Variability of the initial abstraction ratio in an urban and an agroforested catchment

The Curve Number method is one of the most commonly applied methods to describe the relationship between the direct runoff and storm rainfall depth. Due to its popularity and simplicity, it has been studied extensively. Less attention has been given to the dimensionless initial abstraction ratio, which is crucial for an accurate direct runoff estimation with the Curve Number. This ratio is most often assumed to be equal to 0.20, which was originally proposed by the method’s developers. In this work, storm events recorded in the years 2009–2017 in two small Polish catchments of different land use types (urban and agroforested) were analyzed for variability in the initial abstraction ratio across events, seasons, and land use type. Our results showed that: (i) estimated initial abstraction ratios varied between storm events and seasons, and were most often lower than the original value of 0.20; (ii) for large events, the initial abstraction ratio in the catchment approaches a constant value after the rainfall depth exceeds a certain threshold value. Thus, when using the Soil Conservation Service-Curve Number (SCS-CN) method, the initial abstraction ratio should be locally verified, and the conditions for the application of the suggested value of 0.20 should be established

Impact of runoff prediction on grey water footprint in a small agricultural catchment

According to Hoekstra et al. (2011) the water footprint within a geographic area is defined as the total freshwater consumption and pollution within the boundaries of the area. The grey part of the water footprint refers to pollution and is an indicator of the water volume needed to assimilate a pollutant load that reaches a water body. It is possible then, based on the grey water footprint to estimate if the water available in a river at a particular crosssection will be sufficient to maintain a water pollution level (WPL) below 100%. The crossing of 100% indicates that the waste assimilation capacity has been fully consumed in this particular catchment. In this paper, the grey water footprint from nonpoint source pollution has been calculated based on long-term hydrometrological data for the upper part of a small agricultural catchment (area of 23.4 km2 ) (Zagożdżonka River) in central Poland. Based on land use and the amount of fertilizers applied in the catchment, together with information about the natural concentration of nitrogen and phosphorus in the river, as well as maximum acceptable concentration, the water pollution level has been calculated for actual conditions. The estimation of future runoff decreases for the considered catchment (Banasik, Hejduk 2012) has been applied in order to estimate potential future water pollution levels. The calculation shows that, even when the management practices in this catchment remain as they are, including the current extensive crop production, the WPL of 100% will be exceeded in the year 2033 (for phosphorus) and 2043 (for nitrogen) due only to the decreasing availability of water

First Evidence of Microplastic Presence in Bed Load Sediments of a Small Urban Stream in Warsaw

Microplastics (MPs) are considered as a contaminant of widespread global concern. Due to their small size, MPs become bioavailable to many types of organisms and affect them. However, there is still little known about MP release on land, storage in soils and sediments, or their transport by runoff in rivers. Thus, the aim of this work was to present the results of the first, initial investigation on microplastic presence in an urban stream located in Warsaw, Poland. A simple and relatively inexpensive procedure that leads step-by-step to the detection of microplastics in bed load sediment is presented. It consists of sampling, sieving, density separation, organic matter reduction, and Nile Red staining. The presence of MP in the channel of Służew Creek was confirmed. The estimated amount of particles ranged from 191 to 279 pieces per 30 g of bed load sediment for the selected sampling sites. The number of particles seemed to increase with the catchment area. There is a need for further broad research focusing, among others, on the standardization of methods and laboratory procedures leading to microplastic detection

Hydrological Droughts in the Białowieża Primeval Forest, Poland, in the Years 1951–2020

The occurrence of hydrological drought, caused by rainfall deficiency, poses a threat to forest areas—not only due to the danger of fire, but as a result of changes in habitat conditions. It is predicted that more frequent periods of drought and high temperatures will reduce the stability of forests and increase their susceptibility to industrial pollution, pressure from insect pests, fungal pathogens, and fires. The main aim of this study was to investigate the current streamflow droughts in the catchment area of the Narewka River as an indicator of hydrological droughts in the Białowieża Primeval Forest for the period 1951–2020. The research presented in this paper shows that low flows of surface waters have appeared as an indicator of hydrological droughts almost every year since 1983. The analysis of the trend over the past 70 years shows that the aggregated annual volumes of low flows and the number of days with low flows are increasing significantly. This indicates a significant and relatively permanent change in the seasonal structure of the river runoff in the event of low summer flow

Dynamics of the Natural Afforestation Process of a Small Lowland Catchment and Its Possible Impact on Runoff Changes

Changes in land use have an impact on changes in renewable water resources. Land use especially in the context of urbanization has been and continues to be widely studied. The role of the forests in ecosystems is well known but there is not much research investigating the impact of natural afforestation on water resources. This paper shows the results of the quantitative changes in the use of the lowland catchment in the last 50 years on the example of the Zagożdżonka river located in central Poland. The results show that the impact of climatic factors on the reduction of water resources in the Zagożdżonka catchment is compounded by socio-economic changes in agriculture, and the positive role of forest areas in the catchment depends on the water demand of the stand. The interactions between forest ecosystems and water retention are strong and, depending on the habitat conditions, they may reduce ground runoff and deepen the water deficit in the catchment area in dry periods

Hydrological Droughts in the Białowieża Primeval Forest, Poland, in the Years 1951–2020

The occurrence of hydrological drought, caused by rainfall deficiency, poses a threat to forest areas—not only due to the danger of fire, but as a result of changes in habitat conditions. It is predicted that more frequent periods of drought and high temperatures will reduce the stability of forests and increase their susceptibility to industrial pollution, pressure from insect pests, fungal pathogens, and fires. The main aim of this study was to investigate the current streamflow droughts in the catchment area of the Narewka River as an indicator of hydrological droughts in the Białowieża Primeval Forest for the period 1951–2020. The research presented in this paper shows that low flows of surface waters have appeared as an indicator of hydrological droughts almost every year since 1983. The analysis of the trend over the past 70 years shows that the aggregated annual volumes of low flows and the number of days with low flows are increasing significantly. This indicates a significant and relatively permanent change in the seasonal structure of the river runoff in the event of low summer flow

INFLUENCE OF SELECTED FACTORS ON ERODIBILITY IN CATCHMENT SCALE ON THE BASIS OF FIELD INVESTIGATION

Drying of soil surface can affect the soil water repellency and reduce the infiltration, it may have impact on runoff and erosion. The aim of the research was to determine the effect of soil surface drying on its repellency and erosion, and the dependence of these values from the land use on the changing weather conditions background during the year. The research was conducted on Zagożdżonka river catchment, six times during the period of July 2014-September 2015, at five measuring points characterized by different land use. The irrigation of soil was carried out using rainfall simulator made by Eijkelkamp company. The intensity of the rain during the first 3 minutes of precipitation was 6 mm / min, the kinetic energy of rain was 72 J m-2. The surface runoff was collected into containers placed in the bottom of the rainfall simulator. Water Drop Penetration Time test was used to determine soil surface wettability. WET-2 probe was used to measure the moisture and soil temperature. Sediment concentration in the effluent was determined by weight method on filters. Variability of soil wettability was observed in different dates of measurements. Increasing repellency was recorded during the dry periods. The highest class of repellency was found in the forest and wild meadow areas. There was no direct correlation between the soil moisture, soil temperature and runoff. Both, sediment concentrations and sediment grain size, varied in the collected samples, depending on measurement time. The highest sediment concentrations were found in runoff from agricultural land use

Variability of the Initial Abstraction Ratio in an Urban and an Agroforested Catchment

The Curve Number method is one of the most commonly applied methods to describe the relationship between the direct runoff and storm rainfall depth. Due to its popularity and simplicity, it has been studied extensively. Less attention has been given to the dimensionless initial abstraction ratio, which is crucial for an accurate direct runoff estimation with the Curve Number. This ratio is most often assumed to be equal to 0.20, which was originally proposed by the method’s developers. In this work, storm events recorded in the years 2009–2017 in two small Polish catchments of different land use types (urban and agroforested) were analyzed for variability in the initial abstraction ratio across events, seasons, and land use type. Our results showed that: (i) estimated initial abstraction ratios varied between storm events and seasons, and were most often lower than the original value of 0.20; (ii) for large events, the initial abstraction ratio in the catchment approaches a constant value after the rainfall depth exceeds a certain threshold value. Thus, when using the Soil Conservation Service-Curve Number (SCS-CN) method, the initial abstraction ratio should be locally verified, and the conditions for the application of the suggested value of 0.20 should be established

Przepływy niżówkowe Wisły w Warszawie w XXI wieku

Celem pracy jest ocena zjawiska niżówki, będącej okresem utrzymywania się niskich stanów wody i przepływów w korycie rzeki. Analiza ich występowania w profilu Warszawa-Nadwilanówka na Wiśle, dotyczy początku XXI wieku, została wykonana w odniesieniu do wielolecia 1951–2000. W celu wyznaczenia niżówek na hydrogramach dobowych przepływów odcięto je za pomocą przepływu granicznego. Według przyjętego kryterium niżówki na Wiśle w Warszawie występują rzadko. Najdłuższa i najsurowsza pod względem deficytu odpływu była niżówka w 1951 roku. W ostatnich latach badanego wielolecia (2003, 2012, 2015) niżówki osiągnęły znaczne rozmiary, lecz nie były większe od dotychczas zaobserwowanej niżówki z 1951 roku. Od roku 1985 nie zanotowano niżówek zimowych