Spatial Conservation planning for wind farm siting in lesotho




Дата канвертавання21.04.2016
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Spatial Conservation planning for wind farm siting in lesotho


Introduction
A number of wind farms have been proposed for the Mountain Kingdom of Lesotho, the majority of which are located on ridgelines in the high lying parts of the country. The mountainous eastern part of the country abuts the Maloti Drakensberg TransboundaryWorld Heritage Site along the border with South Africa – an area renowned for its biodiversity, cultural heritage and scenic splendour. Lesotho and the Drakensberg Escarpment are well known for theiriconic but declining population of Bearded Vulture Gypaetus barbatus (Kruger 2014) and several colonies of CapeBacked Vulture Gyps coprotheres.
One wind farm site was proposed for an area close to the edge of the northern Drakensberg Escarpment near Mont-aux-Sources. ERM was appointed to undertake an EIA of the proposed wind farm site. This paper examines the process followed to assess the site and the biodiversity sensitivities using a combination of data from vulture surveys, expert knowledge by ornithologists, and available spatial data from systematic conservation planning datasets compiled for the Maloti Drakensberg Transfrontier Project. It demonstrates the unique advantage gained from access to available spatial biodiversity data in combination with expert specialist knowledge of priority species to inform the development proposal and possible alternatives.



The Wind Farm Project

The wind farm site occupied 8000 ha located to the north of the road between Oxbow and Mokhotlong in Lesotho (see Figure 1). The windfarm was designed to generate 150MW of energy from 100 turbines of 1.5MW each. Each turbine was to be 65m in height with a rotation distance (blade tip to tip) of 77m. The wind turbines were to be placed in lines on top of and parallel with a series of ridges, with a minimum spacing of 300 m - 500 m between individual turbines. Electricity generated from the wind farm would be fed into the grid via a 132kV line to a substation 39 km away, while internal overhead lines would connect the different turbine areas. Various alternative sites had been previously screened from a technical perspective but no alternatives to the wind farm site were proposed by the developer for the EIA.
Figure 1. Location of Wind Farm Site in Lesotho



Site Setting and Biodiversity Importance
The wind farm site was located at an altitude of 3200m in the highest alpine area on the top of the Drakensberg escarpment. The remote and desolate terrain is undulating and comprises ridgelines intersected by valleys with seepage and valley head fen wetlands. The fens are a unique wetland type located at high altitudes and considered a critically endangered wetland type (SANBI 2013). They are under major threat of livestock grazing which causes erosion dongas leading to wetland drying and shrub encroachment. The steep escarpment edge with its dramatic vertical cliffs is located 2km from the proposed wind farm site. These cliffs which run for most of the 1000 km length of the escarpment and are home to a number of cliff-nesting birds, including the Bearded Vulture , Cape Vulture, Black Eagle Aquila verreauxii, Black Stork Ciconia nigra. Of these the vulture species were considered at highest risk of wind farm development on the escarpment.

Bearded Vulture

Bearded Vultures have two sub-species recognised on plumage characteristics: G barbatus barbatus occurs in Europe, the Himalayas and North Africa while G barbatus meridionalis occurs in East and Southern Africa. Total global population is estimated at 2000-10,000 individuals. In 2014, Bearded Vulture was uplisted on the IUCN red list from Least Concern to Near Threatened. However, the population in Lesotho / Drakensberg is evaluated as Endangered in the red list for South Africa and Lesotho but Kruger (2014) considers the true status as critically endangered, with an estimated 100-220 breeding pairs (Kruger 2014). Their breeding range has declined by 27% (now restricted to 28,127km2) and breeding density by 20% (3.9 pairs per 1000 km2) in five decades, and the population faces a high risk of extinction (Kruger 2014). They nest in pairs on high cliffs, generally above 1800m, and have one chick annually. Satellite tracking studies indicated these vultures have large home ranges - especially non-breeding sub adults which cover thousands of square kilometres and can fly up to 700 km per day. They are threatened primarily by poisoning from feeding on poisoned carcasses, habitat degradation, and collision with powerlines. Reintroduction programmes have been attempted or are underway in Kenya and Spain, and vulture feeding stations are provided in several places globally.

Cape Vulture


The Cape Vulture (Gyps coprotheres) distribution is limited to southern Africa. It is listed as Vulnerable and has an estimated population size of less than 8000 individuals. Cape Vultures live in colonies of less than 10 to over a thousand birds on high steep cliffs. Many colonies are now inactive and the species is extinct in several previously recorded locations. They are under threat for the same reasons given for Bearded Vulture, as well as linked to inappropriate tourism development. Feeding stations are provided in some areas and helping to maintain some colonies.

Vultures are particularly collision prone with wind turbines as they tend to use thermal uplift winds rising from the altitudinal gradients to become and stay airborne. In addition, vultures tend to forage while looking down and the top of the escarpment is often shrouded in cloud or mist with poor visibility.

Regional Context

The project area lies within the Maloti Drakensberg Transfrontier Conservation and Development Area which was the subject of a 5-year project between South African and Lesotho called the Maloti Drakensberg Transfrontier Project (MDTP) with the aim of enhancing biodiversity conservation and sustainable land management. The MDTP area includes the Maloti Drakensberg Transboundary World Heritage Site, which runs the length of the escarpment, as well as the Royal Natal National Park which adjoins the wind farm site on the South African side and which includes the iconic Mont-aux-Sources amphitheatre. The nomination and approval of the inclusion of Sehlabathebe National Park in Lesotho as part of the Maloti Drakensberg Transboundary World Heritage Site requires Lesotho to evaluate impacts of wind power projects on vulture populations and the surrounding escarpment (IUCN 2013).


A comprehensive conservation planning study was undertaken for the MDTP (MDTP 2007) to collate existing and new biodiversity data for the Lesotho Highlands and identify conservation priorities for the region. The study included detailed mapping of wetlands, flora, degradation, rivers, fish, and priority bird species and integrated these spatial datasets to identify Lesotho’s conservation priorities (see Figure 2 and 3). They provided a valuable resource for evaluating the wind farm site sensitivities to highlight potential conflicts with conservation priority areas and sensitive features.


Figure 2. Wind Farm Site Overlap with Oxbow – Senqu Priority Area and Bird Buffer Zones

Figure 3. Conservation Priorities for the Lesotho Highlands (MDTP 2007).









Windfarm Process and Results

Activities undertaken involved the following steps:
1. The wind farm site was mapped and assessed in the context of the MDTP conservation planning outputs to identify particular biodiversity risks posed by the project. This highlighted the overlap of the wind farm site with the Oxbow-Senqu conservation priority area in the north of the country.
2. All available data for nesting sites for collision risk birds collected for the country since 1990 in the possession of the ornithologists on the team was collated.
3. A helicopter survey was undertaken of the wind farm area (including the Drakensberg escarpment) to obtain new bird data and verify the status of previously recorded nest sites. In total, 3-4 recent or active Bearded Vulture nest sites were recorded within 10km of the proposed wind farm of which one was only 2km away. One active Cape Vulture colony (with six nests) was located only 6 km from the nearest turbines, and many other colonies (including one comprising over 20 nests) and one with over 100 nests were found within a 30 km radius of the windfarm.
4. Buffer zones of different sizes were mapped around recorded nest sites based on consideration of bird collision risk as indicated in Table 1 and Figure 4.
The results showed a high level of overlapping bird buffer zones with the wind farm site (Figure 4).



Figure 4. Wind Farm Site Overlap with Oxbow – Senqu Priority Area and Bird Buffer Zones

Table 1. Bird Buffer Zone Distances Applied



Bird Species

Buffer Distance

Bearded Vulture (Gypaetus barbatus)

  • 10km

Cape Vulture
(Gyps coprotheres)




  • 15km for colonies with 10-25 nests




  • 20km for colonies with >25 nests

Southern Bald Ibis (Geronticus calvus)

  • 2.5km for colonies with <10 nests

Verraux¦s Eagle (Aquila verreauxii)

  • 5km with >10 nests

Black Stork
(Ciconia nigra)

  • 5km







Note: more recent analysis of satellite tracking data suggests that adult Bearded and Cape Vultures tend to forage within 15km of nests (Rushworth & Kruger 2014), although Cape vulture may forage up to 40km from colonies.

5. Consultation with conservation stakeholders from Ezemvelo KZN Conservation Authority raised significant concern related to collision risks with birds and bats, and potential impacts on the status of the Maloti Drakensberg Transboundary World Heritage Site due to the proximity of the wind farm and risks to its wilderness experience by hikers / tourists.



Key Recommendations of the Study

Due to the high potential risks of the project on birds, particularly vultures, and on the wilderness character of the area adjoining the world heritage site, the study indicated the windfarm was a potential fatal flaw. It was recommended that the EIA consider an alternative site to the southwest of the proposed site where bird collision risk appeared to be lower. The wind farm project and EIA was subsequently terminated.


Follow Up Activities

Similar concerns have also been raised about another smaller wind farm project located further south near Letseng Mine. This windfarm has been authorised by the Ministry of Environment, Tourism and Culture (MINTEC) in Lesotho despite significant opposition from conservation stakeholders (Yeld 2013; BirdLife 2013). Birdlife South Africa have since offered to assist the Lesotho Government with providing guidance on wind farm development and have prepared a Memorandum of Agreement with MINTEC to work together with a view to assist with developing best practice guidelines and a strategic environmental assessment of renewable energy in the country.


Subsequent research studies have modelled habitat usage by Bearded Vultures in the Drakensberg region from 5 years of data for 21 satellite tracked birds (Rushworth & Kruger 2014; Kruger 2013). These studies confirmed the proposed windfarms to be located in high bird risk areas (Rushworth & Kruger 2014; Reid et al 2015). Analysis of tracking data showed vultures tended to actively select ridge tops and upper slopes for foraging and that Bearded Vultures spend 53% of their flight within the blade sweep range of turbines (<100m height) while Cape Vulture spent 62% within this zone. Bearded Vultures were recorded to fly below 90km/hour. Analysis of increased collision risk posed by the two proposed wind farms indicated the vulture population in Lesotho is conservatively expected to decline at twice the present rate, reaching extinction in just over 100 years. This rate is expected to increase with expanding networks of powerlines andincreased incidence of poisoning, The study concluded that the only practical mitigation is to locate windfarms in areas of low vulture activity (Rushworth & Kruger 2014).
These studies have provided additional support for highlighting the significant risks posed by wind farm sites in Lesotho and will hopefully lead to improved decision making on the siting of wind farms.
Conclusions
The wind farm scoping study benefitted immensely from:

  1. access to robust spatial data from conservation planning studies

  2. information from satellite tracking studies

  3. available bird nest data for the project area, and

  4. ornithologists on the team with first-hand experience of bird surveys and nest site data in Lesotho collected over a period of 20 years.

The wind farm development did not proceed further for financial reasons.


References
Birdlife SA. 2014. Controversial Windfarm in Lesotho Gets Go-Ahead. Birdlife news (website)
ERM, 2012. Draft Scoping Report: Proposed LHPP 150MW Wind Farm, Lesotho.
IUCN, 2013. IUCN Evaluations of Nominations of Natural and Mixed Properties to the World Heritage List.

MDTP 2007. Spatial Assessment of Biodiversity Priorities in the Lesotho Highlands. Report for Maloti Drakensberg Transfrontier Project. Report by J Hughes, G Benn and M Laros.


Kruger, S. 2014. An Investigation into the Decline of the Bearded Vulture Gypaetus barbatus in Southern Africa. PhD Thesis, UCT: Percy Fitzpatrick Institute of African Ornithology
Kruger, S., Reid, T., and Amar, A. 2014. Differential Range Use between Age Classes of Southern African Bearded Vultures Gypaetus barbatus. PLoS ONE 9(12): e114920.doi:10.1371/journal.pone. 0114920
Reid, T, Kruger, S., Whitefield, D. & Amar, A. 2015. Using spatial analyses of bearded vulture movements in southern Africa to inform wind turbine placement. Journal of Applied Ecology. In Press.
Rushworth, I & Kruger, S. Wind farms threaten southern Africa’s cliff-nesting vultures. Ostrich, 2014: 85(1) 13-23.
Yeld, 2013. Windfarms threatening species. www.iol.co.za/scitech/science/environment/wind-farms-threatening-species-1.1539850#.Uo0P38Rmim5
World BirdWatch 2014. Threat to Vultures as Lesotho Wind Farm Goes Ahead. Flyway News, page 4.



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