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Lanzhou University (2018)

The Variation of Soil Temperature at Various Depths in the Badain Jaran Desert Hinterland

安然;

Titre : The Variation of Soil Temperature at Various Depths in the Badain Jaran Desert Hinterland

Auteur : 安然;

Grade : Master’s Theses 2018

Université : Lanzhou University

Résumé
The study of soil temperature changes in the desert hinterland was not only deepening and expansion of the special desert areas in soil temperature research,but also has an important impact on water evapotranspiration,water cycle,vegetation types,vegetation quantity and distribution.In this paper,we have selected the soil temperature data were from May 2012 to December 2017 for a total of five years and five months and observed by the Sumubari Jilin geothermal observation station in the hinterland of Badain Jaran Desert.Firstly,we analyzed seasonal,monthly,and inter-annual changes in soil temperature at different soil depths under the hinterland of the Badain Jaran Desert,respectively.Secondly,the geothermal data of different soil depths were used for spatial interpolation analysis,and compered with the soil temperature variation characteristics and laws of other regions.Thirdly,a stepwise regression model was used to conduct a regression analysis between the shallow soil temperature of 10 cm and the corresponding meteorological factors and the correlation degree.The research conclusions as follows :(1)At the Sumbabunir Jilin in the hinterland of the Badain Jaran Desert,the monthly mean temperature changes at eight soil depths all show a sinusoidal pattern.The soil temperature at 10 cm was firstly reached lowest value in February.However,it was in late March and early April for 180 cm.At 10 cm,the maximum soil temperature occurred at Mid-August,but the soil temperature can reach the highest value in late September and early October for 180 cm.From the soil depth of 10 cm to 180 cm,with the depth changes of 20 cm,40 cm,60 cm,80 cm,100 cm,140 cm,and 180 cm,the significant hysteresis was exhibited and the lag time was about one and half months.(2)There is no seasonal diurnal variation at the depth below 60 cm in the Badain Jaran Desert Hinterland.There is also no seasonal frozen soil.The variation range of soil temperature decreased with the increase of soil depth.There is a change in the direction of the vertical temperature gradient of the soil,which is transmitted from the shallow to the deep during the day and vice versa.(3)The results shown that the influence factors of soil temperature at 10 cm depth were different in the four seasons.And the temperature was the main influencing factor in four seasons,followed by the influence of precipitation,and the relative humidity was less affected,but the influence of precipitation and relative humidity in spring and winter was less and can be ignored.In the change of soil temperature throughout the year,air temperature was the main influence factor at 10 cm,followed by precipitation,.The relative humidity also had a certain influence,but the impact factor was small.

Mots clés : The Badain Jaran Desert; Soil temperature; Stepwise regression; Regional comparison; Depth variation;

Présentation (CNKI)

Page publiée le 15 mai 2019