Session 53 - Lakes, rivers, estuaries and ecosystem health

Algal blooms pertain to an undesirable formation of unicellular freely-floating algal scum caused by the rapid growth of phytoplankton, which can become a hazard for the water body ecosystem. Laguna Lake serves as both a source of livelihood and water supply for the residents in the region and the risk of algal blooms should be detected for safe and efficient management. The research presents a method for predicting the amount of phytoplankton to alert the monitoring agencies of incidences of high phytoplankton as a scalable and inexpensive early-warning tool. The study focuses on the development of a prediction model based on water quality parameters measured by the Laguna Lake Development Authority (LLDA) from 2008 to 2018: nitrate, orthophosphate, water temperature, turbidity, chlorophyll-a, and phytoplankton counts. The system predicts the phytoplankton counts of the next month using three months of previous values of the water quality parameters, modeled through the multilayer perceptron neural network method. The research uses a walk-forward validation method to obtain the root-mean-square-error (RMSE) of the model. The model was used on three stations and these predicted values that had statistically less RMSE than the ordinary least square regression.

Session: 53, Room: E, at Sat, 09/07/2019 - 15:45 to 16:00
Oral presentation in Lakes, rivers, estuaries and ecosystem health

Formation of artificial lakes is a common practice for hydroelectric power generation. Hydroelectricity is considered to be a green and renewable energy source in terms of factory operation. However, hydroelectricity generation may have environmental impact arisen from greenhouse gas (GHG) emissions induced by biomass degradation within water reservoir. Depending on area (rocks, cultivation fields, etc) flooded, an artificial lake may emit significant amounts of GHG, especially in the first years of its formation. In this study, the GHGs emission and water quality of two artificial lakes (Polyfytos and Ilarionas formatted in 1974 and 2012 respectively) and of one natural lake (Zazari) in the area of Western Macedonia were measured and evaluated. Results show that the old Polyfytos lake is stabilized and emits low amounts of CO2 (maximum flux 568 mg/m2/day) and zero CH4.The fresh Ilarionas lake and the natural lake emit higher amounts of CH4 (maximum fluxes 19 and 2200 mg/m2/day respectively). The CO2 emissions depend strongly on time of year and chlorophyll concentration in water (indicator of photosynthetic activity) and even negative fluxes were found in Ilarionas and Zazari (-395 and -732 mg/m2/day respectively). A simple model is used to correlate and predict future GHG emissions by the lakes.

Session: 53, Room: E, at Sat, 09/07/2019 - 15:30 to 15:45
Oral presentation in Lakes, rivers, estuaries and ecosystem health

Sediment as the product of erosion processes is found in every water body and reduces the storage capacity and the lifetime of water reservoirs. The quantity of sediment which affects downstream areas and also their quality complicate sediment management. Dredged sediments are on the borderline of soils, water and waste. The favourite dredged material management options are natural options. Beneficial re-use is a way to encourage the use of dredged material as a potential resource and not as a waste. Sediments are regarded as a suitable raw material in construction industry. This paper is focused on the study of the effect of sodium hydroxide as a pozzolanic activator of sediments from Ruzin reservoir (Slovakia) used as a binder in concrete on the compressive strength of hardened concrete. Reservoir sediments are mechano-chemically and chemically activated with the addition of solid sodium hydroxide into milling process. Hardened mixtures containing 40% of binder replacement by activated sediments were tested for compressive strengths after 28, 90 and 365 days of curing. The results show that sodium hydroxide is not an effective pozzolanic activator for sediments.

Session: 53, Room: E, at Sat, 09/07/2019 - 16:33 to 16:36
Flash presentation in Lakes, rivers, estuaries and ecosystem health

It is well documented that conservation and management of water resources are directly related to the sustainable living, i.e. to social, economic and environmental aspects. There has been much effort by the European research community to provide tools to support the implementation of freshwater sustainability and management policy instruments. In this context the DPSIR model was used as an analytical framework for determining pressures and impacts under the WFD as it is considered as an effective tool for both society and policy makers concerning water resources management. There is also an increasing interest about the importance of key ecosystem services in maintaining of human well being sustaining also water related services. Thus, there is much political and scientific drive to embrace the “Ecosystem Services” (ES) based approach. Based on the linking of these processes we present an integration of the DPSIR model with the ES concept using as case-study the River Nestos lagoons (Greece). According to the DPSIR approach the major driving forces leading to pressures were the agriculture, the irrigation, the unrestrained livestock, the industry and the urban wastewater. We outline the main changes in the State and in the Ecosystem Services which are essential to support sustainability. Our results show that integrating pressure analysis with Ecosystem Services we provide a useful tool for implementing management policies.

Session: 53, Room: E, at Sat, 09/07/2019 - 16:15 to 16:30
Oral presentation in Lakes, rivers, estuaries and ecosystem health

The main objective of this study was to assess the quality of water from five monitoring stations in Asopos River (central Greece), and evaluate the main factors that affect water quality. Fifty one biochemical parameters measured both in situ and in the laboratory three times a year for two consecutive years. Multivariate analysis of Hierarchical cluster analysis and Principal component analysis were used to interpret water quality characteristics. Cluster analysis grouped the samples in two main clusters (classes) corresponding to different main activities which affect water quality characteristics. The first cluster includes the two sampling stations located near the industrial areas and the second one the three stations located in areas affected by agricultural activities. Principal Component Analysis identified two factors which explain 84,5% of the variability of the original mean data set. The first factor explaining 50,5 % of the whole data variability related mainly to “chemical quality parameters”, while the second factor explaining 34% of total data variability related mainly to “biological quality parameters”. This study showed that multivariate statistical techniques proved effective in river water quality classification based on large and complex water quality data sets.

Session: 53, Room: E, at Sat, 09/07/2019 - 16:30 to 16:33
Flash presentation in Lakes, rivers, estuaries and ecosystem health

This study correlated the trophic condition of two Mediterranean water bodies with different typology with their water quality characteristics. The two studied cases included Polemidia Dam, a reservoir enriched with tertiary treated wastewater in Cyprus and Lake Karla, a re-established reservoir in Greece. The aim was to identify the key environmental variables driving cyanobacteria blooming and their cyanotoxicity and therefore to address effective management tools for each case. Monitoring data collected from both sites were analyzed using mathematical models (linear regression models) and statistical tools (Principal Component Analysis) in order to first correlate the water quality characteristics with the eutrophic state of the dam and to find which component mostly explains the variation in our dataset. As expected, temperature is not a limiting factor for bloom formation for both waterbodies. Among the variables tested, phosphorus (P) was found to be the key element for the growth of cyano-HABs in Lake Karla, while a significant reduction in the TP concentration of the recycled water used to enrich Polemidia reservoir following year 2010 altered the trends of cyano-HABs formation and their characteristics. It is anticipated that the outcomes of this study will assist in identifying the most challenging issues related to cyano-HABs in warm reservoirs in the near future conditions.

Session: 53, Room: E, at Sat, 09/07/2019 - 15:15 to 15:30
Oral presentation in Lakes, rivers, estuaries and ecosystem health

Flood risk prediction has been traditionally based on models that are developed from time-series of data collected over long periods of time from expensive and hard to maintain in situ sensors available only in specific areas. SCENT is a H2020 project which provides an integrated toolbox of smart collaborative and innovating technologies that augment costly in situ infrastructure, enabling citizens to become the ‘eyes’ of the policy makers by monitoring LC/LU changes in their everyday activities and related environmental phenomena like floods by crowdsourcing relevant information.
Policy makers and relevant stakeholders are able to set-up citizen science campaigns in areas where specific environmental information is needed. These data may include images that are processed through an intelligent engine and classified based on a LC/LU taxonomy, sensor measurements with low-cost portable environmental sensor or river measurements. The crowdsourced LC/LU information is used to created improved and more detailed maps of the area of interest where taxonomy elements such as river banks are identified and categorized base on their coverage, such as low grass and stone.
The produced LC/LU maps along with the sensor and river measurements are used to create flood models, used by public authorities and stakeholders to better understand the area of interest, its needs and the steps needed to support its sustainability.

Session: 53, Room: E, at Sat, 09/07/2019 - 16:00 to 16:15
Oral presentation in Lakes, rivers, estuaries and ecosystem health

The water quality of Kosynthos river, located in Xanthi Prefecture, Northern Greece, was evaluated using Water Quality Indices (WQIs). A water quantity and quality monitoring program was undertaken from December 2016 to November 2017 on a weekly basis at three stations along the main course of Kosynthos river. Discharge, temperature (T), dissolved oxygen (DO), pH and electrical conductivity (EC) were measured in situ. Moreover, water samples were collected and analyzed for the determination of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), total phosphorus (TP), and ammonium nitrogen (NH4-N), according to the standard methods. Anions (i.e., SO4-2, Cl-), NO3-N, NO2-N, and cations (i.e., Na+, K+, Mg+2, Ca+2) were determined using ion chromatography. The applied WQIs were the Canadian (CCME) WQI, the Oregon WQI, the National Sanitation Foundation (NSF) WQI and the Prati’s Index of Pollution. According to the CCME, NSF and Prati’s WQIs the water quality of Kosynthos river for both monitoring periods (e.g., 1998-1999 and 2016-2017) was classified in the higher quality classes, while according to the Oregon WQI it was classified in the lowest quality class.

Session: 53, Room: E, at Sat, 09/07/2019 - 15:00 to 15:15
Oral presentation in Lakes, rivers, estuaries and ecosystem health