Stefan Uhlenbrook

• Prof. Dr.
• Strategic Program Director -- Water Food and Ecosystems at International Water Management Institute

Over the past 20 years, the Hydrological Ensemble Prediction Experiment (HEPEX) international community of practice has advanced the science and practice of hydrological ensemble prediction and its application in impact- and risk-based decision- making, fostering innovations through cutting-edge techniques and data that enhance water- related secto...

Access to sufficient and clean freshwater is essential for all life. Water is also essential for the functioning of food systems: as a key input into food production, but also in processing and preparation, and as a food itself. Water scarcity and pollution are growing, affecting poorer populations most, and particularly food producers. Malnutritio...

The Meki catchment in the Central Rift Valley basin of Ethiopia is currently experiencing irrigation expansion and water scarcity challenges. The objective of this study is to understand the basin’s current and future water availability for agricultural intensification. This was done by simulating scenarios through an integrated SWAT-MODFLOW model...

The sustainable agricultural intensification (SAI) debate, partly rooted in discussions over the Green Revolution, was developed in the 1990s in the context of smallholder agriculture in Africa. In many Sub-Saharan African (SSA) countries, production is still largely rainfed, with the prevalence of significant yield gaps and rapid environmental deg...

The United Nations Food Systems Summit aimed to chart a path toward transforming food systems toward achieving the Sustainable Development Goals. Despite the essentiality of water for food systems, however, the Summit has not sufficiently considered the role of water for food systems transformation. This focus is even more important due to rapidly...

Here, we aim to identify and validate core principles and outcome indicators for agro-ecological landscape resilience. We address four related questions: (1) which outcome indicators and process principles feature most prominently in the seminal literature on resilient agro-ecological landscapes? (2) to what extent are these principles represented...

Sustainable and resilient food systems depend on sustainable and resilient water management. Resilience is characterised by overlapping decision spaces and scales and interdependencies among water users and competing sectors. Increasing water scarcity, due to climate change and other environmental and societal changes, makes putting caps on the con...

This paper outlines a new and integrated water storage agenda for resilient development in a world increasingly characterised by water stress and climate uncertainty and variability. Storing water has long been a cornerstone of socio-economic development, particularly for societies exposed to large climatic variability. Nature has always supplied...

After more than three years of implementing the 2030 Agenda for Sustainable Development , the 2019 World Water Week in Stockholm chose to focus on inclusiveness with the theme "Water for society-Including all". This is also the theme of this Special Issue, which brings together the scientific highlights presented during the week. As connector acros...

The challenge of sustainable development is enshrined in the ambitious 2030 Agenda for Sustainable Development of the United Nations. The 17 goals and its various targets are unique with water being one of the cross cutting themes. Taking examples of past water dependent societies in a comparative setting, this paper challenges the new field of Arc...

Widely available digital technologies are empowering citizens who are increasingly well informed and involved in numerous water, climate, and environmental challenges. Citizen science can serve many different purposes, from the “pleasure of doing science” to complementing observations, increasing scientific literacy, and supporting collaborative be...

Ethiopia has decades of experience in implementing land and water management interventions. The overarching objectives of this review were to synthesize evidences on the impact of implementation of land and water management practices on agricultural landscapes in Ethiopia and to evaluate the use of adaptive management (AM) approaches as a tool to m...

Ethiopia has decades of experience in implementing land and water management interventions. Nonetheless, there remains persisting challenges to follow an adaptive management (AM) approach in efforts of restoring and transforming agricultural landscapes. This review was carried out to synthesize evidences on the impact on agricultural landscapes fol...

Understanding the spatiotemporal dynamics of surface water in varied, remote and inaccessible isolated floodplain lakes is difficult. Seasonal inundation patterns of these isolated lakes can be misestimated in a hydrodynamic model due to the short time of connectivity. The seasonal and annual variability of the Dinder River flow has great impact on...

The world is not on track to achieve Sustainable Development Goal 6 on clean water and sanitation by 2030. We urge a rapid change of the economics, engineering and management frameworks that guided water policy and investments in the past in order to address the water challenges of our time.

This introductory chapter describes the objectives and scope of the report, describing the main concepts related to water and climate, emphasizing the cross- sectoral nature of the challenges and potential responses, and highlighting those that are potentially the most vulnerable.

The Prologue provides an overview of the state of the world’s water resources and the potential impacts of climate change on the hydrological cycle, including water availability and quality, water demand, water-related disasters and extreme events, and ecosystems. Knowledge gaps, limitations and uncertainties are also addressed.

The implementation of afforestation programs in arid environments in northern China had modified the natural vegetation patterns. This increases the evaporation flux; however, the influence of these new covers on the soil water conditions is poorly understood. This work aims to describe the effect of Willow bushes (Salix psammophila C. Wang and Cha...

Stable isotope concentrations in the soil, rain and ground water have been used to trace the water extraction zones of plants in different environments. The need to identify the plant water use by plants in afforestation programs to control desertification increases the importance of sap water partitioning of plants in sand dune areas. However, the...

The Nile Delta Aquifer (NDA) is threatened by salt water intrusion (SWI). This article demonstrates an approach for identifying critical salinity concentration zones using a three-dimensional (3D) variable-density groundwater flow model in the NDA. An innovative procedure is presented for the delineation of salinity concentration in 2010 by testing...

Climate change, land use change, urbanisation, demographic development and migration, conflicts and peace, food demand and change of diets, globalisation 4.0 etc. are among the challenges with significant impacts on water that society faces. Water sustainability – in all its facets including water supply, sanitation, wastewater, water quality, floo...

The objective of this paper is to contribute to increasing the understanding of Arab policy-makers on the central role water plays in achieving the SDGs through facts and case studies of the Arab states and to serve as a call for action to Arab decision-makers on the importance of water for the achievement of the Sustainable Development Goals (SDGs...

Acknowledging and investing in stronger links between the SDG 6 on water and the various other water-related SDGs is an efficient and effective strategy for lifting millions of people from poverty and achieving the 2030 Agenda and the Arab Regional Strategies. Efforts to achieve SDG 6 will benefit socioeconomic development and the environment in th...

Building on the experience acquired by coordinating the production of the “UN-Water SDG 6 Synthesis Report 2018 on Water and Sanitation” and complemented with information coming from the latest editions of the United Nations World Water Development Report (WWDR; coordinated by WWAP on behalf of UN-Water), WWAP has presented the challenges related t...

As Egypt’s population increases, the demand for fresh groundwater extraction will intensify. Consequently, the groundwater quality will deteriorate, including an increase in salinization. On the other hand, salinization caused by saltwater intrusion in the coastal Nile Delta Aquifer (NDA) is also threatening the groundwater resources. The aim of th...

Phosphorus is a nutrient necessary for the development of crops and is thus commonly applied as fertilizer to sustain agricultural production. It occurs naturally, in indefinite quantities of uncertain quality in phosphate rock formations, but also accumulates in urban and livestock wastewater wherefrom it is often lost as a pollutant. Recovering p...

The variability of rainfall and climate, combined with land use and land cover changes, and variation in geology and soils makes it a difficult task to accurately describe the key hydrological processes in a catchment. With the aim to better understand the key hydrological processes and runoff generation mechanisms in the semi-arid meso-scale Kaap...

In 2015, UN Member States adopted the 2030 Agenda for Sustainable Development, including Sustainable Development Goal 6 (SDG 6): “Ensure availability and sustainable management of water and sanitation for all”. Commonly known as the ‘water goal’, SDG 6 went well beyond the limited focus on water supply and sanitation in the Millennium Development G...

The Eastern Nile Basin is facing a number of transboundary issues, including water resources development, and the associated impacts. The Nile Basin, particularly the Eastern Nile Sub-basin, is considered as one of a few international river systems of potential conflicts between riparian countries. The Eastern Nile is characterized by the high depe...

This study applies the soil and water assessment tool (SWAT), with climate (precipitation and temperature) outputs from four general circulation models (GCMs) and a regional circulation model (PRECIS), to evaluate (1) the impacts of climate change on reservoir sedimentation and (2) the impacts of climate change and reservoir development on sediment...

The economic development-environmental protection dichotomy is an out-dated construct. A 21st century approach to the world's water problems is progressively being developed by researchers and practitioners, who are combining traditional and ecosystem-based engineering systems to yield cost-effective solutions. Given the continuing and widespread l...

This paper investigates the effects of topographic heterogeneity on the runoff response simulated by a 0.05 degree (approximately 5.5 km) spatial resolution distributed hydrological model for the Pahang, Kelantan, and Muda river basins (25,600, 11,900, and 4010 km², respectively) in Peninsular Malaysia. Daily simulations were carried out and assess...

Phosphorus is is an element necessary for the development of crops and is thus commonly applied as fertilizer to sustain agricultural production. It occurs naturally at indefinite quantities, of uncertain quality, in phosphate rock formations, but also concentrates itself in urban and livestock wastewater wherefrom it is often lost as a pollutant....

Chemical hydrograph separation using electrical conductivity and digital filters are applied to quantify runoff components in the 1640 km² semi-arid Kaap River catchment and its sub-catchments in South Africa. A rich data set of weekly to monthly water quality data ranging from 1978 to 2012 (450 to 940 samples per site) was analysed at four samplin...

Despite Africa controlling the vast majority of the global phosphate it also faces the greatest food shortages – partially due to a lack of access to the fertilizer market. A more accessible source of phosphorus comes from wastewater flows, which is currently lost through the discharge to open surface waters. Analysing the potential phosphorus prod...

Mayas wetlands forms an important ecological zone in the arid and semiarid Sodano – Saharan region in Dinder and Rahad basins. They are the most unique feature of the Dinder National Park (DNP) and one of its three major ecosystems. “Mayas”, a local name for floodplain wetlands that are found on both sides along the Dinder and Rahad Rivers. Accordi...

Understanding the land use and land cover changes (LULCCs) and their implication on surface hydrology of the Dinder and Rahad basins (D&R, approximately 77 504 km2) is vital for the management and utilization of water resources in the basins. Although there are many studies on LULCC in the Blue Nile Basin, specific studies on LULCC in the D&R are s...

Understanding the land use and land cover changes (LULCC) and its implication on surface hydrology of the Dinder and Rahad basins (D&R) approximately 77,504 km² is vital for the management and utilization of water resources in the basins. Although there are many studies on LULCC in the Blue Nile basin, specific studies on LULCC in the D&R are still...

The demand for accurate satellite rainfall products is increasing mainly in areas where ground-measurement data are unavailable, inaccessible or unreliable. This paper aims to predict streamflow of the Dinder and Rahad rivers using satellite data and hydrological modelling. In this study, three widely used, satellite-based rainfall estimates (SBRE)...

The interactions between groundwater and surface water have been significantly affected by human activities in the semi-arid Hailiutu catchment, northwest China. Several methods were used to investigate the spatial and temporal interactions between groundwater and surface water. Isotopic and chemical analyses of water samples determined that ground...

The 2017 World Water Development Report shows that improved wastewater management is as much about reducing pollution at the source, as removing contaminants from wastewater flows, reusing reclaimed water and recovering useful by-products. Together, these four actions generate social, environmental and economic benefits for all society, contributin...

Daily gridded rainfall data over Peninsular Malaysia are delineated using an objective clustering algorithm, with the objective of classifying rainfall grids into groups of homogeneous regions based on the similarity of the rainfall annual cycles. It has been demonstrated that Peninsular Malaysia can be statistically delineated into eight distinct...

Hydro-climatic variability plays a pivotal role in structuring the biophysical environment of riverine and floodplain ecosystems. Variability is natural, but can also be enhanced by anthropogenic interventions. Alterations of hydro-climatic variables can have significant impacts on the ecohydrological functions of rivers and related ecosystems. Los...

Increasing water demand coupled with limited water resources has given rise to the need for sustainable water resources development in the Nile River Basin. Managing the basin’s water resources is complex because of its trans-boundary nature, exacerbated by environmental degradation and strong climate variability. The Nile basin water resources hav...

Mayas wetlands forms an important ecological zone in the arid and semiarid Sodano – Saharan region in Dinder and Rahad basins. They are the most unique feature of the Dinder National Park (DNP) and one of its three major ecosystems. “Mayas”, a local name for floodplain wetlands that are found on both sides along the Dinder and Rahad Rivers. Accordi...

The water balance dynamics and runoff components of a tropical forested catchment (46 km²) on the southwestern Pacific coast of Nicaragua were studied combining hydrometry, geological characterization and hydrochemical and isotopic tracers (three-component hydrograph separation). The climatic water balance was estimated for 2010/11, 2011/12 and 201...

This book provides experiences from studies on agricultural water management under climate change as references for agriculture and irrigation planners, decision makers, researchers and students. Chapters 2 and 3 provide an overview of global assessment of climate change impacts and water requirement for future agriculture. Chapters 4-7 provide ana...

Groundwater is the most important resource for local society and the ecosystem in the semi-arid Hailiutu River catchment. The catchment water balance was analyzed by considering vegetation types with the Normalized Difference Vegetation Index (NDVI), determining evapotranspiration rates by combining sap flow measurements and NDVI values, recorded p...

The understanding of runoff generation mechanisms is crucial for the sustainable management of river basins such as the allocation of water resources or the prediction of floods and droughts. However, identifying the mechanisms of runoff generation has been a challenging task, even more so in arid and semi-arid areas where high rainfall and streamf...

A long-term decline in ecosystem functioning and productivity, often called land degradation, is a serious environmental challenge to Ethiopia that needs to be understood so as to develop sustainable land use strategies. This study examines inter-annual and seasonal trends of vegetation cover in the Upper Blue Nile (UBN) or Abbay Basin. The Advance...

Ensemble hydrological predictions are normally obtained by forcing hydrological models with ensembles of atmospheric forecasts produced by numerical weather prediction models. To be of practical value to water users, such forecasts should not only be sufficiently skilful, they should also provide information that is relevant to the decisions end us...

The objective of this study is to understand the rainfall-runoff processes of the meso-scale Chemoga and Jedeb catchments in the Abay/Upper Blue Nile basin, Ethiopia. Distributed conceptual modelling and different field data were used in modelling process. Three different model representations with varying model complexity have been employed to tes...

Global climate change has received much attention worldwide in the scientific as well as in the political community, indicating that changes in precipitation, extreme droughts and floods may increasingly threaten many regions. Drought is a natural phenomenon that causes social, economical and environmental damage to society. In this study, we asses...

A long-term decline in ecosystem functioning and productivity, often called land degradation, is a serious environmental challenge to Ethiopia that needs to be understood so as to develop sustainable land use strategies. This study examines inter-annual and seasonal trends of vegetation cover in the Upper Blue Nile (UBN) or Abbay Basin. The Advance...

The Incomati is a semi-arid trans-boundary river basin in southern Africa, with a high variability of streamflow and competing water demands from irrigated agriculture, energy, forestry and industries. These sectors compete with environmental flows and basic human water needs, resulting in a "stressed" water resource system. The impacts of these de...

It is widely accepted that Integrated Water Resources Management (IWRM) is the way forward to respond to efficient, equitable and sustainable development and management of water resources. Additionally, IWRM has also strong linkages with variability in climate conditions which causes various challenges for IWRM approaches. Besides the annual climat...

The understanding of runoff generation mechanisms is crucial for the sustainable management of river basins such as the allocation of water resources or the prediction of floods and droughts. However, identifying the mechanisms of runoff generation has been a challenging task, even more so in arid and semi-arid areas where high rainfall and streamf...

In the present study, we developed a catchment hydrological model which can be used to inform water resources planning and decision making for better management of the Migina Catchment (257.4 km2). The semi-distributed hydrological model HEC-HMS (Hydrologic Engineering Center – the Hydrologic Modelling System) (version 3.5) was used with its soil m...

The water balance dynamics and runoff components of a tropical forested catchment (46 km²) on the southwestern Pacific coast of Nicaragua were studied combining hydrometry, geological characterization and hydrochemical and isotopic tracers (three-component hydrograph separation). The climatic water balance was estimated for 2010/11, 2011/12 and 201...

The synthesis of experimental understanding of catchment behaviour and its translation into qualitative perceptual models is an important objective of hydrological sciences. We explore this challenge by examining the cumulative understanding of the hydrology of three experimental catchments and how it evolves through the application of different in...

The study aimed at developing a tool to investigate the effect of prospective climate change (until 2100) on hydrology and productivity of rain-fed crops (wheat Triticum L., maize Zea Mais L., and rice Oryza L.) in the Indrawati river basin, Nepal, Himalaya. Climate scenarios from 3 climate models (GCMs), namely CCSM4, EC-Earth and ECHAM6, each one...

We applied graphical methods and multivariate statistics to understand impacts of an unsewered slum catchment on nutrients and hydrochemistry of groundwater in Kampala, Uganda. Data were collected from 56 springs (groundwater), 22 surface water sites and 13 rain samples. Groundwater was acidic and dominated by Na, Cl and NO3. These ions were strong...

The objective of this study was to quantify the impacts of land use/land cover (LULC) change on the hydrology of the Jedeb, an agricultural dominated mesoscale catchment, in the Abay/Upper Blue Nile basin, Ethiopia. Two methods have been used. First, the trends of certain daily flow variability parameters were evaluated to detect statistical signif...

Ensemble hydrological predictions are normally obtained by forcing hydrological models with ensembles of atmospheric forecasts produced by Numerical weather prediction models. To be of practical value to water users, such forecasts should not only be sufficiently skilful, they should also provide information that is relevant to the decisions end us...

Water exchanges between streams and aquifers influence the quantity and quality of water in both domains. Seasonal river–aquifer interactions were investigated in a tropical coastal area where tidal sand ridges control river discharge to the sea. The study site is located in southwestern Nicaragua, dominated by humid tropical hydro-climatic conditi...

Droughts are widespread natural hazards and in many regions their frequency seems to be increasing. A finer-resolution version (0.05° × 0.05°) of the continental-scale hydrological model PCRaster Global Water Balance (PCR-GLOBWB) was set up for the Limpopo River basin, one of the most water-stressed basins on the African continent. An irrigation mo...

Hydrological and geomorphological processes are key to mangrove forest growth and development. However, few mangrove hydrology studies exist in Central America. A 0.2 km2 mangrove forest on the Pacific coast of Nicaragua was investigated to determine the water balance dynamics during the dry season. The used multi-methods approach combined hydrolog...