It has been confirmed many times in human history that what is currently considered waste can be a source of solutions to problems. Such a story was, for example, the accidental discovery of penicillin by the Scottish scientist Alexander Fleming in 1928. Similarly, the knowledge of the impact of water on climate is also accidental. This arose as a by-product of a solution to obtain water resources by ecosystem-based rainwater retention, in order to improve the yield of water resources so that the springs could produce enough water for use even when it is not raining.
For this reason, experimental research was developed in the Kysuca river basin, where the scientific research project DALIA (Danube Lighthouses for Innovative Action in the Danube Basin, www.dalia-danube.eu) monitors the impact of nature-based solutions (NBS) on ecosystem-based rainwater retention, on the restoration of already dried-up springs and on the improvement of minimum flows in economically exploited land.
A number of discussions at the DALIA consortium meetings led us to seek answers to the questions posed, whether this knowledge could be reflected in a comprehensive model of the country’s resilience to floods and droughts, improving the yield of water resources in the country, protecting biodiversity, improving soil fertility in the agro-forestry landscape and, last but not least, slowing down the overheating and cooling of the country, or cooling heat islands.
Long discussions in the team finally led us to consider using rainwater, which during times of intense rain is considered waste and therefore we channel it out of the country without benefit. Rainwater flows away without benefit and brings flood risks in the country. The idea was how to involve ecosystems in the damaged country, which suffers from a lack of water, in order to bring benefits to the forest, agricultural and urbanized country.
These discussions finally brought about the surprising realization that if all the rainwater that is wasted in the damaged landscape, which is a burden on the landscape during times of intense rains, were to be left in the ecosystem, it would participate in improving the water resources in the basins, increasing the fertility of the landscape, cooling the landscape, and even increasing the consumption of CO2 from the atmosphere as a source of fertilizer for the landscape.
Of course, this thesis can reliably be valid provided that ecosystems have an increased water retention capacity so that part of the retained rainwater replenishes the soil water reserves and evaporates and cools the air through plants, like an air conditioning device. The part of the water that seeps into the subsoil by gravity will replenish the groundwater reserves and will participate in the renewal of springs.
Therefore, we had to find answers to the systemic response to:
1. What is the potential for rainwater use and how can it be used in the context of real solutions and economic real demands
2. How to calculate the volume of water retention measures in the landscape, where to place them in the landscape and what technologies to use for this in different types of landscape
3. What scale is appropriate to use for preparing plans to increase retention capacity for analysis and implementation of solutions in the landscape
4. What benefits can be expected from improving the retention capacity of the area after investing in
a. Water resources
b. agricultural soil fertility
c. improving the forest economy
d. temperature regime of the landscape
e. CO2 consumption
To calculate the potential for rainwater use, we used the CN curve method, which reliably reflects the real volume of rainwater runoff from small drainage areas for extreme precipitation, which forms surface runoff. Since we only have interim results from research in the Kysuca River basin, we chose to calculate the volume of runoff for an intense rainfall with a probability of occurrence once a year (60 mm). After obtaining knowledge from monitoring, the nature of the rain and its periodicity of occurrence can be further realized, including the realization of the economic cost of investments. This can be the subject of subsequent research.
The second problem we needed to deal with was what scale of the proposed measures in the landscape structure to use. Since this is a calculation of rainwater runoff from small areas, we used the basic characteristics (soil, climate, relief) and the way of land use (forests, agricultural and urbanized land, transport infrastructure) at the level of the municipal cadastre. For various landscape structures, we subsequently obtained the volumes of rainwater runoff for a rainfall with a probability of occurrence once a year. We made these calculations for each cadastre. This resulted in solutions that are part of the proposal for the implemented NbS measures for each community and subsequently for the entire basin. Thus, each community has its own plan, how much needs to be done and in more detail with different technological solutions for the type of landscape and its use.
Although the preliminary results do not allow us to quantify how frequently the proposed solutions for the volume of one-year precipitation will be involved in the ecosystem retention of rainwater (we will be able to evaluate this after obtaining knowledge from further monitoring), but based on the knowledge gained about the nature