Monitoring landscape restoration efforts and associated livelihood benefits for smallholder farmers in the Upper Tana Basin of Kenya

The Upper Tana Basin is an area that is very prone to soil erosion. In this study, we worked closely with 10 farmers in the Upper Tana Basin who were implementing a range of different land management options, specifically soil water conservation with terraces and forage grass strips. We installed and monitored erosion and runoff detectors in the farming landscapes to quantify how much soil was running off the surface. We compared how different land management practices if used in combination reduce soil erosion and result in livelihood benefits. The control areas that did not have SLM options showed substantial differences when compared to the areas with SLM within the different micro-watersheds over time and space. The farms without SLM produced less food but consumed most of their food produce and barely had any surplus to sell. For all micro-watersheds, SLM consistently consumed less food than the food produce they sold. This aspect has implications on the livelihood options of farmers. The interventions with SLM offered viable livelihood options for farmers while at the same time meeting their food security and nutritional needs compared to those without SLM that lacked the purchasing power due to lower market sales of their produce

Water yield estimation and sedimentation control in two Volta sub-basins: tools towards integrated water resources management

Small reservoirs form a major source of water supply in the Volta basin. However, sedimentation of reservoirs poses serious threats to overall water yield and storage, consequently impacting community water supplies and livelihoods. This study will assess basin-level water yields and sediment inflow deposited in reservoirs in two Volta sub-basins using the WEAP and SWAT models in combination with spatial analysis techniques. The WEAP Model will assess water allocations while the SWAT model will compute water balance, runoff and sediment yields. Ancillary measured sediment yield data will be used in combination with terrain-based distributed models in a GIS to identify and predict major areas of erosion in the two study sites. Social and biophysical dynamics will be concomittantly assessed through a multi-agent modeling framework (ComMod). To this end, the WEAP and SWAT models will be linked to the computer simulation tool of the ComMod platform. This will allow for assessing the consequences of local practices -and possibly proposed intervention- in terms of erosion (see figure). The results and the approach can be used as decision-support tools to identify practical IWRM interventions that reduce erosion e.g. vegetation strip-ways. It is anticipated that this will result in improved water resources management and reduce impacts of drought spell shocks on the affected communities and could be replicated elsewhere in the Volta basin. (Texte intégral

Hydrological consequences of two native shrubs in semi-arid Senegal : patterns, processes, concepts and methods

Water availability is a critical limiting element in semi-arid ecosystem productivity and presents particular challenges in Sahelian countries such as Senegal. The landscapes are characterized by the presence of two common semi-arid shrubs (Piliostigma reticulatum and Guiera senegalensis), both of which may be important hydraulic regulators in these water-limited ecosystems. Dry season observations revealed higher moisture levels in soil surrounding the shrub shallower roots relative to bare soil. This observation led us to hypothesize that these shrubs may participate in a natural irrigation phenomenon termed as "hydraulic redistribution" (HR). This dissertation reports on three studies performed to ascertain the existence of and investigate the characteristics of this hypothesized phenomenon. The first study investigated seasonal variability in soil water and shrub root patterns. Soil moisture content declined steadily in the 0.9-1.2 m depth range and increased in the 0.2-0.4 m depth range, which supports the HR hypothesis. The second study quantified plot scale water balance fluxes. Notably, shrub water uptake from the water table served as a crucial contribution to the system water balance. The third study investigated the magnitude and dynamics of HR during the dry season. Crop-shrub associations were evaluated from measurements of soil moisture and potential, root sap flow and plant physiological measurements. This study proved the existence of HR and quantified the HR magnitude (~0.1 mm d⁻¹). For shrubs and annual crops in close association with shrubs, HR clearly provides a mechanism for drought-stress avoidance and maintenance of plant physiological functions. At the landscape scale, the interplay between shrub root morphology and HR may play a vital role in ecosystem function with practical implications for nutrient cycling and water balance in arid ecosystems

Landscape natural resources management with soil and water conservation practices

United States Agency for International Developmen

The indirect impact of crop insurance on household food security in the Guinea savannah region of West Africa

Under high climatic, disease and market uncertainty, smallholder farmers make heuristic decisions on whether to manage risk and invest in profitable alternatives or, as a risk-averse mechanism, continue with the traditional low-risk low-return practices. The goal of this paper is to investigate the role of information, social capital, and resource endowments on farmers' decision to invest in insurance bundled with fertilizer and modern improved seeds and its impacts on food security indicators including surplus produce, marketing share, and produce storage. Results show that insurance induces a 113% increase in the proportion of maize sold and an increased probability to keep food reserves for the lean period by 42%. Impacts of insurance on marketing and storage are contingent on cropping system, agro-advisory and resource endowments with differentiated effects. These findings reveal that bundling crop insurance with high-cost productivity improving inorganic fertilizers and modern improved varieties bred for drought tolerance is a viable option for farmers to make risky productivity-enhancing investments and improve livelihoods that contribute economic development and food security