where MPL is the maximum allowable solid-state phosphorous loss
(kg). Runoff from agricultural land plays a large role in increasing
the organic waste found in surface water. When excessive fertilizers
are applied to agricultural lands, these superfluous nutrients join the
runoff from the fields. Soil and nutrients from the fields can also be
lost due to heavy rain falls and rainstorms. For each subarea, total
dissolved nitrogen losses of normal and wet seasons should not exceed
the maximum dissolved nitrogen loss. Similarly, loss of dissolved
phosphorous in runoff was the main part of phosphorus
loss. Since the maximum dissolved nitrogen and phosphorus can
hardly be presented by a deterministic value, they are valued by
fuzzy sets. A questionnaire survey and experimental observations
are conducted to obtain the data of dissolved nitrogen and phosphorous
losses, which are also represented by fuzzy sets. Very detailed
information regarding data collection and processing can be seen
from a report submitted to UNDP (Huang et al., 2006). With a given
credibility threshold level, the annual dissolved nitrogen losses can
be constrained by: