Guanting Reservoir Research Articles

Perceived ecosystem services differ substantially from calculated services using biophysical models

ContextEcosystem services are fundamental for the well-being of residents and are an important basis for making regional sustainable development decisions. Existing studies mainly capture ecosystem services perceived by residents through questionnaires, or quantify the provision of regional ecosystem services through economic evaluation and biophysical evaluation. However, the discrepancy between model calculations and residents' perceptions remains lacking.ObjectivesRapidly urbanizing watersheds can serve as a prime example for exploring the differences in ecosystem service outcomes between the two perspectives.MethodsIn this study, we quantified the potential supply of nine ecosystem services and residents' perceptions of these services in the Guanting Reservoir basin through biophysical modelling and questionnaire surveys. We then analyzed the discrepancies between the two perspectives through the Wilcoxon signed-rank test.ResultsThe results showed that among the vast majority of the population, half of the nine ecosystem services exhibited significant differences in comparisons between perceived values and model-calculated ones. The differences were more prominent for regulating and supporting services among urban residents, while for provisioning and cultural services among rural residents.Conclusions These differences highlight the necessity to consider quantitative results from diverse perspectives as well as on the benefits of different groups of interest. In rapidly urbanizing watersheds, infrastructure should be reinforced in rural areas to enhance rural residents’ accessibility of ecosystem services. With regard to urban areas, particular attention should be directed towards changes in regulating and supporting services.

Coordination of interests between upstream and downstream governments in water source areas

Exploration of establishing a robust intergovernmental benefit compensation mechanism for water source areas holds significant importance in promoting regional coordinated development. Taking the Guanting Reservoir basin, a water source area in Beijing, China, as an example, we established an ecological location model with urban water sources as the core by drawing on the concept of spatial circle structure in traditional location theory. Based on this, we proposed the theory of ecological cost of water source land level difference and analyzed the basic composition of ecological cost of water source land. Finally, the differential ecological costs method was used to estimate the ideal horizontal eco-compensation funds between the downstream city of the water source (Beijing) and the upstream city (Zhangjiakou). The results are as follows: (1) the closer to the water source reservoir area and the higher the protection zone level, the greater the contribution of the ecological product value realization and the ecological protection costs to the protection of water resources in the reservoir area. (2) The compensation funds for water source areas are jointly composed of the increment of ecological product value and protection costs. (3) In 2021, the value addition of ecological products in the upstream region was 3.075 billion yuan, and the protection cost was 6.702 billion yuan. After multiplying by the differential adjustment coefficient, the horizontal eco-compensation amount that the upstream cities should receive in 2021 is 4.194 billion yuan. This study theoretically addresses the shortcomings of traditional ecological compensation, which overlooked differences in resource and environmental costs due to variations in ecological functional location. It provides a new perspective for further exploring the role of location theory in addressing inter-governmental interest coordination issues in cross-border water source areas.

Residents’ perceptions of ecosystem services in an urbanizing basin: A case study in the Guanting Reservoir basin, China

Understanding stakeholders’ differences in perceptions of ecosystem services (ES) is crucial for guiding ecological conservation and planning. However, the variations of ES perception amongst different types of residents in urbanizing areas along an urban-rural gradient are still poorly understood. Combining a questionnaire-based survey, redundancy analysis, and statistical tests, we delineated the urban-rural gradient according to local residents’ socio-economic characteristics, and investigated the differences in local residents’ perceptions of ES and potential factors affecting them in the Guanting Reservoir basin, a rapidly urbanizing basin in China. The results showed that residents living in urban-rural transitional areas attached great importance to provisioning services of providing food and domestic water, regulating services of carbon sequestration and air purification, and cultural services of providing education and training, which were 0.7%–13.1%, 0.7%–9.1% and 2.5%–21.2% higher than that of residents in other areas, respectively. Age and occupation were major factors affecting residents’ perceptions. In terms of land-use types that deliver ES, the difference in perceptions of ES delivered by grassland was the greatest amongst residents. Our results support recommendations for policymakers to take into account the stakeholders’ diverse perceptions, thus promoting residents’ sense of gain on ES.

Application of One-Dimensional Hydrodynamic Coupling Model in Complex River Channels: Taking the Yongding River as an Example

River conditions are complex and affected by human activities. Various hydraulic structures change the longitudinal slope and cross-sectional shape of the riverbed, which has a significant impact on the simulation of water-head evolution. With continuous population growth, the hydrological characteristics of the Yongding River Basin have undergone significant changes. Too little or too much water discharge may be insufficient to meet downstream ecological needs or lead to the wastage of water resources, respectively. It is necessary to consider whether the total flow in each key section can achieve the expected value under different discharge flows. Therefore, a reliable computer model is needed to simulate the evolution of the water head and changes in the water level and flow under different flow rates to achieve efficient water resource allocation. A one-dimensional hydrodynamic coupling model based on the Saint-Venant equations was established for the Yongding River Basin. Different coupling methods were employed to calibrate the coupling model parameters, using centralised water replenishment data for the autumn of 2022, and the simulation results were verified using centralised water replenishment data for the spring of 2023. The maximum error of the water-head arrival time between different river sections was 4 h, and the maximum error of the water-head arrival time from the Guanting Reservoir to each key cross-section was 6 h. The maximum flow error was less than 5 m3/s, and the changing trend of the flow over time was consistent with the measured data. The model effectively solved the problem of low accuracy of the water level and flow calculation results when using the traditional one-dimensional hydrodynamic model to simulate the flow movement of complex river channels in the Yongding River. The output results of the model include the time when the water head arrives at the key section, the change process of the water level and flow of each section, the change process of the water storage of lakes and gravel pits, and the change process of the total flow and water surface area of the key section. This paper reports data that support the development of an ecological water compensation scheme for the Yongding River.

2013–2020年海河流域农田水热碳通量及气象要素观测数据集

The present study area was located in the cropland ecosystem near Guanting Reservoir in Haihe River Basin. We conducted long-term observations of the multi-scale fluxes and meteorological elements, using various observation systems, including lysimeter, eddy covariance, large aperture scintillometer and automatic weather station/gradient of meteorological elements. This dataset consists of multi-scale fluxes (meter, hundred-meter, and kilometer-meter) and meteorological elements data. Observation items include ecosystem net carbon exchange, latent heat flux/evapotranspiration, sensible heat flux, air temperature, relative humidity, wind speed, wind direction, downward/upward shortwave radiation, downward/upward longwave radiation, net radiation, atmospheric pressure, precipitation, infrared radiation temperature, photosynthetic effective radiation, soil temperature, soil moisture, soil heat flux, and average soil temperature, etc. This dataset is processed carefully and can be used to study the effects of reservoir expansion and shrinkage on the circulation of carbon and water or other substances in the surrounding ecosystem. Additionally, it can serve as a powerful data basis for the research on relevant remote sensing estimation and model simulation.

Seasonal variations in ecosystem service supply and demand based on the SWAT model: A case study in the Guanting Reservoir Basin, China

The match and mismatch between the supply and demand of ecosystem services (ESs) are closely related to watershed sustainable development. Previous studies have mainly focused on annual or interdecadal matching relationships, and little is known about the seasonal variations of the ES supply–demand relationship. Based on the SWAT (Soil and Water Assessment Tool) model and statistical data, we took the Guanting Reservoir Basin, a transitional ecosystem from semi-arid areas to arid areas, as the study area to analyze the supply and demand of water provisioning services and soil conservation services and identified their matching relationship on the seasonal scale. The results showed that the water provisioning services was in short supply, with a supply–demand ratio of 0.81, whereas the supply of soil conservation services was in excess of demand. In terms of seasonal variation, the mismatch of water provisioning services was particularly severe in winter, followed by that in spring. The mismatch of soil conservation services was relatively severe in winter, followed by that in summer. Such mismatches imply that we must pay attention to the misallocation of resources caused by seasonal variations. It is crucial that policy-makers consider the role of reservoirs and water transfer in providing seasonal water sources for sustaining water resources in transitional areas, and optimize land management to prevent the aggravation of soil erosion in winter.

Influence of Grain on Green Patterns and Their Underlying Surface Characteristics on Water Conservation: A Case Study in a Semiarid Area

Water-conservation enhancement is a crucial objective of regional ecological restoration projects in arid and semiarid areas, and it is significantly influenced by land use/cover change (LUCC). The Grain for Green Project (GFGP) is a common strategy for ecological restoration. However, insufficient attention has been paid to the impact of reforestation patterns and the underlying surface characteristics on the effectiveness of GFGP in enhancing water conservation. In this study, a Soil and Water Assessment Tool (SWAT) scenario-based simulation was conducted to assess changes in water-conservation depth (WCD) in the Zhangjiakou section of the Guanting Reservoir basin. Redundancy analysis (RDA) and a mixed linear model were employed to determine the effects of different reforestation patterns and their underlying slope gradient and soil-type characteristics on WCD variation. The results showed that there were differences in the effect characteristics of reforestation patterns and different vegetation types on WCD changes; the effectiveness of increased water conservation is associated with the adaptation of reforestation plants to underlying characteristics. Returning farmland to evergreen forests was the most effective approach, leading to a relative increase in WCD that was 2.6 times greater than the relative increase in total WCD. WCD decreased with the slope gradient, with WCD decreasing by 0.2 mm for every 1° increase in slope. Converting grassland to evergreen forests on slopes greater than 16.19° and converting deciduous forests to grassland on slopes less than 16.19° would further increase WCD, promoting the synergistic development of ecosystem services. This study provides insights into the development of more efficient reforestation strategies to enhance water conservation in a complex terrain area.

Contamination profile and risk assessment of per- and polyfluoroalkyl substances in Guanting Reservoir, a former drinking water source with degraded water quality

The water quality of Guanting Reservoir couldn't meet the requirement of the standard for drinking water sources in China from 1997 since its pollution. The present work studied the pollution characteristics of per- and polyfluoroalkyl substances (PFASs) in water and sediments in Guanting Reservoir, 4 tributaries and WWTPs by high-performance liquid chromatography-negative electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS). The sources and risks of the identified PFASs were analyzed. There were 11 PFASs detected in the Guanting Reservoir, the average PFASs concentration was 267.89 ng/L in water and 2.17 ng/g in sediment, respectively, which are higher than those in other water sources within and outside China. Perfluorooctanoic acid (PFOA) was the main pollutant in both water and sediments, and it has potential ecological risk (0.1 < RQ < 1) in both water and sediment samples as well as potential health risk with HR value ranges in 0.25–0.64 in water in Guanting Reservoir. Sanggan River and Yongding River are the main input sources of PFASs pollution, and the direct emission from industrial production and the degradation of precursors have been shown to make a great contribution to the PFASs in Guanting Reservoir. The results suggest that continuous monitoring and integrated risk assessment in Guanting Reservoir catchment and more attention should be paid on the pollution control from Sangan River and Yongding River.

Sources of nitrogen in reservoirs of the Haihe basin (China) 2012–2017

Nitrogen (N) is essential for agricultural production. However, too much N can pollute waters. The Chinese government published several policies to reduce N losses from agricultural production to waters since 2015, which may influence river export of N to reservoirs and lakes and their pollution sources. This study aimed to quantify the trends of river export of N to five reservoirs in the Haihe basin and analyze the main sources of this N pollution from 2012 to 2017. This was done by upscaling the MARINA-Lakes (Model to Assess River Inputs of Nutrients to lAkes) model to the Haihe basin, including 22 sub-basins. From 2012 to 2017, river export of total dissolved nitrogen (TDN) to the Haihe reservoirs decreased by 11–51%, associated with a decreased contribution of point sources and an increased contribution of diffuse sources for the whole study area Sub-basins draining into Reservoir Pan-Da contributed over one-third to the total TDN export by rivers in 2012 and 2017. The share of diffuse sources in river export of TDN to the Guanting reservoir reached 63% in 2017. Among the TDN diffuse sources, the contribution of animal manure (a diffuse source) to river export of diffuse TDN increased to 28%, 25%, and 23% for the sub-basins of Reservoir Miyun, Pan-da, and Guanting from 2012 to 2017, respectively. Among the TDN point sources, direct manure discharges were the main contributors to the river export of point TDN to the Haihe reservoirs in 2012. By 2017, direct discharges of untreated human waste became another important point source, especially for the Lake Baiyangdian and Reservoir Gang-Huang. This study concludes the need for specific agricultural N management options for different reservoirs of the Haihe basin.

Improvement in water pollution control alters nutrient stoichiometry of Guanting Reservoir near Beijing, North China.

Significant improvement in wastewater treatment is the most effective way for eutrophication control, especially in semiarid regions. However, its effect on the nutrient status and stoichiometry of the receiving water body has remained poorly considered and understood at broad temporal scales. Taking Guanting Reservoir (GR) in Hebei-Beijing (P. R. China) as an example, we present a study that links a continuous monitoring dataset for GR with corresponding estimates of human-induced nutrient discharges in its watershed from the year 2006 to 2019. We find that current GR belongs to strict P limitation and the faster decrease of TP than TN concentrations and continuous increase of TN/TP mass ratios in GR are attributed to the water restoration investment-induced declining of nutrient loadings. The improved municipal wastewater treatment capacity is mainly responsible for these significant changes, due to the higher removal efficiency of TP than TN in municipal wastewater. Given the potential ecological impact on aquatic biodiversity as well as ecosystem function of changes in TN/TP ratios and higher retention rate of TP (97.4%) compared with TN (93.1%) in GR, our findings highlight that future strategy for water pollution control should not only concentrate on more nutrient reduction efficiencies but attach importance to their stoichiometric balance to reduce the potential risk of phytoplankton blooms and toxin production during the water quality recovery of lakes or reservoirs.

Difficulties and Solutions in Boundary Survey and Pile Fixing of Guanting Reservoir

Difficulties and Solutions in Boundary Survey and Pile Fixing of Guanting Reservoir

Identifying trends and driving factors of spatio-temporal water quality variation in Guanting Reservoir Basin, North China.

Assessment of river quality has been attracting a great deal of attention because of its important implications for the living environment of human beings and aquatic organisms. This study investigated the spatial and temporal variation of water quality and its possible driving factors of Guanting Reservoir Basin. For this purpose, water quality was assessed with the Canadian Council of Ministers of the Environment Water Quality Index, together with nutrient inputs and social-economic data which were collected and analyzed during the period 2009-2019. The results showed that the overall water quality in Guanting Reservoir increased over time and was rated as "good" during the studied decade. Spatially, water quality in tributary upstream of Yanghe River and Sanggan River was better than that in Guishui River, resulting in better quality in West Reservoir than in East Reservoir. Among water quality indices, total nitrogen was the main pollutant affecting the water quality of the studied area. In addition, principal component analysis and correlation analysis were applied to evaluate the relationships between the socio-economic factors and water quality variation. Urbanization and industry structure were significantly correlated with the water quality variation in upstream tributaries. The findings provide insightful understanding into the spatio-temporal variations of water quality and the associated driving factors of Guanting Reservoir basin, which would help managers in executing theoretical reference for water quality protection.

Effects of Afforestation Projects on Tradeoffs between Ecosystem Services: A Case Study of the Guanting Reservoir Basin, China

Evaluating the responses of ecosystem services (ESs) to local land-use changes is critical for understanding the effects of ecological projects related to land planning. Change patterns in the interrelationships between ESs delivered by land-use changes, which are helpful for formulating future strategies, have not been well studied. In this study, we quantified four ESs, namely water yield (WY), water and soil conservation, nonpoint pollution control, and carbon sequestration services, based on the soil and water assessment tool model (SWAT) in the Zhangjiakou section of the Guanting Reservoir watershed, a region with a high concentration of afforestation projects. The impacts of land-use changes on changes in ESs and interrelationships of ESs were investigated by redundancy analysis. The results showed that, along with afforestation, regional water conservation and soil organic carbon content increased by 3.22% and 1.08%, respectively, whereas sediment output, WY, phosphorus output, and nitrogen output decreased by 1.82%, 3.07%, 8.08%, and 12.51%, respectively. Significant tradeoffs of regional ESs were observed between WY and other ESs, while synergies existed between other ESs. Increased areas of evergreen and deciduous forests helped in conserving water, fixing carbon, and regulating runoff. Evergreen forests tended to conserve more water than deciduous forests. With the increase in grassland area, most of the ESs can be improved while introducing fewer tradeoffs compared with those of most of other land-use types. This study provided a better understanding of the effects of afforestation on ESs tradeoffs and benefits to develop better ecological conservation strategies in afforestation regions.

Analysis of reservoir environment evolution from 2000 to 2020: A case study in the Guanting Reservoir, China

Changes in different areas of the reservoir itself constitute the overall performance of the reservoir. This study obtains hydrological information based on continuous satellite images, and then makes zoning analysis of the reservoir to determine the best condition of good and stable operation of the reservoir. Based on a series of Landsat images, taking the Guanting Reservoir in Beijing, China as an example, this study quantitatively analyzed the distribution and changes in the laws of water volume and water surface temperature of the Guanting Reservoir from 2000 to 2020. Additionally, based on stability, the natural zoning of the reservoir area is carried out. The water surface range was obtained using the water index method. The water surface temperature was obtained by the radiative transfer equation method, which was analyzed in combination with the Reservoir Area Dynamic Degree (RADD) and Reservoir Shoreline Development Index (RSDI). In the last 21 years, the trend of water surface temperature of the Guanting Reservoir during different seasons has reversed. The year 2013 was a turning point, prior to which, the Guanting Reservoir experienced an obvious decline period (area reduction rate of 68.38%), followed by a rapid recovery period (area expansion rate reached 200.68%). When the reservoir water volume is relatively stable and RSDI is large, it is the best operation condition. According to the analysis of RSDI and average water surface temperature for many years, the stability of the reservoir is obtained for zoning. The unstable area of the reservoir or the general stable area, the water surface coverage and the water surface temperature change greatly, which is the area where the environment is most easily changed. The distribution of aquatic plants is consistent with the relatively unstable area of the reservoir. This study provides a valuable method for the rational management of reservoir submerged area. It also provides a basis for the rational planning of the reservoir area.

Occurrence and distribution characteristics of heavy metals in the surface water of Yongding River Basin, China.

Yongding River is a vital socioeconomic zone in China in providing daily usage for humans, animals, and running of industries and agriculture. This study first provides a comparative assessment for the heavy metal pollution in the surface water from 82 estuarine locations along the basin, including the Guanting Reservoir and seven wastewater treatment plants (WWTPs). The occurrence, distribution, potential sources, and water quality relating to the detected heavy metals were addressed. Eleven typical elements (Pb, Cr, As, Cd, Sb, Ba, V, Ti, Zn, Ni, and Be) were investigated, and the results showed that all the measured concentrations were below the WHO guideline limits. Most heavy metals exhibited higher levels in the middle of Yongding River basin due to the discharge of WWTPs. Pb, Ti, Zn, and Cd in the surface water mainly originated from anthropogenic discharge, while Sb and V were mostly contributed to geogenic sources according to the principal component analysis. Three documented methods, water quality index (WQI), heavy metal pollution (HPI), and Nemerow pollution index (Pn) values, were used to evaluate the contamination monitoring of surface water. All the locations were classified as low and moderate risk except Y12, B2, and Y13 for their Pn values were higher than 1.0. The present study highlights the status of heavy metals in Yongding River basin which is helpful in providing fundamental data for assessment of water quality and the effective protection for Yongding River basin in the future.

Acoustic investigation of fishery resources in Guanting Reservoir

This project uses acoustic methods to conduct a comprehensive survey of the fishery resources of the Guanting Reservoir. It uses the “Zigzag” survey route based on the actual situation of the reservoir, and uses the scientific fish finder (EK80, Simrad, Norway) as the main survey equipment. Post-processing software (Echoview, Myrix, Australia) analyzes the amount and distribution of biological resources. Statistical analysis of the existing reservoir resources and the spatial distribution of resource density showed that the fishery resources in the central part of the reservoir area are relatively high, the fishery resources in the waters near the dam in the southern reservoir area are second, and the northernmost fishery resources in the northern reservoir area. Resource Fengdu is relatively small. According to the analysis results of acoustic data, combined with the situation of biological sampling, various types of resources are also obtained. This survey provides basic data for the management of reservoir fishery resources and the formulation of enhancement and release plans, and provides a scientific basis for protecting the ecological resources and environment of the Guanting Reservoir.

Reconstructing Terrestrial Water Storage Anomalies Using Satellite Data to Evaluate Water Resource Shortages from 1980 to 2016 in the Inland Yongding River Basin, China

Water resources in the Yongding River basin (YRB) are one of the important fundamental conditions in supporting regional water conservation and ecological development. However, the historical changes in water resources under recent human activities remain unknown due to very limited observation data. In this study, terrestrial water storage anomalies (TWSA) as well as multiple precipitation and actual evapotranspiration products from satellites were collected, and the accuracy of the data was verified by observed data or pairwise comparisons. The TWSA during 1980-2016 was reconstructed by using the water balance method, and the reconstructed TWSA was verified using GRACE-observed TWSA, the average depth to groundwater in the Beijing Plain from historical document records and the observed runoff from Guanting Reservoir. The reconstructed TWSA data indicated that the significant decrease occurred during 2000–2016 and the average rate of decreasing trend was -11 mm/year, which may have been caused by a decrease in groundwater storage due to agricultural development. However, the reconstructed TWSA decreased slightly during 1980-1999. The establishment of the water storage deficit index (WSDI) showed that there was no drought or mild drought during 1980-1999; however, the water resource shortage during 2000-2016 was more serious due to groundwater storage decreases caused by agricultural development. The WSDI was verified by using the commonly used self-calibrated Palmer drought severity index. The findings are valuable for sustainable water resource management in the YRB.

Trend and attribution analysis of water and sediment variations in sandy rivers

AbstractHuman activities and climate change have led to significant changes in the flow and sediment of sandy rivers in northern China. The key work to reveal the changes of river water and sediment conditions is to quantitatively study the changes of precipitation, water and soil conservation in river basins, and the effect of reservoirs on sediment containment. Taking the Yongding River as a case study, we analyze the changing trend of the water and sediment into the Yongding River and find that their amount has greatly decreased. In particular, the sediment yield has decreased by more than 90% and its trend has changed, and the turning point occurred in the 1980s. Based on the statistical data analysis model, the influences of human activities on the sediment inflow of the Guanting Reservoir were quantitatively evaluated. The results show that sand retention of the upper cascade reservoirs is the main reason for the sharp reduction in sediment loads, but the sand retention effect of reservoirs has a certain time limit. Water and soil conservation played a vital role in the sediment loads reduction during the present stage. The present studies may provide insights into understanding the integrated reclamation of the river basin.

Retrieval and Evaluation of Chlorophyll-a Concentration in Reservoirs with Main Water Supply Function in Beijing, China, Based on Landsat Satellite Images.

Remote sensing retrieval is an important technology for studying water eutrophication. In this study, Guanting Reservoir with the main water supply function of Beijing was selected as the research object. Based on the measured data in 2016, 2017, and 2019, and Landsat-8 remote sensing images, the concentration and distribution of chlorophyll-a in the Guanting Reservoir were inversed. We analyzed the changes in chlorophyll-a concentration of the reservoir in Beijing and the reasons and effects. Although the concentration of chlorophyll-a in the Guanting Reservoir decreased gradually, it may still increase. The amount and stability of water storage, chlorophyll-a concentration of the supply water, and nitrogen and phosphorus concentration change are important factors affecting the chlorophyll-a concentration of the reservoir. We also found a strong correlation between the pixel values of adjacent reservoirs in the same image, so the chlorophyll-a estimation model can be applied to each other.

Tracking historical chlorophyll-a change in the guanting reservoir, Northern China, based on landsat series inter-sensor normalization

ABSTRACT The Guanting Reservoir supplied drinking water to Beijing until 1997, following which the water quality of the reservoir deteriorated. The chlorophyll-a concentration (C chl-a ) of water is an important indicator of eutrophication. Therefore, changes in the C chl-a of the Guanting Reservoir should be monitored and analysed. For more than 30 years, the monitoring of C chl-a in inland waterbodies has only been possible using the Landsat 5 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper (ETM), and Landsat 8 Operational Land Imager (OLI). However, there are data consistency problems in monitoring C chl-a using these sensors. To address this issue, this study utilized inter-sensor normalization models of the different sensors and a unified C chl-a estimation model for Landsat series data with a long time span. After inter-sensor normalization, the mean relative error (MRE) of remote sensing reflectance (R rs) between OLI and TM/ETM+ was corrected to 1–5%. The unified model of C chl-a estimation employed the normalized ratio index of blue R B and near-infrared R NIR remote sensing reflectance: (R NIR – R B): (R NIR + R B). The MRE for estimating C chl-a was 25.7% and the root-mean-square error (RMSE) was 5.65 mg m–3. The C chl-a of the Guanting Reservoir was then estimated for years between 1985 and 2019. During this time, C chl-a had a distinct seasonal distribution trend; the annual changes go through four stages, and each period shows different change characteristics. This study is the first to systematically understand the history of chlorophyll-a changes in the Guanting Reservoir over the past 30 years and provides references data for its eutrophication process and management.