【摘要】：青藏高原地處中低緯度帶,地域面積遼闊,地勢高低起伏較大,平均海拔4000多米,被譽為“世界屋脊”和地球的“第三極”,主要以其奇異的地貌,獨特的自然風光、豐富的自然資源及其對周邊地區(qū)乃至全球氣候與環(huán)境的影響,一直為國內(nèi)外各界所矚目。草地資源是發(fā)展第一產(chǎn)業(yè)(畜牧業(yè))的物質(zhì)基礎,草地資源對于以牧業(yè)為主的尼瑪?shù)貐^(qū)的經(jīng)濟社會發(fā)展具有舉足輕重的作用。目前,西藏尼瑪?shù)貐^(qū)天然草地面臨著諸多問題,主要以草地面積減少、質(zhì)量下降、草畜矛盾尖銳等問題,及時準確地了解西藏尼瑪?shù)貐^(qū)天然草地資源的時空分布狀況至關重要,而現(xiàn)代的檢測技術對于天然草場的時空變化監(jiān)測具有快速、及時、方便等的優(yōu)勢,以遙感監(jiān)測為主要監(jiān)測手段,其具有監(jiān)測面積大尺度、時間小尺度的優(yōu)勢,能夠?qū)崟r把握草地資源的變化狀況,為草地的動態(tài)監(jiān)測與管理提供了有力的技術支持。本研究采用了路線調(diào)查與遙感解譯相結(jié)合的方法,結(jié)合前人資料,對本區(qū)草地生態(tài)環(huán)境現(xiàn)狀、草地退化原因作了詳細的調(diào)查和分析。本次研究區(qū)地理位置特殊,生態(tài)環(huán)境基礎十分脆弱,由于長期以來對該區(qū)域的草地資源缺乏科學的利用與管理,過牧、濫牧現(xiàn)象已經(jīng)十分的突出,已經(jīng)導致研究區(qū)的草地嚴重退化和草地生態(tài)失調(diào),甚至部分區(qū)域出現(xiàn)大面積荒漠化和沙漠化等現(xiàn)象,保護研究區(qū)草地的生態(tài)環(huán)境,開展其生態(tài)環(huán)境建設,已經(jīng)刻不容緩。本研究選取西藏尼瑪?shù)貐^(qū)為對象,選取Landsat不同時間段的影像數(shù)據(jù),先對原始數(shù)據(jù)進行預處理,然后通過分析草地資源不同季節(jié)(主要選取夏季遙感影像,原因：夏季草場生長最為茂盛易于解譯,可以將不同的用地區(qū)分開來,尤其是草地與荒漠化土地分開,而秋季枯黃的草地與荒漠化的土地是無法區(qū)分開的。)的光譜特征,采用NDVI、監(jiān)督分類等方法提取草地資源相關的信息,并通過獲取的相關信息,對草地進行等級劃分,監(jiān)測、分析了研究區(qū)1988年、1999年、2009年和2015年草地的年際時空動態(tài)變化。(1)遙感數(shù)據(jù)的預處理Landsat遙感原始數(shù)據(jù)預處理主要有以下幾個步驟,首先是輻射校正,消除傳感器自身運行所產(chǎn)生的誤差,并將DN轉(zhuǎn)換為輻射亮度值,然后采用FLAASH模型進行大氣糾正,消除大氣和光照等因素對地物反射的影響。然后采用多項式糾正模型重新定位,并進行三次卷積內(nèi)插法重新采樣完成幾何精糾正。最后在ENVI軟件中進行投影轉(zhuǎn)換,保證所有研究數(shù)據(jù)為同一投影。結(jié)果顯示：輻射糾正和FLAASH模型大氣糾正較好的消除了大氣等對遙感數(shù)據(jù)的干擾,保證了NDVI指數(shù)的精確度。(2)草地資源信息提取將預處理后的Landsat數(shù)據(jù)進行選擇訓練樣區(qū),分析其可分離度及分離精度,進行監(jiān)督分類,并通過邏輯運算求得草地的NDVI指數(shù),結(jié)合NDⅥ指數(shù)大小及其分布,綜合考慮植被覆蓋度概況,將草地分為4個等級,保證等級內(nèi)差異最小,等級外差異最大,盡最大努力的提取同一草地在不同時空分布的等級信息,為后期的動態(tài)監(jiān)測與保護提供數(shù)據(jù)基礎。(3)草地資源動態(tài)監(jiān)測對不同年份的草地面積進行統(tǒng)計和不同等級草地面積及地理位置變化統(tǒng)計。從草地資源NDVI值角度分析：最近30年來,研究區(qū)草地總面積呈遞減趨勢,然而,不同等級的各種草地隨著時間的變化呈現(xiàn)出變化不一的趨勢,低等級草地面積表現(xiàn)為先減后增,中低等級草地和中等級草地面積都是表現(xiàn)出先增后減。(4)草地變化原因分析和草地發(fā)展建議結(jié)合遙感數(shù)據(jù)的解譯及數(shù)學運算分析和實地調(diào)查、驗證獲取的數(shù)據(jù)信息分析得出草地變化的主要原因有嚴重的超載過牧、研究區(qū)生態(tài)失衡、鼠害嚴重、毒草猖獗和一系列不合理的人類活動等,草地優(yōu)化發(fā)展的對策主要有加強對沙化退化草場綜合治理、防止超載過牧、加強自然保護區(qū)建設、草原水利建設和草原可持續(xù)發(fā)展體系和保護制度建設等。本研究以西藏尼瑪?shù)貐^(qū)為對象,采用多時相的Landsat影像數(shù)據(jù),充分發(fā)揮草地遙感的優(yōu)勢,分析了近30年西藏尼瑪?shù)貐^(qū)草地時空特征。本研究可以為尼瑪?shù)貐^(qū)的草地資源信息提取與時空動態(tài)變化特征分析提供了切實可行的技術方法,對政府及草地資源使用者及時準確地了解草地資源的時空分布現(xiàn)狀及變化趨勢,對促進地方畜牧業(yè)科學生產(chǎn)和保護生態(tài)環(huán)境的平衡與改善具有極其重要的參考價值及指導意義。
[Abstract]:The Qinghai-Tibet Plateau is located in the middle and low-latitude zone with a vast area, with a large and high terrain, with an average altitude of more than 4000 meters, and is known as the "third pole" of the "the roof of the world" and the earth, and is mainly characterized by its strange landforms and unique natural scenery. The rich natural resources and its impact on the surrounding area and even the global climate and environment have been attracting the attention of various circles at home and abroad. Grassland resources are the material base of developing the first industry (animal husbandry). At present, there are many problems in the natural grassland in the Nima area in Tibet, which is mainly based on the problems such as the decrease of the area of the grassland, the decline of the quality, the sharp contradiction of the grass and the livestock, and the timely and accurate understanding of the spatial and temporal distribution of the natural grassland resources in the Nima area of Tibet. The modern detection technology has the advantages of fast, timely and convenient monitoring on the space-time change of the natural grassland, and the remote sensing monitoring is the main monitoring means, which has the advantages of large scale and small time scale of the monitoring area, can control the change condition of the grassland resources in real time, And provides powerful technical support for the dynamic monitoring and management of the grassland. In this study, the method of combination of route survey and remote sensing interpretation is adopted, and the present situation of grassland ecological environment and the cause of grassland degradation are investigated and analyzed in detail in the light of the previous data. The geographical location of the research area is special, the ecological environment is very fragile, because of the lack of scientific utilization and management of the grassland resources in the region for a long time, the phenomenon of overgrazing and overgrazing has been very prominent, which has led to the serious degradation of the grassland in the research area and the ecological imbalance of the grassland, It is urgent to protect the ecological environment of the grassland in the research area and to carry out its ecological environment construction even in some areas, such as the large area of desertification and desertification. In this study, the image data of the Nama area in Tibet is selected, and the image data of the Landsat time period is selected, the original data is pre-processed firstly, and then the summer remote sensing image is mainly selected by analyzing the different seasons of the grassland resources (main selection of the summer remote sensing image). It is possible to separate different areas of use, in particular the grass and the desertification land, and the grass and desertification land in the fall of the autumn cannot be distinguished. ) The spatial and temporal dynamics of the grassland in 1988,1999,2009 and 2015 were analyzed by means of NDVI and supervised classification. (1) preprocessing Landsat remote sensing raw data of remote sensing data mainly comprises the following steps: firstly, the radiation correction is carried out, the error generated by the operation of the sensor is eliminated, the DN is converted into a radiation brightness value, the FLASH model is adopted for atmospheric correction, And the influence of factors such as atmosphere and light on the reflection of the figure is eliminated. Then the polynomial correction model is used for re-positioning, and the three-time convolution interpolation method is used for re-sampling to complete the geometric rectification. And finally, the projection conversion is carried out in the ENVI software to ensure that all the research data is the same projection. The results show that the radiation correction and the air correction of the FLASH model eliminate the interference of the atmosphere and the like on the remote sensing data, and the accuracy of the NDVI index is guaranteed. (2) the grassland resource information extracts the pre-processed Landsat data to select a training sample area, analyzes the separable degree and the separation precision, carries out supervision classification, and obtains the NDVI index of the grassland through a logical operation, combines the size of the ND VI index and the distribution thereof, and comprehensively considers the vegetation coverage profile, The grassland is divided into 4 grades, the difference in the guarantee level is the smallest, the difference between the grades is the largest, and the level information of the same grassland at different time and time is extracted to the best efforts, and the data base is provided for later dynamic monitoring and protection. (3) The dynamic monitoring of the grassland resources can be used for statistics of the area of the grassland in different years and the change of the area of the grassland and the geographical position. From the angle of NDVI of the grassland resources, the total area of the grassland in the research area is decreasing in the last 30 years. However, the different grades of the grassland show different trends over time. The area of medium-low-grade grassland and medium-grade grassland is the first increase and decrease. (4) The cause of the change of the grassland and the suggestion of the development of the grassland combine the interpretation of the remote sensing data and the analysis of the mathematical operation and the field investigation, and the analysis of the obtained data information shows that the main causes of the change of the grassland have serious overload and overgrazing, the ecological imbalance of the research area and the serious damage of the mouse, The countermeasures of grassland optimization and development mainly include strengthening the comprehensive treatment of the degraded grassland, preventing overgrazing, strengthening the construction of the nature reserve, the construction of the grassland water conservancy and the sustainable development system of the grassland and the construction of the protection system. In this study, the spatial and temporal characteristics of the grassland in the Nima area of Tibet were analyzed by using Landsat image data of a long time and using Landsat image data of the time. The study can provide a feasible technical method for the information extraction and spatial-temporal dynamic analysis of the grassland resources in the Nima area. The present situation and the changing trend of the spatial and temporal distribution of the grassland resources are known to the government and the users of the grassland resources in a timely and accurate manner. It is of great reference value and guiding significance to the promotion of the balance and improvement of the scientific production of local animal husbandry and the protection of the ecological environment.
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：S812.5

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本文編號：2439022