In Tuala area in Kajiado County, south of Nairobi, a small unintentional lake with suspended sediment load in an abandoned quarry has been a source of concern for residents and environmentalists. In Narok County, west of Nairobi, storm water is said to be stripping farms of soil.

These are some of the effects of landscape alterations due to the construction and operation of the standard gauge railway (SGR), scientists say, adding habitat destruction and impeding wildlife movements to the list.

In fact, scientists are questioning how effectively recommendations from environmental and social impact assessment (ESIA) proposals for the SGR were implemented in the development of the railway seeing as there is widespread environmental degradation around SGR.

“Our research and anecdotal reports point to the existence of negative impacts on the ecological wellbeing and processes along the SGR corridor,” said environmentalists in a report titled Assessing the ecological impacts of transportation infrastructure development: A reconnaissance study of the Standard Gauge Railway in Kenya released in February.

The China-funded and constructed SGR project was given the go-ahead following the completion of two environmental and social impact assessments, but scientists question how effectively recommendations were implemented in the development, given the widespread environmental degradation.

“Large-scale infrastructure investment are a catalyst for economic growth, but our research shows that before this can happen more work is needed to quantify ecological impacts on the land,” observed Prof Robert Marchant, from the University of York's Department of Environment and Geography.

“Not only this, but should issues arises once the projects are complete, there must be a ready-to-go mitigation strategy that can be applied to reduce further damage quickly.”

Now, they are asking project managers to develop sustainable and ecologically sensitive measures to mitigate the key ecosystem impacts.

Value erosion

“It’s not yet clear what ecosystem services could be lost in the longer term, clearly the infrastructure impacts on ecosystems will affect the value and delivery of natural capital, particularly those associated with water and wildlife impacts,” said the scientists.

The SGR construction was accompanied by activities such as soil compaction, excavation and movement of soil from one location to another to erect the embankments.

These activities altered and created barriers to natural processes including natural hydrology and animal migration routes.

The research published in the PlosOne journal, said the main environmental impact observed from the SGR is ecosystem degradation.

“Construction of the SGR together with the associated quarrying activities resulted in removal of forest or vegetation cover, destruction of water sources such as rivers, wetlands, grasslands, and parts of protected areas.

‘‘Respondents observed that activities along the SGR, modified or disturbed the natural ecosystems especially low-lying, poorly drained land in areas around Kibwezi, Mombasa and Voi,” researchers noted.

“Our team observed that wetlands around Kitengela and Kiboko were blocked off and damaged, thereby affecting natural water flow. Similarly, we observed that forests in Kibwezi at the KEFRI station had been cleared to create way for the construction of the railway.”

According to the team, there was emergence of illegal activities such as grazing in protected areas.

“Kenya Wildlife Service officials observed that “local communities use the underpasses to pass their livestock through to Tsavo National Park particularly around Bachuma Gate”.

The livestock incursions they observed “resulted in serious soil degradation in the southern part of Tsavo East”.

Local communities around quarries used for construction materials reported impacts of “blasting for construction materials causing tremors in the area, leading to buildings cracking,” for example, at Oloosirkon Primary School. Meanwhile, dust pollution was also a challenge and impacts include infections from dust, coughs and chest pain”

At the coast, Community Forest Association officials reported increased sediments eroded from the railway embankments that not only affected mangroves seed development and self-germination but also blocked streams in Kilindini.

In Voi, county officials observed that “storm water directed to the culverts flooded low lying homesteads and farms during heavy rainfall”.

It also emerged of recent invasive plant species spreading rapidly along the SGR corridor. The problem is being observed both in Tsavo East-West National Parks, where the invasive cactus Opuntia stricta and Prosopis juliflora (known locally as Mathenge) were also prevalent along the new highway from Voi to Taveta.

Invasions and siltation

However, we could not establish the connection between the spread of invasive plant species and construction and operation of the SGR,” said the scientists.

Additionally, respondents from Nairobi and Narok Counties reported incidents of “flooding along the culvert [underpasses] when it rained while rivers [Empakashe and Mbagathi] were blocked or dried up because they had been filled with silt from construction”.

In Narok county farmers complained directing water to the underpasses led to gulley erosion affecting soil cover. The soil has also been reported to lead to siltation of Lake Magadi.

The SGR traversed key ecosystems and resources creating a barrier to the movement of terrestrial animals and reducing sizes of some ecosystems and resources. Participants in the meetings raised concerns that “the infrastructure had been seen to affect wildlife movement, for example with animals congregating along the highway”.

Other issues raised include loss of ecosystem integrity through truncation of ecosystems into smaller, often isolated, patches that may not maintain or sustain ecological processes in the long run. Also of concern was physical disturbance and disruption to the composition, structure and functioning of ecosystem.

Movement, migration and survival of wildlife species, deaths through vehicle/train–wildlife collisions and behavioural modification among diverse species were major issues.