Southern Research Station

Title: Watershed evapotranspiration increased due to changes in vegetation composition and structure under a subtropical climate

Author: Sun, Ge; Zuo, Changqing; Liu, Shiyu; Liu, Mingliang; McNulty, Steven G; Vose, James M.

Date: 2008

Source: Journal of the American Water Resource Association, Vol. 44(5): 1164-1175

Description: Natural forests in southern China have been severely logged due to high human demand for timber, food, and fuels during the past century, but are recovering in the past decade. The objective of this study was to investigate how vegetation cover changes in composition and structure affected the water budgets of a 9.6-km₂ Dakeng watershed located in a humid subtropical mountainous region in southern China. We analyzed 27 years (i.e., 1967-1993) of streamflow and climate data and associated vegetation cover change in the watershed. Land use / land cover census and Normalized Difference of Vegetation Index (NDVI) data derived from remote sensing were used to construct historic land cover change patterns. We found that over the period of record, annual streamflow (Q) and runoff / precipitation ratio did not change significantly, nor did the climatic variables, including air temperature, HamonÂ’s potential evapotranspiration (ET), pan evaporation, sunshine hours, and radiation. However, annual ET estimated as the differences between P and Q showed a statistically significant increasing trend. Overall, the NDVI of the watershed had a significant increasing trend in the peak spring growing season. This study concluded that watershed ecosystem ET increased as the vegetation cover shifted from low stock forests to shrub and grasslands that had higher ET rates. A conceptual model was developed for the study watershed to describe the vegetation cover-streamflow relationships during a 50-year time frame. This paper highlighted the importance of eco-physiologically based studies in understanding transitory, nonstationary effects of deforestation or forestation on watershed water balances.

Keywords: evapotranspiration, forest hydrology, normalized difference of vegetation index, Southern China, streamflow

View and Print this Publication (798 KB)

Publication Notes: 

• We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
• This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

 Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

Citation

Sun, Ge; Zuo, Changqing; Liu, Shiyu; Liu, Mingliang; McNulty, Steven G; Vose, James M.  2008.  Watershed evapotranspiration increased due to changes in vegetation composition and structure under a subtropical climate.   Journal of the American Water Resource Association, Vol. 44(5): 1164-1175