1. Introduction
Compared to point source pollution, nonpoint-source (NPS) pollution
is more diffuse and harder to isolate and control (Markku
et al., 2010). The NPS pollution is defined legally as any pollution
not originating from a statutory point source, which can be carried
over by rainfall and irrigation water to enter a water body dispersedly
via surface runoff. It has been well-documented that
NPS pollution, such as nutrient runoff and atmospheric deposition,
contribute significant pollutant loading to water bodies. The NPS
pollutants can cause the deterioration of water quality through
the release of suspended solids (SSs), nutrients, pesticides, fertilizer,
and other sources of inorganic and organic matter.