关键词: 蒸散发（ET）, 时空特征, 驱动因素, 土地利用类型, 气温, 降水, 海河流域, MOD16

Abstract:

Evapotranspiration (ET) is the key element linking surface water balance and hydrological energy cycle. Studying the spatiotemporal variations of ET and its driving climatic factors is of great significance for clarifying the relationship between water resources and climate change. Based on the MOD16/ET dataset, this paper quantitatively analyzed the temporal and spatial variations of ET in the Haihe River Basin from 2000 to 2014. Based on the long-term observation data of air temperature and precipitation, the correlation analysis method was used to quantitatively explore the relationships between ET and various climatic factors. Results show: (1) The ET of the Haihe River Basin from 2000 to 2014 showed a relatively significant spatial distribution pattern, with higher values in the north and south, and lower values in the northwest and middle east. Distribution of the inter-annual ETs of different land use types showed a decreasing pattern for forest land, grassland, cultivated land, and other types. (2) The annual average ET of the Haihe River Basin from 2000 to 2014 ranged from 371.96 mm/a to 441.29 mm/a, with an average of 398.69 mm/a. The average relative change rate was -0.41%, which showed a downward trend. (3) The ET as well as climatic factors of air temperature and precipitation in 2000-2014 showed a uni-modal periodic variation trend, and the monthly ET showed a single peak trend within the year. (4) The correlation between ET and precipitation/air temperature in spring and autumn was significantly higher than other seasons, with their average correlation coefficients being -0.17 and 0.37, respectively. This indicates that ET is positively related with precipitation and negatively related with air temperature. (5) The majority types of ET changes in the Haihe River Basin were precipitation driven as well as precipitation and air temperature combination driven. (6) The climate factor driving mode of cultivated land ET change in Haihe River Basin was mainly precipitation and temperature; the driving mode of forest land and grassland was mainly air temperature and precipitation, while the drivers of other land-use types were mainly other factors. Our findings provide scientific guidance for water resource development management and regional climate regulation in the Haihe River Basin.

Key words: Evapotranspiration (ET), spatio-temporal characteristics, driving factors, land use types, air temperature, precipitation, Haihe River Basin, MOD16