Definitions and Mapping of East African Wetlands: A Review <s> characterized them as "…among (Kenya's) most important resources for social-cultural and economic development." <s> To conserve and manage wetland resources, it is important to inventoryand monitor wetlands and their adjacent uplands. Satellite remote sensing hasseveral advantages for monitoring wetland resources, especially for largegeographic areas. This review summarizes the literature on satellite remotesensing of wetlands, including what classification techniques were mostsuccessful in identifying wetlands and separating them from other land covertypes. All types of wetlands have been studied with satellite remote sensing.Landsat MSS, Landsat TM, and SPOT are the major satellite systems that have beenused to study wetlands; other systems are NOAA AVHRR, IRS-1B LISS-II and radarsystems, including JERS-1, ERS-1 and RADARSAT. Early work with satellite imageryused visual interpretation for classification. The most commonly used computerclassification method to map wetlands is unsupervised classification orclustering. Maximum likelihood is the most common supervised classificationmethod. Wetland classification is difficult because of spectral confusion withother landcover classes and among different types of wetlands. However,multi-temporal data usually improves the classification of wetlands, as doesancillary data such as soil data, elevation or topography data. Classifiedsatellite imagery and maps derived from aerial photography have been comparedwith the conclusion that they offer different but complimentary information.Change detection studies have taken advantage of the repeat coverage andarchival data available with satellite remote sensing. Detailed wetland maps canbe updated using satellite imagery. Given the spatial resolution of satelliteremote sensing systems, fuzzy classification, subpixel classification, spectralmixture analysis, and mixtures estimation may provide more detailed informationon wetlands. A layered, hybrid or rule-based approach may give better resultsthan more traditional methods. The combination of radar and optical data providethe most promise for improving wetland classification. <s> BIB001 </s> Definitions and Mapping of East African Wetlands: A Review <s> characterized them as "…among (Kenya's) most important resources for social-cultural and economic development." <s> The Wetlands and Water synthesis was designed for the Ramsar Convention to meet the need for information about the consequences of ecosystem change for human well-being and sought to strengthen the link between scientific knowledge and decision-making for the conservation and wise use of wetlands. <s> BIB002 </s> Definitions and Mapping of East African Wetlands: A Review <s> characterized them as "…among (Kenya's) most important resources for social-cultural and economic development." <s> [1] Surface fresh water is essential for life, yet we have surprisingly poor knowledge of the spatial and temporal dynamics of surface freshwater discharge and changes in storage globally. For example, we are unable to answer such basic questions as “What is the spatial and temporal variability of water stored on and near the surface of all continents?” Furthermore, key societal issues, such as the susceptibility of life to flood hazards, cannot be answered with the current global, in situ networks designed to observe river discharge at points but not flood events. The measurements required to answer these hydrologic questions are surface water area, the elevation of the water surface (h), its slope (∂h/∂x), and temporal change (∂h/∂t). Advances in remote sensing hydrology, particularly over the past 10 years and even more recently, have demonstrated that these hydraulic variables can be measured reliably from orbiting platforms. Measurements of inundated area have been used to varying degrees of accuracy as proxies for discharge but are successful only when in situ data are available for calibration; they fail to indicate the dynamic topography of water surfaces. Radar altimeters have a rich, multidecadal history of successfully measuring elevations of the ocean surface and are now also accepted as capable tools for measuring h along orbital profiles crossing freshwater bodies. However, altimeters are profiling tools, which, because of their orbital spacings, miss too many freshwater bodies to be useful hydrologically. High spatial resolution images of ∂h/∂t have been observed with interferometric synthetic aperture radar, but the method requires emergent vegetation to scatter radar pulses back to the receiving antenna. Essentially, existing spaceborne methods have been used to measure components of surface water hydraulics, but none of the technologies can singularly supply the water volume and hydraulic measurements that are needed to accurately model the water cycle and to guide water management practices. Instead, a combined imaging and elevation-measuring approach is ideal as demonstrated by the Shuttle Radar Topography Mission (SRTM), which collected images of h at a high spatial resolution (∼90 m) thus permitting the calculation of ∂h/∂x. We suggest that a future satellite concept, the Water and Terrestrial Elevation Recovery mission, will improve upon the SRTM design to permit multitemporal mappings of h across the world's wetlands, floodplains, lakes, reservoirs, and rivers. <s> BIB003 </s> Definitions and Mapping of East African Wetlands: A Review <s> characterized them as "…among (Kenya's) most important resources for social-cultural and economic development." <s> Over one hundred wetland specialists and Earth Observation experts from around the world gathered at the European Space Agency's 'GlobWetland Symposium: Looking at wetlands from space' in Frascati, Italy, from 19 to 20 October, 2006. The aim of the Symposium was to stimulate discussion between the two communities by reviewing the latest developments in Earth Observation (EO) for the inventory, assessment and monitoring of wetlands and identify key scientific, technical and policy-relevant challenges for the future. The results provide an overview of the key areas of current research in the use of EO for mapping and managing wetlands, while also pointing out gaps that could hinder global inventory, assessment and monitoring of wetlands. This paper provides a summary of the main outputs with a focus on the role of EO technologies in supporting the implementation of the Ramsar Convention on Wetlands. The summary contains a qualitative analysis of the state of the art and considers possible directions and priorities for future research, development and application of EO-based technologies in wetland management. In this context we: 1) highlight those applications where EO technologies are ready for wider uptake by wetland managers, and provide suggestions for supporting such uptake; 2) indicate where EO technologies and applications currently in the research and development stages could potentially be useful in wetland management; and 3) provide recommendations for new research and development of EO technologies, that can be utilized to address aspects of wetland management not covered by the range of current EO applications. <s> BIB004 </s> Definitions and Mapping of East African Wetlands: A Review <s> characterized them as "…among (Kenya's) most important resources for social-cultural and economic development." <s> BackgroundIn Uganda, nearly 1.4 million people are currently food insecure, with the prevalence of food energy deficiency at the country level standing at 37%. Local farmers are vulnerable to starvation in times of environmental stress, drought and floods because of dependence on rain-fed agriculture. Accordingly, the farmer’s means of increasing food production has always been an expansion of area under cultivation from virgin and fragile areas, especially wetlands. Consequently, Uganda has lost about 11,268 km2 of wetland, representing a loss of 30% of the country’s wetlands from 1994 to 2009. While the environmental importance of wetland ecosystems is widely recognized, their contribution to household food security is still hardly explored. In this paper an assessment of the contribution of wetland resources to household food security and factors influencing use of wetland resources in Uganda are reported.MethodsA number of livelihood tools in food security assessment including focus group discussions, key informant interviews, direct observations and a household questionnaire survey, were used to collect the data. A total of 247 respondents from areas adjacent to wetlands were involved in the household questionnaire survey conducted in three agro-ecological zones that are frequently characterized as food insecure.ResultsThe findings indicate that about 83% of the households experienced food insecurity. The main indicators of food insecurity were low harvest (30.9%) and when people buy locally grown food items (18%). Most households felt food secure when they had perennial crops (43.2%) in their gardens, or adequate money to buy food (23.9%). The prevalence of food insecurity was significantly lower among households with older and better educated household heads, but also among households located in Lake Victoria Crescent and South western farmlands agro-ecological zones, but significantly higher among households that were female headed, larger and participate in collection of wetland resources. Over 80% of the respondents reported that wetland resources provide products and services that contribute enormously to their household food security. Besides, they also indirectly contribute to food security by providing services that foster food production such as weather modifications and nutrient retention. Households with older heads and those that reside in the Lake Victoria Crescent agro-ecological zone when compared to counterparts in the Lake Kyoga agro-ecological zone are more likely to have a higher dependence on wetlands for food security.ConclusionsWith increasing population around the wetlands, coupled with land shortage and weather variations, households with limited options will continue to generally rely on wetlands for food security and income for sustaining their livelihoods unless alternative livelihood options are provided. There is thus a need to design appropriate food production technologies that ensure sustainable use of wetland resources for food security. <s> BIB005
An important dimension of food security is food production  , to which wetlands can and do contribute BIB005 . Inland wetlands in particular are vital for food supply; important to both agricultural production and fisheries BIB002 . This is especially relevant to East Africa, a region that has an extensive and acute history of food security crises. The situation in the region is considered to be serious and ongoing, with severe micronutrient deficiency present among children  , although the International Food Policy Research Institute's (IFPRI) Global Hunger Index currently shows slight improvements. At the end of 2014, food aid agencies were preparing for another drought in East Africa. Drought impacts regional food production negatively  and intensifies pressure for uncontrolled use of wetlands. The available water and associated fertile soils typically found in wetland environments provide excellent resources for local farmers. As a result, wetlands are endangered [9] , with land conversions, water withdrawals and overuse critical factors in wetlands conversion or destruction. It is estimated that globally, more than 50% of wetlands were lost during the twentieth century BIB002 . Climate change and the associated coping strategies of affected people are expected to exacerbate this trend in Africa  . The 1971 Ramsar Convention on the Wise Use of Wetlands (implemented by the Ramsar Convention Secretariat and commonly referred to as the Ramsar Convention), defines wise use of wetlands as "…the maintenance of their ecological character, achieved through the implementation of ecosystem approaches, within the context of sustainable development"  . If human claims to wetlands are to be effectively balanced against wetland ecosystem protection, spatially-explicit information is vital. Whereas local people might be well aware of the availability, extent and change in wetlands, institutional stakeholders need systematic and precise spatial information  . Reliable and comprehensive spatial data that are consistent across political boundaries can support agencies in wetland management and protection. The Ramsar Convention encourages research in the quantification of wetlands to obtain baseline information for future monitoring activities  . Wetland researchers having accurate information about wetland location and extent can enhance their focus on relevant study sites, extrapolate findings from case studies and "…undertake effective research"  . Our motivation for this review is the need for an up-to-date, regionally-consistent wetland map for East Africa and to provide basic information that can help with developing it through remote sensing technology. We have identified four fundamental requirements of such a map.  Cross-border alignment to avoid discontinuities within the East African region,  Comprehensiveness (within the constraints of the spatial resolution in reference to the pixel size of the sensor used),  A thoroughly documented methodology, and  Quality assessment based on ground truth or very high-resolution data. We argue that these map requirements can best be met by the application of remotely-sensed data and their analysis. A proposed data analysis scheme is provided in Section 4. The trans-boundary regional focus of a wetland map is important, because mechanisms to share information, including a common understanding of wetlands, support stakeholders in monitoring and protecting these endangered ecosystems BIB004 . Water moves across borders, and political decision processes on water-influenced ecosystems, like wetlands, can only be improved by regional cooperation BIB003 . The GlobE Wetlands project is a collaborative research effort between East African and German partners that was initiated in 2013  . As part of the GlobE-Securing the Global Food Supply initiative, this project is funded by the German Federal Ministry of Education and Research. Twenty partnering institutions from Kenya, Rwanda, Tanzania, Uganda and Germany work in an interdisciplinary partnership. The team aims to reconcile future food production with environmental protection by learning more about wetlands and promoting the wise use of these environments among decision makers and stakeholders in the East African region (Kenya, Rwanda, Tanzania and Uganda). The project aims to overcome the information gaps that exist between scientists and wetland managers BIB004 through the compilation of an international public wetland database and by fostering and sustaining close collaboration with decision makers in the institutional environmental sector on the ground. The nations of Kenya, Rwanda, Tanzania and Uganda are participants in the program and are therefore referred to in the material that follows as the East African region. Addressing this region for wetland research is of high interest due to the strong environmental gradient from sub-humid to semi-arid climatic regions that exists here. Within this transect, we find highly diverse geomorphological settings and seasonal patterns of vegetation growth. Therefore, wetlands develop in different formations, and reporting on different wetland types is essential to the research project. Two fundamental questions are addressed in this literature review:  "How are wetlands defined?" and  "Do wetland maps of the East African region exist and can they be improved by means of remote sensing?" This second question is addressed within the contexts of global, continental (African) and national maps. A comprehensive methodological review of wetland remote sensing is already provided by Ozesmi and Bauer BIB001 . Our study therefore does not emphasize analytic methods, but rather examines the availability of spatial data relevant to wetland environments and is focused on the East African region.