Mapping a pollution index for the transboundary Red River Valley, Asia, 2009–2011

Figures & data

Figure 1. Map of the study area.

Table 1. Codes, types and interpretation keys of pollution sources.

Pollution source	Code	Type	Interpretation key
Industrial district	1	polygon
Factory	2	point
Mine	3	point
Tailing reservoir	4	point
Aquafarm	5	point

Figure 2. Example of visual interpretation based on Google Earth.

Table 2. Scoring system of pollution sources.

Type of pollution source	Area (km^2)	Score
Industrial district	<0.2	5
	0.2–0.5	7
	0.5–1.0	10
	1.0–2.5	20
	2.5–5.0	30
	>5.0	40
Factory	/	2
Mine	/	4
Tailing reservoir	/	4
Aquafarm	/	3

Figure 3. Spatial distributions of derived pollution sources from Google Earth.

Figure 4. Pollution index map of Red River Valley.