Publications

Xu, XB; Tang, XG (2016). REMOTE ESTIMATION OF ECOSYSTEM WATER-USE EFFICIENCY OF IRRIGATED AND RAINFED MAIZE CROPLANDS WITH MODIS DATA. FRESENIUS ENVIRONMENTAL BULLETIN, 25(5), 1383-1394.

Abstract
Accurate real-time monitoring of the variability in ecosystem water-use efficiency (WUE) is crucial for agricultural water management and food security. How to upscale in situ flux tower observations to regional or global scales remains challenging. Nevertheless, few studies attempted the direct estimation of WUE from remotely-sensed data. Four agricultural sites including irrigated and rainfed maize croplands revealed the prominent roles of temperature, solar radiation and vapor pressure deficit in driving WUE. MODIS-derived vegetation indices (NDVI and EVI) as proxies for plant responses to environmental controls, were also strongly correlated with crop WUE, thereby implying significant potential for remote quantification. Both performance of the MODIS-derived WUE from gross primary production (GPP) and evapotranspiration (ET), and the estimates on the use of MODIS EVI were independently evaluated using tower-based measurements. The results exhibited that ecosystem WUE was overly predicted at the beginning and ending of the crop-growth period and severely underestimated during the peak periods for two cropping systems based on the estimates from MODIS products, which were mainly ascribed to the error source from MODIS GPP. However, an alternative greenness model based on time-series MODIS EVI data provided fairly good estimates to capture the seasonal variations in WUE of maize croplands.

DOI:

ISSN:
1018-4619