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The wonderfully named Little Piddle is a small chalk stream that flows through the central valley of Lyscombe nature reserve. After percolating through the chalk bedrock of the surrounding landscape, water emerges from the ground from several springs and seepages at the edge of a small wet woodland. From here, it flows south, overtopping a medieval fish-hatch and passing by Lyscombe Chapel, before continuing underneath an old farmyard and then along the valley through improved grassland, before being directed into a culvert pipe and underneath Drakes Lane, where it leaves the reserve. The stream joins the River Piddle just before Puddletown, with the water eventually entering Poole Harbour.

Like the overwhelming majority of watercourses in the UK, the Little Piddle has been modified to suit agriculture: straightened, culverted, and separated from its floodplain. These changes have drained the wetlands, reduced biodiversity, and allowed nutrients such as nitrogen and phosphorus to flow unchecked downstream.  

Once in Poole Harbour, these pollutants feed algal blooms that choke seagrass meadows, deplete oxygen, and threaten rare species such as avocets, spoonbills, and black-tailed godwits. At Lyscombe, these changes have meant the river is no longer able to function as it used to naturally. The very name ‘Lyscombe’ is an indication of the valley’s much wetter past. It is thought that the name refers to ‘a valley (coombe) where reeds (lisc) grow’¹, which suggests the valley was once much wetter, with reeds, sedges, and other specialist wetland plants providing diverse habitats for a whole host of species. Dragonflies, amphibians, water voles, and wading birds would have thrived here. With the water now focused into a single uniform channel and disconnected from the floodplain, we have lost these precious wetland habitats.

To improve the ecological and hydrological health of the Little Piddle, we plan to reconnect the stream to its floodplain and allow the water to take a more natural course. Using guidance from a hydrological survey we commissioned when we acquired Lyscombe, we have identified several ways in which we can restore the natural hydrological processes across the reserve.

One of the areas where we have already made some significant progress is at the former farmyard. In the past, the stream here was controlled by a metal sluice gate before passing through an archway underneath an old flint wall and then being confined into a culvert pipe buried beneath the concrete yard. Whilst the flint wall must remain as it is a historic feature, the metal sluice gate, culvert pipe, and concrete yard have now been removed, freeing the stream from its concrete confines. Where the concrete yard once was, we will be sowing wildflower seeds, so in the future there will be a species-rich meadow leading down to the stream. Further work to reconnect the Little Piddle to its floodplain is planned for this coming winter with the installation of several leaky dams.

Leaky dams have been shown to be incredibly effective at our Wild Woodbury nature reserve and would once have been commonplace on waterways across the country. Industrious beavers construct dams to hold back water and create incredibly biodiverse wetland habitats. In the absence of any beavers at Lyscombe, we will be doing our best to emulate these ecosystem engineers, aiming to hold enough water back so it spills out of its man-made channel, creating a wider and more complex stream with several braided channels and a wetland habitat that is more resilient to drought and provides many more opportunities for wildlife to flourish.

The benefits of this work will not be limited to Lyscombe. More water being held on site and being released slowly helps reduce the likelihood of flash flooding downstream. With water moving slower through the reserve, nutrients are able to be held in the soil and vegetation, meaning cleaner water will leave the reserve, ultimately strengthening Poole Harbour’s resilience and helping seagrass, shellfish, and birds recover.

At Lyscombe and beyond, Dorset Wildlife Trust is demonstrating how restoring rivers to their natural course can heal whole landscapes — from chalk valleys to coastal harbours.  

¹ Key to English Place Names (KEPA), Institute for name studies, University of Nottingham