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Irrigation and fertilization are vital to increasing crop yield, but their application often exceeds crop requirements. Excessive fertilization under inefficient irrigation depletes the already scarce water resources while contributing to water pollution. To overcome these problems, the introduction of fertigation in combination with modern irrigation technologies has been promoted in the North China Plain (NCP), but farmers have been reluctant to adopt such technologies. To better understand the current situation and farmers' perceptions, we performed a case study in the People's Victory Canal Irrigation District (PVCID) of NCP. A field survey was carried out using a participatory approach, and field monitoring was conducted on a representative farm. We found that farmers are generally satisfied with their irrigation and fertilization practices, although they result in low application efficiency and distribution uniformity. In principle, the lack of knowledge about how to implement fertigation technology, the small-scale farming conditions, and the high cost of developing advanced fertigation systems are the main obstacles for fertigation adoption. We further conclude that (i) to improve the on-farm performance in terms of efficiency and uniformity of irrigation and fertilization, evidence-based guidelines are required to help farmers to implement; (ii) for effective adoption of new technologies, consideration of farmers' situation and perspectives is critical; and (iii) surface fertigation might be a good start for fertigation promotion.

Jordan’s water scarcity prompted a national plan whereby treated wastewater is utilized to amend agricultural irrigation water so as to reallocate freshwater to urban/domestic uses. The policy, however, has engendered farmers’ resistance in the Northern Jordan Valley (NJV), causing a stalemate in putting new infrastructure into operation. This research investigated the socio-economic causes of farmer resistance and contestation, and examined the government’s institutional approach to overcome the challenges. We found that the perceived risks of wastewater reuse such as salinization and restrictions from international markets figure prominently in the farmers resistance. As yet, farmers have managed to avoid the shift to treated wastewater use by using the political agency of elite farmers who control the Water Users Associations. These same farmers have adopted informal water access practices to overcome freshwater shortages. At the same time, small producers who don’t have possibilities to access extra water and with less political clout seem more willing to irrigate with treated wastewater. We conclude that understanding the heterogeneous context in which the envisioned wastewater users operate is key to predicting and solving conflicts that arise in treated wastewater reuse projects.

Although there seems enough water available for our global food needs, there are large areas with growing water scarcity. Food security in these water scarce areas cannot be met through self-sufficiency. The only option is to become more dependent on food imports which is increasingly risky due to volatility in production and food prices. Before 2008, declining food prices and increasing global cereal production favoured the food import strategy. The 2008 world food crisis represented a shock to this strategy and renewed attention was paid to the self-sufficiency strategy. The aim of this paper is to compare the food security strategies of Egypt and Jordan, two water-stressed, increasingly populated, oil-poor countries, pre and post 2008, by means of a food-water analytical framework using FAOSTAT data. Findings show that Egypt and Jordan have many similarities in their food security situation as both are highly dependent on food imports (Egypt 50%, Jordan 95%), and both have a reduced capacity to absorb future price increases. As food imports are inevitable under the water scarce context of Egypt and Jordan, it is important to focus on how to cope with volatilities. Our analysis shows that Jordan has better absorbed the costs of rising food imports than Egypt and that Egypt is trapped by its high domestic cereal production. Having revealed the limited options available to water-scarce countries for food security, we discuss the potential of grain reserves to cope with future price hikes and production shocks.The online version contains supplementary material available at 10.1007/s12571-022-01310-y.

Applying nitrogen fertilizer is commonly used to increase yields of surface-irrigated crops, despite often low application efficiency (AE) and distribution uniformity (DU). Surface fertigation, the application of fertiliser dissolved in irrigation water, is a promising technique for improved on-farm performance. This study evaluated surface fertigation strategies in a field experiment and by modelling with WinSRFR. The field experiment was conducted in the North China Plain in 2017–2019. The aim was to test different practices and for model validation, then to develop optimisation scenarios. The study found, first, that conventional practices resulted in low AE of irrigation, around 40 % in wheat season and 60 % in maize season. DU, however, was satisfactory in both wheat and maize seasons, averaging 80 %. Second, surge border irrigation showed no significant advantage in terms of performance compared to the conventional practice of continuous border irrigation. Third, the WinSRFR model offered satisfactory accuracy compared to field-measured data; and soil infiltration parameters, such as the Kostiakov K, showed temporal variation during the crop seasons. Fourth, improved fertigation scenarios were developed by optimising the cut-off ratio in tandem with changes in border length and fertigation timing. The optimised strategies resulted in AE and DU increasing to some 90 %.

In this paper a framework is presented for comparing the values derived from the different dimensions of water, without incurring the problems of commensurability. The framework is based on the concept of opportunity cost, which values any good by what one is willing to sacrifice to get it, which is a way of comparing seemingly different things. By simulating changes to a water resource and then measuring the economic, social and environmental impacts in metrics common and accepted by each dimension, a curve of the trade-offs between each metric can be derived. This makes trade-offs intrinsic to decision-making explicit.

Developments such as climate change and a growing demand for drinking water threaten the sustainability of drinking water supply worldwide. To deal with this threat, adaptation of drinking water supply systems is imperative, not only on a global and national scale but particularly on a local scale. This investigation sought to establish characteristics that describe the sustainability of local drinking water supply. The hypothesis of this research was that sustainability characteristics depend on the context that is analysed, and therefore, a variety of cases must be analysed to reach a better understanding of the sustainability of drinking water supply in the Netherlands. Therefore, three divergent cases on drinking water supply in the Netherlands were analysed. One case related to a short-term development (2018 summer drought), and two concerned long-term phenomena (changes in water quality and growth in drinking water demand). We used an integrated systems approach, describing the local drinking water supply system in terms of hydrological, technical, and socio-economic characteristics that determine the sustainability of a local drinking water supply system. To gain a perspective on the case study findings that are broader than the Dutch context, the sustainability aspects identified were paired with global aspects concerning sustainable drinking water supply. This resulted in the following set of hydrological, technical, and socio-economic sustainability characteristics: (1) water quality, water resource availability, and impact of drinking water abstraction; (2) reliability and resilience of the technical system and energy use and environmental impact; (3) drinking water availability, water governance, and land and water use. Elaboration of these sustainability characteristics and criteria into a sustainability assessment can provide information on the challenges and trade-offs inherent in the sustainable development and management of a local drinking water supply system.

The Russian invasion of Ukraine is disrupting global agricultural commodity markets, creating pressure on wheat supplies and stocks and consequently on food prices. The wider effects are felt around the world due to the dependencies inherent to global trade. But how to assess the vulnerability of countries food security and how to deal with it? To assess for which countries food security is at risk, dependencies along with a set of coping capacity indicators to absorb shocks need to be identified. Addressing vulnerabilities at this scale requires a global food security approach, because the food security of vulnerable countries depends on measure taken by other countries, together with a holistic approach to water, energy and food security. The Russian invasion brings to the fore the need to reassess the socio-economic value of agriculture and open trade, in terms of food security for stability in vulnerable regions.

Adaptation strategies are essential to manage water demand and ensure optimal use of available water resources under climate change. Identification and prioritization of adaptation options would greatly support decision-making in drought-prone Northwest Bangladesh. This study identified climate adaptation options by literature review and stakeholder consultation, then used multi-criteria analysis to evaluate and prioritize the options. The complexity of the options was also evaluated, specifically social, institutional, and technical obstacles to their local uptake. Seventy-two adaptation options were identified, spanning six sector categories. The options were further classified as in-system dependent, i.e., options that could be implemented by local actors, or as out-system dependent, i.e., options reliant on actions by external actors. Finally, they were defined as on-farm or off-farm strategies. Transboundary cooperation to increase surface water flows was ranked as the overall top-priority option, though this option is very complex and out-system dependent. Integrated water resources management and integrated crop management were the top-ranked options in the water management and crop production management sectors, respectively. Clustering scattered households and offering training programs in on-farm water management were the most and least complex measures, respectively. Stakeholders exhibited a clear preference for higher scale out-system dependent strategies, rather than in-system dependent options focused on changing the agricultural system itself to cope with climate change. Nonetheless, it is recommended that short-term and medium-term planning focus on opportunities to implement achievable adaptation measures within the local agricultural system. Investment in complex, externally dependent strategies is important for long-term planning.

Surface irrigation worldwide exhibits low efficiency due to excessively deep percolation and runoff. To optimize surface irrigation practice, two questions must be answered simultaneously: when to irrigate and how to irrigate (what stream size to use and for how long) to meet crop water requirements. Current surface irrigation optimization models are one-dimensional, meaning they can only simulate surface water flow, neglecting subsurface flow. They therefore indicate only how to irrigate, not when to irrigate. Furthermore, the required depth of irrigation is needed as input data for optimization, though this parameter is difficult to establish accurately. In addition, the effects of different irrigation practices on crop transpiration and yield, and variations in these across an irrigated field, are unknown. The present study adopts two one-dimensional simulation models – WinSRFR (for surface flow) and SWAP (for subsurface flow) – to determine when and how best to irrigate in a blocked-end furrow irrigation system for sugarcane cultivation in southwestern Iran. SWAP is used to determine irrigation schedule, required irrigation depth and crop transpiration along furrows, while WinSRFR is used to determine the soil infiltration function and evaluate and optimize irrigation practice. The results of the combined model approach indicate that some 2.7 times more water is applied than required in current practice, imposing high waterlogging stress on sugarcane crops. According to the SWAP simulations, the required irrigation depth is some 75 mm and the number of irrigation applications can be reduced from 26 to 19. The irrigation optimization in WinSRFR indicates that irrigation depth can be reduced from 162 mm to 81 mm, resulting in application efficiency increasing from 47% to 92%. Furthermore, as furrow slope increases from 0.02% to 0.12%, optimized stream size decreases from 3.0 to 1.6 l/s and optimized irrigation cutoff times increase from 3.2 to 6.5 hrs. Overall, optimization of irrigation practice using the combined model approach could result in 63% water conservation and 22% higher sugarcane yield.

Irrigation and fertilisation are often over-applied, which exceeds crop requirements. Surface fertigation, a technique of applying pre-dissolved fertilisers together with irrigation water, seems to be a viable way to improve the on-farm performance in the North China Plain (NCP). Thus, we conducted a field experiment based on farmers’ practices from 2017 to 2019. Moreover, we calibrated and validated SWAP-WOFOST-N, a seasonal integrated agro-hydrology and crop growth model, to assess the effects of different practices on yield, water and nitrogen use efficiency (WUE and NUE) and resource loss. Lastly, we developed various scenarios using the model to determine improved strategies. The results showed that the SWAP-WOFOST and extended Soil-N model offered satisfactory accuracy when compared with field measured data for the tested domain of the hydrological and nitrogen cycle; farmers’ current irrigation and fertilisation practices resulted in low WUE and NUE, but the practice of split top-dressing nitrogen did not show significant improvement in the surface irrigation system; WUE, NUE and nitrogen loss were closely related to irrigation practices. We further concluded that an optimised irrigation practice combined with an optimal fertigation scenario is the feasible strategy to achieve sustainable crop yield, high WUE and NUE and reduced nitrogen loss.

Subsidising irrigation is a legitimate approach that governments have used to achieve a set of social objectives. Yet it may simultaneously impose negative externalities, especially in the form of environment degradation. Could subsidies be reformed to be less harmful? To answer this question requires an insight into how various kinds of subsidies work, the interplay between subsidies and externalities, and the political complexity of subsidy reform. In this paper these insights are investigated using supply-demand graphs. It is argued in this paper that a broad definition of subsidies should be used, one that includes the implicit subsidies that result from partial cost recovery. It is also shown that even without subsidies, externalities due to irrigation would still exist and that any reform of existing subsidies will counter the positive impact irrigation may have, which may not be a desirable outcome.

In this study, the physical and economic impacts of four policy measures (crop diversification, improved watershed development, canal lining and reducing the level of reliability) all designed to improve bulk water supply, are assessed in a case study of the Musi catchment of India. The aim is to compare the impacts these policy measures have on the amount of bulk water supplied and the net economic returns across a complex multi-nodal catchment. It is argued that because it is policymakers who make decisions regarding these measures, an assessment of the private benefits to a subset of users would not be adequate. Rather, the society wide costs and benefits need to be considered. Using a hydroeconomic model of the catchment it was found that reducing the level of reliability was the most beneficial outcome from both a physical and economic perspective. The other three measures were found to have some adverse impacts on regions not directly affected by the measure.

Organic inputs as a substitution for, or addition to, chemical fertilizers can potentially mitigate N losses. However, it is not well known how their effects on N leaching and runoff depend on application approaches. We conducted a global meta-analysis of 129 studies to compare the effects of organic inputs on N export via leaching and runoff. We compared three application approaches: chemical fertilizer N substituted by organic fertilizer with: 1) equal amounts of total N or, 2) equal amounts of mineral N and 3) additional organic fertilizer N on top of chemical fertilizer. The meta-analysis showed that organic inputs reduced overall N leaching and runoff by 15% and 29%, respectively, without compromising crop yield, and that this effect was significantly influenced by the application approach taken. Organic substitution of chemical fertilizer N with equal amounts of total N decreased both leaching and runoff by more than 30% and hardly affected crop yield. Substitution with equal amounts of mineral N generally increased crop yield by 6% but also increased N leaching by 21%. Organic inputs in addition to chemical fertilizer N did not affect leaching and runoff. The differences between application approaches were reinforced with increased treatment duration. The loss ratios of leaching and runoff were 14% and 4.5%, respectively, from chemical fertilizer, and 9.2% and 2.6%, respectively, from organic fertilizer. The optimal substitution rates differed between leaching (40–60%) and runoff (60–100%) when substitution was based on equal amounts of total N. We conclude that substitution of chemical for organic fertilizer at equal amounts of total N is most effective in reducing N export via leaching and runoff without compromising crop production.

As global demand for food increases and impacts of climate-related extremes become more severe new governance mechanisms have become relevant. Individual and collective efforts by actors in water-for food governance could all contribute to sustainably managing the locally scarce water resources that are mobilized to meet the world's demand for food. This review synthesises insights from agricultural water management, water resources management and socio-hydrology to contribute to a knowledge base for informing joint efforts by networks of actors teaming up for sustainable water-for-food governance. The interpretation of water-for-food indicator values is complicated by spatiotemporal variations, different interests and perspectives. However, incorporating these complexities is crucial for governing a globalized food system that depends on water resources of which the availability varies in space and time.

Virtual water flows, incorporated in global food trade has increased the last decade. The drivers and consequences are complex. These complex relations between humans and water resources are studied from different perspectives. In this article, an overview of four such perspectives on water in global food production and trade is provided. These four perspectives are: (1) More crop per drop for increasing production, (2) Less drop per crop for reducing impacts, (3) National food security and import dependency; and (4) Local values and implications of water used in export food production. Each of the perspectives is valuable in the sense of representing different value frameworks, which represent contrasting norms and convictions, belief systems, and discourses; which are often incommensurable.

The regional effects of local water storage are largely unknown. This study identifies, categorizes and discusses the challenges in assessing the potential of local water storage. These are illustrated using a structured method applied to a Dutch case. We conclude that the focus must shift from storage ‘potential’ (the quantity of water that can be stored) to storage ‘feasibility’, which depends on exploitability, purpose and interactions between storage alternatives. Spatial and temporal scale also influence feasibility. Finally, farmers’ investment preferences are a factor, though these are shrouded in uncertainty. This overview is a first step towards improving storage assessment tools and processes.

Suitable adaptation strategies for dry season Boro rice cultivation under future climate change scenarios are important for future food security in Bangladesh. This study assessed the effect of shifting trans−/planting date of dry season Boro rice as an adaptation strategy, with focus on water requirements under future climate scenarios. Potential crop water requirement, effective rainfall and irrigation requirement to satisfy crop evapotranspiration of Boro rice were estimated using CropWat 8.0 for early, normal and late planting dates for 2050s and 2080s. Future climate scenarios were constructed using five global circulation model (GCM) outputs for RCP 4.5 and 8.5 by statistical downscaling and bias correction. Number of days exceeding the threshold temperatures (maximum of 35 °C and minimum of 25 °C) was counted for critical period of Boro rice to understand compatibility of the changed planting dates. Results indicate that late planting can substantially reduce irrigation demand by increasing rainfall availability during Boro growth duration, but the option is very limited due to both day- and night-time heat stress. An early planting, on the other hand, accounts for high water demand but ensures suitable temperature during the critical growth stages of the crop. The normal planting dates show the possibility of day-time heat stress. So, late planting of temperature-tolerant cultivars or early planting of high-yielding varieties would be recommended based on local water availability. However, adjustment of the planting date is currently limited because high temperature-tolerant cultivars are not available in the study region.

CONTEXT Climate change affects the timing and length of crop seasons. Adjusting sowing dates is a commonly recommended adaptation, but little is known about its efficacy in practice. OBJECTIVE This study investigated farm-level adjustments to sowing and harvesting dates (i.e., the growing period) in response to shifts in meteorological crop seasons during the last 30 years. Impacts on yields and farmers' complementary adaptation strategies were also examined. METHODS Using data from 287 farm households in four agroecological zones of the Indus Basin, Pakistan, we explored farmers' perceptions of shifts in seasons and adjustments in crop growing period. We verified these using meteorological station data on temperatures, precipitation and growing degree days. RESULTS AND CONCLUSIONS At lower altitudes (irrigated plains and mid-hills), the summer crop season had lengthened and the winter season shortened, but in both seasons the growing period was shorter, due to higher temperatures. The summer growing period was shorter by 5 (±11) days on the irrigated plains, while there was no significant change in length of the summer growing period in the mid-hills. The winter growing period was shorter by 15 (±6) days on both the plains and in the mid-hills, which negatively impacted yields. As an adaptation strategy, changing sowing dates was only somewhat effective in preventing yield losses. Farmers adopted complementary strategies, but these brought additional costs. At higher altitudes (valleys and mountains), the frost period had shortened, resulting in longer summer and winter crop seasons, and longer growing periods. The summer growing period was extended by 7 (±4) days in the valleys and 10 (±6) days in the mountains, while the winter growing period was extended by 3 (±3) days in the valleys and 13 (±5) days in the mountains, positively impacting yields. Farmers' adjustments in sowing dates did not necessarily parallel to seasonal shifts, as farm decision-making also had to consider risks linked to climate variability and management limitations. For the future, farmers at lower altitudes indicated limited further scope for adjusting sowing and harvesting dates. SIGNIFICANCE Our results contribute to a contextual understanding of farmers' responses to shifts in crop seasons. They indicate the need for adaptation planning to take advantage of extended growing periods in higher altitude zones, while supporting farmers in areas where seasonal shifts have negative impacts. Our findings furthermore indicate limits to adaptation in regions where agriculture is already challenged and provide suggestions for crop system-specific complementary measures.

Increasing climate variability will put crop production at risk, undermining the sustainability of agriculture-based livelihoods. Much effort has gone into assessing differential vulnerability – or who is at risk. However, the time dimension of increased risk – the when – is often only implicitly included in modelling, statistical and empirical studies. We define and explore the concept of “critical moments” (CMs); that is, periods of heightened risk during the year when farm households are vulnerable to specific climate hazards. The climate modelling, agronomy and socio-economics literature is reviewed to define different types of critical moments. Climate modelling emphasizes hazards but is less specific about the time window of risks in relation to crop cycles. Agronomy research develops cause-and-effect relationships between weather variables and yields by crop stage but generally does not consider hazard frequency and associated vulnerability. Socio-economic research analyses associations between hazards, yields and farm income, but often lacks full process knowledge, neglecting other pathways that contribute to vulnerability. Our synthesis aims to bridge disciplinary silos, and proposes an integrated concept towards risk. In this study, three types of CM are identified: CM’s with immediate, compound and shifted impact. The concept of critical moments is novel as it considers direct and indirect impacts as well coping strategies. Viewing climate risk to agriculture through a CM lens can support greater interdisciplinary engagement to identify vulnerabilities and develop and promote effective coping options and user-relevant support mechanisms to reduce vulnerabilities specific to particular places and moments.

Wastewater reuse is identified as strategic to help ameliorate scarcity in water-stressed regions around the world. However, to develop it, there is a need to better understand the social, institutional and technological contexts in which it takes place. This article develops a novel socio-technical framework to inform such an analysis and applies it to current wastewater reuse in Egypt. Our analysis highlights the different actors, management activities and practices that shape wastewater collection, transfer, treatment, discharge and/or reuse in different social, technological and environmental contexts in Egypt. It points out bottlenecks of current wastewater reuse policies and programmes.

Policies supporting rice production and investments in water infrastructure enabled intensification and diversification of farming systems in the Vietnamese Mekong Delta (VMD) over the past 20 years. Yet, demands of food security, economic development, and climate change continue to pose diverging and often conflicting challenges for water resources management in the upper, central, and coastal zones of the delta. The major changes effected in the VMD’s hydrological regime and land-use patterns are acknowledged in the literature, but few studies have examined the interplay between these dynamics at the delta scale. Based on time-series maps and statistical data on land-use, flooding, and salinity intrusion, we investigated the interrelations between land-use dynamics and changes in hydrological regime across the VMD in three representative periods. Land-use was found to be highly variable, changing by 14.94% annually between 2001 and 2012. Rice cropping underwent the greatest change, evolving from single cropping of traditional varieties towards double and triple cropping of high-yielding varieties. Aquaculture remained stable after rapid expansion in the 1990s and early 2000s. Meanwhile, flooding and salinity intrusion were increasingly controlled by hydrological infrastructure erected to supply freshwater for agriculture. Effects of this infrastructure became particularly evident from 2001 to 2012. During this period, spatial and temporal impacts on flooding and salinity intrusion were found, which extended beyond the rice fields to affect adjacent lands and livelihood activities. Unforeseen effects will likely be aggravated by climate change, suggesting a need to rethink the scale of planning towards a more integrated hydrologic approach.

Recent flood dynamics of the Mekong Delta have raised concerns about an increased flood risk downstream in the Vietnamese Mekong Delta. Accelerated high dike building on the floodplains of the upper delta to allow triple cropping of rice has been linked to higher river water levels in the downstream city of Can Tho. This paper assesses the hydraulic impacts of upstream dike construction on the flood hazard downstream in the Vietnamese Mekong Delta. We combined the existing one-dimensional (1-D) Mekong Delta hydrodynamic model with a quasi-two-dimensional (2-D) approach. First we calibrated and validated the model using flood data from 2011 and 2013. We then applied the model to explore the downstream water dynamics under various scenarios of high dike construction in An Giang Province and the Long Xuyen Quadrangle. Calculations of water balances allowed us to trace the propagation and distribution of flood volumes over the delta under the different scenarios. Model results indicate that extensive construction of high dikes on the upstream floodplains has had limited effect on peak river water levels downstream in Can Tho. Instead, the model shows that the impacts of dike construction, in terms of peak river water levels, are concentrated and amplified in the upstream reaches of the delta. According to our water balance analysis, river water levels in Can Tho have remained relatively stable, as greater volumes of floodwater have been diverted away from the Long Xuyen Quadrangle than the retention volume lost due to dike construction. Our findings expand on previous work on the impacts of water control infrastructure on flood risk and floodwater regimes across the delta.

Sustainable Development Goal indicator 6.4.1 is defined as the change in water use efficiency over time and measured as the change in the ratio of gross economic value added by irrigated agriculture, industry and the services sector to the volume of water withdrawn over time. The rationale behind this indicator is to decouple a country's economic growth from its water use. Yet, this unwittingly results in an economic distortion of the water balance, favouring increased water withdrawal in service of higher water-use efficiency, at the expense of environmental sustainability. This paper discusses three methodological flaws. First, aggregation of only economic values across all sectors ignores social and environmental values and is very sensitive to changes in the relative water use by agriculture versus industry and services. Second, the economic value derived from agriculture and from imports cannot in fact be decoupled from agricultural water use. Third, the indicator completely ignores the effects of diminished return flows to the environment due to increased re-use of water. A novel alternative, disaggregated WUE approach is therefore proposed, which links water consumption to the water balance. It is defined as the economic value of irrigated and rainfed agriculture combined with water consumption (ETa) by rainfed and irrigated agriculture per area based on earth observation data. It is measured as the change in the ratio of gross economic value added by irrigated and rainfed agriculture to the volume of water consumed by rainfed and irrigated agriculture over time. This approach is more consistent and objective, while being methodologically, hydrologically and environmentally sound. It acknowledges the coupling of economic growth and water depletion, and the need to strike a balance between opportunities for economic growth and environmental sustainability. This better serves the full breadth of the water and sanitation goal as defined in SDG 6.

A dense dike system has been built in the upstream floodplains of the Vietnamese Mekong Delta, allowing large scale rice production based on compartmentalized fields and optimized water management. Intensive cultivation has enabled farmers to greatly increase their rice productivity and augment the national food bowl. However, flood-control structures have undermined the water retention capacity, compromising various benefits of floodwaters for delta ecosystems. Effects are both internal and external to farming. Negative internal effects are the large investment requirements and higher farming costs. Negative externalities include increased flood damage, reduced sediment flows, saltwater intrusion and riverbank erosion. In this study, we assessed the effects of three dike–agricultural system scenarios on delta-level sustainability, considering both internal and external effects. Direct and indirect costs were estimated using various methodologies and the literature. Our findings show that extensive development of high dikes on the floodplains is the least economical and most ecologically risky alternative. In this scenario, accelerated high-dike construction exacted a cost 136% greater than the situation represented by the baseline year of 2011. Externalities in this scenario contributed to rising economic losses in both aquaculture and agriculture. The scenario of transforming high-dike into low-dike systems revealed lower water management costs combined with lesser environmental impacts and greater capacity to exploit floodwater benefits. Our findings provide a useful input for decision-makers considering the unintended economic consequences of existing water management strategies. They support a transition to low-dike farming systems for a more sustainable delta.

Regional long-term water management plans depend increasingly on investments by local water users such as farmers. However, local circumstances and individual situations vary and investment decisions are made under uncertainty. Water users may therefore perceive the costs and benefits very differently, leading to non-uniform investment decisions. This variation can be explored using crossover points. A crossover point represents conditions in which a decision maker assigns equal preference to competing alternatives. This paper presents, applies, and evaluates a framework extending the use of the concept of crossover points to a participatory process in a group setting. We applied the framework in a case study in the Coal River Valley of Tasmania, Australia. Here, farmers can choose from multiple water sources. In this case, the focus on crossover points encouraged participants to engage in candid discussions exploring the personal lines of reasoning underlying their preferences. Participants learned from others&rsquo, inputs, and group discussions elicited information and insights considered valuable for both the participants and for outsiders on the factors that influence preferences. We conclude that the approach has a high potential to facilitate learning in groups and to support planning.

This article uses the lens of the Multiple Streams Approach to explore whether the agendas set by political actors in Vietnam converged with the agenda set in the Mekong Delta Plan (MDP). The MDP presents policy choices for the development of the Vietnamese Mekong Delta. The plan offers economically attractive, climate adaptive and environmentally sustainable paths forward in the face of climate change and economic uncertainties. We collected our data using qualitative techniques, including a literature review and interviews. We found convergence between the MDP’s agenda and political actors’ agendas, though divergences were also detected. Between the delivery of the MDP in 2013 and formal endorsement of its ideas in 2017, the problem stream, policy stream and politics stream were brought together by the actions of “policy entrepreneurs” (scientists and experts). Our findings suggest that agenda-setting and convergence were a crucial step towards endorsement of the strategic delta planning process for the Mekong Delta. Further research could explore issues of power mobilization in enabling or constraining decision-making. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

The increasing policy interest in valuing water raises questions about practical roles or applications. Is valuing water intended, for example, to inform public policy and businesses, guide resource allocation, support a multi-stakeholder process, manage conflicts of interest, or to inform realistic pricing systems and support investment decisions? Decisions affecting water often fail, however, to consider ecosystem needs and social objectives and impacts in other geographical areas. This paper reflects on the essence of valuing water in practice. The paper concludes that in practice, valuing water is indeed useful in decision-making, not solely in the sense of it contributing to the value determination (as values are typically disputed, partial, incommensurable and imperfect), but more in offering a structured and transparent mechanism that supports an inclusive stakeholder water resources management process. Water valuation can play a key role in making explicit the trade-offs intrinsic to decision-making and priority setting, especially when it concerns societal needs such as food security and stability, which are not revealed in the marketplace. As such, valuing water may be a key tool in water diplomacy, whereby its value lies not so much in its numerical assessment as in the process it offers to engage stakeholders across different perspectives and interests in water use.

Climate change poses an acute threat to the Vietnamese Mekong Delta (VMD). To respond to this threat, the structure of the delta’s agriculture-based economy must transform, becoming more adaptive to changing conditions. One adaptive livelihood option is the use of flood-based farming systems in the upper VMD. The present study examines local perceptions of such a system in Dong Thap Province, a lowland, flood-affected area of the upper VMD. Specifically, we explored lotus farming as a potential flood-based adaptive livelihood model for the region. The study advances the current literature by using historical research, embedded in narrative analysis applying the social construction of technology (SCOT) lens. We collected data through in-depth interviews and field surveys to qualitatively analyze the emergence and status of lotus cultivation in the study area, zooming in on how local society evolved with expansion of this farming model. The findings suggest that as an innovative idea, lotus farming initially emerged due to unfavorable natural conditions, and then was developed as an attractive nature-based livelihood, and thus received increased attention. It has been accepted and modified over time according to the new interests of further stepped-in stakeholders. Our findings echo the social construction of technology perspective as we found lotus farming to be a technological artifact that did not develop on its own, by was driven by different interpretations and re-negotiation process. This made more room for stakeholders to shape and reshape it in a way that fits their interests.

Although water harvesting is receiving renewed attention as a strategy to cope with increasing seasonal and inter-annual rainfall variability, many centuries-old local water-harvesting reservoirs (tanks) in India are rapidly deteriorating. Easy access to groundwater is seen as one of the major threats to their maintenance and functioning. Potentially, however, conjunctive use of water from rain, tanks and groundwater reserves, supported by proper monitoring, could improve the resilience and productivity of traditional tank irrigation systems. To date, few quantitative multi-annual analyses of such climate-smart systems have been published. To redress this, we assess the sustainability of a rehabilitated tank irrigation system, by monitoring all inputs and outputs over a period of six years (12 cropping seasons). Our results show that during the period considered, improved conjunctive use resulted in a more stable cropping intensity, increased economic water productivity and higher net agricultural income. Groundwater tables were not negatively affected. We argue that improved conjunctive use can considerably reduce the vulnerability of tank irrigation to rainfall variability and thus is a valuable strategy in light of future climate change.

Flooding is a serious problem in Jakarta, and detailed estimation of flood damage is necessary to design optimal flood management strategies. This study aims to estimate flood damage in a densely populated area in Jakarta by means of a survey, to develop the relationship between flood characteristics and flood damage, and to compare the damage estimates from the survey with the damage estimates obtained by a flood damage model for Jakarta, i.e. the damage scanner model. We collected data on economic losses of the January 2013 flood in a survey of flood-affected households and business units in Pesanggrahan River. The actual flood damage in the survey area is US$ 0.5 million for the residential sector and US$ 0.7 million for the business sector. The flood damage for a similar event in the same area based on the damage scanner model is estimated to be US$ 1.3 million for the residential sector and US$ 9.2 million for the business sector. The flood damage estimates obtained by the survey approach are lower compared to the damage scanner approach due to different ways in obtaining flood damage data and in defining the maximum flood damage per object, the different spatial levels of analysis, and uncertainties in constructing the flood damage curves that were applied in the damage scanner model.

In India the stresses on water resource systems have increased, due in part to increased demand for scarce water supplies. Yet, what could be of greater concern is the potential long-run threats of climate change affecting supplies. Before thinking of a policy response to these long-run concerns, the impact of climate change on the reliability of water supply across a catchment needs to be gauged from both a physical and an economic perspective. Once these impacts are known, a more target approach to policy can be formulated. The aim in this research is to briefly present and comment on the results of an assessment of some these dynamic interacting forces across the Musi catchment in India. Of primary interest are the impacts of three different climate variants over the next 30 years have on the reliability of water supply (at the 70, 80 and 90% levels) across seven different agricultural zones in the Musi catchment in India. A hydro-economic modelling effort underlies these results (see Davidson et al forthcoming) which draws on a hydrologic analysis based on the Hadley climate model to model the surface and ground water in the catchment. This model then provides inputs into an allocation model (REALM), to assess the amount of water reliably supplied to different zones in the Musi catchment at different levels of reliability. These flows are ultimately valued to determine the economic consequences of different climate scenarios. In this study, the results are reported for four dryland regions (zones 1 to 4), an irrigation region (Musi Medium,) and two river diverters (the Musi Anicut and the Wastewater irrigation system). Unsurprisingly, from a physical perspective the region's most greatly affected are those heavily dependent on dryland agriculture, especially near Hyderabad City. This region is where the high value products (such as vegetables) are produced. These results imply that some caution should be exercised in choosing policies that allow for the adaptation of climate change, especially in the dryland zones.

Understanding future changes in crop water requirements and irrigation demand in the context of climate change is essential for long-term water resources management and agricultural planning. This study investigates the impacts of climate change on future water requirements of dry season Boro rice. Climate scenarios for four North-West districts of Bangladesh were constructed from the outputs of five global circulation models using a combination of statistical downscaling and bias correction. The generated climate data were used as input for CropWat to estimate water requirements of Boro rice for 2050s and 2080s (using 30 year average climate data). Reference crop evapotranspiration (daily ETo) is increasing in the future, mainly due to higher temperatures. Potential crop water requirement (∑ETC) of Boro rice, however, will reduce by 6.5% and 10.9% for RCP 4.5 and 8.5, respectively for 2050s; and by 8.3% and 17.6% for RCP 4.5 and 8.5, respectively for 2080s compared to the reference period (1980–2013). ΣETC will decrease because of a lower number of growing days due to the phenological response of rice to higher temperatures. Low rainfall accessibility under a shortened Boro season leads to an increase in the amount of irrigation water required to satisfy crop evapotranspiration demand. Although daily water requirements will increase, the total net irrigation requirement of Boro rice will decrease by 1.6% in 2050s and 7.4% in 2080s for RCP 8.5 scenario on average for all models and districts. Estimated net irrigation requirements showed high variations for different climate models, mainly due to a high variation in the projected rainfall. For improved water management planning, close monitoring and periodic evaluations are necessary to understand future directions of change in rainfall amounts and distribution.

The drought prone North-West Bangladesh is vulnerable to the impacts of climate change, particularly because of less water availability in the dry period and high water requirement for crop production. Improved understanding of recent changes in crop water demand in the dry season is important for the water resources management in the region. A study was carried out to determine the potential impacts of recent climate change during last three decades on trends of water requirements of Boro rice. The reference crop evapotranspiration (ETo), potential crop water requirement (∑ETC), effective rainfall during the crop growing period (ER), potential irrigation requirement for crop evapotranspiration (∑ETC − ER) and net irrigation requirement of Boro rice were estimated using observed daily climate data in the CropWat model for the period of 1980 to 2013 for four North-West districts. Significant decreasing trends of ETo were observed in most of the dry months due to increasing relative humidity and decreasing wind-speed and sun-shine hours. The results showed decreasing trends of potential crop water requirement, i.e. the total crop evapotranspiration (∑ETC), of Boro rice due to decreasing reference crop evapotranspiration and shorter crop growing periods. The variations in trends of potential irrigation requirement for crop evapotranspiration (∑ETC − ER) found among different districts, are mainly linked to variations in trends of changes in effective rainfall. The net irrigation requirement of Boro rice has decreased, by 11% during the last three decades at an average rate of −4.4 mm year−1, instead of decreasing effective rainfall, mainly because of high rate of decrease of crop evapotranspiration (−5.9 mm year−1). Results indicate that a warming climate does not always result in higher agricultural water use and that climate change can also result in reduced water demands because of changes in humidity, wind-speed and sun-shine hours.

A risk farmers have to cope with is annual changes in the availability of irrigation water. In this paper the relationship between irrigation water allocated to farmers and the incomes they derive in the Coleambally Irrigation Areas (CIA) in Australia is quantified. It is shown empirically that farmers reduce the area cropped when faced with reduced water availability. Increasing the availability of water does not necessarily lead to more stable (less volatile) income streams, as it offers the opportunity to include more water intensive, yet also more risky, crops in the cropping pattern (e.g. rice). However, it does lead to an overall increase in incomes. It was found that rice is the dominant crop for all levels of risk aversion, as shown by a stochastic dominance approach and by the stochastic efficiency with respect to a function. The optimal farm plan portfolio besides rice also includes a substantial amount of wheat if irrigators are somewhat risk averse, while more risk-averse farmers prefer more maize in their farm crop plans. The relative reduction in expected income from the optimal farm plan chosen, given a rather risk averse farmer, compared to the expected income of the optimal farm plan chosen by a risk neutral farmer, is approximately 9%.

Effective management of groundwater resources in a world where high-quality source water is becoming both physically and economically scarcer requires interdisciplinary collaboration among hydrologists, ecologists, engineers, and economists. This theme issue, Economics of Groundwater Management, seeks to further communication and cooperation across disciplines by presenting a collection of economic research articles that demonstrate a broad range of approaches used by economists to integrate hydrologic concepts into economic frameworks. The theme issue opens with an overview of the economic approach to groundwater management in Qureshi et al. Economists commonly define optimal groundwater management as the rate of extraction by location and time that maximizes the present value of net benefits (after deducting the costs from the gross benefits). Making the best use of limited groundwater resources requires a conceptual framework that defines best use combined with knowledge of alternate extractive and nonextractive values, the costs of extraction, the hydrological interlinkages between alternative uses, hydrological linkages with surface water, the cost of alternative water sources, and how policy and institutions influence outcomes. Hydrological models of quantity and quality are essential since maximization of net benefits is subject to the hydrological characteristics of the aquifer and related water sources. Incorporation of extraction and application technologies and costs, as well as structural solutions such as artificial recharge, require hydrological and irrigation engineering knowledge. Since economists broadly define benefits to include both extractive and non-extractive values, ecological modeling may be necessary for appropriate valuation. Furthermore, institutional and policy factors influence groundwater value and must be considered in concert with supply and demand.

This paper demonstrates that combining spatial land surface data with socio-economic analysis provides a number of indicators to strengthen decision making in integrated water and environmental management. It provides a basis to: track current water consumption in the Inkomati Basin in South-Africa; adjust irrigation water management; select crop types; facilitate planning; estimate crop yields before harvesting, and consequently to forecast market price development. Remote sensing data and economic analysis can also be used to study the spatial distribution of water consumption as an indicator of equity in access to water resources. It even enables identification of farms that consume more irrigation water than formally allocated. Finally, it provides a basis to assess the cost-effectiveness of various ways to reduce agricultural water consumption. So, this approach is potentially useful for determining water consumption, refining water allocation policies, and determining the potential for water transfers through mechanisms such as water trading.

The increasingly urgent reform of water allocation is challenged by the complexity of the political dimension, in particular the need to reconcile often competing objectives such as food and energy security and green growth. Moreover, these objectives are unstable, and allocation regimes have to adjust to shifting priorities and circumstances at the lowest cost to society. Climate change generates additional uncertainty in water availability and demand. This calls for robust allocation regimes that can adjust, reallocate and reduce water allocation in an organized way.

World financial support for Yemen has concentrated on improved irrigation technology as the primary means to reduce the rate of overexploitation of Yemen’s aquifers. An analysis of the impact of such investments on cumulative water abstraction, water savings and the life of an aquifer is presented. It shows that these investments have limited potential to extend aquifer life. The returns are highest in areas with significant remaining resources, and are not attractive in the most severely stressed areas. The analysis also shows that improved irrigation technologies increase the profitability of pumping for the farmer, exacerbating problems of over-abstraction. Finally, it shows that water savings depend on the hydrogeological situation. The policy implications of these findings are discussed in relation to Yemen, an exceptionally water-short country where most of the aquifers in groundwater-irrigated areas are severely over-drafted.

In this paper the residual method is used to determine the disaggregated economic value of irrigation water used in agriculture across crops, zones and seasons. This method relies on the belief that the value of a good (its price by its quantity) is equal to the summation of the quantity of each input multiplied by its average value. By applying this method to the Musi sub-basin; a subdivision of the Krishna basin in India, it was found that the value of irrigation water use is not equated across the crops, zones and seasons. The reasons why there is no sinlge value of irrigation water use are suggested. As farmers do not have perfect knowledge, do not all possess the same resource base, plant different crops for a variety of reasons (some for a financial return on land instead of water and others for sustenance), possess different crop rotation practices and are possibly riks adverse, they all value water differently. However, the results need to be interpreted with care as the crop with the lowest return to water is probably not the one to be sacrificed if water is restricted, since farmers plant crops for a variety of reasons (and sometimes not for the highest return to water that they can achieve).

Global water use for food production needs to be reduced to remain within planetary boundaries, yet the financial feasibility of crucial measures to reduce water use is poorly quantified. Here, we introduce a novel method to compare the costs of water conservation measures with the added value that reallocation of water savings might generate if used for expansion of irrigation. Based on detailed water accounting through the use of a high‐resolution hydrology‐crop model, we modify the traditional cost curve approach with an improved estimation of demand and increasing marginal cost per water conservation measure combination, adding a correction to control for impacts on downstream water availability. We apply the method to three major river basins in the Indo‐Gangetic plain (Indus, Ganges and Brahmaputra), a major global food producing region but increasingly water stressed. Our analysis shows that at basin level only about 10% (Brahmaputra) to just over 20% (Indus and Ganges) of potential water savings would be realized; the equilibrium price for water is too low to make the majority of water conservation measures cost effective. The associated expansion of irrigated area is moderate, about 7% in the Indus basin, 5% in the Ganges and negligible in the Brahmaputra, but farmers' gross profit increases more substantially, by 11%. Increasing the volumetric cost of irrigation water influences supply and demand in a similar way and has little influence on water reallocation. Controlling for the impact on return flows is important and more than halves the amount of water available for reallocation.