Enhancing speed and scalability of the ParFlow simulation code

Regional hydrology studies are often supported by high resolution simulations of subsurface flow that require expensive and extensive computations. Efficient usage of the latest high performance parallel computing systems becomes a necessity. The simulation software ParFlow has been demonstrated to meet this requirement and shown to have excellent solver scalability for up to 16,384 processes. In the present work we show that the code requires further enhancements in order to fully take advantage of current petascale machines. We identify ParFlow's way of parallelization of the computational mesh as a central bottleneck. We propose to reorganize this subsystem using fast mesh partition algorithms provided by the parallel adaptive mesh refinement library p4est. We realize this in a minimally invasive manner by modifying selected parts of the code to reinterpret the existing mesh data structures. We evaluate the scaling performance of the modified version of ParFlow, demonstrating good weak and strong scaling up to 458k cores of the Juqueen supercomputer, and test an example application at large scale.Comment: The final publication is available at link.springer.co

Reply to comment by H. Lough, Department of Civil Engineering, University of Canterbury, Christchurch, New Zealand, on the paper “Stream depletion predictions using pumping test data from a heterogeneous stream–aquifer system (a case study from the Great Plains, USA)”

1. General remark 2. The study by Kollet and Zlotnik (2003) 3. Remark on the explanation of the drawdown behavior 4. Remark on the re-analysis of the data from piezometer C2d 5. Summar

Response of Convective Boundary Layer and Shallow Cumulus to Soil Moisture Heterogeneity: A Large‐Eddy Simulation Study

In this study, the impact of varying soil moisture heterogeneity (spatial variance and structure) on the development of the convective boundary layer and shallow cumulus clouds was investigated. Applying soil moisture heterogeneity generated via spatially correlated Gaussian random fields based on a power law model and idealized atmospheric vertical profiles as initial conditions, three sets of large‐eddy simulations provide insight in the influence of soil moisture heterogeneity on the ensuing growth of the convective boundary layer and development of shallow cumulus clouds. A sensitivity on the strong, weak, and unstructured soil moisture heterogeneity is investigated. The simulation results show that domain‐averaged land surface sensible heat and latent heat flux change strongly with changing soil moisture variance because of the interactions between surface heterogeneity and induced circulations, while domain means of soil moisture are identical. Vertical profiles of boundary layer characteristics are strongly influenced by the surface energy partitioning and induced circulations, especially the profiles of liquid water and liquid water flux. The amount of liquid water and liquid water flux increases with increasing structure. In addition, the liquid water path is higher in case of strongly‐structured heterogeneity because more available energy is partitioned into latent heat and more intensive updrafts exist. Interestingly, the increase of liquid water path with increasing soil moisture variance only occurs in the strongly structured cases, which suggests that soil moisture variance and structure work conjunctively in the surface energy partitioning and the cloud formation

Processos de comunicação e educação ambiental na formação de multiplicadores em resíduos sólidos no CIPAE G8 do Vale do Taquari-RS

O G8 é um consórcio de pequenos municípios do Rio Grande do Sul que atua coletivamente para o enfrentamento de questões da gestão pública e através do Programa Intermunicipal de Gestão Integrada de Resíduos – PIGIRS atende às exigências previstas, para o âmbito municipal, na Política Nacional de Resíduos Sólidos, a qual prevê e aponta para a responsabilidade compartilhada pelo ciclo de vida dos produtos e gestão integrada dos resíduos. Com a necessidade de ações que contribuam para a construção de sociedades sustentáveis e com a cobrança do Ministério Público para o cumprimento do PIGIRS (2013) pelo G8, no que se refere à educação ambiental, se dá início a um processo de formação, o qual segue as prerrogativas propostas pelo Ministério do Meio Ambiente quando cria a metodologia dos Coletivos Educadores. Os coletivos são constituídos por instituições e grupos que passam por processos formativos permanentes, participativos, continuados e voltados à diversidade de habitantes de um território, caso do G8. O Coletivo Educador está articulado ao que está posto no Programa Nacional de Educação Ambiental (ProNEA). Para tanto, problematiza-se a metodologia de formação, a apropriação do conhecimento pelos participantes e os modos de multiplicação em cada um dos municípios onde ocorreram formações. O objetivo do estudo é investigar processos de intervenção para a formação de multiplicadores em comunicação e educação ambiental em ambiente não-formal, voltados para a área de resíduos sólidos domésticos no âmbito do G8. O estudo atrela-se a um dos Objetivos de Desenvolvimento Sustentável, ODS 11: Tornar as cidades e os assentamentos humanos inclusivos, seguros, resilientes e sustentáveis, especificamente à meta de, até 2030, reduzir o impacto ambiental negativo per capita das cidades, inclusive prestando especial atenção à qualidade do ar, gestão de resíduos municipais e outros. A metodologia caracteriza-se como qualitativa, estudo de caso e, quanto aos fins a pesquisa é exploratória, descritiva e aplicada, baseada no estudo bibliográfico, documental e de campo, essa de caráter intervencionista. O tratamento de dados apoia-se na análise textual. Como resultados apresenta-se a análise das categorias de apropriações metodológicas e apropriações da formação nas quais é possível evidenciar que a formação de multiplicadores por meio de práticas colaborativas é potente, gera possibilidades de apropriação diversas pelos multiplicadores, o que se pode visualizar nas intervenções viabilizadas pela formação, além disso verificou-se suas possibilidades de potencializar a criação de Coletivos de Educação Ambiental. No entanto, esta possibilidade diferencia-se em cada município, já que em alguns a motivação foi maior que em outros, ademais a situação de pandemia dificultou a continuidade das ações, desfavorecendo a criação efetiva dos Coletivos Educadores. Mas evidenciou-se que o processo de formação de multiplicadores em resíduos sólidos do CIPAE G8 resultou na capacitação dos multiplicadores em educação ambiental e esses realizaram práticas de intervenção, as quais passaram a constituir parte de sua experiência de vida. Depois da formação estão mais próximos da formação de Coletivos Educadores que antes, considerando-se que, ao menos temporariamente e com o apoio dos pesquisadores, organizaram-se como tal.The G8 is a consortium of small municipalities in Rio Grande do Sul that works collectively to face public management issues and through the Intermunicipal Program for Integrated Waste Management - PIGIRS meets the requirements foreseen, for the municipal scope, in the National Policy for Solid Waste, which provides for and points to shared responsibility for the life cycle of products and integrated waste management. With the need for actions that contribute to the construction of sustainable societies and the collection of the Public Ministry for the fulfillment of PIGIRS (2013) by the G8, with regard to environmental education, a training process begins, which it follows the prerogatives proposed by the Ministry of the Environment when it creates the methodology of Collective Educators. The collectives are made up of institutions and groups that undergo permanent, participatory, continuous training processes and focused on the diversity of inhabitants of a territory, as in the case of the G8. The Educative Collective is linked to what is included in the National Environmental Education Program (ProNEA). To this end, the training methodology, the appropriation of knowledge by the participants and the multiplication modes that in each of the municipalities where training took place are problematized. The objective of the study is to investigate intervention processes for the formation of multipliers in communication and environmental education in a non-formal environment, focused on the area of domestic solid waste within the scope of the G8. The study is linked to one of the Sustainable Development Goals, SDG 11: Making cities and human settlements inclusive, safe, resilient and sustainable, specifically to the goal of, by 2030, reducing the negative environmental impact per capita of cities, including paying special attention to air quality, municipal waste management and others. The methodology is characterized as qualitative, case study and, as for the purposes, the research is exploratory, descriptive and applied, based on bibliographic, documentary and field study, this is of an interventionist character. Data processing is supported by textual analysis

Forage yield and chemical composition of pearl millet varieties (Pennisetum glaucum (L.) R. BR.)

O experimento foi realizado para avaliar a produtividade, o perfilhamento, a porcentagem de lâmina/haste e a composição bromatológica (PB, FDN e FDA) de três variedades (Africano, Americano e BN-2) de milheto (Pennisetum glaucum (L) R. Br.) em três idades de corte (35, 42 e 49 dias). Na primeira fase da pesquisa, foi utilizado delineamento experimental em blocos casualizados, em um esquema de parcelas subdivididas no tempo, com quatro repetições. Na fase de rebrota, o delineamento foi inteiramente casualizado, com o mesmo número de repetições. As parcelas principais foram representadas pelas variedades e as subparcelas, pelas três idades de corte. A produção média de MS durante a fase de corte foi similar entre as variedades (4.360, 4.204 e 3.247 kg/MS/ha para as variedades Africano, Americano e BN-2, respectivamente), ao passo que os teores de PB, FDN e FDA e a relação lâmina/haste diferiram (Americano: 16,71% PB; 56,29% FDN e 30,04% FDA; BN-2: 16,30% PB; 55,93% FDN e 30,98% FDA; Africano: 15,36% PB; 60,55% FDN e 34,55% FDA). Com o avançar da idade de corte, a produtividade e os teores de FDN e FDA aumentaram, enquanto a relação lâmina/haste e o teor de PB decresceram linearmente. Na rebrota, a produtividade diminuiu, mas os teores médios de PB, FDN e FDA não diferiram entre as variedades (Americano: 20,21% PB; 53,19% FDN e 26,72% FDA; BN-2: 20,43% PB; 53,42% FDN e 27,06% FDA; Africano: 19,75% PB; 52,45% FDN e 27,44% FDA), observando-se diferença para a relação média lâmina/haste. O valor nutritivo da forragem na rebrota manteve-se acima dos encontrados na primeira fase de corte. As maiores porcentagens de lâminas foram observadas nas variedades Americano e BN-2 e as maiores de hastes, na variedade AFRICANO. As melhores variedades para uso na alimentação animal são: Americano e BN-2 e a melhor idade de corte é de 49 dias. __________________________________________________________________________________ ABSTRACTThe objective of this experiment was to evaluate the productivity, tillering, leaf blade/stem ratio and chemical composition (CP, NDF and ADF) of three pearl millet (Pennisetum glaucum (L.) R. BR.) varieties (African, American and BN-2) submitted to three different cutting ages (35, 42 and 49 days). During the first growth period, a split-plot arrangement in a complete randomized block design was used with varieties being the main plots and cutting ages the subplots. During regrowth, a complete randomized design was used. In both cases, there were four replications per treatment. Dry matter yield among varieties was similar (4,360, 4,204, and 3,247 kg/DM/ha) for the varieties African, American and BN-2, respectively. The CP (15.36, 16.71, and 16.3%), NDF (60.55, 56.29, and 55.93%) and ADF (34.55, 30.04, and 30.98%) concentrations as well as the leaf blade/stem percentages differed among African, American and BN-2 varieties, respectively. Dry matter productivity, NDF, and ADF concentrations increased with the advance of cutting age while leaf blade/stem ratio and CP decreased linearly. Productivity was reduced during regrowth, however, the average CP (19.75, 20.21, and 20.43%), NDF (52.45, 53.19, and 53.42%) and ADF (27.44, 26.72, and 27.06%) concentrations did not differ among African, American and BN-2 varieties during this period, respectively. The leaf blade/stem ratio, however, differed among them during regrowth. Forage nutritive value at regrowth was greater than during first growth period. American and BN-2 varieties presented the highest leaf blade percentage while the African variety showed the highest stem percentage. Thus, the best forage varieties are American and BN-2 and the best cutting age is 49 days

Causal deep learning models for studying the Earth system

Earth is a complex non-linear dynamical system. Despite decades of research and considerable scientific and methodological progress, many processes and relations between Earth system variables remain poorly understood. Current approaches for studying relations in the Earth system rely either on numerical simulations or statistical approaches. However, there are several inherent limitations to existing approaches, including high computational costs, uncertainties in numerical models, strong assumptions about linearity or locality, and the fallacy of correlation and causality. Here, we propose a novel methodology combining deep learning (DL) and principles of causality research in an attempt to overcome these limitations. On the one hand, we employ the recent idea of training and analyzing DL models to gain new scientific insights into relations between input and target variables. On the other hand, we use the fact that a statistical model learns the causal effect of an input variable on a target variable if suitable additional input variables are included. As an illustrative example, we apply the methodology to study soil-moisture–precipitation coupling in ERA5 climate reanalysis data across Europe. We demonstrate that, harnessing the great power and flexibility of DL models, the proposed methodology may yield new scientific insights into complex non-linear and non-local coupling mechanisms in the Earth system.</p

Towards the representation of groundwater in the Joint UK Land Environment Simulator

Groundwater is an important component of the hydrological cycle with significant interactions with soil hydrological processes. Recent studies have demonstrated that incorporating groundwater hydrology in land surface models (LSMs) considerably improves the prediction of the partitioning of water components (e.g., runoff and evapotranspiration) at the land surface. However, the Joint UK Land Environment Simulator (JULES), an LSM developed in the United Kingdom, does not yet have an explicit representation of groundwater. We propose an implementation of a simplified groundwater flow boundary parameterization (JULES‐GFB), which replaces the original free drainage assumption in the default model (JULES‐FD). We tested the two approaches under a controlled environment for various soil types using two synthetic experiments: (1) single‐column and (2) tilted‐V catchment, using a three‐dimensional (3‐D) hydrological model (ParFlow) as a benchmark for JULES’ performance. In addition, we applied our new JULES‐GFB model to a regional domain in the UK, where groundwater is the key element for runoff generation. In the single‐column infiltration experiment, JULES‐GFB showed improved soil moisture dynamics in comparison with JULES‐FD, for almost all soil types (except coarse soils) under a variety of initial water table depths. In the tilted‐V catchment experiment, JULES‐GFB successfully represented the dynamics and the magnitude of saturated and unsaturated storage against the benchmark. The lateral water flow produced by JULES‐GFB was about 50% of what was produced by the benchmark, while JULES‐FD completely ignores this process. In the regional domain application, the Kling‐Gupta efficiency (KGE) for the total runoff simulation showed an average improvement from 0.25 for JULES‐FD to 0.75 for JULES‐GFB. The mean bias of actual evapotranspiration relative to the Global Land Evaporation Amsterdam Model (GLEAM) product was improved from −0.22 to −0.01 mm day−1. Our new JULES‐GFB implementation provides an opportunity to better understand the interactions between the subsurface and land surface processes that are dominated by groundwater hydrology

Implementation and scaling of the fully coupled Terrestrial Systems Modeling Platform (TerrSysMP) in a massively parallel supercomputing environment – a case study on JUQUEEN (IBM Blue Gene/Q)

Continental-scale hyper-resolution simulations constitute a grand challenge in characterizing non-linear feedbacks of states and fluxes of the coupled water, energy, and biogeochemical cycles of terrestrial systems. Tackling this challenge requires advanced coupling and supercomputing technologies for earth system models that are discussed in this study, utilizing the example of the implementation of the newly developed Terrestrial Systems Modeling Platform (TerrSysMP) on JUQUEEN (IBM Blue Gene/Q) of the Jülich Supercomputing Centre, Germany. The applied coupling strategies rely on the Multiple Program Multiple Data (MPMD) paradigm and require memory and load balancing considerations in the exchange of the coupling fields between different component models and allocation of computational resources, respectively. These considerations can be reached with advanced profiling and tracing tools leading to the efficient use of massively parallel computing environments, which is then mainly determined by the parallel performance of individual component models. However, the problem of model I/O and initialization in the peta-scale range requires major attention, because this constitutes a true big data challenge in the perspective of future exa-scale capabilities, which is unsolved

How uncertain are precipitation and peak flow estimates for the July 2021 flooding event?

The disastrous July 2021 flooding event made us question the ability of current hydrometeorological tools in providing timely and reliable flood forecasts for unprecedented events. This is an urgent concern since extreme events are increasing due to global warming, and existing methods are usually limited to more frequently observed events with the usual flood generation processes. For the July 2021 event, we simulated the hourly streamflows of seven catchments located in western Germany by combining seven partly polarimetric, radar-based quantitative precipitation estimates (QPEs) with two hydrological models: a conceptual lumped model (GR4H) and a physically based, 3D distributed model (ParFlowCLM). GR4H parameters were calibrated with an emphasis on high flows using historical discharge observations, whereas ParFlowCLM parameters were estimated based on landscape and soil properties. The key results are as follows. (1) With no correction of the vertical profiles of radar variables, radar-based QPE products underestimated the total precipitation depth relative to rain gauges due to intense collision–coalescence processes near the surface, i.e., below the height levels monitored by the radars. (2) Correcting the vertical profiles of radar variables led to substantial improvements. (3) The probability of exceeding the highest measured peak flow before July 2021 was highly impacted by the QPE product, and this impact depended on the catchment for both models. (4) The estimation of model parameters had a larger impact than the choice of QPE product, but simulated peak flows of ParFlowCLM agreed with those of GR4H for five of the seven catchments. This study highlights the need for the correction of vertical profiles of reflectivity and other polarimetric variables near the surface to improve radar-based QPEs for extreme flooding events. It also underlines the large uncertainty in peak flow estimates due to model parameter estimation.</p