Dissecting the Mutual Response of Potential Evapotranspiration with Vegetation Cover/Land Use over Heilongjiang River Basin, China

Abstract

Spatiotemporal changes in potential evapotranspiration (PET) are important referential data for monitoring the variation in ecohydrology under climate change. As the key area of agricultural/forestry reserves and trade, research on the interactions between vegetation cover and land use with accurate PET among the Heilongjiang River basin, China is vital for the sustainability of this cross-border region. To obtain high-suitability PET estimation based on the proven Penman–Monteith (PM) principle, two schemes were adopted using 36-year in situ meteorological data (1984–2019) and derived remote-sensing product MOD16A2 from 2001 to 2019. At meteorological sites with heterogeneous underlying surfaces, the coefficients of the evaluation factors between MOD_PET and the referrable observations were better. This suggests that remotely sensed estimation was preferentially chosen as the input to study the mutual responses. The results indicated that the annual PET and fractional vegetation cover (FVC) changes differed significantly depending on the land use. The proportions of PET according to equal intervals initially increased and then decreased with increasing vegetation coverage, and changing trends indicated a negative correlation. The strongest correlations appeared in the middle to northern sub-basins, which were affected by their distinctive climatic characteristics. The response of PET was reverse-related with changes in the area of each selected land type, but could change with the expected climatic conditions.