Relationship between soil moisture of near surface and multiple depths of the root zone under heterogeneous land uses and varying hydroclimatic conditions

Rezaul Mahmood, Kenneth G. Hubbard

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

This paper presents an assessment of the relationship between near-surface soil moisture (SM) and SM at other depths in the root zone under three different land uses: irrigated corn, rainfed corn and grass. This research addresses the question whether or not near-surface SM can be used reliably to predict plant available root zone SM and SM at other depths. For this study, a realistic soil-water energy balance process model is applied to three locations in Nebraska representing an east-to-west hydroclimatic gradient in the Great Plains. The applications were completed from 1982 through to 1999 at a daily time scale. The simulated SM climatologies are developed for the root zone as a whole and for the five layers of the soil profile to a depth of 1.2 m. Over all, the relationship between near-surface SM (0-2.5 cm) and plant available root zone SM is not strong. This applies to all land uses and for all locations. For example, r estimates range from 0.02 to 0.33 for this relationship. Results for near-surface SM and SM of several depths suggest improvement in r estimates. For example, these estimates range from -0.19 to 0.69 for all land uses and locations. It was clear that r estimates are the highest (0.49-0.69) between near-surface and the second layer (2.5-30.5 cm) of the root zone. The strength of this type of relationship rapidly declines for deeper depths. Cross-correlation estimates also suggest that at various time-lags the strength of the relationship between near-surface SM and plant available SM is not strong. The strength of the relationship between SM modulation of the near surface and second layer over various time-lags slightly improves over no lags. The results suggest that use of near-surface SM for estimating SM at 2.5-30 cm is most promising.

Original languageEnglish (US)
Pages (from-to)3449-3462
Number of pages14
JournalHydrological Processes
Volume21
Issue number25
DOIs
StatePublished - Dec 1 2007
Externally publishedYes

Keywords

  • Land use
  • Modelling
  • Soil moisture

ASJC Scopus subject areas

  • Water Science and Technology

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