Hydraulic Infrastructure Research Articles

Projecting dry-wet abrupt alternation across China from the perspective of soil moisture

Under a warmer climate, the enhancement of dry-wet abrupt alternation (DWAA) risk poses a great challenge for sustainable development. Here, we introduce a novel framework for DWAA detection based on our proposed soil moisture concentration index. By the end of this century, over humid southern China, the shift of soil moisture time series from anomalously wet to anomalously dry pattern, or the other way around, will be more abrupt. In addition, the proposed framework driven by Coupled Model Intercomparison Project Phase 6 simulations projects more widespread DWAA-affected areas over southwestern China, coastal regions of southeastern China, and the lower reaches of the Yangtze River, especially under a high emission scenario. The framework proposed in this study provides an efficient system for DWAA detection and prediction, and the findings of this study provide a reference for upgrading hydraulic infrastructure and mitigating future DWAA events.

The Effects of Scales on Modeling of Flow Patterns Over Spillway

Climate changes leading to extreme events when the occurrence and intensity of severe phenomena have impeded the development and rehabilitation of hydraulic infrastructure, such as weirs and spillways according to these new conditions. The scale physical model is one of the most important methods for designing these hydraulic structures. The selection of the model scale is necessary for model operation accuracy and design performance because of the effect of this process on design parameters resulting from the model. Scale effects can be seen through the large effect of some forces on the model that are not effective in reality, such as surface tension and viscosity forces, whose effect can be seen on the model with a relatively small scale, but are not effective on the structure at the actual size. The present study is trying to know how the physical model scales affect flow patterns over the spillway of small dam (less than 15m height) and the extent of this effect. Three physical model scales (1/30, 1/75, and 1/100) were used and compared with the actual size of the structure by numerical model (FLOW 3D). The physical and numerical models were tested with discharge values of (250, 350, 500, 750, and 1000) m3/s to evaluate the rating curve, discharge coefficients, pressure distributions, and energy dissipation. The results show the scale has significantly impacted the results, and it is preferable to avoid small scales. The 1/30 scale aligned more closely with the numerical model (the actual dimensions of the spillway) and strikes a compromise between measurement precision and expense. Therefore; the present study recommended using the scale 1/30 physical model or more for small dam spillway design.

Groundwater in the city of Pesaro (Marche, Italy): anthropic impact and interference with the urban environment

Groundwater in the urban area of Pesaro is a significant local resource, supplementing the main surfacewater supply from the external Metauro watershed. Nevertheless, since Pesaro’s groundwater is tapped from a coastal alluvial aquifer in a heavily anthropized environment, its use involves mutual impacts with the urban environment, which poses several constraints. Our work schematized the main interferences of groundwater with building works such as housing (i.e. foundations and underground works), hydraulic infrastructures, wells’ network development, and geoexchange projects. Moreover, the presence of a seawater wedge, historically intruding the aquifer, must be taken into account, alongside its potential evolution in changing climate scenarios. Contaminated sites were also analyzed, as they represent a critical issue when further groundwater withdrawals are planned. Due to these complex interactions, there is a need for renewed commitment to studying and monitoring the local water resource. This is also essential for promoting awareness among both citizens and the local government that its use will remain crucial for a long time.

Simulating cross-scale flow dynamics around offshore monopile foundations with a GFD-CFD coupled model

Flow dynamics are complex and undergo significant impact from offshore engineering infrastructures, such as wind turbines, involving interactions across different temporal and spatial scales. Individual numerical models of geophysical fluid dynamics (GFD) or computational fluid dynamics (CFD) face challenges in accurately representing these dynamics. To effectively capture the three-dimensional cross-scale flow around offshore infrastructures, we propose a generalized coupling framework that integrates the unstructured-grid Finite-Volume Community Ocean Model (FVCOM) for GFD and the Open Field Operation and Manipulation (OpenFOAM) for CFD. With the validation against the flume experiment, the common-boundary nesting method was developed to allow an accurate representation of flow dynamics around offshore hydraulic infrastructures. Idealized monopile foundation experiments demonstrate the model's capability to capture the formation of Karman vortex street, rotating horseshoe vortex under realistic astronomical tidal conditions. Application of this coupling framework to the offshore wind farm in Yangjiang, China, reveals flow direction lagging of 15° in the wake of a monopile under diurnal tide. This coupling approach, leveraging the strengths of both CFD and GFD models, provides a universal downscaling methodology in geophysical conditions, for a better understanding of the impact of offshore hydraulic infrastructures on the surrounding environment and further planning offshore engineering projects.

Investigating Flow around Submerged I, L and T Head Groynes in Gravel Bed

Riverbank erosion poses a significant threat to the stability and integrity of river training structures. River training structures such as groynes are important components of sustainable development as they play a crucial role in mitigating flood risks, controlling erosion, and supporting the habitat for aquatic organisms. The habitats vary largely according to the groyne type. A comprehensive comparative analysis of the flow field around the I, L, and T head groynes in the gravel bed is drawn. This study will be of immense use for riverbank protection in hilly terrain where streams are mostly dominated by the gravel bed. Laboratory experiments were conducted in a channel with a sediment bed as gravel of size 9.36 mm. Consistent flow conditions were maintained, with a flow depth (D) of 0.136 m and Froude no (Fr) of 0.61. The performance of these groynes, quantified using Lp (length of bank protection), was investigated. LHG and THG, notably, instigate more profound scour depths, recording values of 0.295 D and 0.29 D, respectively, while IHG trails with the value of 0.21 D. The complex flow field involving velocity peaks, decelerated, and negative flow is discussed and is attributed to flow separation at the groyne tip and the horseshoe vortex. The Lp for each groyne was estimated, with the IHG providing the maximum bank protection of 1.2 L1, L1 being the transverse length of the groyne. The cost–benefit analysis revealed IHG as the most cost-effective structure. These findings contribute to optimization of riverbank stabilization efforts, enhancing the resilience of hydraulic infrastructure and ensuring the safety and wellbeing of affected communities and ecosystems. The results also provide valuable insight into bank protection by various groynes and highlight their contribution to enhancing the resilience of river systems.

Immunity through technification? A critical review of water governance discourses in Tunisia

AbstractAfter Tunisia's independence from France in 1956, the country was engaged in what has been termed the “supply management policy”, that is, a maximum mobilization of water resources through large‐scale modern hydraulic infrastructure. Towards the beginning of the 1980s, the country entered a crisis and had to adopt in 1986, under pressure from the International Monetary Fund and the World Bank, a “Structural Adjustment Program” (SAP) that prioritized measures to improve economic efficiency and liberalize the economy. Since then, Tunisian water policy has progressively shifted towards “Integrated Water Resources Management” (IWRM). This review critically analyzes the water governance discourses that have framed these policy interventions. I will draw on academic research and official and civil society reports to suggest that these discourses have been “rendered technical”, stripping issues of any political (and therefore conflicting) character. When rendered technical discourses raise development projects and policies above the terrain of political contestation, the possibilities of action available to those opposed to them become limited. This depoliticization of development interventions through technical discourses narrows the public space of democratic debate. I will also argue that the “technification” (rendering technical) process is reversible. Opposition groups can challenge technical discourses with a critical approach that can reconfigure and alter the trajectory of governmental programs. However, critical discourses can, in turn, be rendered technical.This article is categorized under: Human Water > Water Governance Human Water > Rights to Water

Optimization of Irrigation Programming for Different Water Allocation Strategies at Network Level: Method and Application

Optimum irrigation programming at network level is important not only for maximum yield and benefit from the system but also for sustainable use of constrained resources. The subject of this investigation is to devise a method which enables optimum water allocation in irrigation networks, to apply it to a real system, and to analyze the results. In the first step, the irrigation district was divided into the most suitable water allocation zones considering the hydraulic properties of the canals. Next, alternative system rotation periods were defined in accordance with the properties of the research area, the hydraulic infrastructure of the irrigation network and the crop pattern. In this process, the model was run for five different water allocation strategies. The model was applied to the command area of Sarıkız Irrigation Association in the Ahmetli Regulator Right Bank Irrigation System in the Gediz Basin. Therefore, irrigation programs were prepared for the crop pattern, which receives water from 45 tertiary canals of the Y9 secondary. The irrigation time allocated to each tertiary canal and the amount of irrigation water were evaluated, together with the water shortage levels which occurred in these tertiary canals. The results indicated that the model defined the optimum system rotation period, the borders and the sizes of the most suitable water allocation zones, and the most suitable irrigation programs under the prevailing conditions. The proposed model can provide an insight for decision makers as a decision support tool.

Modelling of Granular Sediment Transport in Steady Flow over a Mobile Sloped Bed

This paper introduces a three-layer system, proposing a comprehensive model of granular mixture transport over a mobile sloped bed in a steady flow. This system, consisting of the bottom, contact, and upper zones, provides complete, continuous sediment velocity and concentration vertical profiles. The aim of this study is to develop and experimentally verify this model for sediment transport over a bottom locally sloping in line with or opposite the direction of sediment flow. The model considers gravity’s effect on sediment transport in the bottom (dense) layer when the component of gravity parallel to the bottom acts together with shear stresses associated with water flow. This is a crucial factor often overlooked in previous studies. This effect causes an increase in velocity in the mobile sublayer of the dense layer and significantly affects the vertical distributions of velocity and concentration above this layer. The proposed shear variation due to the interaction between fractions and an intensive sediment mixing and sorting process over a mobile sloped bed adds to the novelty of our approach. The data sets used for the model’s validation cover various conditions, including slopes, grain diameters, densities, and grain mobility conditions, from incipient motion to a fully mobilized bed. This extensive validation process instils confidence in the theoretical description and its applicability to real-world scenarios in the design of hydraulic infrastructure, such as dams, barrages, bridges, and irrigation, and flood control systems.

Tiny-Machine-Learning-Based Supply Canal Surface Condition Monitoring.

The South-to-North Water Diversion Project in China is an extensive inter-basin water transfer project, for which ensuring the safe operation and maintenance of infrastructure poses a fundamental challenge. In this context, structural health monitoring is crucial for the safe and efficient operation of hydraulic infrastructure. Currently, most health monitoring systems for hydraulic infrastructure rely on commercial software or algorithms that only run on desktop computers. This study developed for the first time a lightweight convolutional neural network (CNN) model specifically for early detection of structural damage in water supply canals and deployed it as a tiny machine learning (TinyML) application on a low-power microcontroller unit (MCU). The model uses damage images of the supply canals that we collected as input and the damage types as output. With data augmentation techniques to enhance the training dataset, the deployed model is only 7.57 KB in size and demonstrates an accuracy of 94.17 ± 1.67% and a precision of 94.47 ± 1.46%, outperforming other commonly used CNN models in terms of performance and energy efficiency. Moreover, each inference consumes only 5610.18 μJ of energy, allowing a standard 225 mAh button cell to run continuously for nearly 11 years and perform approximately 4,945,055 inferences. This research not only confirms the feasibility of deploying real-time supply canal surface condition monitoring on low-power, resource-constrained devices but also provides practical technical solutions for improving infrastructure security.

Prescriptive analytics for low and high water management in German waterways

Abstract The real-time management of multi-purpose storage reservoirs aims at an efficient operation of existing hydraulic infrastructure. This management process can be structured as a prescriptive analytics setup that considers both current and predicted system states to recommend actions and outline potential implications. In application to a reservoir and river system, it combines hydrological modelling components for the system schematization, observations and data assimilation for the identification of the current system state, meteorological and hydrological predictions as well as optimization-based techniques to support decision-making regarding reservoir operations. In this paper, we present the application of such a framework to the short-term management of the Eder and Diemel storage reservoirs. These reservoirs are operated by the German Federal Waterways and Shipping Administration (WSV) with the primary goal to support navigation in the River Weser during low flow periods. In addition, partially conflicting objectives such as flood protection, energy generation and recreation are considered. The implementation includes an explicit consideration of forecast uncertainty and its impact on the decision-making by using probabilistic forecasts in combination with a multi-stage stochastic optimization approach. We demonstrate the applicability of the approach based on low and high water use cases. Special attention is paid on the benefits of the probabilistic forecast in combination with the multi-stage stochastic optimization versus a deterministic setup. It provides an explicit translation of the forecast uncertainty in the decision variables, in this case the reservoir releases helping the operators to better anticipate the range of future release decisions. Furthermore, the stochastic approach is expected to provide more stable decisions in an operational setting, based on more stable forecasts by considering various possible realizations of the future instead of picking a single one, which gets random after 4–5 days.

Multivariate Hydrological Modeling Based on Long Short-Term Memory Networks for Water Level Forecasting

In the Department of Chocó, flooding poses a recurrent and significant challenge due to heavy rainfall and the dense network of rivers characterizing the region. However, the lack of adequate infrastructure to prevent and predict floods exacerbates this situation. The absence of early warning systems, the scarcity of meteorological and hydrological monitoring stations, and deficiencies in urban planning contribute to the vulnerability of communities to these phenomena. It is imperative to invest in flood prediction and prevention infrastructure, including advanced monitoring systems, the development of hydrological prediction models, and the construction of hydraulic infrastructure, to reduce risk and protect vulnerable communities in Chocó. Additionally, raising public awareness of the associated risks and encouraging the adoption of mitigation and preparedness measures throughout the population are essential. This study introduces a novel approach for the multivariate prediction of hydrological variables, specifically focusing on water level forecasts for two hydrological stations along the Atrato River in Colombia. The model, utilizing a specialized type of recurrent neural network (RNN) called the long short-term memory (LSTM) network, integrates data from hydrological variables, such as the flow, precipitation, and level. With a model architecture featuring four inputs and two outputs, where flow and precipitation serve as inputs and the level serves as the output for each station, the LSTM model is adept at capturing the complex dynamics and cross-correlations among these variables. Validation involves comparing the LSTM model’s performance with linear and nonlinear Autoregressive with Exogenous Input (NARX) models, considering factors such as the estimation error and computational time. Furthermore, this study explores different scenarios for water level prediction, aiming to utilize the proposed approach as an effective flood early warning system.

Analysis of canal discharge management through remodeled structure at Guddu Barrage

As vital hydraulic infrastructure, barrages and canals are crucial for agricultural irrigation in Sindh Province, Pakistan. Any deviation from the intended design discharge can significantly impact water resource management, leading to economic losses. The Ghotki Canal in Sindh faced challenges in receiving its allocated inflow, prompting an extension of the divide wall at Guddu Barrage to 589.59 ft. However, this extension inadvertently exacerbated the problem by reducing the Ghotki canal's inflow, resulting in a 166.7 ft gap between the original and extended divide wall segments. This study takes a unique approach, using a non-distorted physical model at a scale ratio of 1:85, to assess the influence of the divide wall gap across five scenarios, varying gap width and river flow rates from 100,000 to 500,000 cusecs. The findings highlighted the disruptive effects of the gap on flow regimes, notably affecting critical infrastructure such as the silt excluder and left pocket capacity. Alterations in the divide wall gap width predominantly impact the Ghotki Canal discharge while minimally affecting the Rainee Canal. Without a divide wall gap, the Ghotki Canal's head regulator draws 88% of the designated capacity, while the Rainee Canal consistently receives its total inflow share of 10,000 Cusecs. In conclusion, this study underscores the importance of structure remodeling in barrages for effective water resource management, emphasizing the need for nuanced approaches to optimize canal performance and sustain agricultural livelihoods and regional development.

Impacts of future climate and land use/land cover change on urban runoff using fine-scale hydrologic modeling

Future changes in land use/land cover (LULC) and climate (CC) affect watershed hydrology. Despite past research on estimating such changes, studies on the impacts of both these nonstationary stressors on urban watersheds have been limited. Urban watersheds have several important details such as hydraulic infrastructure that call for fine-scale models to predict the impacts of LULC and CC on watershed hydrology. In this paper, a fine-scale hydrologic model—Personal Computer Storm Water Management Model (PCSWMM)—was applied to predict the individual and joint impacts of LULC changes and CC on surface runoff attributes (peak and volume) in 3800 urban subwatersheds in Midwest Florida. The subwatersheds a range of characteristics in terms of drainage area, surface imperviousness, ground slope and LULC distribution. The PCSWMM also represented several hydraulic structures (e.g., ponds and pipes) across the subwatersheds. We analyzed changes in the runoff attributes to determine which stressor is most responsible for the changes and what subwatersheds are mostly sensitive to such changes. Six 24-h design rainfall events (5- to 200-year recurrence intervals) were studied under historical (2010) and future (year 2070) climate and LULC. We evaluated the response of the subwatersheds in terms of runoff peak and volume to the design rainfall events using the PCSWMM. The results indicated that, overall, CC has a greater impact on the runoff attributes than LULC change. We also found that LULC and climate induced changes in runoff are generally more pronounced in greater recurrence intervals and subwatersheds with smaller drainage areas and milder slopes. However, no relationship was found between the changes in runoff and original subwatershed imperviousness; this can be due to the small increase in urban land cover projected for the study area. This research helps urban planners and floodplain managers identify the required strategies to protect urban watersheds against future LULC change and CC.

'Who can tell me what potable water means?' The assessment of water quality in debates over hydraulic infrastructure in nineteenth-century Italy.

How water is perceived and represented has an impact on the relationships between a given society and its water infrastructure. Historians have identified a shift in the perception of water during the nineteenth century, which was connected to the development of chemistry. From an understanding based in Hippocratic medicine and natural history that treated it as an infinite variety of substances, water eventually became understood as a simple compound consisting of oxygen and hydrogen. This resulted in the abstraction of water from its social and environmental contexts, with consequences for the way water was managed. This article aims to demonstrate that such a view gives a mistaken intellectual coherence to a fragmented and conflicted process, which involved continuities, an adaptation of old frameworks to new social priorities, and fine changes in scientific thinking and practices. This paper examines the scientific and political debates concerning water infrastructure, surveys and analyses on water quality, medical reports and political measures in nineteenth-century Italy. Ultimately, the reduction of 'waters' to 'water' in Italy was more about determining who had the authority to assess water quality in the process of creating and stabilizing new power relations between the public and the private spheres than about the abstraction of water from its social and environmental contexts.

Enhancing GNSS Deformation Monitoring Forecasting with a Combined VMD-CNN-LSTM Deep Learning Model

Hydraulic infrastructures are susceptible to deformation over time, necessitating reliable monitoring and prediction methods. In this study, we address this challenge by proposing a novel approach based on the combination of Variational Mode Decomposition (VMD), Convolutional Neural Network (CNN), and Long Short-Term Memory (LSTM) methods for Global Navigation Satellite Systems (GNSS) deformation monitoring and prediction modeling. The VMD method is utilized to decompose the complex deformation signals into intrinsic mode functions, which are then fed into a CNN method for feature extraction. The extracted features are input into an LSTM method to capture temporal dependencies and make predictions. The experimental results demonstrate that the proposed VMD-CNN-LSTM method exhibits an improvement by about 75%. This research contributes to the advancement of deformation monitoring technologies in water conservancy engineering, offering a promising solution for proactive maintenance and risk mitigation strategies.

Dynamic Geomorphology of the Amu Darya Basin in Afghanistan: A Study of Physiography, Basin Erosion, and Channel Development

The morphological dynamics of rivers are motivated by way of a number of things, including floodplain sedimentation, channel migration, sediment transport, and hydrodynamics. A considerable information of the complicated dynamics of river structures is important to layout river initiatives which can be sustainable and environmentally conscious. Implementing thorough river control plans that include hydraulic infrastructure and ecological restoration projects is important to overcoming these boundaries. This solution will effectively manipulate competing needs for water resources whilst ensuring the preservation of the location's herbal heritage. In the cease, this study affords essential new understandings of the complex interactions between hydrological patterns, human hobby, and geological procedures within the Amu Darya Basin. The application of sustainable land control and water useful resource making plans in Afghanistan might be appreciably impacted with the aid of those findings. Afghanistan has a lot of freshwaters because the Hindu Kush Mountains receive a significant quantity of precipitation. An estimated 75 billion cubic meters of potential water resources, consisting of 57 billion cubic meters of surface water and 18 billion cubic meters of groundwater, are found in Afghanistan. The Amu Darya, Northern River Basin, Helmand River Basin, Harirud-Marghab River Basin, and Kabul River Basin make up the Indus River Basin, which provides around two-thirds of Afghanistan's freshwater resources. All of Afghanistan's rivers, with the exception of the Northern River, flow across international borders into neighboring countries. The distribution of water from the Amu Darya River was subject to limitations imposed by the USSR, which was previously known as the Union of Soviet Socialist Republics. The majority of the water is used mostly for farming. Protocol 566, formally ratified by the former USSR, allowed the transfer of water from the Amu Darya River to the four Central Asian Republics (CARs) of Tajikistan, Uzbekistan, Turkmenistan, and the Kyrgyz Republic. By investigating the bodily functions of the basin, which includes land erosion and channel development, this looks at seeks to enhance our understanding of the landscape evolution of the basin. Our intention is to improve our information of the landforms, tectonic activity history, and the consequences of climate change inside the region by utilizing geological studies and facts from faraway sensing.

Learning from medieval Italy: urban sustainability concepts from the heritage of hydraulic infrastructures. The cases of Venice, Siena and Bologna

PurposeFaced with the growing need to find new viable water supply models for urban areas, this article studies and maps the strategies and identifies the key criteria of sustainable development present in pioneering water supply systems in the medieval period. The main aim is to determine which of its innovative principles could be applied in present-day cities.Design/methodology/approachFrom a methodological perspective, two types of cases were established, such as water supply models for human consumption and pre-industrial hydraulic systems, all of which are located in Italy. For the first group, the cases of Venice and Siena were analysed, while for the second, in the context of the cities along the Aemilian Way, the case of Bologna was selected.FindingsFive key criteria resulted from the analysis of the cases: exploitation, self-sufficiency, maintenance, rationalisation and reuse. The said concepts were defined and contextualised within the framework of the Sustainable Development Goals.Originality/valueThe Middle Ages were a historic moment in technological reinvention, before the development of modern systems of sanitation. With very limited resources, these traditional systems focused on rational use and deep cultural and geographical knowledge. This is why its recognition is of great importance today, in a time full of instabilities, with a view to the work that needs to be done for the development of more sustainable communities.

Water, Wealth, and Engineering Wisdom: Shaping Tucumán's Agricultural Future, 1890-1910.

Focusing on Argentina's sugarcane province of Tucumán from 1870 to 1910, this article examines the processes of engineering professionalization in Argentina and its application to pressing environmental problems. Engineers were central to the processes through which elites in Latin America sought to attract foreign investment in agriculture, integrate their countries into the global economy, and provide expertise that enabled states to advance a techno-scientific imaginary based on liberal economic progress. Progressive bureaucrats and engineers, such as civil engineer Carlos Wauters, believed that they could use hydraulic infrastructure to transform Tucumán from an agricultural monoculture to a polyculture; others believed that infrastructure should be used to support a sugar monoculture. In exploring this issue, this article bridges the fields of engineering history, agricultural history, and environmental history. It also incorporates Latin America into global scholarship on the emergence and evolution of professional engineering.

Modelling the future climate impacts on hydraulic infrastructure development in tropical (peri-)urban region: Case of Kigali, Rwanda

The current global climate has shown a significant change, mostly resulting from human-induced activities. Frequent experiences of extreme rainstorms, deadly landslides, and floods followed by the destruction of roads, bridges, drainage, buildings, agriculture, and other infrastructures have been appearing across the globe along with extensive socio-economic effects including human lives losses whereby tropical Africa is among the greatly affected regions. Several studies in the region acclaim the increase of climate-related extremes due to a gradual climate variation. Hence, this study aimed to evaluate how existing water structures might respond to the future climate, which is getting more severe and frequent in the region. The study was conducted on the Nyabugogo River catchment (NRC), covering a huge part of the Kigali metropolitan area. It was carried out through a downscaled global climate model (CMIP6 GCM) projection coupled with a joint SWAT + hydrological model and HEC-RAS hydrodynamic simulation. The study showed that the annual precipitation in Kigali might keep increasing, resulting in increased risks of extreme weather events. The study identified up to 38% (+514.9 mm) annual precipitation increment, which resulted in more than a doubled flow rate (+28.0 m3/s) increment by the end of the century under a high greenhouse gas emission scenario (ssp585). As a result, hydrodynamic simulations revealed that the Bridge-1 in NRC might fail to accommodate the 50-year return peak storm under ssp585. Henceforth, there is a need to adopt high GHG emission scenarios in critical infrastructure development. Further, enforcing green-grey infrastructures in flood risk-low resilient areas is recommended to improve climate resilience. Thus, the results of this study might prove useful in climate-resilient infrastructure development and other pre-emptive adaptation practices, most importantly building anticipated resilience against climate-related hazards.

Irrigated urban agriculture: a mixture of farming scales, water flows and actors in Nairobi, Kenya

ABSTRACT Irrigated urban agriculture (IUA) is important for urban food systems and livelihoods but has many unknown socio-technical configurations. This article examines the dynamics of farm irrigation and associated sociotechnical arrangements in the Nairobi catchment. The research shows that there are five principal forms of IUA, differentiated according to land sizes, water sources and suitability, technicality, actors, and market orientation. The city service does not provide arrangements for hydraulic infrastructure or agricultural extension, and state agencies do not take IUA practices into account. The complexity of the socio-technical configurations calls for flexible governance arrangements that go beyond the established models.