Bioscience Evidence 2024, Vol.14, No.4, 172-183 http://bioscipublisher.com/index.php/be 175 Research has shown that beaver dams can endure flow volumes of up to 1.34 m³/s per meter width for a 1.4 m high dam, demonstrating their remarkable engineering capabilities (Müller and Mcfadzean, 2019). The construction process involves the strategic placement of branches and logs to form a sturdy framework, which is then reinforced with mud and stones to enhance stability and water retention (Müller and Mcfadzean, 2019). 4.2 Types and structures of dams and lodges Beaver dams and lodges exhibit considerable variation in their structure and form, influenced by the landscape setting and available materials. Dams can range from simple, low-head structures to complex, multi-tiered systems that span wide river channels. The physical structure of dams can significantly alter the dynamics of pond storage and water flow, with different dam attributes such as height and length being influenced by the materials used and the water source (Rønnquist and Westbrook, 2021). Lodges, on the other hand, are typically constructed within the ponds created by dams and serve as the primary living quarters for beaver families. These lodges are built with similar materials and techniques, providing a secure and insulated habitat (Müller and Mcfadzean, 2019; Rønnquist and Westbrook, 2021). 4.3 The role of beaver dams in water management Beaver dams play a crucial role in water management by altering hydrological regimes and enhancing ecosystem resilience. The construction of dams impounds water, increasing surface and subsurface water storage, which can mitigate the effects of drought and reduce flood risks (Larsen et al., 2021; Puttock et al., 2021). By creating ponds and wetlands, beaver dams enhance groundwater retention, reduce stream gradient, and trap sediments, thereby improving water quality and promoting biodiversity (Müller and Mcfadzean, 2019; Brazier et al., 2020). Additionally, beaver dams can attenuate peak flows during storm events, reducing the risk of downstream flooding and contributing to natural flood management (Puttock et al., 2021). The ability of beaver dams to modify hydrological and geomorphological processes underscores their importance as natural water management tools in both contemporary and rewilding landscapes (Larsen et al., 2021; Puttock et al., 2021). 5 Hydrological Impacts 5.1 Alteration of water flow and storage Beavers are renowned for their ability to alter water flow and storage through the construction of dams. These structures impound water, creating ponds and wetlands that significantly increase surface and subsurface water storage. This alteration in water storage is a primary driver of the hydrological changes observed in beaver-impacted areas. For instance, beaver dams can modify the reach-scale partitioning of water budgets, allowing for site-specific flood attenuation and altering low flow hydrology (Figure 2) (Larsen et al., 2021). The physical structure of beaver dams, including their height and material composition, plays a crucial role in determining the dynamics of pond storage and the overall hydrological impact (Rønnquist and Westbrook, 2021). Additionally, beaver dams can increase evaporation rates and water residence times, further influencing the local hydrological cycle (Larsen et al., 2021). 5.2 Effects on groundwater recharge and surface water dynamics Beaver dams have a profound impact on groundwater recharge and surface water dynamics. By creating ponds and wetlands, beaver dams enhance the connectivity between surface water and groundwater systems. This increased connectivity facilitates groundwater recharge, particularly during high flow events, and can lead to flow reversals where water moves from the stream to the floodplain (Pearce et al., 2021). The presence of beaver dams also reduces the groundwater-to-stream hydraulic gradient, promoting a more stable and sustained groundwater flow into streams (Pearce et al., 2021). Furthermore, the alteration of surface water dynamics by beaver dams can lead to increased vertical hydraulic exchange gradients and expanded anaerobic conditions, which have significant implications for biogeochemical cycling and nutrient dynamics (Larsen et al., 2021). 5.3 Impact on flood mitigation and drought resilience Beaver dams play a critical role in natural flood management and enhancing drought resilience. The construction of beaver dams attenuates flow, reducing peak flows during storm events and increasing the lag time between
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