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Review

Effectiveness of Small Hydropower Plants Dismantling in the Chishui River Watershed and Recommendations for Follow-Up Studies

by
Wenzhuo Gao
1,2,
Zhigang Wang
2,3,*,
Ke Wang
2,3,
Xianxun Wang
1,*,
Xiao Li
2,3 and
Qunli Jiang
4
1
Hubei Key Laboratory of Petroleum Geochemistry and Environment, Yangtze University, Wuhan 430100, China
2
Changjiang River Scientific Research Institute, Changjiang Water Resources Commission, Wuhan 430010, China
3
Observation and Research Station for Small and Medium-Sized Rivers and Flash Flood Disasters in Mountains of Southwest China, Ministry of Water Resources, Wuhan 430010, China
4
Water Affairs Bureau, Chishui 564700, China
*
Authors to whom correspondence should be addressed.
Water 2025, 17(19), 2909; https://doi.org/10.3390/w17192909
Submission received: 1 September 2025 / Revised: 1 October 2025 / Accepted: 3 October 2025 / Published: 9 October 2025
(This article belongs to the Section Water Resources Management, Policy and Governance)
Browse Figures
Versions Notes

Abstract

With the characteristic of “decentralized distribution and local power supply”, small hydropower (SHP) in China has become a core means of solving the problem of insufficient power supply in rural and remote mountainous areas, effectively promoting the improvement of local livelihoods. However, for a long time, SHP has had many problems, such as irrational development, old equipment, and poor economic efficiency, resulting in some rivers with connectivity loss and reduced biodiversity, etc. The Chishui River Watershed is an ecologically valuable river in the upper reaches of the Yangtze River. As an important habitat for rare fish in the upper reaches of the Yangtze River and the only large-scale tributary that maintains a natural flow pattern, the SHP plants’ dismantling and ecological restoration practices in the Chishui River Watershed can set a model for regional sustainable development. This paper adopts the methods of literature review, field research, and case study analysis, combined with the comparison of ecological conditions before and after the dismantling, to systematically analyze the effectiveness and challenges of SHP rectification in the Chishui River Watershed. The study found that after dismantling 88.2% of SHP plants in ecologically sensitive areas, the number of fish species upstream and downstream of the original dam site increased by about 6.67% and 70%, respectively; the natural hydrological connectivity has been restored to the downstream of the Tongzi River, the Gulin River and other rivers, but there are short-term problems such as sediment underflow, increased economic pressure, and the gap of alternative energy sources; the retained power stations have achieved the success and challenges of power generation and ecological management ecological flow control and comprehensive utilization, achieving a balance between power generation and ecological protection. Based on the above findings, the author proposes dynamic monitoring and interdisciplinary tracking research to fill the gap of systematic data support and long-term effect research in the SHP exit mechanism, and the results can provide a reference for the green transition of SHP.

1. Introduction

Small hydropower (SHP) plays an important role globally. The World Small Hydropower Development Report 2022 compiles data from 129 countries and territories across five continents, reporting 6249 existing SHP plants with a combined installed capacity of 24,436 MW and 8860 planned or potential projects totaling 34,208 MW (Figure 1). Of the existing SHP plants, the majority are located in Northern America, while Southern Asia has the highest number of potential projects (Figure 2) [1]. Importantly, definitions of SHP differ across countries, and local regulatory and legal frameworks markedly affect development patterns, incentives, and barriers. Positioning China’s extensive SHP stock and recent policy-driven reforms within this broader spatial and regulatory context clarifies both China’s contribution to global SHP and the distinctive governance and ecological challenges it faces.
China is the leading country in SHP development, contributing approximately 51% to the total global installed capacity [2]. About 47,000 SHP plants had been built in China by the end of 2016, with a total installed capacity of 77.91 million kW [3]. For a long time, SHP has undertaken the important mission of optimizing the energy structure and promoting regional coordinated development, effectively alleviating the phenomenon of power shortage in rural and remote mountainous areas. At the same time, it has also made a great contribution to poverty alleviation, improving people’s well-being, and activating the county economy [4]. Nevertheless, there is irrational development, old equipment, and poor economic efficiency, and other problems, resulting in ecological crises such as river outflow and ecological crises [5]. With the improvement of China’s energy structure and the requirements of “ecological priority and green development” (place ecological protection at the forefront of development decisions and promote economic and social progress through low-carbon, resource-efficient, and sustainable approaches to ensure the integrity and long-term viability of ecosystems), SHP faces the challenge of rebalancing ecological and economic benefits [6].
Since 2018, relevant state departments have been vigorously promoting the cleanup and rectification of SHP, and various regions have made efforts to resolve the ecological problems of SHP by clearing out illegal power stations and implementing ecological flow regulation [7]. By the end of 2022, the number of SHP plants in China will be reduced to about 42,400, but the installed capacity will still reach 84 million kW, which shows that SHP still has an important position and potential in sustainable development [8]. From 2024 onwards, China’s SHP development has entered a new stage of “green reinvention”; on the one hand, the phase-out type of SHP exit mechanism is deepening, and SHP plant clean-up and rectification is being carried out in key regions such as the Yangtze River Economic Belt and the Yellow River Watershed [9]; on the other hand, the stock of SHP is undergoing a comprehensive green transformation to achieve a balance between power generation benefits and ecological protection. Based on the “Green and Low Carbon Transformation Industry Guidance Catalogue (2024 Edition)” [10], the relevant departments have proposed to carry out comprehensive renewal and renovation of SHP and promote SHP to move towards a new stage of ecology, safety, and high efficiency.
In recent years, the research on SHP plant cleanup and rectification in China mainly focuses on the two main cores of dynamic tracking of operational effects and multifunctional synergistic optimization. From the aspect of SHP plants cleaning and rectification tracking, the research in recent years focuses on the water-sand relationship, applies the method of numerical simulation, and points out that after dam removal, the impounded sand embankment underwent rapid incision within two months—experiencing extremely high rates of erosion (up to several million tons per day)—followed by a gradual widening of the river channel [11]; Some scholars focus on the ecological environment and study the impact of dam removal on the ecological environment from both short and long time scales by sampling experimental methods, pointing out the spatio-temporal heterogeneity and multi-scale coupling characteristics of its impact [12,13]. As for power generation, SHP can provide clean and renewable energy for remote areas [14], and the variable speed control strategy for the efficient operation of SHP plants can effectively solve the problem of energy shortage [15]. SHP contributes to the energy supply and also plays a role in flood control. Relevant research on the current SHP construction and management of some of the problems in the analysis, and on how to do a good job of SHP flood safety, put forward the corresponding countermeasures and recommendations, to a certain extent, to improve the flood control potential of SHP [16].
According to the relevant information, in the process of implementing and rectifying SHP, some places have also shown a tendency toward simplistic means of governance and one-sided decision-making assessment. For example, they do not strictly follow the “Green Small Hydropower Evaluation Criteria (SL/T 752-2020)” [17] to implement the classification and rectification, and the phenomenon of “one-size-fits-all” shutdown of compliant power stations and non-compliant projects [5]; after the dismantling of the power stations, there is a lack of systematic ecological monitoring, which leads to the lack of dynamic assessment of the natural restoration of the river, the reconstruction of watershed ecosystems, and other key aspects; and they ignore the chain reaction triggered by the shutdown of SHP plants [18]. The chain reaction triggered by the closure of SHP is neglected, and the social costs, such as the reduction in local financial and tax revenues, the gap in the supply of alternative energy sources, and the resettlement of former practitioner groups, are not sufficiently predicted. This governance bias affects the sustainability of ecological restoration, and there is an urgent need to establish a comprehensive assessment mechanism covering the ecological, economic, and social dimensions to ensure systemic balance in the green transition process.
In summary, current research focuses on summarizing and sorting out the ecological, economic, and flood control benefits of SHP, and a systematic assessment for ecological restoration of SHP after dismantling has not yet been developed. To address this gap, this review explicitly states two objectives: (1) Systematic evaluation of the impact of SHP rectification on the ecology and hydrology of the Chishui River watershed. (2) Analyze the key issues in SHP remediation and propose practical policy and monitoring recommendations. Given this, this study investigates the effectiveness of five typical SHP dismantling in the Chishui River Watershed through literature review, data collection, on-site survey, field visits, etc., and initially puts forward suggestions such as scientific assessment, government control, green industry transformation, employment guarantee, and power grid renovation to promote the transformation and upgrading of SHP and high-quality development. The five selected SHPs span different reaches and stream orders of the Chishui River and encompass all types of diversion-based power generation; therefore, the sample used in this study is considered adequate and representative.

2. Overview of the Chishui River Watershed

We selected the Chishui River as the study area because it uniquely preserves a near-natural main-stem flow and hosts nationally important rare and endemic fish habitats, making it an ideal, policy-relevant case for assessing SHP remediation and ecological restoration. Originating in Zhaotong, Yunnan Province, with a watershed area of 20,440 km2 [19]. The Chishui River is an important part of the Upper Yangtze River Rare and Endemic Fish National Nature Reserve and has an irreplaceable role in mitigating the adverse effects of the Three Gorges Project and the development of hydropower in the lower reaches of the Jinsha River on the rare and endemic fish and it has been known as “the last refuge of the rare and endemic fish in the upper reaches of the Yangtze River”. The protection and restoration of the water ecology of the Chishui River has a demonstration and leading role in maintaining fish diversity in the upper reaches of the Yangtze River, promoting regional high-quality development, and creating a new situation of ecological civilization [20].
With economic and social development, China pays more and more attention to the protection of the ecological environment and insists on integrating the construction of ecological civilization into all aspects of industrial construction [21]. At present, the economic and social development of the Chishui River Watershed is relatively lagging, the industrial structure is unreasonable, and it is overly dependent on the brewing industry. Secondly, the ecological environment in the region is under great pressure, with insufficient environmental protection facilities and prominent problems of pollution from agricultural surface sources, rural life, and the winemaking industry; at the same time, there is a shortage of water resources, with frequent problems of seasonal and regional water shortages; and the mismatch between the level of economic development in the watershed and the need for ecological protection has seriously constrained the sustainable development of the Chishui River Watershed [22].

3. Development History of SHP in the Chishui River Watershed

As of May 2020, 373 SHP plants were built in the Chishui River Watershed, with a total installed capacity of 449,400 kW [23]. All SHP plants in the Chishui River Watershed are constructed on tributaries, and the construction has gone through three stages, reflecting the logic of the evolution of China’s rural energy supply model (Figure 3).

3.1. Initial Stage (1950s–1970s)

Following the founding of the People’s Republic of China, rural electrification emerged as a national priority. Leveraging its abundant water resources, the Chishui River Watershed became one of the early pilot regions for SHP development. During the 1950s, SHP plants were constructed primarily to support rural lighting and agricultural production. While these early facilities were limited in scale and technological sophistication, they laid a critical foundation for subsequent expansion [24].

3.2. Rapid Development Stage (1980s–1990s)

During the reform and opening-up period, rural electrification efforts were significantly intensified, and the Chishui River Watershed witnessed rapid growth in SHP construction. The 1980s saw the deployment of numerous SHP plants, accompanied by improvements in technology and increases in installed capacity. By the 1990s, enhanced investment and technological upgrades further expanded generation capacity and operational efficiency, positioning SHP as a key electricity source in the region [25].

3.3. Optimization and Upgrading Stage (Early 2000s–Present)

Since the early 21st century, increasing national emphasis on clean energy and sustainability has driven a shift in SHP development in the Chishui River Watershed toward efficiency and environmental compatibility. Figure 4 shows the changes in installed capacity of SHP in China from 2013 to 2022 [1]. Upgrades in equipment and operational technologies have enhanced both power output and ecological performance [26]. Simultaneously, outdated stations have been decommissioned or consolidated, while newly built facilities place greater emphasis on ecological sustainability.

3.4. Benefits and Impacts of SHP

The construction of SHP has effectively promoted the economic development of the Chishui River Watershed, facilitated the vigorous development of industry and agriculture, and significantly improved the living conditions of residents. At the level of livelihood security, the construction of SHP has provided a stable power supply for the Chishui River Watershed and the surrounding areas, especially in remote mountainous areas and rural areas, and has strongly contributed to the improvement of rural infrastructure [27]. In terms of disaster prevention and control, the construction of SHP helps to improve the disaster prevention and mitigation capacity of the Chishui River Watershed, and in the event of extreme weather or heavy rainfall, the SHP plants regulate the water level through the reservoirs to slow down the impact of floods, which strengthens the flood prevention capacity of the watershed [28].
However, the expansion of the number and scope of SHP development also brings a series of ecological and environmental problems. There were 36, 61, and 100 fish species found in the upper, middle, and lower reaches of the Chishui River [29]. The intensive development of SHP has had a significant impact on the river’s water ecology. Some SHP plants that do not strictly implement devolved ecological flows lead to the drying up of rivers and insufficient water, which affects the reproductive activities of fish [30]. For example, frequent changes in water levels caused by power station peaking can lead to the exposure of fish eggs on water plants, which die from sun exposure [31]. At the same time, overexploited SHP cuts off the migratory pathways of migratory fish [32]. Although the mainstream of the Chishui River remains in its natural state, its tributary systems have experienced plentiful hydropower development, which might have an adverse effect on river connectivity, leading to downstream nutrient transport and ecosystem fragmentation [33].

4. Progress in Green Rectification of SHP

In order to solve the ecological and environmental problems brought about by the overexploitation of SHP, the central and local governments have attached great importance to promoting green rectification and have issued opinions on carrying out the clean-up and rectification work of SHP in the Yangtze River Economic Belt. The document “Opinions of the Ministry of Water Resources, National Development and Reform Commission, Ministry of Ecology and Environment, National Energy Administration on carrying out the clean-up and rectification work of Small Hydropower in the Yangtze River Economic Belt” [34] stipulates that: withdrawing from the illegal SHP plants involving the core or buffer zones of the nature reserves and seriously damaging the ecological environment within a limited period, comprehensively rectifying the SHP plants with incomplete examination and approval formalities and impacting on the ecological environment, and perfecting the construction and management system and the supervisory system, to effectively resolve that will also improve the construction management system and regulatory system, effectively solve the outstanding ecological problems of SHP in the Yangtze River Economic Zone and promote the scientific, orderly and sustainable development of SHP.
The local government set up a leading group for SHP plant clean-up and rectification work, formulated a clean-up and rectification program, and implemented the “one-stop one policy” rectification strategy. In September 2020, Yunnan, Guizhou, and Sichuan provinces set up a cross-provincial coordination mechanism to clean up and rectify SHP plants in the Chishui River Watershed, following the principle of “Ecological Priority: Retire as Much as Possible”, formulated a graded and classified exit plan, completely dismantled 301 SHP plants located in the core ecological zone, and partially dismantled 28 SHP plants with comprehensive functions, with an overall exit ratio of 88.2% [35].
In Chishui City, for example, there were 68 SHP plants with a total installed capacity of 93,190 kW at the historical peak before the dismantling work, and the composition of the SHP plants is shown in Figure 5, among which there were 29 micro SHP plants (with an installed capacity of ≤500 kW) [36], which accounted for 42.65% of the total number of SHP plants. There are 26 mini SHP plants (installed capacity 501–2000 kW) [37], accounting for 38.24% of the total number of SHP plants. There are 9 medium SHP plants (installed capacity of 2001–5000 kW) [38], accounting for 13.24% of the total number of SHP plants. There are 4 large SHP plants (installed capacity 5000–50,000 kW [39]), accounting for 5.88% of the total number of SHP plants.
The situation of SHP plants cleaning and withdrawal in Chishui City is shown in Table 1. Historically, to support rapid economic development, the Chishui River watershed underwent extensive hydropower development with numerous small plants constructed. As economic conditions improved, greater attention was directed to environmental protection: the high density of SHP facilities caused substantial reductions in river flow and contraction of fish habitat, and cascade installations on tributaries altered the hydrological regime of protected reaches of the mainstem [40]. Consequently, a program of clearance and remediation for SHP was initiated. Those SHP plants that perform integrated functions such as flood control, water supply, and irrigation and for which alternative measures could not be applied were rectified by constructing fish passages and retained; all other SHP plants were dismantled [41]. In the course of the comprehensive management of the watershed, government agencies solicited public input via official announcements, thereby providing an effective channel for public participation [42]. Removal operations were coordinated by the water resources department, which comprehensively considered the interests of all relevant stakeholders and organized implementation accordingly.

4.1. Decommissioned SHP Plants

In recent years, Chishui City has actively promoted the dismantling of SHP plants. Between 2020 and 2024, the city has dismantled a total of 56 SHP plants, accounting for 82.35% of the total number of SHP plants. Specifically, 12 were dismantled in 2020, 16 in 2021, 12 in 2022, 10 in 2023, and 6 in 2024. The types of dismantling are mainly micro SHP plants and mini SHP plants, which have the largest number of dismantling and the largest proportion of dismantling, reaching 93% and 85%, respectively (Figure 6).

4.1.1. Case 1—Impoundment-Type SHP Plant on a Secondary Tributary of the Xishui River

The SHP plant, with an installed capacity of 1260 kW, is classified as a small-scale facility. Construction commenced in July 2008, and it was completed and brought into operation by July 2009. It was decommissioned in June 2024 (Figure 7). The decommissioning process involves the removal of the diversion dam, penstock, and forebay sealing, and the dismantling of all electromechanical equipment. Field investigations revealed that post-demolition, a considerable volume of sediment remained in the river channel. The channel exhibited signs of narrowing, and baseflow was significantly reduced. As the dismantling took place during the flood season, rainfall mobilized the exposed sediments, transporting them downstream and resulting in observable deterioration in water quality. (SHP parameters are shown in Figure A1 in the Appendix A).

4.1.2. Case 2—Impoundment-Type SHP Plant on a First-Order Tributary

Before its decommissioning, it had been fully shut down and disconnected from the grid. The dam’s sluice gates were opened, allowing unimpeded river flow to pass through the structure (Figure 8). Upon initiation of the demolition process, the dam body was gradually dismantled. Excavated debris was promptly removed and transported to designated disposal sites. As shown in the figure, the powerhouse is located on the left bank, where ecological flow release continues. The riverbed in this section is composed of resistant substrate, and significant fluvial scouring is evident. Three to four years after decommissioning, a remnant structure or terrain feature protruding above the water surface remains approximately 12 m high. While the removal of the station did not have a noticeable effect on overall river discharge, it altered the continuity of the water surface, potentially affecting hydraulic connectivity and aquatic habitat conditions, particularly for fish species. Sediment accumulation in the vicinity was minimal. This is attributed partly to the wide upstream and narrow downstream channel morphology, which promotes efficient flow conveyance and sediment transport. Additionally, the elapsed time since decommissioning allowed accumulated sediment to be gradually flushed downstream by natural hydrologic processes.

4.1.3. Case 3—Run-of-River SHP Plant on a First-Order Tributary

It had a catchment area of 78.5 km2, a reservoir capacity of 38,000 m3, and a gravity dam with a maximum height of 10.9 m. Its normal pool level was 493.2 m, with flood control thresholds set at 495 m (flood-limited level), 497.4 m (design flood), and 497.61 m (check flood). Following removal, the exposed riverbed showed significant sediment deposition, altered flow dynamics, and pronounced channel incision—approximately 5 m along the banks and 3 m in the central channel (Figure 9). (SHP parameters are shown in Figure A2 in Appendix A).
The main reasons for prioritizing the dismantling of SHP plants found through the above research cases are as follows:
  • Ecological protection needs. Some SHP plants are located in ecologically sensitive areas such as nature reserves, ecological function protection zones, important watersheds, or water source protection zones, fish migratory corridors, and the habitats of specific species. The ecosystems in these areas are fragile, and the construction and operation of SHP plants cause damage to the water ecosystem, affecting biodiversity and the ecological balance [43]. For example, SHP plants block river connectivity and change the natural flow of rivers, affecting fish migration and reproduction; they lead to dewatering of downstream rivers, destroying the habitat of aquatic organisms and compressing the living space of fish [44].
  • Policy orientation and optimization of energy structure. On the one hand, all local governments actively respond to the national policy to remove SHP as one of the important initiatives to promote green development; for example, “The Law of the People’s Republic of China on the Protection of the Yangtze River” [45] explicitly requires the rectification of SHP projects that have a significant impact on the ecology [46]. On the other hand, in some of the SHP plants, due to the age of repair, there are large security risks. The smart grid needs to be a stable and controllable power supply [47]. For SHP plants, due to the seasonal flow of the influence of the weak regulatory capacity, it is difficult to adapt to the flexibility of the new power system needs, seriously affecting the stability of the energy structure of the power grid [48].
  • Small installed capacity, economic benefits are not obvious. Due to their limited installed capacity, mini and micro SHP plants have a power generation capacity that might be difficult to meet the demand for large-scale electricity consumption, and their economic benefits are relatively low. These SHP plants are more likely to be included in the scope of dismantling because of their relatively high operating costs, difficulty in maintenance and management, and limited contribution to local economic development [49].

4.2. SHP Plants Retained

After the rectification, there are currently 12 SHP plants still in operation in the county (accounting for 17.6% of the historical peak), located along the Xishui River, Datong River, and Fengxi River. Among them, there is one dam-type SHP plant and eleven diversion-type SHP plants, with a total installed capacity of 40,830 kW. Most SHP plants have an installed capacity below 5000 kW, including 10 SHP plants on the Xishui River accounting for 77.96% of the total installed capacity; one station on the Fengxi River accounting for 19.59%; and one SHP plant on the Datong River accounting for 2.45% [50].

4.2.1. Case 4—A Dam-Type SHP Plant Downstream on the Mainstream of the Xishui River

It has a catchment area of 944 km2 and a total reservoir capacity of 4.2 million m3. The maximum dam height is 23.4 m, with a crest elevation of 298.4 m and a crest length of 66 m. The overflow dam elevation is 290.5 m, and the arch dam height is 14.5 m. The normal storage level is 290.5 m, the design flood level is 295.88 m, and the checked flood level is 298.32 m. Its installed capacity is 3200 kW. To mitigate ecological impacts during construction, an ecological flow sluice gate was installed, with ecological discharge controlled by sediment-flushing gate openings and a verified ecological flow of 2.93 m3/s. The plant is a multifunctional facility, primarily serving power generation to supply electricity to surrounding areas. Besides power generation, the station provides additional services such as flood control, irrigation, water supply, and ecological flow release. The plant was retained during the rectification process. The cascade hub structures mainly include masonry gravity dams, diversion channels, forebays under pressure, and the downstream powerhouse. The plant is located 450 m downstream on the left bank of the dam, situated on relatively open terrain, and it is a surface-type powerhouse, housing two units each with a capacity of 1500 kW, and it guarantees an output of 619 kW (combined)/540 kW (single), with an average annual generation of 13.2 million kWh (combined)/12.5 million kWh (single) (see Figure 10). (Guanyinyan SHP. Available online: https://baike.baidu.com/item/%E6%96%BD%E7%A7%89%E5%8E%BF%E8%A7%82%E9%9F%B3%E5%B2%A9%E6%B0%B4%E7%94%B5%E7%AB%99/1096876 (accessed on 10 August 2025)).

4.2.2. Case 5—A Diversion-Type SHP Plant on the Mainstream of the Xishui River

The plant was constructed in November 2005 and commissioned in June 2008. It has a normal storage level of 324 m and adopts a diversion development scheme, with an installed capacity of 7500 kW. The long-term average annual power generation is 27.9 million kWh. The main hub structures of the plant include a weir dam, open diversion channels, diversion tunnels, a forebay under pressure, pressure steel penstocks, and the powerhouse. To protect the river ecology, the ecological water discharge of the plant is set at 0.7 m3/s. The plant is required to release the prescribed ecological flow to ensure continuous river flow during operation. When water resources are scarce, the dam effectively accumulates scarce flow from the main channel; when water is abundant, it guides the flow smoothly through the main riverbed, ensuring river continuity and flood peak formation. These operational characteristics align with natural conditions. However, the dam construction has caused certain impacts on fish migration and spawning and has hindered genetic exchange among fish populations [51] (see Figure 11). (Matan SHP. Available online: https://baike.baidu.com/item/%E9%A9%AC%E6%BB%A9%E6%B0%B4%E7%94%B5%E7%AB%99/2894308 (accessed on 11 August 2025)).
Through the research, it was found that these SHP plants were retained due to the following reasons:
  • Flood prevention. Some of the SHP plants have the function of flood prevention, effectively reducing the impact of floods on downstream areas by regulating the water level of reservoirs. In addition, these plants also have the function of regulating the flow of rivers during flood and dry periods, thus maintaining the stability of river ecosystems to a certain extent.
  • Livelihood needs. Some SHP plants not only undertake the functions of water supply, access, and electricity for local villagers but also play an important role in guaranteeing water for downstream residents’ living and agricultural irrigation. For example, the retention of the SHP plant in Case 5 ensures the basic living needs of residents and promotes social stability and development.
  • Existing ecological measures. Most of the retained SHP plants have already adopted ecological protection measures, such as ecological flow release and the construction of fish migration corridors, in order to mitigate the impact on the ecological environment. The implementation of these measures has effectively protected the river ecosystem and promoted the recovery of biodiversity.
  • Far from the mainstream of the Chishui River. Most SHP plants are located in the tributaries of the Chishui River, in areas far from the mainstream of the Chishui River. It reduces the impact of SHP plants on the ecosystem of the Chishui River’s mainstream.
  • Large installed capacity. Among the retained SHP plants, some of them have relatively large installed capacities, with high power generation efficiency and economic benefits. For example, the installed capacity of SHP plants on the Xishui River accounts for 77.96% of the total [50], and these plants have a strong power generation capacity and are able to provide a stable power supply for the local area. In addition, SHP plants with larger installed capacity have adopted more stringent measures in ecological protection, such as ecological flow release, to mitigate the negative impact on the river [52].

5. Ecological Changes Following the Removal of SHP Plants

5.1. Enhancing Biological Resource Quantity and Diversity

The removal of SHP plants in the Chishui River Watershed has significantly increased the amount and diversity of biological resources. For example, in Case 1, the removal of SHP plants removed physical barriers to fish migration, allowing the restoration of habitat corridors for migratory fish such as Yangtze sturgeon and coelacanth. Then in the Datong River in the Chishui River Watershed, the proportion of flow-loving fish increased significantly after the plant was removed, suggesting that the improvement of river connectivity has a positive effect on the recovery and diversity enhancement of fish populations [53].
According to the tracking and monitoring data, after the removal of typical SHP plants in major tributaries such as the Xishui and Datong Rivers, the number of fish species upstream and downstream of the original dam site increased by about 6.67% and 70% [35], respectively, in a short period after the removal of the SHP plant in the tributaries of the Chishui River. For example, following the removal of the Lianghui Hydropower Station on the Datong River, fish species richness increased from 11 to 13 in the reach upstream of the former dam and from 12 to 19 in the downstream reach [54].

5.2. Enhancing River Connectivity

Removal of SHP plants on the tributaries of the Chishui River and improvement of river connectivity [55,56]. By the end of 2022, a cumulative total of 270 SHP plants were removed, accounting for 72.4% of the total [35]. A certain study shows that surveys before (2010–2012) and after (2014–2016) removal along ~303 km of riverbank captured 107,335 individuals of 39 species. After removal, fish assemblages upstream of former dams became more similar to downstream assemblages (average similarity score increased by ~31%) [57]. For example, as shown in research Case 2, after the removal of the SHP plant, the release of silt and sediment from the river upstream of the original dam site will lead to siltation in the short term, and the river will be blocked. In the long term, with the inflow of water from upstream as well as the scouring of rainwater, coupled with the river channel being wide at the top and narrow at the bottom, the rapid passage of water allows sediment to be transported downstream quickly, and the connectivity of the river is significantly enhanced.

5.3. Improve Water Quality

According to Case 3, removing the SHP plant initially exposed the riverbed and caused a short-term pulse of sediment that temporarily degraded downstream water quality. However, a multi-site study of small surface-release dams shows this short-term impact is often followed by relatively rapid recovery of dissolved oxygen (DO) and other indicators after removal: before removal most impoundments (≈60%) had lower DO than upstream (on average 1.15 mg·L−1 lower), five impacted reaches experienced minimum DO below the common water-quality threshold of 5 mg·L−1, and after dam removal 4 of those 5 reaches recovered to meet the DO standard. Within one year of removal, impoundment DO had returned to upstream reference conditions at ~80% of sites, with the magnitude of recovery strongly related to the pre-removal DO deficit; sites with wider impoundments and more cultivated watershed land showed the largest pre-removal DO declines [58]. Thus, the Case 3 observations are consistent with these findings: although dismantling produced a short-term sediment/quality setback, as downstream discharge increased DO improved substantially and most formerly impaired reaches met DO standards within about a year—indicating that removal partly alleviated river dewatering and contributed to water-quality improvement.

5.4. Ensuring Ecological Flow

According to the “Guidelines for Assessing the Ecological Water Demand of Rivers and Lakes (Trial) (SL/Z 479-2010)” [59], the ecological flow of the river is in principle not less than 10–20% of the multi-year average flow. Some of the retained SHP plants, as shown in Cases 4 and 5, ensure that the river does not stop flowing by installing ecological flow discharge facilities, which reduces the compression of the living space for aquatic organisms, provides a more stable living environment for aquatic organisms, and helps to maintain the balance of the river ecosystem [60]. After removing the SHP plant with the substandard ecological flow, the natural runoff of the mainstream and tributaries of the Chishui River was gradually restored, and the exposed riverbed and insufficient water downstream of the dam site were reduced, reducing the length, scope and intensity of dry and wet fluctuations in the growing environment.

6. Issues Encountered During the Demolition of SHP Plants

6.1. Insufficient Follow-Up and Sampling Studies

Currently, the ecological impact assessment of SHP plants mainly focuses on river connectivity, biodiversity, water quality, etc. [61,62,63], but there is a lack of systematic assessment criteria and data support for the ecological restoration effect after dismantling and insufficient tracking and sampling studies for follow-up, which leads to an inability to comprehensively understand the effect of dismantling work and the existing problems. For example, changes in the water quality of the river channel after removal, the impact of sediment release on the downstream, and the recovery of biodiversity all require long-term follow-up and sampling studies [64].

6.2. Economic Pressure and Social Costs

The removal of small hydropower plants has exerted noticeable pressure on local fiscal resources and economic development. Decommissioning reduces local electricity production and the associated revenues, which can constrain public budgets and limit investment in infrastructure. The resulting gap in locally available generation often forces remote, mountainous communities to rely on more expensive and higher-carbon energy alternatives, undermining environmental and sustainability goals. Moreover, plant closures can lead to job losses among former employees and make it difficult for affected groups to secure replacement livelihoods, posing challenges to social stability and long-term economic resilience [65].

6.3. Livelihood and Infrastructure Challenges

The rural power supply is unstable. After the dismantling of SHP plants, the stability of power supply in some remote villages has declined, affecting the lives of residents and agricultural production. For example, the stability of the power supply in a village has decreased, causing inconvenience to the lives of residents and agricultural production and weakening of flood defense function. The removal of some of the plants with flood defense functions exposes downstream areas to higher flood risks during extreme weather [66].

7. Recommendations for Follow-Up Research on SHP Plants Renovation

7.1. Improve Evaluation Standards and Strengthen Long-Term Monitoring

A comprehensive evaluation system of WQI (water quality index) and TLI (comprehensive trophic state index) was constructed [67], as well as a high- and low-frequency sampling strategy at the river network level in the trunk and tributaries of the Chishui River was developed to scientifically measure the comprehensive effects of ecosystem restoration, socio-economic impacts, and substitution benefits after the dismantling or rectification of SHP. In addition, with the help of high-resolution satellite and remote sensing shadow images, we can dynamically identify the disturbed patches caused by soil erosion and water pollution to provide early warning for the environmental monitoring after the rectification of SHP plants [68].

7.2. Strengthen Financial Security and Expand Employment Opportunities

Vigorously develop relevant green industries with the characteristics of the Chishui River, and develop mountain tourism services with the help of Guizhou’s mountainous characteristics to increase local financial income. Optimize the structure of financial expenditure, improve the efficiency of the use of financial funds, and reduce unnecessary expenses. Provide re-employment opportunities and help train former SHP plant practitioners in tracking sampling and ecological environment monitoring skills to fill the human resource gap in the Chishui River sampling and monitoring sector.

7.3. Strengthen the Power Infrastructure and Improve Flood Control Capabilities

Reasonably calculate the energy gap faced by the region after dismantling, enhance the power generation capacity of the non-withdrawn SHP plants through pipeline optimization, generator modification, replacement of high-efficiency runners, etc. [69], and promote distributed energy sources, such as solar power generation and wind power generation, to improve the power supply capacity and stability of the power grid. After the withdrawal of some SHP plants, the number of SHP plants has been reduced, which has brought great pressure on the flood control of the watershed, and the flood should be accurately forecasted through refined hydrological forecasting models (e.g., SWAT, etc.), which can provide a scientific basis and a longer early warning time for the decision-making of flood control [70]. The flood control performance of SHP plants can also be improved through gate control system modification and upgrading of flood relief facilities.
In addition, the impact of SHP plant dismantling involves many fields, such as ecology, flood control, people’s livelihoods, energy, economic, and social development, etc., which requires comprehensive tracking research. We have strengthened cooperation with scientific research institutions such as the Yangtze River Commission and comprehensive water conservancy colleges and universities and carried out systematic tracking observation and sampling studies with the help of interdisciplinary advantages. Establish an integrated “air-sky-ground” monitoring network platform, combining the Gaofen series of remote sensing satellites, unmanned aerial vehicles, and artificial sampling on the ground with precise analysis in the laboratory, and make real-time data on water quality (PH, dissolved oxygen, conductivity, etc.), ecology (aquatic biodiversity, benthic organisms, etc.), and hydrology (flow velocity, flow rate, etc.) obtained from the tracking observations and sampling studies public promptly to provide a scientific basis for government decision-making and social supervision. Flow velocity, flow rate, etc. data in a timely and open manner, providing a scientific basis for government decision-making and social supervision [71].
In summary, the removal of SHP plants in the Chishui River Watershed is an ecological restoration initiative to reverse overexploitation and should be regarded as a major opportunity to promote the construction of ecological civilization in the Yangtze River Watershed. The removal of SHP plants at the same time should be from a more macroscopic perspective of integrated planning. Grasp this opportunity to promote the construction of ecological civilization in the Chishui River watershed and effectively achieve the harmonious coexistence of man and nature. On the one hand, it is necessary to improve the ecological compensation mechanism [72] through the establishment of multi-body participation in the ecological compensation fund and a reasonable definition of the sharing of rights and responsibilities; on the other hand, it should be actively introduced into the market-oriented means, the use of green finance, carbon trading, payment for ecological services, and other tools to effectively make up for the economic and social losses brought about by the withdrawal of SHP [73]. Moreover, to mitigate the adverse impacts on water quality, it is essential not only to rely on engineering and technical measures but also to incorporate ecological restoration strategies, such as the restoration of aquatic vegetation [74], the construction of fish migration passages [75], and the regulation of reservoir ecological flows [76]. Finally, it is suggested that the priority order for dismantling SHP plants should be determined through expert discussions and field investigations, with particular emphasis on the magnitude of their impact on river connectivity and the operating years of the SHP plants [77].

8. Conclusions

This paper addresses the ecological and environmental problems brought about by the development of SHP in the Chishui River Watershed, taking Chishui City in the Chishui River Watershed as the research object, and explores the way to balance the ecological and economic benefits of SHP through in-depth analysis of the development history, impacts, and withdrawals of SHP. The study found that although SHP has made an important contribution to promoting rural electrification and economic development, overexploitation has also led to ecological problems such as river outflow and biodiversity decay. To solve these problems, the local government has actively implemented SHP plant cleanup and rectification work, and the removal of SHP has hurt the ecological environment in a short period and on a localized basis in the river watershed, but the removal of SHP has effectively improved the ecological environment in the long term and on a watershed-wide scale.
However, the process of SHP withdrawal has also revealed challenges such as increased economic pressure, alternative energy gap, job loss, and unstable rural power supply. Given this, this paper puts forward recommendations for establishing scientific assessment criteria, strengthening government control, developing green industries, increasing the development and utilization of clean energy, providing job training and re-employment opportunities, and enhancing rural power grid transformation. These recommendations aim to balance ecological benefits and economic development and provide lessons for the green transformation of SHP. This study focuses primarily on SHP and lacks a systematic comparison of the long-term impacts of large hydropower plants or dam removals. Future work will further investigate the significant differences between large and small plants in spatial scale, impoundment geometry, and the duration of ecological impacts.

Author Contributions

Conceptualization, W.G. and Z.W.; methodology, W.G. and K.W.; validation, K.W. and X.L.; formal analysis, W.G. and K.W.; resources, Q.J.; writing—original draft preparation, W.G.; writing—review and editing, Z.W., X.W. and X.L.; visualization, W.G.; supervision, Z.W. and X.W.; project administration, Z.W.; funding acquisition, Z.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Key Research and Development Program of China (2024YFF1307804); and the National Natural Science Foundation of China, Youth Program (41101191).

Data Availability Statement

No new data were created or analyzed in this study. Data sharing is not applicable to this article.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
SHPsmall hydropower

Appendix A

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Figure A1. Case 1 SHP parameters.
Figure A1. Case 1 SHP parameters.
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Figure A2. Case3 SHP parameters.
Figure A2. Case3 SHP parameters.
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Figure 1. Number of countries included in the global SHP database by region.
Figure 1. Number of countries included in the global SHP database by region.
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Figure 2. Number of existing and potential SHP plants in the global SHP database by region.
Figure 2. Number of existing and potential SHP plants in the global SHP database by region.
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Figure 3. Spatial distribution of SHP plants in the Chishui River Watershed.
Figure 3. Spatial distribution of SHP plants in the Chishui River Watershed.
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Figure 4. Changes in installed capacity of SHP in China (2013–2022).
Figure 4. Changes in installed capacity of SHP in China (2013–2022).
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Figure 5. Composition of the SHP plants in Chishui City in the Chishui River Watershed.
Figure 5. Composition of the SHP plants in Chishui City in the Chishui River Watershed.
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Figure 6. Dismantling of SHP plants.
Figure 6. Dismantling of SHP plants.
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Figure 7. Comparison between before and after dismantling of a post-dam SHP plant on a second-tier tributary of the Xishui River.
Figure 7. Comparison between before and after dismantling of a post-dam SHP plant on a second-tier tributary of the Xishui River.
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Figure 8. Comparison between before and after dismantling of a post-dam SHP plant on a first-level tributary of the Chishui River.
Figure 8. Comparison between before and after dismantling of a post-dam SHP plant on a first-level tributary of the Chishui River.
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Figure 9. Current status of dismantling of a run-of-river SHP plant on a primary tributary of the Chishui River.
Figure 9. Current status of dismantling of a run-of-river SHP plant on a primary tributary of the Chishui River.
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Figure 10. A post-dam SHP plant on the mainstream of the Xishui River.
Figure 10. A post-dam SHP plant on the mainstream of the Xishui River.
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Figure 11. A diversion-type SHP plant on the mainstream of the Xishui River.
Figure 11. A diversion-type SHP plant on the mainstream of the Xishui River.
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Table 1. SHP plant demolition in Chishui City, Guizhou Province, China.
Table 1. SHP plant demolition in Chishui City, Guizhou Province, China.
Number of SHPYear of DemolitionInstalled Capacity (kW)PositionNumber of SHPYear of DemolitionInstalled Capacity (kW)Position
12020100Guixiang Village, Datong Town352022320Miliang Village, Yuanhou Town
22020160Huaping Village, Datong Town3620224000Heping Village, Guandu Town
32020200Liangjiang Village, Fuxing Town372022400Jianshan Village, Hushi Town
42020200Renyou Village, Fuxing Town382022800Aihua Village, Bing’an Town
52020320Kaixuan Village, Fuxing Town392022500Cangqi Town, Cangqi Village
62020200Jinsha Village, Hushi Town402022640Yuanhou Town Bizhao Village
72020860Gaodong Village, Changsha Town4120231000Huaping Village, Datong Town
82020160Hongguan Village, Changsha Town4220231030Lianfeng Village, Baoyuan Town
92020200Yaling Village, Wanglong Town432023500Pingtan Village, Baiyun Town
102020100Yanjia Village, Wenhua Town442023640Pingtan Village, Baiyun Town
112020225Yufeng Village, Baoyuan Town452023640Changqi Town Wuqi Village
122020520Sanfo Village, Bing’an Town462023640Fengxi Village, Fuxing Town
1320213200Sanfo Village, Bing’an Town4720231000Cangqi Town, Cangqi Village
142021200Sanfo Village, Bing’an Town482023500Lianhua Village, Baoyuan Town
1520212500Sanfo Village, Bing’an Town4920231000Kangqiao Village, Changqi Town
1620213200Changxing Village, Changsha Town5020236400Renyou Village, Fuxing Town
172021200Datong Village, Datong Town5120241260Xianhe Village, Guandu Town
18202175Datong Village, Datong Town522024630Lianhua Village, Baoyuan Town
192021320Huaping Village, Datong Town532024800Lianhua Village, Baoyuan Town
202021320Huaping Village, Datong Town5420242520Shilin Village, Yuanhou Town
212021320Renyou Village, Fuxing Town5520243200Hushi Village, Hushi Town
222021445Xingzhu Village, Lianghekou Town5620241000Huaping Village, Datong Town
232021320Shichang Village, Changsha Town57retained200Gaozhu Village, Hushi Town
242021200Hushi Village, Hushi Town58retained200Gaozhu Village, Hushi Town
2520211890Xianhe Village, Guandu Town59retained1000Lianhua Village, Baoyuan Town
26202155Lianfeng Village, Baoyuan Township60retained950Yuwan Village, Guandu Town
2720211600Changxing Village, Changsha Town61retained8000Kaixuan Village, Fuxing Town
282021750Panlong Village, Lianghekou Township62retained1600Hongxing Village, Shibao Town
292022445Darong Village, Lianghekou Town63retained1880Xingnong Village, Shibao Town
302022375Daba Village, Lianghekou Town64retained3200Yuwan Village, Guandu Town
3120221000Minzu Village, Datong Town65retained7500Datan Village, Shibao Town
322022640Lianghuishui Village, Datong Town66retained2500Yiqun Village, Shibao Town
332022840Xingzhu Village, Lianghekou Town67retained9000Yiqun Village, Shibao Town
342022800Xingzhu Village, Lianghekou Town68retained4800Yiqun Village, Shibao Town
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Gao, W.; Wang, Z.; Wang, K.; Wang, X.; Li, X.; Jiang, Q. Effectiveness of Small Hydropower Plants Dismantling in the Chishui River Watershed and Recommendations for Follow-Up Studies. Water 2025, 17, 2909. https://doi.org/10.3390/w17192909

AMA Style

Gao W, Wang Z, Wang K, Wang X, Li X, Jiang Q. Effectiveness of Small Hydropower Plants Dismantling in the Chishui River Watershed and Recommendations for Follow-Up Studies. Water. 2025; 17(19):2909. https://doi.org/10.3390/w17192909

Chicago/Turabian Style

Gao, Wenzhuo, Zhigang Wang, Ke Wang, Xianxun Wang, Xiao Li, and Qunli Jiang. 2025. "Effectiveness of Small Hydropower Plants Dismantling in the Chishui River Watershed and Recommendations for Follow-Up Studies" Water 17, no. 19: 2909. https://doi.org/10.3390/w17192909

APA Style

Gao, W., Wang, Z., Wang, K., Wang, X., Li, X., & Jiang, Q. (2025). Effectiveness of Small Hydropower Plants Dismantling in the Chishui River Watershed and Recommendations for Follow-Up Studies. Water, 17(19), 2909. https://doi.org/10.3390/w17192909

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