1970s to 2012, was reviewed with an assessment
of the effects of watershed interventions on land
use and land cover dynamics and their impacts
on erosion (e.g., Alemayehu et al. 2009; Fenta
et al. 2016).
The different watershed management interventions that have been implemented since the
2000s can be categorized in physical and biological (Mekonen and Tesfahunegn 2011; Alemu and
Kidane 2014). Physical interventions include:
hillside stone terraces, soil bunds, stone bunds and
check-dams while biological interventions mean
grassed waterways, reforestation, exclosure (protected areas), pits and agronomic practices (compost, hedge cropping). The implemented
interventions varied across sites as only physical
SWC was dominant in some watersheds, whereas
integrated biological and physical SWC were both
well established in others. Qualitative and quantitative data were collected and reviewed, then
analyzed using descriptive statistics. Outputs were
assessed using graphical and statistical indicators
(e.g., mean, percentage).
3 Results and Discussion
3.1 Overview of the Impacts
of Watershed Interventions
in Ethiopia
The implemented SWC measures (physical and
biological) as part of watershed management
practices in the last three decades were successful
in reducing the challenges of land degradation at
many sites in the Tigray region (Table 2). In some
watersheds, vegetation coverage improved by
85%, the number of new wells increased 7- to 9fold, and soil loss decreased by 80% compared to
the situation before the implementation of the
watershed management interventions. The food
security of the local community increased by 56%
after the watershed management interventions
were implemented. An example of such a successful watershed intervention is Abraha-Atsbaha
(Gebregziabher et al. 2016). Field observation,
discussion with farmers and DAs, and existing
reports indicated that the Gerebshelela, MaiNegus, and Medego watersheds had a less successful response to the integrated watershed
interventions implementation. This could be
because of the lower appropriateness of the
interventions to local conditions, social and cultural factors, and governance issues.
In agreement with results presented here, in
the Agula watershed (northern Ethiopia the area
under irrigation increased from 7 ha before the
intervention to 222.4 ha post-intervention and
the area under dense forest also increased from
32.4 to 98 ha (Alemayehu et al. 2009). However,
the nature and scale of the impacts of the
watershed management interventions vary considerably across the different watersheds in the
Tigray region. The factors that contribute to the
variability in the extent of success of watershed
management interventions are multidimensional,
including biophysical (e.g., lithology and
upstream–downstream hydrological linkages),
and institutional and socioeconomic elements
(Gebregziabher et al. 2016). This variability
could also be associated with variability in the
understanding of the implementation policy (capacity), and commitment of the implementers
(e.g., extension staff, researchers, and decision
makers) and the level of acceptance of the local
people towards the adoption and dissemination
of watershed management technologies (World
Bank 2008; ATA-MOA 2014).
In addition, field observations and reports have
indicated that stone bunds built across the landscape (watershed) retained (deposited) sediment
of up to 65 t ha
−1 year
−1 (Mekonen and Tesfahunegn 2011), and a sediment depth of 0.20–
0.90 m in the bunds on cultivated land and up to
1.5 m in check dams (Fig. 2). Moreover, sheet
and rill erosion decreased as much as 68% in the
Tigray region (Gebremichael et al. 2005; Mekonen and Tesfahunegn 2011; Fenta et al. 2016).
Reduction in soil loss by 80%, increased production area by 20 to 50% as marginal land was
rehabilitated and brought back into cultivation,
and a threefold increment in crop production was
reported for the Abraha-Atsbaha watershed in the
Tigray region (Worku and Tripathi 2015;
Gebregziabher et al. 2016). Such positive impacts
of watershed management interventions in many
170
G. B. Tesfahunegn and E. T. Ayuk
of the effects of watershed interventions on land
use and land cover dynamics and their impacts
on erosion (e.g., Alemayehu et al. 2009; Fenta
et al. 2016).
The different watershed management interventions that have been implemented since the
2000s can be categorized in physical and biological (Mekonen and Tesfahunegn 2011; Alemu and
Kidane 2014). Physical interventions include:
hillside stone terraces, soil bunds, stone bunds and
check-dams while biological interventions mean
grassed waterways, reforestation, exclosure (protected areas), pits and agronomic practices (compost, hedge cropping). The implemented
interventions varied across sites as only physical
SWC was dominant in some watersheds, whereas
integrated biological and physical SWC were both
well established in others. Qualitative and quantitative data were collected and reviewed, then
analyzed using descriptive statistics. Outputs were
assessed using graphical and statistical indicators
(e.g., mean, percentage).
3 Results and Discussion
3.1 Overview of the Impacts
of Watershed Interventions
in Ethiopia
The implemented SWC measures (physical and
biological) as part of watershed management
practices in the last three decades were successful
in reducing the challenges of land degradation at
many sites in the Tigray region (Table 2). In some
watersheds, vegetation coverage improved by
85%, the number of new wells increased 7- to 9fold, and soil loss decreased by 80% compared to
the situation before the implementation of the
watershed management interventions. The food
security of the local community increased by 56%
after the watershed management interventions
were implemented. An example of such a successful watershed intervention is Abraha-Atsbaha
(Gebregziabher et al. 2016). Field observation,
discussion with farmers and DAs, and existing
reports indicated that the Gerebshelela, MaiNegus, and Medego watersheds had a less successful response to the integrated watershed
interventions implementation. This could be
because of the lower appropriateness of the
interventions to local conditions, social and cultural factors, and governance issues.
In agreement with results presented here, in
the Agula watershed (northern Ethiopia the area
under irrigation increased from 7 ha before the
intervention to 222.4 ha post-intervention and
the area under dense forest also increased from
32.4 to 98 ha (Alemayehu et al. 2009). However,
the nature and scale of the impacts of the
watershed management interventions vary considerably across the different watersheds in the
Tigray region. The factors that contribute to the
variability in the extent of success of watershed
management interventions are multidimensional,
including biophysical (e.g., lithology and
upstream–downstream hydrological linkages),
and institutional and socioeconomic elements
(Gebregziabher et al. 2016). This variability
could also be associated with variability in the
understanding of the implementation policy (capacity), and commitment of the implementers
(e.g., extension staff, researchers, and decision
makers) and the level of acceptance of the local
people towards the adoption and dissemination
of watershed management technologies (World
Bank 2008; ATA-MOA 2014).
In addition, field observations and reports have
indicated that stone bunds built across the landscape (watershed) retained (deposited) sediment
of up to 65 t ha
−1 year
−1 (Mekonen and Tesfahunegn 2011), and a sediment depth of 0.20–
0.90 m in the bunds on cultivated land and up to
1.5 m in check dams (Fig. 2). Moreover, sheet
and rill erosion decreased as much as 68% in the
Tigray region (Gebremichael et al. 2005; Mekonen and Tesfahunegn 2011; Fenta et al. 2016).
Reduction in soil loss by 80%, increased production area by 20 to 50% as marginal land was
rehabilitated and brought back into cultivation,
and a threefold increment in crop production was
reported for the Abraha-Atsbaha watershed in the
Tigray region (Worku and Tripathi 2015;
Gebregziabher et al. 2016). Such positive impacts
of watershed management interventions in many
170
G. B. Tesfahunegn and E. T. Ayuk