Detection of hydrological variations and their impacts on vegetation from multiple satellite observations in the Three-River Source Region of the Tibetan Plateau

Min Xu; Shichang Kang; Xuelong Chen; Hao Wu; Xiaoyun Wang; Zhongbo Su

doi:10.1016/j.scitotenv.2018.05.226

Detection of hydrological variations and their impacts on vegetation from multiple satellite observations in the Three-River Source Region of the Tibetan Plateau

Sci Total Environ. 2018 Oct 15:639:1220-1232. doi: 10.1016/j.scitotenv.2018.05.226. Epub 2018 May 26.

Authors

Min Xu¹, Shichang Kang², Xuelong Chen³, Hao Wu⁴, Xiaoyun Wang⁵, Zhongbo Su⁶

Affiliations

¹ State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede 7513BH, Netherlands.
² State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: shichang.kang@lzb.ac.cn.
³ CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China; Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede 7513BH, Netherlands. Electronic address: x.chen@itpcas.ac.cn.
⁴ State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China.
⁵ Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China.
⁶ Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede 7513BH, Netherlands.

PMID: 29929289
DOI: 10.1016/j.scitotenv.2018.05.226

Abstract

The Three-River Source Region (TRSR) of the Tibetan Plateau (TP) is regarded as the "Chinese water tower". Climate warming and the associated degradation of permafrost might change the water cycle and affect the alpine vegetation growth in the TRSR. However, the quantitative changes in the water budget and their impacts on the vegetation in the TRSR are poorly understood. In this study, the spatial-temporal changes in the hydrological variables and the normalized difference vegetation index (NDVI) during 2003-2014 were investigated using multiple satellite data and a remote sensing energy balance model. The results indicated that precipitation showed an increasing trend at a rate of 14.0 mm 10 a^-1, and evapotranspiration (ET) showed a slight decreasing trend. The GRACE-derived total water storage (TWS) change presented a significant increasing trend at a rate of 35.1 mm a^-1. The change in groundwater (GW) which showed an increasing trend at a rate of 18.5 mm a^-1, was estimated by water budget. The time lag of the GRACE-TWS that was influenced by precipitation was more obviously than was the GLDAS-SM (Soil Moisture) change. The vegetation in the TRSR was greening during the study period, and the accumulation of the NDVI increased rapidly after 2008. The effect of total TWS and GLDAS-SM on vegetation was considerably more than that the effects of other factors in this region. It was concluded that the hydrological cycle had obviously changed and that more soil water was transferred into the GW since the aquiclude changed due to climate warming. The increasing area and number of lakes and the thickening of the active layer in the permafrost area led to the greater infiltration of surface water into the groundwater, which resulted in increased water storage.

Keywords: Hydrological variations; Normalized difference vegetation index (NDVI); Three-River Source Region; Tibetan Plateau; Water budget.