A. IF B. UNLESS C. WHEN D. IN CASEREAD THE FOLLOWING PASSAGE AND A...
23. A. If
B. Unless
C. When
D. In case
Read the following passage and answer the question
Flood stands amongest the most devastating natural catastrophes. Almost everyone is
well aware of its negative impacts on human such as loss of human life, damage to
property, destruction of crops, loss of live stocks, and deterioration of health conditions
owing to waterborne diseases.
However, flood can also have some positive impacts on the environment. In many
natural systems, floods play the key role in maintaining the ecosystem functions and
biodiversity. They link the river with the land surrounding it, recharge ground water
systems and fill wetlands. Moreover, floodwater often carries both sediment and nutrients,
so it helps enrich the land. For many species, flood trigger breeding events, migration,
and dispesal. The environmental benefits of flooding can also help the economy through
things such as increased fish production, recharge of groundwater resources, and
maintenance of recreational environments.
While cycling of sediments and nutrients is essential to a healthy ecosystem, too much
sediment and nutrient in a waterway lowers the downstream water quality. Other negative
effects include loss of habitat, dispersal of weed species and the release of pollutants such
as chemicals, heavy metals and debris. These can degrade aquatic habitats, lower water
quality, reduce coastal production, and contaminate coastal food resources.