Adam Krajewski

The Curve Number method, developed in the 1950s in the United States, is commonly used to estimate runoff depth resulting from heavy rainfall. Over many years, it has been tested in various regions and for different purposes beyond its original use. Despite numerous studies on this method, some issues still require consideration, i.e., a universally accepted procedure for CN determination from rainfall-runoff data. In this work, the authors attempt to estimate the CN parameter for a small, lowland catchment in central Poland. Historical data on catchment land cover and original rainfall-runoff measurements are used to determine the CN for three periods of different catchment land cover structures. Approaches for CN estimation are compared and discussed. The study states that a) over the period 1974-2018, a gradual increase in forest areas is observed, while the average CN parameter dropped from 59.6 to 55.9; b) among considered approaches, the least-squares calibration is a straightforward concept, allowing for reliable estimation of CN from rainfall-runoff data; c) further research is still needed to focus on the influence of actual initial losses on Curve Number value.

The resistance of subfossil heartwood of European oak (Quercus robur L.) was examined in experiments conducted in accordance with the ASTM D 3345-08: 2009standard. The subfossil heartwood came from Dołhobrody (5100 +/-50 BC) and Pułtusk (13th–14th century). Subfossil heartwood of Q. robur is more susceptible to deterioration by subterranean termites than the recent heartwood of this species. The average weight losses of subfossil heartwood of oak were 0.306 g (Dołhobrody) and 0.475 g (Pułtusk). The average degree of damage to the subfossil heartwood was at the level of moderate attack, penetration. The differences in the degree of damage and weight losses of wood blocks for subfossil heartwood from Dołhobrody and Pułtusk were statistically insignificant. Termite mortality was slight grade (Pułtusk) or slight/moderate grade (Dołhobrody).

This article addresses the issue of droughts in recent years in Poland and their impact on the state of groundwater resources. This paper presents the challenges arising from the increasing demand for the use of groundwater for irrigation in agriculture, supplementing water shortages, and potential threats to the water supply of rural waterworks. The main part of this paper focuses on a small catchment area in the Mazovian Lowland, which is one of the driest regions in the country. This article includes definitions, characteristics, and causes of hydrologic and hydrogeologic droughts during the period 2011–2020. In the discussed area, there is generally one groundwater level of the Quaternary age, primarily recharged by rainfall infiltration, which is utilized by all dug wells and a number of drilled wells. The source material consisted of daily measurements of groundwater levels with a free surface from three piezometers located in different land use areas (forest, agricultural, and sparse development). Additionally, daily flows of the Zagożdżonka River at the Płachty Stare gauge station were examined, where the drying of the riverbed in the upper reaches has been observed in recent years. This study investigated the dynamics of hydrogeologic droughts in renewable groundwater resources and the rate of their decline in relation to hydrologic droughts of surface waters.

Predicting and estimating sediment yield from the catchment is crucial for the effective management of water resources and controlling soil erosion. Until now, Universal Soil Loss Equations (USLE) and their modifications are appreciated and commonly applied among many methods. The idea of this...

Small urban areas, due to their specificity (high anthroposphere, multiple forms of land use, variable drainage conditions), are often overlooked in studies on soil erosion and sediment transport that predominantly focus on a large scale. The sediment yield from such small urban areas may greatly vary depending, for example, on the state of the land development. Therefore, its proper estimation is crucial for water resources management, improving urban runoff quality or designing and maintaining local retention ponds. In this study, two different approaches were applied to estimate sediment yield from a small urban catchment of Służew Creek, located in Warsaw, Poland. While the first was based on direct hydrological measurements and field samples, the second (indirect) used various empirical formulas to predict bed load transport (local formula of Skibiński) in the stream channel and the suspended sediment delivery from the catchment (USLE equation, Build‐up/Wash‐off model). The sediment load established according to the direct approach equals 714 Mg/year, of which 83 Mg/year results from the bed load transport and 631 Mg/year comes from the suspended sediment transport. The total sediment load calculated according to the indirect approach equals 579 Mg/year. The relative difference in loads calculated with these two methods is about 20%. This paper combines various established methods into a novel composite analysis of sediment yield. The methodology presented in this study may support the estimation of sediment load in small urban catchments with a heterogenous land use structure. Hence, it may support urban planning and water resources management in such small catchments.

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.

The aims of this study are: i) to better understand the coupled interactions between land use changes, climate change and the aquatic ecosystem in a small agricultural catchment (2) with a long observation history (1963–2018) and a known land use history, and ii) to test available approaches to separate land use and climate change impacts on water resources in such a small catchment. The pre- and post-change periods have been separated based on change points and the known land use history. Next, conceptual and analytical approaches were applied to quantify and to distinguish between the impacts of climate and land use changes on annual runoff for these two periods. Over the observation period, both land use changes (increase in forest areas) as well as climate change (a temperature rise and a decrease in annual precipitation) occurred. These changes contributed to a decrease in the average annual runoff by 51.9 mm (49% of the long-term average) during the observation period. The quantified contributions of climate and land use changes to the decrease in the mean annual runoff amount to between 60% and 80% and between 40% and 20%, respectively. (i) The results obtained from different methods were consistent - a change in runoff was primarily caused by shifts in climatic variables. (ii) However, the quantified contributions varied depending on the method applied and the form of the Budyko curve. (iii) Thus, special care should be taken in relation to the selection of the Budyko curve for quantifying these changes. (iv) Knowledge of the water deficit sources can result in better planning of water resources management in such small catchments.

Purpose: A novel concept of suspended sediment (SS) routing through a small reservoir is proposed that relies on the particle properties in the reservoir inflow. Methods: The SS routing through the reservoir is described following the single continuous stirred tank reactor concept with only one model parameter, the SS decay coefficient. This parameter is linked to the sediment settling velocity and water flow velocity. Hence, the model does not require a direct calibration with recorded data. This model was tested on a small reservoir in Warsaw, Poland, with seven storm events. Suspended sediment samples at the reservoir inflow and outflow were taken manually during the passage of flood flows at irregular intervals. The performance of the proposed method was verified with the approach when the model parameter is estimated directly from recorded events. Results: The parameter calculated based on particle properties was about 10 times higher than the corresponding parameter optimized from recorded SS events. Hence, there was a need to introduce a correction factor to accurately predict the effluent SS. This led to a high model performance for all events (Nash-Sutcliffe = 0.672 on average). Conclusions: (i) The proposed SS routing model based on particle properties has been proven to accurately simulate SS in the reservoir outlet. (ii) Thus, the parameter can be estimated from the sediment settling velocity and water flow velocity, but the correction factor must be applied. (iii) Our findings acknowledge difficulties in describing SS routing through small reservoirs and indicate a lack of knowledge on the functioning of these reservoirs.

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.