**1.2 Importance of biologic index**

The use of biological indicators to assess the health of the river ecosystem has become increasingly important because the function of life, biodiversity, population density, human settlement, and the activity of aquatic organisms are affected by all changes in the water ecosystem. River life decisions can be made based on biodiversity and quantity. Many aquatic species such as fish [12, 13], algae [14], plankton [15], and benthic macroinvertebrates [16, 17] are common biologic indicators of water pollution and are used in biotic reliability for the aquatic ecosystem [18–21]. The types of indicators are those taxes that are known to be more sensitive to certain environmental factors so that changes that occur or in large quantities can directly reflect local change [22]. The usage of biomonitoring techniques in river ecosystems have many advantages compared to physiochemical techniques [23]. Freshwater organisms play an important role in the continuously monitoring water quality and pollutants that enter at different time intervals. In most cases, the disorder occurs during at least one stage (egg, larva, caterpillar, adult) of the invertebrate animal life cycle. If this category is affected by the disruption, changes will be seen in the community structure if sampled over time [24]. Macroinvertebrates are also sensitive to stress; it can be natural or humanbased. This change will lead to an impaired community. The aquatic insects show the effect of point and non-point contaminants, physical habitat alteration, and pollutant accumulation over the life cycle [25].

*Evaluation of Water Quality Using Physicochemical Parameters and Aquatic Insects Diversity DOI: http://dx.doi.org/10.5772/intechopen.108423*
