Farmers’ conservation practice is critical to the development of effective watershed management. Overall, farmers’ conservation practice was not fair. Riparian buffers are transition zones between water and land that link terrestrial upland ecosystems to stream, river, lake, or wetland ecosystems and provide important functions, such as protecting and improving water quality etc. Depending on the needs and hydrological, biological, and physical characteristics of the site, the widths of existing riparian and wetland buffers range from 10 to 500 m (Klemas 2014). In the present study, most farmers are unable to tell the distance of buffer zone from the reservoir, even they don’t know about the buffer zone remark marked in the reservoir. Agricultural activities and others like pasture overwhelm the buffer zone of the study area. Such cultivation of marginal areas within the watershed (Fig. 2A & B) may exacerbate intensified soil erosion and reservoir sedimentation (Fig. 3B). Robert et al. (2003) also describe the fact that farming practices near streams can increase soil run-off and transportation of chemicals into streams. Loss of soil due to such kind of unwise farming system not only cause siltation of the dam, it also degrade fertile land for agriculture, which later causes food insecurity, because these cause serious challenge to agricultural productivity and economic growth (Mulugeta 2004).
These activities might be related to increased need of means of subsistence because of their poor life style. During discussion and open-end question, they remarked that the compensation payment paid when displaced from their previous place was not enough, there are no off-farm activities to reduce the pressure exerted on local natural resource, and therefore we are forced to exploit the resource irresponsibly. The application of chemical fertilizer is common in Ethiopia to increase yield / productivity than before. Farmland is the main landuse type hence increase agricultural land needs increased use of agrochemicals, which may have resulted in higher pollution loads to the rivers and lakes (Mateo-Sagasta et al. 2017) through storm water runoff.
The removal of woody species and other vegetation part would facilitate the flow of sediment, organic matter, nutrient and pesticides in to the reservoir upsetting the aquatic ecology. in addition to unwise farming ( Fig. 2), cutting trees for fire wood, the quest for fire wood/charcoal production in the sub watersheds also encroached the very small patch of trees without replacement (Fig. 4). Such activities may have resulted in plant species disappearance and animals. Based on open-ended question and FGDs, they told us animal like lion (Leenca), tiger (Qeerransa), pig (boyyee), warthog (karkaarro), Menelik's bushbuck (bosonuu), Oribi Antelope (kuruphee), Hippo (Roobii). Buffalo (gafarsa), and plant species Cordia africana (Waddessa), Hagenia abyssinica (Koosso), Pouteria adolfi-friederici (Kerero), Ficus species (Oodda, qilxu), Podocarpus falcatus (birbirsaa), Rhus ruspolii (xaxeessa), Accacia abysinica (laaftoo), rukeenso /known for charcoal/, satiyaa are among the lost flora and fauna.
Farmers stated that the current conservation practice was not appropriate. Watershed conservation practices only focussed on certain areas. For example, Gabion constructed to prevent soil erosion around Tiroafeta district (Fig. 6) is not consistent throughout the sub watersheds. There are areas where exposed to gulley erosion (Fig. 5). Most of them (67.9%) do nothing in group to protect watershed degradation (Table 4), for example the destruction of foot paths needs care as part of watershed management before the situation become intense because watershed management involves also common property resources like roads and footpaths, and vegetation along streams and rivers (Swallow et al., 2001).
During FGDs two elder farmers raised areas even after implementation of conservation measure, are eroded from year to year, maintaining these areas seem difficult. For example, vetiver grass planted to protect erosion were also damaged due to landslide and erosion (Fig. 7). So, in spite of conservation progress in the Gilgel Gibe watershed land degradation is still continuing.
Farmers involved to prevent their farmland from erosion individually only when it happens (during rainy season), this may be associated with lack of proper coordination and reduced responsibility feeling. This is also supported during the interview and FGDs (Fig. 8). In addition, they have no frequent contact with DAs (Development Agents).
The expansion and formation of gully is one of the main difficulties in degraded watersheds, it reduces the cultivable area and grazing lands, assist erosion from upstream-degraded landscapes and carry a huge volume of sediment to posing a problem of siltation in downstream dams, rivers (Gebregziabher et al. 2016). There are sub-watershed areas in critical conditions that needs priorities, for example the one in Omo nada woreda (Asendabo) highly exposed to gully erosion near to the dam (Fig. 5), which seems lack of integrated approach between upland and lowland or fail to share information to protect soil degradation (Table 4). Therefore, it is essential to manage along the entire route including upland soil loss, sediment accumulation, and channel bed erosion (Wortmann et al. 2008).
Majority of the farmers feed their cattle from the farmland. The burden applied on farmland for grazing of animals could cause vegetation loss, physical trampling of soil during the dry season and soil compaction in wet season which will assist wind erosion and decrease infiltration and increase runoff. Hubbard et al. (2004) has also found that grazing animals and pasture production can negatively affect water quality through erosion and sediment transport in to surface water. Beside, farmland grazing may cause difficulty in cultural weed control mechanism because of the distribution of their seeds through animal dung.
Significant test about farmers practice in watershed management (Table 5) reveals, there was a difference in current conservation practice, (especially the type of soil conservation activities) and significant difference also exists in noticing conservation practice as traditional management activity in the area. Majority of the farmers (59%) suggested that conservation could not be practiced as traditional management activity in the area. In areas where prevention measures were done (physical conservation activities like gabion), sediment is accumulated behind the constructed gabion (Fig. 6), but proper tree species (indigenous to the area) were not planted to strengthen prevention of soil erosion. Studies also indicated that lack of the integration of physical and biological conservation activities would seem environmentally, economically, and socially unacceptable, because watershed management includes the treatment of land by using proper biological and physical measures (Lakew et al. 2005).
It was understood by Governments and nongovernmental organizations (NGOs) that watershed conservation could not be realized without voluntary involvement of local people (Pretty and Ward 2001). Beside conservation activity farmer’s participation is also essential during planning of sustainable management of land and water resources (Habtamu 2011) because they are closer to the difficulties, and conscious to issues that omitted by professionals. In the study area, majority of farmers in the open-ended question and focus group discussion indicated that they are discouraged because of lack of rational use of local resource. They are not benefited from the nearby resource. They blamed that “we are displaced from our land for the construction of the dam but we are not using electric power, pure drinking water and no free / communal grazing land for our cattle”. Robert et al. (2003) suggested that both government policy, farmers’ motivations and attitudes could have influence on conservation practices and agricultural landscape patterns.