Lisa-Maria Rebelo

Wetlands of sub-Saharan Africa: distribution and contribution of agriculture to livelihoods.

Wetlands contribute in diverse ways to the livelihoods of millions of people in Sub-Saharan Africa. In many places they are inextricably linked to cropping and livestock management systems. At the same time, increasing population in conjunction with efforts to increase food security is escalating pressure to expand agriculture within wetlands. The environmental impact of wetland agriculture can, however, have profound social and economic repercussions for people dependent on ecosystem services other than those provided directly by agriculture. Currently, the basis for making decisions about the extent to which wetlands can be sustainably used for agriculture is weak. This paper provides an overview of wetland distribution, type and condition across Sub-Saharan Africa. Findings from an investigation of wetland use conducted in Tanzania are presented. These highlight the reliance of communities on both wetland agriculture and natural resources, and show that the nature of household dependence varies significantly from place to place and as socio-economic status changes. Consequently, incentives to manage wetland resources will differ markedly, not only from one location to another, but also across socio-economic groups within the same community. This complexity highlights the need for critical analysis of the social and economic factors that underpin the dynamics of wetland resource use in the development of sustainable management plans.

Contribution of L-Band SAR to Systematic Global Mangrove Monitoring

Information on the status of and changes in mangroves is required for national and international policy development, implementation and evaluation. To support these requirements, a component of the Japan Aerospace Exploration Agencys (JAXA) Kyoto and Carbon (KC (2) to quantify changes in the structure and associated losses and gains of carbon on the basis of canopy height and above- ground biomass (AGB) estimated from the shuttle radar topographic mission (SRTM; acquired 2000), the ice, cloud and land-elevation satellite (ICESAT) geoscience laser altimeter system (GLAS; 2003-2010) and L-band backscatter data; (3) to determine likely losses and gains of tree species diversity through reference to International Union for the ConservationofNature(IUCN)globalthematiclayersonthedistributionofmangrovespecies;and(4)tovalidatemapsof changesintheextentofmangroves,primarilythroughcomparisonwithdensetime-seriesofLandsatsensordataandtouse these same data to describe the causes and consequences of change. The paper outlines and justifies the techniques being implementedandtherolethattheGMWmightplayinsupportingnationalandinternationalpoliciesthatrelatespecifically to the long-term conservation of mangrove ecosystems and the services they provide to society.

The Nile Basin: tapping the unmet agricultural potential of Nile waters

This paper provides an overview of poverty levels, hydrology, agricultural production systems and water productivity in the Nile Basin. There are opportunities to manage water better in the basin for use in agriculture to improve food security, livelihoods and economic growth by taking into account not only the water in the river, but also by improving management of the rain water. Crops, livestock, fisheries and aquaculture have long been important in the Nile but do not feature in the water discourse.

Earth Observation Based Assessment of the Water Production and Water Consumption of Nile Basin Agro-Ecosystems

The increasing competition for water resources requires a better understanding of flows, fluxes, stocks, and the services and benefits related to water consumption. This paper explains how public domain Earth Observation data based on Moderate Resolution Imaging Spectroradiometer (MODIS), Second Generation Meteosat (MSG), Tropical Rainfall Measurement Mission (TRMM) and various altimeter measurements can be used to estimate net water production (rainfall (P) > evapotranspiration (ET)) and net water consumption (ET > P) of Nile Basin agro-ecosystems. Rainfall data from TRMM and the Famine Early Warning System Network (FEWS-NET) RainFall Estimates (RFE) products were used in conjunction with actual evapotranspiration from the Operational Simplified Surface Energy Balance (SSEBop) and ETLook models. Water flows laterally between net water production and net water consumption areas as a result of runoff and withdrawals. This lateral flow between the 15 sub-basins of the Nile was estimated, and partitioned into

Smallholder groundwater irrigation in Sub-Saharan Africa: country-level estimates of development potential

The abundance of groundwater resources of Sub-Saharan Africa is generally well recognized, but quantitative estimates of their potential for irrigation development are lacking. This study derives estimates using a simple and generic water balance approach and data from secondary sources for 13 countries. Even with conservative assumptions and accounting for water demands from other sectors, including the environment, a 120-fold increase (by 13.5 million hectares) in the area under groundwater irrigation is possible for the countries considered. This expansion could improve the livelihoods of approximately 40% of the present-day rural population.

Shallow groundwater in the Atankwidi Catchment of the White Volta Basin: current status and future sustainability

The Atankwidi Catchment, which lies in the White Volta Basin in West Africa, is intensively cultivated by locals for economic gains. During dry seasons, farmers irrigate their crops, chiefly tomatoes, using shallow groundwater harvested from shallow ponds they dig using simple tools like an axe, hoe, bucket and bowls. Recent expansion in cultivated areas has brought to the fore the need to estimate the volume of shallow groundwater stored in the catchment’s underlying aquifer and to what extent it can sustain the incremental growth in irrigated areas.

Providing low-budget estimations of carbon sequestration and greenhouse gas emissions in agricultural wetlands

The conversion of wetlands to agriculture through drainage and flooding, and the burning of wetland areas for agriculture have important implications for greenhouse gas (GHG) production and changing carbon stocks. However, the estimation of net GHG changes from mitigation practices in agricultural wetlands is complex compared to dryland crops. Agricultural wetlands have more complicated carbon and nitrogen cycles with both above- and below-ground processes and export of carbon via vertical and horizontal movement of water through the wetland. This letter reviews current research methodologies in estimating greenhouse gas production and provides guidance on the provision of robust estimates of carbon sequestration and greenhouse gas emissions in agricultural wetlands through the use of low cost reliable and sustainable measurement, modelling and remote sensing applications. The guidance is highly applicable to, and aimed at, wetlands such as those in the tropics and sub-tropics, where complex research infrastructure may not exist, or agricultural wetlands located in remote regions, where frequent visits by monitoring scientists prove difficult. In conclusion, the proposed measurement-modelling approach provides guidance on an affordable solution for mitigation and for investigating the consequences of wetland agricultural practice on GHG production, ecological resilience and possible changes to agricultural yields, variety choice and farming practice.

The ALOS Kyoto & Carbon Initiative: enabling the mapping, monitoring and assessment of globally important wetlands

This Special Issue of Wetland Ecology and Management highlights activities undertaken under the framework of the ALOS Kyoto and Carbon (K&C) Initiative, which is an international collaborative project led by the Japan Aerospace Exploration Agency (JAXA). The K&C Initiative currently involves some 30 researchers from 20 countries, and aims to stimulate the development of regional-scale applications pertaining to forestry and wetlands using space-borne Synthetic Aperture Radar (SAR), with specific focus on the medium-long wavelength (Lband, 23.5 cm wavelength) SAR, which is particularly sensitive to vegetation structure and for detecting inundated environments. JAXA’s Advanced Land Observing Satellite (ALOS) Phased Array L-band SAR (PALSAR) was in operation between 2006 and 2011 and the unique global systematic acquisition strategy developed for the PALSAR instrument facilitated consistent, repetitive and cloud-free wall-to-wall observations of the earth’s surface at spatial resolutions as fine as 10–20 m. The ALOS PALSAR observations complemented those of its predecessor, the Japanese Earth Resources Satellite (JERS-1) SAR, which provided the first L-band SAR baseline for tropical and boreal forest monitoring in the 1990s. The rich archives of ALOS and JERS-1 data also provide key baselines against which to compare observations by the latest L-band sensor, ALOS-2 PALSAR-2, which was launched in May 2014. The papers featured in this K&C Special Issue focus on applications relating to wetlands characterisation, mapping and monitoring. They discuss the application of space-borne radar to various different wetland types, ranging from freshwater to coastal, and natural to manmade. The research collectively illustrates the fundamental importance of systematic observations to accommodate monitoring of the environment at local, regional and global scales. Guest Editors: Ake Rosenqvist, K&C Initiative Science Coordinator Lisa-Maria Rebelo, K&C Wetlands Theme Coordinator Maycira Costa.

Suitability and scenario modeling to support soil and water conservation interventions in the Blue Nile Basin, Ethiopia

BackgroundThe widespread land degradation in Ethiopia has necessitated extensive soil and water conservation interventions over the last four decades. Despite these the degradation of land continues. The conservation interventions in most cases were, and still are, predominantly top-down approaches following government directives. The success of these blanket approaches has been limited and an alternative approach needs to be devised. This paper attempts to identify alternative options for selecting appropriate soil and water conservation technologies based on the biophysical suitability of the landscape.ResultsThe results of this study suggest that with appropriate soil and water conservation measures, it is possible to reduce soil loss within the Blue Nile Basin by up to 600 million tons 46% within 5-10. The statistics on net soil loss reduction also indicate that successful implementation of conservation measures in only four administrative zones (out of 17) can potentially reduce up to 60% of the total soil loss in the Basin.ConclusionLandscape level modeling of soil and water conservation has enabled identification of appropriate conservation measures that can are suited to particular biophysical niches. A targeted approach to soil and water conservation is more efficient in terms of both financing and labour, in contrast to the traditional blanket approaches of the past.

A study of wetland hydrology and ecosystem service provision: GaMampa wetland, South Africa

Abstract The GaMampa wetland, a palustrine wetland, comprises less than 1% of the catchment but is widely believed to make a significant contribution to dry-season river flow in the Mohlapitsi River, a tributary of the Olifants River, in South Africa. The contribution of the GaMampa wetland to dry-season flow in the Mohlapitsi River and the impact of increasing agriculture on its hydrological functioning were investigated. Economic analyses showed that the net financial value of the wetland was US