## 2 Materials and Methods
### Characteristics of the Study Area
7.4-7.5 \({}^{\circ}\)C, annual precipitation typically ranges from 600 to 650 mm, and the annual average sunshine time ranges from 1550 to 1600 h. The RNP is characterised by a high topoclimatic diversity due to its varied topography. Large differences in elevation and sun exposure lead to differences in plant species composition, and consequently, to the density and height of the vegetation cover [28]. The surface water network in the RPN area is very sparse and covers only 52.6 hectares, which is only 0.62% of the total park area. This situation is mainly due to the high perme  
Figure 2: Geological structure of the River Swierszcz catchment. Own elaboration based on [26]. ability of the bedrock and its water-holding capacity, which has the effect of retaining water from precipitation. In turn, groundwater is found in porous fractured marls, opokas and gazies of the Upper Cretaceous, as well as in sandy sediments and Quaternary gravels, which fill buried river valleys. The waters of the Cretaceous layers mix with the waters filling the alluvialia in the river valleys. The whole forms a circulation-and-drainage system called the Roztocze Water Level, which has large reserves of groundwater [29]. The flow of the River Swierszcz is variable and depends on the climatic and terrain conditions. In the recent hydrological years, variable river flows were recorded in the \"Malowany most\" (\"Painted bridge\") profile (P3), which closes the 18.15 km\({}^{2}\) catchment area of the River Swierszcz. Reports from the \"Roztocze\" Base Station of the IMNE (BS IMNE) show that the highest flows were recorded in 2013 at an average level of 0.95 m\({}^{3}\)/s. The maximum daily flow then was 0.575 m\({}^{3}\)/s, and the minimum one was 0.056 m\({}^{3}\)/s. The lowest flows were registered in the hydrological year 2019/2020, when, after a series of dry and hot years, the supply of the stream with deep waters of the Cretaceous level clearly decreased. The average annual flow was only 0.007 m\({}^{3}\)/s, with a maximum of 0.030 m\({}^{3}\)/s and a minimum, similar to the year 2019, below 0.002 m\({}^{3}\)/s. All villages in the catchment of the River Swierszcz are connected to a mains water supply network, with the exception of the settlements of Florianka and Lasowe, which are both located in a forest. The Florianka settlement where The Animal Breeding Center is located has its own water intake and water supply system. Wastewater is discharged to a hybrid constructed wetland [30]. The sanitation coverage level of the villages of the catchment area of the River Swierszcz is low. The town of Zwierzynicc and the village of Sochy have their own sewage systems. Some households are fitted with domestic wastewater treatment plants. However, most households discharge wastewater into septic tanks. The ongoing climate change and the increasing demand for water lead, among other issues, to the lowering of the groundwater level and a decrease in well efficiency. This phenomenon was observed in Florianka, which is a unique settlement on the map of the RNP. Florianka is home to the Animal Breeding Center devoted to the conservation of the Polish konik horse, which is the official symbol of the park, and primitive cattle and sheep breeds: white-back cows, red cows and Uhruska sheep. There is also a field base for educational and tourist activities called Izba Lesna (Forest Room). Approx. 35,000 tourists visit this place every year. In the lower section of the River Swierszcz, there is a \"sanctuary\" of the Polish konik horse. A herd of up to 25 horses lives here throughout the year, grazing in an area of approx. 260 ha. One of the measures that can be taken to counteract the effects of climate change is rainwater harvesting and use, which can secure access to fresh water. The idea of the RWHS, taking into account various ways of using rainwater, is schematically presented in Figure 3. Some of the applications require the maintenance of appropriate water quality.