**1. Introduction**

Hydropower is the most common renewable energy source for electricity production. Small-scale hydropower projects (SHPs) play an important role in generating electricity and have been established in 166 countries [1], of which China had ranked first with over 47,498 SHPs by the end of 2017. SHPs in China are defined as having an installed capacity under 50 MW, although there is no internationally agreed definition [2]. The Chinese governmen<sup>t</sup> encourages the development of renewable energy, such as hydropower and wind power, from which all electricity is purchased by grid companies. There is no unified feed-in tariff for SHPs in China, and each province has the right to set its benchmark price, which is based on SHP development costs and the average purchasing price of the provincial electricity grid company [3].

In the last decade, more attention has been paid to the ecological impacts induced by SHPs, such as hydrological alteration [4–6], river connectivity fragmentation [7], habitat losses [8], and changes in species composition [9,10]. Research has also highlighted the cumulative impacts of SHPs to gain a better understanding of their environmental

**Citation:** Ruan, Q.; Wang, F.; Cao, W. Conflicts in Implementing Environmental Flows for Small-Scale Hydropower Projects and Their Potential Solutions—A Case from Fujian Province, China. *Water* **2021**, *13*, 2461. https://doi.org/10.3390/ w13182461

Academic Editors: Athanasios Loukas and Luis Garrote

Received: 8 July 2021 Accepted: 31 August 2021 Published: 7 September 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

consequences [11–13]. One important impact is the alteration in natural flow regimes, including river flow depletion [14], which has been proven to be related to the type of hydropower [15–17]. In this study, SHPs were grouped into three categories, namely diversion-type, barrier-type, and mixed-type projects. Both diversion-type and mixed-type projects transfer flow away from natural watercourses through channels or pipelines [18]. Barrier-type projects can be further classified into run-of-river projects and reservoir-type projects depending on their mode of storage. Diversion-type projects are most likely to dry up flows, especially during the dry season [19,20].

Environmental flows (E-flows) refer to discharge volumes that should remain in the river channel [21] to sustain freshwater ecosystem health and human well-being [22]. For the last 50 years, numerous studies have assessed E-flows for ecological health [23–28]. Not until this century have E-flows gradually been incorporated into legislation and regulation practices in many countries [29]. However, in many cases, E-flows are still at the stage of discussion and policy enactment [30], while their implementation faces political, economic, technical, and social challenges [31,32]. We stress that there is a disconnection between booming E-flows science and practice. Currently, there is insufficient work that integrates practice into E-flows literature. Of the existing narratives, there exists a lacuna in mitigating the conflicts in E-flows implementation for SHPs, especially those that incur losses, and the issue of "willingness to pay" [33].

In China, to operate SHPs, one needs an environmental impact assessment and electric power business license. However, E-flows were not involved in environmental impact assessment until the first official requirement of E-flows was stated in 2006 [33]. Additionally, due to neglect of the environmental impacts of SHPs, the regulation only proved effective for large-scale hydropower projects. As the first province in China to enforce E-flows implementation for SHPs, the Fujian provincial governmen<sup>t</sup> made little progress in implementation until the Jiulong River experienced algal blooming in 2009. This problem was finally solved by opening the sluice gates of all the upper stream hydropower projects. In addition, there are more than 6000 licensed SHPs in Fujian Province [34], including diversion-type (76.7%), barrier-type (11.8%), and mixed-type (11.3%). Crucially, most SHPs in Fujian Province lack the necessary facilities for releasing E-flows because the majority (99.7%) of SHPs had been established before the first Chinese regulation of E-flows was issued.

Discharge and flow velocity are critical factors affecting algal blooming [35,36], which occurs more frequently in rivers with more hydropower projects in Fujian Province. To prevent algal blooming, the Provincial Department of Environmental Protection has required the SHPs of 12 primary rivers to release E-flows and install online monitoring facilities in 2009 [37]. Implementation has involved two different methods, with either "10% of Mean Annual Flow" (10%MAF) [38] or "90-percent exceedance probability of the average flow rate in the driest month based on statistics of monthly mean flows at least 10 years" (Qdm90) as the minimum target [38]. Limited by hydrological data, 10%MAF was used for SHPs in rivers with a drainage area of <500 km2, which account for 85% of the total SHPs [39], while Qdm90 was adopted by SHPs on the main channels with a drainage area >500 km<sup>2</sup> [40]. However, at the end of 2010, only 28% of the 415 required SHPs had been installed with monitoring facilities [41].

In response to those limitations of the existing literature and urgen<sup>t</sup> demand of releasing E-flows, here, we provide a case study in support of recommendations to facilitate the implementation of E-flows for SHPs. This study is the first known attempt to gather perspectives on E-flows, SHPs, and willingness to pay from three interest groups based on questionnaires and interviews. The objective of the study was to determine the key conflicts in implementing E-flows and to propose potential solutions. By reviewing the literature [42–44], three factors were selected as the main obstacles, namely economics, stakeholders' skepticism, and technologies. Here, we define economic conflicts as economic losses induced by retro-fitting dams and releasing E-flows; stakeholders' skepticism encompasses differences in opinion on whether SHPs are green and the necessity of implementing E-flows; and technical difficulties that include the engineering feasibility of retrofit dams for releasing E-flows. We hypothesized that the threat of economic losses would contribute the most to these potential conflicts, as has been previously suggested in the literature [31,44,45]. We also examine stakeholder perspectives on who should pay for incurred losses and their willingness to pay. Specifically, we aimed to (1) explore the environmental impacts of SHPs in Fujian Province, (2) analyze the difficulties and stakeholder conflicts when implementing E-flows, and (3) examine the current mitigation measures and propose potential solutions.

### **2. Materials and Methods**
