Statistical and trend analysis of water quality and quantity data for the Strymon River in Greece

Abstract

Strymon is a transboundary river of Greece, Bulgaria and Former Yugoslav Republic of Macedonia (FYROM) in southeastern Europe. Water quality parameters and the discharge have been monitored each month just 10 km downstream of the river's entry into Greece. The data of nine water quality variables (T, ECw, DO, SO 4 2-, Na + +K + , Mg 2+ , Ca 2+ , NO 3 -, TP) and the discharge for the period 1980-1997 were selected for this analysis. In this paper a) the time series of monthly values of water quality parameters and the discharge were analysed using statistical methods, b) the existence of trends and the evaluation of the best fitted models were performed and c) the relationships between concentration and loads of constituents both with the discharge were also examined. Boxplots for summarising the distribution of a data set were used. The χ 2 -test and the Kolmogorov-Smirnov test were used to select the theoretical distribution which best fitted the data. Simple regression was used to examine the concentration-discharge and the load-discharge relationships. According to the correlation coefficient (r) values the relation between concentrations and discharge is weak (r< 0.592) while the relation between loads and discharge is very strong (r>0.902). Trends were detected using the nonparametric Spearman's criterion upon the data for the variables: Q, ECw, DO, SO 4 2-, Na + +K + and NO 3 -on which temporal trend analysis was performed.

Water Quality Assessment and Apportionment of Pollution Sources of Selected Pollutants in the Min Jiang, a Headwater Tributary of The Yangtze River

“…Due to the complexity of water environments, water quality specialists and decision-makers are confronted with significant challenges in their efforts to manage surface water resources [2]. Therefore, identifying temporal and spatial changes in water quality in river basins is an imperative task, so as to provide an improved understanding of the environmental conditions and help researchers establish priorities for sustainable water management [3][4][5][6].…”

Rank regression analysis of correlated water quality data from South East Queensland

“…Traditionally, the linear regression model is used to test whether an explanatory variable significantly affects the water quality indicator. For example, Antonopoulos et al (2001) proposed using the regression models to examine the relationship between concentration-discharge and load-discharge. Carlson et al (2002) used the linear regression models to explore which environmental variables most affect water quality indicators in Silver Lake and Casey Lake in Unite States.…”

How Do Terrestrial Determinants Impact the Response of Water Quality to Climate Drivers?—An Elasticity Perspective on the Water–Land–Climate Nexus

“…Trend analysis gained attention in environment studies, especially water quality, owing to the availability of sufficient water quality records [41,42]. Here, monotonic trends in water quality parameters based on rank based nonparametric Spearman's test were assessed [41,43] and fitted to linear, logarithmic, quadratic, power and exponential models [44,45]. The best fitted model was selected for each variable based on coefficient of determination (R 2 ) value.…”