Flow Water Quality Research Articles

A web GIS based integrated water resources assessment tool for Javeh Reservoir

The creation of tools and services for tracking, estimating, and predicting water resource indices that might provide authorities access to information in close to real-time is essentially a must. The considerable development of Web-Geographic Information System Decision Support System (Web-GIS DSS) allows for the analysis of geospatial data and scenarios via the internet without a traditional desktop GIS. The web GIS technology is coupled to techniques which determine water resources Carlson, and Organization for Economic Corporation and Development (OECD) Trophic Status Indices (TSIs), the water resource vulnerability index (WRVI), and social water stress index (SWSI). The water quality indices were determined by helping machine learning (ML) techniques, Decision Tree, Random Forest, and XGBoost. The performances of aforementioned MLs were compared, and the best efficient one, XGBoost, was included in the Web-GIS DSS tool. The developed Web-GIS DSS was examined in Javeh Reservoir, Kurdestan, Iran.The developed Web-GIS DSS allows the users to define the relevant features of the Javeh Reservoir system in pre-defined time horizons such as meteorological, hydrological, inflow water quality, reservoir operation strategies, downstream water demands, geographical external water transfers, etc. The results indicate that the Javeh Reservoir experiences eutrophication status according to the Carlson and OECD indices over time horizons. The water quantity assessment reveals the Javeh Reservoir's susceptibility based on WRVI, although no stress is indicated by SWSI. This susceptibility may be attributed to limited precipitation and water inflow during the simulation period, suggesting a need for comprehensive water resources management.The conclusion drawn from this research underscores the essential role of the developed Web-GIS DSS in decision-making processes for water and environment management, substantiating its practicality with accurate and user-friendly water and environmental data analysis. The tool exemplifies the potential of integrating ML and Web-GIS technologies to promote sustainable environmental practices, thereby establishing a model for future research and policy-making initiatives.

Assessment of a new nutrient management strategy to control harmful cyanobacterial blooms in Lake Taihu using a hydrodynamic-ecological model

The external nutrient loading significantly affects large shallow lakes, particularly those with intricate rive networks. In Lake Taihu, pollutant discharge standards have traditionally been quantified based on water environmental capacity, while neglecting the response characteristics of algal growth in different regions to boundary inputs. For that analysis, this study first estimated the river pollutant loadings of 16 most significant inflow and outflow rivers of Lake Taihu from 2008 to 2020 and explored the correlations between inflow water quality parameters and lacustrine chlorophyll-a levels. Results highlighted the significant influence of high river input of permanganate values in spring on the chlorophyll-a levels in the lake. Based on this, this study proposed the hypothesis that reducing the inflow concentration of permanganate in spring would inhibit algal growth, which was further validated using coupled hydrodynamic and ecological models. The simulation results indicated that the reduction of permanganate inflow concentration during spring would significantly decrease chlorophyll-a concentration in spring and summer, especially leading to a notable impact on peak values. However, due to variations in background concentrations among rivers, the extent of reduction in lake chlorophyll-a levels showed significant spatial differences. Additionally, analysis of extracted algal bloom areas revealed that there still remained a relatively high risk of algal blooms occurring in the main regions, particularly during autumn when inflow pollutant concentrations increased rapidly. These findings emphasized the importance of formulating reasonable exogenous reduction schemes, which should consider the concentration and variation trend of inflow pollutants, as well as the response characteristics of algal bloom growth in different lake zones to the boundary.

Controls on the composition of dissolved organic matter in treatment wetland source waters of South Florida, USA

Dissolved organic matter (DOM) plays an important role in the phosphorus (P) and nitrogen (N) cycle, but the examination of coupled biogeochemical cycling in treatment wetlands, like the Everglades Stormwater Treatment Areas (STAs), has been limited. Here, we studied eight STA inflow waters to gain insights into the production and potential photo- and biolability of DOM in surface waters flowing into these treatment wetlands. A suite of optical and fluorometric indices was coupled with amino acid and bulk elemental analyses to evaluate differences in inflow water quality for particulate organic matter (POM), DOM (<0.2 μm), and high and low molecular weight DOM (HMW-DOM and LMW-DOM). A photochemical experiment was conducted with these inflow waters to assess how solar exposure alters DOM turnover and its relationship with nutrient concentrations, and to evaluate the influence of photochemistry on potential STA performance. The DOM of STA inflow water was predominantly composed of allochthonous terrestrial sources, and the LMW-DOM fraction represented 70 to 94% of the total DOM pool. Inflow waters separated along the biophysical dimension of our PCA based on their photolability and bioavailability, driven by differences in the inflow water's DOM composition. UV exposure decreased humic and aromaticity proxies with concomitant photo-production of LMW compounds and increases in bioavailability proxies. Photo-exposure significantly decreased nitrate and dissolved organic carbon (DOC) concentrations for most of the sites and dissolved organic N (DON) for three of the eight sites, but no significant changes were noted for ammonia. One site exhibited an increase in nitrate with UV exposure and had DOM primarily from terrestrial origins. Spectroscopic indices, PARAFAC components, and amino acids provided corroborating evidence that further supported the differences in photo- and biolability at each inflow site, which is likely driven by their original DOM characteristics. PARAFAC components were correlated with dissolved organic P (DOP) and suggest that there may be adsorption of DOP with humic components in the LMW fraction. This work highlights the importance of photochemistry in the STAs, the complexity of DOM turnover in STA source waters, and the potential interactions between dissolved P and other DOM components, which may further influence the treatment efficiency of the STAs.

Could the hydrological conditions of Lake Baiyangdian support a booming metropolis?

In 2017, the Chinese government announced the development of another metropolis called Xiong'an New Area (XNA) to relieve the population and service pressures affecting Beijing. By the programs of the Chinese governments, the largest natural freshwater wetland of the XNA, Lake Baiyangdian (BYD), will provide the key ecosystem services for the region. However, whether the hydrological conditions of BYD can support this booming metropolis is still unclear. The hydrological condition evolutions and the ecological water demand of BYD in the near future were evaluated. The results showed that to maintain the ecosystem function of BYD and provide ecological services for the XNA, the annual ecological water demands of BYD ranged from 3.10 × 108 m3 to 6.35 × 108 m3 under different water exchange scenarios. Due to the insufficient water resources within the watershed, under the scenario of a 1.0 time year−1 frequency of lake water exchange, in wet years, normal flow years and dry years 1.32 × 108 m3, 2.10 × 108 m3 and 3.38 × 108 m3 of external water from the Yellow and Yangtze Rivers must be transferred into BYD to satisfy the ecological restoration of the XNA, and the costs may be as much as 77–277 million RMB (11.0–39.57 million USD) per year. The predicted results show that the external water demands may decrease slightly by 0.58 × 108–0.95 × 108 m3 year−1 and 1.02 × 108–1.19 × 108 m3 year−1 in the 2030s and 2050s, respectively. Agricultural water consumption reduction, inflow water quality improvement and the intelligent use and management of urban reclaimed water are necessary for maintaining the ecosystem function of BYD, and externally transferred water may be a potential factor needed to support the growing XNA.

Dynamics of radiocesium in an irrigation reservoir managed at low water level from the perspective of inflow and outflow water quality under non-flood conditions

Dynamics of radiocesium in an irrigation reservoir managed at low water level from the perspective of inflow and outflow water quality under non-flood conditions

Impacts of hydraulic retention time and inflow water quality on algal growth in a shallow lake supplied with reclaimed water

Landscape lakes supplied with reclaimed water often face the threats of algal blooms. To guarantee the water quality in an artificial shallow lake (Lake M), algal growth and water quality changes were predicted by Delft3D. When the concentrations of influent total nitrogen (TN) and total phosphorous (TP) were fixed at 10 ​mg ​N/L and 0.2 ​mg ​P/L, respectively, increases in the hydraulic retention time (HRT) which was induced by water depth increased algal growth. The average algal density in Lake M was 6.42 ​× ​104 ​cells/mL when the HRT was 4 ​d, which increased to 2.14 ​× ​105 ​cells/mL when the HRT was 8 ​d. These results showed that the shallowness of the lake contributed positively to algae control. The shallower water depth came with the shorter HRT while nutrient load and light intensity were increased subsequently, which usually favor algal growth but not the dominant factors of algal density in Lake M. When the influent TN concentration was between 2 and 15 ​mg ​N/L of which nitrate changed, the HRT was fixed at 8 ​d, and the influent TP concentration was 0.2 ​mg/L, the algal density was approximately 2 ​× ​105 ​cells/mL. Algae were not sensitive to changes in the influent TN concentration, and TN should be considered as a secondary factor in algal growth. Increases in the TP concentration promoted algal growth because phosphorous is the dominant nutrient for algae to acquire from reclaimed water if there is sufficient nitrogen. When the HRT of the lake was 8 ​d and the influent TN concentration was 10 ​mg/L, the average algal density in the lake was on the order of 104 ​cells/mL as the TP concentration was 0.1 ​mg/L. Because the water depth determines the HRT, it should be carefully considered during design and construction of artificial lakes. Influent phosphorus should be monitored to control algal blooms during maintenance of artificial lakes.

Microbial Community Structure of Activated Sludge and its Response to Environmental Factors

By mining and analyzing the published 16S rRNA amplification data of activated-sludge from 32 sewage and waste-water treatment facilities, at home and abroad, this study examines the microbial structure of sludge and its response to inflow water quality, temperature, and treatment type. Activated sludge generally shows high species diversity and community richness. Many activated sludge samples contain different microbial community structures. In these samples, the dominant bacteria included Thauera, Nitrospira, Comamonas, Dechloromonas, Rhodoferax, Aquihabitans, and Acidovorax. Temperature was negatively correlated with several key denitrifying microorganisms, such as Nitrospira, Aquihabitans, Terrimonas, and Dechloromona. When temperatures were lower than 15℃, the corresponding removal rates of TN and NH4+-N in the 32 sewage treatment plants only reached 49.67% and 63.19%, respectively. With higher BOD5/COD values, these sewage treatment systems exhibited improved biodegradability performances. With higher relative abundances of advantageous functional bacteria, such as Zoogloea, Arcobacter, Acidovorax, and Acinetobacter, pollutant-removal rates would increase accordingly. As for domestic-sewage treatments, the performance of the A2O process is superior to that of the OD, CAS, and CMAS processes. Additionally, the relative abundances of multiple functional dominant bacteria, including Comamonas, Rhodoferax, Nitrospira, and Novosphingobium, were significantly higher in sludge treated with the A2O process than in sludge treated with the other three processes.

하수처리수 재이용을 위한 수질 현황과 활용방안 연구

This study aimed to improve the reuse rate of reclaimed water by analyzing the water quality of inflow and discharge water and suggesting an reprocessing strategy for the reclaimed water from five sewage treatment plants in eastern Jeollanam-do. A total of 30 water quality parameters, including 16 general water quality and 14 heavy metal parameters, were analyzed following the water quality standards for reclaimed and discharged water. The results of the analysis confirmed that the reclaimed water from the Yeosu plant could be used for washing, waterhead and river maintenance water; the reclaimed water from Suncheon, Gwangyang Jungang and Gokseong for washing, waterhead, landscaping, and river maintenance; and the reclaimed water from Gwangyang for washing and waterhead. For the reclaimed water to be used for cleaning, toilet flushing, recreational use, or agricultural, an appropriate treatment method, such as chlorine disinfection, activated carbon adsorption, or reverse osmosis, needs to be selected to reprocess the reclaimed water after checking the water quality parameters. If the discharged water meets the water quality standards for reclaimed water, it can be reused or supplied immediately. Therefore, sewage treatment facilities should have a daily assessment of pH, turbidity, bound residual chlorine, odor, and color, weekly measurement of BOD, TN, TP, and total coliforms, and quarterly evaluation of chloride, electrical conductivity, and other heavy metals. These strategies will likely contribute significantly to increasing the reuse rate of reclaimed water.

Variation of water quantity, quality and pollutant flux of inflow and outflow rivers to Lake Taihu in Zhejiang Province, 2007-2019

自2007年太湖无锡水危机事件后，太湖流域内各项水污染防治工作进入快车道，近年来浙江省持续开展水环境治理，针对不同污染源进行分类施策、精准治理，整体水环境质量得到了显著改善.本文根据2007-2019年浙江省环太湖水文巡测资料及主要出入太湖河道水质监测成果，全面分析了出入湖河道的水量、水质及污染物通量的时空变化趋势.结果表明，2007-2019年浙江省年均入湖水量为27.39亿m3，年均出湖水量为26.42亿m3，环湖河道进出水量在2007-2014年以出湖为主，2015-2019年以入湖为主，2015-2019年入湖水量增加受该时段地区降水量较丰的影响.2007-2019年浙江省环湖河道CODMn、NH3-N和TP浓度呈明显下降趋势，TN浓度有所下降，除TN仍处于Ⅴ~劣Ⅴ类水外，其余指标已处于Ⅱ~Ⅲ类水标准，当前环湖河道的CODMn和NH3-N指标已达到《太湖流域水环境综合治理总体方案（2013年修编）》提出的目标值，但TN和TP浓度仍存在较大差距.浙江省环湖河道年平均CODMn、NH3-N、TP和TN入湖通量分别为1.12万、0.18万、0.03万和0.90万t，出湖通量分别为1.13万、0.10万、0.03万和0.62万t，环湖河道除CODMn以净出湖通量为主外，其余指标均以净入湖通量为主，存在一定入湖滞留，其中水量是影响入湖通量的关键因子.

Biosand Filter as a Point-of-Use Water Treatment Technology: Influence of Turbidity on Microorganism Removal Efficiency

The number of people living without access to clean water can be reduced by the implementation of point-of-use (POU) water treatment. Among POU treatment systems, the domestic biosand filter (BSF) stands out as a viable technology. However, the performance of the BSF varies with the inflow water quality characteristics, especially turbidity. In some locations, people have no choice but to treat raw water that has turbidity above recommended levels for the technology. This study aimed to measure the efficiency with which the BSF removes microorganisms from well water and from fecal-contaminated water with turbidity levels of 3, 25, and 50 NTU. Turbidity was controlled by the addition of kaolin to water. Turbidity removal varied from 88% to 99%. Reductions in total coliform (TC) and Escherichia coli ranged from 0.54–2.01 and 1.2–2.2 log removal values (LRV), respectively. The BSF that received water with a higher level of turbidity showed the greatest reduction in the concentration of microorganisms. Additional testing with water contaminated with four bacterial pure cultures showed reductions between 2.7 and 3.6 LRV. A higher reduction in microorganisms was achieved after 30–35 days in operation. Despite the filter’s high efficiency, the filtrates still had some microorganisms, and a disinfection POU treatment could be added to increase water safety.

СЕЗОННАЯ ДИНАМИКА ХИМИЧЕСКОГО СОСТАВА ВОД ОВРАЖНО-БАЛОЧНЫХ СИСТЕМ ГОРОДСКИХ ТЕРРИТОРИЙ (НА ПРИМЕРЕ САРАТОВА)

Актуальность исследования определяется необходимостью обеспечения экологического благополучия водных объектов в зоне воздействия крупных городов. В соответствии с современными природоохранными, экологическими и градостроительными требованиями водный сток с урбанизированных территорий не должен оказывать негативного воздействия на качество водных ресурсов. Цель: определение сезонной динамики (весенний максимум и летне-осенний минимум стока) поступления загрязняющих веществ с водным стоком оврагов и балок с территории города Саратова в Волгоградское водохранилище. Методы: морфометрический анализ водосборных бассейнов овражно-балочных комплексов; картографирование притоков естественного и техногенного происхождения; опробование вод в устьевых створах перед впадением в Волгоградское водохранилище; химический анализ состава поверхностных вод по приоритетным показателям по общепринятыми методикам (суммарно 140 определений); оценка и анализ качества вод относительно нормативов для водных объектов рыбохозяйственного значения. Результаты. Выполнена характеристика функционирования городских оврагов и балок; определены особенности формирования химического состава и транспорта вод по эрозионной сети урбанизированной территории; установлен состав вод десяти крупнейших овражно-балочных комплексов по приоритетным загрязняющим веществам для Волгоградского водохранилища (нитриты, железо общее, медь, цинк, сульфаты, азот аммония, нефтепродукты); в водном стоке обнаружены концентрации загрязняющих веществ, многократно превышающие установленные нормативы для водоемов рыбохозяйственного назначения. Качество водного стока не соответствует нормативам, установленным для водных объектов рыбохозяйственного значения, к которым относится Волгоградское водохранилище как часть волжского бассейна. В сезонной динамике химического состава вод не обнаруживается однонаправленных тенденций. Из 70 сравнительных пар проб весеннего и летне-осеннего стока снижение концентраций летом выявлено в 41 случае (58,6 %), повышение – в 21 (30 %), отсутствие изменений – в 8 (11,4 %). Контроль качества стока следует вести исходя из анализа конкретных водосборных бассейнов. Учитывая, что водохранилище служит источником централизованного хозяйственно-питьевого водоснабжения и объектом рекреационной деятельности, необходима организация систем очистки поверхностного водного стока.

Communication Strategy in Handling Customer Complaints in PDAM Tirta Pakuan Bogor

This study aims to 1) identify complaints that arise and do not satisfy customers, and 2) identify communication strategies undertaken by PDAM Tirta Pakuan in handling customer complaints. The study was conducted at PDAM Tirta Pakuan using qualitative descriptive analysis. Researchers surveyed customers and held focus group discussions with the management of PDAM Tirta Pakuan. The method of data analysis is done by using a gap analysis between performance and the interests/expectations of customers for product and service attributes, as well as public relations strategy theory. The results showed that there were four attributes that predominantly received complaints and were not yet satisfying customers, namely the quality of water flow in the dry season, replacement or re-measurement of water meters, compensation for service interruptions, and compensation for settlement of claims for paying bills. Furthermore, there are four communication strategies that are carried out in handling customer complaints based on four aspects, namely fact-finding, planning and programming aspects, action and communication aspects, and evaluating aspects. Some things that need attention from the management of PDAM Tirta Pakuan are 1) improving the quality of water supply during the dry season, 2) periodically replacing or repeating water meters, 3) improving the compensation system for customer service interruptions, 4) improving the compensation system related to the problem of settling claims for payment of claims, 5) identifying complaints that have the potential to threaten the image or reputation of the company, 6) maximizing the use of social media in informing work activities that have the potential to cause service disruptions and customer complaints. Keywords: communication strategies, customer complaints, public relations, service disruption, social media

Long-term data reveals the importance of hydraulic load and inflow water quality for Sb removal in boreal treatment peatlands

Antimony (Sb) is a common contaminant in natural peatlands used as treatment wetlands for water influenced by metal mining in cold-climate regions. However, while other metalloids such as arsenic have been well studied, little is known about removal and retention of Sb in northern wetlands under challenging environmental conditions. In this study we assessed short-term, long-term and seasonal variations in mobility, removal, and retention of Sb from mining-influenced water in two peat based natural wetlands with different loading and physical conditions. Analyses based on 10 years of water quality data and data on contaminant accumulation in the peat soil revealed that the wetland with significantly lower hydraulic load and Sb areal load achieved adequate Sb removal, but with a slight decline in recent years. Antimony concentrations at the wetland outlet were slightly lower in summers than in winters. Dilution due to high rainfall during summer may be the likely reason for low outlet concentrations towards the end of summer. Outlet Sb concentrations were on the rise after inlet water quality was significantly improved through enhanced pre-treatment indicating mobilization of accumulated Sb. In comparison, the smaller wetland with higher hydraulic and Sb loading had very low Sb removal and a stronger decrease in Sb concentration through dilution due to snowmelt. The results highlight the challenges in Sb retention which should get more attention when treatment wetlands are designed for Sb rich waters such as mine waters and there are changes in water treatment arrangement in specific cases.

Production, removal and fate of steroid estrogens under the background of total sewage interception in the Erhai Lake Basin, China

ABSTRACT The Erhai Lake basin dominated by agricultural production had a total sewage interception system and was selected as the study area. Survey data showed the total steroid estrogens (SEs) production was 55.97 kg/year (EEQ-E2β) in the whole basin and the main source of SEs was swine breeding (57%). The results indicated that unsatisfactory removal effect of SEs could be related to insufficient influent carbon sources as a result of the total sewage collection. The observed average concentrations of E1, E2α, E2β, E3 and EE2 in rivers/ditches were 25.9 ng/L, 43.5 ng/L, 14.4 ng/L, 49.4 ng/L and 24.5 ng/L, and SEs in ditches were significantly higher than that in rivers, proving the influence of the irrigation tailwater. Above, the annual SEs contribution for Erhai Lake was estimated, and the correlation coefficient of SEs and water quality of inflow rivers/ditches indicated that SEs had a certain correlation with nitrogen.

Correlation Analysis of Water Quality Between Lake Inflow and Outflow: A Case Study of Poyang Lake

The relationships between inflow and outflow water quality data for Poyang Lake from 1996 to 2016 are discussed and the main influencing factors are identified. TN and TP were the main factors causing a decline in water quality in Poyang Lake during the study period. The water quality of both the inflow and outflow rivers was generally good between 1996 and 2003; however, water quality declined over the study period, which is attributed to an increase in nutrients loads in the watershed. From 2004 to 2011, the water quality of the "Five Rivers" decreased significantly, which caused the water quality of Poyang Lake to decline. Due to the high purification capacity of Poyang Lake, the water quality of the outflow during this period was relatively good. A decline in water quality after this point was affected by pollution loads and hydrological conditions. Specifically, from 2012 to 2016, water quality in Poyang Lake and of the inflow water declined further. This was combined with a decrease in the water-purification capacity of the lake due to changes in the hydrological conditions, resulting in lower water quality at the outflow. Overall, the water quality of the inflow river has been closely related to the water quality in Poyang Lake. The concentrations of TN were significantly higher in the southern and eastern areas of Poyang Lake compared to the western areas. Higher nutrient loading from the Ganjiang River and the Xinjiang River has been an important driver. The concentrations of TP in the southern area of the lake have been significantly higher than in the eastern and western areas. This is attributed to comparatively high TP loads in the Ganjiang River and the Fuhe River. Compared to the changes in hydrological conditions, variations in nutrient loading have had a greater effect on water quality in the lake.

Impact of pH on the Treatment of Artificial Textile Wastewater Containing Azo Dyes Using Pond Systems

Two controlled experiments were operated to evaluate the impact of pH on the treatment efficiency of azo dyes within artificial textile wastewater using ponds as a polishing step. The objectives were to assess the (1) inflow water quality; (2) the presence of Lemna minor and the algae Oedogonium spp. on the dye removal and the outflow water quality; and (3) suitability of applying artificial textile wastewater and the impact of this wastewater and the dye on plants. Findings indicate that the shallow ponds planted with L. minor and/or algae treated the dye Basic Red 46 (BR46) significantly (p < 0.05) higher than the control ponds without any significant (p > 0.05) impact of pH. The potential of L. minor and algae for removal of BR46 was 31% and 25%, respectively. The removal of BR46 was around 89% for ponds planted with L. minor and algae, 58% for algae ponds and 33% for control ponds. Wetlands with L. minor are successful and economic in the complete degradation of BR46 at concentrations of 10 mg L−1 for any pH value between 6 and 9. The removal of ammonium-nitrogen (NH4-N), nitrate-nitrogen (NO3-N) and ortho-phosphate-phosphorus (PO4-P) was higher in planted than in unplanted ponds. The mean outflow values of chemical oxygen demand, NH4-N, NO3-N, suspended solids and total dissolved solids were within the limits for safe discharge. The artificial wastewater constituents after dilution (1 part of artificial wastewater to 24 parts of raw water) were suitable to use within the treatment system containing L. minor.

Study on the influence on water ecosystem by a lake inflow filtration system

Abstract. Lakes play important roles in the economic-social sustainable development. However, due to unreasonable development and urbanization in recent years, lake water pollution and ecological degradation have occurred in China. The improvement of the lake inflow water quality is very important. A filtration system includes Gravel filtering system, Aquatic plant area and Ecological bag area was established. The test river is one of the typical lake inflow river and located in the river network in the Chang Dang lake, China. Water quality, zooplankton and phytoplankton in the inflow river were observed form July to mid-August in order to analyze the general process. The average removal rate of NH3-N (ammonia nitrogen) TN (total nitrogen) and TP (total phosphorus) is 28.33, 25.76 and 24.43 %, respectively. The Pantle-Buck method was used to evaluate the water quality and the B∕T index was used to evaluate the nutrition situation. The B∕T values were reduced by 20 % and the SI pollution index was reduced by 11.8 %. Therefore, a positive effect on the water's ecological restoration was achieved by the filtration system.

Performance of surface and subsurface flow constructed wetlands treating eutrophic waters

Three medium size constructed wetlands (CWs) with a total surface of 90ha are working since 2009 in the Albufera de Valencia Natural Park (Spain). Two of them are fed with eutrophic waters from l'Albufera Lake. Their objectives are both reduce the phytoplankton biomass and increase the biodiversity; consequently, improved water quality is returned to the lake. A “science based governance” of these CWs is ongoing inside the LIFE+12 Albufera Project to demonstrate the environmental benefits of these features. In this paper, results and relationships among hydraulic operation, physicochemical variables and plankton in two different CWs typologies, five free water surface CW (FWSCW) and one horizontal subsurface flow CW (HSSFCW), were analysed showing that CWs were capable of improving the water quality and biodiversity but showing clear differences depending on the CW type. The CWs worked under different hydraulic load rates (HLR) from <0.12 to 54.75myr−1. Inflow water quality was typical from eutrophic waters with mean values of chlorophyll a (Chl a) about 22–90μgChlal−1 and mean total phosphorus (TP) between 0.122 and 0.337mgl−1. The main conclusion is that HSSFCW was much more efficient than FWSCW in the removal of organic matter, suspended solids and nutrients. The biological role of several shallow lagoons located at the end of the CWs has also been evaluated, showing that they contribute to increase the zooplankton biomass, a key factor to control the phytoplankton blooms.

Influence of spatial variation in land-use patterns and topography on water quality of the rivers inflowing to Fuxian Lake, a large deep lake in the plateau of southwestern China

With the development of agriculture, industry and urbanization, land-use and land-cover (LULC) change has resulted in significant deterioration of water quality and severe eutrophication in most of the lakes in China. Plateau lake ecosystem in China is very vulnerable and especially sensitive to environmental change and human disturbance, due to its strong closeness, species simplification, oligotrophy and simple food chain. This research focuses on evaluating the quantitative and spatial relationships of land use pattern and water quality of rivers inflowing to Fuxian Lake, China’s largest deep freshwater lake in plateau. To investigate the influence of spatial variation in land-use structures and topography on rivers water quality, the distributions of land-use types in the lake’s drainage basin were obtained from satellite images, and the correlations between land-use types and inflow water quality indicators were examined by applying statistical analysis and spatial analytical function of Geographic Information System. Subarea-level analysis reveals that a land-use type could exert different effects on water quality in plains and mountains, and the effects had a connection with topographic and hydrologic factors, its mixture with other land-use types, weather conditions during field measurements, as well as its scale. In addition, a comparison of correlation coefficient data for buffer regions of different scales indicated that the effect of land-use type on inflow water quality peaked in buffer regions with a radius between 100 and 200m. On the whole, the regions within 200m of river banks were the key regions that affected river water quality, and thus the construction and preservation of a riparian buffer zone in these regions can provide considerable protection from the inputs of non-point source pollutants and nutrients, and important function such as water and soil conservation. Based on these, a pollution control zoning was constructed from two key pollution control zones in the north and south, a phosphate rock pollution control zone in the northeast, a water loss and soil erosion control zone in the east, and a tourism pollution control zone in the west. This research also offers valuable insights into how to carry out subarea-level prevention and control of water pollution and regional development, according to natural environment, land use pattern and characteristics of pollution sources in different pollution control zones.

Response of Inflow Water Quality to Land Use Pattern in Northern Watershed of Lake Erhai

The inherent relationship between land use pattern and inflow water quality is essential for nonpoint source pollution study. Response of inflow river quality to land use pattern in Northern part of Lake Erhai Watershed was analyzed in aspects of land use composition and configuration using spatial analysis and statistical analysis methods. The results indicated that as land use composition indexes, average slope and vegetation area percentage had significant relationship with TN and TP of inflow rivers. As land use configuration indexes, patch density, patch density of agriculture land and landscape shape index of water had significant relationship with TP and NH4+-N of inflow rivers. Response of inflow river quality to land use pattern was better at class level than at landscape level. Water quality response indicators were TP in rainy season and NH4+-N in dry season, of which regression adjustment coefficient R2 was 0.761 and 0.978, respectively. Response of inflow river quality to land use pattern was better in dry season than in rainy season, and the water quality response indicators were TN, TP and NH4+-N. Improving vegetation coverage and agriculture land intensive degree and avoiding human disturb to natural water area especially in dry season were suggested in nonpoint source pollution control of northern watershed of Lake Erhai Watershed. Later research on relationship between land use configuration and inflow river quality should better be at class level.