The fieldtrip on the Kam Tin North River Basin was carried out from 9:55 a.m. to 12:05p.m. on the 15th March, 2013. Sites 1-6 are located along the river from tributaries in upper stream to the main channel in lower stream, in which data related to water quality of river was collected. Depending on geological factors, the water quality of Kam Tin North River varied greatly from site 1 to site 6. Results and explanations of sites 1-6 will be reported respectively as follows.
As this site is located at the Kadoorie Institute, data is collected in classic step-pool upland stream. The land use nearby is woodland, and the environment is mainly shrub and trees. Vegetations help filtering water by trapping sand and fines by roots, also it absorbs most of the nutrients to grow and increase the nitrogen level. Also, it reduces sediments in river stream. Hence, the conductivity level shown in Figure 2 and suspended sediment level shown in Figure 4 is the lowest among all sites. With the lowest amount of phosphate, nitrate and ammonical, there is no threat of algae at this site. Besides, rock types are mainly cobble and bedrock which is considered large sized sediments. As a result, water is very clear and clean at site 1 and no pollution problem was found so the water quality is relatively high.
This site locates in the upper stream of the river. The dominant land uses at site 2 are shrub land and woodland. Thus, the situation is similar to site 1 that water is also clear. There are many boulders and trees nearby blocked part of the sunlight to the water. Therefore, temperature recorded at site 2 is the lowest, only 18.5℃. (Figure 3) It is known that the colder the water, the more oxygen can be held in water. Therefore, the dissolved oxygen is not high, for which it is suitable for aquatic biota. Pollution problem could not be found in this site.
According to observation, land use near site 3 is an open storage area. Also,...