Qualitative Modeling for Managing Water Allocation in Rivers

Evaluating the response of rivers to natural changes and man-made manipulations are of great importance in managing river water quality. The main purpose of this study is to evaluate the negative effects of quantitative management without qualitative management of river flow. In this regard, by simulating water quality in river exploitation scenarios based on environmental policies, including minimum flow allocation, reduction of flow quality from aquaculture standards, taking into account the quality factors and pollution caused by the development of marginal urban communities, will be discussed.

The present study, which should be omitted was conducted on the Azadrud River in the Sarvabad region of Kurdistan Province. In this regard, by measuring quantitative and qualitative parameters in two monthly periods, the QUAL2KW quality model was calibrated and validated. In the first part of the study, the quality of the river along 22 km was simulated by changing the flow rate based on flow allocation scenarios in the Tenant method, and in the second part, the values of qualitative parameters in different flow management scenarios were compared with the accepted standard values for aquaculture (fish).

Based on the results, while the minimum environmental discharge according to the Tenant method for the studied river is 1.1 m3/sec, the critical quality discharge for March and April were estimated at 7.7 and 10 m3/sec, respectively. The study showed that the poor tenant scenario is not suitable for allocating the minimum environmental flow to meet the quality requirements of the river at all. 

The results showed that the conventional flow allocation method, i.e., without considering the quality conditions of the river, is not suitable and can cause serious damage to the environmental conditions of the river. This study showed that ignoring the quality conditions at the time of flow allocation causes the ecological health of the stream to be lost and the river to not meet the required standard for aquaculture.