Soil And Water Conservation Measures Research Articles

Effects of soil and water conservation interventions on some physico-chemical properties of soil in hamelmalo and serejeka sub-zones of eritrea

Extensive Soil and Water Conservation (SWC) interventions were carried out in Eritrea to arrest widespread land degradation, but their effect on soil physico-chemical properties has not yet been studied and hence, the present study was conducted to assess the influence of the SWC interventions on some soil properties in Hamelmalo and Serejeka sub-zones of Eritrea. Stratified sampling method was used to collect composite soil samples from conserved and non-conserved fields for comparison. The findings indicated that soil pH, moisture and clay contents were significantly higher in the conserved fields than in the non-conserved fields but it was not so for bulk density, electrical conductivity, organic matter, total nitrogen, extractable phosphorus and exchangeable calcium and magnesium. Thus, the study suggested that physical SWC measures should be integrated with biological and agronomic SWC measures and should be supplemented with good field management practices for better results.

Effects of soil conservation measures on soil erosion in the Yunnan Plateau, southwest China

Soil and water conservation (SWC) measures are among the most important ways to control soil erosion in mountainous areas. However, little is known about the application of SWC measures on soil erosion over large areas. We developed a new framework for investigating the distribution of engineering measures by using high-resolution remote sensing images at a large scale, and we assessed the soil conservation effects of those measures on the Yunnan Plateau (YP) in China using the Chinese Soil Loss Equation (CSLE). We detected 43,398 km2 of soil conservation measures on the YP, accounting for 53% of farmland. The area of conservation measures decreased with an increase in slope gradient. Different types of engineering measures had different spatial distribution patterns, and together they conserved 5.08 × 108 t of soil each year on the YP. The effects of engineering measures on soil erosion decreased with an increase in slope. Furthermore, more than 82% of soil loss from farmlands was attributed to areas without engineering measures, and steep-slope farmland without such measures was the main source of soil erosion on the YP. Our results suggest that engineering measures were effective in soil conservation, but the effects varied with topography on the YP. We suggest that further studies focus on the relationships between the soil erosion and grain supply of farmlands without engineering measures to provide a basis for the formulation of land use planning policy in China.

Streamflow and Sediment Declines in a Loess Hill and Gully Landform Basin Due to Climate Variability and Anthropogenic Activities

Streamflow and sediment runoff are important indicators for the changes in hydrological processes. In the context of environmental changes, decreases in both streamflow and sediment (especially in the flood season) are often observed in most of the tributaries of the middle Yellow River in China’s Loess Plateau. Understanding the effect of human activities could be useful for the management of soil and water conservation (SWC) and new constructions. In this paper, changes in streamflow and sediment during the flood season (June–September) of the 1966–2017 period in a typical loess hill and gully landform basin were analyzed. Basin-wide rainfall of the flood season decreased nonsignificantly with an average rate of −0.6 mm/flood season for the whole study period by using the trend-free pre-whitening based Mann–Kendall trend test, while the decreasing rate was weakened on the time scale. A remarkable warming trend (1985–1999) and two decreasing trends (1966–1984 and 2000–2017) were observed, and the overall increasing trend could be found in air temperature series with a rate of 0.01 °C/flood season during the study period. Statistical models were developed to describe the rainfall-runoff and rainfall-sediment processes in the pre-impact period (when the hydrological series was stationary). Furthermore, the relative effects of climate variability and human activities on hydrological changes were quantified. Results proved the dominant role of human activities (versus climate variability) on the reductions of both streamflow and sediment load. The relative contribution of human activities to streamflow decrease was 84.6% during the post-impact period 1995–2017, while the contributions were 48.8% and 80.1% for two post-impact periods (1982–1996 and 1997–2017), respectively, to the reduction of sediment load. Besides, the effect of the exclusion of anomalous streamflow or sediment events on change-point detection was also analyzed. It indicated that the anomalous events affect the detection of change points and should be given full consideration in order to decide whether to remove them in the change-point detection. Otherwise, the full series with anomalous samples will completely affect the attribution results of hydrological changes. We also suggest that large-scale SWC measures with different construction quality and operational life could intercept and relieve most floods and high sediment concentration processes, but may amplify the peaks of streamflow and sediment when the interception capacities are exceeded under the condition of extreme rainstorm events.

Economic benefits of soil and water conservation measures at the sub-catchment scale in the northern Highlands of Ethiopia

Soil and water conservation (SWC) interventions are needed to control rainfall-driven erosion, and profitability of SWC measures at the sub-catchment scale emerges as the principal reason for their adoption. This study carried out a cost–benefit analysis of SWC measures in mountainous agricultural catchments. Physical data were obtained through field measurements of discharge, sediment and nutrient loss at the sub-catchment scale with and without SWC measures. The major cost benefits of various measures implemented in the study area were quantified using net present value (NPV), and direct market prices were employed in valuing the cost of items required for crop production. The results revealed that sediment loss decreased by 8.78 Mg ha−1 y−1 (46.8%) due to SWC measures, and the cost of production inputs, such as fertilizer (urea) and lime, was reduced by $17.97 ha−1 y−1 and $3.63 ha−1 y−1, respectively. Furthermore, crop yield was enhanced by 13% for teff, 19.4% for sorghum and 19.42% for chickpeas, which is equivalent to economic returns of $102, $96.9 and $140.25 ha−1 y−1, respectively. The total discounted cost of SWC interventions was about $331.74. This includes establishment costs, maintenance costs, input costs and the costs resulting from lost productive land. In sum, the total discounted benefits of SWC measures were the enhancement of crop production, a reduction in lime requirement and a reduction in the loss of total nitrogen and sediment, estimated at about $809.42. Hence, it is possible to deduce that SWC measures reduced nutrient depletion and greatly improved crop yield with a NPV of $477.68 ha−1. The results strongly suggest that SWC measures in the study sub-catchment, as well as in nearby areas with a similar indigenous SWC adoption strategy, topographic conditions and agroclimatic characteristics, should be maintained.

Investigation method for regional soil erosion based on the Chinese Soil Loss Equation and high-resolution spatial data: Case study on the mountainous Yunnan Province, China

Investigating soil erosion at the regional scale is challenging because of the difficulties with balancing the accuracy against the cost, especially in areas where the terrain and land use are complex. In this study, we developed a feasible approach to evaluating soil erosion at the regional scale that uses the Chinese Soil Loss Equation (CSLE) and 0.5 m high-resolution Worldview Satellite images, from which soil and water conservation (SWC) engineering practices were interpreted and included into the model as the E factor. We took the mountainous Yunnan Province of southwest China as a case study, and successfully tested this method and estimated the erosion modulus and soil erosion intensity of this region. The model was validated against with measured data derived from 47 runoff plots; the results showed that the coefficient of determination of CSLE was 0.89, which indicates high accuracy. The average erosion modulus was 12.56 t·ha−1·a−1 at the provincial level, and areas with a high erosion modulus were mainly distributed in the central and northeast parts. The total soil erosion area was 104,727.74 km2, accounting for 27.33% of the total area. More than 77% of above middle erosion occurred in farmlands. Our study is the first effort at incorporating high-precision SWC engineering measures data into regional soil erosion investigation. Our approach reduces the soil erosion estimation error caused by low data accuracy, overcomes the technical bottleneck for obtaining information on regional SWC measures, and provides a practical and low-cost method for evaluating regional soil erosion.

A method for data downscaling in estimations of food-provisioning service in a mountainous region

The food provisioning service (FPS) represented by grain yield is strongly affected by the slope and soil and water conservation (SWC) measures in a mountainous region. Current FPS assessment methods mainly depend on regional census statistical data and do not take the local variability in slope and SWC measures into consideration, which may lead to errors. Based on field monitoring, this study qualified the relationship between slopes, SWC measures, and crop yields, and proposed a data downscaling method (DDM) to estimate FPS in a mountainous region. The results showed that corn yield per hectare (CYPH) was negatively related to slope; a one-degree increase in slope resulted in a 267 kg∙ha−1 decrease in CYPH on farmland without SWC measures (FWOM) and a 336 kg∙ha−1 decrease in farmland with SWC measures (FWM). Although FWOM accounted for 52.47% of the total farmland in the study area, it only provided 29.86% of FPS. FWM on a slope < 15° was the key area for providing FPS, which indicated that the traditional FPS assessment method (using the census statistical data) was inaccurate compared with DDM. DDM can help to improve the accuracy of ecosystem services assessment and trade-off analyses, and thus contribute to more targeted land use planning in a mountainous region.

Conservation and production impacts of soil and water conservation practices under different socio-economic and biophysical setting: a review

In Ethiopia, the increase in land degradation mainly in the form of soil erosion necessitates implementation of soil and water conservation (SWC) practices. So far impact evaluation studies are scattered and not comprehensive. In this paper detailed quantitative review of impact of SWC practices under different climate and socio-economic setting were done on runoff, soil loss, siltation, soil fertility and crop yield. Up to 1980s, expert and government considered reduction of soil loss and runoff as big achievement. This was not in line with the interest of subsistence farmers who need short term benefit. The reduction of soil loss, runoff and siltation of reservoirs are positively acknowledged by majority researchers and have several beneficial effects: increase soil moisture content, groundwater recharge, increased in situ sediment deposition, making the hill slope suitable for agriculture and reduce siltation. Regarding production objective, SWC practices have mixed impact (positive and negative) on crop yield and soil fertility. In this review it was found that 62.5% of the reviewed materials revealed that SWC measures have positive impact on soil fertility either in increasing or maintaining. In contrast, 25% showed SWC treated areas had lower soil fertility than untreated and 12.5% showed no significant change in soil fertility. In summary, the impact of SWC practices especially on soil fertility and crop yield varies depending on soil erosion degree before SWC implemented, design of SWC measures, crops, plows, socio-economic, soils types and climate mainly rainfall. The review in detail discussed why SWC practices have variation in impact on soil fertility and crop yield. Finally SWC practices are an action of no option for sustainable development and food security under current soil erosion and climate change.

Soil and water conservation measures reduce soil and water losses in China but not down to background levels: Evidence from erosion plot data

The efficacy of soil and water conservation measures (SWCMs) on reducing the loss of soil and water has been widely tested at the plot scale in China. However, an integrated comparison of the efficacy and an overall investigation of the controlling factors of the efficacy is absent. Therefore, an extensive dataset compiling erosion plot measurement of applying SWCMs on controlling soil loss and runoff in China was established in this study. In total, 848 erosion plots representing 2494 plot years were retained in this dataset which compiled from 108 publications and 2 data reports. The 15 most frequently tested SWCMs were identified and described. Soil loss ratio (SLR) and runoff ratio (RR) of each SWCMs was calculated to assess the efficacy of an SWCMs on reducing soil and water loss. The potential controlling factors, such as slope, slope length, annual precipitation, were evaluated for the controlling factor for both SLR and RR. Our results suggested that in general, applying the SWCMs can reduce soil loss by ca. 70% (overall SLR is 0.39 ± 0.02) and runoff by ca. 50% (overall RR is 0.54 ± 0.05), respectively. However, erosion rates on plots with SWCMs in China were, in general, still significantly higher than erosion rates measured under permanent vegetation cover land and, on average, ca. one order of magnitude higher than soil formation rates which required for a soil-neutral agriculture. On overall, the SLR presented a significant relation with topographic factors: positive with slope gradient and negative with slope length. This suggests that the support practice factor (P factor) of RUSLE model might be overestimated when values measured from plot scale are directly applied to larger areas (catchment or region scale). The SLR and RR values presented in this study can be applied for the planning of SWCMs in China and can be used to estimate the P factor when applying RUSLE model whereby the effect of topographic factors on SWCM efficacy can be accounted for.

Long-term effect of soil and water conservation measures on runoff, sediment and their relationship in an orchard on sloping red soil of southern China.

The effect of soil and water conservation measures (SWCMs) is usually dependent on time. Thus the trend in reducing runoff and sediment over time is a very important theoretical problem for evaluating the effectiveness of SWCMs. Moreover, there is still a lack of comprehensive assessment of water erosion dynamics following implementing SWCMs despite their ecological significance. Therefore, the long-term impact of SWCMs on runoff and sediment and their relationships was assessed for an orchard on sloping red soil in southern China. Overland flow and erosion sediment were continuously observed for 15 years on citrus experimental plots under one of four treatments: grass strips, strip intercropping, level terrace and clean-tillage. By means of Mann–Kendall trend tests and double cumulative curves, the time series of runoff and sediment under the different treatments were analyzed. Furthermore, we linked the effect of soil conservation and the relationship between runoff and sediment variation to determine the mechanism of conservation measures on sediment reduction. The results showed that the first 4 years was the key period to prevent soil erosion for this orchard, and then the intensity of soil erosion decreased below 500 t·km–2·a–1. Considering economic costs and ecological effect, grass strips were the best protective measure for this test situation. The fitted curves of the effect of SWCMs on sediment reduction over time showed an ‘L’ form, but on runoff there was an approximately horizontal line. The SWCMs did not change the rainfall–runoff relationship, but did change the runoff–sediment erosion relationship. The erosion reduction mechanism of SWCMs in the early phase was a joint function of reducing runoff and changing the runoff–sediment relationship, and in the post-stable phase it worked mainly by reducing runoff. The results provide the basis for rational allocation of SWCMs considering location and time.

Soil and Water Conservation in Burkina Faso, West Africa

Inadequate land management and agricultural activities have largely resulted in land degradation in Burkina Faso. The nationwide governmental and institutional driven implementation and adoption of soil and water conservation measures (SWCM) since the early 1960s, however, is expected to successively slow down the degradation process and to increase the agricultural output. Even though relevant measures have been taken, only a few studies have been conducted to quantify their effect, for instance, on soil erosion and environmental restoration. In addition, a comprehensive summary of initiatives, implementation strategies, and eventually region-specific requirements for adopting different SWCM is missing. The present study therefore aims to review the different SWCM in Burkina Faso and implementation programs, as well as to provide information on their effects on environmental restoration and agricultural productivity. This was achieved by considering over 143 studies focusing on Burkina Faso’s experience and research progress in areas of SWCM and soil erosion. SWCM in Burkina Faso have largely resulted in an increase in agricultural productivity and improvement in food security. Finally, this study aims at supporting the country’s informed decision-making for extending already existing SWCM and for deriving further implementation strategies.

Influence of soil and water conservation measures on soil fertility in the Beijing mountain area

Soil and water conservation (SWC) measures can be adopted to conserve soil and water and improve soil fertility. The degree to which SWC measures improve soil fertility is affected by the type of SWC measure, soil type, climate, etc. The purpose of this study was to study the effect of the main SWC measures implemented in the Beijing mountain area on soil fertility. Six runoff plots, including a fish pit (fallow) (FPF), fish pit (Platycladus orientalis L. Franco) (FPP), narrow terrace (fallow) (NTF), narrow terrace (Juglans regia L.) (NTJ), tree pan (Juglans regia L.) (TPJ), and fallow land (FL), were established to analyze the differences in soil fertility in the Beijing mountain area. Soil samples were collected in 2005 and 2015 from the six runoff plots. Soil particle size; soil total nitrogen (TN), total phosphorous (TP), total potassium (TK), alkali-hydrolysable nitrogen (Ah-N), available P (Av-P), and available K (Av-K); and soil organic matter (SOM) were measured. The soil integrated fertility index (IFI) was calculated. The results showed that the soil nutrient content and IFI significantly decreased from 2005 to 2015 in the FL plot and significantly increased in the five runoff plots with SWC measures. Compared to the other runoff plots with SWC measures, the FPP plot more significantly improved the soil nutrient content and IFI. The TN, Ah-N, Av-K, SOM, and IFI in the FPP plots increased by 98%, 113%, 61%, 69 and 47%, respectively, from 2005 to 2015. The IFI for the FPP, NTJ, and TPJ exceeded the average IFI of the farmland soil in the study region. The results indicated that the combination of engineering practices and vegetative measures effectively improved soil fertility. These results may be helpful for selecting SWC measures, land-use planning and monitoring and assessing soil fertility.

Multiscale temporal variability of flow-sediment relationships during the 1950s–2014 in the Loess Plateau, China

Flow-sediment relationships provide insights into the erosion and transport of materials within catchments. Investigating the flow-sediment relationships across multiple timescales can reveal trends related to the effects of natural and human-caused changes to catchments. This study chose fourteen main catchments in the Loess Plateau of China, which are the major sediment sources of Yellow River, to extract the temporal patterns of flow-sediment relationships during the 1950s–2014 period. The study revealed quantifiable effects of land use/cover changes (LUCC) on the variability of flow-sediment relationships. The LUCC induced by the soil and water conservation measures (SWCMs) during 1970–1999 and vegetation restoration campaign since 2000 resulted in significant reductions of annual streamflow, sediment yield and sediment concentration. The mean daily sediment concentration under different flow conditions also decreased greatly. The flow-sediment relationships revealed time dependence over different stages and time scales. Before 2000, the annual and monthly flow-sediment relationships could be generally characterized by the linear functions, and the power-law sediment rating curve was able to describe the daily flow-sediment relationship. As vegetation restoration campaign took effect, the flow-sediment relationship became much weaker, which could not be described by a clear relationship. This suggests that the variability of flow-sediment relationships over the entire period was mainly regulated by the vegetation restoration campaign. In addition, the sediment concentration exhibited a linear decreasing relationship with the area under land use/cover treatment. In this way, the study has brought out the roles of ecological restoration measures in controlling the temporal variability of flow-sediment relationships at the catchment scale.

Exclosures backed up with community-based soil and water conservation practices increased soil organic carbon stock and microbial biomass carbon distribution, in the northern highlands of Ethiopia

BackgroundLand degradation is a treat for natural resources in Tigray high lands of northern Ethiopia, where 30–50 percent of the soil productive capacity has been lost in the past 500 years. Restoration and management of degraded lands improve soil health through enhancing soil organic carbon (SOC) stock and microbial biomass carbon (MBC). The knowledge on SOC and MBC concentration and distribution is essential to refine soil management, thereby restoring the ecosystem. This paper quantified the effect of decades old community-based soil and water conservation (SWC) measures, mainly stone terraces, exclosure with and without stone terraces, and non-conserved communal grazing lands on the distribution of MBC and SOC stock.MethodsSoil sample collection was carried out using systematic sampling design. Transects parallel to each other and to the slope of the landscape were established. In each transect, three landscape positions (i.e., upper, middle, and foot slope) were formed. Composite soil samples were taken from four corners and center of 10 m × 10 m plot of each slope positions under the different SWC measures. Analysis of variance was used to determine the difference in SOC and MBC using SAS 9.2.ResultsTotal soil organic carbon concentration was significantly higher in exclosures as compared to terraces and non-conserved grazing lands. The highest mean value of SOC stock (29 Mg C ha−1) was recorded in exclosures with terraces followed by exclosures without terraces (24 Mg C ha−1) and terraces (21 Mg C ha−1), while the lowest (16 Mg C ha−1) was recorded in non-conserved communal grazing lands. Exclosures with terraces improved SOC stock by 64%, followed by exclosures without terraces by 37%, while terraces improved the SOC stock by 25% compared to non-conserved open communal grazing lands in the last 20 years. The upper (0–15 cm) soil depth had significantly (P < 0.05) higher (24 Mg C ha−1) SOC stock than the lower (15–30 cm) soil depth (20 Mg C ha−1). Microbial biomass carbon was the highest (640 mg kg−1 soil) in exclosures without terraces, followed by exclosures with terraces, (570 mg kg−1 soil), terraces (440 mg kg−1 soil), and non-conserved communal grazing lands (370 mg kg−1 soil).ConclusionExclosures supported with terraces improved and restored the SOC stock and microbial biomass carbon of degraded free grazing lands in the highlands.

The Effect of Community-Based Soil and Water Conservation Practices on Abundance and Diversity of Soil Macroinvertebrates in the Northern Highlands of Ethiopia

Soil and water conservation (SWC) practices in the northern highlands of Ethiopia have important implications for land restoration and biodiversity recovery. The present study determined soil macroinvertebrate (SMI) abundance and diversity in response to spatial conditions i.e., generated by different conservation practices, soil depth, and temporal seasonality with the wet and dry season. The SWC practices considered were exclosure + terrace, exclosure alone, terraces, and non-conserved grazing lands. Each SWC measure was selected in three sites that were considered as replications due to low heterogeneity in terms of human and livestock disturbances and biophysical factors. Soil macroinvertebrates were collected using a monolith according to tropical soil biology and fertility (TSBF) method. The highest density (55%) of SMI was found in exclosures followed by terraces 26%. Non-conserved communal grazing lands account for only 19% of the total. Shannon diversity index was significantly (P &lt; 0.05) higher (1.21) in the exclosures supported with terraces and the lowest (0.9) was observed in the non-conserved communal grazing lands. Diversity was also significantly (P &lt; 0.05) higher (1.26) in wet than dry season (0.70). The highest (41%) Sorensen similarity index among SMI was found between exclosures with terraces and exclosures alone during the wet season. The lowest (20%) Sorensen similarity index was found between terraces alone and exclosures with terraces in dry season. Soil macroinvertebrate abundance was higher in upper (0–10 cm) than lower (10–20 and 20–30 cm) soil depth. Soil macroinvertebrate abundance was positively and strongly correlated with soil moisture (R2 = 0.85) and soil organic carbon stock (R2 = 0.95). However, it was negatively (R2 = −0.71) correlated with bulk density. Generally, the abundance and diversity of SMI increased as exclosures and communal grazing lands are supported with terraces.

Effect of soil and water conservation on rehabilitation of degraded lands and crop productivity in Maego watershed, North Ethiopia

Many soil and water conservation (SWC) measures were undertaken to decrease land degradation in Ethiopia. However, evaluation of their performance is essential to understand their success or failure and readjusting accordingly in the future planning. Therefore, the objective of this study was to evaluate effectiveness of SWC measures in rehabilitation of degraded watershed and increase crop productivity in Maego watershed, Ethiopia. Seventy six sample plots were randomly taken from treated and untreated sub-watersheds for woody species and soil sampling. Crops yield was measured on top side, middle zone and below side of SWC structures. There were significantly higher woody species density and diversity, total nitrogen (TN), soil organic matter (SOM) and soil moisture in the treated uncultivated land than the untreated one. The highest tree and sapling species density and diversity, TN and SOM were recorded on the exclosure part of the treated sub-watershed. Landscape position affected soil fertility, but has no effect on woody species density and diversity. The highest barley and wheat yield was measured on top side of SWC structures. Therefore, physical SWC structures should be integrated with exclosure to enhance rehabilitation of degraded watersheds/landscapes. Integration of biological SWC measures that improve soil fertility are essential on the cultivated land of the watershed. Most of the existing SWC structures, especially the old ones are filled with accumulated sediment, so maintenance is needed.

Spatial Modeling of Soil Erosion Risk and Its Implication for Conservation Planning: the Case of the Gobele Watershed, East Hararghe Zone, Ethiopia

Soil erosion by water has accelerated over recent decades due to non-sustainable land use practices resulting in substantial land degradation processes. Spatially explicit information on soil erosion is critical for the development and implementation of appropriate Soil and Water Conservation (SWC) measures.The objectives of this study were to estimate the magnitude of soil loss rate, assess the change of erosion risk, and elucidate their implication for SWC planning in the Gobele Watershed, East Hararghe Zone, Ethiopia. Applying remote sensing data, the study first derived the Revised Universal Soil Loss Equation (RUSLE) model parameters in an ArcGIS environment and estimated the soil loss rates. The estimated total soil loss in the watershed was 1,390,130.48 tons in 2000 and 1,022,445.09 tons in 2016 with a mean erosion rate of 51.04 t ha−1 y−1 and 34.26 t ha−1 y−1, respectively. The study area was divided into eight erosion risk classes ranging from very low to extremely high. We established a change detection matrix of the soil erosion risk classes between 2000 and 2016. The change analysis results have revealed that about 70.80% of the soil erosion risk areas remained unchanged, 19.67% increased in total area, and 9.53% decreased, showing an overall worsening of the situation. We identified and mapped areas with a higher and increasing erosion risk as SWC priority areas using a Multi-criteria Decision Rules (MCDR) method. The top three priority levels marked for the emergency SWC measures account for about 0.04%, 0.49%, and 0.83%, respectively. These priority levels are situated along the steep slope areas in the north, northwest, south, and southeast of the Gobele Watershed. It is, thus, very critical to undertake proper intervention measures in upslope areas based on the priority levels to establish sustainable watershed management in the study area.

Factors influencing the adoption of physical soil and water conservation practices in the Ethiopian highlands

Soil and Water Conservation (SWC) structures have been constructed on cultivated land for nearly 40 years to reduce soil loss and improve crop yields and people's livelihoods in the Ethiopian highlands. However, the success of this huge effort has been mixed, and the main constraints have not been investigated in detail. This study was undertaken to identify the factors determining the adoption of SWC structures in the Ethiopian Highlands. Case study areas were selected from high-potential and low-potential areas. Data were collected from 269 farmers using face-to-face interviews, and through focus group discussions, key informant interviews and field observations. Binary logistic regression model and descriptive statistics were used to analyze the data. The result showed that the majority (87%) of the farmers interviewed were using SWC structures. Regionally, nearly all farmers in the low-potential areas and 56% of farmers in the high-potential areas constructed and were maintaining the structures properly. This disparity is due to the fact that in the low-potential areas there have been strong governmental involvement and technical and financial support, and hence the farmers there have a better understanding of the multiple uses of physical SWC structures than do farmers in the high-potential areas. In addition, off-farm activities and free grazing plays a substantial role. We can conclude that clear understanding of the benefits of SWC structures by farmers, active involvement and technical support from the government, and genuine participation of farmers in SWC practices were found to be main factors in the adoption of SWC measures.

Prediction of soil and water conservation structure impacts on runoff and erosion processes using SWAT model in the northern Ethiopian highlands

PurposeLand degradation due to soil erosion is a serious threat to the highlands of Ethiopia. Various soil and water conservation (SWC) strategies have been in use to tackle soil erosion. However, the effectiveness of SWC measures on runoff dynamics and sediment load in terms of their medium- and short-term effects has not been sufficiently studied.Materials and methodsA study was conducted in 2011 to 2015 in the Gumara-Maksegnit watershed to study the impacts of SWC structures on runoff and soil erosion processes using the soil and water analysis tool (SWAT) model. The study was conducted in two adjacent watersheds where in one of the watersheds, SWC structures were constructed (treated watershed (TW)) in 2011, while the other watershed was a reference watershed without SWC structures (untreated watershed (UW)). For both watersheds, separate SWAT and SWAT-CUP (SWAT calibration and uncertainty procedure) projects were set up for daily runoff and sediment yield. The SWAT-CUP program was applied to optimize the parameters of the SWAT using daily observed runoff and sediment yield data.Results and discussionThe runoff simulations indicated that SWAT can reproduce the hydrological regime for both watersheds. The daily runoff calibration (2011–2013) results for the TW and UW showed good correlation between the predicted and the observed data (R2 = 0.78 for the TW and R2 = 0.77 for the UW). The validation (2014–2015) results also showed good correlation with R2 values of 0.72 and 0.70 for the TW and UW, respectively. However, sediment yield calibration and validation results showed modest correlation between the predicted and observed sediment yields with R2 values of 0.65 and 0.69 for the TW and UW for the calibration and R2 values of 0.55 and 0.65 for the TW and UW for the validation, respectively.ConclusionsThe model results indicated that SWC structures considerably reduced soil loss by as much as 25–38% in the TW. The study demonstrated that SWAT performed well for both watersheds and can be a potential instrument for upscaling and assessing the impact of SWC structures on sediment loads in the highlands of Ethiopia.

Applying Ostrom’s institutional analysis and development framework to soil and water conservation activities in north-western Ethiopia

Sustainable land management is of utmost importance in Ethiopia and relies on Soil and Water Conservation (SWC) measures collectively implemented by smallholders through participatory processes. This paper contributes systematic evidence on how SWC strategies are implemented and how participation is operationalized. Drawing upon inductive, qualitative research, we explore the design, implementation and evaluation of SWC activities, as they relate to Ostrom’s Institutional Analysis and Development (IAD) framework, in order to determine how the activities can be made more appropriate, effective and sustainable. Findings show that on all levels of Ostrom’s framework, there are shortcomings in the SWC institutions, which have to be addressed with more participatory approaches, a change from top-down to bottom-up measures, and economic incentives for farmers to invest in SWC measures instead of e.g. compulsory labor, and the integration of so far neglected groups like youth, women and the landless.

Participatory assessment of soil erosion severity and performance of mitigation measures using stakeholder workshops in Koga catchment, Ethiopia

Farmers possess a wealth of knowledge regarding soil erosion and soil and water conservation (SWC), and there is a great demand to access it. However, there has been little effort to systematically document farmers' experiences and perceptions of SWC measures. Sustainable Land Management (SLM) has largely evolved through local traditional practices rather than adoption based on scientific evidence. This research aimed to assess soil erosion and performance of different SWC measures from the farmers' perspective by documenting their perceptions and experiences in Koga catchment, Ethiopia. To this aim, workshops were organised in three sub-catchments differing in slopes and SWC measures. Workshops included group discussions and field monitoring of erosion indicators and systematically describing the status of soil erosion, soil fertility and yield to assess the performance of SWC measures. Results show that farmers are aware of the harmful effects of ongoing soil erosion and of the impacts of mitigation measures on their farms. Sheet erosion was found to be the most widespread form of erosion while rill damage was critical on plots cultivated to cereals on steep slopes. The average rill erosion rates were 24.2 and 47.3 t/ha/y in treated and untreated farmlands, respectively. SWC reduced rill erosion on average by more than 48%. However, the impacts of SWC measures varied significantly between sub-watersheds, and farmers believed that SWC measures did not prevent erosion completely. Comparatively, graded stone-faced soil bunds revealed maximum desired impacts and were most appreciated by farmers, whereas level bunds caused water logging. Most traditional ditches were highly graded and begun incising and affected production of cereals. Despite the semi-quantitative nature of the methodology, using farmers' perceptions and experiences to document land degradation and the impacts of SWC measures is crucial as they are the daily users of the land and therefore directly affecting the success or failure of SWC measures.