Agriculture Reference
In-Depth Information
For watershed-scale analysis, the indices of agricultural input and out-
put intensity should be translated from the municipal/town level to the
watershed level. Because there is a spatial incompatibility between the
watershed analysis unit and the municipal/town unit, the weighted val-
ues with the percentage of town's agricultural land area in the watershed
analysis unit were used as the weights to calculate the agricultural land use
intensity indices for watershed analysis unit, which is as follows:
(1)
where WUI
i
are the agricultural input and output indices for the watershed
analysis unit i, %WT
j
is the percentage of town j's agricultural land area
in a watershed analysis unit i. TUI
j
is the agricultural input and output in-
dices for town j. Therefore, the indices for watershed analysis unit i were
the weighted values with agricultural land area percentage used to refl ect
agricultural input and output intensity at every watershed scale.
1.2.5 AGRICULTURAL LAND USE INTENSITY AND WATER
QUALITY LINKAGE
The question of a relationship between agricultural land use intensity and
water quality was examined at various scales by applying multiple regres-
sion techniques considering nutrient concentrations as dependent vari-
ables and the agricultural land use intensity as explanatory variables. The
functional form of the relationship for each of these scales is as follows:
(2)
NPS
i
= f(WUI
i
)
where NPS
i
is nutrient concentration for monitoring site in question in
watershed analysis unit i, WUI
i
is equal to the indices of agricultural input
and output intensity for watershed analysis unit i.
