Hydrological Constraints Research Articles

Incorporating hydrological constraints with deep learning for streamflow prediction

Streamflow prediction is a fundamental task serving for flood prevention and efficient water resource management. Deep learning-based methods have emerged as the dominant approach and have made remarkable progress in the task. However, these methods ignore the hydrological constraints on streamflow, such as water delay time and streamflow direction, resulting in inaccurate prediction. To address this problem, this study incorporates hydrological constraints with deep learning models to improve streamflow prediction, and develops a hydrological constrained graph convolutional network (HCGCN) model. Specifically, the model designs a time-delayed spatiotemporal directed graph to present the spatiotemporal relationships and hydrological constraints, and develops a hydrological feature aggregation module to adaptively learn the complex spatiotemporal dependencies. In addition, HCGCN proposes a streamflow prediction neural network to predict streamflow by stacking the feature aggregation modules. Experimental results show that HCGCN significantly improves the prediction accuracy in a real streamflow prediction task. This study provides an exploration of introducing hydrological constraints to improve streamflow prediction, and provides a new reference for various hydrological prediction tasks.

Icings as sentinels and modifiers of water flow through winter landscapes: An exploration of physico‐chemical processes on the lake‐dominated, discontinuous permafrost Taiga Shield

AbstractThe winter hydrological period is in transition across the Canadian subarctic, as climate warming is shifting precipitation regimes, thawing permafrost, and altering active layer dynamics, and thus increasing the overall amount, and variability, of winter streamflow. Effects of these changes are poorly understood on the Taiga Shield, which comprises ~20% of North America's permafrost‐covered area, and is characterized by a unique ‘fill‐and‐spill’ hydrology whereby runoff generation requires the exceedance of lake basin storage thresholds. Here, we assessed lake hydrostatic levels and used trail camera images of icings, which are sheet‐like masses of layered ice that are common manifestations of wintertime flow on the Taiga Shield, to understand landscape controls on winter water movement in this region. We further used paired geochemical measurements to explore how source water characteristics affect icing chemistry, and the degree to which icings may modify the chemical composition of active winter flow. We undertake this work over 2 years, and across watersheds of different sizes and lake basin characteristics. We show that icing growth is driven by hydroclimatic controls that include fill‐and‐spill hydrologic constraints and winter air temperatures, and that pre‐freshet pulses of water flow are common within this landscape. Across winters with variable antecedent precipitation levels, a larger catchment was able to support icing growth via continued runoff generation, while small catchments were not. Icings were often chemically dilute compared with source waters, indicating that solute exclusion may actively enrich geochemical concentrations in flowing water. Across icings, chemical variation appeared related to source water type (groundwater versus lake; lake size) and apparent redox conditions. These results highlight that streamwater hydrology and biogeochemistry can be dynamic during the understudied winter period, and illustrate that icings may alter the composition of wintertime flow as it moves through fluvial networks.

Smart Lanceolate Surface with Fast Fog-Digesting Performance for Triboelectric Energy Harvesting.

Utilizing the ubiquitous fog in nature to create decentralized energy-harvesting devices, free from geographical and hydrological constraints, presents an opportunity to foster sustainable power generation. Extracting electrical energy from fog relies heavily on fog-digesting performance. Improving the efficiency of fogwater utilization remains a formidable challenge for existing fogwater energy-harvesting technologies. Inspired by the water-harvesting behavior of Tillandsia leaves, a smart lanceolate surface is developed to harvest triboelectric energy by rapidly digesting fog. Such a surface exhibits capabilities in fog management, encompassing precise fog capture, transportation, and critical droplet separation. Specifically, fog droplets condense at hydrophilic sites of acylated cellulose ester, subsequently migrating toward the rear under Laplace pressure, thereby producing energy as they traverse through the tail end. Such architecture yields a brief voltage restoration period (with an average of 9.36 s), can rush the capacitor to 11.59 V within 20 s, and achieves a water-digestion rate of up to 71.05 kg/m2 h. This biomimetic approach enhances the water-digestion efficacy of the atmospheric water energy apparatus and offers perspectives on mitigating deficiencies in power resources.

Hydrological constraints on the potential of enhanced geothermal systems in the ductile crust

Continental crust at temperatures > 400 °C and depths > 10–20 km normally deforms in a ductile manner, but can become brittle and permeable in response to changes in temperature or stress state induced by fluid injection. In this study, we quantify the theoretical power generation potential of an enhanced geothermal system (EGS) at 15–17 km depth using a numerical model considering the dynamic response of the rock to injection-induced pressurization and cooling. Our simulations suggest that an EGS circulating 80 kg s−1 of water through initially 425 ℃ hot rock can produce thermal energy at a rate of ~ 120 MWth (~ 20 MWe) for up to two decades. As the fluid temperature decreases (less than 400 ℃), the corresponding thermal energy output decreases to around 40 MWth after a century of fluid circulation. However, exploiting these resources requires that temporal embrittlement of nominally ductile rock achieves bulk permeability values of ~ 10–15–10–14 m2 in a volume of rock with dimensions ~ 0.1 km3, as lower permeabilities result in unreasonably high injection pressures and higher permeabilities accelerate thermal drawdown. After cooling of the reservoir, the model assumes that the rock behaves in a brittle manner, which may lead to decreased fluid pressures due to a lowering of thresholds for failure in a critically stressed crust. However, such an evolution may also increase the risk for short-circuiting of fluid pathways, as in regular EGS systems. Although our theoretical investigation sheds light on the roles of geologic and operational parameters, realizing the potential of the ductile crust as an energy source requires cost-effective deep drilling technology as well as further research describing rock behavior at elevated temperatures and pressures.

Isotopic and kinetic constraints on methane origins in Icelandic hydrothermal fluids

The origin of methane in hydrothermal fluids has long been a subject of debate – whether it is abiotic or biotic. In this study, we aim to unravel and quantify the sources of CH4 in active hydrothermal systems by adopting a holistic approach analyzing well characterized high-temperature hydrothermal fluids (∼230–310 °C) in Iceland. We employ a broad variety of geochemical and isotope indicators, encompassing chemical and isotope compositions of the targeted fluids. These signatures are then compared with results from chemical and isotope kinetic models and data from sedimentary-hosted hydrothermal systems. Carbon species in these fluids include CO2 (2.60–184 mmol/kg), CH4 (2.39·10−4–0.325 mmol/kg), dissolved organic carbon (4.78·10−3–0.112 mmol/kg), and CO (1.89·10−6–4.16·10−4 mmol/kg). Carbon and helium isotopes suggest a relatively uniform mantle-derived source of CO2 (δ13C-CO2: −4.80 to −1.50 ‰, CO2/3He: 1.49·109–4.14·1010 14C-CO2: 0.11–2.42 pMC). Methane, in contrast, has multiple sources. Overall, chemical equilibria among carbon species (CO2, CH4, CO) is not attained, suggesting kinetic controls. Tritium content (<0.8–1.42 TU) and hydrologic constraints indicate relatively short hydrothermal fluid residence times (∼5–200 years), with occasional inputs from older water components. Within this short timeframe, CH4 concentrations vary from lower, to significantly higher than those calculated using CO2 reduction kinetics. The isotope composition (δD-CH4: −172 to −138 ‰, δ13C-CH4: −32.0 to −24.6 ‰; 14C-CH4: 0.36–11.54 pMC) and geochemical and isotope modeling suggest that the majority (>80–90 %) of CH4 originates from a radiocarbon inactive source, i.e. mantle CH4, reduction of mantle CO2 and/or old organic matter, with relatively small contributions from both marine (<20 %) and terrestrial (<10 %) dissolved organic carbon. Measured isotopic compositions of CH4 do not match those expected for mantle-derived CH4 as well as values generated from reduction of mantle-derived CO2. Instead, differences in δD-CH4 and δ13C-CH4 values exist between systems fed by meteoric water and those fed by seawater, challenging the assumption of a uniform CO2 source and invariable reaction mechanisms. Differences between systems are best explained by variable extent of thermal decomposition and primary variations in the isotope composition of marine and terrestrial organic matter. Also, δD-CH4 and δ13C-CH4 values in meteoric water-fed systems closely resemble those in the Öxarfjördur sedimentary-hosted systems. In summary, our data supports a predominant thermogenic origin of CH4 in both seawater and terrestrial hydrothermal fluids in Iceland. The source of organic matter appears to be a combination of modern dissolved organic carbon and older sedimentary deposits. In addition, some of the hydrothermal systems studied (Krafla, Reykjanes, Theistareykir) which are characterized by low CH4 concentrations, may contain a significant portion of CH4 that may originate from CO2 reduction.

Anthropogenic Weakening of the Atmospheric Circulation During the Satellite Era

AbstractClimate models predict a slowing of the atmospheric overturning circulation with warming. In models, this slowing manifests primarily as a weakening of the Walker Circulation (WC). However, observational studies indicate a strengthened Pacific WC over the past several decades, raising questions about the models' ability to represent critical energetic and hydrologic constraints responsible for the predicted weakening. This discrepancy is closely tied to differences in the warming pattern over the Pacific during this period. We show that model simulations with either observed or model‐projected warming patterns predict a robust weakening of atmospheric overturning circulation, despite having opposing changes in the Pacific WC strength. This weakening occurs in the zonally asymmetric circulation, rather than in the zonal‐mean Hadley cell. Weakening inferred from satellite observations is reproduced in coupled models only when anthropogenic forcing is included, suggesting that a human‐induced weakening of the global atmospheric circulation is already detectable in observations.

Interpreting effective hydrologic depth estimates derived from soil moisture remote sensing: A Bayesian non-linear modeling approach

The water balance equation (WBE) describes how net water inflows into a system relate to storage changes over a time span (dt). This equation is fundamental in hydrologic studies, helping to determine water supply and elucidate the terrestrial water cycle. For land surface, the WBE links water fluxes like precipitation (P), evapotranspiration, drainage and surface runoff to soil moisture (SM) changes within a discrete soil layer (dSM). While traditional focus has been on the precision of the WBE-estimated fluxes, there has been increased recent interest in fitting the WBE using remotely-sensed P and SM data to infer water balance parameters, particularly the ΔZ that associates net fluxes and dSM within dt. However, obtaining physically interpretable WBE parameters like ΔZ is a potentially ill-posed problem due to simplifying assumptions imbedded in a WBE implementation, missing hydrologic constraints, and accuracy and revisit limitations in available remotely-sensed data. In addition, WBE parameters obtained from classical maximum likelihood estimation approaches can vary significantly. Here, using a Bayesian non-linear modeling approach, we demonstrate how these factors can impede the identification of useful ΔZ estimates. Specifically, we find that ΔZ estimates are likely to be spuriously biased due to limitations in the temporal resolution and accuracy of satellite-based dSM estimates – as well as the neglect of other hydrological components in the WBE. Maps showcasing the lower and upper bounds of the 94 % HDI from our Bayesian model further elucidate these biases. Results suggests that estimates of ΔZ are effective in nature and great care should be exercised when attempting to interpret them physically. Instead, they should be defined as effective parameters reflecting the characteristics of their fitted remotely-sensed data sets. Drawing from current progress, accurate ΔZ estimates, informed by more advanced remote sensing techniques and precise WBE, will enhance our understanding of terrestrial water cycle.

Wetscapes: Restoring and maintaining peatland landscapes for sustainable futures.

Peatlands are among the world's most carbon-dense ecosystems and hotspots of carbon storage. Although peatland drainage causes strong carbon emissions, land subsidence, fires and biodiversity loss, drainage-based agriculture and forestry on peatland is still expanding on a global scale. To maintain and restore their vital carbon sequestration and storage function and to reach the goals of the Paris Agreement, rewetting and restoration of all drained and degraded peatlands is urgently required. However, socio-economic conditions and hydrological constraints hitherto prevent rewetting and restoration on largescale, which calls for rethinking landscape use. We here argue that creating integrated wetscapes (wet peatland landscapes), including nature preserve cores, buffer zones and paludiculture areas (for wet productive land use), will enable sustainable and complementary land-use functions on the landscape level. As such, transforming landscapes into wetscapes presents an inevitable, novel, ecologically and socio-economically sound alternative for drainage-based peatland use.

Multidisciplinary assessment of the agricultural supply of desalinated seawater in south-eastern Spain

Desalinated seawater (DSW) has provided a steady supply of agricultural water for the last decade in south-eastern (SE) Spain, overcoming climatological and hydrological constraints. This article analyses the impacts of the progressive replacement of traditional irrigation water resources with DSW on the main crops of SE Spain, from agronomic, environmental, and economic perspectives, for the first time. The regional magnitude and spatial variability of these impacts have also been evaluated. To that end, six impact indicators were identified and calculated for three water supply scenarios using increasing proportions of DSW, which is representative of the current and possible future situations.The results reflect the high variability of the impact indicators for the different crops. The agronomic impact is favourable but the benefits of reducing water salinity become saturated when DSW exceeds 50 %. The detrimental environmental impact is due to the higher specific energy consumption associated with increased DSW supply, although this is not an intrinsic problem of seawater desalination since it could be mitigated using renewable energies. The economic impact is very sensitive to the cost of DSW and offers heterogeneous results for the different crops. The results show that the combined use of DSW with traditional resources is the most efficient option from the different perspectives of the study, rather than irrigating with DSW alone. The insights from this study could be useful for the assessment of the feasibility of integrating DSW to support agriculture in other regions where desalination plants are being considered to support the water supply.

Improved Surface Mass Balance Closure in Ocean Hindcast Simulations

AbstractForced global ocean/sea‐ice hindcast simulations are subject to persistent surface mass flux estimation biases, for example, configurations with an explicit‐free surface may not take into account the seasonal storage of water on land when constraining sea level. We present a physically motivated surface mass flux closure, that results in: reduced watermass drift from initialization; improved Atlantic meridional overturning cirulation intensity; and more realistic rates of ocean heat uptake, in simulations using global ocean/sea‐ice/land (MOM6/SIS2/LM3) model configurations, forced with atmospheric reanalysis data. In addition to accounting for the land storage, the area‐integrated subpolar‐to‐polar (40°–90°N/S) surface mass fluxes are constrained, using a climatological estimate derived from the the CMIP6 historical ensemble, which helps to further improve hindcast performance. Simulations using MERRA‐2 and JRA55‐do forcing, subject to identical hydrologic constraints, exhibit similar reductions in drift.

Hydrological implications of large-scale afforestation in tropical biomes for climate change mitigation.

Rising interest in large-scale afforestation and reforestation as a strategy for climate change mitigation has recently motivated research efforts aiming at the identification of areas suitable for the plantation of trees. An often-overlooked aspect of agroforestry projects for carbon sequestration is their impact on water resources. It is often unclear to what extent the establishment of forest vegetation would be limited by water availability, whether it would engender competition with other local water uses or induce water scarcity. Here we use global water models to study the hydrologic constraints and impacts of afforestation in tropical biomes. We find that 36% of total suitable and available afforestation areas are in areas where the rain alone can meet just up to the 40% of total plant water requirement. Planting trees will substantially increase water scarcity and possible dispossession (green water grab) especially in dryland regions of Africa and Oceania. Moreover, the combination of tree restoration and irrigation expansion to rainfed agricultural areas is expected to further exacerbate water scarcity, with about half of the global suitable areas for tree restoration experiencing water scarcity at least 7 months per year. Thus, the unavailability of water can overall limit climate change adaptation strategies. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'.

Available water capacity of sandy soils as affected by biochar application: A meta-analysis

Sandy soils have inherently low available water capacity (AWC), making their use for agricultural production a challenging task. Biochar amendments have been recommended to enhance the hydrological properties of sandy soils. A meta-analysis of existing literature was conducted to investigate the overall effect of biochar on the AWC of sandy soils. Key factors related to biochar characteristics (specific surface area, particle size, carbon content) and production conditions (pyrolytic temperature, feedstock), soil properties (pH, textural class, organic carbon content), and experimental setting and duration were also included in the analysis. Sandy soils amended with biochar had their AWC significantly increased, on average, by 28.5% compared to un-amended soils. Biochar had no significant effect on AWC when it had a large particle size (PS > 5 mm) or when applied to soils with high carbon content (SOC > 2%). No significant changes in AWC were found among biochar feedstocks, pyrolytic temperatures, and specific surface areas. Available water capacity was higher due to the application of biochar with fine PS compared to coarse PS and with low C (C < 50%) than high C (C > 70%) content. The increase in AWC in biochar-amended sandy soils was most pronounced in those with the highest sand content, acidic pH, and the lowest C content. Our analysis further showed that the effects of biochar application on AWC were greater under controlled laboratory conditions compared to field trials and in short-term rather than in long-term experiments. Overall, the current meta-analysis revealed that biochar technology has the potential to contribute towards the alleviation of the hydrological constraints of sandy soils leading to more drought-resistant soils in the face of an expected dryer climate.

Seasonal drought and its effects on frog population dynamics and amphibian disease in intermittent streams

AbstractChytridiomycosis, caused by the pathogenic fungusBatrachochytrium dendrobatidis(Bd), has contributed to amphibian declines globally, but drivers of outbreaks vary locally. Here, we explore the role of drought in population and host‐disease dynamics of the endangered stream‐breeding foothill yellow‐legged frog (Rana boylii). In central California (USA) where severity of seasonal drought is increasing, we observed the non‐native, Bd‐tolerant and lentic‐adapted North American bullfrog (Lithobates catesbeianus) extend into streams when flood disturbance was minimal. Analysis of skin swabs revealed that prevalence and load of Bd infection among bullfrogs was low. Yet, among the native frogs, prevalence and load intensified as the seasonal drought progressed and surface flow became intermittent. When temperatures decreased in autumn and frogs concentrated at a reduced number of water points, we found dozens of dead foothill yellow‐legged frogs (2018–2019). Necropsies suggested chytridiomycosis as the likely cause of death. Despite recent lethal outbreaks, foothill yellow‐legged frog population abundance appeared resilient based on comparison to prior decades when no die‐offs were observed. Wet–dry mapping of the stream channel and retrospective analysis of hydrologic records revealed that the native frogs spawn away from perennial pools, a behaviour that may allow them to avoid bullfrogs and predatory fish. In an ecological trade‐off, tadpoles face the risk of the stream drying before metamorphosis. Fluctuations in population size thus corresponded to extremes of inter‐annual variation in streamflow that limit recruitment rather than disease outbreaks. We conclude that hydrologic constraints, which climate change may exacerbate, appear to override the stressors of non‐indigenous species and chytridiomycosis.

Advancing the representation of reservoir hydropower in energy systems modelling: The case of Zambesi River Basin.

In state-of-the-art energy systems modelling, reservoir hydropower is represented as any other thermal power plant: energy production is constrained by the plant's installed capacity and a capacity factor calibrated on the energy produced in previous years. Natural water resource variability across different temporal scales and the subsequent filtering effect of water storage mass balances are not accounted for, leading to biased optimal power dispatch strategies. In this work, we aim at introducing a novelty in the field by advancing the representation of reservoir hydropower generation in energy systems modelling by explicitly including the most relevant hydrological constraints, such as time-dependent water availability, hydraulic head, evaporation losses, and cascade releases. This advanced characterization is implemented in an open-source energy modelling framework. The improved model is then demonstrated on the Zambezi River Basin in the South Africa Power Pool. The basin has an estimated hydropower potential of 20,000 megawatts (MW) of which about 5,000 MW has been already developed. Results show a better alignment of electricity production with observed data, with a reduction of estimated hydropower production up to 35% with respect to the baseline Calliope implementation. These improvements are useful to support hydropower management and planning capacity expansion in countries richly endowed with water resource or that are already strongly relying on hydropower for electricity production.

Open Science Practices for Studies of Event-Related Potentials (ERPs): Reporting ERP Reliability and Data Quality in the Spirit of Transparency

Hydrological frequency analysis (HFA) is commonly used for the assessment of the risk associated to hydrological events. HFA is generally based on the assumptions of homogeneity, independence and stationarity of the hydrological data. Hydrological events are often described through a number of dependent characteristics, such as peak, volume and duration for floods. Unfortunately, in this multivariate setting, the verification of the above assumptions is often neglected. When a shift occurs in a data series, it can affect the stationarity and the homogeneity of the data. The objective of this paper is to study tests for shift detection in multivariate hydrological data. The considered shift tests are mainly based on the notion of depth function, except for one test that is considered for comparison purposes. A simulation study is performed to evaluate and compare the power of all these tests with hydrological constraints. A flood analysis application is also carried out to show the practical aspects of the considered tests. The power of the considered tests is influenced by a number of factors, including the sample size, the shift amplitude, the magnitude of the series and the location of the shift in the series.

Anatomical adaptations in aquatic and wetland dicot plants: Disentangling the environmental, morphological and evolutionary signals

Understanding how plants adjust their internal structures to withstand adverse environmental conditions is vital for predicting their responses to ongoing environmental change. Plants have repeatedly evolved small water transporting conduits and large storage parenchyma tissues to cope with anoxia, freezing- or drought‐induced damages. However, how these adaptations evolved in unrelated taxa across hydrological and thermal gradients, remains unclear. Here we show that stem anatomical variations in 212 European aquatic and wetland dicots are driven by thermal and hydrological constraints via control over plant size, growth form, and leaf traits, while phylogenetic constraints have only a weak effect. Phylogenetic comparative analyses controlling for confounding factors showed that both waterlogging (anoxia) and low-temperature promote smaller plants with reduced vessel conduits and limited lignification, but extended parenchyma and hence storage and tissue renewal capacity to secure resilience to biomass loss induced by running water or frost disturbances. Decreasing water depth and anoxia promote larger wetland plants with thick-walled libriform fibers, large vessels with simple perforation plates securing high hydraulic efficiency, and semi-ring porous xylem with wide earlywood vessels in spring and narrow latewood vessels in summer, providing both efficiency and safety in water transport. The aquatic environment promotes plants with a large cortex zone with photosynthetic chlorenchyma and starch-storing parenchyma cells along with extensive air spaces that provide aeration and buoyancy. Low temperatures promote short-stature forbs with smaller vessels, scalariform perforation plate, extended parenchyma, resulting in reduced embolism risk. Although most anatomical variation was explained by differences between aquatic and wet terrestrial growth forms, environmental gradients, plant size, and leaf properties exerted a significant control on plant tissue structures not confounded by phylogenetic inertia. Distinct habitats, spread across broad thermal and hydrological gradients, harbor unrelated species with different evolutionary histories that have converged to similar anatomical and hence morphological structures.

A satellite-driven hydro-economic model to support agricultural water resources management

The management of water resources among competing uses presents a complex technical and policy challenge. Integrated hydro-economic models capable of simulating the hydrologic system in irrigated and non-irrigated regions including the response of farmers to hydrologic constraints and economic and policy incentives, provide a framework to understand biophysical and socioeconomic implications of changing water availability. We present a transformative hydro-economic model of agricultural production driven by multi-sensor satellite observations, outputs from regional climate models, and socioeconomic data. Our approach overcomes the limitations of current decision support systems for agricultural water management and provides policymakers and natural resource managers with satellite data-driven, state-wide, operational models capable of anticipating how farmers allocate water, land, and other resources when confronted with new climate patterns, policy rules, or market signals. The model can also quantify how farming decisions affect agricultural water supplies. We demonstrate the model through an application in the state of Montana.

Prediction of CO₂ Saturation Spatial Distribution Using Geostatistical Inversion of Time-Lapse Geophysical Data

Carbon dioxide sequestration in deep saline aquifers and depleted reservoirs relies on numerical models for the prediction of the spatial distribution of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> saturation during injection and migration. Due to the limited knowledge of the rock and fluid properties before injection, model predictions are often uncertain and must be updated when new measurements are available. The spatial distribution of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> saturation and the plume location can be monitored using time-lapse geophysical data, such as seismic and controlled source electromagnetic surveys. We propose a geostatistical inversion approach for the prediction of the time-dependent spatial distribution of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> saturation from geophysical data. The methodology is based on the application of a stochastic optimization method, the Ensemble Smoother, for the solution of the inverse problem, using rock physics and geophysical models. The inversion is applied to the difference in the geophysical data acquired before and during injection. The predicted models of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> saturation are obtained by updating an ensemble of geostatistically generated prior realizations, based on the misfit between geophysical model predictions and measured data. The novelty of the approach is the integration of geostatistical algorithms and stochastic optimization methods for the joint inversion of geophysical data. The proposed approach allows including hydrological constraints in the prior model and quantifying the prediction uncertainty due to the noise and resolution of the data and approximations in the physical relations. The method is applied to the Johansen formation model, offshore Norway, using synthetic seismic and electromagnetic data.

Why (Not) Desalination? Exploring Driving Factors from Irrigation Communities’ Perception in South-East Spain

Desalination for sustaining agricultural production is conceived as an alternative water source in some Mediterranean countries faced with climatological and hydrological constraints. Although high costs are often cited as limiting factors, how farmers discern desalinated water has not been discussed in-depth in the literature. This paper aims to deepen how desalination is perceived by irrigators, what driving factors are affecting irrigation communities’ decision-making processes, and what learnings can be drawn from their experiences regarding desalination acceptance or rejection. Eleven irrigation communities have been selected from Alicante and Murcia regions (South-East Spain), which account for more than 60,000 irrigators and 120,000 ha. Questionnaires were conducted between March and December 2019. Results highlighted the main advantages (water availability and supply security) and disadvantages (high price affecting profitable crop options, high-energy consumption, water quality standards, the production capacity of desalination plants, no seasonal variation in water production, and shortages due to technical problems) of using desalinated water. Additionally, through the analysis of regional and national press news, it can be concluded that socio-political aspects, such as corruption, cost overruns, and political disputes are also considered.

Assessing concerns about fertigation costs with desalinated seawater in south-eastern Spain

Desalinated sea water (DSW) provides a steady agricultural water supply that overcomes climatological and hydrological constraints, fostering food security and socio-economic stability in water-stressed regions. In the last decade, seawater desalination for irrigation has been massively implemented in south-eastern (SE) Spain amid rising pressure and competition for water resources. However, farmers seem reluctant to replace conventional water sources with DSW due to its higher price and the need for additional fertilization. This article assesses how fertigation cost increases can affect farming profitability when integrating DSW for irrigation. The increases in water and fertilizer costs of totally (100 %) and partially (50 %) replacing conventional water with DSW were calculated for the most representative crops of the Segura basin in SE Spain.The results show that the total replacement of conventional resources implies a fertigation cost increase equivalent to 3.2–35.5% of the crop production costs. However, replacing only 50 % of the conventional resources reduces these figures by more than half (1.5–15.7%). This supra-linear decrease comes from the fact that although water blending halves the water cost increase, the fertilizer cost increase is reduced by more than half. Looking at the fertigation cost increase relative to crop profit, remarkable profitability losses were observed for all crops in the total replacement scenario (21.6–129.1%), which only fell to more acceptable levels in the partial replacement scenario (10.3–57.1%). In the scenario with 100 % DSW, the estimated revenue increase required to compensate for the increase in the fertigation cost seems unrealistic for traditional crops (>15 % for melon and >25 % for lemon) whereas substantially more moderate increases are demanded from all crops (<10 %) when only 50 % DSW is used. Overall, this study stresses the need to properly evaluate water blending options to maintain agricultural profitability.