Rain Season Research Articles

Extreme seasonal water-level changes and hydraulic modeling of deep, high-altitude, glacial-carved, Himalayan lakes

Himalayan lakes represent critical water resources, culturally important waterbodies, and potential hazards. Some of these lakes experience dramatic water-level changes, responding to seasonal monsoon rains and post-monsoonal draining. To address the paucity of direct observations of hydrology in retreating mountain glacial systems, we describe a field program in a series of high altitude lakes in Sagarmatha National Park, adjacent to Ngozumba, the largest glacier in Nepal. In situ observations find extreme (>12 m) seasonal water-level changes in a 60-m deep lateral-moraine-dammed lake (lacking surface outflow), during a 16-month period, equivalent to a 5 times 10^6 m^3 volume change annually. The water column thermal structure was also monitored over the same period. A hydraulic model is constructed, validated against observed water levels, and used to estimate hydraulic conductivities of the moraine soils damming the lake and improves our understanding of this complex hydrological system. Our findings indicate that lake level compared to the damming glacier surface height is the key criterion for large lake fluctuations, while lakes lying below the glacier surface, regulated by surface outflow, possess only minor seasonal water-level fluctuations. Thus, lakes adjacent to glaciers may exhibit very different filling/draining dynamics based on presence/absence of surface outflows and elevation relative to retreating glaciers, and consequently may have very different fates in the next few decades as the climate warms.

Cold Season Rain Event Has Impact on Greenland's Firn Layer Comparable to Entire Summer Melt Season

AbstractRainfall high on the Greenland Ice Sheet is an emerging phenomenon with consequences for the thermal and structural makeup of the surface layer. We document changes to Greenland's firn column due to a 4‐day cold‐season warm/rain event. Heavy precipitation occurred with a sudden 30°C increase in air temperature, reaching 0°C at 2,000 m elevation. Thermistor strings within the firn layer across a 35 km transect show rapid warming of 6°–23°C reaching depths of 2–10 m. Antecedent conditions governed the magnitude, duration, and depth‐distribution of sensible and latent heat added to the firn column. Heat fluxes from the firn layer required up to 8 weeks to recover to baseline, a significant fraction of the winter period. The amount of liquid water refrozen in the firn column was ∼20%–100% of the prior summer demonstrating the impact of extreme weather events on the ice sheet's evolution and runoff characteristics.

Climate variability and mining sustainability: exploring operations’ perspectives on local effects and the willingness to adapt in Ghana

The mining industry is susceptible to the effects of local climatic changes just as the surrounding socioecological systems are exposed to both mining and changing climate impacts. Adaptation deficit in mining is a worldwide problem but given the double exposure of surrounding systems, which has emergent outcomes on the industry, operations must adapt to coexist with surrounding rural communities. To understand this susceptibility, the study employed mixed methods to assess the implications of local climatic changes on mining sustainability as perceived among Ghanaian operations through the lens of the corporate adaptation process framework. The results indicate that operational workers are aware of increasing variability in the climatic patterns across southwestern Ghana, citing changes in the start/end of the rain season, torrential rain, prolonged dry season, and a general increase in temperature. The effects of these changing patterns, which affect mining activities, are diverse, including mine water management, safety, and occupational health issues as well as production planning opportunities. Workers ranked high the need to involve stakeholders such as the state-appointed regulators and Ghana Chamber of Mines as key strategies to enjoin adaptation to changing climate at operational sites. In addition, workers perceived the impact on regulatory and economic sustainability performances as major factors determining the industry’s perception and willingness to adapt. The study highlights pertinent issues useful for informed policy decision-making in the strive towards attaining sustainable development goals, especially Goal 13, which calls for active collaboration between business and society.

Precipitation timing and soil substrate drive phenology and fitness of Arabidopsis thaliana in a Mediterranean environment

Abstract In Mediterranean climates, the timing of seasonal rains determines germination, flowering phenology and fitness. As climate change alters seasonal precipitation patterns, it is important to ask how these changes will affect the phenology and fitness of plant populations. We addressed this question experimentally with the annual plant species Arabidopsis thaliana. In a first experiment, we manipulated the date of rainfall onset and recorded germination phenology on sand and soil substrates. In a second experiment, we manipulated germination date, growing season length and mid‐season drought to measure their effects on flowering time and fitness. Within each experiment, we manipulated seed dormancy and flowering time using multilocus near‐isogenic lines segregating strong and weak alleles of the seed dormancy gene DOG1 and the flowering time gene FRI. We synthesized germination phenology data from the first experiment with fitness functions from the second experiment to project population fitness under different seasonal rainfall scenarios. Germination phenology tracked rainfall onset but was slower and more variable on sand than on soil. Many seeds dispersed on sand in spring and summer delayed germination until the cooler temperatures of autumn. The high‐dormancy DOG1 allele also prevented immediate germination in spring and summer. Germination timing strongly affected plant fitness. Fecundity was highest in the October germination cohort and declined in spring germinants. The late flowering FRI allele had lower fecundity, especially in early fall and spring cohorts. Projections of population fitness revealed that: (1) Later onset of autumn rains will negatively affect population fitness. (2) Slow, variable germination on sand buffers populations against fitness impacts of variable spring and summer rainfall. (3) Seasonal selection favours high dormancy and early flowering genotypes in a Mediterranean climate with hot dry summers. The high‐dormancy DOG1 allele delayed germination of spring‐dispersed fresh seeds until more favourable early fall conditions, resulting in higher projected population fitness. These findings suggest that Mediterranean annual plant populations are vulnerable to changes in seasonal precipitation, especially in California where rainfall onset is already occurring later. The fitness advantage of highly dormant, early flowering genotypes helps explain the prevalence of this strategy in Mediterranean populations. Read the free Plain Language Summary for this article on the Journal blog.

Genomic Surveillance of Recent Dengue Outbreaks in Colombo, Sri Lanka.

All four serotypes of the dengue virus (DENV1-4) cause a phenotypically similar illness, but serial infections from different serotypes increase the risk of severe disease. Thus, genomic surveillance of circulating viruses is important to detect serotype switches that precede community outbreaks of disproportionate magnitude. A phylogenetic analysis was conducted on near full length DENV genomes sequenced from serum collected from a prospective cohort study from the Colombo district, Sri Lanka during a 28-month period using Oxford nanopore technology, and the consensus sequences were analyzed using maximum likelihood and Bayesian evolutionary analysis. From 523 patients, 328 DENV sequences were successfully generated (DENV1: 43, DENV2: 219, DENV3:66). Most circulating sequences originated from a common ancestor that was estimated to have existed from around 2010 for DENV2 and around 2015/2016 for DENV1 and DENV3. Four distinct outbreaks coinciding with monsoon rain seasons were identified during the observation period mostly driven by DENV2 cosmopolitan genotype, except for a large outbreak in 2019 contributed by DENV3 genotype I. This serotype switch did not result in a more clinically severe illness. Phylogeographic analyses showed that all outbreaks started within Colombo city and then spread to the rest of the district. In 2019, DENV3 genotype I, previously, rarely reported in Sri Lanka, is likely to have contributed to a disease outbreak. However, this did not result in more severe disease in those infected, probably due to pre-existing DENV3 immunity in the community. Targeted vector control within Colombo city before anticipated seasonal outbreaks may help to limit the geographic spread of outbreaks.

Effect of ventilation on thermal and humidity environment of the underground utility tunnel in the plum rain season in southern China: Field measurement and CFD simulation

The underground utility tunnel (UUT) is one of the typical urban underground structures, which usually requires mechanical ventilation systems for forced ventilation. In addition to the ventilation scheme for accident scenarios, the normal operating ventilation scheme deserves equal attention as it has a great impact on the air quality as well as the thermal and humidity environment inside the UUT. In this study, a UUT located in southern China is taken as the research object, and the effect of ventilation on its internal thermal and humidity distribution is explored with a combined use of field measurements and numerical simulations. The results of field measurements show that the average temperature inside the closed UUT is 20.5 ℃ and the average humidity ratio is 14.1 g/kgdry; both are lower than those of the external environment. In the plum rain season, if the tunnel is ventilated without any treatment of the external airflows, surface condensation tends to occur near the air inlet while the region with high relative humidity would be distributed on both sides far from the air inlet. The study also discusses the effect of different temperatures and humidity ratios of the inflow air on the humidity inside the UUT, and on this basis, the humidity control strategy for UUT in the plum rain season is proposed.

Tied-ridging and soil inputs enhance small-scale maize productivity and profitability under erratic rainfall conditions in central Kenya

Deficits in soil moisture and low soil fertility are the major constraints to smallholder farming systems in the SSA (sub-Saharan Africa) region. This study evaluated the effects of tied ridging and selected soil fertility inputs on; soil water content at different depths, maize yields, and economic returns. The treatments were: Tithonia diversifolia + inorganic fertilizer, manure + inorganic fertilizer, inorganic fertilizer, and control with or without tied ridging as the soil water conservation factor. Data were subjected to analysis of variance, and the means were separated using LSD at p ≤ 0.05. Treatments with Tithonia diversifolia or manure combined with inorganic fertilizer with or without tied ridging consistently affected soil water content positively. The effect of tied ridging on soil water content was greater during the short rain season compared to the long rains. In addition, there was evidence that tied ridging and organic soil inputs resulted in greater soil moisture conservation during the critical silking and tasselling maize phenological stages during the short rain season. Treatments had significant effects on grain and stover yields during the long rain 2016 season (p < 0.0001 and p = 0.0477, respectively) and the short rain 2016 season (p < 0.0001 and p = 0.0035, respectively). The highest (4.87 Mg ha−1) maize grain yield was recorded in Tithonia diversifolia plus inorganic fertilizer under tied ridging in the long rain 2016 season, while manure + inorganic fertilizer without tied ridging gave the highest yields (1.27 Mg ha−1) in the short rain 2016 season. The highest net benefits of US$ 1229.90 ha−1 and US$ 171.57 ha−1 were recorded under Tithonia diversifolia plus inorganic fertilizer with tied ridging during the long and short rain seasons, respectively. Overall, the best-performing treatments in yields and profitability were those that combined organic and inorganic fertilizers, regardless of the presence or absence of tied ridging. Climate-smart agricultural strategies combining tied ridges and organic inputs should be an integral component of farmer management if losses related to soil fertility and water stress are to be minimized under erratic rainfall regimes in the semiarid farming systems of the SSA region.

A multivariate statistical approach and water quality index for water quality assessment for the Rokel river in Sierra Leone

The main aim of the study was to use multivariate statistical approach to determine the relationship between parameters, identify the factors affecting the quality of water and interpret and group the water quality parameters. Water quality data was collected during two seasons; wet season spanning from June to August 2019 and dry season spanning from February to April 2019. The physiochemical and microbial parameters measured from the sampling process were turbidity, temperature, pH, electric conductivity, total hardness, calcium carbonates, total dissolved solid (TDS), dissolved oxygen (DO), total suspended solids (TSS), iron, nitrate, phosphate, potassium, sulphate, chromium, fluoride, e. coli and coliform. A total of 406 data set were collected and analysed using Principal Component Analysis, water quality index, cluster analysis and analysis of variance (ANOVA). These data sets were tested for sampling adequacy using Kaiser-Meyer-Olkin and Bartlett's Test and the result on the Kaiser-Meyer-Olkin Measure of Sampling Adequacy obtained was 0.615. The analysis yields Five PCs extraction with eigenvalues >1. These components explained 82.628% of the total variance of the entire components. The maximum water quality index 13 which indicated a grade A and can be treated for water supply. The following parameters Chromium 0.39 mg/l, Iron 1.88 mg/l, turbidity 18.66NTU, Phosphates 26.00 mg/l and fluorides 1.75 mg/l exceeded the WHO guidelines for drinking water. The mean values electrical conductivity is 12.26 μS/cm, 31.8 μS/cm for rain and dry seasons respectively., The following parameters Turbidity, Total Dissolved Solid, Total Suspended solids, Iron, Phosphate, Fluoride and Sulphate shows variation with High during the rain and low during the dry season with significant statical difference with a p value < 0.05. Whereas there is difference between the seasonal values of chromium, Nitrate and Potassium. The ANOVA resulted in P-value >0.05 which indicated no statistically significant different for chromium, Nitrate and Potassium. The seasonal variation was corroborated by cluster analysis with two clusters of C1 and C2. The PCs analysis, cluster analysis and ANOVA gave detailed characterization of the source and group correlation amongst the physiochemical and microbial parameters.

Dominant modes of precipitation over Africa, and their associated atmospheric circulations from observations

AbstractThis study uses the empirical orthogonal function (EOF) analysis to identify and describe continental‐scale seasonal (MAM, JJA, SON and DJF) precipitation modes over Africa based on observation (Global Precipitation Climatology Centre; GPCC) and reanalysis (ERA5) data from 1982 to 2014. Using composite analysis, we attempt to identify the atmospheric circulations (wind and relative humidity) associated with each precipitation mode. Precipitation from ERA5 has a good agreement with that of GPCC, as observed in the good spatial congruence in the EOF analysis and precipitation composites. The EOF results for each season show that the loading patterns of Mode 1 (variance &gt;20% for all seasons) match the long‐term mean precipitation distribution. Atmospheric conditions across the continent are primarily driven by the four main high‐pressure systems (Azores, St. Helena, Arabian and Mascarene High) that influence moisture distribution and subsequently modulate the seasonal rain belt distribution. Modes 2 (variance &gt;11% for all seasons) and 3 (variance &gt;10% for all seasons) are deviations of the leading mode associated with smaller‐scale atmospheric systems. However, large‐scale factors still dominate the overall precipitation pattern by modulating the seasonal energy transfer between the hemispheres. The results provide a comprehensive understanding of the continental‐wide African seasonal precipitation modes and the associated atmospheric circulation from observations. The findings can be used as a reference for future work using model data for historical and projection studies.

Phenophase-based comparison of field observations to satellite-based actual evaporation estimates of a natural woodland: miombo woodland, southern Africa

Abstract. The trend and magnitude of actual evaporation across the phenophases of miombo woodlands are unknown. This is because estimating evaporation in African woodland ecosystems continues to be a challenge, as flux observation towers are scant if not completely lacking in most ecosystems. Furthermore, significant phenophase-based discrepancies in both trend and magnitude exist among the satellite-based evaporation estimates (i.e. Global Land Evaporation Amsterdam Model (GLEAM), moderate resolution imaging spectroradiometer (MODIS), operational simplified surface energy balance (SSEBop), and water productivity through open-access remotely sensed derived data (WaPOR)), making it difficult to ascertain which of the estimates are close to field conditions. Despite the many limitations with estimation of evaporation in woodlands, the development and application of the distributed temperature system (DTS) is providing deepened insights and improved accuracy in woodland energy partitioning for evaporation assessment. In this study, the Bowen ratio distributed temperature sensing (BR-DTS) approach is used to partition available energy and estimate actual evaporation across three canopy phenophases of the miombo woodland, covering the entire 2021 dry season (May–October) and early rain season (November–December) at a representative site in Mpika in Zambia, southern Africa. To complement the field experiment, four satellite-based evaporation estimates are compared to the field observations. Our results show that actual evaporation of the miombo woodland appears to follow the trend of the net radiation, with the lowest values observed during the phenophase with the lowest net radiation in the cool dry season and the highest values during the phenophase with peak net radiation in the early rainy season. It appears the continued transpiration during the driest period in the dormant phenophase (with lowest canopy cover and photosynthetic activities) may be influenced by the species-dependent adapted physiological attributes such as access to moisture in deep soils (i.e. due to deep rooting), plant water storage, and the simultaneous leaf fall and leaf flush among miombo plants. Of the four satellite-based evaporation estimates, only the WaPOR has a similar trend to the field observations across the three phenophases. However, all four satellite-based estimates underestimate the actual evaporation during the dormant and green-up phenophases. Large coefficients of variation in actual evaporation estimates among the satellite-based estimates exist in the dormant and green-up phenophases and are indicative of the difficulty in estimating actual evaporation in these phenophases. The differences between field observations and satellite-based evaporation estimates can be attributed to the model structure, processes, and inputs.

Shading Stress at Different Grain Filling Stages Affects Dry Matter and Nitrogen Accumulation and Remobilization in Fresh Waxy Maize.

Shading stress caused by plum rain season, which overlapped with grain filling process of fresh waxy maize in Southern China, significantly affected crop productivity. In order to investigate the effects of shading at different stages after pollination on the yield, accumulation, and remobilization of dry matter and nitrogen (N) in fresh waxy maize, field experiments were conducted, including shading at 1-7 (Z1), 8-14 (Z2), 15-21 (Z3), and 1-21 (Z4) days after pollination in 2020 and 2021. The results showed that shading reduced the fresh ear and grain yield and increased moisture content in Suyunuo5 (SYN5) and Jingkenuo2000 (JKN2000) compared to natural lighting treatment (CK). The ear yield decrease was more severe in Z4 (43.5%), followed by Z1 (29.7%). Post-silking dry matter and N accumulation and remobilization were decreased under shading stress, and those were lowest in Z4, followed by Z1. The remobilization of pre-silking dry matter and N were increased by shading stress, and the increase was highest in Z4, followed by Z1. The harvest index of dry matter and N was lowest in Z4 and second-lowest in Z1. In conclusion, shading decreased yield by affecting accumulation and remobilization of post-silking dry matter and N, and the impact was more serious when it introduced early during grain filling stage in fresh waxy maize production.

Assessing the Current Status and Proposing Solutions for Heavy Metal Management in the Saigon River Basin Sediments

The sediment is the final environment where heavy metals accumulate and directly impact the health of aquatic systems and humans.Therefore, the study was carried out to determine the total content and forms of heavy metals in the sediments at 13 locations in the Saigon River basin in rain and dry seasons of 2022. In addition, this research also assesses the pollution risk level and the correlation between heavy metals and physicochemical properties in the sediments. Chemical analysis was applied to determine the contributors of heavy metals while the geochemical calculation methods (hazard quotient (HQ), geo-accumulation index (Igeo), pollutant load index (PLI), individual contamination factors (ICF) and global contamination factors (GCF), risk assessment code (RAC)) were used to assess the pollution risk level in river sediments. The results show that Ag, Ba, Mn and Zn were metals with high pollution risks, especially in rain season. The results showed that the total concentration of heavy metals in sediments in rain season ranges from 109.92 to 4591.01 mg.kg–1 (Mn &gt; Zn &gt; Li &gt; Ba &gt; Ag &gt; Cr &gt; Cu &gt; Pb) and in dry season from 0 to 3117.8 mg.kg–1 (Mn &gt; Ag &gt; Zn &gt; Li &gt; Ba &gt; Cr &gt; Cu &gt; Pb). Applying the sequential extraction method, the metal forms of Ba, Cr, Cu and Li in the sediment samples are mainly residues (F5) (up to 76.53%), proving these elements dominated by natural sources. In contrast, the Mn extract composition was strongly influenced by human activity with exchange (F1) (&gt;50%) and carbonate (F2) (&gt;20%) components predominating. For Ag, Pb and Cu were mainly in organic form (F4). In dry season, the river sediments didn’t contain Pb because it didn’t carry away rainwater. In particular, Zn had a strong fluctuation between the extracted forms in rain and dry seasons, showing impacts from nature and humans sources. Besides, the statistical analysis results showed that pH affected Cu and Zn contents with a negative correlation, but did not detect the correlation between heavy metals and sand, clay, electrical conductivity (EC) in Saigon river sediments. The research results are foundational for the implementation and design of effective remediation strategies to prevent risks of river sediments degradation in the future.&#x0D; &#x0D;

Bioclimatic zoning for quails in the rain season in the state of Paraíba, Brazil

This work aimed to perform bioclimatic zoning based on the temperature and humidity index (THI) for quails from the 3rd to the 5th week of life during the rainy season in the state of Paraíba, Brazil, in order to identify the most suitable mesoregions among the Zona da Mata, Agreste, Borborema and Sertão for the breeding of these birds and to propose mitigating measures for the thermal comfort of the animals. The monthly air temperature and relative humidity data for calculating the THI were obtained from conventional meteorological stations of the National Meteorological Institute of the Brazilian federal government from 1961 to 2015, in turn making maps with the spatial distribution of the index. The index ranged from 71 to 76 in the various mesoregions of Paraíba, with Agreste being the best mesoregion for breeding quails from the 3rd to the 5th week of life, thus providing a thermal comfort zone for birds and only requiring a few corrective measures in their facilities, when necessary, followed by the Sertão, Zona da Mata and Borborema mesoregions.

Perception of climate change and coping strategies among smallholder irrigators in Zimbabwe

IntroductionAcross sub-Sahara Africa, governments and international aid agencies are making huge investments in smallholder irrigation schemes to enhance food security, climate resilience and economic transformation in rain-fed farming systems. Unfortunately, a majority of the smallholder irrigation schemes have performed dismally on these fronts. Climate change is a major exacerbating factor to existing challenges resulting in the poor performance of the schemes. Hence, it is crucial to understand smallholder irrigators' perceptions of climate change and current adaptation strategies to co-design appropriate and acceptable adaptation strategies to address water stress in the schemes. This area had received less significant research attention. This study aims to determine the perception of climate change and coping strategies in smallholder schemes.MethodsA mixed-method research strategy was used to collect data from 317 irrigation scheme farmers in three schemes (Exchange, Insukamini, and Ruchanyu) in Midlands Province. A binary logistic regression (BLR) method was used for data analysis.ResultsThe results suggest that scheme farmers have noticed changes in temperature and rainfall patterns. Results obtained from the model show that climate change perception was mainly influenced by age, gender, location, irrigation experience, and plot size. Farmers perceived that climatic change has resulted in decreased irrigation water availability, thus leading to poor yields. This study also shows that the main adaptation strategies to water stress include improving soil moisture conservation, construction of small-scale reservoirs, water charging and trade, setting clear water use priorities, and adoption of climate-resilient and short-season crop varieties. Perception of high temperatures, long dry periods, late rainfall, increase in the frequency of drought, shortening of cold season, and shortening of rain season influence adaptation strategies adopted by scheme farmers.ConclusionThis study offered useful data for policymakers and irrigation developers to develop appropriate policies and programs to improve the sustainability of schemes given current and projected water stress in Zimbabwe and sub-Sahara Africa in general.

Global neurology: It's time to take notice.

Global neurology: It's time to take notice.

Characterization of seawater intrusion dynamics under the influence of hydro-meteorological conditions, tidal oscillations and melioration system operative regimes to groundwater in Neretva valley coastal aquifer system

Study regionRiver Neretva coastal aquifer system located in the south eastern part of Croatia. Study focusThe study is focused to determination of the seasonal and non-seasonal variations of the groundwater features, when influenced by external loadings found at the study area. Based on time series observed from the monitoring systems, in-situ profiling and observed external loadings, a spectrogram and coherence analysis is performed to detect the peculiarities of the groundwater regimes at three different subareas along the study area. New hydrological insights for the regionBy using several methodological approaches, this paper emphasizes the combined effects of precipitation, river Neretva hydrological regime, melioration system operational regimes and tidal effects to the groundwater regime during the dry and rain seasons. During the dry period groundwater regime is mainly influenced by the seawater intrusion directly from the sea and from the river Neretva bed. Rain periods are characterized by the increase of the Neretva discharge thus eliminating the seawater from the river bed. This scenario results in improved quality of the groundwater. While Diga subarea faces active seawater intrusion, Jasenska's unconfined aquifer is fed by seawater from the river Neretva during the dry season. Vidrice is the only area where groundwater quality decreases during rain season due to the presence of salinized springs and the fact the area is found below the mean sea level.

Impact of soil erosion on water treatment cost: Case of Gihira water treatment plant, Rubavu, Rwanda

The study aimed to assess the impact of soil erosion on cost of Gihira Water Treatment Plant (GWTP). Raw water and treated data were gathered from GWTP in different seasons (rain and dry season). The parameters such as TSS, Turbidity and E.coli were determined with standard methods. Documentary review was used to collect data related to annual rainfall, elevation, soil texture, land use and vegetation cover. The results revealed that heavy rainfall impacted negatively quantity of water produced at GWTP with rate of 6.8%, 10.80% and 6.67% in March, April to May and1.57%, 1.73% and 1.66% in June, July and August in 2017. In 2018, the rates of 12.09%, 5.57% and 4.76% in March, April and May and the rates of 1.81%, 1.09% and 1.93% in June, July and August were recorded. The same situation was reproduced in 2019, where the rates were 8.09%, 4.76% and 4.76% in rain season against of 1.38%, 0.85 and 0.55% of dry season. The findings revealed that a high disturbance of the water treatment occurred during the rainy season due to agriculture practices and high steep slope of the areas which lead to high rate of soil erosion in the catchment and more chemicals were used to treat potable water than in dry seasons.

Comprehensive Case Study on the Ecologically Sustainable Design of Urban Parks Based on the Sponge City Concept in the Yangtze River Delta Region of China

Owing to widespread urbanization, previously elastic and permeable ecological foundations are being continuously hardened, sealed, and channelized, leading to problems such as intensified urban convergence, water pollution, seasonal rain, and flood disasters. Urban parks and large green spaces, as rare large, cavernous bodies in cities, can effectively address the abovementioned urbanization problems. This study holistically analyzed and discussed the current developments in the sponge city concept using several case studies of recent ecologically sustainable designs for urban parks in the Yangtze River Delta region of China. Under basic conditions of the same hydrological characteristics and considering the differences in other external conditions and the environment, sponge city construction aims to address the actual characteristics and needs of specific projects, develop applicable goal-oriented sponge city constructions, and ensure design practices around a goal-oriented method. Practical problems associated with identifying specific design features, priorities, and measures were then identified according to the project location, goals, and characteristics. Thus, this study details various goal-oriented sponge city designs and their application methods to inform future design efforts.

Characteristics of Raindrop Size Distributions in the Southwest Mountain Areas of China According to Seasonal Variation and Rain Types

The precipitation and raindrop size distribution (RSD) characteristics of the four seasons and different rain types were studied using a PARSIVEL2 raindrop disdrometer set in the southwest mountain areas of China from 2019 to 2021. The seasonal precipitation in the southwest mountain areas was mainly stratiform rain. The peaks of the RSD were about 1–2 orders of magnitude higher than those in the plains. The convective rain in spring and autumn was very close to the ocean-like convective mass. The local shape–slope (μ–Λ), radar reflectivity–rain rate (Z–R), and kinetic energy–rain rate (KE–R) relationships were further derived, and the diversity of these relationships was mainly due to the variability of the RSDs. In addition, the differences in the RSD characteristics between the top and the foot of the mountain during a typical precipitation process in the summer of 2020 were further compared. It was found that the number density of the small particles at the top of the mountain was higher than that at the foot of the mountain due to the broken large raindrops caused by the high wind speed, while the high evaporation rate, strong convective available potential energy (CPAE), and water vapor content at the foot of the mountain could strengthen the RSD, making the number density of the large raindrops at the foot of the mountain higher than that at the top.

Extreme Flood Levels during the Operation of Cascade Reservoirs: A Case Study of the Lower Yangtze River in 2020

Flood disasters related to climate change are becoming increasingly frequent, indicating the potential for repeated future incidence. It is essential to fully understand the causes and mechanisms of flood formation to reduce future losses. By taking the extreme flood in the lower Yangtze River in 2020 as an example and using hydrological and rainfall data of the basin, the formation process and triggering factors of a flood disaster were analyzed in this study. The flooding process can be divided into six typical stages, in which the long duration plum rain season, frequent and high-intensity rainstorms, and high overlapping rainfall areas are the preconditions for flood formation, whereas frequent encounters of floods in the main stream and tributaries of the middle and lower Yangtze River are the decisive factors. In addition, flood drainage along the lower reaches and the jacking effect of the downstream tide level play a role in promoting flooding. During this process, the joint operation of cascade reservoirs plays a key role in the prevention of catastrophic floods. The aforementioned results can provide a reference for flood control strategies in case of similar floods in the future.