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Home The River Basin People and the River Governance Resource Management
The River Basin
Climate and Weather
Water Quality
Ecology & Biodiversity
 Aquatic Ecology
 Biodiversity in the Basin
 Eco-regions & Hotspots
 Biodiversity Resources & Protected Areas
Human Impacts
 Major Threats



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Human Impacts on Biodiversity  

Humans earn and secure their Livelihood by modification of the environment, driven by demands for water, food, and energy.

Humans intervene in aquatic habitats in three ways (Falkenmark 2003):

  1. Flow control of rivers to fit the seasonality of water flow to the seasonal water demands. Beside dams and reservoirs also well drilling and groundwater pumping manipulates water flows.
  2. Land cover changes such as cutting down vegetation (deforestation) or altered use for agricultural development.
  3. Water extraction for consumption and irrigation.

The Millennium Declaration of the United Nations aims to halve the percentage of the population suffering from poverty, hunger and lack of safe drinking water and sanitation in 1990 by 2015. To achieve these goals humans will intervene in the ecosystem with potentially negative effects on biodiversity. Falkenmark describes this as the ‘basic dilemma’:

“Humans and ecosystems share the same water.”

Because both, humans and ecosystems are fully depending on water, Integrated Water Resourses Management (IWRM) offers an approach to balance the protection of ecosystems and the demand for water to secure human livelihoods.

Logging forests for land preparation in Upper Kunene River basin.
Source: Tump 2004
( click to enlarge )

Human Impacts on Biodiversity





Overexploitation (or over harvesting) refers to harvesting a renewable source at a rate that is unsustainable

Overexploitation can effect various natural resources such as grazing pastures (overgrazing), fish stocks (over fishing), and forests (over logging)
Overexploitation harms and can destroy habitats and the species depending on this habitat
Continuous overexploitation can lead to the destruction of the resource

Alien species introduction

Alien species living outside its native distributional range, which have arrived there by human activity, either intentional or accidental

Alien invasive species often do not have natural enemies in the invaded region. They compete with indigenous species for space and nutrients and may dispossess them
Invasive species represent the second leading cause of species extinction and loss of biodiversity in aquatic environments worldwide


Pollution is the introduction of contaminants into an environment that causes instability, disorder, harm or discomfort to the ecosystem

Pollution consists of agricultural, urban, and industrial wastes containing contaminants such as sewage, fertilizer, and heavy metals
Many of the pollutants entering ecosystems are very toxic to living organisms, it has proven to be very damaging to habitats and species
They can lower reproductive success, prevent proper growth and development, and even cause death.

Habitat fragmentation and habitat destruction

Habitat fragmentation is caused when vegetation is cleared for agriculture, rural development, urbanization and the creation of hydroelectric reservoirs

Habitat degradation, fragmentation, and pollution are aspects of habitat destruction

Habitats which were once continuous become divided into separate fragments
It affects biodiversity by reduction in the dimension and amount of available habitat.
In smaller patches of habitat the competition for nutrition and space between animals increases
Migration routes may become disconnected causing problems for mobile animals to move between habitats
Adapted from US Environmental Protection Agency and various sources




Explore the sub-basins of the Kunene River

Video Interviews about the integrated and transboundary management of the Kunene River basin

Explore the interactions of living organisms in aquatic environments

Examine how the hydrologic cycle moves water through and around the earth