Impact of Socioeconomic Factors and Environmental Changes on Sri Lanka’s Central Highlands - Impact of Global Changes on Mountains: Responses and Adaptation - page 359

productivity result is reduced and increased reliance on environmentally
inappropriate agricultural practices as well. Due to all these causes,
massive landslides occur during the rainy seasons. According to the
records of the Road Development Authority (Yogaratnam 2010), the total
cost of maintaining 1 km of A and B class roads in Nuwara-Eliya District
of Central Highlands has increased by almost 350% during the past fi ve
years (Yogaratnam 2010). According to studies conducted by Senanayake
on factors associated with the occurrence of landslides in Sri Lanka, human
activities in the cultivation of tea, rubber, coconut, paddy and vegetables
contribute to 35, 20, 10, 13, and 8% respectively (Senanayake 1993, cited by
Hewawasam 2010) (Table 15.3).

Table 15.3. Extent of different land use types and estimated soil erosion rates in the UMC
(Upper Mahaweli Catchment).

Bedrock erosion rate 1
(mm ky -1 )
Dense forest 356.6 100 37
Degraded forest and scrubs 435.7 2500 925
Degraded grasslands 141.9 3000 1110
Poorly managed seedling tea 3454.8 5200 1924
Seedling tea with some conservation 252.7 1500 555
Vegetative-propagated tea 114.9 200 74
Paddy 285.7 300 111
Home gardens 537.7 100 37
Shifting cultivation and tobacco 484.6 7000 2590
Market gardens 163.6 2500 925
1 Converted into corresponding bedrock erosion considering density as 2.7 g per cm 3
Source: Hewawasam 2010

Land use type Area (km 2 ) Soil loss

(t km -2 y -1 )

Water stream mismanagement

Many rivers and streams fl ow through catchment areas that are densely
populated regions in Central Highlands and are negatively impacted by
urbanization. The most consistent and pervasive effects are channeling
due to settlements, solid waste mismanagement, stream pollution, and an
increase in water discharge. In Akurana at Pinga Oya River (Tributary of
Mahaweli), the stream is being channelized nearly 3 km without proper
planning and solid waste issues create massive risks (Dissanayake 2002,
Dissanayake 2009, Mahees 2009). In Geli Oya at Mahaweli River, similar
effects as in Pinga Oya and in Meda Ela have been registered (Dayawansa
2008), where the effects of urbanization described above brought about
changes to the stream channel width, the water quality and the stream load.
Also, the river banks were smoothened by the construction of concrete walls.