黄土高原样带尺度实际蒸散量时空变化研究

发布时间：2018-05-13 18:16

本文选题：实际蒸散量 + 遥感　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：水资源分布格局变化和生态系统息息相关,而蒸散量作为水文循环和水资源分配利用的重要依据,影响全球或区域的气候、生态和农业生产。研究区域实际蒸散量,可以为水资源的高效利用和分配提供理论依据。黄土高原属于我国水土流失严重和生态环境脆弱之最的区域,气候从半湿润、半干旱渐变至干旱,年均降水量从东南向西北递减,土壤从重土壤、中土壤变化到沙土,植被从乔木、灌木向草原过渡。本研究在黄土高原中部选取一条样带,运用MODIS数据和国内外广泛运用的SEBAL模型估算区域实际蒸散量,分析退耕还林(草)工程实施以来黄土高原实际蒸散量的演变趋势。以2000年、2004年、2008年、2012年四年的MODIS数据、DEM数据和气象资料为基础,反演地表特征参数,计算各地表通量,估算黄土高原样带区域日蒸散和生长季蒸散情况。使用改进的Biome-BGC模型计算的实际蒸散量与SEBAL估算的实际蒸散量进行对比验证,评价遥感估算实际蒸散量的准确性。得到如下主要研究结果:(1)退耕还林草工程实施以来,植被覆盖度在整体呈上升趋势,其中2000年植被覆盖度为54.8%,2003年上升至61.3%,2007年达到最大值65.3%,之后植被覆盖度随年降水的变化在较高水平波动。(2)研究区实际蒸散量年内变化呈“单峰”特征,日实际蒸散量平均值从90日至310日的变化趋势是:先由大约1mm/d,逐渐增加至5mm/d,再减少至1mm/d;月实际蒸散量平均值从4月的50 mm/m逐渐增加至7月的300 mm/m,再减少至10月的30mm/m。实际蒸散量年际变化趋势是从2000年逐渐增加,至2008年达到最大值,2012又有所降低。(3)实际蒸散量呈现由东南向西北减少的空间分布特征,四个分区2000~2012年的变化趋势为:荒漠带生长季实际蒸散量基本不变,草原带和森林—草原带的生长季实际蒸散量先增后减,森林带的生长季实际蒸散量一直下降。四个区实际蒸散量对退耕还林(草)工程的响应不同。
[Abstract]:The change of distribution pattern of water resources is closely related to ecosystem, and evapotranspiration, as an important basis of hydrological cycle and water resources distribution and utilization, affects the climate, ecology and agricultural production of the whole world or region. The study of regional evapotranspiration can provide theoretical basis for efficient utilization and distribution of water resources. The Loess Plateau is the region with the most serious soil erosion and fragile ecological environment in China. The climate changes from semi-humid, semi-arid to arid, the annual precipitation decreases from southeast to northwest, the soil changes from heavy soil to sandy soil. Vegetation transitions from trees and shrubs to grasslands. In this study, a sample belt was selected in the middle of the Loess Plateau, and the actual evapotranspiration of the Loess Plateau was estimated by using MODIS data and the widely used SEBAL model at home and abroad, and the evolution trend of the actual evapotranspiration of the Loess Plateau since the implementation of the conversion of cropland to Forest (Grass) Project was analyzed. Based on the MODIS data of 2000, 2004, 2008 and 2012, Dem data and meteorological data, the surface characteristic parameters were retrieved, the surface fluxes were calculated, and the daily evapotranspiration and the growing season evapotranspiration in the Loess Plateau transect region were estimated. The actual evapotranspiration calculated by the improved Biome-BGC model is compared with the actual evapotranspiration estimated by SEBAL to evaluate the accuracy of remote sensing estimation of the actual evapotranspiration. The main research results are as follows: (1) since the implementation of the project of returning cropland to forest and grass, the vegetation coverage has been on the rise as a whole. The vegetation coverage was 54.8% in 2000, increased to 61.3% in 2003, reached a maximum of 65.3% in 2007, and then the change of vegetation coverage with annual precipitation fluctuated at a higher level. The average daily actual evapotranspiration increased from 90 to 310 days, gradually increased from about 1 mm / d to 5 mm / d, then decreased to 1 mm / d, and the monthly average of actual evapotranspiration gradually increased from 50 mm/m in April to 300 mm / m in July and then decreased to 30 mm / m in October. The annual variation trend of actual evapotranspiration increased gradually from 2000 to reach the maximum in 2008 and then decreased in 2012) the actual evapotranspiration decreased from southeast to northwest. The change trend of the four zones from 2000 to 2012 is as follows: the actual evapotranspiration of the desert zone is basically unchanged, the actual evapotranspiration of the grassland zone and the forest-grassland zone increases first and then decreases, and the actual evapotranspiration of the forest belt decreases continuously in the growing season. The response of the actual evapotranspiration of the four districts to the conversion of farmland to forest (grass) projects is different.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S161.4

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