The influence of floating spheres on evaporation suppression under different climatic conditions

2021 ◽  
Author(s):  
Maram M. Shalaby ◽  
Ibrahim N. Nassar ◽  
Ahmed M. Abdallah
Keyword(s):  
Water Surface ◽  
Rainfall Variability ◽  
Aquatic Organisms ◽  
Climatic Conditions ◽  
Management Tool ◽  
Control Treatment ◽  
Suppression Efficiency ◽  
Evaporation Suppression ◽  
Water Ecology ◽  
Microalgae Growth

<p>Global warming and population growth increase the need for better management of freshwater resources, in particular in arid and semi-arid regions. Due to increased rainfall variability,  reservoirs became a vital management tool that stores the water during rainfall, thus decrease flood risks and supply water during drought periods. However, large amounts of water are lost by evaporation, which markedly affects reservoirs’ function of ensuring water availability. In Egypt, about 20.0% of the country's Nile share (12.1 to 15.4 billion m<sup>3</sup>) are lost annually by evaporation from Lake Nasser. The floating covers, i.e. spheres, shade the water surface and act as a physical barrier that decreases energy flux into the water, thus decrease evaporation. Studies that compare the evaporation suppression efficiency of the floating covers, over different climatic conditions, while considering its impact on the water ecology are limited.</p><p>A field experiment in an outdoor setting (class A-pan) was conducted for nine months (March to November) in two locations that vary in their climatic conditions, i.e. Aswan and Damanhur, representing northern and southern Egypt, respectively. The water surface was covered by white, black, or multicolor spheres, in addition to the control. Daily evaporation rate (ER), water temperature (WT), evaporation suppression efficiency (ESE), were determined. Moreover, the microalgae growth was measured as an indicator of water ecology.  </p><p>Obtained results revealed massive evaporation losses from the uncovered water surface (control) in Aswan location, in which the nine-month average was 2.25 times higher than in Damanhour location. The floating spheres reduced ER in both locations, in particular the white spheres. The ESE in Aswan was less than in Damanhour location. The ESE in Damanhour was 63.38, 58.13, and 54.8%, while in Aswan was 48., 42.5, and 41.6% for white, multicolor and black spheres, respectively. Floating spheres decreased WT in the morning and mid-day, while in the evening the control treatment was the coldest, indicating partial isolation of covered water surface. Irrespective of the spheres’ color, the spheres had no detrimental effect on microalgae growth, indicating enough light penetration and gas exchange through the gaps between spheres.</p><p>In conclusion, the floating spheres is an effective mean for evaporation suppression and its efficiency is dependent on the climate and spheres’ color. The ESE of spheres is lower in environments with lower relative humidity. The white spheres are recommended for evaporation suppression without negative impacts on microalgae growth which could be a viable indicator for the ecology of the water ecosystem. Further studies on larger water reservoirs are needed while considering several aquatic organisms.</p>

On the Use of Monolayers to Reduce Evaporation From Stationary Water Pools

1993 ◽  
Vol 115 (1) ◽  
pp. 209-214 ◽  
Author(s):  
T. D. Tang ◽  
M. T. Pauken ◽  
S. M. Jeter ◽  
S. I. Abdel-Khalik
Keyword(s):  
Experimental Investigation ◽  
Relative Humidity ◽  
Water Surface ◽  
Surface Film ◽  
Free Water ◽  
Vapor Concentration ◽  
Controlled Environment ◽  
Stearyl Alcohol ◽  
Water Pool ◽  
Evaporation Suppression

An experimental investigation has been conducted to quantify the extent by which monolayers of fatty alcohols can reduce evaporation from a deep stationary water pool within a controlled environment. Octadecanol (stearyl alcohol), C17H35–CH2–OH, was chosen as the surface film and ethanol was selected to be the spreading agent. Evaporation suppression of 60 percent was achieved at a water temperature of 25°C with an air temperature of 20°C and a relative humidity of 70 percent. The experimental techniques and data have been validated by comparing the measured evaporation rates for film-free water with earlier data published by other investigators. Data for the evaporation rates of water covered by octadecanol films were correlated as a function of vapor concentration differences between the water surface and air.

scholarly journals Variabilidade Espacial da Erosividade das Chuvas para o Estado da Paraíba (Variability of Spatial Erosivity of Rainfall in the Paraíba State)

2014 ◽  
Vol 7 (4) ◽  
pp. 691
Author(s):  
Bernardo Starling Dorta do Amaral ◽  
João Filadelfo de Carvalho Neto ◽  
Richarde Marques da Silva ◽  
José Carlos Dantas
Keyword(s):  
Water Resources ◽  
Rainfall Variability ◽  
Climatic Conditions ◽  
Climate Data ◽  
Rainfall Characteristics ◽  
R Factor ◽  
Erosivity Index ◽  
The Mean ◽  
Weather Stations ◽  
Soil Loss Equation

As características específicas das chuvas variam entre regiões, e o conhecimento da sua potencialidade erosiva é necessário para o planejamento dos recursos hídricos. Este estudo determinou a erosividade, analisou a variabilidade espacial da precipitação e o coeficiente de chuva para o Estado da Paraíba mediante técnicas de Sistemas de Informação Geográfica. Para a realização deste estudo foram utilizados dados climatológicos de 98 estações climatológicas da Embrapa, com séries de 1911 a 1990. Em seguida as informações sobre a erosividade foram processadas cartograficamente. O valor médio anual da erosividade das chuvas com base no índice EI30 para o Estado da Paraíba foi de 5.032,03 MJ.mm/ha/h, valor que representa o Fator “R” da Equação Universal de Perdas de Solo (USLE). As equações de regressão entre erosividade e precipitação e coeficiente de chuva não foram significativas. As principais conclusões são que: (a) os índices de erosividade encontrados são maiores na zona litorânea do que nas demais porções do Estado, e (b) as erosividades encontradas variaram de acordo com os valores da precipitação.   A B S T R A C T Specific rainfall characteristics vary among regions and their erosion potential must be known for the planning of water resources. This study analyzed the erosivity and rainfall variability and precipitation coefficient for Paraíba State based on Geographic Information Systems techniques. In order In this paper 98 climatological stations of Embrapa were used, with rainfall data of 1911 to 1990. For this study we use d climate data from 98 weather stations of Embrapa, with series from 1911 to 1990. Additionally we processed the information of the erosivity index cartographically by year and microregions. The mean annual value of erosivity was 5,032.03 MJ.mm/ha/h, which is to be used as “R” Factor in the Universal Soil Loss Equation (USLE) for Paraíba State and surrounding regions with similar climatic conditions. The main conclusions are that: (a) erosivity indexes are higher in coastal areas than in inland areas, and (b) the erosivity range according to the precipitation.   Keywords: erosivity, rainfall, water resources   

scholarly journals Evaporation suppression and energy balance of water reservoirs covered with self-assembling floating elements

2018 ◽  
Vol 22 (7) ◽  
pp. 4015-4032 ◽  
Author(s):  
Milad Aminzadeh ◽  
Peter Lehmann ◽  
Dani Or
Keyword(s):  
Energy Balance ◽  
Water Storage ◽  
Climatic Conditions ◽  
Heat Fluxes ◽  
Conservation Strategy ◽  
Radiative Energy ◽  
Water Reservoirs ◽  
Local Climate ◽  
Self Assembling ◽  
Evaporation Suppression

Abstract. The growing pressure on natural freshwater resources and the projected climate variability are expected to increase the need for water storage during rainy periods. Evaporative losses present a challenge for the efficiency of water storage in reservoirs, especially in arid regions with chronic water shortages. Among the available methods for suppressing evaporative losses, self-assembling floating elements offer a simple and scalable solution, especially for small reservoirs. The use of floating elements has often been empirically based; we thus seek a framework for systematic consideration of floating element properties, local climate and reservoir conditions to better predict evaporative loss, energy balance and heat fluxes from covered water reservoirs. We linked the energy balance of the water column with energy considerations of the floating elements. Results suggest significant suppression of evaporative losses from covered reservoirs in which incoming radiative energy is partitioned to sensible and long wave fluxes that reduce latent heat flux and thus increase the Bowen ratio over covered water reservoirs. Model findings were consistent with laboratory-scale observations using an uncovered and covered small basin. The study offers a physically based framework for testing design scenarios in terms of evaporation suppression efficiency for various climatic conditions; it hence strengthens the science in the basis of this important water resource conservation strategy.

SMALLHOLDER FARMER’S LIVELIHOOD DIVERSIFICATION AS A RESPONSE TO CHANGED CLIMATIC PATTERNS IN CHONGWE DISTRICT, ZAMBIA.

2020 ◽  
Vol 3 (1) ◽  
pp. 1-17
Author(s):  
Mbewe Jacqueline ◽  
Kabwe Harnadih Mubanga
Keyword(s):  
Climate Change ◽  
Smallholder Farmers ◽  
Rainfall Variability ◽  
Climatic Conditions ◽  
Theory And Practice ◽  
Farm Income ◽  
Significant Difference ◽  
Rainfall Patterns ◽  
On Farm ◽  
Impacts Of Climate Change

Purpose: Climate change affects local and global rainfall patterns and hence has a counter effect on smallholder agriculture. Impacts of climate change on agriculture are largely due to rainfall variability resulting in reduced yields due to crop-water stress and emergency of pathogens and diseases. In Zambia, climate change has been manifested through increased intensity of droughts and floods. These rainfall anomalies adversely affect agriculture and food systems. In order to survive the impacts of climate change and variability, smallholder farmers in Chongwe have adopted their livelihoods and farming systems to the new climatic patterns.Methodology: This study assessed how smallholder farmers in Chongwe District have adopted their livelihoods as a response to changed climatic conditions. It also investigated the perceptions of smallholder farmers as regards changes in aspects of their climatic conditions. Data collection involved a critical review of literature related to climate change and agriculture, observations, semi- structured interviews with 60 smallholder farmers and eight key informants. The data were analysed using multiple analysis techniques which included the descriptive statistics, One-way analysis of Variance (ANOVA), and the post-hoc Least Square Difference for pairwise comparisons of incomes from different livelihoods engaged in by smallholder farmers .The gendered comparisons of livelihood engagement was done using the chi-square test of association.Findings: The results showed that all farmers perceived occurrence of changes in climatic conditions in the light of changed rainfall patterns in that there has been uncertainty in onset of rains, short rainy season, more intermittent rainfall and increased frequency of intra-seasonal droughts. These changes have led to farmers to adopt such farming techniques as potholing in preference to oxen and tractor ploughing when farming is done on smaller pieces of land. There was a significant difference in the mean annual incomes generated from on-farm livelihoods (ZMW 3677.59; n=58) and off-farm livelihoods (ZMW 6840.91; n = 58) (p= 0.001). Farmers generated the highest income returns by engaging in casual work (ZMW 10307.69; n = 13) compared to every other livelihoods common in the area such as gardening (p=0.002), petty trade (p=0.002) and on-farm livelihoods (p=0.001).Contribution to policy, theory and practice: It was therefore concluded that diversification of income through diversified livelihoods would help smallholder farmers enhance their resilience in the face of changed climatic conditions. On-farm livelihoods should not always be the main income source for farmers as results indicated that farmers engaged in casual work generated higher incomes than those who depended on farming. It was recommended that policy direction should be towards introduction of a gender responsive credit facility that can help improve women’s engagement in off-farm income generating livelihoods, as well as encourage climate change resilience.

Seed-bank and seedling dynamics in Hyparrhenia hirta are influenced by herbicide application and mowing management

2012 ◽  
Vol 34 (2) ◽  
pp. 199 ◽  
Author(s):  
V. K. Chejara ◽  
P. Kristiansen ◽  
B. M. Sindel ◽  
R. D. B. Whalley ◽  
C. Nadolny
Keyword(s):  
Seed Bank ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Climatic Conditions ◽  
Control Treatment ◽  
Native Flora ◽  
Seedling Dynamics ◽  
Herbicide Treatments ◽  
Seedling Emergence And Survival

Hyparrhenia hirta (L.) Stapf (Coolatai grass) is a summer-active, C4 perennial tussock grass, native to southern Africa and the Mediterranean region, which has invaded areas of native flora in Australia in recent decades. Understanding its seed and seedling dynamics and how various management treatments (e.g. mowing, herbicide and no management) affect these may assist in identifying the conditions and management strategies required to limit its invasion. The population dynamics of H. hirta have not been comprehensively studied previously. A 2-year field experiment (December 2005–December 2007) was conducted to determine the seed-bank size, pattern of seedling emergence and survival of H. hirta seedlings at three sites in northern New South Wales, Australia, under three treatments: unmanaged (control), mowing and herbicide treatments. The density of H. hirta seeds in the soil at each experimental site under different treatments was measured in December 2005 at the start of the experiment, in December 2006 before the application of the second round of treatments and again at the end of the experiment in December 2007. Hyparrhenia hirta seedlings were assessed at monthly intervals in permanent quadrats (0.5 × 0.5 m) to determine seedling emergence and survival. Seedling emergence occurred on many occasions during the 2-year period of the experiment in each treatment and at all sites but the main seedling flushes were observed from mid summer to early autumn. In 2007, at all sites, seedling emergence declined by more than 90% on the mowing and herbicide treatments compared with the control treatment. Seedling survival was greater in the mowing and herbicide treatments than in the control treatment. The seedling cohorts emerging in winter had a lower survival. This study showed that H. hirta infestations have a large viable seed-bank (~3000 m–2), dependent on the level of infestation and climatic conditions, but that the seed-bank declines rapidly when seed addition is prevented. Some form of direct control of established H. hirta plants in combination with providing appropriate grazing management to encourage competition between grasses will assist in the control of H. hirta.

Effects of a pharmaceutical mixture at environmentally relevant concentrations on the amphipod Gammarus fossarum

2010 ◽  
Vol 61 (2) ◽  
pp. 196 ◽  
Author(s):  
Sabine Dietrich ◽  
Shana Dammel ◽  
Florian Ploessl ◽  
Franz Bracher ◽  
Christian Laforsch
Keyword(s):  
Body Length ◽  
Aquatic Organisms ◽  
Freshwater Ecosystems ◽  
Control Treatment ◽  
High Concentration ◽  
Gammarus Fossarum ◽  
Drug Mixture ◽  
High Concentrations ◽  
Concentration Levels ◽  
Complex Drug

The continuous discharge of pharmaceuticals into the environment results in the chronic exposure of aquatic organisms to complex drug mixtures. We examined the influence of a mixture of pharmaceuticals (carbamazepine (CBZ), diclofenac (DIC), metoprolol (MET) and 17α-ethinylestradiol (EE2)) at environmentally relevant (‘env’) and artificially high (‘high’) concentrations on Gammarus fossarum. Different sublethal responses such as moulting, reproduction and the content of the energy-storage component glycogen were analysed. The drug mixture influenced the moulting behaviour of gammarids at both the ‘env’ and ‘high’ concentration levels, leading to a discontinuous increase of body length in successive moults, compared with the constant increase of body length in the control treatment. Moreover, the time between successive moults of animals exposed to the ‘env’ and ‘high’ pharmaceutical concentrations was decreased because of shortened intermoult periods. We observed no significant impact of the pharmaceuticals on reproduction. In addition, the content of glycogen was not significantly affected by the drug mixture. Permanent exposure of G. fossarum to a wider range of pharmaceuticals in natural aquatic systems may influence moulting behaviour and accompanied life-history parameters, followed by severe ecological consequences as gammarids play an important role in many freshwater ecosystems of the northern hemisphere.

scholarly journals Whole plant community transplants across climates reveal structural community stability due to large shifts in species assemblage

2018 ◽  
Author(s):  
Sara Tomiolo ◽  
Mark C. Bilton ◽  
Katja Tielbörger
Keyword(s):  
Climate Change ◽  
Plant Communities ◽  
Plant Density ◽  
Eastern Mediterranean ◽  
Rainfall Variability ◽  
Climatic Conditions ◽  
Community Response ◽  
Community Stability ◽  
Species Abundances ◽  
Mediterranean Regions

Summary(1) Climate change will decrease precipitation and increase rainfall variability in Eastern Mediterranean regions, with responses of plant communities largely uncertain. Here, we tested short-term responses of dryland plant communities to contrasting rainfall regimes using a novel experimental approach.(2) We exposed three annual plant communities to sharp changes in climatic conditions using whole community reciprocal transplants of soil and seed banks. We tested for the role of climate vs. community origin on community response and resistance. In parallel, we asked whether origin-specific climatic adaptations predict compositional shifts across climates.(3) For both community origins, the most dry-adapted species in each community increased in dry climate and the wet-adapted species increased in wet climate. Dry community origins showed large compositional shifts while maintaining stable plant density, biomass and species richness across climates. Conversely, wet communities showed smaller compositional shifts, but larger variation in biomass and richness.(4) Asynchrony in species abundances in response to rainfall variability could maintain structural community stability. This, in combination with seed dormancy, has the ability to delay extinction in response to climate change. However, increasing occurrence of extreme droughts may, in the long-term, lead to loss of wet-adapted species.

scholarly journals (128) Effect of 2,4-DP Concentration on Fruit Drop Control and Maturation of `Braeburn' Apples

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1062B-1062
Author(s):  
Patricia Garriz ◽  
Graciela Colavita ◽  
Hugo Alvarez ◽  
Valeria Blackhall
Keyword(s):  
Apple Fruit ◽  
Soluble Solids ◽  
Management Tool ◽  
Control Treatment ◽  
Starch Degradation ◽  
Potential Yield ◽  
Uniform Size ◽  
Fruit Abscission ◽  
Synthetic Auxin ◽  
Fruit Drop

Apple fruit abscission shortly before harvest is a frequent, recurring problem, thereby reducing potential yield. The synthetic auxin 2 (2,4-dichlorophenoxy) propionic acid (2,4-DP) was evaluated for its effect on reducing fruit drop and influencing ripening of `Braeburn' apples, in the High Valley region of Río Negro, Argentina (38°56'S, 67°59'W). Thirteen-year-old apple trees grafted on MM 111 rootstock were sprayed on 4 Mar. 2005, at 162 days after full bloom (DAFB) with 2,4-DP at doses of 0.05% and 0.10% (v/v), applied with an airblast sprayer, until runoff. Each tree was trained to palmette and planted in a single row from north to south with spacing of 2.3–4.0 m. The following measurements were performed: a) accumulated fruit drop, twice per week and b) maturity indices, weekly. Samples of uniform-size fruits were assessed for maturity (n = 20 per date and treatment), from 167 (commercial harvest) to 195 DAFB. On 23 Mar. (at 181 DAFB), cumulative fruit drop for control treatment was 19.9%, whereas 2,4-DP significantly reduced it to 4.90% and 2.94% at 0.05% and 0.10% (v/v), respectively. Reduction in the drop was also significant later, and 2,4-DP at both doses controlled drop comparably. The synthetic auxin did not affect fruit quality and maturation, based upon flesh firmness, starch degradation, and soluble solids concentration. We conclude that 2,4-DP is an effective drop control compound and it is useful as a management tool to increase yield by reducing fruit abscission and to extend the harvesting window of `Braeburn' apples, since it does not affect ripening. Delaying harvest may provide flexibility for scheduling of labor, fruit processing and packaging, cold storage, and marketing.

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