Studies of qualitative indices and the proposal of necessary protection measures for protected Haraz River

This study was conducted to investigate the health status of the Haraz River ecosystem as one of the most important protected rivers in Iran. Sampling was done in 2020 and 2021 from 14 stations along the river. Identification of macrobenthos and calculation of Z index was performed along with Quality status, determination of toxicity, measurement of PAHs and statistical analysis of data. Based on the results, IRWQIsc was decreasing towards the downstream, except for the branches. IRWQIst fluctuated and generally decreased from upstream to downstream. The Z index had the highest value (4) in the downstream stations. In terms of self-purification, the river was in oligosaprobe, betamzosaprobe, alphamzosaprobe and polysaprobe classes. Upstream was more favorable than downstream and the cold season was more suitable than the warm season. Maps were prepared based on saprobe, integration of self-purification, BOD and land use of the region. The results of the analysis showed the important role of human activities, especially rural and garden uses, and in the next stage, roads, in the quality of river water. From upstream to downstream, the number of polluting sources has increased and they have shown their role. The increase in the density of rural areas, gardens, and fish farms has caused an increase in BOD and Z index. Therefore, it is necessary to follow up and carry out the treatment of sewage, development of agricultural system standards and supervision of the use of underground water along with dealing with the violators in order to protect the river.