Assessment of Environmental Water Requirement Allocation in Anthropogenic Rivers with a Hydropower Dam Using Hydrologically Based Methods—Case Study

Hossein Hamidifar,Paweł M Rowiński,Farzaneh Akbari

doi:10.3390/w14060893

Hossein Hamidifar, Paweł M Rowiński + Show 1 more

Open Access

https://doi.org/10.3390/w14060893

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Abstract

Anthropogenic activities such as damming have caused an alteration in the natural flow regime in many rivers around the world. In this study, the role of constructing a hydroelectric dam on the natural flow regime of the Kor River, Iran, is investigated. Nine different methods, which fall into the category of hydrological methods, were used to determine the environmental water requirement (EWR) of the Kor River. In addition, two indices are introduced to evaluate the environmental flow allocation in anthropogenic rivers. The results show that although the supply of environmental flow in some months is in relatively acceptable conditions on average, there is a deficiency in the allocation of EWR in the range of 1.92–30.2% in the spawning period of the dominant fish species. The proposed indicators can provide a general picture of the status of environmental flow allocation in rivers where little ecological data is available and the hydrological regime has changed due to human activities, particularly in rivers with hydropower plants. Moreover, after the construction of the dam, no major floods have occurred in the river, which has led to the loss of the morpho-ecological balance in the river and disruption of the natural state of habitats. Therefore, the negative impact of dam construction on the environmental conditions of the river should be considered in the active management of the dam outlets.

Highlights

The main objectives of the current study are: (i) comparison of the differences in environmental water requirement using nine hydrology-based EWR determination methods applied to a study site; (ii) investigating the effect of the construction of Mollasadra Dam on changes in the flow parameters of the Kor River by the Range of Variability Approach; and (iii) evaluating the adequacy of the allocated flow in the river to meet the EWR after the dam construction
The results of Tessman, Smakhtin, flow duration indices, 7Q10, Flow Duration Curves (FDC) shifting, and Range of Variability Approach (RVA) methods show that there are some levels of deficiency in the minimum EWR, i.e., negative values of AEWR
Nine different methods including traditional and modified Tennant, Tessman, Flow duration indices, Smakhtin, low-flow indices, FDC shifting, desktop storage model (DRM), and range of variability approach (RVA), which fall into the category of hydrological methods, were used to determine the EWR

Summary

Introduction

In most parts of the world, the construction of dams and over-exploitation of water resources, such as river water diversion for agricultural, urban, and industrial purposes, have affected the main variables of river water [1]. In many cases, these interferences can have a negative impact on the hydrological and ecological services provided by ecosystems, making them vulnerable to humans and other organisms dependent on these services [2–4]. The change in the hydrological regime affects a number of other processes taking place in the downstream part of the river channel, including the transformation of its geomorphological features, which is, for example, evident in the study of the impact of the Włocławek Reservoir on the hydrological regime of the lower Vistula, Poland [8]. Among different types of dams, hydropower dams have a considerable impact on the release in the river [12,13]

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