Managing Rainwater on Farms

The increasing intensity of rainfall due to climate change is an additional challenge for farmers to adapt to particularly as this can occur at any time during the year. Over the past 12 months, Ireland had its wettest October on record in 2022, its wettest March on record earlier this year and also its wettest July on record.

While the impacts on productivity and day to day activity are obvious, farmers need to start to consider how best to manage their farms so as the farm infrastructure can cope with this excess water and minimise the risk to water quality. This is particularly important in the farm yard and on land that is highly connected to the drainage network.

To help manage this excess water on your farm you first need to know how it flows through your farmyard or fields. The EPA have generated maps that show the flow pathways of water over land and these are a useful guide. However it is important to ‘ground truth’ these maps to ensure they are accurate. Farmers can manage their farming activities in these ‘critical source areas’ (CSAs), for example, avoid spreading slurry in the overland flow pathway area when heavy rain is forecast as this reduces the risk of the slurry being washed away.

They also show where water enters the drainage network (drains, watercourses, etc.) and this is important as farmers can then locate measures to help minimise contaminant losses to water. Establishing riparian zones and planting trees, retaining or installing wetlands, hedgerows, ponds or bunds all can help capture nutrient and sediment from reaching the watercourse.

Picture 1: Image showing overland flow pathways and measures to intercept contaminant losses

The same methodology can help in the farmyard. Rain water moves across the yard and typically is channelled to a drain that takes the water away from the yard and into the drainage network. If this water flows across soiled yard areas then this water can become contaminated with nutrients, sediment and pathogens. By spending time to assess where the water moves through the yard a farmer can then take actions to minimise the losses of contaminants.

The first thing a farmer should do is to try and reduce the volume of clean water that flows though soiled areas. Having gutters and downpipes from shed roofs in proper working order and having the water piped directly to an outfall drain is a simple and effective method of controlling clean water. However how many farms can say that these are in place?

Where water flows across the yard from clean areas then consideration should be given to installing diversions for the water to prevent it from entering soiled areas. This will help reduce the volume of contaminated soiled water that needs to be collected and land spread. Recent changes to the GAP regulations have increased the storage requirement for soiled water so spending time installing measures to reduce the volume of soiled water generated could help reduce the capacity of storage required.

On some farms located on a slope, consideration should also be given to water that enters the yard through overland flow from fields that are sloping towards the yard. Measures should be installed to intercept this water and divert it away from the yard.

Picture 2: Image showing a farm yard on a slope and the flow of water through it