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Poverty is multi-dimensional global challenge that impedes individual and community capacities to satisfy basic needs. These capacities are shaped by locally configured institutional and biophysical processes that are often hidden from external researchers and practitioners. To explore this worldwide aspect, we adopt participatory rural appraisal (PRA) methods to expose barriers to implementing livelihood strategies to address poverty in Ethiopia's upper Blue Nile basin, where 85 % of the population are subsistence farmers reliant on local ecosystem services (ES). We identify local barriers to poverty alleviation in three steps. First, we classify major ES-livelihood interrelationships among communities of Debre Mawi catchment in upper Blue Nile. Secondly we assess ongoing struggles in these interrelations using combined biophysical and social assessment criteria to evaluate how poverty relates to current patterns of ES management. The analysis identifies complex interdependencies between livelihoods and regulating (crop pest controls), provisioning (water, land, and feed availability, soil fertility) and cultural (top-down ES management, population growth) ES that create bottlenecks to effectively 'lock in' poverty. Thirdly, we identify potential new ES management strategies, focused on dry season water availability. We conduct participatory field experiments on rooftop water harvesting to show this is a promising approach for increasing water availability to enhance agricultural production. Depending on the rooftop area, our modelling suggests that farmers can improve household income by US$136– 14,876 from 5 months beef fattening and US$69–7704 from 4 months sheep fattening. Except these specific livelihood strategies, the findings are replicable to the world's ES-dependent regions. • A novel rigorous approach was developed to maximize poverty alleviation. • Water scarcity is most important bottleneck to move out of poverty. • Rooftop water harvesting avoids water scarcity and improves livelihood. • Unpredictable rainfall causes significant crop yield reduction. • Poverty alleviation needs to focus on the poorest segment of society. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2010.03.019 Byline: Joshua W. Faulkner, Zachary M. Easton, Wei Zhang, Larry D. Geohring, Tammo S. Steenhuis Abstract: Vegetative treatment areas (VTAs) are commonly being used as an alternative method of agricultural process wastewater treatment. However, it is also apparent that to completely prevent discharge of pollutants to the surrounding environment, settling of particulates and bound constituents from overland flow through VTAs is not sufficient. For effective remediation of dissolved agricultural pollutants, VTAs must infiltrate incoming wastewater. A simple water balance model for predicting VTA soil saturation and surface discharge in landscapes characterized by sloping terrain and a shallow restrictive layer is presented and discussed. The model accounts for the cumulative effect of successive rainfall events and wastewater input on soil moisture status and depth to water table. Nash-Sutcliffe efficiencies ranged from 0.65 to 0.81 for modeled and observed water table elevations after calibration of saturated hydraulic conductivity. Precipitation data from relatively low, average, and high annual rainfall years were used with soil, site, and contributing area data from an example VTA for simulations and comparisons. Model sensitivity to VTA width and contributing area (i.e. barnyard, feedlot, silage bunker, etc.) curve number was also investigated. Results of this analysis indicate that VTAs should be located on steeper slopes with deeper, more-permeable soils, which effectively lowers the shallow water table. In sloping landscapes (>2%), this model provides practitioners an easy-to-use VTA design and/or risk assessment tool that is more hydrological process-based than current methods. Author Affiliation: Department of Biological and Environmental Engineering, Cornell University, 62 Riley-Robb Hall, Ithaca, NY 14850, USA Article History: Received 16 September 2009; Revised 16 March 2010; Accepted 27 March 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2008.08.011 Byline: Nalini S. Rao (a)(b), Zachary M. Easton (a), Elliot M. Schneiderman (c), Mark S. Zion (c), David R. Lee (d), Tammo S. Steenhuis (a) Abbreviations: Best Management Practices, BMP; Dissolved Phosphorus, DP; Particulate Phosphorus, PP; Total Phosphorus, TP; Variable Source Areas, VSAs Abstract: Planners advocate best management practices (BMPs) to reduce loss of sediment and nutrients in agricultural areas. However, the scientific community lacks tools that use readily available data to investigate the relationships between BMPs and their spatial locations and water quality. In rural, humid regions where runoff is associated with saturation-excess processes from variable source areas (VSAs), BMPs are potentially most effective when they are located in areas that produce the majority of the runoff. Thus, two critical elements necessary to predict the water quality impact of BMPs include correct identification of VSAs and accurate predictions of nutrient reduction due to particular BMPs. The objective of this research was to determine the effectiveness of BMPs using the Variable Source Loading Function (VSLF) model, which captures the spatial and temporal evolutions of VSAs in the landscape. Data from a long-term monitoring campaign on a 164-ha farm in the New York City source watersheds in the Catskills Mountains of New York state were used to evaluate the effectiveness of a range of BMPs. The data spanned an 11-year period over which a suite of BMPs, including a nutrient management plan, riparian buffers, filter strips and fencing, was installed to reduce phosphorus (P) loading. Despite its simplicity, VSLF predicted the spatial distribution of runoff producing areas well. Dissolved P reductions were simulated well by using calibrated reduction factors for various BMPs in the VSLF model. Total P losses decreased only after cattle crossings were installed in the creek. The results demonstrated that BMPs, when sited with respect to VSAs, reduce P loss from agricultural watersheds, providing useful information for targeted water quality management. Author Affiliation: (a) Department of Biological and Environmental Engineering, 206 Riley-Robb Hall, Cornell University, Ithaca, NY 14853, United States (b) Department of Natural Resources, Fernow Hall, Cornell University, Ithaca, NY 14853, United States (c) New York City Department of Environmental Protection, Kingston, NY 12401, United States (d) Department of Applied Economics and Management, Warren Hall, Cornell University, Ithaca, NY 14853, United States Article History: Received 22 August 2007; Revised 31 July 2008; Accepted 24 August 2008

Gullies that are expanding at alarming rate are responsible for the majority of soil losses in the (sub) humid highlands of Ethiopia. Few affordable and effective methods for gully erosion control are available in the highlands. The objective of the study was to develop cost-effective measures to halt gully expansion by determining stable-bank conditions under a variety of environmental situations using the Bank Stability and Toe Erosion Model (BSTEM). The study was carried out in the sub humid Debre Mawi watershed, located 30 km south of Lake Tana. Input data for the BSTEM model were collected using field surveys and soil sampling. After the BSTEM was tested on actual measured soil data, soil cohesion and internal friction angle were calibrated against observed gully bank retreat. Using the calibrated parameters, the model evaluated the stabilization of the existing gully bank under different scenarios in which groundwater table, bank angle and bank height, tension crack depth, vegetation, and toe protection were varied. Finally, the head-cut of the study gully was treated based on the model recommendation. The simulated results showed that a 5 m deep gully was stable under fully saturated conditions when the bank toe is protected, its upper surface is vegetated, and its bank angles do not exceed 45°. If the depth of the gully is less than 5 m or if its water table is deeper than 0.5 m, only regrading the gully bank to an angle of 45° can stabilize the gully. BSTEM showed to be an effective tool that can be used to evaluate gully control measures. [ABSTRACT FROM AUTHOR]

Abstract Soil degradation and associated soil erosion is a daunting socio-economic challenge for smallholder farmers that cause environmental harm in the developing regions of the world. This is especially true in the Ethiopian highlands where soil degradation and soil erosion significantly impact the productivity of land and water. In this study, GIS-based classic RUSLE model supported with multi-criteria evaluation (MCE) analysis was used to map erosion hotspot areas in the sub-humid Ethiopian highlands. RUSLE model results indicated that annual average soil loss in the study area reaches up to 288 t ha−1. In the majority (83%) of the study area predicted soil loss ranges between 0 and 40 t ha−1, whereas 13% of the study area has soil loss of 40–100 t ha−1 and the remaining 4% is in excess of 100 t ha−1. Seventy-two percent of upper Gilgel Abbay watershed was found moderately sensitive to erosion. The classic RUSLE predicted lower erosion rates mainly in the bottomlands because does not consider soil erosion by gullies. On the other hand, the MCE analysis integrated with field survey indicated that the potential location of gullies is the saturated bottomlands. The locations of bottomland gullies also coincided with important hydrologic parameters such as higher soil wetness and stream power index values. The implication is that in addition to RUSLE criteria such as gullies, topographic wetness index (TWI) and stream power index (SPI) should be considered in erosion risk mapping studies in the sub-humid Ethiopian highlands, where soil saturation plays an important role in the formation and expansion of gullies. [ABSTRACT FROM AUTHOR]

Land use and management affects runoff and soil loss from a catchment. The present study investigated the effects of land use on runoff and suspended sediment concentration and yield in the northwestern Ethiopia. We selected two small catchments: cultivated land and grassland dominated catchments within the 95 ha Debre Mawi catchment. Hydrometric and sediment concentration data were collected for five years (i.e., 2010–2014). Significant ( p < 0.05) differences in daily, monthly and annual runoff, as well as suspended sediment concentrations were observed between cultivated land and grassland dominated catchments. The greater runoff, suspended sediment concentration and yield in the cultivated catchment could be attributed to repeated tillage and low soil organic matter. Repeated tillage in the cultivated land lead to soil disturbance and the low organic matter lead to aggregate instability, both of which consequently increase the detachment of soil particles and transport by generated runoff. Our results support that land management practices that involve lower soil disturbance and increase ground cover on degraded highland areas such as the Ethiopian highlands could help reduce runoff and soil loss. [ABSTRACT FROM AUTHOR]

Estimation of storage volume of inland water bodies is made using bathymetric surveys. Such surveys are often terminated far inward from shores due to operational limitations. The gap in depth data for the shore area is often overcome by extrapolating the established volume-area relationship beyond the survey boundary. This introduces large errors in volume estimation. In this study, the potential of the Moderate Resolution Imaging Spectroradiometer MODIS version-5 images to improve an existing bathymetric model is assessed over Lake Tana, Ethiopia. MODIS images are used to generate a new bathymetric model of the unsurveyed shore. The new model is validated through its ability to reproduce measured lake levels. The result is compared with lake level estimates made from an existing bathymetric survey. Results showed that MODIS improved bathymetric model reproduced lake water level with a RMSE of 0.14 m as compared to 0.82 m using the existing bathymetric model. The Mean Absolute Error (MAE) has also improved from 0.78 m to 0.13 m. These results suggest that despite their unavailability on cloudy days, MODIS images provide significant advantages for improving bathymetric models. [ABSTRACT FROM AUTHOR]

Excessive runoff and soil erosion in the upper Blue Nile Basin poses a threat that has attracted the attention of the Ethiopian government because of the serious on-site effects in addition to downstream effects, such as the siltation of water harvesting structures and reservoirs. The objective of the study was to evaluate and recommend effective biophysical soil and water conservation measure(s) in the Debre Mewi watershed, about 30 km south of the Lake Tana. Six conservation measures were evaluated for their effects on runoff, soil loss, and forage yield using runoff plots. There was a significant difference between treatments for both runoff and soil loss. The four-year average annual soil loss in the different plots ranged from 26 to 71 t ha −1 , and total runoff ranged from 180 to 302 mm, while annual rainfall varied between 854 mm in 2008 and 1247 mm in 2011. Soil bund combined with elephant grass had the lowest runoff and soil loss as compared to the other treatments, whereas the untreated control plot had the highest for both parameters. As an additional benefit, 2.8 and 0.7 t ha −1 year −1 of dried forage was obtained from elephant and local grasses, respectively. Furthermore, it was found that soil bund combined with Tephrosia increased soil organic matter by 13% compared to the control plot. Soil bund efficiency was significantly enhanced by combining them with biological measures and improved farmers’ perception of soil and water conservation measures. [ABSTRACT FROM AUTHOR]

Abstract: During the last 25 years there has been a great interest in deriving aquifer characteristics from outflow data. This analysis has been mainly based of the drainage of a horizontal aquifer after sudden drawdown, using the Boussinesq approximation. Following the general approach of Brutsaert and Lopez [Brutsaert W, Lopez, JP. Basin-scale geohydrologic drought flow features of riparian aquifers in the southern Great Plains. Water Resour Res 1998;34(2):233–40], it was determined that for this geometry the aquifer behavior could be characterized by dQ/dt ∝ Q 3 for small t and by dQ/dt ∝ Q 3/2 for large t. It was remarked that dQ/dt ∝ Q for large t is often observed. In practice, it is also difficult to determine if dQ/dt ∝ Q 3 for small t because this behavior can only be observed over a very short period. Here, we present a similar analysis of aquifer behavior based on the more fundamental Laplace solution for penetrated aquifers. It has been shown that also when the drain does not fully penetrate the aquifer, the solution still produces good results [Szilagyi, J. Sensitivity analysis of aquifer parameter estimations based on the Laplace equation with linearized boundary conditions. Water Resour Res 2003;39(6)]. The Laplace solution quickly shows that dQ/dt ∝ Q for t →∞ and dQ/dt ∝ Q ∞ for t →0, after sudden drawdown. This analysis reconfirms previous findings concerning long-time behavior. More importantly, the analysis shows that the exponent B in dQ/dt ∝ Q B does not have a fixed limited value for short times for the given geometry. Further analysis, however, shows that under certain conditions the relation dQ/dt ∝ Q 3 is retained for 0≪ t &#60;1. Detailed examination of the Laplace solution also shows under which types of recharge dynamics a well-identifiable transition takes place between short- and long-term behavior. As long as such a clear transition exists, the aquifer characterization method proposed earlier by Brutsaert and Lopez [Brutsaert W, Lopez, JP. Basin-scale geohydrologic drought flow features of riparian aquifers in the southern Great Plains. Water Resour Res 1998;34(2):233–40] can be applied. It is shown that for a sharp pulse input, the Laplace solution gives similar results as presented by Brutsaert and Lopez [Brutsaert W, Lopez, JP. Basin-scale geohydrologic drought flow features of riparian aquifers in the southern Great Plains. Water Resour Res 1998;34(2):233–40]. For a smooth pulse, the transition becomes unclear. What is “smooth” and “sharp” depends on input and aquifer characteristics, whereby shallow aquifers give clearer transitions than deep aquifers for the same input. The analysis shows that when rain ceases suddenly after the aquifer has come into equilibrium with a steady rain input, a usable transition in the relation between dQ/dt and Q can be found as well. Researchers can use the present analysis to assess whether specific aquifers and recharge events can be used for the previously suggested characterization method. [Copyright &y& Elsevier]

Abstract: In order to assess the reliability of the springs near Matalom, Leyte, Philippines as a sustainable source of drinking water, we measured precipitation and outflow of five small and two large springs for the region for a period of a year and analyzed the recession spring flow data. Although monthly spring flow follows a similar pattern to that of the rainfall, the regression relationship between both parameters is poor except for the smallest spring. To determine the dry season spring flow behavior, we analyzed the spring flow data with a mechanistic recession flow model originally developed for prediction of stream drought flow in the northeastern U.S. by Brutsaert and Nieber in 1977. The model describes the dry season spring flow well assuming that the aquifer behaves as a linear reservoir. The analysis shows that the flow “half-life” for the springs is about one month. By adding the individual spring flows to derive a watershed outflow we were able to evaluate how well the simple watershed geometry underlying the analysis of Brutsaert and Nieber [Regionalized drought flow hydrographs from a mature glaciated plateau. Water Resour Res 1977;13(3):637–43] applies to the more complex watersheds. [Copyright &y& Elsevier]

Leaching of sludge-borne trace elements has been observed in experimental and field studies. The role of microbial processes in the mobilization of trace elements from wastewater sludge is poorly defined. Our objectives were to determine trace element mobilization from sludge subjected to treatments representing microbial acidification, direct chemical acidification and no acidification, and to determine the readsorption potential of mobilized elements using calcareous sand. Triplicate columns (10-cm diameter) for incubation and leaching of sludge had a top layer of digested dewatered sludge (either untreated, acidified with H2SO4, or limed with CaCO3; all mixed with glass beads to prevent ponding) and a lower glass bead support bed. Glass beads in the sludge layer, support layer or both were replaced by calcareous sand in four treatments used for testing the readsorption potential of mobilized elements. Eight sequential 8-day incubation and leaching cycles were operated, each consisting of 7.6 d of incubation at 28 °C followed by 8 h of leaching with synthetic acid rain applied at 0.25 cm/h. Leachates were analyzed for trace elements, nitrate and pH, and sludge layer microbial respiration was measured. The largest trace element, nitrate and S losses occurred in treatments with the greatest pH depression and greatest microbial respiration rates. Cumulative leaching losses from both microbial acidification and direct acidification treatments were >90% of Zn and 64–80% of Cu and Ni. Preventing acidification with sludge layer lime or sand restricted leaching for all trace elements except Mo. Results suggested that the primary microbial role in the rapid leaching of trace elements was acidification, with results from direct acidification being nearly identical to microbial acidification. Microbial activity in the presence of materials that prevented acidification mobilized far lower concentrations of trace elements, with the exception of Mo. Trace elements mobilized by acidification were readsorbed by calcareous sand when present. [Copyright &y& Elsevier]

Minasny et al. (2020) proposed enhancing future global soil science research by examining the role of soils in global ecosystem functioning. They argued in particular that meaningful collaboration between high- and low-income countries is essential to generate new knowledge and facilitate capacity building. In this commentary, we provide an account of our experience with an effective cooperative research and training partnership between Cornell University and Bahir Dar University in Ethiopia. We note that, in addition to the willingness and commitment of the scientists to cooperate, support and flexibility of senior university administrators is essential for international cooperation to succeed. We illustrate these points describing our experience and show that these cooperative efforts are evolving incrementally and in many cases do not follow well-laid-out programs. [ABSTRACT FROM AUTHOR]

Soil and water conservation structures, promoted by local and international development organizations throughout rural landscapes, aim to increase recharge and prevent degradation of soil surface characteristics. This study investigates this unexamined relationship between recharge, water table depths, and soil surface characteristics (nutrients) in a small sub-watershed in the northwestern Ethiopian highlands. These highland watersheds have high infiltration rates (mean 70 mm hr −1 , median 33 mm hr −1 ), recharging the shallow unconfined hillslope aquifer with water transport occurring via subsurface pathways down the slope. The perched water tables reflect the subsurface flux and are deep where this flux is rapid in the upland areas (138 cm below surface). Soil saturation and overland flow occur when the subsurface flux exceeds the transport capacity of the soil in the lower downslope areas near the ephemeral stream (19 cm below surface). Land use is directly related to the water table depth, corresponding to grazing and fallowed (saturated) land in the downslope areas and cultivated (unsaturated) land in the middle and upper parts where the water table is deeper. Kjeldahl Total Nitrogen (TN), Bray II available phosphorus (AP), and exchangeable potassium (K + ) averages exhibit different behaviors across slope, land use transects, or saturation conditions. TN was moderate to low (0.07% ± 0.04) in various land uses and slope regions. Bray II AP had very low concentrations (0.25 mg kg −1  ± 0.26) among the different slope regions with no significant differences throughout (p > .05). The exchangeable cation (K + , Ca 2+ , Mg 2+ ) concentrations and pH, however, were greater in non-cultivated (seasonally saturated) lands and in a downslope direction (p < .001, p < .005, p < .05, and p < .005, respectively). These results show that the perched groundwater plays an important role in influencing land use, the amount of water seasonally available for crop growth, and exchangeable cations, but have no clear effect on the concentration of the two primarily applied nutrients in fertilizers (N, P). [ABSTRACT FROM AUTHOR]