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M.W. Ertsen

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Using technical models to enhance consultation in water management

Journal article (2025) - R. Schuyler Houser, Gerard Pijcke, Maurits Ertsen
Technical models are useful tool to address epistemic uncertainties but often fall short of attending to other types of uncertainty that characterize complex water challenges. It is unclear if and how they might be repositioned as a more deliberative tool to help deal with the many uncertainties related to problem framing, uncertain future conditions, and likely intervention effects at various scales. Through the case of a multi-stakeholder water quality project in East Java, Indonesia, this paper explores how technical systems modeling can be used to support consensus-building regarding the characterization of water pollution problems and adjacent policy goals, both in the use of outputs and in the process of model-making and attendant deliberation. The water quality model combines mapped terrestrial pollution source estimates with rainfall-runoff and pollution transport and fate process models to estimate localized, regional, and basin-wide impacts of various source-reduction scenarios on water quality. By visually identifying pollution source concentrations and illustrating estimated impacts of alternative strategies, the model offers a useful visual tool on which to anchor reframing discussions and scenario-building. In this way, the case demonstrates how modeling can be repositioned as an invitation for planners to simultaneously deliberate alternative problem structures alongside interventions to better deal with uncertainties inherent to water resources management. ...

Improving conservation modeling under global change

Journal article (2025) - Indushree Banerjee, Maurits W. Ertsen
Ecological models must mimic observed patterns to predict species responses to global environmental change. However, the observation of patterns is scale-dependent, which poses a fundamental challenge for conservation policy under increasing anthropogenic pressure. This paper examines how choices on temporal and spatial modeling scales affect our understanding of species adaptation to changing environments, using tiger conservation in Nepal's Bardia National Park as a case study. Case study analysis revealed how tigers adapt to climate-driven habitat modification through mechanisms invisible at coarse modeling scales. Different temporal scales uncovered distinct patterns of human-wildlife coexistence, while spatial scales shaped our understanding of how habitat connectivity affects adaptation. This scale dependency of observation determines which processes we can discover and predict. We provide four novel recommendations for scale-aware ecological modeling under global change: explicit documentation of scale contexts, probability models to compensate for abstraction, sensitivity analyses of scale choices, and connected models across scales. ...
The accomplishment of Sustainable Development Goals (SDGs) is intrinsically connected to improving livelihoods in the Rural Global South (RGS). RGS livelihoods are complex, showing multiple dimensions beyond mere economic considerations. However, many related development policies (over)simplify livelihoods to income thresholds, leading to flawed interventions. Adequate strategies to address RGS livelihoods require a much deeper understanding of their various dimensions and complexities. Q methodology (Q) is a powerful participatory research technique that enables the systematic study of different viewpoints on subjective topics. Moreover, it has the potential to identify and reveal previously unheard narratives, thus allowing us to question the traditional understandings of RGS livelihoods. Yet, as a time- and assistance-intensive technique, its implementation faces methodological challenges that are currently overlooked and ought to be considered. We selected and reviewed 50 Q studies applied to different forms of RGS livelihoods. First, we discuss several on-field Q limitations associated with the physical, logistical, social, and cultural constraints. Second, we draw on good practices and strategies to cope with these limitations. Notwithstanding the limitations and strategies, we advocate building Q capacities and the gender-balanced empowerment of local researchers. This may contribute to a better understanding of the nuances and challenges of RGS livelihoods. ...
Abstract (2024) - Schuyler Houser, Gertjan Geerling, Gerard Pijcke, Reza Pramana, Maurits Ertsen
Water managers and planners working within complex social-environmental systems are challenged with difficult choices when prioritizing interventions to manage water quality and reduce pollution from point and non-point sources. These choices are particularly important in low-resource environments where public funds must be carefully allocated. To support policy analysis for water quality management, a water quality modeling and policy consultation exercise was performed by Deltares, TU Delft, and government partners in the Brantas River basin, East Java, Indonesia. The modeling exercise combined mapped pollution source estimates for domestic wastewater and agricultural runoff with rainfall-runoff and pollution transport and fate models to demonstrate estimated impacts of various source-reduction scenarios on BOD loads along the main river. These outputs were used to inform deliberations regarding options to reduce water pollution and improve river health at a basin level. The model's ability to identify hotspots and assess the impact of targeted pollution reductions offers a powerful visual tool for policymakers to formulate geographically targeted interventions and identify the specific pollution source reductions that would yield the most substantial improvements. The case demonstrates the practical applications of scenario-building as an invitation for policy-makers to visually consider alternative interventions and focuses on lessons learned regarding capacities required to perform such activities, stakeholder engagement to build workable and meaningful model from an administrative perspective, and practical considerations for applying data-driven approaches to prioritization. ...
Next to the challenges of paramount importance represented by water scarcity, food security, energy transition, and environmental protection issues, the obstacles faced on the matter of water, sanitation, and hygiene (WASH) are immense. WASH interventions are essential to support human health, prosperity, and dignity, as they provide the base for an adequate standard of living. In many low- and middle- income countries, especially in rural and low-income areas, decentralized wastewater treatment systems (DEWATS) can offer a solution to convey, treat, and dispose of or reuse wastewater closer to the source and through smaller conveyance networks. In Indonesia, and as such in the Brantas basin on East Java, focus area of this study, the government has recognized DEWATS as their best available option for improving sanitation in dense low-income urban settings. Although the percentage of households with access to proper sanitation in the province of East Java has been increasing steadily, service coverage and the quality of sanitation systems still need to be increased to reach the desired coverage by 2024. Similar to other fields of application, within WASH and concerning DEWATS, stakeholders engagement, ethics and gender dimension are key topics to develop and strengthen integrated approaches. It is challenging to formulate targeted interventions in the watershed since they depend on the willing support of various stakeholders who may have different priorities (even within their own institutions), having diverse (and sometimes conflicting) viewpoints. This may result in stakeholders strongly contesting the appropriateness of various solutions. An exploration of stakeholder priorities is therefore needed to facilitate the application of wastewater treatment technologies. Due to its participatory approach and the type of interpretation that the method allows, Q-methodology was selected to explore this situation. Q-methodology is a set of techniques which allow for the study of ‘subjectivity’, combining statistics with the depth provided by qualitative data. It is composed of the data collection technique (called Q-sorting) and a data analysis step via correlation and factor analysis. In this contribution, we explore the perspectives and priorities of various stakeholders regarding decentralized wastewater treatment solutions to assess the applicability and acceptability of DEWATS in the Brantas river basin. This allows us to identify context-based criteria and challenges to the implementation of DEWATS in the Brantas watershed. As such, we propose the Q-methodology as a strong methodology to further develop the required transdisciplinary scientific efforts to promote relevant insights and solutions through meaningful, pertinent, and effective stakeholder engagement. ...
Journal article (2023) - R.S. Houser, K.E.R. Pramana, M.W. Ertsen
Recognizing the interrelatedness of water use and conceptual value of IWRM, progressive water resource management systems are moving beyond hierarchical arrangements toward more integrated networks. Increasing calls for participation recognize the value of broadened perspectives that provide both technical expertise as well as social, cultural, and administrative knowledge. Moreover, the call for evidence-based policy of '00s has been tempered by recognition of the political nature of data and science. As such, water decision-makers striving to coproduce and employ shared knowledge must grapple with integrating inputs from diverse participant groups to characterize policy problems and identify effective and feasible solutions. Participatory mandates, coordination bodies, and collaborative networks have emerged to facilitate such integration, and their effective cooperation and alignment relies upon some degree of shared purpose, rather than command and control. But guidance is limited with respect to how to accomplish such integrative aims, including how to support discussions across sectors and silos of practice in order to foster better understanding regarding the problems a policy network collectively aims to address. Motivated by observations within the discourse on water quality in the Brantas River basin in Indonesia, this research explores alternative concepts and problem structures regarding river health via Q methodology. Q methodology, an approach that uses factor analysis to explore human subjectivity, is applied to explore conceptualizations of water quality and the structures of the “water quality problem” in the Brantas. The results show that different groups of perspectives emerge regarding the concept itself, as well as characterization of the current condition of the Brantas. Surprisingly, these variant perspectives do not follow oft-cited government-business-civil society divisions. Moreover, the emergent perspectives demonstrate which aspects of the policy problem are consistent and which are contested, suggesting several starting points for early collaboration and several areas that require further research and facilitated deliberation. The results also offer participants in the collaborative network greater appreciation of the various perspectives and definitions in use, within and across organizations, when discussing water quality. ...
Journal article (2023) - Dengxiao Lang, Maurits W. Ertsen
Often, individual, communal, regional, or even national conflicts arise when water resources are shared and used. For equitable water-sharing strategies to be implemented, adequate collective action is required to allocate water – not limited to, but specifically in irrigation systems. In this research, we develop an Advanced Irrigation-Related Agent-Based Model (AIRABM) to explore issues of unequal access to water in relation to water use on farm and system levels. By simulating farmer activities and system management decisions within an irrigation system, our research aims to explore farmland dynamics in response to different levels of decision-making according to water availability. We incorporate both individual and collective decision-making processes to explore patterns in farmers’ yields and the dynamics of farmlands. Our results show that (1) within a prevailing trend of increasing yields for higher river discharge and gate capacity, (2) the influence of water availability is characterized by nonlinear changes in yields in response to variations in river discharge and gate capacity, revealing thresholds and tipping points, with (3) strategies for water redistribution partially alleviate inequitable water allocation between upstream and downstream farmers, although considerable variation persists in individual farmers’ and system-wide harvest outcomes. The AIRABM emphasizes individual and collective decision-making processes, encapsulating the uncertainty stemming from water availability and harvests of individual farmers. The modeling framework serves as a valuable tool to explore cooperative approaches in shared (water) resource management. Our findings provide meaningful suggestions to study and promote communication and (conditional) cooperation measures between farmers and management, thereby enhancing the effectiveness of irrigation water distribution. ...

How Small-scale Processes Could Contribute to Large-Scale Societal Development

Journal article (2023) - Dengxiao Lang, Maurits W. Ertsen
Early Southern Mesopotamia shows a complex history of expansion of (irrigated) farming in relation to urban developments and changing landscapes. As a first step to study expanding irrigated farming system, an irrigation-related agent-based model was developed to explore farm(land)s and irrigation systems in relation to decision-making processes, both of farms and their farmlands (an agriculture unit) and collective decision-making processes for irrigation system management—especially sharing water between farms. The decision-making processes include options to move farms, expand the system, or start a new system, as these would be options available for Mesopotamian farmers as well. In this text, we report how model parameters contribute to the generation of various patterns of yields and expansion of farms and system. Additionally, the Gini coefficient (based on yields) is applied to estimate levels of inequality among farmers. Our results show how (1) human decision-making determines the level of influence of and benefits for farms, as well as the overall irrigation system; (2) Gini values effectively capture the degree of inequality in yields among farms based on water availability; and (3) our model is a suitable base for further study, by incorporating additional agents into the irrigation system and expanding the spatial–temporal scales of the irrigated landscapes, to reach a more comprehensive understanding of the evolutionary dynamics of irrigation systems in Southern Mesopotamia. ...

Challenges for and lessons from the Barsha pump experience

Smallholder farmers (SFs) are cornerstone actors in eradicating poverty and hunger. Companies have recently focused on SFs as potential customers and suppliers. Several hindrances yet prevent SFs to be commercially viable actors. In this respect, sustainable business models (SBMs) bring opportunities for companies to increase profit, improve SFs' livelihoods, and promote environmental sustainability. Recognizing these opportunities, the Dutch company aQysta provides the Barsha pump (BP) as a sustainable irrigation solution for SFs. The challenges for BP adoption that remain for SFs illustrate that there is still limited understanding of how SBMs can support companies in engaging with SFs. To expand this understanding, we conducted a multiple-case analysis of 10 organizations providing SF-tailored products and/or services. Based on this analysis, we have drawn lessons for aQysta (and similar companies) to improve the BP's value proposition and we elaborate on the implications of this study for other organizations engaging commercially with SFs. ...
Journal article (2022) - Ileen N. Streefkerk, Marc J.C. van den Homberg, Stephen Whitfield, Neha Mittal, Edward Pope, Micha Werner, Hessel C. Winsemius, Tina Comes, Maurits W. Ertsen
Droughts and changing rainfall patterns due to natural climate variability and climate change, threaten the livelihoods of Malawi's smallholder farmers, who constitute 80% of the population. Provision of seasonal climate forecasts (SCFs) is one means to potentially increase the resilience of rainfed farming to drought by informing farmers in their agricultural decisions. Local knowledge can play an important role in improving the value of SCFs, by making the forecast better-suited to the local environment and decision-making. This study explores whether the contextual relevance of the information provided in SCFs can be improved through the integration of farmers’ local knowledge in three districts in central and southern Malawi. A forecast threshold model is established that uses meteorological indicators before the rainy season as predictors of dry conditions during that season. Local knowledge informs our selection of the meteorological indicators as potential predictors. Verification of forecasts made with this model shows that meteorological indicators based on local knowledge have a predictive value for forecasting dry conditions in the rainy season. The forecast skill differs per location, with increased skill in the Southern Highlands climate zone. In addition, the local knowledge indicators show increased predictive value in forecasting locally relevant dry conditions, in comparison to the currently-used El Niño-Southern Oscillation (ENSO) indicators. We argue that the inclusion of local knowledge in the current drought information system of Malawi may improve the SCFs for farmers. We show that it is possible to capture local knowledge using observed station and climate reanalysis data. Our approach could benefit National Meteorological and Hydrological Services in the development of relevant climate services and support drought-risk reduction by humanitarian actors. ...

Moral landscapes in Delfland, the Netherlands

Book chapter (2022) - M.W. Ertsen
Our built environment creates relations between ourselves and those who came before us: we are confronted with the morality of our ancestors. Two examples from the landscape around the Dutch city Delft suggest that material remains in that landscape—canals, sluices, embankments, and so on—represent historical ideas of right and wrong. The Orange Sluice stands symbolize how the practical need for managing water coincides with issues of power and control. Polder Berkel shows a changing local landscape, in which new goals created new connections between the local landscape and the larger area. These examples suggest that preserving historical elements is closely related to issues of power, identity, and access, just as the building of the original infrastructure was. ...
Journal article (2022) - Dengxiao Lang, Maurits Willem Ertsen
The literature on irrigated agriculture is primarily concerned with irrigation techniques, irrigation water-use efficiency, and crop yields. How human and non-human agents co-shape(d) irrigation landscapes through their activities and how these actions impact long-term developments are less well studied. In this study, we aim to (1) explore interactions between human and non-human agents in an irrigation system; (2) model the realistic operation of an irrigation system in an agent-based model environment, and; (3) study how short-term irrigation management actions create long-term irrigation system patterns. An agent-based model (ABM) was used to build our Irrigation-Related Agent-Based Model (IRABM). We implemented various scenarios, combining different irrigation control methods (time versus water demand), different river discharges, varied gate capacities, and several water allocation strategies. These scenarios result in different yields, which we analyse on the levels of individual farmer, canal, and system. Demand control gives better yields under conditions of sufficient water availability, whereas time control copes better with water deficiency. As expected, barley (Hordeum vulgare, Poaceae) yields generally increase when irrigation time and/or river discharge increase. The effect of gate capacity is visible with yields not changing linearly with changing gate capacities, but showing threshold behaviour. With the findings and analysis, we conclude that IRABM provides a new perspective on modelling the human-water system, as non-human model agents can create the dynamics that realistic irrigation systems show as well. Moreover, this type of modelling approach has a large potential to be theoretically and empirically used to explore the interactions between irrigation-related agents and understand how these interactions create water and yields patterns. Furthermore, the developed user-interface model allows non-technical stakeholders to participate and play a role in modelling work. ...
Despite extensive research on farmers’ constraints and decisions, technology developers, policymakers and development organizations still encounter difficulties in relating policies to farmers’ strategies. Often, the concept of ‘smallholders’ is applied as explaining and predicting farmers’ decisions – suggesting that specific strategies of farmers can be meaningfully related to their farm size. Our study into farmers’ decision-making concerning water transport technologies in Malawi suggests that this way of grouping farmers in policy and development programs does not match actual decision strategies. Using Q-methodology (Q) as a method allowed us to find decision-making patterns without predefining variables that would influence decision-making. We found that farmers within a predefined smallholder group did not decide in the same ways. Furthermore, our results show that decision-making has a clear gender dimension. We argue that Q is able to capture the nuances of farmers’ decision-making processes. As such, the methodology potentially provides a useful feed for policy and technology development. ...

Challenges and future opportunities

Journal article (2022) - Giulio Castelli, Luigi Piemontese, Ruth Quinn, Jeroen Aerts, Paul Elsner, Maurits Ertsen, Stephen Hussey, Walter Leal Filho, Natalia Limones, More authors...
Sand dams are impermeable water harvesting structures built to collect and store water within the volume of sediments transported by ephemeral rivers. The artificial sandy aquifer created by the sand dam reduces evaporation losses relative to surface water storage in traditional dams. Recent years have seen a renaissance of studies on sand dams as an effective water scarcity adaptation strategy for drylands. However, many aspects of their functioning and effectiveness are still unclear. Literature reviews have pointed to a range of research gaps that need further scientific attention, such as river corridors and network dynamics, watershed-scale impacts, and interaction with social dynamics. However, the scattered and partially incomplete information across the different reviews would benefit from an integrated framework for directing future research efforts. This paper is a collaborative effort of different research groups active on sand dams and stems from the need to channel future research efforts on this topic in a thorough and coherent way. We synthesize the pivotal research gaps of a) unclear definition of “functioning” sand dams, b) lack of methodologies for watershed-scale analysis, c) neglect of social aspects in sand dam research, and d) underreported impacts of sand dams. We then propose framing future research to better target the synthesized gaps, including using the social-ecological systems framework to better capture the interconnected social and biophysical research gaps on sand dams, fully utilizing the potential of remote sensing in large-scale studies and collecting sand dam cases across the world to create an extensive database to advance evidence-based research on sand dams. ...
Journal article (2022) - J.C. Intriago Zambrano, J.C. Diehl, M.W. Ertsen
Improved water management is an important strategy to support smallholder farming, and thus to foster food security and improved livelihoods. Within this strategy, technologies like water pumps, especially those operating on renewable energies, are key, as they are more environmentally sound and affordable alternatives. Their successful and sustained uptake is a complex process—largely dependent on the adopter and its surrounding context—usually overlooked by traditional linear technology-transfer approaches. By means of Q methodology, we explored cross-cultural discourses around the adoption of the Barsha pump (BP), a self-reliant hydro-mechanical device that does not require any external input than flowing water to operate. We administered the method to 43 (non-)farmer respondents linked to Nepali and Indonesian smallholder farming systems. We identified three relevant discourses, one of them bipolar in nature. These three groups accounted for 39, 36, and 28% of the total explained variance of our study. The first one identified BP's potential early adopters. The second discourse embodied the (stereotypical) highly dependent smallholder. The last one characterized (contrasting) views around the BP as an enabler of potential service-oriented business models to achieve wellbeing. These results reflect the need for a shift of mindset toward new ways of understanding technological change in smallholder settings. On the one side, simplistic one-size-fits-all models cannot connect to the diversity of issues and opinions as we found. On the other side, it is virtually impossible to produce tailored solutions to satisfy each of those individual realities. We propose possible adoption pathways that may lead to the exploration of innovative and adaptable business models that serve the diversity of smallholder farming needs more effectively. ...

How to connect agency and long-term effects in irrigation

Conference paper (2022) - Maurits Ertsen
On the basis of a data set from four research sites over the course of three agricultural years (2006/2007, 2012/2013, 2016/2017), this article empirically assesses the relations between land tenure security and smallholder farms’ crop production in Rwanda. We show that the general assumption that secure land tenure improves farm level harvests, is not found for smallholder farms in Rwanda. We defined a farmland tenure security index based on plausible threats as conveyed by smallholder farmers at each research site. Our findings indicate that the harvest of main crops did neither statistically correlate with this index, nor show differences from the mean at all research sites. Instead, factors mainly related to the ongoing crop intensification program, though threatening tenure security, contributed to the increase of small farm harvests. Lower land tenure security did not affect farmers satisfaction of the crop program, most of them claiming that in the end what matters most is that their harvests continue to increase. Therefore, in Rwanda, a new wave of agriculture strategizing contributes to increasing small farms’ harvest of prioritized crops and decreasing farm land tenure security simultaneously. ...
Journal article (2022) - Dengxiao Lang, Maurits W. Ertsen
An Advanced Irrigation-Related Agent-Based Model (AIRABM) of farmers' decision-making mechanism and feedback among farmers is developed. The model explores the interactions among human and non-human agents in the irrigation system. In this paper, we discuss harvest patterns as they result from more equal or unequal water distribution in the system. In a baseline model run, farmers are not restricted in their water use. For those situations that yields are low on the system or farmer level, we allow gate settings to be adjusted to improve poor harvest situations. Our model results show that 1) in the baseline scenario, upstream farmers generally receive more water and gain higher yields compared to downstream farmers; 2) gate capacity adjustments of upstream and middle stream farmers can push more water to downstream farmers, but those specific variations are considerable. We observe unexpected emerging system performance. The AIRABM model offers options for how combinations of individual farmers' decisions on water use and farming create (un)equal yield patterns in irrigation systems. ...
Journal article (2022) - K.E.R. Pramana, M.W. Ertsen
In the first decade of the 21st century, a water harvesting approach based on contour trenches—ditches to catch runoff—from Kenya was proposed as groundwater recharge technology in a semi-arid area in Ninh Phuoc district, Vietnam. In order to modify this solutions to tackle water scarcity, hydrological conditions at the site needed to be known. For such small-scale interventions, finding the most suitable set of (cheap and quick) efforts to study local hydrology is not easy. After our own study, we explored how different experts evaluated the chosen approach. The results from this evaluation suggest that different perspective for appropriate hydrological research can be found within a group of experts. This finding—in line with anthropologically inspired science studies—suggests that integrating different perspectives from stakeholders when working on suitable solutions in real-life water scarcity situations needs to be complemented with attention for different perspectives on the underlying hydrological processes and how they are to be studied. We discuss how this notion on the multiple perspectives intrinsic to hydrological research can be fruitfully included when developing water interventions. ...

Thought on Modelling Roman Responses to Climate (Changes)

Book chapter (2021) - Maurits Ertsen
Emerging societal complexity is closely linked to water systems within archaeology. When studying water-based societies, climate is usually conceptualized as an external force. Such an perspective risks missing how societal agents change both meaning and effects of climatic changes. This chapter proposes to develop an model-approach based on continuous interactions between humans and landscapes. The examples come from three case studies outside the Roman world: the Hohokam (500–1500 AD, current Arizona), the Zerqa Triangle, Jordan, during the Late Bronze Age (c. 1300–1100 BC), and the Maya city of Tikal (250 AD–900 AD, current Guatemala). The ideas that can be developed through these cases are compared to conceptualizations from recent publications discussing modelling of/in the Roman world. In general, this chapter argues that larger-scale and longer-term correlations have to be explained in terms of causalities between short-term agencies. ...