Time domain reflectometry coil probes for measuring thin surface layer soil moisture: Field tests over 21 years (2002-2022) under highly variable climate conditions in Mongolia

被引：1

作者：

Kaihotsu, Ichirow ^{[1
]}

Nissen, Henrik Hoffman ^{[2
]}

Aida, Kentaro ^{[3
]}

Asanuma, Jun ^{[4
]}

Hirose, Nozomu ^{[5
]}

Moldrup, Per ^{[6
]}

机构：

[1] Hiroshima Univ, Grad Sch Integrated Arts & Sci, Higashihiroshima 7398521, Japan

[2] Municipal Aalborg, Sect Technol & Environm, Stigsborg Brygge 5,POB 219, DK-9400 Noerresundby, Denmark

[3] Japan Aerosp Explorat Agcy JAXA, Earth Observat Res Ctr EORC, Tsukuba 3058505, Japan

[4] Univ Tsukuba, Ctr Res Isotopes & Environm Dynam CRiED, Tsukuba, Ibaraki 3058577, Japan

[5] Natl Inst Technol, Matsue Coll, Dept Civil Environm Engn, Matsue 6908581, Japan

[6] Aalborg Univ, Dept Built Environm, Thomas Manns Vej 23, DK-9220 Aalborg, Denmark

来源：

DISCOVER APPLIED SCIENCES | 2024年 / 6卷 / 07期

关键词：

Millimeter-scale TDR probe; Long-term field soil moisture measurement; Thin surface soil layer; Natural environmental change; Mongolia; WATER-CONTENT;

D O I：

10.1007/s42452-024-06006-w

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

A coil probe (CP) for time-domain reflectometry (TDR) with a sensor length of 40 mm (CP40) was developed for long-term field soil moisture measurements in a thin surface soil layer (0-3 cm depth). In laboratory, soil moisture measurements of CP40 were nearly identical to those of a traditional two-rod type TDR (2RTDR) probe (rod length: 15 cm, diameter: 0.3 cm, spacing: 3 cm). The CP40 measurement accuracy was between 0.01 m3/m3 and 0.03 m3/m3. For long-term field soil moisture measurements, five CP40 units were installed in the highly wetted soil at the Sanzai site (SS), which is in the permafrost area of the Taiga, and dry soil at the Mandalgobi site (MGS) in the semi-arid area of Mongolia. Four units accurately measured soil moisture at both sites over six years (2002-2007and 2008-2009). Three units succeeded in conducting precisely continuous soil moisture measurements between 2008 and 2022 at the MGS. Two units successfully measured soil moisture over 21 years at both the sites. The representativeness of the CP40 soil moisture measurements in highly wetted soils was low because of heavy rainfall and soil heterogeneity. The accuracy of CP40 soil moisture measurements in highly wetted soils was slightly lower than that of the traditional 2RTDR probe. However, the accuracy of the CP40 soil-moisture measurements in the dry soil was comparable to that of the traditional 2RTDR probe. CP40 units are durable and their field soil moisture measurements demonstrate stable and precise performance (bias, RMSE), even under severe environmental conditions. A 40 mm sensor TDR coil probe (CP40) was effective for near surface long-term field soil moisture measurements. The measurement accuracy of CP40 was close to that of a traditional 2RTDR probe in the laboratory condition. Four CP40 units successively succeeded in soil moisture measurements for 8 years and two units for 21 years in Mongolia.

引用

页数：15