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Northwest A&F University (2019)

Characteristics of Soil Moisture and Temperature and Their Coupling Effects on Sloping Land in Loess Hilly Region

唐敏;

Titre : Characteristics of Soil Moisture and Temperature and Their Coupling Effects on Sloping Land in Loess Hilly Region

Auteur : 唐敏;

Grade : Doctoral Dissertation 2019

Université : Northwest A&F University

Résumé partiel
Sloping land is one of the main landform types in the loess hilly region.The area of sloping land above 7°accounts for 75.7%of the area of the loess hilly region.Sloping land is also the main source of soil erosion in the region.Therefore,the rational development and utilization of sloping land is of great significance for the ecological construction and the sustainable development of economy and society in the loess hilly region.In the arid and semi-arid loess hilly region with scarce water resources,understanding the soil moisture and temperature conditions of sloping land is an important prerequisite for rational development and utilization of sloping land.At the same time,the sloping land use pattern affects the soil moisture and temperature.Therefore,it is of great theoretical and practical significance to reveal the characteristics of soil moisture and temperature changes and their coupling effects under typical sloping land use patterns in the loess hilly region for efficient and sustainable utilization of sloping land resources.In this paper,four typical sloping land use patterns(i.e.,soybean sloping field,maize terraced field,jujube orchard,and grassland)in the loess hilly region were selected as the research objects.The variation characteristics of soil moisture and temperature,their responses to major environmental factors,and the complexity of soil moisture and temperature changes under different sloping land use patterns were studied by field positioning monitoring,laboratory experiments,and statistical analysis.A numerical model of one-dimensional vertical soil water-heat coupled transport was established.As an example,the temporal variation and spatial vertical distribution of soil moisture and temperature in jujube orchard were simulated and predicted.The effects of soil temperature gradient and root water uptake on soil water-heat coupled transport in jujube orchard were further studied.The main conclusions were summarized as follows :(1)The dynamic changes of soil moisture and temperature under different sloping land use patterns were elucidated.The consistent results were presented in four sloping land use patterns,with the soil moisture seasonal fluctuation in 0-60 cm layer and relatively flat change in 60-160 cm layer.The soil moisture of jujube orchard in 0-60 cm layer was significantly lower than that of other three sloping land use patterns(p<0.05)during the growing season both in the normal precipitation year(2014)and in the drought year(2015).The total water storage of 0-160 cm soil layer in jujube orchard in the normal precipitation year was 5.9%,6.6%,and 17.7%lower than that in soybean sloping field,maize terraced field,and grassland,respectively.The maize terraced field showed adequate soil water conservation capacity,with a low soil water deficit and the soil moisture in 0-160 cm layer being significantly higher than that of other three sloping land use patterns(p<0.05)during the growing season in the drought year.After typical rainfall,with the duration of drought,the soil moisture loss rate of jujube orchard increased significantly,while only moderate increase was observed in maize terraced field.For all sloping land use patterns,with the deepening of soil layer,soil temperature gradually decreased and the seasonal variation was also reduced.The jujube orchard showed obvious warming effect,which increased the soil temperature daily amplitude and daily range during the growing season.Contrarily,maize terraced field could decrease soil temperature daily and seasonal amplitude,and also reduced soil temperature daily range.In summary,as a week performance in conserving soil moisture and regulating soil temperature for jujube orchard,corresponding field management measures are urgently needed to effectively improve soil hydrothermal conditions and achieve sustainable development.

Mots clés : loess hilly region; sloping land use; soil moisture; soil temperature; soil water-heat coupling numerical simulation;

Présentation (CNKI) -> https://oversea.cnki.net/KCMS/detai...

Page publiée le 21 octobre 2020, mise à jour le 25 novembre 2021