Spatial-temporal change analysis of evapotranspiration in the Heihe River Basin

Abstract

Evapotranspiration (ET) is one important component of hydrological process. It is also a limited factor for ecological environment conservation. The unreasonable utilization of water resources resulted in many problems in the Heihe River Basin, such as the over exploited of water resources, especial the ground water, the river flow decrease, land degradation. A correct understanding of the water consumption characteristics is undoubtedly a base of achieving the sustainable development of society, economy, and improving the eco-environment. In this paper, the time series of ET data estimated by ETWatch model which had been validated for different landscapes during the period of 2000-2010, were analyzed in spatial and temporal scales. The deviation of annual ET estimated by ETWatch with the observation ET data from eddy covariance system (EC) in the four observation stations of the basin was in the range of 5-8%. The conversion of land use type had a great impact on total water consumption across the basin due to lower variance of ET for three vegetation types. Base on the correlation analysis of climate factors and ET, there were apparent impact on ET in the upstream and midstream, but not in the downstream because of complicated human activities. The significant relations between temperature and ET (R=0.842~0.941), and between precipitation and ET (R=0.582~0.840), indicated that these two climate parameters were key influence factors on ET for grass land; The soil water storage was likely another influence factor on ET for the forest besides the temperature which had close relations with ET (R 2 =0.617~0.822). The spatial-temporal change analysis of ET and driven factors can be contributed to better understanding the eco-hydrological effect of the specific forest in Qilian Mountains.

Effects of Cryospheric Change on Alpine Hydrology: Combining a Model With Observations in the Upper Reaches of the Hei River, China

“…As shown in Figure b, the intercepted monthly precipitation accords well with the measured precipitation at the four reserved CMWR stations. Based on the eddy correlation and remote sensing data, Yan et al () reported that the average annual ET was about 342 mm between 2000 and 2013 in the UHR. During the same period, the average runoff depth was about 177 mm (Yingluoxia station in Figure ).…”

“…The average annual ET from the CBHM was about 338.6 mm (Figure a) between 1960 and 2013 in the UHR. Yan et al () gave a value of about 342 mm between 2000 and 2013 based on remote sensing data. On the point and grid cell scale, the monthly ET measured with the same two minilysimeters was close to the CBHM outputs on a 1 km scale between July 2009 and December 2013 in the Hulu watershed (Figure b).…”

Spatiotemporal Analysis of Actual Evapotranspiration and Its Causes in the Hai Basin

“…Land cover data obtain from the 2014 "Strategic Priority Research Program-Climate Change: Carbon Budget and Related Issues" of the Chinese Academy of Sciences [37,46,47], which adopt Object-based method to classify and have an overall accuracy of 86% [47].…”