This line graph describes information on international (shows/ depicts) the worldwide change in water consumption by the Agricultural, Industrial and Domestic sectors from 1900 to 2000. The other chart provides compares the water consumption of Brazil to the Democratic Republic of Congo in 2000. 
Overall, it can be seen that all three sectors of water use experienced an upward trend throughout the whole time frame. The Industrial and Domestic use were the smallest figure during 50 years from 1900 the 1950 at well under 500km3 and only rose slightly during these years. After 1950, the amount of water used by the Agricultural sector increased rapidly from 1000km3 in 1950 to 3000km3 in 2000. 
As for water consumption chart of Brazil and Congo in 2000, it is clear that Brazil used huge amount of waters for irrigation with 26,500km2 while Congo spent at only has 100km2 on of irrigated land. In addition, the figure of water consumption per person in Brazil was far higher than Congo by the rates a ratio of 359m3 and 8m3

Notes:

1. Graphs don’t describe, they “show” or “depict”
2. International means “between nations”, while “worldwide/global” means “the world as a whole”
3. The other chart is a “comparison”
4. If you say “sectors of water use” it means there are different types of water use, not different sectors are using water.
5. You don’t need to say “during 50 years” because you write “from 1900 to 1950”
6. If you are saying how much something has increased, you need to have the starting point and the ending point.  So we need to say “1000km3 in 1950”.
7. Irrigation is a thing.  You can’t “spend” on irrigation. “km3” is an area, not a volume.
8. “Figure” is a point on a graph.  You are saying the actual amount used by people is higher.
9. A rate is how much.  A ratio is a comparison.