Robyn Johnston

Water Resource Models in the Mekong Basin: A Review

Development of the water resources of the Mekong Basin is the subject of intense debate both within the Mekong region and internationally. Water resources modelling is playing an increasingly important role in the debate, with significant effort in building integrated modelling platforms to describe the hydrological, ecological, social and economic impacts of water resource development. In the hydrological domain, a comprehensive set of models has been effective in building understanding of the system, and in identifying and describing the issues and trade-offs involved in basin-scale water planning. In the ecological and social domains, quantitative modelling has not progressed very far; geo-spatial analysis and qualitative frameworks remain the most commonly used tools. Economic models have been used to assess the costs and benefits of water resources development and to describe the trade-offs between different sectors and users. These analyses are likely to play an important role in the policy and planning debate, but are hampered by uncertainties in valuation of ecosystem services. Future efforts should focus on optimising the use of existing model platforms for the Mekong, including structured comparison of multiple hydrological models to quantify errors and identify an optimum set of modelling tools for different applications. A comprehensive research effort is needed to incorporate groundwater into hydrological models for regional planning. Options for social impact assessment should be reassessed before major investments are made in complex modelling platforms, and participatory social survey methods evaluated as part of an integrated assessment framework.

Hydrological Modeling of Large river Basins: How Much is Enough?

Hydrological modeling is an indispensable component of water resources research and management in large river basins. There is a tendency for each new group working in a basin to develop their own model, resulting in a plethora of such tools for each major basin. The question then becomes: how much modeling is enough? This study reviews hydrological modeling in four large basins (Nile, Mekong, Ganges and Indus). Based on this review, four areas for action to improve effectiveness and reduce duplication in hydrological modeling of large basins are suggested. Model setups and input data, as well as model results, should be published, to allow more coordinated approaches and capitalize on past modeling efforts. More focus is needed on reporting uncertainty, to allow more realistic assessment of the degree of confidence in using results for policy and management. Initiatives are needed to improve the quantity and quality of data for model input, calibration and validation, both traditional hydrological monitoring (improved networks, expansion of automated systems) and new methods for data collection (remote sensing, crowd-sourcing and community based observations). Finally, within each major basin, an appropriate agency should be identified and resourced to take responsibility for data sharing and coordination, to reduce redundancy of effort and promote collaboration.

Understanding determinants of farmers’ investments in sustainable land management practices in Ethiopia: review and synthesis

Although there has been several efforts made to reduce land degradation and improve land productivity in Ethiopia, farmers’ investments in sustainable land management (SLM) remain limited. Nevertheless, the results regarding determinants of farmers’ investments in SLM have been inconsistent and scattered. Moreover, these factors have not been reviewed and synthesized. Hence this paper reviews and synthesizes past research in order to identify determinants that affect farmers’ investments in SLM practices and thereby facilitate policy prescriptions to enhance adoption in Ethiopia, East Africa and potentially wider afield. The review identifies several determinants that affect farmers’ investments in SLM practices. These determinants are generally categorized into three groups. The first group is those factors that are related to farmers’ capacity to invest in SLM practices. The results show that farmers’ investments in SLM practices are limited by their limited capacity to invest in SLM. The second groups of factors are related to farmers’ incentives for investments in SLM practices. Farmers’ investments in SLM are limited due to restricted incentives from their investments related to land improvement. The third groups of factors are external factors beyond the control of farmers. The review also shows that farmers’ capacities to invest in SLM and their incentives from investments have been influenced by external factors such as institutional support and policies. This suggests that creating enabling conditions for enhancing farmers’ investment capacities in SLM and increasing the range of incentives from their investment is crucial to encourage wide-scale adoption of SLM practices.

Restoring aboveground carbon and biodiversity: a case study from the Nile basin, Ethiopia.

In Ethiopia, exclosures in landscapes have become increasingly important to improving ecosystem services and reversing biodiversity losses. The present study was conducted in Gomit watershed, northern Ethiopia, to: (i) investigate the changes in vegetation composition, diversity and aboveground biomass and carbon following the establishment of exclosures; and (ii) analyse the economic returns of aboveground carbon sequestration and assess the perception of local communities on land degradation and exclosures. A space-for-time substitution approach was used to detect the changes in aboveground carbon, species composition, and diversity. Exclosures of 1-, 2-, 3-, 4-, 5-, and 7-years-old and a communal grazing land were selected. Household surveys, key informant interviews, and a financial analysis were used to assess the perception of local communities and the value of exclosure impacts, respectively. Significant (P = 0.049) differences in species diversity and considerable increases in aboveground carbon (ranged from 0.6 to 4.2 t C ha−1), CO2 storage (varied between 2.1 and 15.3 t CO2 ha−1), woody species composition, and richness (ranged from five to 28) were observed following the establishment of exclosures. Exclosures generated temporary certified emission reductions (tCER) of 3.4, 2.1, 7.5, 12.6, 12.5, and 15.3 Mg CO2 ha−1 after 1, 2, 3, 4, 5, and 7 years, respectively. The net present value (NPV) of the aboveground carbon sequestered in exclosures ranged from US

Towards decision support-based integrated management planning of papyrus wetlands: a case study from Uganda

6.6 to US

Impacts of Soil and Water Conservation Practices on Crop Yield, Run-off, Soil Loss and Nutrient Loss in Ethiopia: Review and Synthesis.

37.0 per hectare and increased with exclosure duration. At a watershed level, 51.4 Mg C ha−1 can be sequestered, which represents 188.6 Mg CO2 ha−1, resulting in tCER of 139.4 Mg CO2 ha−1 and NPV of US

Tackling change: future-proofing water, agriculture, and food security in an era of climate uncertainty

478.3 per hectare. This result would suggest that exclosures can potentially improve local communities’ livelihoods beyond rehabilitating degraded lands if carbon stored in exclosures is traded. Communities in the watershed demonstrated that exclosures are effective in restoring degraded lands and they are benefiting from increased fodder production and reduced impacts of soil erosion. However, the respondents are also concerned over the sustainability of exclosure land management, as further expansion of exclosures aggravates degradation of remaining communal grazing lands and causes fuel wood shortages. This suggests that the sustainability of exclosure land management can be attained only if these critical concerns are addressed by a joint effort among government agencies, nongovernmental organizations, and communities.

Groundwater Resources in the Dry Zone of Myanmar: A Review of Current Knowledge

Management and decision making for wetlands need an integrated approach, in which all ecosystem services are identified, their importance are assessed and objectives are formulated about their desired outputs. This approach has been applied successfully in European wetlands with sufficient scientific data. The main objective of this study was to evaluate the application of this approach in the context of a data-poor, multi-use African wetland. The Namatala wetland in Uganda, a wetland under intense pressure from wastewater discharge, conversion to agriculture and vegetation harvesting, was used as a case study. After characterisation of the wetland ecosystem and stakeholder analysis, three management options, subdivided into 13 sub-options, were identified for the wetland. These options were combined into six management solutions. A set of 15 indicators, subdivided into five categories (livelihood; human health; ecology; costs; risk of failure), were identified to assess the performance of these management solutions. Stakeholders’ preferences were taken into consideration by means of weights attached to the indicators, and a best-compromise solution was derived which consisted of a combination of sustainable agriculture in the upper Namatala wetland, papyrus buffer strips along the Namatala river channel, sustainable land use (vegetation harvesting, fishing) in lower Namatala wetland, and papyrus buffer zones at the waste-water discharge points. Despite differences of opinion among stakeholder groups about the relative importance of the indicators, the same compromise solution resulted for all stakeholders. It was concluded that this systematic approach and the stakeholder dialogue about the management options were beneficial to the management process, although the approach would benefit from more and better data about the wetland system and from model-derived predictions.

Hydrological models bring clarity and consensus to challenging policy issues

Research results published regarding the impact of soil and water conservation practices in the highland areas of Ethiopia have been inconsistent and scattered. In this paper, a detailed review and synthesis is reported that was conducted to identify the impacts of soil and water conservation practices on crop yield, surface run-off, soil loss, nutrient loss, and the economic viability, as well as to discuss the implications for an integrated approach and ecosystem services. The review and synthesis showed that most physical soil and water conservation practices such as soil bunds and stone bunds were very effective in reducing run-off, soil erosion and nutrient depletion. Despite these positive impacts on these services, the impact of physical soil and water conservation practices on crop yield was negative mainly due to the reduction of effective cultivable area by soil/stone bunds. In contrast, most agronomic soil and water conservation practices increase crop yield and reduce run-off and soil losses. This implies that integrating physical soil and water conservation practices with agronomic soil and water conservation practices are essential to increase both provisioning and regulating ecosystem services. Additionally, effective use of unutilized land (the area occupied by bunds) by planting multipurpose grasses and trees on the bunds may offset the yield lost due to a reduction in planting area. If high value grasses and trees can be grown on this land, farmers can harvest fodder for animals or fuel wood, both in scarce supply in Ethiopia. Growing of these grasses and trees can also help the stability of the bunds and reduce maintenance cost. Economic feasibility analysis also showed that, soil and water conservation practices became economically more viable if physical and agronomic soil and water conservation practices are integrated.

Rethinking agriculture in the Greater Mekong Subregion: how to sustainably meet food needs, enhance ecosystem services and cope with climate change

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