013年土地利用变化以外的其他人类活动(如工程建设、水保措施等)对流域径流量、输沙量减少的贡献率分别为5.2%和3.4%。
[Abstract]:The study of the effects of climate change and human activities on water and sediment changes in the basin not only provides theoretical support for the early warning of water and sediment disasters in the basin, but also provides an important scientific basis for the scientific evaluation of the environmental effects of ecological construction. The Xiali River Basin in the middle reaches of the middle reaches of the river is the study area. The dynamic changes of extreme precipitation, extreme temperature, runoff and sediment in the 1959-2013 years of the Xiaoli River Basin are analyzed by means of sliding average, anomaly analysis, Sen slope estimation, Mann-Kendall nonparametric test and mutation point test. The GIS technology and the transfer moment of land use are used. Array, land use dynamics, spatial autocorrelation analysis and landscape pattern analysis, the spatio-temporal process of land use in the Xiaoli River Basin since 1990, the spatial autocorrelation pattern of land use, spatial and temporal variation of land use landscape pattern and the spatial differentiation characteristics with the terrain change, based on the change of runoff and sediment The optimal extreme precipitation indexes affecting runoff and sediment transport are screened. The contribution rate of extreme precipitation changes and human activities to runoff and sediment changes in watershed is quantified by using double cumulative curve method and regression analysis method. On the basis of parameter rate determination and model verification of SWAT model, different land use and climate scenarios are input. The response mechanism of runoff and sediment on land use landscape pattern changes is discussed, and the response characteristics of runoff and sediment on climate change, land use change and other human activities are studied. The main conclusions are as follows: (1) 55 A, year, flood season, spring, summer, and autumn precipitation are not significantly reduced, and winter precipitation No significant increase trend of.17 extreme precipitation index (R10, R20, R50, R10p, R20p, R50p, R1d, R5d, SDII, R90p), only the longest continuous drought days and average precipitation intensity, but the other 15 extreme precipitation indexes are not significantly reduced. The cold index (FD, ID, TN10p, TX10p, TNn, CSDI) showed a decreasing trend in the year, spring, and winter temperature, in which the cold index (ID, TX10p, TN10p, CSDI) showed a decreasing trend, and the warm index (TR, HD, ID) showed an increasing trend. It shows that the trend of watershed warming is obvious. (2) all types of land use in the basin show the positive autocorrelation in the global space, but the positive autocorrelation of the space gradually decreases with the increase of distance. There are different local spatial aggregation or abnormal characteristics of the land use type, and the local agglomeration area presents the space with the elevation, the slope and the slope direction. From 1990 to 2009, landscape pattern fragmentation increased, landscape shape tended to be complex, landscape type tended to diversify and landscape heterogeneity increased. The landscape pattern index was significantly correlated with elevation, slope and slope direction. (3) 55 A, river basin year, flood season runoff and sediment transport volume showed a very significant reduction trend, year and flood period diameter The annual decrease of flow rate is 29.13 x 104 m3 and 18.6 x 104 m3 respectively. The annual and flood sediment transport annual average decrease is 6.33 x 104 T and 6.49 x 104 t.1970 year is the change year of runoff and sediment in the Xiaoli River Basin. According to this, the whole study period is divided into two periods: 1959-1970 years datum period (NATURAL scenario period) and 1971-2013 year period. Compared with the datum period, the annual and flood period runoff decreased by nearly 40% and 50% respectively, and the sediment transport in the year and flood season decreased by nearly 72%. in the datum period, and the correlation coefficient between the runoff and sediment discharge and the precipitation, the precipitation in the flood season and the 16 extreme precipitation indexes changed in the 0.28~0.9. The correlation coefficient between precipitation indexes varies between 0.18~0.62, indicating that in the base period runoff, sediment transport is greatly influenced by precipitation, while in the period of measure runoff, the amount of sediment is affected by the two people of precipitation and human activities. In the datum period, in the period of measure and in the whole study period, the total amount of R90p (the total amount of precipitation over 1961-1990 years 90%) is reduced. In the water index, the best precipitation index related to runoff and sediment transport is the best. (4) R90p is used as the best precipitation indicator for extreme precipitation, and the contribution rate of extreme precipitation and human activity to runoff and sediment change in river basin is evaluated. The results show that in the twentieth Century and 1999-2013 years, human activity was the influence of runoff and sediment change in the basin. The contribution rate of human activity to runoff reduction is 57.3%, 62.1% and 75.4% respectively. The contribution rate of human activities to sediment transport is 91.8%, 92.9% and 90.3%, respectively. The effect of human activity on sediment transport is greater than that of its runoff. In the 1990-1998 year, the change of extreme precipitation is the main factor affecting the change of runoff and sediment in the basin. The contribution rate of R90p to the decrease of runoff and sediment transport is 78.2% and 57.9% respectively. The influence of extreme precipitation on the runoff is greater than that of its effect on the sediment transport. (5) a parameter library of SWAT model suitable for the Xiaoli river basin is constructed, and the model parameter sensitivity analysis, rate determination and model accuracy verification, and the simulation effect evaluation index R2, NSE And PBAIS between 0.84~0.89,0.80~0.86 and -7.6%~2.3%, respectively, indicating that model simulation results are better. Based on the rate determined SWAT model, input different land use and climate scenarios, analyze the effects of landscape pattern changes on runoff and sediment, and evaluate the climate change, land use change and other human activities to the basin. The results showed that the landscape pattern of the land use landscape significantly affected the runoff and sediment transport in the basin. The runoff and sediment yield of the basin were significantly positively correlated with the number of patches, patch density, the landscape shape index and the Shannon diversity index, while the proportion of the two and the largest patch area, the degree of patch cohesion, the spread of plaque and the fragrance of the scent. The agricultural evenness index has a significant negative correlation. The contribution rate of the 1999-2013 year climate change and the land use change to the runoff reduction is 29.8% and 70.2%, respectively, and the contribution rate to the decrease of sediment transport is 13% and 87%., respectively, and other human activities other than the change of land use for 1999-2013 years (such as engineering construction and water conservation measures). The contribution rates to runoff and sediment discharge were 5.2% and 3.4%. respectively.

【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：F301.2;P333;P467
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本文编号：1896042