Agriculture Reference
In-Depth Information
at the watershed scales of Zone 5. The regression equation between agri-
cultural land use intensity and permanganate index in the Zone 5 model,
with the value 0.452 of R
2
and the level 0.001 of statistical signifi cance,
is as follows:
ln(COD
Mn
) = 0.745 + 0.514WI-IPC
3
+ 0.052WI-IPC
4
(4)
In the regression model of permanganate index, the two input intensi-
ties of pesticides and agricultural plastic mulch and organic manure in-
side the contributing zone (Zone 5) both have the positive impact on the
permanganate level downstream. Therefore, the input of pesticides and
agricultural plastic mulch is considered as the larger contributor than the
organic manure input.
1.4 DISCUSSION AND CONCLUSIONS
1.4.1 AGRICULTURAL INPUT INTENSITY AND SURFACE
WATER QUALITY RISK
Land use/land cover management, particularly high-input agriculture, is
considered to be an important source of pollution export from catchments
and frequently has been identified as a major contributor of surface wa-
ter pollution [26]. The above results and analysis provide insight into the
linkages between agricultural land use intensity and regional surface water
quality. For the Beijing mountainous study area, several groups of agricul-
tural input affecting surface water quality were identified during the year
2000. The results indicated that the explanatory variables behind the vari-
ous water quality indexes were quite different at the respective significant
watershed scales. The view that nitrate may be a useful general indicator
of intensive land use was supported by previous work by Hunt et al [27].
As in Hunt [27], nitrate in particular can be considered as a useful indica-
tor of intensive natural factors and agricultural chemical fertilizer input
at the significant watershed scale in the Beijing mountainous areas. The
