Green roofs play a significant role in sustainable drainage systems. They form absorbent surfaces for rainwater, which they retain with the aid of profile and plants. Such roofs therefore take an active part in improving the climatic conditions of a city and, more broadly, the water balance of urbanized areas. One of the factors influencing the hydrological efficiency of green roofs is the drainage layer. In the article, column studies were carried out under field conditions involving the comparison of the retention abilities of two aggregates serving as the drainage layer of green roofs, i.e. Leca® and quartzite grit. The average retention of the substrate was 48%; for a 5 cm drainage layer of Leca® retention was 57%, for a 10 cm layer of Leca average retention was 61%. For a 5 cm layer of quartzite grit average retention was 50%, for 10 cm layer of quartzite grit 53%. The highest retention was obtained for the column with the substrate and 10-centimeter layer of Leca®. At the same time, it was shown that Leca® is a better retention material than quartzite grit. The initial state of substrate moisture content from a green roof appears to be a significant factor in reducing rainfall runoff from a green roof; the ob-tained values of initial moisture content made for a higher correlation than the antecedent dry weather period.

This paper presents the permeability of the permafrost active layer determined in the Brattegg River catchment (SW Spitsbergen) for the 6-years interval of 2005–2010. The field permeability measurements technique of weathered rocks on various geomorphological forms allows to assess the value of their hydraulic conductivity ( k). High variability of k values, ranging from 6.37 10 ⁻⁹ to 4.0 10 ⁻³ m s ⁻¹, indicates the permeability of rocks from very low in clay to very high in gravel-rock rubble. Among the geomorphological forms, the best permeability was observed in boulder covers and rock debris, and the lowest one in patterned ground. The obtained results were used to determine the groundwater runoff ( q), assuming the unit thickness of the active layer aquifer. The q value from the Brattegg River catchment was calculated at 130 L s−1, which is from 15% to 47% of the average surface runoff.

The paper discusses the water resources of the Krężniczanka River catchment. The catchment with an area of 224.9 km2 is located south-west of Lublin. The characteristics of the groundwaters and runoff were determined based on hydrological and hydrogeological materials of the Department of Hydrology of the Maria Curie-Skłodowska University (UMCS). Mean runoff in the period from 2010 to 2016 amounted to 125.7 mm, precipitation 629.4 mm, and evapotranspi-ration 503.7 mm. A strong relationship was determined between the rhythm of runoff and ground-water level fluctuations. The contribution of groundwater supply in total runoff equalled 81.5%.

Runoff estimation is a key component in various hydrological considerations. Estimation of storm runoff is especially important for the effective design of hydraulic and road structures, for the flood flow management, as well as for the analysis of land use changes, i.e. urbanization or low impact development of urban areas. The curve number (CN) method, developed by Soil Conservation Service (SCS) of the U.S. Department of Agriculture for predicting the flood runoff depth from ungauged catchments, has been in continuous use for ca. 60 years. This method has not been extensively tested in Poland, especially in small urban catchments, because of lack of data. In this study, 39 rainfall-runoff events, collected during four years (2009–2012) in a small (A=28.7 km2), urban catchment of Służew Creek in southwest part of Warsaw were used, with the aim of determining the CNs and to check its applicability to ungauged urban areas. The parameters CN, estimated empirically, vary from 65.1 to 95.0, decreasing with rainfall size and, when sorted rainfall and runoff separately, reaching the value from 67 to 74 for large rainfall events.

This study presents the results of tests conducted in 2009 and 2010 on experimental sites installed on the roof of the Science and Education Building of the Wroclaw University of Environmental and Life Sciences. The aim of the analysis was to determine the retention capacity of green roofs and the runoff delays and peak runoff reduction during rainfall recorded in Wroclaw conditions.

The research shows that green roofs allow to reduce the volume of runoff stormwater in comparison to conventional roofs, that they delay the runoff in time and influence the reduction of the maximum runoff intensity, and thus may limit the impact of stormwater on the stormwater drainage and combined sewage systems.

Time of concentration, Tc, is defined as time elapsed from the beginning of rainfall infiltrated into soil layer until it reaches a constant infiltration rate (fc) which is indicated an equilibrium subsurface flow rate. In hydrological view, time of concentration plays a significant role in elaboration of transformation of rainfall into runoff in a watershed. The aims of this research are to define influence of soil density and soil water content in determining time of concentration using infiltration concept based on water balance theory, and to find out the effect of land slope this time. Watershed laboratory experiment using rainfall simulator was employed to examine time of concentration associated with infiltration process under different slope, soil density and soil water content based on water balance concept. The steady rainfall intensity was simulated using sprinklers which produced 2 dm3∙min–1. Rainfall, runoff and infiltration analysis were carried out at laboratory experiment on soil media with varied of soil density (d) and soil water content (w), where variation of land slopes (s) were designed in three land slopes 2, 3 and 4%. The results show that relationship between soil density and land slope to time of concentra-tion showed a quadratic positive relationship where the higher the soil density address to the longer time of concentration. Moreover, time of concentration had an inverse relationship with soil water content and land slope that means time of con-centration decreased when the soil water content increased.

Rain gardens are one of the best measures for rainfall runoff and pollutant abatement in sponge city construction. The rain garden system was designed and developed for the problem of severely impeded urban water circulation. The rain gardens monitored the rainfall runoff abatement and pollutant removal capacity for 46 sessions from January 2018 to December 2019. Based on these data, the impact of rain gardens on runoff abatement rate and pollutant removal rate was studied. The results obtained indicated that the rain garden on the runoff abatement rate reached 82.5%, except with extreme rainfall, all fields of rainfall can be effectively abated. The removal rate of suspended solid particles was the highest, followed by total nitrogen and total phosphorus, the total removal rate in 66.35% above. The rain garden is still in the “youth stage”, and all aspects of the operation effect are good.

Hydrological models are widely used for runoff simulation throughout the world. The objective of this study is to check the performance of the HEC-HMS model for continuous runoff simulation of Gilgel Gibe watershed. It includes sensitivity analysis, calibration, and validation. The model calibration was conducted with data from the year 1991 to 2002 and validated for the year 2003 to 2013 period using daily observed stream flow near the outlet of the watershed. To check the consistency of the model, both the calibration and validation periods were divided into two phases. The sensitivity analysis of parameters showed that curve number (CN) and wave travel time (K) were the most sensitive, whereas channel storage coefficient (x) and lag time (tlag) were moderately sensitive. The model performance measured using Nash–Sutcliff Efficiency (NSE), Percentage of Bias (PBIAS), correlation coefficient (R2), root mean square error (RMSE), and Percentage Error in Peak (PEP). The respective values were 0.795, 8.225%, 0.916, 27.105 m3 s–1 and 7.789% during calibration, and 0.795, 23.015%, 0.916, 29.548 m3 s–1 and –19.698% during validation. The result indicates that the HEC-HMS model well estimated the daily runoff and peak discharge of Gilgel Gibe watershed. Hence, the model is recommended for continuous runoff simulation of Gilgel Gibe watershed. The study will be helpful for efficient water resources and watershed management for Gilgel Gibe watershed. It can also be used as a reference or an input for any future hydrological investigations in the nearby un-gauged or poorly gauged watershed.

Flood inundation processes in urban areas are primarily affected by artificial factors such as drainage facilities, local al-terations of topography and land uses. The objective of this study is to examine the capability of hydrological model SI-MODAS to estimate runoff and investigating the utilization of storage well in controlling runoff in a residential area. The result of the estimated runoff from the hydrological model was compared with the existing capacity of the drainage channel to identify which channel experienced the problem of inundation. The location of inundation was used to determine the location and number of storage well. The results showed that SIMODAS model could be applied in runoff analyses with 8.09% of relative error compared with runoff depth from field measurement. The existing capacity of the channel could not accommodate runoff Q10yr where the inundation discharge was approximately 0.24 m3·s–1 (at outlet point 1) and 0.12 m3·s–1 (at outlet point 2). The inundation problem was overcome by using a combination system between channel normalization (reduce 35% of total inundation discharge) and storage well system (reduce 65% of total inundation discharge). The storage well was designed at 20 locations (at outlet point 1) and 16 locations (at outlet point 2) which each well had a discharge of 0.0058 m3·s–1. The storage well combined with channel normalization could be used as an alternative way to solve inunda-tion problems in a residential area considering the constraint of land space limitation in the urban area.

The study covered water resources of two mountain streams in the Polish Carpathians. These were the Biała Woda and Czarna Woda streams, the catchments of which are adjacent to each other. Water flows in both streams were measured during the hydrological years from 2006 to 2020. Next, water outflows from the catchments were calculated. The study aimed to determine differences in the water resources of those catchments in a very small mountainous area. The study showed quantitative similarity in water resources in the entire multi-annual period but at the same time large differences in shorter periods. Instantaneous and daily outflows showed the largest differences, but differences in annual outflows of up to 20% were also recorded. Therefore, hydrological data from operational cross-sections to assess water resources of neighbouring uncontrolled watercourses should cover multi-annual mean values. It was found that during periods of increased runoff (from melting snow or precipitation), the outflow from the Biała Woda catchment was much larger, while during rain-free periods, the outflow from the Czarna Woda catchment prevailed. All short- term flood like outflows were at least several tens of per cent higher in the Biała Woda catchment. The higher retention capacity of the Czarna Woda catchment can be attributed to the land use (mainly forest areas). The results can be used for modelling catchments of similar parameters and determining their retention capacity.

The exceptionally high spatial-temporal variability of the river runoff and the significance of its transboundary component considerably worsen the problem of the water supply of the republic. Due to the disadvantageous geographical location in the lower reaches of transboundary river basins, the Republic of Kazakhstan is largely dependent on water economy activities taking place in neighbouring countries. In the article the modern change of the resources of river runoff in Kazakhstan, taking into account climatic and anthropogenic influences is considered. For the assessment of the impact of economic activities on the river runoff and changes in climatic-related runoff, the complex of integral methods was used, and appropriate methodologies were developed. The obtained results of the modern influence of a complex of factors, as well as their significance for the future (till 2030), can be used for the development of scientifically based solutions for sustainable management and protection of water resources. An assessment of the anthropogenic activity of this study shows that the water resources of the river runoff of the Republic of Kazakhstan have decreased by 16.0 km ³∙y ^–1. According to our forecasts, there will be a further decrease in the water resources of the republic due to the expected decrease in transboundary flow to 87.1 km ³∙y ^–1 by 2030, in dry years less than 50.0 km ³∙y ^–1. We propose a set of measures to prevent the negative impact of possible reduction of river runoff resources in the future in the water basins of Kazakhstan.

In the 2008 ablation season, subglacial springs discharge, flow rate and profiling of the proglacial river, physical-chemical parameters (pH, temperature, electrical conductivity) and chemical composition (HCO3−, SO42−, Cl−, NO3−, NO2−, PO43−, Ca2+, Mg2+, Na+, K+, Fetot, Mn2+, Al3+, Zn2+, Pb2+ and SiO2) of water in the Werenskiold Glacier forefield were measured. Chemical composition of groundwater as well as water of lakes, the main watercourse, subglacial outflows and water representing direct meltwater recharge were studied to determine their origin, the depth of circulation and recharge systems. The results indicate that the main source of water in the glacial river were the subglacial outflows in the central part of the glacier. They generated 77% of the total amount of water in the glacier forefield. Direct inflow of groundwater from glacier moraine to proglacial river was marginally low and the water circulation system was shallow, fast and variable. There were no evidences for an important role of deeper than suprapermafrost water circulation systems. The water temperature, especially in the lakes, exceeding the mean daily air temperature during the ablation period, is due to the heating of the ground moraine rocks. A clear difference between groundwater chemical composition and surface water as well as subglacial runoff in terms of major ions, together with the homogeneity of chemical composition of the proglacial river from spring to mouth confirmed the marginal role of groundwater runoff in the drainage of the catchment area. It was confirmed that the chemical composition of groundwater and moraine lakes in the glacier forefield was shaped by geological factors, i.e., mainly chemical weathering of sulphides, carbonates and secondary sulphates. The possibility of secondary iron hydroxide precipitation and a high probability of complex aluminosilicate transformations were also demonstrated.

The goal of the presented research works is to prove the following thesis: Does the process of contaminants reduction and effiuent application for arable land fertilization justify the treatment method of waste water from a yeast production facility in soil and plant environment. In order to achieve the above mentioned goal, basically the dynamics of physical and chemical properties change observed for waters, soils and plants irrigated with wastewater from yeast factory has been studied for many years. Part I presented the problems characteristics of production as well as water and wastewater management in the yeast factory, principles and technological effectiveness of the treatment of process wastewater from yeast production in soil - plant environment and impact of irrigation with wastewater on water purity. The research proved that very high biological treatment indices are achieved on the Silesian Yeast Factory fields where process wastewater is utilized i.e. concentration reduction for: BOD5 - 99.3% and COD - 99.7%, - for eutrophic compounds: N,0,.1 - 98.83%, P - 96.25% and K - 99.18%. The obtained percentage of concentration reduction is higher than the standards assumed in the water supply and wastewater discharge consent issued to the factory. The drainage water from the fields irrigated with yeast effluent is of I, II and III class of purity.

Green roofs are increasingly popular in both new and modernised buildings. They significantly reduce the outflow of stormwater from buildings and change its composition. Wherever an urbanised area is equipped with a separate sewage system, usually stormwater goes directly to the receiver without treatment, which may affect the quality of water in the receiver. The article presents results of research carried out on the green roof of a building in Lodz, Poland. During rainfall, the flow rate from the roof was measured. With the use of the US EPA software Stormwater Management Model (SWMM) a model of the green roof was created and calibrated using rainfall data from the city’s pluviometric network. Based on the measurements of the roof runoff, as well as SWMM modelling, the degree of outfall reduction was determined. Samples of roof runoff were collected to study the characteristics of rainwater, including pH, electrical conductivity, organic compounds, nitrogen, phosphorus, and suspended solids. The results were compared with the quality of runoff from a traditional roof. Except ammonium nitrogen, values of the examined quality indicators was higher in the case of the green roof but the pollution load of almost all contaminants, except phosphorus, were lower due to a significant reduction in the volume of stormwater outflow (62–91%). The quality of stormwater discharged from the green roof improved with its age.

The runoff coefficient is one of the fundamental hydrological characteristics of a catchment. It indicates a share of the precipitation water that runs off from the catchment.

The results of the runoff coefficient calculation based on measurements carried out continuously in the Cerhovický Stream catchment over a considerable period of time, i.e. from 1988 up to 2006 are presented. The precipitation and runoff data in the catchment were used. Mean value of the runoff coefficient and the runoff coefficients for the agricultural and forest parts of the catchment are presented. The total mean runoff coefficient for the Cerhovický Stream is 0.19 with the standard deviation of 0.06. Mean runoff coefficient for the forest part is 0.13 and for the agricultural part – 0.24.

Differences between the years with a higher and a lower precipitation were followed as well. We also statistically evaluated possible hydrological changes caused by the construction of the highway and the market centre. For another possible explanation of quite high standard deviation of the mean annual runoff coefficient we followed the monthly runoff coefficient dependence on water temperature and of ground water table depth.

The objectives of developing oil palm plantations should feasible economically and without causing massive erosion. This research proposes soil and water conservation strategies that are ideal and optimal for oil palm cultivation depending on land capability class. The conservation test for plants was performed according to land capability classes on a plot measuring 22 m × 4 m. Runoff and erosion rates were measured using Multislot Divisor Method. Nutrient leaching was analysed based on the content of C-organic (Ctot) (Walkley–Black method), total nitrogen (Ntot) (Kjeldahl method), P-available (Bray-1 method) and K2O (extraction with 1N NH4OAc at pH 7.0). From the results, land capability class III, cover crops (soybean) + manure (P3) treatment effectively reduced runoff and soil erosion (22.63 m3∙ha–1∙y–1 and 13.04 Mg∙ha–1∙y–1), as well as nutrient leaching, compared to other treatments. Furthermore, sediment trap + cover crop + manure (P3) controlled runoff, erosion and nutrient leaching on land capability class IV, producing the lowest runoff (129.40 m3∙ha–1∙y–1), soil erosion (11.39 Mg∙ha–1∙y–1), C-organic (1.3%), and P (1.95 mg kg–1). Soil conservation treatment significantly reduced erosion and runoff (p < 0.05) on land capability class VI. The bench terrace + cover plants + manure treatment-controlled runoff, erosion, and soil nutrient leaching.

European cities face urban, demographic and climate challenges. According to forecasts, annual extreme phenomena will intensify – including torrential rains. Comprehensive solutions (also those based on nature), climate adaptation strategies, runoff management, incorporation of new design (e.g. sponge cities) are urgently required in order to strengthen urban resilience and to minimise the effects of extreme weather events (droughts, floods or heat islands).
The aim of the research was to develop a methodology for activating selected elements of blue-green infrastructure within areas of natural and cultural protection as an adaptive tool of urban planning. Modelling of infiltration possibilities, programmed with SCALGO Live Poland software, was performed as a case study based on a research city – Sandomierz (in Poland). Selected parameters (stormwater surface runoff, chosen runoff areas, land cover) are strongly correlated with urban indicators relating to the vegetation coverage (biologically active area – BAA).
Results pointed out urban units, which BAA is lower than 25% (e.g. Old Town Square, courtyards of tenement houses). Modelling was carried out for these units by concentrating on the undeveloped area for which the BAA was increased. The enhancement assumed values in the range of 41–45%. In analysed cases, an improvement (decrease) in runoff volume was obtained, even by 8.69%. Simultaneously, infiltration increased by 19.61%, calculated over entire runoff area. Implementation of solutions based on these results, in the form of appropriate planning provisions, can raise the quality of environment (e.g. improving water infiltration) and life (e.g. more effective air cooling on hot nights).

Over the past two decades, artificial neural networks (ANN) have exhibited a significant progress in predicting and modeling non-linear hydrological applications, such as the rainfall-runoff process which can provide useful contribution to water resources planning and management. This research aims to test the practicability of using ANNs with various input configurations to model the rainfall-runoff relationship in the Seybouse basin located in a semi-arid region in Algeria. Initially, the ANNs were developed for six sub-basins, and then for the complete watershed, considering four different input configurations. The 1st (ANN IP) considers only precipitation as an input variable for the daily flow simulation. The 2nd (ANN II) considers the 2nd variable in the model input with precipitation; it is one of the meteorological parameters (evapotranspiration, temperature, humidity, or wind speed). The third (ANN IIIP,T,HUM) considers a combination of temperature, humidity, and precipitation. The last (ANN VP,ET,T,HUM,Vw) consists in collating different meteorological parameters with precipitation as an input variable. ANN models are made for the whole basin with the same configurations as specified above. Better flow simulations were provided by (ANN IIP,T) and (ANN IIP,Vw) for the two stations of Medjez-Amar II and Bordj-Sabath, respectively. However, the (ANN VP,ET,T,HUM,Vw)’s application for the other stations and also for the entire basin reflects a strategy for the flow simulation and shows enhancement in the prediction accuracy over the other models studied. This has shown and confirmed that the more input variables, as more efficient the ANN model is.