Variation of the Relative Soil Moisture of Farmland in a Continental River Basin in China

Guofeng Zhu,Hanxiong Pan,Qiaoqiao Li,Junju Zhou,Meihua Huang

doi:10.3390/w11101974

Guofeng Zhu, Hanxiong Pan + Show 3 more

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https://doi.org/10.3390/w11101974

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Abstract

The reduction of grain production caused by drought is one of the most serious problems caused by natural disasters. The relative soil moisture of farmland is the most important monitoring indicator for agricultural drought. This study investigated the relative soil moisture of farmland data from 38 agrometeorological stations in a continental river basin area in China from 1992 to 2012. Spatial and temporal variations of the relative soil moisture of farmland were studied using geostatistical analysis. The results show that, from 1992 to 2012, the average annual relative soil moisture of farmland in the continental river basin ranged from 62.5 to 86.1%, and the relative soil moisture of farmland was high in the marginal areas of basins and low in the central areas of basins and plateau areas. The relative soil moisture of farmland was high in the Tarim Basin and the Hexi Corridor, which are located in the northern Tianshan Mountains and the southern and northern Qilian Mountains, and was low from the northern Altun Mountains to the south of Lop Nor, the Turpan Depression, and the Tarbagatai Mountains. From 1992 to 2012, the annual average relative soil moisture of farmland in the continental river basins showed an increasing trend, with a growth rate of 0.57% yr−1. The variation tendency of the relative soil moisture of farmland was different in different river basins; the relative soil moisture showed a decreasing trend in the Mongolian Plateau and an increasing trend in other basin areas. The relative soil moisture of farmland increased in summer, spring, and winter, and decreased in autumn. The change in relative soil moisture of farmland was due to a combination of climatic factors, such as precipitation and temperature, as well as topography and glacial meltwater.

Highlights

Variability in relative soil moisture plays an important role in the interactions between the land surface and climate in the earth system, as well as in biogeochemical and hydrological cycling, vegetation, ecosystems, and agriculture in the landscape [1–3]
The relative soil moisture of farmland at a depth of 10 cm was between 62.5% and 83.6%, with an average value of 69.7%; the value at 20 cm was between 67.5% and 86.2%, with an average value of 74.7%; and the value at 50 cm was between 69.3% and 77.7%, with an average value of 73.7%
The variation of the relative soil moisture of farmland was larger in deep soil than in shallow soil

Summary

Introduction

Variability in relative soil moisture plays an important role in the interactions between the land surface and climate in the earth system, as well as in biogeochemical and hydrological cycling, vegetation, ecosystems, and agriculture in the landscape [1–3]. Relative soil moisture content is determined by soil water conditions, and can reflect most of the surface hydrological processes. As an important physical quantity in land surface processes, relative soil moisture content affects climate by changing the surface albedo, heat capacity, and the transport of sensible heat and latent heat into the atmosphere. Regional runoff and surface energy balance are significantly affected by changes in relative soil moisture [4]. It is very important to analyze the spatial and temporal characteristics of relative soil moisture in order to determine changes in relative soil moisture and to allow for the appropriate use of soil water resources to cope with climate change.

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