Jinjiang River Research Articles

Lithium Pollution and Its Associated Health Risks in the Largest Lithium Extraction Industrial Area in China.

Lithium (Li) is an important resource that drives sustainable mobility and renewable energy. Its demand is projected to continue to increase in the coming decades. However, the risk of Li pollution has also emerged as a global concern. Here, we investigated the pollution characteristics, sources, exposure levels, and associated health risks of Li in the Jinjiang River basin, the largest area for Li2CO3 production in China. Our results revealed the dominant role of Li extraction activities in the pollution of the river, with over 95% of dissolved Li in downstream river water being emitted from this source. Moreover, the Li concentration in aquatic plants (i.e., water hyacinth) and animals (i.e., fish) significantly increased from upstream to downstream areas, indicating a significant risk to local aquatic ecosystems. More importantly, our study found that local residents were suffering potential chronic noncarcinogenic health risks primarily from consuming contaminated water and vegetables. We also investigated the pollution characteristics of associated elements present in Li ores (e.g., Rb, Cs, Ni, and F-). By uncovering the remarkable impact of Li extraction activities on the Li content in ecosystems for the first time, our study emphasizes the importance of evaluating Li pollution from Li-related industrial activities, including mining, extraction, and recovery.

Spatial Distribution Patterns of Phytoplankton and Their Relationship with Environmental Factors in the Jinjiang River, China

Our study aims to investigate the water quality and distribution patterns of phytoplankton communities in the Jinjiang River Basin in Quanzhou, as well as their relationship with environmental factors. We integrated data from the national water quality databases of the two main tributaries of the West and East Jinjiang Rivers between 2020 and 2023, supplemented by field surveys. Redundancy analysis was used to explore the effect of environmental factors on phytoplankton communities. Our findings revealed that the West Jinjiang River experienced a significant influence from excessive fertilizer use in tea cultivation, leading to an increase in TN concentrations compared to the East Jinjiang River. The abundance of phytoplankton in the Jinjiang River Basin was 105 cells·L−1, with phytoplankton being dominated by Chlorophyta, Cyanphyta, and diatoms, accounting for an average of 50%, 20%, and 19% of the total phytoplankton abundance, respectively. Redundancy analysis indicated that temperature, pH, and nutrient concentrations were important factors influencing the phytoplankton communities. With increasing temperature and nutrients concentrations, the abundance of Chlorophyta and Dinophyta significantly increased. This study provides a solid foundation for the regular “health diagnosis” of crucial rivers and lakes in Quanzhou and supports the establishment of a health guarantee system for rivers and lakes.

Spatial distribution, mass flux, and ecological risk of antibiotics in Taiwan and Luzon Straits: A case in the West Pacific Region

Emerging pollutants are hazardous to the ecological environment and human health, and these issues have attracted increasing attention from scholars. In the current study, the Taiwan Strait is long and narrow, highly influenced by terrestrial domains, and frequently disturbed by human activities. Conversely, the Luzon Strait is an open sea far from the shore, and the impact of human activities on it is minimal. The description of antibiotics in two different types of seas revealed that contaminants were most commonly detected in both straits. In particular, the coasts of the Minjiang River, Jinjiang River, and Jiulong River were found to be pollution hotspots in the Taiwan Strait. The calculation of risk quotients revealed that antibiotics were more sensitive to algae. Furthermore, estimation of the risk quotients of the mixtures found that antibiotics in the environment do not pose a high risk to aquatic organisms at different trophic levels.

Spatial and temporal distribution and ecological risk assessment of typical antibiotics in natural and wastewater of Jinjiang River Basin.

Antibiotics are widely used in human medical, livestock, and aquaculture fields. Most antibiotics are water-soluble and cannot be fully absorbed by humans or animals. If feces or wastewater containing antibiotics are improperly treated or discharged directly into surface water or groundwater, it will undoubtedly have an impact on aquatic organisms. The Ganjiang River is the largest river in Jiangxi Province and the largest tributary of Poyang Lake Basin. Jinjiang River, a tributary of Ganjiang River, is a typical livestock and poultry breeding area in the Poyang Lake Basin, along which many townships and counties are distributed. Gao'an and Shanggao counties are important agricultural and animal husbandry production areas in Jiangxi Province. In this paper, automatic solid phase extraction-ultra high performance liquid chromatography-mass spectrometry (SPE-UPLC-MS/MS) technology was used to simultaneously detect 27 antibiotics in 5 categories of macrolides, tetracyclines, quinolones, nitroimidazoles and sulfonamides in water. Based on this method, the concentrations and distributions of these antibiotics were analyzed. Ecological risk assessment of the Jinjiang River Basin was conducted using the ecological risk quotient method, aiming to supplement antibiotic data in the Jinjiang River Basin and provide scientific basis for local ecological environment management. The research results indicate that from 2019 to 2021, two years later, there was an increase in the use of Sulfadiazine and Roxithromycin in the Jinjiang River Basin, while the usage of Ciprofloxacin and Oxytetracycline was relatively low. In 2021, out of the 27 antibiotics, 24 were detected in surface water, 20 in groundwater, and all in wastewater. Among them, Sulfamethoxazole was the most widely used antibiotic, primarily in livestock and poultry farming. Gao'an City, a key breeding area in the Jinjiang River Basin, exhibited the highest concentration of Sulfamethoxazole at 409.96 ng·L-1, which far exceeds other antibiotics and warrants significant attention. A comparison of surface water concentrations between the Jinjiang River and 12 other regions revealed higher overall pollution levels of Roxithromycin and Sulfamethoxazole. Furthermore, according to the ecological risk assessment results, only Sulfamethoxazole poses a moderate risk to aquatic organisms.

Development of composite drought indices for the coastal areas of southeastern China: A case study of Jinjiang and Jiulongjiang River basins

Given the complexity of coastal drought events and their unique impacts on coastal ecosystems, it is vital to develop drought indices that can reflect both freshwater availability and impacts on ecological resources to better assess drought conditions over coastal regions. Existing drought indices developed for upland areas may not be suitable to capture the timing and severity of drought in the coastal regions. To explore coastal drought issue more comprehensively, this paper constructed the Coastal Composite Drought Indices (CCDIs) based on the entropy-weighted Euclidean distance method by freely combining six variables: precipitation (P), evaporation (E), runoff (R), salinity (S), Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST), in the Jinjiang River Basin (JJRB) and the Jiulong River Basin (JLRB). The CCDIs were later compared to the Standardized Precipitation Index (SPI) and Palmer Drought Severity Index (PDSI) to select the Optimized Drought Indices (ODIs). The results demonstrated that the Precipitation Evaporation Runoff Composite Index (PER) is more sensitive to capturing short-term coastal drought events compared to other CCDIs. PER performed better than SPI and PDSI in detecting the onset of drought development and reflecting drought persistence. The salinity exhibited mixed responses to long-term drought events in different river basins depending on the size of each coastal system and its characteristics, thus raising the issue of regional applicability. Through a series of cross-comparisons and validations, the Runoff NDVI LST Composite Index (RNL) and the Runoff Salinity NDVI Composite Index (RSN) were chosen to monitor long-term droughts in the JJRB and JLRB, respectively. Overall, all three indices have the ability to capture the dynamics and trends of the variables and provide better information on the occurrence, persistence, and end of droughts in coastal areas.

Faults and stratigraphic boundaries control evolution of the huge debris flows along the Jinjiang River, China

This paper investigates the controlling factors of the evolution of debris flows along the Jinjiang River, which is located in an active orogen. The debris flows along the Jinjiang River are threatening nomads and pastures, as well as the power station on the river and its workers. Remote sensing images, geological maps, and field investigations were conducted to determine the distribution of the lithologies, faults, and debris flows. A total of 82.2 km of riverbank and 108 debris flows, including 22 huge flows, were investigated. The results indicate that the distribution of the huge debris flows is primarily controlled by either faults or boundaries between the sedimentary rocks and basalt. Both the faults and the stratigraphic boundaries play crucial roles in the evolution of the huge debris flows along the river. The fractured zone of faults and stratigraphic boundaries provides loose resource materials for the debris flows and is a weak strip prone to incision to become a debris flow valley. However, the lithology has relatively less impact on the evolution of the huge debris flows.

Enhanced phosphorus electrosorption using Fe, N-co-doped porous electrode via capacitive deionization

ABSTRACT Excessive phosphorus discharge causes water eutrophication and disturbs the homeostasis of aquatic ecosystems. Capacitive deionization (CDI) has been proven to be a more energy-efficient and environmentally friendly technology for removing phosphorus. Raw carbon (Raw C) electrodes are widely used in CDI. However, the phosphorus removal capacity of most unmodified Raw C still needs to be enhanced. Therefore, the Fe, N-co-doped carbon prepared in this study was expected to further improve the phosphorus removal performance. Herein, the optimal electrode with 5% Fe (FeNC) had an approximately 2.7 times higher adsorption capacity than Raw C. At a low concentration (5 mg P/L), FeNC exhibited a high maximum removal capacity of 4.28 mg P/g. Under reversed voltage, the phosphorus was easily desorbed by deionized water. Ion competition studies showed that coexisting ions adversely affected phosphorus adsorption onto FeNC in the order SO4 2- > NO3 - > Cl-. Furthermore, the energy consumption of FeNC was calculated to be as low as 0.0069 kWh/g P and 0.023 kWh/m3 water under 1.2 V. More importantly, phosphorus removal by FeNC during CDI was demonstrated in simulated natural water from the Jinjiang River (Chengdu, China). This study indicated that FeNC is expected to be a potential electrode for CDI dephosphorization.

Evolution of sedimentary dynamic process/pattern in the Quanzhou Bay under impact of Typhoon Matmo (2014)

Typhoons are one of the most dramatic weather events affecting the nearshore environment, which significantly affect the processes of sediment erosion, transport, and redeposition in a short period of time. In this study, the hydrodynamic evolution and sedimentary source and sink processes in the Quanzhou Bay after the typhoon’s passing were systematically studied by using the water column observation data (flow field and turbidity) and the surface sediment grain-size analysis results obtained in two surveys: 3–4 days and 1 month after Typhoon Matmo (2014), respectively. The results show that the typhoon process significantly increased the sediment flux input from the Jinjiang River and expanded the sediment “sink” in the Jinjiang River estuary. After the typhoon’s passing, the sediments in the bay were redistributed under the stable tidal transport, and the estuarine sediments were transformed from a sink of riverine material into a source of sediment transport and diffusion. Typhoon processes play an important role in the evolution of estuarine sediments and sedimentary environment.

Investigation on the influence of spur dikes on the weighted usable area for the two native species in a city-crossing river

Spur dikes, mainly for regulating water flow and protecting river banks in the past, were found recently to have the ability to increase the fish physical habitat and improve aquatic system. However, the effect of spur dikes on aquatic system was generally ignored previously, and the studies on the influence of spur dikes on improving specific native fish physical habitat are still rare. This study reports a numerical investigation for the effects of spur dikes on the physical habitat and the minimum ecological flow in the Jinjiang River. Three spur dikes are placed along the inner bend in the study reach and two fish species of the Pelteobagrus fulvidraco and carps are selected as the target species. Two-dimensional water depth and velocity field are simulated in different discharges and the results are used to predict the corresponding weight use area (WUA). The differences of WUA before and after the building of spur dikes for the two selected fish species show that spur dikes have a significant effect on the physical habitats. And the minimum ecological flows from the instream flow increment approach are different for the two objective fish species and are also considerably impacted by spur dikes.

Effects of suspended particles in the Jinjiang River Estuary on the physiological and biochemical characteristics of Microcystis flos-aquae.

The effects of different concentrations (100, 150, 200, 250mg/L) and different particle sizes (0-75μm, 75-120μm, 120-150μm, 150-500μm) on the soluble protein content, superoxide dismutase (SOD) and catalase (CAT) activity, malondialdehyde (MDA) content, chlorophyll a (Chla) content, and photosynthetic parameters of Microcystis flos-aquae were studied, and the mechanism of the effect of suspended particulate matter on the physiology and biochemistry of Microcystis flos-aquae was discussed. The results showed that the soluble protein content of Microcystis flos-aquae did not change noticeably after being stressed by suspended particles of different concentrations/diameters. The SOD activity of Microcystis flos-aquae first increased and then decreased with increasing suspended particulate matter concentrations. The SOD activity of Microcystis flos-aquae reached 28.03 U/mL when the concentration of suspended particulate matter was 100mg/L. The CAT activity of Microcystis flos-aquae increased with increasing concentrations of suspended particles and reached a maximum value of 12.45 U/mg prot in the 250mg/L concentration group, showing a certain dose effect. Small particles had a more significant effect on SOD, CAT, and MDA in Microcystis flos-aquae than large particles. The larger the concentration was and the smaller the particle size was, the stronger the attenuation of light and the lower the content of Chla. Both the maximum quantum yield of PSII (Fv/Fm) and the potential photosynthetic activity of PSII (Fv/F0) of Microcystis flos-aquae increased at first and then decreased under different concentrations/sizes of suspended particles. The relative electron transfer rate gradually returned to a normal level over time. There was no significant difference in the initial slope (α) value between the treatment group and the control group, and the maximum photo synthetic rate (ETRmax) and the semilight saturation (Ik) decreased.

Occurrence, distribution and environmental risk of 19 anthelmintic drugs in river water and sediment from the Jinjiang River, China.

This study explored the occurrence and distribution of 19 anthelmintic drugs (ADs) including the benzimidazole group, salicylanilide group, imidazothiazole group, tetrahydropyrimidine group, diphenylsulfide group, macrocyclic lactone group and hexahydropyrazine group in river water and sediment of the Jinjiang River in Sichuan, China, during summer and winter seasons. All targets were detected in river water (up to 74.64 ng L-1) and sediment (up to 1701 ng g-1) samples. The predominant ADs were benzimidazoles regardless of seasons and matrices, accounting for 43-82% of the total anthelmintic abundance. Obvious seasonal variation of AD concentrations in the two matrices was observed, which could be attributed to the seasonality of human and veterinary uses of ADs. Evident spatial variation (urban and rural areas) of ADs in winter was indicative of the influence of anthropogenic activities on the environmental concentration of ADs. Though benzimidazoles accumulated in the water and sediment with the highest concentration among all the ADs, macrocyclic lactones were of the highest risk to non-target organisms through ecological risk assessment, with an RQEcotox value up to 2713. This work contributes to comprehensively assessing the contamination level, ecological level and transmission characteristics of ADs in the environment.

Wild birds-the sentinel of antibiotic resistance for urban river: Study on egrets and Jinjiang river in Chengdu, China

Antibiotic resistance has become a comprehensive and complicated environmental problem. It is of great importance to effectively determine the abundance of various antibiotic resistance genes (ARGs) in the environment. Here, we attempted to find a practical method for monitoring environmental antibiotic resistance. The results of culture-based analysis of antibiotic resistance and metagenomic sequencing indicate that egrets inhabiting along the urban river (Jinjiang River) can be used as the sentinel of environmental antibiotic resistance. The antibiotic resistance in the environment fluctuated with time, while that in the wild bird was relatively stable. The network analysis based on metagenomic sequencing data gave the co-occurrence pattern of ARGs. The overall situation of the antibiotic resistance in the river was determined by quantifying several module hub genes of the co-occurrence network in river sediments. The temporal and spatial distribution of ARGs in Jinjiang River is highly correlated with that of human gut-specific bacteriophage (crAssphage), which indicates that one main source of the antibiotic resistance in the river is likely to be municipal sewage. The mobility potential of ARGs varying among different niches suggests the transmission direction of antibiotic resistance in the environment.

Characteristics and sources of microplastic pollution in the water and sediments of the Jinjiang River Basin, Fujian Province, China

Microplastic pollution is widely distributed from surface water to sediments to groundwater vertically and from land to the ocean horizontally. This study collected samples from surface water, groundwater, and sediments from upper to lower reaches and then to the estuary in 16 typical areas in the Jinjiang River Basin, Fujian Province, China. Afterward, it determined the components and abundance of the microplastics and analyzed the possible microplastic sources through principal component analysis (PCA). As a result, seven main components of microplastics were detected, i.e., polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyformaldehyde (POM), nylon 6 (PA6), and polystyrene (PS). Among them, PE and PP were found to have the highest proportion in the surface water and sediments and in the groundwater, respectively. The surface water, groundwater, and sediments had average microplastic abundance of 1.6 n/L, 2.7 n/L and 33.8 n/kg, respectively. The microplastics in the sediments had the largest particle size, while those in the groundwater had the smallest particle size. Compared with water bodies and sediments in other areas, those in the study area generally have medium-low-level microplastic abundance. Three pollution sources were determined according to PCA, i.e., the dominant agriculture-forestry-fishery source, domestic wastewater, and industrial production. This study can provide a scientific basis for the control of microplastics in rivers.©2022 China Geology Editorial Office.

First Report of Cercospora rodmanii Causing Leaf and Petiole Lesions on Water Hyacinth in China.

The rapid spread and colonization of water hyacinth (Eichhornia crassipes) leads to a series of serious environmental problems for water bodies, prompting microbiologists to develop effective mycoherbicides to alleviate the water hyacinth population (Julien et al. 2001). In September 2020, numerous leaftip diebacks and petiole rots of water hyacinth, with 40 to 50% incidence, were observed within an area of 2 ha (ca. 2 km) mat on Jinjiang River tributary, Fujian, China. Ten infected leaf samples were collected and symptomatic tissues were cut into small pieces, surface disinfected in 75% ethanol followed by 0.1% MgCl2 solution and placed on potato dextrose agar (PDA). Pure cultures (Isolates J1 and J5) were obtained and their colonies on PDA appeared as white villi with wrinkled surfaces and dense colorless mycelium on the upper surface, while they were dark olivaceous-gray at the bottom. Internal mycelium consisted of septate, branched, smooth hyphae. There lacked stromata. Conidiophores were solitary to 2 to 5 in loose fascicles, thick-walled, conically truncated, 40 to 80 × 5 to 8 µm. Conidiogenous cells integrated, terminal, 30 to 150 × 4 to 6 µm, slightly protuberant, apical and lateral. Conidia were solitary, hyaline, acicular to obclavate, slightly curved, acute at the apex, 50 to 80 ×3 to 6 µm, indistinctly 1 to 3 septate. Genomic DNA from the two isolates was extracted for PCR, and the internal transcribed spacers (ITS), calmodulin (CAL), translation elongation factor 1-alpha (TEF), actin (ACT), histone H3 (H3) and chitin synthase (CHS) were amplified and sequenced using the primer pairs ITS1/ITS4, CL1/CL2A, EF1Fd/EF1Rd, ACT1Fd/ACT1Rd, CYLH3F/CYLH3R and CHS-79F/CHS-345R (Weir et al. 2012; White et al. 1990), respectively. The ITS (MZ436974-MZ436975), CAL (MZ519385-MZ519386), TEF (OK340826-OK340827), ACT (OK340824-OK340825), H3 (OK340828-OK340829) and CHS (MZ519387-MZ519388) sequences were deposited in GenBank. A phylogenetic tree based on concatenated sequences of ITS-CAL-TEF-ACT-H3-CHS from the genus Cercospora was constructed using a maximum likelihood method, showing that the present isolates and Cercospora rodmanii formed a monophyletic group with 99% bootstrap support. Therefore, the fungus was identified as C. rodmanii (Groenewald et al. 2013; Nguanhom et al. 2015). To test Koch's postulates, petioles of a set of 20 water hyacinth seedlings of 30 to 40 days old were wounded using a sterile needle and then spray-inoculated with 20 μl of the spore suspension of each isolate at 106 CFU/ml. Another set of 20 seedlings inoculated with sterile distilled water served as the controls. Inoculated plants were kept in 50-liter plastic tanks and maintained in a greenhouse at room temperature 22 to 28°C with a relative humidity of 80 to 85%. After 7 to 20 days, lesions were observed on the inoculated leaves but not on the control leaves. The same fungus was reisolated and identified by microscopy and PCR-sequencing. The pathogenicity test was conducted twice. Cercospora rodmanii and C. piaropi have been reported on water hyacinth in America, Brazil, México, and Zambia (Charudattan et al. 1985; Montenegro-Calderón, 2011; Moran, 2015). To our knowledge, this is the first report of C. rodmanii causing leaf and petiole lesions on water hyacinth in China. This report will help identify indigenous plant pathogens in China and develop a novel bioherbicide strategy for control of water hyacinth.

Antibiotic Pollution Characteristics and Ecological Risk Assessment in Jinjiang River Basin, Jiangxi Province

The concentration and distribution characteristics of 27 antibiotics, including 8 sulfonamides, 9 quinolones, 4 tetracyclines, 4 macrolides, and 2 nitroimidazoles, in the surface water, groundwater, and wastewater of the Jinjiang River basin in Jiangxi province were determined using solid-phase extraction combined with ultra-performance liquid chromatography-tandem triple quadrupole mass spectrometry. The results showed that there was antibiotic pollution in the waters of the Jinjiang River basin. A total of 20 antibiotics were detected in the surface water, with a concentration range of 32.3-280 ng·L-1. There were 15 types of antibiotics detected in the groundwater, and the concentration range was 28.4-55.8 ng·L-1. Twenty-one types of antibiotics were detected in the wastewater, with a concentration range of 231-8.71×104 ng·L-1. A comparison with the concentrations of eight common antibiotics in rivers and lakes in China and abroad showed that the pollution level in the Jinjiang River basin was at a medium level. By comparing the concentrations of sulfamethoxazole in groundwater from domestic and international samples, the groundwater pollution in the Jinjiang River basin was clearly in the middle and lower range. A comparison of the concentrations of the three antibiotics in the aquaculture wastewater from domestic and abroad samples indicated that the pollution level of sulfadiazine in the aquaculture wastewater from the Jinjiang River basin was relatively high. The ecological risk assessment results showed that there were nine medium- and high-risk antibiotics, which were clarithromycin, erythromycin, ciprofloxacin, sulfathiazole, roxithromycin, tetracycline, ofloxacin, enrofloxacin, and sulfamethoxazole; the rest were low-risk or no-risk antibiotics.

A Hybrid Model for Water Quality Prediction Based on an Artificial Neural Network, Wavelet Transform, and Long Short-Term Memory

Clean water is an indispensable essential resource on which humans and other living beings depend. Therefore, the establishment of a water quality prediction model to predict future water quality conditions has a significant social and economic value. In this study, a model based on an artificial neural network (ANN), discrete wavelet transform (DWT), and long short-term memory (LSTM) was constructed to predict the water quality of the Jinjiang River. Firstly, a multi-layer perceptron neural network was used to process the missing values based on the time series in the water quality dataset used in this research. Secondly, the Daubechies 5 (Db5) wavelet was used to divide the water quality data into low-frequency signals and high-frequency signals. Then, the signals were used as the input of LSTM, and LSTM was used for training, testing, and prediction. Finally, the prediction results were compared with the nonlinear auto regression (NAR) neural network model, the ANN-LSTM model, the ARIMA model, multi-layer perceptron neural networks, the LSTM model, and the CNN-LSTM model. The outcome indicated that the ANN-WT-LSTM model proposed in this study performed better than previous models in many evaluation indices. Therefore, the research methods of this study can provide technical support and practical reference for water quality monitoring and the management of the Jinjiang River and other basins.

Identifying spatial mismatches between the supply and demand of recreation services for sustainable urban river management: a case study of Jinjiang River in Chengdu, China

Urban river recreation services (URRS) are very important for improving the quality of urban life. Understanding the balance between the supply and demand of URRS can facilitate sustainable urban river management. First, we analyzed the spatial patterns of the URRS supply and demand in Jinjiang River. We then identified spatial mismatches from three dimensions (river recreation spaces, residential communities, and the service region) by using the Gaussian two-step floating catchment area (2SFCA) method. Finally, we revealed the main influencing factors and their interactions. The results showed that: (1) the URRS supply gradually increased from upstream to downstream; (2) the URRS demand in the midstream was the strongest, followed by the downstream and upstream; (3) the supply-demand mismatches were severe, with 50.29% of the URRS region in short supply; and (4) the main influencing factors included distance to the city center, supply of river recreation spaces, and riverfront distance. Road density, residential community density, and distance to the city center could enhance the impact of other factors. Our research can improve the quantity and distribution of urban riverfront green spaces, as well as provide a reference for urban residential layout or planning.

Wild Birds-The Sentinel of Antibiotic Resistance for Urban River: Study on Egrets and Jinjiang River in Chengdu, China

Wild Birds-The Sentinel of Antibiotic Resistance for Urban River: Study on Egrets and Jinjiang River in Chengdu, China

Wild Birds-The Sentinel of Antibiotic Resistance for Urban River: Study on Egrets and Jinjiang River in Chengdu, China

Wild Birds-The Sentinel of Antibiotic Resistance for Urban River: Study on Egrets and Jinjiang River in Chengdu, China

SWAT model-based quantification of the impact of land-use change on forest-regulated water flow

For most watersheds, land-use change leads to changes in forest-regulated water flow, not only in relation to changes in forest area, but also in relation to conversion of forest and other land-use types. To reveal the impacts of land-use change on forest-regulated water flow, this study proposes computational formulas for multi-time scale analysis of the regulated water flow in a watershed with various land-use types, whose spatial distribution is discontinuous in the hydrological response unit (HRU) scale using the Soil and Water Assessment Tool (SWAT). The impacts of land-use change on forest-regulated water flow were then computed with the formulas and a transfer matrix between the forest and other land-use types. The Jinjiang River Watershed which covers an area of approximately 5042 km2 in the southeast coast of China, was selected as the study area and the results showed that (1) The annual forest-regulated water flow in the Jinjiang River Basin was 271.41–565.25 mm. The monthly flow ranged from −29.15 mm to 154.59 mm, which was positive for most months of the year. The forest-regulated water flow was positive in extreme precipitation period, and negative in extremely dry period. Forest-regulated water flow significantly varied with various time scales. (2) During 1985–2006, The forest area in the Jinjiang River basin decreased from 3094.84 km2 to 2805.81 km2, which led to a reduction of 44.99–83.51 mm in annual, 0.54–6.36 mm in monthly, and 0.73–5.30 mm in daily forest-regulated water flow, respectively and (3) the proposed method is suitable for multi-time scale analysis of regulated water flow of various land-use types whose spatial distribution is discontinuous in a watershed. It provides a newer approach for evaluating the impacts of land-use changes on water flow regulation function in watersheds with respect to separate land-use types and their spatial conversions.