本文關鍵詞： 延河流域 土地利用景觀格局 水沙變化 恢復階段　出處：《中國科學院研究生院（教育部水土保持與生態(tài)環(huán)境研究中心）》2015年碩士論文　論文類型：學位論文

【摘要】：退耕還林(草)政策在黃土高原地區(qū)實施已逾20載,流域內(nèi)土地利用景觀格局和徑流泥沙發(fā)生顯著變化,針對這一現(xiàn)象,本論文以延河流域為研究區(qū),基于甘谷驛水文站的長期實測水沙數(shù)據(jù)(1970-2010),結(jié)合四期遙感影像資料(1978年、1990年、2000年、2010年),采用GIS、RS和野外人工模擬降雨等技術(shù)手段,運用景觀生態(tài)學、數(shù)理統(tǒng)計和定性定量相結(jié)合的分析方法。在流域尺度上,對延河流域的土地利用景觀格局和徑流泥沙變化特征進行分析總結(jié),并建立景觀格局指數(shù)和徑流泥沙指標之間的關系;同時,在坡面尺度上,研究不同恢復階段的人工刺槐林地、人工檸條林地和自然恢復草地的坡面產(chǎn)流產(chǎn)沙特征及減流減沙效益,為解釋流域尺度上土地利用景觀格局變化對徑流泥沙的影響提供理論基礎。研究取得的主要結(jié)論如下:(1)經(jīng)過多年的生態(tài)建設和流域綜合治理,尤其是退耕還林(草)工程的實施,延河流域的土地利用景觀格局發(fā)生了顯著變化。在斑塊水平上,耕地和草地的破碎度較高,斑塊形狀也較復雜,林地、建設用地和水域斑塊分布趨于集中化,破碎度較小,形狀較為簡單;在景觀水平上,以耕地為主導的土地利用景觀格局已不復存在,而以林地和草地為主導的新的土地利用景觀格局正在形成,景觀格局大致經(jīng)歷了“耕地主導-相對平衡-林草主導”的變化過程,向集中化和簡單化的方向發(fā)展,由于林草植被的減蝕作用,以林草為主導的景觀格局有利于生態(tài)環(huán)境的改善。(2)延河近40年的水沙量均呈下降趨勢,輸沙量的下降幅度高于徑流量,Mann-Kendall趨勢檢驗表明,2005年為水沙發(fā)生突變的年份。其變化過程大致經(jīng)歷了三個階段,1970-1986年為水沙波動期,1987-1996年為豐水豐沙期,1997-2010年為枯水枯沙期。造成這種變化的主要原因不是降雨,而與流域內(nèi)植被恢復引起土地利用的階段性變化有關。(3)在流域尺度上,以耕林草為主導的土地利用景觀格局與水沙變化關系密切。在景觀類型水平上,延河流域耕地斑塊的分離度指數(shù)、林地斑塊的連通度和草地斑塊的斑塊個數(shù)對流域的徑流過程影響較大,耕地斑塊的邊緣密度、林地斑塊的斑塊所占景觀面積比、草地斑塊的散布與并列指數(shù)與流域的輸沙過程關系密切�；貧w方程表明林地和草地斑塊的面積越大和連通性越高,分布越集中;耕地受人類活動的擾動越弱,分布越分散,則流域內(nèi)的水土流失程度越弱,反之則越強。在景觀水平上,延河流域景觀格局的斑塊個數(shù)、平均斑塊面積、多樣性指數(shù)和聚集度指數(shù)共同影響著流域的徑流和輸沙過程�；貧w方程表明景觀的破碎化程度越弱,多樣性越豐富,分布越集中,流域的徑流輸沙量越小。(4)在坡面尺度上,植被恢復年限是影響延河流域自然恢復草地、人工檸條林地和人工刺槐林地產(chǎn)流產(chǎn)沙的一個重要因素。同一植被恢復方式,在不同恢復階段的徑流率和產(chǎn)沙強度變化規(guī)律各不相同。隨恢復年限的增加,自然恢復草地和人工檸條林地的徑流率和產(chǎn)沙強度都減小,而人工刺槐林地則表現(xiàn)出徑流率差異不顯著,產(chǎn)沙強度增大,主要是由于人工刺槐林地的郁閉度較高和樹木高度增加所致。各恢復階段的累積徑流量(QW)、累積產(chǎn)沙量(QS)和降雨歷時之間均存在較好的二次函數(shù)關系,而累計產(chǎn)沙量和累計產(chǎn)流量之間的相互關系可通過冪函數(shù)來反應。(5)對于不同恢復階段的自然恢復草地、人工檸條林地和人工刺槐林地,其減沙效益均大于減流效益,這也很好的解釋了流域尺度上泥沙減少幅度大于徑流的問題。人工刺槐林地的減流減沙效益最為突出,處在一個很高的水平,具有蓄水減沙的水土保持功效,自然恢復草地和人工檸條林地的減水減沙效益都隨恢復年限的增加而增加,具有直接攔沙的水土保持功效。同時,處在恢復初期(0~8年)的自然恢復草地和人工檸條林地,生態(tài)功能仍然比較脆弱,以及恢復后期(16年以上)的人工刺槐林地,如果地表植被遭到破壞,仍然是暴雨條件下產(chǎn)沙的主要來源之一,因此,在植被恢復重建過程中,要做好封育、禁牧等保護措施。
[Abstract]:Returning farmland to forest (grass) policy has been implemented for more than 20 years in the Loess Plateau area, the land use landscape pattern and runoff sediment change significantly in response to this phenomenon, this thesis in Yanhe River Basin as the study area, Gangu Yi long term hydrological and sediment data station based on (1970-2010), combined with the remote sensing image data four (1978, 1990, 2000, 2010), by GIS, RS and field artificial rainfall simulation technique, using landscape ecology, analysis method of combining mathematical statistics and qualitative and quantitative. In the basin scale, the landscape pattern and the variation of runoff and sediment characteristics of land use along the river basin are analyzed and summarized, and the establishment of relations between landscape pattern index and runoff sediment index; at the same time, in the slope scale, study the different recovery stages of Robinia pseudoacacia plantation, Artificial Caragana forest and natural grassland restoration runoff in Saudi Arabia Sign and runoff and sediment reduction benefits, provide a theoretical basis for the effect of the change of the landscape patterns of land interpretation on basin scale on the runoff and sediment. The main conclusions are as follows: (1) after years of comprehensive management and ecological construction of river basin, especially in returning farmland to forest (grass) the implementation of the project, changed the landscape pattern of land use in Yanhe River Basin. At patch level, arable land and grassland fragmentation is high, the patch shape is more complex, woodland, centralized land and water were more construction, fragmentation, simple shapes; at the landscape level, the farmland landscape pattern of land use is no longer dominated there, in the woodland and grassland dominated the new land use landscape pattern is formed, the landscape pattern has experienced the change process of cultivated land dominant relative balance - grass, leading to centralization and simplification The direction of development, due to erosion of vegetation, the forest grass is dominant landscape pattern is conducive to the improvement of the ecological environment. (2) water sediment in nearly 40 years showed a downward trend, the decline rate is higher than sediment runoff, Mann-Kendall trend test showed that in 2005 for the water and sediment mutation year. The change process has experienced three stages, 1970-1986 years for a period of 1987-1996 years for the fluctuation of water and sand, wet wet period, 1997-2010 years of withered water and sediment. The main reason for this change is not the rainfall, and watershed vegetation restoration caused by land use changes. (3) in the. The basin scale, the close relationship between landscape pattern and land use change of water and sand to plow grass dominated. At the level of landscape types, cultivated land in Yanhe River Basin separation index, patch number convection connectivity and grassland patches of woodland patches The runoff process area affected farmland patch edge density, patches of woodland patches for landscape area ratio, the relationship between sediment process and river basin interspersion and juxtaposition index of grassland patches closely. Regression equation indicated that the woodland and grassland patch area more and more high connectivity, the distribution is more concentrated; the disturbance of human activities the weaker by the arable land, the distribution is more dispersed, the degree of soil erosion in the watershed is weak, whereas the more strong. At the landscape level, the number of patches of Yanhe River watershed landscape pattern, average patch area, diversity index and aggregation index affect the watershed runoff and sediment process. The regression equation shows that the fragmentation the degree of landscape diversity is weaker, more rich, more concentrated distribution, basin runoff and sediment transport amount is smaller. (4) in the slope scale, vegetation restoration years Grassland Natural Restoration effect of Yanhe River Basin, Artificial Caragana forest and people One of the important factors in industrial locust runoff and sediment. In the same way to restore vegetation, variation of runoff and sediment of different restoration stages are different. With the increase of the strength of the recovery period, runoff rate of natural grasslands and Artificial Caragana forest and sediment yield intensity decreased, and the performance of Robinia pseudoacacia plantation the runoff rate had no significant difference, sediment yield intensity increased, mainly due to the high degree of Robinia pseudoacacia plantation canopy and tree height increased. The recovery phase of the cumulative runoff (QW), cumulative sediment yield and rainfall duration (QS) are in quadratic function relationship better, and the relationship between the cumulative sediment yield and cumulative runoff to reaction by power function. (5) for different recovery stages of natural restoration of grassland, woodland and Artificial Caragana microphylla Robinia pseudoacacia plantation, the benefits of sediment reduction were greater than the current reducing efficiency, this is also a good solution The release of basin scale sediment reduction is greater than the runoff. Locust woodland runoff and sediment reduction benefits are most prominent, at a very high level, has the functions of water storage and sediment reduction of soil and water conservation, water and natural restoration of grassland and Artificial Caragana Plantation is increased with the increase of time of sediment reduction efficiency that has a direct effect on Soil and water conservation of sediment. At the same time, in the early stage of restoration (0~8) restoration of natural grassland and Artificial Caragana forest, ecological function is still weak, and the recovery period (16 years) of Robinia pseudoacacia plantation, if the destruction of surface vegetation, is still one of the main sources of sediment, heavy rain conditions therefore, in the vegetation restoration process, to do a good job of fencing, grazing and other protective measures.

【學位授予單位】：中國科學院研究生院（教育部水土保持與生態(tài)環(huán)境研究中心）
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P901;S157

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