西部人居环境学刊2025，Vol.40Issue(5)：38-44,7.DOI:10.13791/j.cnki.hsfwest.20250913001
山地深水湖库水生态健康诊断与风险防控研究
Water ecological health assessment and risk management of mountainous deep-water reservoirs:A case study of Tengzigou Reservoir in southwest China
摘要
Abstract
Mountainous deep-water reservoirs,formed by damming river channels and impounding water in valley depressions,represent a distinctive landscape type in southwest China.These reservoirs provide essential ecosystem services—including flood control,hydropower generation,water supply,and recreational opportunities—and are increasingly recognized as critical nodes for regional ecological security and human well-being.A representative case is the Tengzigou Reservoir in Chongqing's Shizhu County,designated as a National Wetland Park in 2019 due to its ecological and scenic value.Since 2014,this reservoir has experienced recurrent seasonal cyanobacterial blooms,raising concerns about aquatic ecological health and the suitability of the local living environment.To address these challenges,this study conducted comprehensive in situ monitoring from April 2022 to March 2023 across eight sampling sites within the reservoir and its two main tributaries(Shazi River and Yuelai River).The investigation integrated physical,chemical,and biological indicators—including water quality parameters(e.g.,total phosphorus,dissolved oxygen,pH,total nitrogen),phytoplankton community structure,fish assemblages,and benthic macroinvertebrates—to holistically assess the reservoir's ecological status.Results indicated that the overall water quality of Tengzigou Reservoir was classified as Grade III according to China's Surface Water Environmental Quality Standards(GB 3838-2002).However,significant spatiotemporal heterogeneity was observed.Total phosphorus exhibited the highest exceedance rate at 47.78％,with concentrations ranging from 0.003 to 0.35 mg/L(mean:0.05 mg/L).Dissolved oxygen fell below the Class III threshold in 26.54％of samples,with some deep-layer measurements dropping below 1 mg/L,indicating localized hypoxia.pH exceeded the upper limit of 9 in 24.69％of samples,with a mean value of 8.17.Total nitrogen exceeded the Class III standard in 16.96％of samples(range:0.11-2.05 mg/L;mean:0.65 mg/L),while ammonia nitrogen and chemical oxygen demand rarely surpassed thresholds.The reservoir is in a mesotrophic to lightly eutrophic state.Chlorophyll-a concentrations ranged from 1.4 to 17.5 μg/L(mean:6.6 μg/L),with 9.36％of values exceeding 10 μg/L—indicative of elevated algal biomass.A total of 13 algal species were identified,primarily comprising green algae,cyanobacteria,diatoms,cryptophytes,and dinoflagellates.Cyanobacteria dominated during summer months(June to October),peaking in July when they accounted for 70.38％of the phytoplankton community.Blue-green algal density reached a maximum of 1.79×107 cells/L in July 2022 at the Yuelai River inflow zone(S5 to S7),constituting a mild surface bloom.Densities were significantly lower in spring and winter,with cyanobacteria undetectable from December to March.Biological surveys recorded 24 fish species,including 20 Cypriniformes,1 Perciformes,and 3 Siluriformes.Dominant species included crucian carp,common carp,silver carp,and topmouth gudgeon.Six species were endemic to China,and one invasive species(mirror carp)was detected.Most fish(21 of 24)were adapted to lentic or slow-flowing habitats,reflecting the reservoir's altered hydrology.Trophic composition included 11 omnivorous,10 carnivorous,and 3 herbivorous species,suggesting a moderately complex food web without strong dominance by filter-feeders.A total of 23 benthic taxa were identified,predominantly aquatic insects(22 taxa),especially Diptera(Chironomidae)and Ephemeroptera,along with one annelid species.Chironomid larvae dominated in the reservoir core(S4)from August to October,while site-specific shifts occurred in tributaries—such as Trichoptera in Yuelai River in August,and different Ephemeroptera genera in September and October.The prevalence of pollution-tolerant Chironomidae indicates potential eutrophication stress.Vertical profiling revealed strong thermal stratification in the deep reservoir basin(S3)during summer.A distinct thermocline formed between 2-5 m depth in July,with a temperature gradient exceeding 10℃between epilimnion and hypolimnion.In contrast,inflow rivers(e.g.,S1)remained fully mixed throughout the monitoring period.Nutrient analysis showed that total phosphorus concentrations averaged 0.04 mg/L in July—exceeding the 0.02 mg/L bloom warning threshold—but declined sharply to 0.006 mg/L by September during prolonged dry conditions with minimal rainfall.This rapid decrease,coinciding with the cessation of surface runoff,underscores the dominant contribution of agricultural non-point sources to phosphorus loading,as further confirmed by source apportionment indicating that 85％of total phosphorus originated from agricultural activities.These results indicate that the Tengzigou Reservoir watershed maintains a generally favorable aquatic ecological condition,yet faces latent risks.While biological indicators suggest the absence of severe eutrophication,recurrent seasonal cyanobacterial blooms remain a concern.These blooms are closely linked to high water temperatures,elevated phosphorus levels—primarily from agricultural non-point sources—and summer thermal stratification.To address these challenges,it recommends establishing a bloom monitoring and early-warning system tailored to mountainous deep-water reservoirs.Ecological reservoir operations should be optimized to weaken thermal stratification,while algal suppression measures can be deployed in high-risk zones.Crucially,watershed-scale control of agricultural runoff—through buffer strips,improved fertilizer management,and best practices—is essential to reduce phosphorus loading.Integrating ecological functions with aesthetic landscape design along shorelines can further enhance both water quality and livability.Sustained implementation of this integrated approach will support long-term ecological resilience and regional sustainability.关键词
水生态健康/生态系统服务/山地湖库/富营养化/流域管理Key words
water ecological health/ecosystem services/mountainous reservoir/eutrophication/watershed management分类
资源环境引用本文复制引用
李伟,李锗镡,赵丽,杨巍,肖邦,汤杨阳,赵亮..山地深水湖库水生态健康诊断与风险防控研究[J].西部人居环境学刊,2025,40(5):38-44,7.基金项目
重庆市生态环境局科研项目(2022-118) （2022-118）
国家自然科学基金项目(31700401、U20A20326) （31700401、U20A20326）
