Seasonality of the Basic Physical and Chemical Characteristics of Water Flowing through the Cascades of Small Reservoirs in Urban and Suburban Areas

The paper showed the changes of characteristics of river water flowing through the cascades of reservoirs. One of the cascades is located in a highly urbanized area of Lodz. The second is in a suburban area on the northern outskirts of Lodz agglomeration. However, it still remains under the influence of storm water discharged from the highway. Every 2 weeks, in 4 monitoring points (on the input and on the output of each cascade), the measurements of basic physical and chemical water parameters were made (using data registered in cross-sections obtained between 2006 and 2012). The analysed characteristics can be divided into three groups: 1. No changes in the seasonal fluctuations of analysed characteristics before and after the cascade of reservoirs and no differences between urban and suburban areas in the influence of the cascades on river water; 2. Significant changes in the seasonal fluctuations of analysed characteristics before and after the cascade of reservoirs and no differences between urban and suburban areas in the influence of the cascades on river water; 3. Significant changes in the seasonal fluctuations of analysed characteristics before and after the cascade of reservoirs and also significant differences between urban and suburban areas in the influence of the cascades on river water. The first group includes the temperature and pH of the water, the second group water conductivity and the third group water turbidity and dissolved oxygen in water.