Sub-metre mapping of surface soil moisture in proglacial valleys of the tropical Andes using a multispectral unmanned aerial vehicle

Oliver Wigmore, Bryan Mark, Jeffrey McKenzie, Michel Baraer, Laura K Lautz

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Surface soil moisture is a critical but often neglected component of the hydrologic budget. Within mountain environments, surface soil moisture is highly heterogeneous and challenging to measure. Point measurements are often poorly representative of larger areas, while satellite pixels are generally too coarse in these topographically varied landscapes. In the Cordillera Blanca, Peru, rapid glacier recession is impacting downstream water supply in timing, quantity and quality. Recent research has shown that these proglacial valleys provide vital ecosystem services and store considerable amounts of water within the groundwater systems. However, the spatial and temporal variability of soil water storage is poorly understood. In this tropical Andean setting, we use an unmanned aerial vehicle (UAV) with multispectral (visible, near infrared, thermal infrared) sensors to map sections of two proglacial valleys in the Cordillera Blanca, Peru at sub-metre resolution. We use the Temperature Vegetation Dryness Index (TVDI) (Sandholt et al., 2002), and apply it for the first time to UAV borne imagery to estimate absolute surface soil moisture through calibration with in-scene field measurements. Resulting surface soil moisture maps have 50 cm spatial resolution with an R2 value of 0.55 and 0.76 for the two study sites, Pachacoto and Llanganuco respectively. We analyse the multispectral orthomosaics and soil moisture maps to improve our understanding of the controls on spatial variability in surface soil moisture within the proglacial valleys of the Cordillera Blanca. The maps permit us to identify both important groundwater spring sources and areas where domestic grazing impacts observed soil moisture estimates. The high resolution observations provided by the UAV facilitate a greater understanding of fine scale heterogeneity within these environments.

Original languageEnglish (US)
Pages (from-to)104-118
Number of pages15
JournalRemote Sensing of Environment
Volume222
DOIs
StatePublished - Mar 1 2019

Fingerprint

Soil moisture
meters (equipment)
Unmanned aerial vehicles (UAV)
valleys
soil moisture
soil water
valley
cordillera
Peru
Groundwater
groundwater
Infrared radiation
mountain environment
Glaciers
soil water storage
Springs (water)
glaciers
vegetation index
unmanned aerial vehicles
vehicle

Keywords

  • Cordillera Blanca
  • Multispectral
  • Soil moisture
  • Thermal
  • Unmanned aerial vehicle

ASJC Scopus subject areas

  • Soil Science
  • Geology
  • Computers in Earth Sciences

Cite this

Sub-metre mapping of surface soil moisture in proglacial valleys of the tropical Andes using a multispectral unmanned aerial vehicle. / Wigmore, Oliver; Mark, Bryan; McKenzie, Jeffrey; Baraer, Michel; Lautz, Laura K.

In: Remote Sensing of Environment, Vol. 222, 01.03.2019, p. 104-118.

Research output: Contribution to journalArticle

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