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ACKNOWLEDGEMENTS -- TABLE OF CONTENTS -- LIST OF ABBREVIATIONS -- CHAPTER 1GENERAL INTRODUCTION -- CHAPTER 2REDISTRIBUTION OF CARBON AND NITROGEN THROUGHIRRIGATION IN INTENSIVLY CULTIVATED TROPICALMOUNTAINOUS WATERSHEDSDieses Werk -- CHAPTER 3SEDIMENT INDUCED SOIL SPATIAL VARIATION IN PADDY FIELDSOF NORTHWEST VIETNAMDieses Werk -- CHAPTER 4LINKING SPATIO-TEMPORAL VARIATION OF CROPPERFORMANCE WIDTH SEDIMENT DEPOSITION ALONG PADDYRICE TERRACESDieses -- CHAPTER 5WHY DO PEOPLE NOT LEARN FROM FLOOD DISASTERS?EVIDENCE FROM VIETNAM'S NORTHWESTERN MOUNTAINSDieses Werk -- CHAPTER 6GENERAL DISCUSSIONDieses -- CHAPTER 7SUMMARYDieses -- Zusammenfassung -- CHAPTER 8REFERENCESDieses

Smallholder irrigation expansion would significantly increase agricultural production, and reduce food insecurity and poverty levels in East Africa. This paper reviews literature on trends, constraints and opportunities of smallholder irrigation in four East African countries: Ethiopia, Kenya, Tanzania and Uganda. Irrigation development has been slow in these countries, and has been mainly through traditional schemes. Recently, individual irrigation technologies such as small motorized pumps, drip kits, treadle pumps, rope and washer pumps are being promoted. Adoption of these technologies and expansion of smallholder irrigation however face a number of challenges including land tenure issues; lack of access to appropriate irrigation technologies, improved agricultural inputs, reliable markets, finance and credit services, and research support; poor transport and communication infrastructures; poor irrigation water management; poor extension systems; and the over dependence on national governments, NGOs and donors for support. Despite these challenges, opportunities exist for smallholder irrigation expansion in East Africa. Such opportunities include: high untapped irrigation potential; rainwater harvesting to improve water availability; high commitment of national governments, NGOs and donors to smallholder irrigation expansion; low cost irrigation technologies adaptable to local conditions; traditional schemes rehabilitation; growing urbanization; and increased use of mobile phones that can be used to disseminate information.

Agricultural innovation scaling approaches tend to be empirical but do not sufficiently take into account the complex realities of 'softer elements' such as people, supply chains, markets, financing mechanisms, policies and regulations, professional knowledge, power relations, incentives and history. As a consequence, scaling initiatives often do not produce the desired impacts and, in some instances, may even produce undesirable impacts. |Designing scaling strategies that are adaptive to context and available resources requires an understanding of the enabling environment in which the scaling processes are embedded. This can be achieved by conducting an analysis to identify enablers and hinderers influencing farmers' adoption of irrigation and water management technologies and introducing measures to ensure success. The tool described in this working paper provides implementers with a structured guide to carrying out this analysis in a specific context.

In recent years, farmer-led irrigation development has gained the interest of development partners and governments in the Global South following its success in enhancing agricultural production and livelihoods in South Asia. However, little is known about the socio-economic situation of farmers who receive public support for its expansion. Considering its rapid expansion in sub-Saharan Africa, we take the case of Ethiopia and explore the relationship between irrigation suitability and farmers' socio-economic status. We find that high-value crop producers and wealthier farmers are most likely to make private investments and also benefit from public support in farmer-led irrigation expansion if investments are directed to land areas highly suitable for irrigation. Cultivation of high-value crops (fruit, vegetables) was common in areas more suitable for irrigation but staple crop cultivation (cereals, legumes) was negatively associated with irrigation suitability. Wealth status (consumption expenditure, asset index, and land size) was also positively correlated with irrigation suitability. A 10 per cent increase in groundwater irrigation suitability score was associated with a 2 per cent increase in per-capita consumption expenditure. Results imply that policies aiming to facilitate farmer-led irrigation development should combine biophysical information on land and water suitability for irrigation with household socio-economic characteristics and existing agricultural systems.

The Ethiopian government has declared the Lake Tana - Beles region to be a growth corridor and irrigation development is one of the priorities. Since the dry season river flow is limited, groundwater has the greatest potential for increasing irrigation in the near future. The main drawback is lack of information on sustainable groundwater use and specifically the ground water potential. Therefore the objective of this research is to calculate the annual groundwater recharge. The study was conducted in Robit-Bata, an experimental watershed of 911 ha, located at the south-eastern edge of Lake Tana. Farmers have excavated more than 300 hand dug wells for irrigation use from which, we used 50 wells for water table fluctuation observations for one year starting from April, 2014. Daily Precipitation was recorded for the same period. The annual recharge was estimated using the water – level fluctuation method. Specific yield was defined as the difference of porosity and field capacity of the subsurface formation. The annual average areal groundwater recharge was 640 mm/year, which is 41% of the rainfall and ranged from 50mm to 390mm per week for the various locations in the watershed. The greatest recharge amounts were found in the plains at the foot of the hills and river course areas consisting mostly weathered basalt rock. At those locations the groundwater rose steadily during the rainy monsoon phase. Smaller amount of recharge occurred both near the top of the hills with tough rock formation and in the, flat areas near to stream with sandy and clay deposits and groundwater at, shallow well depth. Our study indicates that the current use of the groundwater seems sustainable. Further research is required for optimized utilization of the limited groundwater resources for irrigation development to meet the food security of the community.