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黄土丘陵区小流域土壤水分状态与空间模拟

State-space Simulation of Soil Moisture at Small Watershed Scale in Loess Hilly Region

【作者】 林坤

【导师】 焦峰;

【作者基本信息】 西北农林科技大学 , 地图学与地理信息系统, 2012, 硕士

【摘要】 水资源缺乏是制约黄土高原生态环境建设的主要因子。以小流域水分行为、生态效应及其优化调控为主线,深入了解流域水文生态特征,有助于持续、扎实地推进生态环境建设。本研究通过对黄土高原一个典型的小流域——贺庄沟流域的立地特征及其数量分析,准确并全面的获得了贺庄沟流域的立地环境信息。在此基础上,识别、筛选、确定土壤水分的影响因子,定性且定量的描述各影响因子对土壤水分的影响。然后运用ANUSPLIN软件的薄板光滑样条函数(Thin Plate Smoothing Spline, TPS)插值得到贺庄沟流域土壤水分的分布图,为小流域土壤水分的监测、管理和合理利用等提供科学依据。通过研究,得出以下结论:(1)贺庄沟流域同一土层土壤水分极大极小值差距较大,但离散程度较小;同一土层不同地点土壤水分相对来说变异性不大,随着土层的加深至140-200cm土层,土壤水分的变异接近一个定值;不同季节土壤水分的垂直分布不同,整体看来雨季后>雨季前>雨季中;(2)不同土地利用类型,土壤水分的分布有着显著性差异,但是有着基本相似的分布趋势:0-20cm土层至20-40cm土层,土壤水分变少,而40-120cm土层,随着土层深度的加深,土壤水分缓慢升高,120-200cm土层土壤水分稳定。(3)从地形因子分析,平地土壤水分含量最高,而坡向对贺庄沟流域土壤水分虽有影响但是差异不大;从土地利用类型因子分析,土壤含水量由高到低依次为:农用地、乔木林地、果园、草地、灌木林地;(4)影响贺庄沟流域土壤水分的环境因子按贡献率大小依次排序为:坡度、土地利用类型、温度、海拔、降雨、蒸发、坡向、坡位。其中坡度贡献率远远高于其他因子;(5)薄板光滑样条函数法插值得到的土壤水分分布图与采样点描述性统计结果趋势一致,其插值结果分布图随地形呈现过渡性变化,更符合土壤水分变化的实际情况;其插值结果要优于克里金插值,插值结果精度更高。

【Abstract】 Lack of water resources is the main factor restricting ecological environmentconstruction in the Loess Plateau. Taking a small watershed water behaviour, its ecologicaleffect and the optimal regulation for masterstroke, in-depth understanding of hydrological andecological characteristics, which is helpful to advance the ecological environmentconstruction solidly and continually. In this study, a typical small watershed on the LoessPlateau-He Zhuanggou catchment is studied. Through its site characteristics and quantitativeanalysis, site environmental information of HeZhuanggou catchment is obtained accuratelyand comprehensively. On this basis, factors that affect soil moisture are distinguished, filteredand identified, then they are described qualitatively and quantitatively. Then we getdistribution maps of soil moisture in Hezhuanggou catchment from Thin Plate SmoothingSpline (TPS) of ANUSPLIN interpolation, and provide a scientific basis for the smallwatershed soil moisture monitoring, management and rational utilization. Through theresearch, we can draw the following conclusions:(1) In the same soil layer for the soil water of Hezhuanggou catchment, there is a big gapbetween the maximum and minimum value, but a smaller degree of dispersion; in the samesoil layer at different locations of variability of the soil moisture, there is a little variability inrelatively, with the depths to140-200cm soil layer, the variation of soil moisture is close to aconstant value; In different seasons, the vertical distribution of the soil moisture are different,the soil moisture of after the rainy season> before the rainy season> during the rainy seasonas a whole;(2) In different land use types, there is a significant difference in the distribution of soilmoisture, but there is a similar distribution trend: of0-20cm to20-40cm soil layer, soilmoisture decreasing, but through40-120cm soil layer, with the deepening of the soil layer,soil moisture increases slowly, and it stable to120-200cm soil layer.(3) Analysis from the topographic factor, the soil moisture content of no aspect is highest,and to the soil water of the Hezhuanggou catchment, although aspect impact it but had littledifference. From the type of land use factor analysis, soil moisture content in descendingorder as follows: agricultural land, forestland, orchard, grassland, shrub land;(4) The soil moisture contribution rate of the environmental factors in decreasing order: slope, land use type, temperature, altitude, precipitation, evapotranspiration, aspect, slopeposition. Which the slope of the contribution rate is much higher than other factors;(5) The maps of soil moisture in Hezhuanggou catchment got from TPS interpolation areconsistent with the trend of descriptive statistical results of the sampling point, showing thetransitional changes with the topographic change. They are more in line with the actualsituation of the soil moisture changes; and the interpolation results are superior to those fromkriging interpolation, the interpolation results are more accurate.

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