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Fortunes Matutu
IN many parts of the country deforestation, land degradation, and overgrazing have adversely affected the land’s ability to absorb rainwater, causing 60 to 70 percent to be lost as runoff, silting dams, and turning fertile farmland into “deserts”.

In yester-years, water flowed year-round in many rivers and streams but now they are dry or filled with sand and mud.

Dam levels across the country have risen in response to the recent rainfall activity, the national average being 85,7 percent.

Nevertheless, this is not the case with every water body as some have not received significant amounts of water.

It has been noted dams supplying Bulawayo have increasingly failed to record significant inflows even during a good rainy season.

According to Zimbabwe National Water Authority February 2022 statistics, dams supplying Bulawayo are well below the national average and have recorded less inflows.

Upper Ncema was 23 percent full, Lower Ncema 84 percent, Inyakuni 51 percent, and Mzingwane nine percent.

Poor inflow affects water supply, livelihood activities and leads to excessive water shedding.

Poor water inflows can be caused by several factors, but one of the main causes is environmental degradation in watershed areas.

A watershed is a land area that drains or channels rainwater and streams to a common point, such as a reservoir, dam, river, or wetland.

Watershed areas need to be conserved and maintained in their pristine state to ensure water security to support livelihoods and biodiversity.

Vegetation, soil, and wetlands must be maintained to ensure the availability and inflow of clean water.

The ecological significance of trees and forests can be seen in their beneficial effects on water catchment areas, where they regulate stream flows and protect soils from erosion and siltation.

Trees serve as natural sponges, collecting and filtering rainfall and releasing it slowly into streams and rivers, and are the most effective land cover for maintenance of water quality.

The strong tree roots anchor soil against erosion, reducing soil erosion which causes siltation of water bodies.

When it’s raining, trees and forests in watershed areas control storm runoff.

Their leaf canopies help reduce erosion caused by falling rain by capturing and storing rainfall in their canopies and releasing water into the atmosphere through evapotranspiration.

Trees in watershed areas help to recharge the water table by allowing water to enter the ground.

Roots take up water and together with dead leaves create conditions that promote soil infiltration.

The presence of trees and organic matter protects the soil from the impact of raindrops by binding soil to their roots and transpiring large amounts of water.

Furthermore, organic matter also enhances the soil’s water-holding capacity, thereby reducing runoff.

Wetlands play an important role in the ecology of the watershed.

Their function is similar to a sponge which traps and slowly releases surface water, rainwater, groundwater and floodwaters.

As sediment, excess nutrients, and chemicals flow off the land, wetlands filter the runoff before it reaches the open water, thus improving water quality and controlling soil erosion.

Most wetlands are located on floodplains with the capacity to temporarily store floodwaters during high runoff events hence contributing to disaster risk reduction.

Wetlands can reduce the severity of downstream flooding and erosion by holding back some of the floodwaters and slowing the rate that water re-enters the stream channel.

Forests and wetlands around the world are, however, severely threatened.

Zimbabwe has lost over 85 percent of the wetland areas and deforestation is occurring at an alarming rate of 262 349 ha per year.

Of the existing wetlands, approximately 61 percent of Zimbabwe’s wetlands are moderately degraded, and the country will likely lose all its natural water reservoirs by 2040.

The degradation of watersheds affects many natural ecological processes important to the protection of water resources.

This contributes to the loss of access to clean water, pollution of water sources, and a reduction in the carrying capacity of water bodies.

Without trees and riparian vegetation, watersheds are prone to soil erosion and silted reservoirs, polluted water and shortages of potable water.

The main causes of deforestation in watershed areas in Zimbabwe are settlement and agriculture expansion, logging for construction materials, firewood extraction, veld fires, brick moulding, overgrazing and mining activities.

In mining areas, extensive areas of land and vegetation have been cleared to enable gold sensors to detect gold and make way for alluvial mining activities.

Illegal alluvial miners thrive along the watershed area where they carry our gold panning in rivers and waters ways depositing huge volumes of soil.

Several underground mines actively work to reduce the water table or divert major waterways away from the mines.

Especially in areas with high mining activity, this exercise can affect surface and groundwater quality and availability.

Stream-bank cultivation is a leading cause of watershed degradation.

It involves cultivating within 30 metres from the highest flood level of the water body.

Through stream-bank cultivation, the soil is loosened and ground cover is lost, resulting in soil erosion, siltation, and runoff. Consequently, waterbodies hold less water for a very short period.

In the dry season, people and livestock suffer from a lack of water, and boreholes fail to function due to a lack of charge.

Land-use changes, improper farming practices, and overgrazing further impair water availability by magnifying the effects of degraded watersheds.

We need to protect the natural resources in our watershed to preserve the health and well-being of all living things.

A healthy watershed protects water supplies, nurtures forests, plants, and wildlife, keeps the soil fertile, and supports self-reliant communities.

Forests and trees must be recognised as prime regulators within the water, energy and carbon cycles for the benefit of all economic sectors.

If these functions are ignored, planners will be unable to assess, adapt to or mitigate the impacts of changing land cover and climate change.

Good planning is needed to protect forest cover, preserve wetlands and control land degradation.

Despite this, environmental components in projects, including watershed management, often get a low priority because many environmental benefits are difficult to measure and the “tragedy of the commons.”

-Fortunes Matutu is an ecologist and a forester with the Forestry Commission who has a special interest in social forestry.