Natural Rain Research Articles

Sound of natural and artificial rain impact on ETFE membranes

Thin membranes are known to produce a drum-like effect when subjected to rainfall. Rain noise affects acoustic comfort and might disrupt communication, speech intelligibility and cognitive task performance. Therefore, assessment of the characteristics of noise produced by impact of rain on membranes in different architectural settings is important. Given inherent disparities between natural and artificial precipitation-primarily in terms of droplet size distribution and terminal velocities-underscores the importance of conducting evaluations using natural rain noise. The focus of this study is on the comparative assessment of the sound generated by natural rainfall versus the sound generated by the impact of individual droplet in a semi-anechoic room on single Ethylene tetrafluoroethylene (ETFE) membranes. The study assesses the extent of spectral variations of the rain sound produced in both approaches and the corresponding absolute value of noise intensity.

Plant litter as a heavy metal migration strategy following application of sewage sludge to subtropical forest soils

The environmental risks of migration of heavy metals (HMs) following applications of sewage sludge (SS) to forest soils are garnering increased attention. Plant litter at the forest floor may modify HM migration pathways through impacts on soil aggregates and water/soil erosion; however, HM migration responses to plant litter are poorly understood. The aim of this study was to determine the effects of plant litter cover on HMs migration, and water and soil erosion following the application of SS to subtropical forest soils. Effects of addition of SS along and SS plus plant litter at 0.75 or 1.5 kg m−2 on the migration of cadmium, chromium, copper, nickel, lead, and zinc in surface runoff, soil interflow, and sediments were quantified across nine simulated rainfall events in a laboratory experiment and following natural intense rain events in a field experiment. Addition of SS elevated HM concentrations in surface runoff by 38.7 to 98.5 %, in soil interflow by 48.3 to 312.5 %, and in sediment by 28.5 to 149.4 %, and increased the production of sediment aggregates <0.05 mm that led to greater cumulative migrations of HMs in surface runoff and sediment; sediment accounted for 89.5 % of HM migrations. Addition of plant litter reduced cumulative migration of HMs by 87.1–97.27 %; however, the higher rate of plant litter led to a decrease in surface runoff and sediment yield, and an increase in soil interflow. Addition of plant litter shifted the main pathway of HM migration from sediment to surface runoff and soil interflow. The potential ecological HM risk index was “low” for each treatment. We found consistency in HM concentrations and migrations via surface runoff between the field and laboratory experiments. Overall, the addition of plant litter with SS mitigated soil erosion and reduced total migration of HMs, resulting in a 88.7–97.3 % decrease in the ecological risk index of the six HMs. We conclude that the addition of plant litter may provide a management strategy for the mitigation of HM risks to environmental safety for the disposal of SS in subtropical forest systems.

Biochar reduces antibiotic transport by altering soil hydrology and enhancing antibiotic sorption

The performance of biochar (BC) in reducing the transport of antibiotics under field conditions has not been sufficiently explored. In repacked sloping boxes of a calcareous soil, the effects of different BC treatments on the discharge of three relatively weakly sorbing antibiotics (sulfadiazine, sulfamethazine, and florfenicol) via runoff and drainage were monitored for three natural rain events. Surface application of 1 % BC (1 %BC-SA) led to the most effective reduction in runoff discharge of the two sulfonamide antibiotics, which can be partly ascribed to the enhanced water infiltration. The construction of 5 % BC amended permeable reactive wall (5 %BC-PRW) at the lower end of soil box was more effective than the 1 %BC-SA treatment in reducing the leaching of the most weakly sorbing antibiotic (florfenicol), which can be mainly ascribed to the much higher plant available and drainable water contents in the 5 %BC-PRW soil than in the unamended soil. The results of this study highlight the importance of BC’s ability to regulate flow pattern by modifying soil hydraulic properties, which can make a significant contribution to the achieved reduction in the transport of antibiotics offsite or to groundwater.

Rain splash-mediated dispersal of Escherichia coli from fecal deposits to field-grown lettuce in the mid- and south Atlantic U.S. regions is affected by mulch type.

Wildlife feces can contaminate vegetables when enteric bacteria are released by rain and splashed onto crops. Regulations require growers to identify and not harvest produce that is likely contaminated, but U.S. federal standards do not define dimensions for no-harvest zones. Moreover, mulching, used to retain soil moisture and maximize crop yield may impact rain-mediated bacterial dispersal from feces. To assess Escherichia coli dissemination from a fecal point source to lettuce grown on various mulches, lettuce cv. 'Magenta' was transplanted into raised beds with plastic, biodegradable plastic, straw, or left uncovered at field sites in Maryland and Georgia. Eleven days post-transplant, 10g of rabbit manure spiked with ~8 log CFU g-1 E. coli were deposited in each bed. One day following natural or simulated rain events, lettuce was sampled along 1.5m transects on either side of fecal deposits. Lettuce-associated E. coli was semi-quantified with an MPN assay and dependence on fecal age (stale or fresh), lettuce age (baby leaf or mature head), distance from point source, mulch and post-rain days were statistically evaluated. Distance (p<0.001), fecal age (p<0.001) and mulch (p<0.01) were factors for E. coli transfer from point source to lettuce. The highest and lowest E. coli estimates were measured from lettuce grown on biodegradable plastic and straw, respectively, with a 2-log MPN difference (p<0.001). Mulch and distance were also significant factors in E. coli recovery 3 days post-rain (both p<0.001), where plastic mulches differed from bare ground and straw (p<0.01). For all treatments, fewer E. coli were retrieved from lettuce at 0.3m, 3 days post-rain compared to 1 day (p<0.001). Fitting the data to a Weibull Model predicated that a 7-log reduction in E. coli from fecal levels would be achieved at 1.2-1.4m from the point source on plastic mulches, 0.75m on bare soil (p<0.05) and 0.43m on straw (p<0.01). Straw and bare ground limited rain-mediated E. coli dispersal from feces to lettuce compared to plastic mulches. Fecal age was negatively associated with E. coli dispersal. These findings can inform harvesting recommendations for measures related to animal intrusion in vegetable production areas.

Experimental effect of wind and heavy rain on increased splash erosion using rainfall simulator

To investigate the erosion process that occurs, rainfall simulation is used with a model scale for natural rain events in laboratory conditions. The calculation of erosion and any soil erosion with a slope setting of 5% was carried out experimentally on a laboratory scale using a rain simulator and adding wind using a 2-inch snail blower. Experiments carried out in the laboratory included erosion tests driven by rain and erosion tests by rain, which were given additional wind variables. Rain intensity used for testing is using discharge 1 litre/minute,1.5 litre/minute, and 2 litre/minute as a representative variation of rainfall. The occurrence of rain and wind simultaneously within a certain period will cause greater loss of soil. Although many studies have been conducted on the effects of rain and the combined effects of wind on soil erosion, only a limited number of studies have focused on the combination of the two variables that occur together. The results showed that in the applied rain intensity and wind factor, the collision of the kinetic energy of the rain driven by the wind resulted in higher erosion when compared to that without the influence of the wind.

A Method of Detection and Identification for Axillary Buds

During the period from sowing and planting to harvesting, outdoor crops are directly affected by the natural environment, including wind, rain, frost, and sunlight. Under such circumstances, vegetables change their growth conditions, shape, and flexibility daily. We aimed to develop an agricultural work-support robot that automates monitoring, cultivation, disease detection, and treatment. In recent years, many researchers and venture companies have developed agricultural harvesting robots. In this study, instead of focusing on intensive harvesting operations, we focused on daily farm operations from the beginning of cultivation to immediately before harvest. Therefore, gripping and cutting are considered basic functions that are common to several routine agricultural tasks. To find the assumed objects from a camera image with a low computational load, this study focuses on branch points to detect and identify even if the stems, lateral branches, and axillary buds are swaying in the wind. A branch point is a characteristic part close to the working position, even when the wind blows. Therefore, we propose a method to detect the assumed branch points simultaneously and divide each branch point into the main stem, lateral branch, and axillary bud. The effectiveness of this method is demonstrated through experimental evaluations using three types of vegetables, regardless of whether their stems are swaying.

On collisional drop breakup in orographic rain

Collisional drop breakup is one of the important processes during evolution of the rain drops and leads to modified shape of the drop size distribution (DSD), which is a primary parameter in rain retrieval in remote sensing techniques. Though several experimental and observational studies have been performed in the recent past on this aspect, the impact of the same in natural rain, particularly in orographic rain, is still poorly represented. The present study aims to examine and identify the rain conditions in which collisional drop breakup is prominent and is capable of modifying the shape of DSD in orographic rain over north-eastern India. The 2-min averaged DSDs from four hilly locations are studied in both stratiform and convective rain types separately using ground-based DSD measurements. Even though drop breakup in intense to moderate rain seemed to be in notable percentage (0.2% - 11.2%), the low intensity rain also showed a considerable break-up signature (2.5% - 9%), depending upon the locations. The overall results showed that collisional breakup was more prominent in convective rain (1%–11%) than in stratiform rain (4%–5%), however, breakup is also seen primarily during stratiform rain in two of the locations. The Z-R coefficients are found to be significantly different for the break-up and non-break up cases. For breakup cases, both convective and stratiform rainfall shows an increase in intercept parameter for all locations. For stratiform rain types, the coefficient a and b ranged from 307.6 to 321.4 (167.1–178.7) and 1.27–1.37 (1.31–1.34) for rain with break-up (without break-up), respectively. In the case of convective rain, the coefficients were found to be in the range of 377.5–654.7 (270.4–641.3) and 1.28–1.42 (1.14–1.31) with break-up (without break-up), respectively. The results suggest that collisional breakup is an important process in orographic rain over North-Eastern India and it has to be taken care of, while studying rainfall over these regions, particularly in conventional radar derived quantitative precipitation estimates (QPE).

Methods for quantifying rain-splash dispersal of Neonectria ditissima conidia in apple canopies

Many microorganisms can be dispersed by rain-splash, whereby spores become suspended in water and are spread via droplets. The resulting dispersal gradient is dependent on several factors including rainfall intensity, the nature of the plant canopy and its effects on splash, deposition, redistribution (secondary splash) and filtering. Gradients of spore dispersal with distance are important for understanding epidemics, and the primary dispersal gradient can shape an epidemic for several pathogen generations. However, microorganisms are difficult to trap, identify and enumerate efficiently. This makes it difficult to study the spread and dispersal of pathogens to aid in biosecurity responses and management of epidemics. We used macroconidia of Neonectria ditissima, the causal organism of apple canker, to explore patterns of rain-splash dispersal in tree canopies. We investigated the use of a fluorescent tracer dye, PTSA (1,3,6,8-pyrenetetrasulfonic acid), as a surrogate to conidia capture during natural and artificial rain events, and lens tissue as ‘surrogate leaves’ to recapture tracer dye. Conidia and dye were released from central point sources 2.5 m above the ground and recaptured in passive rainwater traps or artificial ‘leaves’. Quantile regression and exponential models were used to explore variation and dispersal gradients derived for both conidia and dye, with and without tree canopy and with natural or artificial precipitation. Estimated dispersal gradients were steeper with a flatter tail when no tree canopy was present, whereas presence of tree canopy resulted in more variation and shallower predicted dispersal gradients, with fatter tails, predicting potential dispersal to further distances from the source. The majority of conidia and dye were recaptured at less than 1 m from the source, but small concentrations of spores were detected up to 3 m and dye more than 6 m. High variation in natural conditions requires further investigation to fully quantify natural dispersal gradients. Nevertheless, these results show the merit of tracer dye, artificial leaves, and quantile regression as tools to estimate potential dispersal patterns of N. ditissima and other rain-splash dispersed microorganisms, considering rain-splash factors in real canopies and natural situations for predicting inoculum dispersal.

Humidification Degree Effect under Rain of Inclined Silicone Insulation on its Electric Performance

This investigation is focused on the effect of inclination angle with respect to the horizontal of a hydrophobic silicone insulation, on the rate of its creepage distance's wetting by natural rain. The constellation of rainwater drops obtained on the de-energized site is then reproduced in the laboratory, to quantify the effect of their volume on the humidification intensity of the inclined insulation's creepage distance, and therefore its electrical performance under different alternating voltage levels. For this purpose, two different experimental devices allowing the variation of the insulation's inclination angle were set-up. The first one is dedicated to the on-site display of silicone samples in natural rain. The second one allows the study of the applied voltage's effect on the wetting degree of the insulation's surface. All the performed tests were supported by camera visualization. On-site measurement results show a decline in the length of the creepage distance of the natural rain-wetted insulation with increasing its inclination angle. Laboratory results also show a decrease in the size of the insulation's wet surface with increasing its inclination angle. These two characteristics reveal two different intervals of critical inclination angles of the insulation, unfavorable and favorable, for the dimensioning of the insulators' sheds corresponding respectively to their minimum and maximum electrical performance.

Viability of Artificial Rain for Air Pollution Control: Insights from Natural Rains and Roadside Sprinkling

Artificial rain, a technology primarily used for drought relief, has recently been used for combating regional air pollution. However, there are limited available measurement data to confirm the effectiveness of this control practice. In this study, we summarize control theories and indirect but relevant observations/findings, including air pollutant reduction after natural rain events and roadside sprinkling. A brief review of artificial rain basics is also provided. Our work shows that artificial rain appears to be a promising management strategy for air pollution control. However, field measurements are needed to further assess the cost-effectiveness of the practice, as well as the other benefits or challenges it may create.

Sediment modeling using laboratory-scale rainfall simulator and laser precipitation monitor

The characterization of a rainfall simulator provides an excellent opportunity to study the potential of soil erosivity without waiting for natural rain. But, precise instrumentation is required to estimate the parameters, which is seldom available. To overcome this problem, the empirical and conceptual relationships obtained through physically-based modeling help to correlate the rain parameters contributing to soil erosion. The present laboratory study used five pressurized nozzles of different capacities and a Laser Precipitation Monitor (LPM) to generate different rain intensities (21.0–79.0 mm h−1) and to register drop size distribution, respectively. The sediment transportation induced by rain and runoff was measured with an erosion flume of 2.50 × 1.25 × 0.56 m with an adjustable longitudinal slope. The spatial uniformity, drop size distribution, drop velocity, and kinetic energy were used to evaluate the simulator's performance. The different rain erosivity parameters were correlated and tested statistically using linear and non-linear regression analysis. The rain simulation experiments of different intensities at different pressure ranges were performed on flat, 5, 10, and 15% slopes of the erosion flume to evaluate rain characteristics and record the surface runoff and sediment yield. The median drop sizes produced during the simulator ranged from 0.38 to 2.11 mm, coinciding with natural rain. The empirical relationships were developed to correlate surface discharge and sediment yield with rain intensity by optimizing the parameters for further study of experimental field plots of different slopes. The observed and estimated rain erosivity parameters showed a significant relationship (R2 = 0.75 to 0.93; P < 0.001) in multiple regression analysis, and the metrics used to test the developed regression equations showed lower MAE, MSE, and RMSE errors indicating the adequacy of the relationships. The results indicated that the simulator helps to understand the complex task of soil erosion with hydrologic and geomorphic processes in laboratory experimentation with sufficient accuracy in measuring sediment transport events.

Evaluation of Soil Physico-Chemical Properties in Pre and Post Flood Conditions at Thatta Sindh Pakistan

The heavy rainfall caused biggest ever natural rain flood in River Indus in the history of Pakistan during 2010. The deltaic district Thatta of Sindh Pakistan hit by flood with breach came out at Dyke near Thatta city on right bank of River Indus. The soil sampling was carried out in month July 2010 prior to flood for routine soil analysis. After flood again soil samples from 13 same sites of pre flood spots were collected at two depths, 0-15 and 15-30 cm. Aim was to observe soil physic-chemical properties and nutrient status of pre-flood and post flood conditions. Soil sand pH and SAR were found significantly higher in post-flood conditions whereas clay and OM were found high in pre-flood conditions. The nutrients status of N, P, Ca and Mg were depleted however K remained satisfactory in post-flood conditions. In post flood conditions the pH and SAR were positive and significantly correlated with each other indicated disperse of soil. The information obtained from this study will be helpful to develop flood qualification strategies and proper management of soil.&#x0D;

Evaluation of small pod pepper varieties (Capsicum frutescens L.) at Kellem Wellega and West Wellega zones

Small pod hot pepper (chili pepper) is a seasonal plant of the family Solanaceae. It is grown as an annual crop and produced for its fruits (pods). It is one of the most important vegetable crops for fresh consumption (as chilies), for processing and as a spice (for making stew)and it the main source of income. A field experiment was conducted at Haro Sabu on station and Meti (Sayo Woreda) sub sites of Kellem Wollega zone, Western Ethiopia, during the 2018/2019 and 2019/2020 main cropping season. A total of five small pod hot pepper varieties collected from Melkasa and Bako Agricultural Research centers and one local check variety were used as testing materials. The combined analysis of variance (ANOVA) for total yield and other agronomic traits of six small pod hot pepper varieties grown at two locations revealed significant difference on days to flowering, days to maturity, number of primary branches per plant, number of fruit (pods) per plant, fruit diameter, fruit length and fruit weight total pod dry weight. Likewise there was highly significant difference of variety on pod anthracnose and cercospora leaf spot (frog eye). In this experimentation, Melka Oli and Melka Dera Dinsire varieties were found superior in terms of total dry pod yield and other important yield related parameters. Melka Oli and Melka Dera varieties are also tolerant to major hot pepper diseases. Thus these varieties were recommended for demonstration and wider production in the studied areas and similar agro-ecologies in the Western Oromia in particular and hot pepper producing regions of Ethiopia in general under main natural rain fed condition.

Unmanaged vegetated roofs hydrological performance in subtropical areas: An investigation in São Paulo, Brazil

Extensive vegetated roofs are Nature-based Solution with the ability to manage rainwater runoff in densely built spaces. Despite the large amount of research demonstrating its water management abilities, its performance is poorly quantified under subtropical climates and when using unmanaged vegetation. The present work aims at characterizing the runoff retention and detention of vegetated roofs under the climate of São Paulo, Brazil, accepting the growth of spontaneous species. By using real scale prototypes under natural rain, a vegetated roof hydrological performance was compared with a ceramic tiled roof. By using models with different substrate depths under artificial rain, changes in the hydrological performance were monitored for different antecedent soil moisture contents. Results from the prototypes showed that the (i) extensive roof attenuated from 30 % up to 100 % the peak rainfall runoff; (ii) delayed the peak runoff from 14 up to 37 min and (iii) retained from 34 % up to 100 % the total rainfall. Furthermore, results from the testbeds indicated that (iv) when comparing two rainfalls with same depths, the one with longer duration can saturate more the vegetated roof and thus undermine more its ability to retain water; and (v) when not managing the vegetation, the vegetated roof's soil moisture content loses correlation with the substrate depth, as plants will also develop more and will more effectively restore the substrate retention capacity. Conclusions point to extensive vegetated roofs as a relevant sustainable drainage system in subtropical areas, but demonstrate that its performance is highly dependent on structural factors, weather factors and level of maintenance. Such findings are expected to be useful for practitioners dimensioning these roofs as well as for policy makers towards a more accurate standardization of vegetated roofs in subtropical regions and Latin American developing countries.

The relationship between natural rain intensity and Ascochyta blight in chickpea development

Ascochyta blight management strategy in chickpea standing crops in Australia is solely based on applying protective fungicides before a forecast rainfall event. Despite this, studies on the likely interaction between natural rain (as well as simulated rain) amount, duration and Ascochyta blight development are rare. This study was conducted to investigate the relationship between natural rain intensity (mm/h) and Ascochyta blight development. Infested chickpea residue were placed at the soil surface, and three pots of a susceptible chickpea cultivar were randomly placed on each side of the plot (total 12 pots and 36 plants), preceding a forecast rainfall event. Trap plants were transferred to a controlled temperature room after rain events. After a 48 h incubation period, trap plants were transferred to a glasshouse to allow lesion development. The number of lesions on all plant parts were counted after two weeks. Lesions developed in rain amounts as low as 1.4 mm and rain durations as short as 0.7 h. The number of lesions significantly increased with increasing rain amount. There was a positive effect of increasing rain duration and a negative effect of increasing wind speed. This study suggests that small rain amounts, shorter duration rains or a limited amount of primary inoculum are not barriers to conidial dispersal or host infection, and that the current value of a rainfallthreshold (2 mm) for conidial spread and host infection is not accurate for susceptible cultivars.

Canopy Effects on Rainfall Partition and Throughfall Drop Size Distribution in a Tropical Dry Forest

The energy distribution of natural rainfall droplets at different stages of canopy development in low-latitude semi-arid environments is still understudied. We assessed relationships between canopy development, gross rainfall (P) and throughfall (TF) characteristics in a tropical dry forest (TDF) with a total of 95 events of natural rain during December 2019–July 2021, in Northeast Brazil. One disdrometer was installed in an open field to record the gross rainfall and another under the deciduous vegetation canopy to record the throughfall. At the onset of the rainy season with a low leaf density, a larger fraction of rainfall was converted into throughfall, which declines as the leaf density increases. For events higher than 3 mm, the number of TF drops was always higher than that of P and with smaller diameters, regardless of the stage of canopy development, which indicates fragmenting of the rain drops by the vegetation canopy. The insights of this study are useful to quantify the impact of canopy development stages of a TDF on the characteristics of rainfall reaching the soil forest. Since those characteristics affect the water balance and soil erosion at the hillslope scale, the information provided is crucial for water and soil management.

An Investigation on Super- and Sub-Terminal Drops in Two Different Rain Categories and Climate Regimes

The pressing need for accurate and reliable precipitation measurements and forecasting poses theoretical and technological problems. Remote-sensing instruments with increased coverage and sensitivity (such as space-borne and ground-based radar) are available; however, their full exploitation requires physical calibration and validation based on a deep knowledge of precipitation microphysics. This study reports a detailed analysis of the evidence of non-terminal velocities in a mid-latitude (Bologna, Italy) and a tropical location (Kolkata, India). The data from two identical disdrometers OTT-Parsivel2 were analyzed to shed light on the nature of the raindrops that fall at a velocity that is significantly higher (i.e., super-terminal drops) or lower (sub-terminal drops) than the terminal velocity expected for the raindrop sizes. The results show a significant fraction of super- and sub-terminal drops in both locations. The percentages of both super- and sub-terminal drops were higher in Kolkata. However, the difference was more notable for convective rain. The percentages of both super- and sub-terminal drops were found to be high within a drop diameter of 1 mm. The number of sub-terminal drops seemed to increase with an increase in diameter for drops larger than ~2.5 mm. The natural rain in Bologna showed stronger evidence of drop break-up in correspondence with the evolution of non-terminal velocities. Moreover, this study once again pointed toward the fact that the process of break-up cannot be neglected in natural rain of tropical or mid-latitude locations. We found that 7% and 10% of rain samples in Bologna and Kolkata seemed to be subjected to drop break-up. The results indicate that radar measurements of rain in the tropics or mid-latitude regions, relying on the Gunn–Kinzer relationship between velocity and diameter, should be verified by observations of disdrometers for a high precision QPE.

CEMENT COMPOSITES WITH WASTE INCORPORATION UNDER ACID RAIN ATTACK

The paper is aimed at the study of the resistance of cement pastes containing various secondary materials (fly ash, zeolite, zeoslag, slag and microsilica) in the model environment of acid rain. Changes in characteristics of the studied materials due to acid rain, such as compressive strength of cement composites, water absorption, penetration of aggressive ions, pH of material and its chemical composition were analysed. Model acidic environments represented solutions simulating acid rain with different pH values (2, 4 and 6). Natural acid rain, deionized water and saturated solution of Ca(OH)2 were used as reference media. Based on the experimental findings, it can be stated that a positive effect of the secondary materials on increasing the resistance of cement pastes has been proven. The cement pastes with added additives resulted in a significant reduction in permeability in each model environment. This fact has an impact on the overall durability due to the fact that the amount of aggressive ions in the internal structure is reduced, causing corrosion and subsequent deterioration of cement composites. Based on the innovative methodology for the ion-penetraton test of cement pastes, a coefficient was designed, which characterizes the effect of the used admixture in terms of pozzolanic resp. latent hydraulic activities. Based on this coefficient, the most significant positive effect was manifested by the use of an admixture of ash and zeolite. The rapid chloride penetration (RCP) test method has thus proved to be much more relevant in comparison with, for example, water absorption.

Influence of dust deposition, wind and rain on photovoltaic panels efficiency in Arequipa – Peru

ABSTRACT The present study the influence of dust, wind and rain on the performance of a photovoltaic was evaluated. To determine efficiency of panels influenced by external factors, a system was designed and installed, voltage, electric current, solar irradiance and temperatures were measured. Three types of dust were used to simulate the atmospheric dust; cement, ashlar and clay. Parameter considered for deposition of the powders was surface density (g/m2). Particle size was determined by granulometry, samples were analyzed by SEM/EDS. For the wind factor, three speeds were determined within a range of average speeds recorded in urban areas, tests were carried out in natural rain conditions. Results show that 06:00 a.m. to 5:30 p.m. energy generation efficiency of panels decreases due to increase of dust deposition. As well, it is shown that influence of wind increases efficiency slightly and that the performance of panels is directly influenced in rainy conditions.

Rain Forest Fragmentation and Environmental Dynamics on Nosy Be Island (NW Madagascar) at 1300 cal BP Is Attributable to Intensified Human Impact

Madagascar houses one of the Earth’s biologically richest, but also one of most endangered, terrestrial ecoregions. Although it is obvious that humans substantially altered the natural ecosystems during the past decades, the timing of arrival of early inhabitants on Madagascar as well as their environmental impact is still intensively debated. This research aims to study the beginning of early human impact on Malagasy natural ecosystems, specifically on Nosy Be island (NW Madagascar) by targeting the sedimentary archive of Lake Amparihibe, an ancient volcanic crater. Based on pollen, fungal spore, other non-pollen palynomorph, charcoal particle and diatom analyses combined with high-resolution sediment-physical and (in)organic geochemical data, paleoenvironmental dynamics during the past three millennia were reconstructed. Results indicate a major environmental change at ca. 1300 cal BP characterized by an abrupt development of grass (C4) dominated and fire disturbed landscape showing the alteration of natural rain forest. Further, increased soil erodibility is suggested by distinct increase in sediment accumulation rates, a strong pulse of nutrient input, higher water turbidity and contemporaneous increase in spores of mycorrhizal fungi. These parameters are interpreted to show a strong early anthropogenic transformation of the landscape from rain forest to open grassland. After ca. 1000 cal BP, fires remain frequent and vegetation is dominated by forest/grassland mosaic. While natural vegetation should be dominated by rain forest on Nosy Be, these last results indicate that human continuously impacted the landscapes surrounding the lake. At a local scale, our data support the “subsistence shift hypothesis” which proposed that population expansion with development of herding/farming altered the natural ecosystems. However, a precise regional synthesis is challenging, since high-resolution multi-proxy records from continuous sedimentary archives as well as records located further north and in the hinterland are still scarce in Madagascar. The lack of such regional synthesis also prevents precise comparison between different regions in Madagascar to detect potential (dis)similarities in climate dynamics, ecosystem responses and anthropogenic influences at the island’s scale during the (late) Holocene.