Abstract
Understanding the spatiotemporal characteristics of hydrological components and their impacts on vegetation are critical for comprehending hydrological, climatological, and ecological processes under environmental change and solving future water management challenges. Innovative methods need to be developed in semiarid areas to analyze the special hydrological factors in the water resource systems of these areas. Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) were applied with the normalized difference vegetation index (NDVI) data in this paper to analyze spatiotemporal changes of hydrological factors in the Xiliaohe River Basin (XRB). The results showed that precipitation (P), evapotranspiration (ET) and temperature (T) had similar seasonal change patterns at rates of 0.05 cm/yr., 0.01 cm/yr. and −0.05 °C/yr., respectively. Total water storage change (TWSC) was consistent with the change trend of soil moisture change (SMC) and showed a fluctuating trend. Groundwater change (GWC) showed a decreasing trend at a rate of −0.43 cm/yr. P and ET had a greater impact on GLDAS data (R = 0.634, P < 0.05 and R = 0.686, P < 0.01, respectively) than on other factors. GWC was more sensitive to changes in T (R = 0.570, P < 0.05). Furthermore, a lag period of 0 to 1 months was observed for the effects of P and ET on TWSC and GLDAS. NDVI showed an upward trend at a rate of 0.001 yr−1 between 2002 and 2014. A spatial distribution of NDVI was heterogeneous in the study area. ET, GLDAS and GWC in growing season limited vegetation growth and were more important than other factors in XRB. The results may contribute to an understanding of the relationships between the hydrological cycle and climate change and provide scientific support for local environmental management.
Highlights
30% of continental land area is characterized as arid and semiarid [1]
Terrestrial water storage change (TWSC) increased from 2002 to 2005 and decreased significantly from 2006 to the beginning of 2012, which led to a value that was approximately 6 cm less than the mean of the whole obtained TWSC series (Figure 2b)
The results showed that, on the spatial scale, terrestrial water storage change (TWSC) results based on Jet Propulsion Laboratory (JPL) satellite data and auxiliary data-Global Land Data Assimilation System (GLDAS = soil moisture change (SMC) + snow water equivalent change (SWEC) + total canopy water storage change (TCWSC)) values were closely related to P and T
Summary
30% of continental land area is characterized as arid and semiarid [1]. Water cycle conditions and vegetation ecosystems are fragile and sensitive in these areas [2], and increasing water demand from all kinds of water users has seriously impacted vegetation ecosystems. Distribution and growth of vegetation have changed observably in the area, which may be related to the important role of hydrological factors in a vegetation ecological environment [8,9]. It is within this context that hydrological changes and their impact on vegetation are among the key issues in semiarid areas, where water resources are scarce and the ecological environment is fragile
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