Water Management Decisions Research Articles

Geographic information systems as an innovative method for increasing the productivity of agricultural land

The goal is to identify and specify the stages of formation and development of geographic information systems (GIS) in agriculture, used to improve the efficiency of agricultural land. Methods – system analysis, monographic, statistical, economic, classification, grouping, logical generalization. Results – the author shows the problems of disseminating technologies that are geographically linked in the agricultural sector abroad and in Kazakhstan. The stages of cartography, remote sensing of the earth, organizational work to collect information on the biodiversity of the territory of foreign countries, starting from laboratories, then computer programming until the end of the cycle are outlined. Natural and climatic factors that influence the composition and change in the size of the land fund of the republic, in particular agricultural lands, are considered. Negative land management processes, the presence of a large amount of disturbed land resulting from industrial production, and the existence of anthropogenic pollution that worsen soil fertility are highlighted. Conclusions – the need for wide dissemination of GIS for the rational use of land resources arose during the monitoring and assessment of soil characteristics, the need to determine the forecast level of yield, water management, spatial planning and production decision-making. The argument for the use of GIS technologies is the modern land policy of the state, aimed at creating a rational balance between the sustainable development of the agroindustrial complex and the preservation of natural potential in order to improve living conditions in rural areas. Geographic information systems contribute to increasing the profitability of agricultural enterprises and optimizing its costs. Digital cartographic products are increasingly found in the practice of intensively developing farms.

Nature reserves (zapovedniks) in the Volga catchment: protection, research and management

AbstractIn the Russian Federation, the protection category “Zapovednik” represents a strictly protected area, where the access is restricted and the aim is to keep the area “forever wild”. We provide an overview about the organization of these nature reserves and highlight their contribution to fundamental research. Aquatic ecosystems in zapovedniks provide pristine sites of great importance for long-term monitoring and research, which fosters process understanding regarding interannual variability and development of aquatic coenosis. We present a long term monitoring and research project about abiotic and biotic parameters in the Central Forest State Nature Biosphere Reserve. Examples from the Privolzhskaya Lesostep Nature Reserve include monitoring of invasive fish as well as analyses about the influence of beavers on fish. The Astrakhan Biosphere Nature Reserve in the Volga delta is a hotspot for fish biodiversity; thus, there the state nature reserve security service plays an important role to avoid poaching. Our case studies from the Volga Basin exemplify the structure and function of nature reserves and highlight their contribution to research, protection and management of aquatic ecosystems. Long-term datasets from the zapovedniks can (i) improve process understanding, (ii) ensure protection of aquatic systems and sustainable water management and (iii) support knowledge-based decisions.

Groundwater hydrogeochemical assessment in and around the northern part of the Chennai city, South India

In the present study, 50 groundwater samples from the bore wells and tube wells, were collected in North Chennai, Tamil Nadu, India during the premonsoon (June 2021) and postmonsoon (January 2022) seasons and their physicochemical properties were assessed. The majority of the physicochemical characteristics with the exception of electrical conductivity (EC), total dissolved solids (TDS), sodium (Na+), chloride (Cl-) and sulphate (SO42-) were determined to be within the world health organization (WHO) standards for drinking water. The water quality index (WQI) was assessed and given one of six categories, from excellent to unfit for consumption. Gibb's plots showed that evaporation was the dominating type, while Piper and Chadha models predominantly showed sodium-chloride (Na-Cl) kinds. The interaction of freshwater and seawater has been observed through an ionic ratio analysis. In accordance to a groundwater quality research conducted in the study region, practically in all the sample locations, the levels of standard plate count (SPC) total coliforms (TC) bacterial contamination were higher than the acceptable guidelines (WHO). Water management and treatment policy decisions can be made with the support of water quality analysis which can also help to identify potential health issues.

Real-time reservoir operation using inflow and irrigation demand forecasts in a reservoir-regulated river basin

Real-time reservoir operation using inflow and irrigation demand forecasts can help reservoir system managers make effective water management decisions. Forecasting of inflow and irrigation demands is challenging, owing to the variability of the weather variables that affect inflows and irrigation demands. In this context, bias-corrected Global Forecasting System (GFS) forecasts are used here in a hybrid approach (reservoir module with Long Short Term Memory (LSTM)) to forecast the reservoir inflows. Concurrently, the bias-corrected GFS forecasts are used in irrigation demand module to forecast the irrigation demands. The ‘Scaled Distribution Mapping’ method is used to bias-correct the GFS data of 1–5 days lead. The study area is the Damodar river basin, India, consisting of five major reservoirs: Tenughat and Konar located upstream of Panchet, and Tilaya situated upstream of Maithon. With the upstream reservoir outflow forecasts, the inflows are forecasted in Panchet and Maithon reservoirs with NSE values of 0.88–0.96 and 0.78–0.88, respectively, up to a 5-day lead. The irrigation demand module with bias-corrected GFS forecasts forecasted the irrigation demands close to the irrigation demands with the observed weather data. The percentage errors in irrigation demand forecasts of the Kharif (June–October) season at 1–5 days lead are 9.45 %, −15.45 %, −20.52 %, −26.36 %, −27.31 %, respectively. On the contrary, percentage errors in irrigation demand forecasts of Rabi (November–February) and Boro (January–May) are in the range of 8.17–8.79 % and 3.48–8.06 %, respectively. With the inflows and irrigation demand forecasts, the Panchet and Maithon reservoirs satisfied the downstream demands and reduced the floods. The inflow and irrigation demand forecasts, based on the GFS forecasts, have substantial potential for real-time reservoir operation, leading to efficient water management downstream.

Exploring deficit irrigation as a water conservation strategy: Insights from field experiments and model simulation

Deficit irrigation has emerged as a viable approach to increase agricultural water productivity. The objectives of this study were to 1) develop water conservation strategies by investigating responses of green bean (Phaseolus vulgaris) and sweet corn (Zea mays var. saccharata) to four irrigation treatments and 2) evaluate the performance of the Decision Support System for Agrotechnology Transfer (DSSAT) model in simulating growth and yield responses of green bean and sweet corn under four irrigation treatments. A field experiment was conducted using 32 experimental plots, established under a linear move sprinkler irrigation system equipped with variable rate irrigation (VRI) technology, at the Tropical Research and Education Center (TREC), Homestead for two cropping seasons between November and March in 2020–2021 and 2021–2022. The experiment involved four irrigation treatments: full irrigation (FI) (T4), and three levels of deficit irrigation, 75% FI (T3), 50% FI (T2), and 25% FI (T1) with four replications arranged in a completely randomized block design (RCBD) for each crop. The average soil moisture content of the full irrigation treatments was maintained above the management allowable depletion (MAD). Field data collection included various parameters of the crops including plant phenology, plant height, canopy width, fresh and dry biomass, and yield. Results confirmed that all three deficit irrigation treatments did not significantly affect the yield and yield components of the two crops during both seasons compared to the T4. This finding revealed that the highest crop water productivity was achieved from T1, 38.3 and 41.4 kg m−3 for green bean and 54 and 53 kg m−3 for sweet corn during the 2020–2021 and 2021–2022 seasons and up to 75% irrigation water saving could be achieved without affecting plant growth and yield. The DSSAT model performed well in simulating yield and yield components for the two crops in response to the four irrigation treatments. Model evaluation results showed that the minimum mean absolute error (MAE) for green bean fresh pod yield simulation was 2.1 Mg ha−1 with an index of agreement (d-Stat) of 0.6, while for biomass, it was 0.24 Mg ha−1 with a d-Stat of 1. Similarly, for sweet corn, the model simulated fresh cob yield with a minimum MAE of 6.51 Mg ha−1 and d-Stat of 0.9 and biomass with MAE of 1.63 Mg ha−1 and d-Stat of 0.9. Overall, implementing deficit irrigation in green bean and sweet corn fields could result in considerable water savings while achieving acceptable crop yield. The DSSAT model could be also a useful tool to simulate green bean and sweet corn responses to different irrigation scenarios and aid water management decisions under South Florida conditions.

Development of Upper Euphrates Basin hydro-economic model and hydropower generation optimization

Abstract Hydro-economic optimization models are common in hydropower reservoir modeling to aid system operators and planners. In these models, operations are driven by the economic value and constrained by the availability of water. The objective is to either minimize total costs or maximize total benefits. In this study, a hydro-economic optimization model for the integrated reservoir system of the Upper Euphrates Basin, with major tributaries providing water flow to the Euphrates River, is introduced. These model the 10 large-scale reservoirs of the basin with a total installed capacity of 3,255 MW. Water management and hydropower decision-making operations are evaluated with a piecewise linear programming algorithm in monthly time steps using a 45-year historical hydrology between 1971 and 2016. The model aims to maximize hydropower revenue over a long-term time horizon with energy prices varying by month. Reservoir storage and turbine release decisions are optimized for multiple hydropower plants connected in serial or parallel. Hydropower generation, revenue, reservoir storage, capacity ratios and generation reliability results are analyzed. Results show that these hydropower plants generate about 9,481 Gigawatt hour (GWh) of energy with an average turbine capacity use of 36% and obtain a revenue of 620 million $ per year.

Coping with Complexity in Water Management: Lessons from Palestine

In this article, I examine the role of applied anthropology in coping with common water management dilemmas and in facilitating more equitable water management. Field research and interviews with Palestinian residents and water managers between 2012–2020 illuminate deep disagreements about two commonly used management tools: full-cost recovery pricing reforms and supply expansion through emerging water technologies. This case demonstrates that not only are there limits to the transportability of solutions across societies, but even within a society and among seemingly similar stakeholders, fundamental disagreement exists about a place’s water priorities and proper interventions. How do we explain the multiplicity of ways in which people seemingly of the same social group approach a single water issue? The article demonstrates an anthropological approach to understanding water use that draws political ecology’s focus on power together with attention to the intersectionality of peoples’ relationships to water. This approach can help water managers acknowledge the political impacts of purportedly apolitical management approaches, and it provides the basis for a more robust incorporation of diverse residents’ priorities into water management decision making.

Saltwater Intrusion Impacts Microbial Diversity and Function in Groundwater Ecosystems

Background: Groundwater ecosystem services provided by microbial communities are essential for the maintenance of water quality. For example, nitrate contamination is a recognised health and ecosystem issue in most groundwater systems, often alleviated through microbial processes. The effects of climate change, including increasing salinity from rising sea levels, or over-abstraction, on these communities are largely unknown. Methods: This study uses a combination of culture-dependent (growth curves, isolation of bacteria) and culture-independent (16S rRNA gene sequencing) methods to identify the potential effects of saltwater intrusion on groundwater microbes and their ecosystem functions. Results: Some groundwater microbial communities are negatively impacted by increasing chloride concentrations, including declines in bacteria responsible for nitrate and ammonia removal. These ecosystems should be prioritised for future protection from sea level rise or increased extraction of groundwater for agriculture and other uses. Other microbial communities are stimulated in the presence of chloride, often caused by an increase in abundance of salt-tolerant heterotrophic bacteria using sugars, peptides, or organic acids for energy. Conclusion: There have been no previous studies investigating the impact of chloride on Aotearoa New Zealand groundwaters. The identification of keystone species that are affected by increasing salinity, which have a disproportionately large effect on the ecosystem and low functional redundancy, is essential. Water management decisions about future abstraction limits and defences against sea level rise can be underpinned by robust scientific knowledge about microbial community sensitivity to salinity.

The effects of temperature and flooding duration on the structure and magnitude of a floodplain prey subsidy

Abstract Riverine floodplains serve as an important link between terrestrial and aquatic systems, as the rising and falling of water drive spatial food web subsidies that are critical to the functioning and stability of ecosystems. As these systems are increasingly impacted by hydrological alterations and climate change, it is important to understand how floodplain spatial food web subsidies may respond to changing environmental conditions. Here, we examine the interannual variation in the structure of a sunfish (Lepomis spp.) prey subsidy from freshwater marshes into the mangrove‐lined creeks of Rookery Branch in the Florida Coastal Everglades that occurs during seasonal dry downs. We evaluate how the structure of this subsidy relates to prior temperature and hydrological regimes based on a 16‐year electrofishing dataset. We also characterise the intra‐annual relationship between marsh water depths and sunfish migration patterns that underlie this subsidy. We found that interannual variation in the abundance and diversity of the sunfish prey subsidy was best explained by the minimum water temperature occurring within 90 days prior to peak abundance sampling periods, with lower minimum water temperatures associated with higher sunfish abundance and diversity. In contrast, interannual variations in the biomass of the sunfish prey subsidy were positively related to marsh flooding duration over 30 cm depth during the prior wet season. Intra‐annual models estimated peak sunfish abundance and biomass values in riverine habitats to occur during the transition between wet and dry periods when marsh depths are between 10 and 15 cm. Multivariate analysis of community abundance and biomass composition revealed that minimum water temperatures played an important role in structuring the prey subsidy, while the effect of flooding duration was weak. These results provide important insight into how floodplain prey subsidies may be altered under future climate and hydrological regimes and inform ecosystem‐based water management decisions.

Soil hydraulic properties and field-scale hydrology as affected by land-management options

Recurring puddling for long-term rice cultivation forms a plow pan at a particular soil depth, which alters soil hydraulic properties, field-scale hydrology, and nutrient persistence in the soil. This experiment aimed to assess the impact of long-term rice cultivation on root-zone soil hydraulic properties and field-scale hydrology. Soil core samples were collected from four land management options namely, rice‒rice, non-rice, rice and non-rice, and field ridge, at two sites, one with loam and another with silt-loam soil. The soil cores were sampled for each 10 cm layer up to 100 cm depth from three locations of each rotation at both sites. Soil hydraulic parameters were estimated using a pedotransfer function based on the measured bulk density and soil texture. A mathematical model named HYDRUS-1D predicted infiltration, percolation, and surface runoff with the estimated hydraulic properties for three extreme rainfall events, i.e., 3.33, 5, and 6.66 cm hr<sup>-1</sup>, during a 3-hour period. A plow pan was found at 20–30 cm soil depth for all the land management options but not for the field ridge. The plow pan of the rice‒rice rotation had the highest bulk density (1.53 g cm<sup>-3</sup>) and the lowest hydraulic conductivity (17.56 cm day<sup>-1</sup>). However, the top 10 cm soil layer in the rice–rice field had the lowest bulk density (0.93 g cm<sup>-3</sup>). At both sites, the field ridge had higher infiltration and percolation and lower runoff than other rotations. The study reveals that the field-ridge area of a rice field can be the main water loss pathway. Phosphorus concentration in the rice-rice rotation decreased from 7.7 mg kg<sup>-1</sup> in the 10-cm soil layer to 2.49 mg kg<sup>-1</sup> in the 100-cm layer. These findings will facilitate making better water management decisions.

Improving small watersheds socioeconomic indicators with nighttime light satellite data to support water management decisions

Small watersheds lack socioeconomic data. These data are essential in land use decision-making and in water resources management, especially when determining its economic value. In order to contribute to filling this notable gap, this study presents an approach to estimate this type of information for small watersheds (from 5 to 100 km²), applying nighttime light (NTL) satellite images and available socioeconomic records from larger locale. Three socioeconomic indicators were chosen to test the method: Gross Domestic Product, population and jobs. The relationship between these three socioeconomic indicators and the radiance quantified from the NTL images was acquired through simple regression analysis applied at the 497 municipalities of the State of Rio Grande do Sul (RS), southern Brazil. The polynomial fit equations presented the best Coefficient of Determination, being further submitted to validation by using data from 50 municipalities of the neighboring State of Santa Catarina. The validation showed a very good estimation performance. The validated equations were used to estimate these socioeconomic indicators for small watersheds located in the municipality of Caxias do Sul, RS, in three different years: 2011, 2014 and 2018. Findings indicate that this novel application of NTL for estimating socioeconomic data can be a helpful tool towards land use and water resources management of small watersheds.Keywords: GDP, population, job, nighttime light, water resources management. Estimando indicadores socioeconômicos de pequenas bacias hidrográficas através de imagens noturnas de satélite no apoio à gestão dos recursos hídricos R E S U M OHá falta de dados socioeconômicos para pequenas bacias hidrográficas. Esses dados são fundamentais para a tomada de decisões na gestão dos recursos hídricos, principalmente na determinação do seu valor econômico. Para contribuir em preencher essa lacuna, este estudo apresenta um método para estimar esse tipo de informação para pequenas bacias hidrográficas (de 5 a 100 km²), aplicando imagens noturnas de satélite e dados socioeconômicos disponíveis de regiões maiores. Três indicadores socioeconômicos foram selecionados para testar o método: Produto Interno Bruto (PIB), população e emprego. A relação entre esses três indicadores e a radiância quantificada nas imagens noturnas foi obtida por meio de análise de regressão simples aplicada nos 497 municípios do Estado do Rio Grande do Sul (RS). As equações do ajuste polinomial apresentaram o melhor Coeficiente de Determinação, sendo posteriormente submetidas à validação com dados de 50 municípios localizados no Estado de Santa Catarina. A validação mostrou um desempenho de estimação muito bom. As equações validadas foram usadas para estimar esses indicadores socioeconômicos para pequenas bacias hidrográficas localizadas no município de Caxias do Sul, RS, em três anos distintos: 2011, 2014 e 2018. Os resultados indicam que esta nova aplicação de imagens noturnas de satélite para estimar dados socioeconômicos pode ser uma ferramenta útil para a gestão do uso do solo e dos recursos hídricos de pequenas bacias hidrográficas.Palavras-chave: PIB, população, emprego, luz noturna, gestão dos recursos hídricos.

Temporal Variations in Chemical Proprieties of Waterbodies within Coastal Polders: Forecast Modeling for Optimizing Water Management Decisions

In polder-type land, water dynamics are heavily influenced by the artificial maintenance of water levels. Polders are low-lying areas of land that have been reclaimed from the sea or from freshwater bodies and are protected from flooding by dikes or other types of flood-protection structures. The water regime in polders is typically managed using a system of canals, pumps, and sluices to control the flow of water in and out of the area. In this study, the temporal changes in water salinity in the polder-type agricultural floodplain within the Neretva River Delta (NRD), Croatia, were analyzed by applying multivariate statistics and forecast modelling. The main aim of the study was to test the model that can be used in practice to forecast, primarily, water suitability for irrigation in a coastal low-lying agricultural catchment. The specific aim of this study was to use hydrochemistry data series to explain processes in water salinity dynamics and to test the model which may provide accurate salinity prediction, or finally select the conditions in which the model can be applied. We considered the accuracy of the model, and it was validated using independent data sets. To describe different patterns of chemical changes in different water classes due to their complex hydrological connectivity, multivariate statistics (PCA) were coupled with time-series analysis and Vector Autoregression (VAR) model forecasting. The multivariate statistics applied here did not indicate a clear connection between water salinity of the surface-water bodies and groundwater. The lack of correlation lies in the complex hydrological dynamics and interconnectivity of the water bodies highly affected by the artificial maintenance of the groundwater level within the polder area, as well as interventions in the temporal release of freshwater into the drainage canal network. Not all individual water classes contributed equally to the dominant patterns of ionic species identified by PCA. Apparently, land use and agricultural management practices in the different polders lead to uneven water chemistry and the predominant contributions of specific ions, especially nutrients. After applying the Granger causality test to reveal the causal information and explain hidden relationships among the variables, only two surface-water and two groundwater monitoring locations displayed a strong causal relationship between water electrical conductivity (ECw) as an effect and sea level as a possible cause. The developed models can be used to evaluate and emphasize the unique characteristics and phenomena of low-lying land and to communicate their importance and influence to management authorities and agricultural producers in managing and planning irrigation management in the wider Mediterranean area.

'I think this is where this lovely word "sustainability" comes in': Fruit and vegetable growers' narratives concerning the regulation of environmental water use for food production.

This article concerns UK commercial fruit and vegetable growers' narratives regarding the sustainability of water use for food production. In it we explore their perspectives on efforts by regulators to limit agricultural withdrawals of water from the natural environment in line with EU Water Framework Directive objectives, alongside their views on retailer sustainability commitments. Discourse analysis is used to investigate how the growers contested restrictive regulation, constructed their identities, portrayed other supply chain stakeholders, and conveyed their social relations with them. Using ErvingGoffman's theory of frontstage and backstage performances, the implications for the growers' water management decisions and their internalisation of sustainability agendas for water are examined. Whilst the growers gave accounts of purposely misrepresenting their water withdrawal practices and their discourse illustrated significant polarisation between environmental and agricultural interests, their underlying commitment to environmental sustainability was ambivalent, with both anti and pro-environmental attitudes expressed. The growers also frequently gave critiques of superficial sustainability in fresh produce supply chains. We argue that, given contemporary shifting definitions of agricultural identities, settings in which their construction is negotiated can provide windows of opportunity for conventional growers to engage in genuine pro-environmental performances that may deepen their assimilation of environmental goals and commitment to sustainable water use.

An Interdisciplinary Water Risk Assessment Framework for Sustainable Water Management in Ontario, Canada

AbstractThe Province of Ontario in Canada illustrates contemporary water security issues, where despite perception of water abundance, water challenges arise locally. Water risks stem from biophysical dimensions of groundwater depletion, low surface water flows, and degraded quality, and, contextual dimensions of regulatory uncertainty, public concerns and perception. While academic, policy, and practitioner interest is growing, literature reveals major gaps in comprehensive assessment of multidimensional water risks at the subwatershed scale. Addressing these gaps, the study developed a locally attuned and interdisciplinary water risk assessment framework. Using secondary mixed data analysis, the study integrated quantitative and qualitative data for water quantity and quality risks, regulatory trends, water user conflicts for 38 subwatersheds in Ontario. The framework identifies subwatersheds and sectors at high, moderate, and low risk along with media and public concern themes. The study finds high and moderate risk potential in at least 50% of studied subwatersheds for all water risk indicators and challenges the myth of water abundance in Great Lakes watershed of Ontario. The study advances knowledge in water risk assessment by applying social‐ecological perspectives, interdisciplinary approaches of Risk Theory, and mixed methods to provide a comprehensive evaluation of water security and demonstrates integration of social science perspectives in the field of sociohydrology. Our framework assesses interdisciplinary water risks to inform multisector sustainable water management decisions. While spatially scoped to populous subwatersheds of Ontario, this framework can be methodologically generalized to other geographical regions by using local data.

Modeling wildfire effects on streamflow in the Cascade Mountains, Oregon, USA

Increasing occurrence of large and severe wildfires represents a growing threat to forested watersheds and the many ecosystem services they provide. Past research has shown that wildfires can cause substantial increases in peak flows and annual water yields, leading to potential water quality concerns and land and water management challenges. However, responses have been variable, and there have been few studies at large basin scales, leading to uncertainties about post-fire hydrologic responses. To address these uncertainties, we projected the effect of three large wildfires (>70,000 ha) on streamflow in two important forested watersheds in the Cascade Range of Oregon, US. We modeled the streamflow response using the Soil and Water Assessment Tool (SWAT) model, calibrated on data from prior to the wildfires. We modified model parameters to represent the impacts of the wildfires based on burn severity maps. Burned and unburned scenarios were compared using random forest models to identify drivers of increased annual water yields and peak flows. Post-fire annual water yield changes were controlled by burn severity, annual precipitation, area burned, aridity, and vegetation type, while post-fire peak flow changes were controlled by burn severity, area burned, aridity, soil type, and geologic province. We also found that post-fire increases in annual water yields, peak flows, and low flows were greatest at the headwater scale but were more muted at the downstream basin scale. Our work provides valuable insights into the range of potential post-fire streamflow changes at the headwater and larger basin scale, which is becoming increasingly critical for effective forest and water management decisions.

Modelling prolonged stratification and hypoxia in dryland river waterholes during drought conditions

ABSTRACT Dryland river waterholes provide critical habitat and serve as refugia for aquatic animals during droughts, but the quality of these waterholes can often be severely compromised by hypoxic conditions that can lead to mass fish kills and loss of biodiversity. To assist river management, we developed a waterhole-scale ecohydrology model representing thermal stratification and dissolved oxygen regimes during prolonged drought periods in northern Murray-Darling Basin dryland rivers in Queensland, Australia. Model development focused around 6 typical waterholes in these rivers that were shallow (<5 m deep), highly turbid, and stratified with low dissolved oxygen. The model simulations utilised regional climate corrected for local factors such as diurnal vegetation shading and wind sheltering and successfully reproduced the prolonged stratification and hypoxia measured during drought conditions. The simulations highlight the distinct local climate each waterhole experiences due to the combined effects of river morphology and canopy cover that provide various degrees of solar shading and wind sheltering. The model can serve as a tool to inform water management decisions and climate adaptation strategies. Example scenarios demonstrate that (1) even where the canopy shading effect was small (5% at one site), further loss of riparian vegetation could increase temperature by 2–4 °C in warmer months with prolonged stratification; and (2) under an example RCP 8.5 climate change scenario, water temperature is likely to increase 2–10 °C, and oxygen saturation will decrease by 10% to 20% in the middle layers for most of the no-flow period by 2080–2099.

Remote Sensing and Aerodynamic Temperature-Based Energy Balance Models to Estimate Crop Evapotranspiration Rates

Different methods exist to measure or estimate actual crop evapotranspiration (ETa). However, some methods require a large number of data input or strict field conditions. Remote sensing based ETa algorithms based on extreme thermal pixels (hot and cold) have limitations when required extreme pixels are not present in the acquired thermal infra-red imagery. In addition, satellite overpass frequency and spatial pixel resolution may be a limitation for some agricultural fields and micro-climates. Surface energy balance methods that use surface radiometric temperatures often fail to perform well under drought, limited irrigation, salt affected soils, or under sparse vegetation conditions. One option is to measure or estimate the crop/surface sensible heat flux through the aerodynamic temperature approach, then calculate the available energy and solve the energy balance for latent heat flux. Thus, this study presents different published algorithms that characterize the crop or field surface aerodynamic temperature and then applies them to different conditions for evaluation. Determining spatial ETa continuously has the potential to improve the irrigation water management decision making. The aerodynamic temperature approach was initially developed with good results as a function of surface radiometric temperature, air temperature, crop leaf area index, and wind speed or surface aerodynamic resistance. However, the inclusion of the crop fractional percent cover and of a new resistance term (turbulent-mixing row resistance) greatly improved the estimation of the sensible heat and latent heat fluxes, when evaluated with heat flux data derived from eddy covariance energy balance towers. Results also indicate that the aerodynamic method has transferability potential to different regions, crops, and irrigation methods than the conditions encountered in the method development.

Historical Drought Events in the Early Years of Qing Dynasty in Shanxi Based on Hydrological Reconstructions

Droughts are serious natural disasters that adversely affect water resources, agriculture, the economy, and the environment. Reconstructing historical drought records is necessary to assess the impact of droughts and their evolution and has become a top priority to support and improve sustainable water management decisions. In this study, we used Shanxi Province as the research area, and meteorological data from the early years of Guangxu in the Qing Dynasty were reconstructed using historical rain and snow records. The Variable Infiltration Capacity (VIC) model is driven by the reconstruction of historical meteorological data. The study area’s monthly runoff and soil water sequence from 1875 to 1879 were simulated, and the hydrology and soil of the ancient historical period were reproduced in the absence of data. The results show the following: (1) The idea of reconstructing hydrological parameters using historical data is feasible and the VIC model can be used to study drought characteristics under specific scenarios. (2) The proportions of areas with runoff depths less than 10 mm throughout Shanxi from 1875 to 1879 were 55%, 48%, 58%, 19%, and 30%. The annual runoff depth in each region from 1875 to 1877 was less than 60 mm. The hydrological drought from 1875 to 1877 was very serious, and the area covered by the drought was relatively large. (3) The annual average soil water content of various regions was stable between 150 and 510 mm from 1875 to 1879. The soil water content had no apparent interannual variation. The area with soil water content less than 180 mm accounted for ratios as high as 31%. This research provides new ideas for ancient drought research and a scientific basis for regional drought prevention, mitigation, and water resources management, and ensures the orderly progress of agricultural production activities.

The intensification of short-duration rainfall extremes due to climate change – Need for a frequent update of intensity–duration–frequency curves

Numerous studies have investigated future changes in extreme precipitation by employing climate models. However, trends in extreme short-duration (20–180 min) rainfall intensities, that is, design storm rainfall intensities used for stormwater infrastructure design, have received considerably less attention despite their importance. This study quantified the effect of climate change on design storm intensity based on observations. Trends were investigated for diverse short-term rainfall durations, ranging from 20 to 180 min, at 11 meteorological stations in Northern Europe, Estonia. The Mann-Kendall test and Sen’s slope estimator were used to detect trends and calculate the trend magnitudes by analyzing a 70 year period of high-resolution temporal observed rainfall data. The Sen’s slope indicated a positive magnitude of slopes for all the durations and stations investigated, and two stations in Northeast Estonia showed significantly increasing trends (p < 0.05). Unsurprisingly, the spatial distribution of trends revealed notable variations from station to station, as extreme rainfall events are heavily localized due to cloudburst. Despite this variety, it can be generalized that the annual maximum rainfall intensities in Estonia have increased at an average rate of 4 % per decade due to changing climate conditions, invariant of the rainfall duration analyzed. The use of decades enables to easily keep the intensity–duration–frequency curves updated, and it is more practical and relatable for engineers as well. The findings of this study provide critical knowledge for urban water management decision-makers, indicating the need to frequently update urban design criteria to design climate resilient urban infrastructure.

Water demands of permitted and unpermitted cannabis cultivation in Northern California

Illicit water use for irrigated agriculture can have substantial impacts on the environment and complicates water management decision-making. Water demand for illicit cannabis farming in California has long been considered a threat to watershed health, yet an accounting of cannabis irrigation has remained elusive, thereby impeding effective water policy for the state’s nascent legal cannabis industry. Using data obtained from both permitted and unpermitted cultivation operations, the current study applies novel water-use models to cannabis farms in Northern California to estimate their cumulative and relative water footprints. Our results indicated substantial variation in total water extraction volumes for cannabis farming between watersheds and that most cannabis water use was concentrated in a subset of watersheds, rather than evenly spread across the landscape. Water extraction volumes for unpermitted cannabis were consistently greater than permitted cannabis in the dry season, when streams are most vulnerable to impacts from water diversions. Results from scenario modeling exercises indicated that if all existing unpermitted farms were to become permitted and comply with regulations that prohibit surface water diversions in the dry season, nearly one third (34 of 115) of the study watersheds would experience a 50% reduction in dry season water extraction. In comparison, modest expansion of off-stream storage by all cannabis farms could reduce dry season extraction by 50% or greater in more than three quarters (96 of 115) of study watersheds. Combining diversion limits with enhanced storage could achieve dry season extraction reductions of 50% or greater in 100 of 115 watersheds. Our findings suggest that efforts to address the environmental impacts of unpermitted cultivation should focus on watersheds with greatest water demands and that programs that support expansion of off-stream storage can be helpful for reducing pressures on the environment and facilitating the transition of unpermitted farms to the regulated market.