Question

How a stream, river, or any liquid can be tested using random sampling furthermore, without bias. 

Answer 1

1. http://www.mdpi.com/2072-4292/7/12/15817/htm

Sampling methods used to validate the coarse-resolution fractional vegetation cover (FVC) product in the Heihe River Basin, where the patterns of spatial variations in and between land cover types vary significantly in the different growth stages of vegetation.

Sampling methods, such as simple random sampling, systematic sampling and stratified sampling, have been applied to the validation of remote sensing products and other applications. The advantage of these classical sampling methods is that they require minimal a priori information about the population and are easy to use. Thus, they are commonly applied in different domains, including both spatial and non-spatial data analysis.

Three additional sampling methods, namely, simple random sampling,is also implemented for comparison purposes. This study attempts to compare the sampling methods on determining the samples for FVC product validation at a coarse scale from the perspective of expecting temporal as well as spatial variation.

EXAMPLE:-

1. First, for a given sample number m, m initial spatial samples are generated using a simple random sampling method.

2.sample locations are adjusted individually to generate new spatial configurations of samples.

3.the second step is repeated with a Monte Carlo simulation algorithm to find the sample configuration with the smallest theoretical estimated error variance.

METHOD 2

SAMPLING EQUIPMENT

EXAMPLE:-

The standard samplers used in the NAWQA program for collecting water samples include the DH-81, D-77 TM, D-77 Bag, and weighted- and open-bottle samplers with Teflon or glass components. These samplers will collect representative water-chemistry samples in most stream environments