Soil erosion by water is one of the most important morphogenetic processes taking place within the lowland geoecosystems in Poland. Therefore, it is relevant to recognise its nature, course, conditions and dynamics. This article presents some lithological conditions of water soil erosion on a testing plot within the Chwalimski Potok catchment in the Drawskie Lakeland. The conducted measurements of soil particle size distribution, soil moisture and compaction, shear strength and degree,  as well as infiltration rate constitute the basis of the analysis and all relevant calculations. It was shown that topsoil (slightly loamy sands) with increased humidity at the surface is most susceptible to the process of soil erosion by water. Some methods to prevent adverse degradation processes were suggested in the article.

The endorheic catchment of Lake Gardno is located in  northwestern Poland on the Wolin Island at a distance of 0.2 km from the Baltic Sea cliff coast. Within the Lake Gardno catchment, on a monthly basis, water with its quantitative aspects and physicochemical properties was examined at every stage of its circulation. For the diagnosis of the circulation of water and solutes, as well asits mechanisms it was essential to determine the seasonal variability of the concentration of biogenic (NO₃^-, NH₄⁺, K⁺) and denudative ions (HCO₃^-, SO₄^2-, Ca²⁺, Mg²⁺), and ions supplied primarily from sea aerosols (Cl^-, Na⁺). At the first stage of the water cycle, atmospheric water reaching tree-tops has the lowest mineralization at 1.8  mS·m^–1. Throughfall and stemflow lead to an increase in the mineralization up to 8.7  mS·m^–1 on average. The next stage, connected with the underground water circulation and leaching of soils, increases the mineralization of water up to 46.3  mS·m^–1. The lake water was mineralized at 36.7  mS·m^–1. The seasonal variability of the hydrochemical activity of water circulating within the Lake Gardno geoecosystem was represented by groups: with increased concentrations of solutes, with average concentrations of solutes and with reduced concentrations of solutes. The analyzed geoecosystem is characterized by a high concentration level of chloride and sodium ions at every stage of water circulation, which is related to the supply of sea aerosols.

Drainage of groundwater by surface water, i.e. groundwater inflow into a stream or lake, is an essential component of the water balance. Moreover, the drainage and its spatial distribution determine geomorphological processes taking place in the riverbed. In order to identify the spatial distribution of groundwater inflow into the river, prototypes of two new meters filtrometer and gradientmeter) were designed and developed. The filtrometer allows to directly measure the groundwater-surface water seepage through bottom sediments at the place where the meter is embedded into the riverbed. The gradientmeter allows to measure hydraulic gradient within bottom sediments between groundwater and the river. Both parameters measured directly in the riverbed allow to specify the conditions of groundwater flow through bottom sediments. The field research studies conducted by means of the specified meters (filtrometer and gradientmeter) within the Parsęta River valley at Storkowo were aimed to investigate the drainage of groundwater and its conditions. A section of the Parsęta River with a length of 1600 meters and having no tributaries was selected. Three series of field measurements: spring, summer and autumn ones were conducted. During each series approximately 30 measurements were made by means of the filtrometer and the gradientmeter. The conducted measurements made it possible to calculate flow rates of the drainage of groundwater within the examined section of the Parsęta. The obtained results were verified on the basis of control measurements with the application of the differential river flow method. Moreover, it was possible to assess the spatial distribution of specific discharge, hydraulic gradient and hydraulic conductivity in bottom sediments of the Parsęta. On an annual basis, the largest drainage of groundwater was found within meander erosive areas where it reached nearly 150% of the average value for the examined section within the Parsęta valley. Within meander accumulative areas, the drainage level was at approximately 110% of the average value. At straight sections the drainage of groundwater was the lowest and amounted about 66% of the average value. The research studies conducted in the Parsęta valley confirmed the usefulness of the new method to assess the drainage of groundwater and its conditions within the river.

The article contains an analysis of the duration and the dates of the start of thermal seasons of the year, distinguishedon the basis of the average daily air temperature at the Institute of Geography and Spatial Organization Research Station at Szymbark over a period of 46 years (1968-2013). To determine the initial dates of thermal seasons a method proposed by Makowiec (1983) was used. According to this method, the year was divided into eight thermal seasons, with temperature threshold values: 0, 5, 10 and 15 ° C. The classification by Makowiec is based on the growth or fall of cumulative ranks of air temperature diminished by the temperature threshold value for a particular season. The determination of the initial dates enabled the calculation of the length of the seasons. The long-term analysis involved also the tendencies of length and changes of the initial date of a given season. The location of the meteorological station enables to expand the area of the interpretation of results into the borderland of the Beskid Niski Mts and the Carpathian Foothills.

A high variability ofthe dates of the start and the duration of seasons was observed. The trends of durationand starting dates are multidirectional. The longest season is summer (89 days), which starts increasingly earlier and lasts increasingly longer. An increase in duration also refers to pre-spring and autumn. Increasingly shorter winters and springs were also observed within the multi-year period

The object of this study was the actual inflow of short-wave solar radiation (K↓) to the plateau and the bottom of a canyon in the southern part of the Kraków-CzęstochowaUpland. Its diurnal and annual variability was expressed in hourly, daily, monthly, seasonal and annual K↓totals from the years 2008–2014. The K↓flux was measured using CM3 (305–2800 nm) sensors. Great diversity of the terrain, varied landforms, expositions and slopes, big denivelations, and also the diversity of land cover and land use makes this small area very diversified as far as radiation conditions are concerned. On the basis of the actinometrical study the differences in radiation were assessed on two different landforms: plateau and the bottom of a canyon. The mean daily value of the total K↓ in the analysed period amounted to 10.8 MJ·m^–2 on the plateau and 9.1 MJ·m^–2 at the bottom of the canyon. The mean annual total K↓, in he studied multi-year period amounted to 3955 MJ·m^–2 and 3312 MJ·m^–2 , respectively.

The aim of this study was to determine the number of hot days, very hot days and very frosty days as well as heat waves and cold spells in the Świętokrzyskie Mts ( central Poland ) during the 1981 – 2013 period. Datasets of minimum and maximum daily air temperatures from the IMGW-PIB stations : Kielce-Suków, Bodzentyn and Święty Krzyż were used in the study. During the last 35 years 17 heat waves and 12 cold spells occurred in the study area. The number of hot and very hot days and heat waves on the summits of the Świętokrzyskie Mts ( Święty Krzyż weather station ) was 2 – 5 times lower than at the valley stations. There was an evident increase in the occurrence frequency of hot weather extremes in the 2001 – 2010 period as compared to the end of the past century. There is no clear tendency to change in the number of very frosty days and cold spells. Two indices : WSNC and WSNZ were proposed as tools for the assessment of the intensity of heat waves and cold spells.

The aim of the article is to analyze methods of flood risk assessment used in Poland and to compare the results obtained on the basis of these analyses. The analysis involves 21 communes (Polish: gmina), which in the document created by the Department of Security and Crisis Management of the Łódź Municipal Government were referred to as those in which the damage connected with flooding is the biggest. In accordance with the Flood Directive (2007), flood risk is a “combination of the probability of a flood event and potential adverse consequences for human health, the natural environment, and culturaland economic activity” (Flood Directive of 2007, Art. 2 Item 2). The article uses the methodology implemented in the Flood Control Operating Plan for the Łódź province (2013), Plans of Flood Risk Management (2015), and their results were compared with the author’s interpretation. Research has shown that the biggest discrepancies concerning flood risk levels concern five communes: Uniejów, Działoszyn, Warta, Gidle and Sulejów. This is linked with a different attitude towards flood risk. Regrettably, there still exists no reliable method of risk assessment, which would greatly facilitate the pursuance of an adequate anti-flood policy.

The main object of this paper was an analysis of the causes and effects of the disintegration of urban-rural conglomerates (urban communes with a dual, urban and rural spatial character). In the years 2008-16 4 urban communes changed their status into urban-rural (Szczawnica in 2008, Czarna Woda in 2014, Władysławowo in 2015 and Pieszyce in 2016), which involved a secession of 15 rural administrative units. In the justifications of the Council of Ministers regulations financial benefits and functional, structural-spatial and social factors were indicated as the reasons for, that the changes in the status of communes. In the nearest years secession tendencies are most probable in the case of towns divided into rural administrative units and towns containing separate settlements of a rural character (former villages). Secession of rural administrative units in the case of urban communes can be formally conducted in three ways: changing the commune status from urban to urban-rural, dividing the urban commune into two communes (urban and rural) and through the incorporation of rural administrative units functioning in city borders into existing rural communes.

This article presents the origins and the impact of demographic and socio-economic factors on the process of demographic ageing of the population of Cuba. The main aim of the study was to show the dynamics and regional differences in population ageing based on the W_SD dynamic ageing index_, as well as the W_SE economic ageing index.It was shown that the ageing process reveals moderate diversity of the investigated phenomenon both in the urban-rural dimension as well as at the regional level. The process of population ageing is progressing throughout the whole country and its fastest pace was recorded in the outermost provinces.However, spatial differences in the ageing process may change fundamentally in the years to come, which will result from internal regulations concerning the mobility of the population, and new business investments. As a result, spatial differences are likely to increase and the spatial image of the ageing processwill probably change.