Nitrogen and phosphorus budgeting is considered to be a key tool for policy makers and stakeholders when dealing with nutrient contamination issues, however no unified method has been employed in countries affected by this eutrophication problem. The current study offers a detailed insight into the estimations of nutrient loads and their distribution between different sources for a middle-sized agricultural catchment, with the use of two approaches: mass balance (static) and modelling (dynamic). Both methods revealed similar contributions of analysed nutrient sources, although the final estimates in the chosen calculation profile were divergent due to the various reasons related to the methods’ specificity. The advantages and disadvantages of both approaches have been specified in our study, and a hybrid solution on a local and country wide scale has been proposed.

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The issue of whether land use changes will balance out sediment yields induced by climate predictions was assessed for a Carpathian basin (Raba River, Poland). This discussion was based on the Macromodel DNS (Discharge–Nutrient–Sea)/SWAT (Soil and Water Assessment Tool) results for the RCP 4.5 and RCP 8.5 scenarios and LU predictions. To track sediment yield responses on the sub-basin level the studied area was divided into 36 units. The response of individual sub-basins to climate scenarios created a mosaic of negative and positive sediment yield changes in comparison to the baseline scenario. Then, overlapped forest and agricultural areas change indicated those sub-basins where sediment yields could be balanced out or not. The model revealed that sediment yields could be altered even by 49% in the selected upper sub-basins during the spring-summer months, while for the lower sub-basins the predicted changes will be less effective (3% on average). Moreover, the winter period, which needs to be re-defined due to an exceptional occurrence of frost and snow cover protecting soils against erosion, will significantly alter the soil particle transfer among the seasons. Finally, it has been shown that modeling of sediment transport, based on averaged meteorological values and LU changes, can lead to significant errors.

Purpose This study analyzes the variability of sediment loads under variant climate change and land use scenarios in a Carpathian catchment with a dam reservoir. The areas with the highest share of sediment loads are tracked to establish possible indications for future catchment management plans. Materials and methods Analyses were performed for the Raba River catchment (Poland, Carpathian Mountains) with use of the Macromodel DNS/SWAT. The RCP 4.5 climate forecast predictions (2021-2050 and 2071-2100), downscaled for the area of Poland, and land use predictions from the DYNA-Clue model for the Carpathian area, were taken into consideration. A total of seven scenarios were created, accounting for precipitation (P1 and P2), temperature (T1 and T2), land use (LU) changes, and combined effects (COMB1 and COMB2).Results and discussion The average load delivered to the dam reservoir was estimated as 2.43 Gg y −1 , and its seasonal/yearly variability was followed by local meteorological phenomena. Among the tested factors, precipitation change, in terms of total amount and intensity, exerted the most impact on sediment loads causing their increase. Temperature and land use changes resulted in a slight decrease. Combined scenarios implied that changes of the catchment area use, such as increase of forest cover, can noticeably reduce sediment loads delivered into a dam reservoir. Conclusions The performed simulations revealed the importance of incorporating variant scenarios for catchment management plans, development of land use mitigation measures (erosion), and operational procedures for the dam reservoir. Particular attention should be paid to warmer winters with heavy rainfalls and temperatures above zero, which together with a lack of plant vegetation result in elevated annual sediment loads reaching the dam reservoir. Further changes must be mitigated by anti-erosion investments.

Abstract. On Earth water is an irreplaceable asset, and an estimate of its resource capacity is necessary. The improper selection of indicators of water resources can lead to the underestimation or overestimation of the actual resources present. Incorrect assessments of water resources contribute to the improper completion of necessary water management tasks, thereby failing to satisfy the needs of different water users such as industry, agriculture and forestry, inland water navigation, tourism and recreation and the general population for the purposes of municipal water use. This article discusses the advantages of utilizing Earth Observation technology for estimating water resources in Poland. Despite the large amount of water on Earth, decades of wrongly pursued water management have led to a critical point in maintaining this valuable resource. According to actual estimations, there are enough fresh water resources in the world; the problem is the uneven distribution and pollution of these resources, especially in the case of surface water. Currently, Poland, in comparison with other European countries, is classified as a country with very little water resources. It is important, however, that a thorough evaluation using the latest measurement technologies is conducted, particularly for groundwater resources in deep layers of the lithosphere. The proper assessment of water resources requires knowledge of the hydrogeological conditions within each of the catchments of the analyzed area. International data sets are mostly incomplete and heterogeneous, which makes the comparison of data of several years difficult and often leads to mistakes. While analyzing Polish water resources several factors should be taken into account, including: the amount of rainfall, the amount of water in rivers, lakes and groundwater, and the above-mentioned factors affecting the measurement of the amount of disposable water resources. This article is an introduction to the broader analysis of water resources in Poland and an exploration of the issue from a different perspective.