The success of the sampling method is highly dependent on the equipment for sampling, a technique or way of making, implementation and management as well as the improvement of laboratory analysis. more than 50% of the invalidity of the data analysis of water kuallitas is affected by the sampling technique is not appropriate.
a. Determining the location of sampling
The location of sampling can be done on surface water and groundwater. Sampling of surface water include rivers, lakes, reservoirs, swamps, and other puddle Determination of water quality in the drainage area of the river based on:
- Natural water sources, namely the location of the place yet or are still slightly polluted;
- Contaminated water sources, namely the location of the place has changed or downstream sources of pollution;
- Water sources are used, ie tapping a location on the utilization of water resources.
While monitoring the water quality in the lake / reservoir based on:
- Where the entry of the river into the lake / reservoir
- In the middle of the lake / reservoir
- Location tapping of water for utilization
- Where the discharge of water in the lake / reservoir
b. Determining the location of sampling river water
The initial step in determining the location of water sampling sungaiadalah know the state of the geography of the river and the activities around the watershed. In general, the river water sampling locations include:
- Upstream areas or natural water source, the location of which has not been contaminated. This location contribute to the identification of the origin or baseline condition of the water sistemtata
- Area utilization of river water, which is the location where river water is used as raw material for drinking water, water for recreation, industry, fisheries, agriculture, and others. The goal is to determine the quality of the water before it is affected by an activity
- Areas potentially contaminated, the location of which changes the quality of water by industrial activities, agriculture, domestic, and so on. This location was chosen to determine the relationship between these activities and the effect of a decrease in river water quality
- Regional meeting of two rivers or the location of the entry of tributaries. This location is chosen if there are activities that have an influence on river water quality deterioration
- Downstream or estuaries, the tidal area which is a meeting between river water and seawater. aim to determine the overall quality of the river water. If the data in the test results were compared with data downstream to upstream areas, the evaluation may be material river water management policies in an integrated manner.
Especially for the confluence of two rivers or the entry of a tributary, the sampling locations are in areas where the water in the two rivers were thought to have been mixed perfectly. To find necessary to test the homogeneity of the river water. Homogeneity test is done by taking multiple samples across the width of the river and at certain depths. The test parameters are temperature, acidity, or pH, dissolved oxygen or DO, and electrical conductivity (EC).
If the test results at some point parameter is not much different, ie less than 10%, it can be concluded that there has been a perfect blending between the two river water. Table 11 illustrates the approximate distance perfect mixing for determining the location of sampling.