Humid Tropical Climate Research Articles

Enhancing Airflow in Row Houses: The Impact of Stilt Floors on Ventilation Efficiency in Humid Tropical Climates

Enhancing Airflow in Row Houses: The Impact of Stilt Floors on Ventilation Efficiency in Humid Tropical Climates

PMVd/PPDd model for predicting thermal comfort in air-conditioned buildings in hot and humid regions of Sub-Saharan Africa

The model for predicting thermal comfort conditions established by Fanger remains widely used in scientific work, as a default means of in situ measurements. However, the use of Fanger data leads to dissatisfaction among users of air-conditioned buildings in humid tropical areas. This conclusion emerges from the work of Kemajou and al. (Cameroon) and Olissan and al. (Benin) in 2012, after survey studies on the judgments of thermal sensations of people occupying various air-conditioned spaces. This article develops a correction model for the Fanger model, by coupling the latter to models for predicting skin temperature and heat loss by evaporation of sweat through the skin, as well as to the skin thermal sensitivity of people active in a humid tropical climate. The model thus determined shows that the predicted optimal comfort temperatures are located in the range of 26.1 °C to 27.5 °C and better meets the expectations of the populations in this region. The respective differences with the investigations of Kemajou and al. and those of Olissan and al. are 0.40 °C and 0.55 °C. It also appears that the comfort humidity range is 30% to 80%, apart from any other safety measures.

Follicular persistence, oestradiol level and conception on the first and second day of oestrus and influence of thermal stress in cross-bred dairy cows manifesting prolonged oestrus

Increasing incidence of prolonged oestrus reported in cross-bred dairy cows bred through artificial insemination (AI), is attributed to various causative factors and underlying mechanisms. The present study was to assess the pattern of follicular growth, oestrogen secretion, and conception on the first and second day of oestrus and to understand the influence of thermal stress as a causative factor for oestrus prolongation. The year-round study involved 52 crossbred cows intensively managed under a hot humid climate, during their second and third months postpartum. Animals were examined for the status of ovarian follicles, oestrogen level, and conception to AI on Day 0 and Day 1 of oestrus confirmation and the findings were compared across seasons. While oestrus detection rate (ODR) and conception of AI were lowest during the summer season attributable to maximum TS, better ODR (P<0.05) and more prolonged oestrus (P<0.01) occurred during the seasons of favourable climate having least TS and better green fodder availability. Besides, the occurrence of larger follicles and almost similar oestradiol levels on Day 0 and Day 1 of oestrus, better conception rate for double AI (63.16 %) than total AI (48.48 %) indicated prolonged oestrus and involvement of delayed ovulation among the causation. Comparison of the seasonal pattern of follicular growth, oestrogen level, and conception to AI between Day 0 and Day 1 further clarifies the influence of TS and increased milk production as the potential contributors to the occurrence of prolonged oestrus in cross-bred cows under the hot humid tropical climate. Keywords: Crossbred cow, Oestrogen, Prolonged oestrus, Thermal stress

Mineralogical and geochemical studies of shales from Kopili Formation, Dima Hasao district Assam, North East India: Insights into diagenesis, deposition and provenance

The Eocene Kopili Formation in the Assam foreland basin records sediment sources, tectonic activity and depositional environments following the India-Eurasia collision. Mineralogical and geochemical analysis of these shales exposed near Garampani, Assam, NE India was conducted to study the diagenesis, palaeoweathering, palaeosalinity, redox conditions, tectonic settings and provenance. The Kopili Formation is composed of mainly shale with thin beds of limestone, black shale and sandstone and these units overlie the Upper Sylhet Limestone. The presence of goethite-rich phosphatic nodules, secondary precipitation within the fissile planes of shale and the occurrence of anatase, talc, smectite and chlorite suggest diagenesis. The prevalence of kaolinite and mean Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), Al2O3/MgO and Rb/Sr values of 86.73, 97.26, 16.36 and 1.32, respectively indicates extensive source rock weathering in humid tropical climate. The Index of Compositional Variation (ICV) values ranging between 0.47 and 2.38 also signify high weathering and tectonically active basin. The Sr/Ba ratio 0.34 ± 0.27 (mean±2σ) suggest overall freshwater basin. The Ni/Co (2.84 ± 2.29), V/Cr (1.65 ± 0.45) and Ce/Ce∗ (0.97 ± 0.63) suggest fluctuating redox environment. The samples predominantly cluster in continental island arc domain on the Th-Sc-Zr/10, La-Th-Sc and Th-Co-Zr/10 discriminant diagrams. Elemental ratios of Th/Sc, La/Sc, Cr/Th with average 0.91, 3.18, 10.13 respectively and La/Th-Hf plot suggest a felsic source rock. The Kopili shale was deposited in freshwater, continental island arc basin with fluctuating redox conditions, receiving sediments from weathered Himalayan granites and gneisses under a warm and humid climate. Subsequently, they underwent diagenetic alteration by low-pH fluid(s).

Agri-Solar Water Pumping design, energy, and environmental analysis: A comprehensive study in Tropical Humid climate

Agrivoltaics is an innovative approach where solar energy, water, land and biodiversity are integrated into the same area to maximize resource utilization for sustainable development, also known as Agrivoltaism. The combination of solar water pumping and agri-solar has led to the development of a new generation of irrigation systems that are highly sustainable and efficient. Agri-solar water pumping can irrigate crops, feed livestock, clean solar modules, cool the PV system, generate energy, store water, and provide community drinking water. This paper addresses the basic design and capacity requirements of solar water pumping systems for irrigating a 0.5-hectare Agrivoltaics system in Kuala Lumpur. The SISIFO tool has been used to simulate the Agri-solar water pumping performance for tropical humid climatic conditions. The various parameters like site details, climate data, type of PV modules, DC pump -motor and converters are used as input data to evaluate the energy yield parameters (output energy in DC and AC form), hydraulic parameters (volume of water pumped), loss parameters (capture and system losses) and efficiency parameters (performance of the system). Lettuce was chosen as it is fast growing with good yield per hectare. Based on the result, a detailed analysis of the agrivoltaic lettuce plant is performed. A detailed analysis of the solar resource assessment, system design, Key performance indicators, loss analysis and environmental analysis of the Agri-solar water pumping has been carried out. Considering their specific climatic conditions, this can significantly assist policymakers in selecting the optimal solar pumping station for agrivoltaic plants. The importance of considering various factors when choosing a solar pumping station for agrivoltaics is also highlighted

Transcriptome analysis and genome-wide identification of the dehydration-responsive element binding gene family in jackfruit under cold stress

BackgroundJackfruit (Artocarpus heterophyllus Lam.) is the world’s largest and heaviest fruit and adapts to hot, humid tropical climates. Low-temperature injury in winter is a primary abiotic stress, which affects jackfruit growth and development. Therefore, breeding cold-resistant varieties and identifying the vital genes in the process of cold resistance are essential. The dehydration-responsive element binding (DREB) gene family is among the subfamily of the APETALA2/ethylene response factor transcription factor family and is significant in plant abiotic stress responses.MethodsIn this study, a comparative analysis of the cold resistance property of ‘GuangXi’ (‘GX’) and ‘Thailand’ (‘THA’) jackfruit strains with different cold resistance characteristics was performed through chlorophyll fluorescence and transcriptome sequencing.ResultsWe found that differentially expressed genes (DEGs) are significantly enriched in the metabolic processes. Here, 93 DREB genes were identified in the jackfruit genome, and phylogenetic analysis was used to classify them into seven groups. Gene structure, conserved motifs, chromosomal location, and homologous relationships were used to analyze the structural characteristics of the DREB family. Transcriptomics indicated that most of the AhDREB genes exhibited down-regulated expression in ‘THA.’ The DEGs AhDREB12, AhDREB21, AhDREB29, and AhDREB34 were selected for quantitative real-time PCR, and the results showed that these genes also had down-regulated expression in ‘THA.’ConclusionsThe above results suggest the significance of the DREB family in improving the cold resistance property of ‘GX.’

Role of Urban Trees in Enhancing the Thermal Comfort of Rapidly Urbanizing Cities: An Analysis of Tropical Asian Tree Species Based on Physiological Equivalent Temperature (PET)

AbstractBackgroundThermal comfort significantly influences well-being, productivity, and living conditions in outdoor environments, particularly in rapidly urbanizing, warm, humid tropical climates. This study assessed the influence of 5 five common urban tree species (Cassia fistula,Tectona grandis,Plumeria obtusa,Mangifera indica, andTerminalia catappa) on outdoor thermal comfort, using the physiological equivalent temperature (PET) index in Colombo, Sri Lanka, as a case study for a tropical humid city.MethodsField data collection encompassed measuring air and surface temperature, relative humidity, wind velocity, solar radiation, cloud cover, and sky view factor under tree canopies and adjacent exposed areas. The RayMan model was employed to estimate PET in both areas.ResultsOur findings indicated that PET was consistently higher in exposed areas compared to under the tree canopy, with an average difference of 5.61 °C. Among tree parameters, sky view factor (SVF) demonstrated the most significant correlation with thermal comfort, followed by crown diameter and tree height. Furthermore, notable variations in thermal comfort were observed among tree species, withTerminalia catappaoutperformingPlumeria obtusa, particularly on sunny days.ConclusionRegression analysis highlighted the importance of integrating trees with large crowns and low SVF to create thermally comfortable outdoor spaces. Consequently,Terminalia catappaemerged as the most suitable tree species for enhancing thermal comfort in Colombo’s outdoor urban areas out of the 5 selected species. These insights will aid in selecting appropriate tree species and parameters, fostering improved outdoor thermal comfort in tropical humid cities, and facilitating sustainable urban planning and design strategies.

An Evaluation of the Land Available for Sustainable Sugarcane Cultivation and Potential for Producing Ethanol and Bioelectricity in Angola

With a predominantly humid tropical climate and a large area for expanding agricultural activities, Angola has in principle favorable conditions for bioenergy production. The focus of this study was to evaluate the availability of suitable land for producing sugarcane. This crop is highly efficient in converting solar energy into biomass for energy purposes in Angola. To this end, this paper outlines a method for data collection, processing, and analysis divided into three sections. The first section uses the GAEZ (Global Agroecological Zones) database and QGIS (Quantum GIS) software (version 3.22.5) to assess land availability for sugarcane cultivation in Angola, classifying the regions’ suitability into four levels. The second section supplements this with data from the FAOSTAT database, systematically excluding areas with restrictions, such as protected zones, land already used for other crops, and regions unsuitable for sugarcane. Finally, the third section employs an agricultural yield model to estimate the potential yield of sugarcane based on climatic parameters and the amount of bioenergy (ethanol and bioelectricity) able to be produced in the available land. Under these criteria, this study identified the existence of 6.3 Mha in lands of good agricultural suitability, with water resources, corresponding to 5% of the Angolan territory, distributed in seven provinces of the country, especially in the provinces of Cuando Cubango and Cunene, where 85% of the very suitable land under irrigation is located. Adopting a model of agricultural productivity, assuming irrigation and adequate agricultural practices, such area could produce approximately 956 million tons of sugarcane annually, which is significantly higher than the current production in this country. This amount of feedstock processed using current technology could potentially produce 81.3 GL of ethanol and 176.9 TWh of electricity with low GHG emissions per year, which is able to mitigate, as a whole, circa 60.3 MtCO2-eq/year by displacing gasoline in light vehicles and diesel and natural gas consumed in power generation.

A Model for Determining the Thermal Comfort of Fishermen’s Houses on Coasts with Humid Tropical Climate

Fishermen’s houses on the coastal area of Dusun Karama Tengah, located at coordinates 119° 23’ 0” with 119° 23’ 9” BT, and 5° 13’ 28” LS with 5° 13’ 36” LS, with a humid tropical climate, has poor thermal comfort, and is not in the 22,8°C-27,1°C comfort category. Residents and house occupants feel stifled, hot, and uncomfortable during the day. Environmental factors, use of materials, construction, and the architecture of the fishing houses greatly contribute to the thermal comfort, apart from weather and climate factors. The aim of this research is to develop an innovative model for determining the thermal comfort of the fishermen’s homes. This research uses survey methods and observations of several factors that contribute to the thermal comfort during the day. It also uses expert system analysis techniques, certainty factors, based on Geographic Information System (GIS). A total of 107 fishermen’s housing units studied had poor thermal comfort, especially at 11:00-13:00 WITA or at 03:00-05.00 GMT. The poor thermal comfort of the fishermen’s houses is because they do not apply the principles of eco-building, green-architecture, and the lack of: facade, overhang, insulation, trees and parks, as well as the large use of low-density building projects in the form of zinc and triplex ceilings. This research has not taken into account the level of heat reduction of the house materials and the environment, so it is expected to be done in the upcoming research.

The Eastern Ghat of India: A review on plant ecological perspectives

The Eastern Ghats, a discontinuous range of mountains spanning Odisha, Andhra Pradesh, Telangana, Tamil Nadu, and Karnataka has a humid tropical monsoon climate with moderate to high temperatures and heavy rainfall. The Eastern Ghats offer a diverse range of flora and fauna, including endemics. The vegetation is classified into various forest types, including moist deciduous, dry deciduous, dry evergreen, evergreen, semi-evergreen, scrub jungles, and savannah. Eastern Ghat reflects the healthy carrying capacity of the ecosystem. The Eastern Ghats boasts a diverse plant community, with over 3200 flowering plant species, largely due to geographic factors, high seasonality, and elevational variations. The Eastern Ghats, a significant biodiversity granary in India, has been the subject of numerous taxonomic and quantitative surveys. The eastern coast of India's eastern forest (Eastern Ghats) is facing a decline in plant diversity due to overexploitation, habitat destruction, and rampant grazing. This has led to species loss and extinction. The forest cover has also decreased due to anthropogenic pressures. However, there is a lack of significant research on plant species population dynamics, soil surveys, soil chemistry, geomorphology, geobotany, pedology, edaphology, and phytochemistry. To address this, modern science and technology approaches, such as geomorphometry and geobotanical studies using Remote Sensing and GIS techniques, are the need of the hour.

How much rainwater contributes to a spring discharge in the Guarani Aquifer System: insights from stable isotopes and a mass balance model

ABSTRACT Outcrops play an important role in groundwater recharge. Understanding groundwater origins, dynamics and its correlation with different water sources is essential for effective water resources management and planning in terms of quantity and quality. In the case of the Guarani Aquifer System (GAS) outcrop areas are particularly vulnerable to groundwater pollution due to direct recharge processes. This study focuses on the Alto Jacaré-Pepira sub-basin, a watershed near Brotas, a city in the central region of the state of São Paulo, Brazil, where groundwater is vital for supporting tourism, agriculture, urban water supply, creeks, river and wetlands. The area has a humid tropical climate with periods of both intense rainfall and drought, and the rivers remain perennial throughout the year. Therefore, the aim of this study is to investigate the interconnections between a spring and its potential sources of contribution, namely rain and groundwater, in order to elucidate the relationships between the different water sources. To achieve this, on-site monitoring of groundwater depth, rainfall amount, and stable isotope ratios (deuterium (2H) and oxygen-18 (18O)) from rain, spring discharge, and a monitoring well was carried out from 2013 to 2021. The results indicate that the mean and standard deviations for δ18O in rainwater exhibit higher variability, resulting in −4.49 ± 3.18 ‰ VSMOW, while δ18O values from the well show minor variations, similar to those of the spring, recording −7.25 ± 0.32 ‰ and −6.94 ± 0.28 ‰ VSMOW, respectively. The mixing model’s outcomes reveal seasonal variations in water sources contribution and indicate that groundwater accounts for approximately 80 % of spring discharge throughout the year. Incorporating stable isotopes into hydrological monitoring provides valuable data for complementing watershed analysis. The values obtained support the significance of the aquifer as a primary source, thereby offering critical insights into stream dynamics of the region.

“Out-of-India” dispersal of the extinct fabaceous genus Podocarpium Braun ex Stizenberger

Podocarpium is a well-known extinct single-seeded legume genus having extensive Cenozoic fossil occurrences from East Asia to central Europe. To date, there have been no fossil records of this genus from South Asia, including India. Here, we report and describe for the first time a well-preserved fossil pod from the early Eocene of Rajasthan, western India, assigned to extinct Podocarpium based on detailed morphology. It is characterized by an asymmetrical, oblique valve with a single oblong seed, a distinctly curved stipe, a wingless margin, a prominent vascular strand along the dorsal suture that anastomoses into the apex, a weakly curved ventral suture, fine reticulate veins, a short acuminate apex, and a narrowly acute base. This discovery is the oldest fossil evidence of Podocarpium recorded to date worldwide. Together with previous fossil records, we suggest an “Out-of-India” dispersal hypothesis to explain the biogeography of this extinct legume genus. It might have originated under warm and humid tropical climate conditions in the early Eocene of India (South Asia), then migrated to China (East Asia), and subsequently spread north and westward to Europe.

A new foliicolous fossil-species of Asterina Lév. (Asterinaceae; Asterinales) associated with Calophyllum L. from the Siwalik of Eastern Himalaya and its implications

The present study reports and describes a new foliicolous fossil-species of Asterina Lév. (Asterinaceae: Asterinales: Dothideomycetes) namely, A. siwalika sp. nov., on a compressed leaf assigned to modern Calophyllum L. (Calophyllaceae) recovered from the Siwalik sediments (early Miocene to Pliocene: Chunabati Formation) of Darjeeling, Eastern Himalaya. This epifoliar Siwalik fungal species is characterized by a dark brown, sub-dense mycelial mat; septate, branched, superficial, oppositely arranged hyphae with one to two-celled, alternate to oppositely arranged appressoria; flattened, circular, non-ostiolate thyriothecia, scutellum with radially arranged isodiametric to cylindrical cells; and bi-celled, one-septate, conglobate to ellipsoidal, striated ascospores. Here, we reconstruct for the first time a possible sexual life cycle of A. siwalika. The in-situ occurrence of Asterina on Calophyllum leaf cuticles suggests a warm and humid tropical climate and a possible host-parasitic relationship that might have existed in the ancient forest of the Darjeeling sub-Himalaya region during the time of deposition. The conclusion is supported by published qualitative and quantitative climatic data using plant megafossils recovered from the same fossil locality.

A Systematic Assessment of Greening Interventions for Developing Best Practices for Urban Heat Mitigation—The Case of Huế, Vietnam

The health of urban populations is increasingly at risk due to the amplification and chronification of urban heat stress by climate change. This is particularly true for urban environments in humid tropical climates, including many cities in Southeast Asia. It is also in these locations where increasing climatic risks may be exacerbated by urban growth, underscoring the need to develop effective mitigation strategies for strengthening urban resilience and supporting climate change adaptation. Conservation and widespread implementation of green infrastructure (GI) are regarded as one means to counter heat as a public health threat. However, for lower-income countries across Southeast Asia, such as Vietnam, knowledge gaps remain with respect to the effectiveness of greening interventions for heat mitigation. To address this gap, in the context of urban expansion in the humid tropical city of Huế, Vietnam, diurnal cooling potential and regulation of outdoor thermal comfort (OTC) within a wide, shallow street canyon were systematically assessed for selected elements of GI along a quantitative and qualitative dimension using ENVI-met. Tree-based interventions were found to be most effective, potentially decreasing UTCI by −1.9 K at the domain level. Although lower in magnitude, green verges and green facades were also found to contribute to OTC, with green verges decreasing UTCI by up to −1.7 K and green facades by up to −1.4 K locally. Potential synergistic cooling impacts were identified through a combination of GI elements. However, no scenario was found to decrease heat stress to zero or moderate levels. Substantially reducing heat stress may thus require further measures and a closer consideration of local morphological characteristics.

Elemental geochemistry of Cretaceous deposits in the Dahomey Basin (Nigeria): Implications for paleoclimatic and paleoenvironmental reconstructions

The Dahomey Basin, located in southwestern Nigeria, is an energy-rich frontier basin with sedimentary successions consisting of both (onshore) terrestrial and (offshore) marine deposits. Since the discovery of several bitumen seeps, tar sands, and oil and gas shows offshore the basin and the successful production of the Aje Field, the basin has gained immense interest from academia and industry. Nevertheless, surface and subsurface research focusing on paleoclimatic conditions, primary productivity, anoxic conditions, paleowater depth, and hydrodynamic influence in the Dahomey Basin is less documented. To reconstruct paleoenvironmental conditions, subsurface data from the Araromi-Obu (A1) and Idiobiolayo (A15) cores were used. The average chemical index of alteration (CIA) values ranging from 63.01 to 94.88 reflect varying degrees of weathering intensity in the sediment source area of the Cretaceous Araromi Formation. These values show a transition from relatively low to considerably high degrees of weathering in the source region of the Araromi Formation. The analysis of CIA values and Ga/Rb, Sr/Cu, Sr/Ba, Ca/Al, and 100*Mg/Al ratios suggests that the Araromi Formation was deposited in a brackish to marine environment.Furthermore, chemical alteration-sensitive geochemical indicators revealed prevailing warm, humid tropical climates during the late Cretaceous period, with likely minor arid intervals. In addition, the geochemical markers used (Ba/Al, U/Th, Ni/Co, authigenic uranium (Uau), P/Ti, and [(Fe2O3 + CaO + MgO)/(SiO2 + Al2O3)] indicate poor paleoproductivity for the Araromi Formation deposited in an oxygen-rich marginal to shallow marine environment. The upper Cretaceous period was characterised by fluctuating hydrodynamic circulation, with a weak hydrodynamic regime in core A1 and transitioning to strong hydrodynamic conditions in core A15. The inferred paleowater depth corresponds to the salinity measurements, with the A1 core displaying elevated salinity, indicating a greater depth compared to the A15 core, which was deposited in a shallower environment and displays lower salinity.

Unveiling Climate Trends and Future Projections in Southeastern Brazil: A Case Study of Brazil’s Historic Agricultural Heritage

The intricate relationship between climate and society in a given region demands a profound understanding of climate patterns, especially in agricultural areas like Diamantina, Minas Gerais (MG), recognized by the Food and Agriculture Organization (FAO) as the birthplace of the first Globally Important Agricultural Heritage System (GIAHS) in Brazil, situated in the southwest region of the country. Given the growing concerns about climate change, we conducted a meticulous analysis of the climatic characteristics of Diamantina-MG. To achieve this, we examined historical meteorological data from 1973 to 2022, employing the Mann–Kendall and Sen’s slope tests to analyze trends. Additionally, we utilized three global climate models (GCMs) under different shared socioeconomic pathways (SSPs) to predict future climate scenarios (2021–2100) based on the projections of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). Furthermore, we used Köppen and Thornthwaite climate classification methodologies to characterize both the current and future climate conditions of the region. Our results indicate that, historically, Diamantina-MG has experienced significant increases in minimum temperature, indicating a warmer climate in recent decades. For temperature, the projections show a consensus among models, projecting a continuous increase, potentially reaching up to 5.8 °C above the historical average temperature (19.2 °C) by the end of the century. Regarding rainfall projections, they show greater uncertainty, with discrepancies among models observed until 2060. However, specifically for the second half of the century (2060–2100), the models agree that there will be increases in annual rainfall. Regarding the climatic types of the region, we found that the current Köppen Cwb and Thornthwaite B3rB’3a’ classifications could shift to Aw and B1wA’a’, representing a humid tropical savanna climate with longer periods of water deficiency, considering the impacts resulting from increased air temperature and evapotranspiration. In summary, the study’s results indicate that climate changes are occurring and are likely to intensify in the Jequitinhonha Valley region, MG, in the future. The analysis of these data, from the perspective of the Brazilian GIAHS sustainability, reveals the importance of considering adaptation and mitigation measures to ensure the resilience of agricultural systems and local communities in the region that face these significant environmental changes.

A Comparative Model of Thermal Performances Between a Modern and Classic Habitat for A Hot and Humid Tropical Climate: Case of Guinea

The objective of this research is to carry out a comparative study between a classic habitat and a modern habitat in order to understand which of the two is more efficient for a humid tropical area. To do this, a digital modeling of the heat transfer phenomena in the different components of the habitat was highlighted for a habitat made of stabilized earth bricks, a roof made of transparent tiles, false ceilings made of rectangular panels containing phase change material, concrete floor and a classic habitat made from local materials is presented. To show the reliability of this study, we validated our habitat model integrating phase change material through an experimental study carried out by researchers B. ZIVKOVIC and I. FUJII. A study on the temperature distributions at the level of certain components of the habitat done, and the influence of the variation of certain parameters was highlighted to know the thermal behavior of the two habitats. Furthermore, a comparative study was performed between the interior and exterior temperatures of the south walls of habitats incorporating PCM and without PCM, which are the components most exposed to solar radiation whose maximum values are respectively 33°C and 34, 5°C and 33.15°C against 47°C. Keywords: Performances, thermal, bioclimatic, PCM, Tropical climate, Guinea.

Use of the HEC RAS model for the analysis of exceptional floods in the Ouémé basin

Abstract. The Ouémé River basin extends over almost half of Benin's territory, entirely located in a humid tropical climate. This river system includes a deltaic zone (delta of the Ouémé) known for its high agricultural potential and thus subject to a socio-economic development agenda. The Ouémé delta is facing recurrent floods that maintain rural agricultural population into a retrograding crisis with significant damages such as losses of properties. The objective of this study is to improve decision-making in the Ouémé basin through the simulation of exceptional floods using the HEC-RAS model. The HEC RAS model is a conceptual model, which works through mathematical and physical formulas to implement environmental phenomena for forecasting, understanding and analysis purposes. The model inputs used are basin GIS data, hydro-meteorological data, characteristics of existing hydraulic structures, etc. The targeted outputs include 1D/2D/3D view plans with support of satellite images, tables, graphs and curves. It is worth mentioning that the model provides outputs compatible with other tools, such as civil engineering (Civil 3D, Revit, Infraworks, etc.) and GIS, that help to expand the valorization fields. The implementation of the model in the Ouémé basin has made it possible to note: (i) that the recurring effect of losses and damages is justified by the settlement of the population on the river banks; (ii) that there is an important agricultural production in areas of high flood risk; (iii) that depending on the occurrence of the phenomenon, the flooded extent and the height of submersion remains variable, and more important for extreme flooding; (iv) about 12.07 % occurrence of river flood against 13.24 % for flash flood at a return period of 30 years. Moreover, it is very relevant to note that most of flood waters converge to the western part of the basin (an area with a low risk of flooding, stretched over 63.68 km2) and to the eastern part around the Damè-Wogon depression (an area at high risk of flooding, stretched over 10.49 km2).

Vulnerability Assessment of a Highly Populated Megacity to Ambient Thermal Stress

The urban ambient environment is directly responsible for the health conditions of millions of people. Comfortable living space is a significant aspect that urban policymakers need to address for sustainable planning. There is still a notable lack of studies that link the spatial profile of urban climate with city-specific built-up settings while assessing the vulnerability of the city population. Geospatial approaches can be beneficial in evaluating patterns of thermal discomfort and strategizing its mitigation. This study attempts to provide a thorough remote sensing framework to analyze the summer magnitude of thermal discomfort for a city in a tropical hot and humid climate. Spatial profiles of dry bulb temperature, wet bulb temperature and relative humidity were prepared for this purpose. A simultaneous assessment of various discomfort indices indicated the presence of moderate to strong heat stress to a vast extent within the study area. The central business district (CBD) of the city indicated a ‘danger’ level of heat disorder for outdoor exposure cases. Nearly 0.69 million people were vulnerable to a moderate threat from humid heat stress, and around 0.21 million citizens faced strong heat stress. Combing city morphology in the study showed that mid-rise buildings had the maximum contribution in terms of thermal discomfort. City areas with built-up cover of more than 68%, along with building height between 5.8 m and 9.3 m, created the worst outdoor discomfort situations. Better land management prospects were also investigated through a multicriteria approach using morphological settlement zones, wind direction, pavement watering, building regulations and future landscaping plans. East–west-aligned road segments of a total 38.44 km length were delineated for water spray cooling and greener pavements. This study is likely to provide solutions for enhancing ambient urban health.

Traditional Kerala Courtyard Houses: An Insight into Indoor Thermal Comfort within a Tropical Context

The indoor thermal environment holds a critical position within the realm of sustainable building practices, especially in the context of Kerala's warm and humid tropical climate. It plays a pivotal role in ensuring the comfort and well-being of occupants, making it a key consideration from the very inception of building design. This early emphasis on environmental concerns is essential for seamlessly integrating sustainability into the fabric of the building environment. The backdrop against which this emphasis on indoor thermal comfort occurs is the backdrop of global climate change, exemplified by the ongoing challenge of global warming. This phenomenon directly affects human comfort as a significant portion of our daily lives is spent indoors, engaged in various activities. As Kerala grapples with a growing urban population, the demand for additional housing, commercial spaces, offices, and amenities is on the rise. Modern-day occupants are increasingly cognizant of the pivotal role that sustainability plays in enhancing their overall quality of life. Central to this quality of life is the attainment of a favourable indoor thermal environment. This is especially true in residential settings, where the well-being and safety of residents are paramount. Global warming, with its rising temperatures and escalating greenhouse gas emissions, has wide-ranging repercussions for outdoor environments. In response, residential developments undergo transformations that alter urban climate dynamics. These changes are manifest in shifts in building materials, structural elements, and energy consumption patterns, all of which are driven by the economic activities of the human population. It is crucial to recognize that the indoor environment is intricately connected to external conditions. Therefore, understanding the factors that influence indoor thermal comfort is imperative when endeavouring to create a comfortable and health-promoting atmosphere within traditional Kerala courtyard houses. These factors encompass the microclimate of the site, including variables such as temperature, relative humidity, and wind patterns. These elements collectively contribute to the dynamic nature of the indoor thermal environment within these traditional tropical dwellings, underscoring the importance of considering them within the context of sustainability and comfort. Key Words: Vernacular Architecture, Thermal Comfort, Traditional Courtyard Houses, Climate Adaptation, Heritage.