The purpose of the paper is to analyze the spatial variability of precipitation in Poland in the years 1981–2010. The average annual rainfall was 607 mm. Precipitation in Poland is characterized by high spatial and temporal variability. The lowest annual precipitation was recorded in the central part of the country, where they equaled 500 mm. The highest annual precipitation totals were determined in the south, equaling 970 mm. The average precipitation in the summer half-year is 382 mm (63% of the annual total). On the basis of data from 53 climate stations, maps were made of the spatial distribution of precipitation for the period of the year and winter and summer half-year. The kriging method was used to map rainfall distribution in Poland. In the case study, cross-validation was used to compare the prediction performances of three periods. Kriging, with exponential type of semivariogram, gave the best performance in the statistical sense. Their application is justices especially in areas where landform is very complex. In accordance with the assumptions, the mean prediction error (ME), mean standardized prediction error (MSE), and root mean-square standardized prediction error (RMSSE) values are approximately zero, and root-mean-square prediction error (RMSE) and average standard error (ASE) reach values well below 100.
The work presents the results of research on erosion and landform changes of a bottom of a dry erosive-accumulation valley in Elizówka in 1958, 1970 and 2016. The changes have been examined with the use of geodetic topographic surveys techniques. The research field was a 480-metres long part of the valley bottom. The topographic surveys in 1958 and 1970 were conducted with longitudinal (parallel to the bottom of the valley) and cross (every 20 metres) sections method. In 2016 the modern measuring devices were used. All the results, together with coordinates of points and historical data were converted into GIS spatial layer. The altitude values formed the input data for interpolation of rasters showing changes of the topography in three periods. Three TIN models were also developed to distinguish erosion and accumulation zones plus the quantity of eroded and accumulated material. The valley on the majority of its length has been raised and has changed from V-shaped into U-shaped. Accumulation of the soil material led to levelling the bottom. Accumulation concentrates along a flow line, while soil washout mainly at the bottom of slopes. The thickest sediment layers were observed in the lowest part. For the whole 1958–2016 period a total of 3470 m3 soil material has been deposited on the area of about 1.62 ha, while in the same time only 130 m3 has been eroded (from 0.22 ha).
The development of the side arm edge of the valley-gully in Gałkowice village in the Dwikozy commune (the Opatówka catchment in the Sandomierz Upland) was investigated during the period from 2002 to 2017. An increase of fragmentation of the gully edge was found. Most of the pre-existing erosive indents increased in size (maximum of 2.8 m – about 0.2 m per year). An increase in the area of the gully by 145 m2 was found. As a result, the boundary of plow tillage shifted to an average of 1.5 to 2 meters (maximum 3.8 m), which resulted in a loss of 545 m2 of adjacent arable land. As the main reason for the development of the analyzed section of the gully, meltwater flows were considered.
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