Agriculture Reference
In-Depth Information
elevation model for the purpose of more effective watershed management,
and multi-scale analysis is adopted to explore the relationships between
agricultural land use intensity and water quality, and further to identify
watershed adaptive response units for every water quality parameter.
Beijing's mountainous watersheds, providing 69.9% of its surface wa-
ter resources, have played increasingly important roles in drinking water
supply and headwater conservation considering the population increase
and urban sprawl of Beijing. Moreover, land use changes in the Beijing
mountainous areas have brought about many land related problems, such
as water pollution, soil contamination and air pollution [23]. We had ad-
opted emergy analysis with principal component analysis, regression anal-
ysis and cluster classifi cation to investigate the characteristics and patterns
of agricultural land use intensity of study areas in 2000, as the baseline of
ecological monitoring and assessment [24]. However, the effects of the
agricultural land use intensity on surface water quality have not been dis-
cussed. Therefore, the objective of this study, taking the Beijing mountain-
ous area as a case, was to investigate the impacts of agricultural land use
intensity on selected physical properties of surface water quality using
multi-scale analysis for building a baseline database applicable to long-
term monitoring.
1.2 MATERIALS AND METHODS
1.2.1 STUDY AREAS
Beijing's mountainous areas, with an area of 1.04 × 10
6
ha, are located
to the west, north and northeast of Beijing. The study areas comprise a
total of five rivers, including the Yongding River, Chaobai River, Beiyun
River, Jiyun River and Daqing River (Figure 1). Mean annual precipita-
tion in the area is about 566 mm, about 60% of which falls in July and
August. The annual average evaporation is about 1,761 mm. Annual av-
erage runoff was about 1.8 × 10
9
m
3
, but this had decreased to 1.3 × 10
9
m
3
by the end of the last century as a result of climate and land use/land
cover changes.
