Pieter van der Zaag

• PhD
• Professor (Full) at IHE Delft Institute for Water Education

Problems manifested within social-ecological systems (SES) exhibit dynamic complexity and hold implications for current and future human well-being and environmental sustainability. The complexity of these issues, the ever-present uncertainty inherent to SES, and the multi-stakeholder settings in which they are discussed call for participatory mode...

Conventional water resources management models focus primarily on hydrological and economic efficiencies, often overlooking the socio-economic impacts of water distribution, potentially exacerbating inequalities. In this perspective, we propose an advancement in water resources allocation modelling frameworks to integrate distributive justice princ...

The construction of dams threatens the health of watershed ecosystems. The purpose of this study is to show how multiple dams in a basin can impact hydrological flow regimes and subsequently aquatic ecosystems that depend on river flows. The approach assesses the ecosystem services (ESs), including the tradeoffs between economic and ecological serv...

Conventional approaches to irrigation development involve large lumpsum investments in big infrastructure that cannot adapt to changing climate and socioeconomic conditions. There is an urgent need for alternative ways of investing in smallholder irrigation in Sub-Saharan Africa (SSA) that are adaptive and avoid capital lock-in. Adaptive Investment...

Water conflicts open windows of opportunity for grassroots movements to transform water systems. However, academic fields studying social movements in socio-environmental conflicts are not well equipped to deal with complexity, non-linear dynamics, and emergent properties. Therefore, these fields rarely engage with long-term complex social processe...

Water conflicts and negotiations between riparian states in the Nile Basin have mostly focused on legal, political, technical, and hydrological aspects of the river and dam construction. The contemporary cultural, emotional, and symbolic dimensions of the river and its dams have been largely overlooked. Therefore, this article explores how the Nile...

The social-ecological systems (SES) approach elicits a broad understanding of some of the most pressing socionatural challenges (e.g. resource scarcity, biodiversity loss, and climate change) and the responsibility that humans have in addressing them. System dynamics has proven a powerful paradigm for dealing with complex SES-related issues. Here w...

In Zimbabwe, farmer-led irrigation is far more widespread than planners and policy makers realise. Along the Shashani sand river, in the arid to semi-arid lands of south-western Zimbabwe, diverse farmer-initiated irrigation ventures exist. This qualitative case study focuses on bucket irrigation, in which very small vegetable fields of up to 450 m2...

Open-access remote sensing products provide data for transboundary water management. This study presents a comprehensive overview of the applications, uncertainties and implications of these remote sensing data products in the context of transboundary water management. Focusing on different stages within the transboundary cooperation continuum, we...

The construction of dams threatens the health of watershed ecosystems. The purpose of the study is to illustrate how multiple dams in a basin can impact hydrological flow regimes and subsequently aquatic ecosystems that depend on river flows. The approach assesses the ecosystem services, including the tradeoffs between economic and ecological servi...

The 2030 Agenda aims at ending extreme poverty, inequality, injustice and climate change. Progress is evaluated through a set of Sustainable Development Goals (SDGs), targets and indicators. However, there are various challenges affecting regular and timely reporting. Remote sensing (RS) derived data has been shown to provide a valuable complementa...

The construction of the Akosombo and Kpong dams in the Lower Volta River basin in Ghana changed the downstream riverine ecosystem and affected the lives of downstream communities, particularly those who lost their traditional livelihoods. In contrast to the costs borne by those in the vicinity of the river, Ghana has enjoyed vast economic benefits...

Este trabajo presenta un análisis y recuento de primera mano de los acontecimientos que llevaron a la histórica resolución del conflicto y la modificación del proyecto El Zapotillo después de dieciséis años de resistencia social. Las negociaciones entre el gobierno federal, la Conagua y las comunidades afectadas por este proyecto hidráulico tuviero...

Farmer-led irrigation is valued for its resilience and ability to cope with shocks and benefit from opportunities. Yet, typologies of farmer-led irrigation are mostly static categorisations without analysing farmers’ decision-making over time, and without studying ‘failed’ cases. We therefore analysed temporal changes in farmers’ irrigation strateg...

Water enables health, education, and economic well‐being opportunities for humanity. Access to basic water and sanitation services, freshwater variability, and water storage are some of the dimensions that may impact on human development worldwide. Yet few studies quantitatively explore the relationship between water and human development. This stu...

The construction of dams threats the health of watershed ecosystems. Addressing the health challenge 10 requires a clear understanding of the hydrologic effects of multiple dams with concurrent disturbances at the basin scale and their impact on watershed ecosystems. The purpose of the study is to examine the hydrologic, ecological, and economic im...

There is an urgent need in sub-Saharan Africa (SSA) to enhance irrigation access to meet the challenges of growing population and climate risk. To achieve this, big investments are currently planned in large irrigation infrastructure. We believe there is danger in following this conventional approach, which requires big lumpsum investments, locking...

Study region: Upper Cauvery river basin, India Study focus: Reservoir construction is one of the major contributors to changes in natural river flow regime characteristics. This study aims to understand the hydrological alterations resulting from the construction of reservoirs and water abstraction in the upper regions of the basin. The impacts o...

Access to accurate and trusted data for transboundary water management is important but not always sufficiently appreciated. Based on the Lake Victoria water levels decline, this technical note demonstrates that when a water crisis unfolds, tensions can arise because of absence of relevant data and uncertainty over data that are available. These ma...

The construction of the Akosombo and Kpong dams in the Lower Volta River Basin in Ghana changed the downstream riverine ecosystem and affected the lives of downstream communities, particularly those who lost their traditional livelihoods. In contrast to the costs borne by those in the vicinity of the river, Ghana as a whole, has enjoyed vast econom...

The growing competition for finite land and water resources and the need to feed an ever-growing population require new techniques to monitor the performance of irrigation schemes and improve land and water productivity. Datasets from FAO's portal to monitor Water Productivity through Open access Remotely sensed derived data (WaPOR) are increasingl...

Irrigation is commonly viewed as an activity fixed in time and place requiring permanent infrastructure. However, smallholder farmers in Sub-Saharan Africa engage in irrigation in diverse locations under different organizational modalities. This research analyses a flexible and dynamic form of irrigation driven by unique partnerships between migran...

In the semi-arid lands of southern Kenya, a dynamic process of farmer-led irrigation has developed over the past two decades. It is characterised by short-term agreements to access land and water. Resident and migrant farmers, capital providers and local landowners have engaged in diverse partnerships to benefit from water and land along the Olkeri...

Managers of urban water systems constantly make decisions to guarantee water services by overcoming problems related to supply–demand imbalances. A preferred strategy has been supply augmentation through hydraulic infrastructure development. However, despite considerable investments, many systems seem to be trapped in lacklustre development pathway...

The provision of flows for the environment, e-flows, is a means to restore the benefits of naturally flowing rivers. Despite the development of numerous methodologies to determine e-flows and optimize dam releases, actual implementation is relatively limited. Examples of successful e-flows implementation through dam reoperation exist in scientific...

This paper explores the concept of “institutional readiness” (IR) applied to the adoption and mainstreaming of Nature-based solutions (NBS) to deal with climate related risks. We argue that barriers towards up-scaling and mainstreaming of NBS are a manifestation of uncertainty, and are often associated with the ‘readiness’ of the institutional sett...

Water conflicts open windows of opportunity for grassroots movements to transform water systems. However, academic fields studying social movements in socio-environmental conflicts are not well equipped to deal with complexity, non-linear dynamics, and emergent properties. Therefore, these fields rarely engage with long-term complex social processe...

In this study the impact of sucrose accumulation in Sentinel-1 backscatter observations is presented and compared to Planet optical observations. Sugarcane yield data from a sugarcane plantation in Xinavane, Mozambique are used for this study. The database contains sugarcane yield of 387 fields over two seasons (2018-2019 and 2019-2020). The relati...

The Volta clam, Galatea paradoxa, is a freshwater macrobenthic bivalve which is endemic to the Lower Volta River in Ghana. The range of occurrence of the clam has been influenced by the flow regime in the Lower Volta which is in turn controlled by operation of two dams located upstream. Previous research has documented the changes to the Lower Volt...

The growing competition for the finite land and water resources and the need to feed an ever-growing population requires new techniques to monitor the performance of irrigation schemes and improve land and water productivity. Datasets from FAO’s portal to monitor Water Productivity through Open access Remotely sensed derived data (WaPOR) is increas...

Managers of urban water systems constantly make decisions to guarantee water services by overcoming problems related to supply-demand imbalances. A preferred strategy has been supply augmentation through hydraulic infrastructure development. However, despite considerable investments, many systems seem to be trapped in lackluster development pathway...

Integrating the planning of a multi-reservoir system in nexus with agricultural and electricity infrastructure could alleviate security concerns for these resources in regions where demand is growing while water and land scarcity are exacerbated by climate change and anthropogenic pressures. This study focuses on the benefits of resource integratio...

Waterlogging is an increasingly important issue in irrigated agriculture that has a detrimental impact on crop productivity. The above-ground effect of waterlogging on crops is hard to distinguish from water deficit stress with remote sensing, as responses such as stomatal closure and leaf wilting occur in both situations. Currently, waterlogging a...

The combined effects of socio-economic growth as well as climate change exert increasing pressure on international river basins and require dedicated cooperative efforts to jointly manage international rivers. Cooperative strategies drawn from scientific literature, empirical research and practitioner’s handbooks are explored and clustered into six...

Globally, freshwater resources are threatened, resulting in challenges for urban water supply and management. Climate change, population growth, and urbanization have only exacerbated this crisis. For the Caribbean, climate change through the impact of increasing temperatures and rainfall variability has resulted in more frequent and intense episod...

In recent years more recognition is given to the benefits and risks of private smallholder irrigation development across sub-Saharan Africa. It is acknowledged for its capacity to adapt to local circumstances and challenges. This study assesses the heterogeneous character of private smallholder irrigation in the challenging environment of southern...

The development of large infrastructure to address the water challenges of cities around the world can be a financial and social burden for many cities because of the hidden costs these works entail and social conflicts they often trigger. When conflicts erupt, science is often expected to play a key role in informing policymakers and social actors...

The process of development has led to the modification of river landscapes. This has created imbalances between ecological, economic, and socio-cultural uses of ecosystem services (ESs), threatening the biotic and social integrity of rivers. Anthropogenic modifications influence river landscapes on multiple scales, which impact river-flow regimes a...

Arjen Hoekstra postulated in 2001 that the value of water accumulates in an upstream direction: water value flows upstream. The ultimate source of this value is the rain. This original idea he used to develop the water value-flow concept. This article shows that the water value-flow concept has much to offer in terms of contemporary challenges. It...

Efficient irrigation water management for an 18,000 ha sugarcane plantation in Xinavane in southern Mozambique is a challenge. Sugarcane is an irrigation intensive crop and its productivity is sensitive to water stress. Options to adopt field water management best practices and proper irrigation scheduling are limited due to the lack of plot-level...

The endorheic basin of Zayandehrud in Iran suffers from environmental problems, social tensions, and economic instability. Lack of understanding how the water system and the socio-economic system interact may explain these challenges. A system dynamics model, being a holistic simulation tool, was developed for the Zayandehrud basin and used to eval...

Since there are various social factors and differences between different sectors of the system, ignoring water users’ attributes and their social behavior as well as considering only the homogeneous and up-down management scheme, would not be a successful approach in sustainable water management. Agent-Based Modeling is a relatively new approach th...

Dam construction and operation are known to alter the hydrology of rivers and degrade riverine ecosystems. In recent decades, the call to reverse these negative impacts by re‐operating dams has become stronger. Dams can support riverine ecosystems by releasing environmental flows (e‐flows). Unfortunately, despite the development of numerous methodo...

Abstract. Global trends suggest that cities around the world are increasingly depleting available water resources. A common strategy is to opt for supply augmentation infrastructure. However, this response can be a financial and social burden for many cities, because they entail developing expensive infrastructure and can trigger social conflicts....

Alluvial aquifers in seasonal rivers are a yet underutilised resource in many (semi-)arid regions of Africa. These so-called sand river aquifers provide nature-based water storage within easy reach because they are shallow. They form a significant potential renewable source of water for irrigation development. Innovative approaches and solutions ar...

Understanding the natural low flow of a catchment is critical for effective water management policy in semi‐arid and arid lands. The Geba catchment in Ethiopia, forming the headwaters of Tekeze‐Atbara basin was known for its severe land degradation before the recent large scale Soil and Water conservation (SWC) programs. Such interventions can modi...

A multi-country multi-sector computable general equilibrium (CGE) model is used to evaluate the economic and water resource scarcity effects of trade liberalization (removal of import barriers) and facilitation (removal of non-tariff barriers) among the Nile Basin countries. The analysis uses the new version of the GTAP-W model that distinguishes b...

Water scarcity exacerbated by growing demand in different sectors has created environmental, social, and economic challenges in the Urmia Lake Basin, Iran. Tackling this problem requires an integrated approach considering the basin as an interconnected system where a change in one sector affects others. Here, a System Dynamics Model is developed to...

Future climate projections for Southern Africa indicate an increase in the severity of droughts. Drought preparedness and management are important in such regions to minimise impacts on people and the environment. The aim of this study was to explore the responses of different institutions and actors to the 2015/2016 drought in the Komati catchment...

Much attention is being paid to the design and implementation of community-based monitoring initiatives of water and environment, and how to attract more citizens to participate in such initiatives. Although mass participation in collecting and sharing water-related or environmental data and good project design and implementation are key factors fo...

Community-based monitoring of water and environmental resources is believed to have the potential to help produce more or better water and environmental data, increase public participation in environmental monitoring, respond to issues of common community concern and enhance informed, democratic and transparent environmental decision making. Despit...

This is a chapter of a book entitled "The Grand Ethiopian Renaissance Dam and the Nile Basin: Implications for Transboundary Water Cooperation", which is edited by Zeray Yihdego, Alistair Rieu-Clarke, and Ana Elisa Cascão. It assess the transboundary economic impact t ofthe Grand Ethiopian Renaissance Dam under different climate and hydrological co...

This article provides an ethnographic example of a practice-based approach to water governance. It presents the situated case study of a canalero (canal operator) in the everyday water distribution of an irrigation system in Western Mexico. The canalero represents the low-ranked field operators at the frontline of many water provision organizations...

A novel integrated hydro-economic modeling framework that links a bottom-up partial equilibrium (en-gineering) model with a top-down (economic) general equilibrium model is developed for assessing the regional economic impacts of water resources management and infrastructure development decisions in a transboundary river basin. The engineering mode...

Understanding the relationship between hydrological processes and environmental changes is important for improved water management. The Geba catchment in Ethiopia, forming the headwaters of Tekeze-Atbara basin, was known for its severe land degradation before the recent success in integrated watershed management. This study analyses the hydrologica...

Integrated Water Resources Management (IWRM) is an approach that aims to change conventional water management. International agencies and organizations have promoted IWRM across the globe. The Lerma-Chapala Basin in Mexico is an archetypal case study on basin closure, where IWRM principles were said to have been applied in the early 2000s to help s...

Satellite rainfall products are an important source of rainfall data in un-gauged catchments. However, these products need to be validated as their accuracy can be affected by geographical position, topography, climate and embedded algorithms. Eight satellite rainfall products such as African Rainfall Climatology (ARC2), Climate Hazards Group Infra...

Land use and land cover (LULC) changes are continuous phenomena, often driven by natural and anthropogenic factors. In Ethiopia, a conversion of forest and grass lands into cultivated and urbanized lands has been reported. While such changes are known to have multidirectional impacts on river flows, erosion and sedimentation, and the socio-economic...

Scarcity of information on the water productivity of different water, land, and other ecosystems in Africa, hampers the optimal allocation of the limited water resources. This study presents an innovative method to quantify the spatial variability of biomass production, crop yield, and economic water productivity, in a data scarce landscape of the...

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...

This longitudinal study assesses the performance of the Dutch-German cross-border water regime using a combination of performance indicators. The regime has, despite many efforts over five decades, rarely progressed beyond policy making and hardly contributed to actual problem-solving for issues such as water pollution or river restoration. Stakeho...

A multidisciplinary examination of alternative framings of environmental problems, with using examples from forest, water, energy, and urban sectors. Does being an environmentalist mean caring about wild nature? Or is environmentalism synonymous with concern for future human well-being, or about a fair apportionment of access to the earth's resourc...

Ecosystems provide social, ecological and economic benefits and are linked through the landscape. Landscape degradation and loss of biodiversity undermine ecosystem functioning especially in vital ecosystems such as the Mara Basin in Africa. Holistically monitored and assessed landscape provide values to support conservation strategy which could en...

The concept of integrated water resource management (IWRM) attempts to integrate all elements of water resources. Different tools are developed to assist in developing sound IWRM plans. One such tool is multiobjective analysis using an integrated hydro-economic model (IHEM). However, IHEM mainly deals with the optimization of river flow (blue water...

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...

The limitation in quantity and quality of climate data, in particular rainfall measurements, directly affects the reliability of hydrological models, which negatively impacts on the quality of water resources planning and management. This is obviously true in poorly-gauged or in transboundary river catchments with limited practice of data sharing a...

The spatiotemporal variability of the Land Use/Cover (LULC) is a strong influence on the land management and hydrological processes of a river basin. In particular in semi-arid regions like the Tekeze-Atbara (T-A) basin, accurate information about LULC change is a prerequisite for improved land and water management. The human-induced landscape tran...

BACKGROUND • The impacts of drought has shown notable effects on the society, environment and economy of many countries (Van Loon, 2015) particularly in Africa where more than 60% of the population depends on rainfed agriculture. • Future climate projections for Southern Africa indicate more frequent and intense droughts with less rainfall and incr...

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...

Wastewater effluents from irrigation, and the domestic and industrial sectors have serious impacts in deteriorating water quality in many rivers, particularly in areas under tidal influence. There is a need to develop an approach that considers the impact of human and natural causes of salinization. This study uses a multi-objective optimization-si...

This chapter gives a brief description of coir& its properties, coir industry in general and the current scenario of coir in particular in the state of Kerala, South India. A detailed investigation is carried out through literature case studies in India and abroad regarding the application of coir geotextiles in soil and water conservation for crop...

A multi-country, multi-sector computable general equilibrium (CGE) model is used for the first time to evaluate the economic and water resource availability effects of trade liberalization (removal of import tariffs) and facilitation (reducing non-tariff barriers) under climate change in the Nile Basin. The analysis uses the GTAP 9 Database and the...

Mexico is considered a regional economic and political powerhouse because of the size of its economy, and a large population in constant growth. However, this same growth accompanied by management and governance failures are causing several water crises across the country. The paper aims at identifying and analyzing the drivers of water crises. Wat...