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How your garden affects the local water table

Lusaka, the capital city of Zambia, is known for its hot and dry weather conditions. Historically, we regularly experience flooding within the city during the rainy season. Fortunately, some of this sinks down to the water table which is an underground water reservoir that develops in certain areas.

In contrast, the dry season the city becomes very dry and extremely dusty as vegetation dies back. The water table slowly sinks lower and underground water becomes harder to reach. Many residents and businesses rely on boreholes for their water supply, but it's not uncommon for these boreholes to dry up, leaving households with limited or erratic access to water.

High demand for water:

It's obvious that during the dry season, the demand for water increases as more people use boreholes for their daily needs. However, there is increased demand after the rains as people now use this water to sustain the plants in their garden or fields. The increasing number of boreholes and water consumption is depleting the water supply before it can be replenished at the end of the year.

As a gardener we need to be very conscious of how much water we use as one of the principles of sustainable gardening is to not put more pressure on our natural resources than is necessary.

How can you help

It is also important to remember that the underground water is not infinite but it is a shared resource. The more water you use, the less that is available for other people.

Most lawns need the equivalent of 10-40 litres of water per meter squared (keeping in mind, that in can vary depending on type of soil, seed etc.).

Climate change:

Climate change is another factor that can contribute to boreholes drying up in Lusaka during the dry season. With rising temperatures and changing weather patterns, it's possible that we may not be receiving as much rainfall as we used to.

However, we still need to maintain water catchment areas, places where the water can slow down enough to sink into the ground and unfortunately, as we develop the surrounding areas around the city we lose more of these wetland areas that feed the underground water system.

How can you help

Trees and other plant roots help slow down the water as it flows to lower areas. The more surface area that we have that is planted up with grass or trees or other plants, allows for more seepage of water into the ground. As a gardener, you can choose to minimise the amount of space around your house that is paved or covered with cement. Planting in these areas will allow water slow down enough not to sink into the ground.

Leaching of Nutrients and Chemicals:

If you consistently overwater your garden or fields, the excess water can wash away nutrients and chemicals from the soil. These nutrients, including nitrogen and phosphorus from fertilizers, can be carried down into the soil layers and eventually reach the groundwater. While this might not directly lower the water table, it can contribute to groundwater contamination and alter its quality.

Needless to say, an excess of unnecessary chemicals in our drinking water can have negative effects on our food crops and on our health.

How can you help

There are many organic or natural fertilisers and sprays that can be used in your garden to minimise on the use of chemical additives.

Boreholes drying up in Lusaka during the dry season can have significant impacts on communities and businesses that rely on them for their water supply. As a community we do need to implement sustainable water management practices and invest in proper maintenance and infrastructure.

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