Yanjun Shen: Agricultural Hydrology and Water Resources

Evaluating the Effects of Land Use Change on Evapotranspiration in Hai River Basin, China

Yusheng Shi, Yanjun Shen, Min Liu, Yongqing Qi Yucui Zhang and Zaijian Yuan

Human-induced land use/cover change has deep implications on hydrological cycle and processes, which has caused wide attentions all over the world. Since 1990s, IGBP and IHDP had launched a series of projects on the changes of hydrological cycle and processes related to human activities with a consensus of hydrological cycle under changing environments as a new frontier and hotspot. Hai River Basin (HRB) has experienceda fast urbanization process under intensive human activities in 1990s and associated land use type went through drastic changes, which arouse great changes on evapotranspiration as well. Based on remote sensing and GIS, we quantified the land use change between 1990 and 2000. The result showed land use of HRB has undergone great changes characterized by obvious enlargement of built-up and residential land. A net gain of 3650.6 km2 for built-up land use was detected from 1990 to 2000, accounting for an increase of 14.3% of the total area. This significant increase of built-up land was traced mostly converted from cropland, which demonstrated the most obvious land use change in HRB.

The change of evapotranspiration from 1990 to 2000 showed it had a decreasing

trend across HRB under the influence of climate change and land use change (Figure 2.

Left). In parts of northern mountain areas, evapotranspiration showed an increasing

trend, the same phenomenon was also observed in parts of central plain with sufficient

irrigation. When only considering the effects of land use change, it was found that the

evapotranspiration displayed obvious increase in northern and western mountain areas,

and also in irrigation areas in plains, while southern areas had minor loss of evapotranspiration

(Figure 2. Right).