Bóbr - przyjaciel czy wróg? Naturalna mała retencja odpowiedzią na niekorzystny bilans wodny Polski

摘要: Growth of demographic and urbanization expansion from XIX century is a cause for shrinking water resources over the world. A remedy this problem since 1950s retention - 40 thousands dam reservoirs, with dams higher than 15 meters, were build during last century. Several decades operating such reservoirs show that not always they are beneficial economy nature. Their negative influence on riverine ecosystems reason liquidating big tendency observed in decades. An alternative effects searching solutions, which providing does interfere biological processes within body. Such modern approach to retention, compliant sustainable development, particularly important Poland due growing deficit resources. This deficiency only associated natural conditions Poland, but also long lasting negligence saving resource, so called "small retention". analysis literature shows way storage environment using behavior beavers ponds. It appears building dams, help have positive their surroundings. beaver-made ponds many aspects, both hydrological biological. However most is, contrary artificial ponds, ones built by degrade river course downstream. On other side, damming stimulates rivers. The effect very significant. estimated be between 10 20 millions cubic meters countrywide same amount as generated all programs small working Poland. Also economic factor beaver mediated almost generate any costs. Yearly costs financial compensation paid some damage caused do overcome few hundred thousand zlotys. News emerging after bigger floods blaming damaging dikes has mostly medial character usually just detract responsibility local authorities maintaining anti-flood systems.