Geography Reference
In-Depth Information
Table 5.5 Statistics of heat flux and radiation (measured in W/m
2
) of different land covers
land cover types
Latent heat flux
Downward shortwave radiation
Cropland and pasture
24.9
279.6
Grassland
25.3
284.0
Forestry area
36.0
289.9
Urban area
15.0
295.0
The socioeconomic development and rapid urbanization mean that more lands are
converted to urban area. During the period of 2010-2050, there will be an increase of
5.3 9 10
3
km
2
for urban area in the semiarid grassland area of China under the REG
scenario, most of which is converted from cropland. Correspondingly, there is less
cropland converted to grassland or forestry area. Compared to the CES scenario, the
grassland will increase only by 23.3 9 10
3
km
2
during the period of 2010-2030,
while with an increase of 4.2 % in the period of 2030-2050. The expansion of
grassland is mostly concentrated in the eastern part of Loess Plateau (Fig.
5.6
). On
contrary, most of the cropland is located in the southern part of the study area
including the central and southern Shanxi Province, southern Shanxi Province, and
southeastern Gansu Province. It is notable that there are more water resources in the
eastern and southern part of study area, which is beneficial for forest growing. Under
the REG scenario, some areas of grasslands are degraded to bare land or are turned
into cropland in the western part of the semiarid grassland area of China.
5.2.5 Effects of Land Cover Conversion on Energy Balance
in the Semiarid Grassland Area of China
This study simulates the latent heat flux and downward shortwave radiation by the
WRF model, and then summarizes the latent heat flux and downward shortwave
radiation on different types of land cover. The results indicate that the energy
fluxes vary with the land covers, so the land cover conversion will produce dif-
ferent effects on regional environment and climate, however, the extent of their
impacts and sensitive region has obvious temporal and spatial disparity. In addi-
tion, the statistical results show that forestry area has highest latent heat flux with
36.0 W/m
2
, while urban area has relative low latent heat flux which is 15.0 W/m
2
(Table
5.5
). As for the downward shortwave radiation, the urban area is highest
with 295.0 W/m
2
, while it is lowest for cropland and pasture.
5.2.5.1 Latent Heat Flux
The simulation results show that the barren or sparsely vegetated land in the
western parts of Inner Mongolia Autonomous Region and northern Shaanxi
Province has lower latent heat flux, while it is higher in the southern areas which
