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.

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

2017 ◽  
Author(s):  
Milad Aminzadeh ◽  
Peter Lehmann ◽  
Dani Or
Keyword(s):  
Energy Balance ◽  
Water Body ◽  
Water Storage ◽  
Heat Fluxes ◽  
Radiative Properties ◽  
Radiative Energy ◽  
Wave Radiation ◽  
Water Reservoirs ◽  
Local Conditions ◽  
Self Assembling

Abstract. The growing pressure on natural fresh water resources and projected climate variability would expand the need for water storage during rainy periods. Evaporative losses present a challenge to efficient water storage reservoirs, especially in arid regions with chronic water shortages. Among the various methods for suppressing evaporative losses, the use of self-assembling floating elements offers a simple and scalable solution especially for small reservoirs. The use of floating elements is not new, yet the science behind the design and the resulting performance including other effects on the water body remain empirical. We propose a systematic approach for modeling the energy balance and fluxes from covered water surfaces considering element geometry, radiative properties and local conditions. The water energy balance equation was linked to the energy balance of floating discs on the surface of reservoir to consider the effect of surface coverage and cover properties on radiative energy storage within the water body and surface heat fluxes. The modeling results demonstrated significant drop in evaporative losses from covered reservoirs where incoming radiative flux is primarily intercepted by the cover surface and released into the atmosphere in form of long wave radiation and sensible heat fluxes yielding much higher Bowen ratio over covered relative to uncovered water reservoirs. The theoretical approach provides a scientific basis for an important water resource protection strategy and a predictive framework for design purposes.

scholarly journals Lake and wetland ecosystem services measuring water storage and local climate regulation

2017 ◽  
Vol 53 (4) ◽  
pp. 3197-3223 ◽  
Author(s):  
Christina P. Wong ◽  
Bo Jiang ◽  
Theodore J. Bohn ◽  
Kai N. Lee ◽  
Dennis P. Lettenmaier ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Water Storage ◽  
Wetland Ecosystem ◽  
Local Climate ◽  
Climate Regulation

A TEST OF THE RADIATIVE ENERGY BALANCE OF THE SHAW MODEL FOR SNOWCOVER

1996 ◽  
Vol 10 (10) ◽  
pp. 1359-1367 ◽  
Author(s):  
G. N. FLERCHINGER ◽  
J. M. BAKER ◽  
E. J. A. SPAANS
Keyword(s):  
Energy Balance ◽  
Radiative Energy

scholarly journals Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

2012 ◽  
Vol 16 (7) ◽  
pp. 1817-1831 ◽  
Author(s):  
F. Alkhaier ◽  
G. N. Flerchinger ◽  
Z. Su
Keyword(s):  
Energy Balance ◽  
Surface Temperature ◽  
Land Surface ◽  
Shallow Groundwater ◽  
Bare Soil ◽  
Heat Fluxes ◽  
Shortwave Radiation ◽  
Soil Conditions ◽  
Potential Evaporation ◽  
Available Energy

Abstract. Understanding when and how groundwater affects surface temperature and energy fluxes is significant for utilizing remote sensing in groundwater studies and for integrating aquifers within land surface models. To investigate the shallow groundwater effect under bare soil conditions, we numerically exposed two soil profiles to identical metrological forcing. One of the profiles had shallow groundwater. The different responses that the two profiles manifested were inspected regarding soil moisture, temperature and energy balance at the land surface. The findings showed that the two profiles differed in three aspects: the absorbed and emitted amounts of energy, the portioning out of the available energy and the heat fluency in the soil. We concluded that due to their lower albedo, shallow groundwater areas reflect less shortwave radiation and consequently get a higher magnitude of net radiation. When potential evaporation demand is sufficiently high, a large portion of the energy received by these areas is consumed for evaporation. This increases the latent heat flux and reduces the energy that could have heated the soil. Consequently, lower magnitudes of both sensible and ground heat fluxes are caused to occur. The higher soil thermal conductivity in shallow groundwater areas facilitates heat transfer between the top soil and the subsurface, i.e. soil subsurface is more thermally connected to the atmosphere. For the reliability of remote sensors in detecting shallow groundwater effect, it was concluded that this effect can be sufficiently clear to be detected if at least one of the following conditions occurs: high potential evaporation and high contrast between day and night temperatures. Under these conditions, most day and night hours are suitable for shallow groundwater depth detection.

Urban water storage capacity inferred from observed evapotranspiration recession 

2021 ◽  
Author(s):  
Harro Jongen ◽  
Gert-Jan Steeneveld ◽  
Jason Beringer ◽  
Krzysztof Fortuniak ◽  
Jinkyu Hong ◽  
...  
Keyword(s):  
Storage Capacity ◽  
Water Storage ◽  
Urban Water ◽  
Natural Forests ◽  
Local Climate ◽  
Water Storage Capacity ◽  
Vegetation Fraction ◽  
Local Climate Zones ◽  
Order Of Magnitude ◽  
Neighborhood Scale

<p>The amount and dynamics of urban water storage play an important role in mitigating urban flooding and heat. Assessment of the capacity of cities to store water remains challenging due to the extreme heterogeneity of the urban surface. Evapotranspiration (ET) recession after rainfall events during the period without precipitation, over which the amount of stored water gradually decreases, can provide insight on the water storage capacity of urban surfaces. Assuming ET is the only outgoing flux, the water storage capacity can be estimated based on the timescale and intercept of its recession. In this paper, we test the proposed approach to estimate the water storage capacity at neighborhood scale with latent heat flux data collected by eddy covariance flux towers in eleven contrasting urban sites with different local climate zones, vegetation cover and characteristics and background climates (Amsterdam, Arnhem, Basel, Berlin, Helsinki, Łódź, Melbourne, Mexico City, Seoul, Singapore, Vancouver). Water storage capacities ranging between 1 and 12 mm were found. These values correspond to e-folding timescales lasting from 2 to 10 days, which translate to half-lives of 1.5 to 7 days. We find ET at the start of a drydown to be positively related to vegetation fraction, and long timescales and large storage capacities to be associated with higher vegetation fractions. According to our results, urban water storage capacity is at least one order of magnitude smaller than the known water storage capacity in natural forests and grassland.</p>

scholarly journals Energy balance closure on a winter wheat stand: comparing the eddy covariance technique with the soil water balance method

2016 ◽  
Vol 13 (1) ◽  
pp. 63-75 ◽  
Author(s):  
K. Imukova ◽  
J. Ingwersen ◽  
M. Hevart ◽  
T. Streck
Keyword(s):  
Energy Balance ◽  
Water Balance ◽  
Winter Wheat ◽  
Water Content ◽  
Soil Water ◽  
Water Storage ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
Water Balance Method ◽  
Closure Method

Abstract. The energy balance of eddy covariance (EC) flux data is typically not closed. The nature of the gap is usually not known, which hampers using EC data to parameterize and test models. In the present study we cross-checked the evapotranspiration data obtained with the EC method (ETEC) against ET rates measured with the soil water balance method (ETWB) at winter wheat stands in southwest Germany. During the growing seasons 2012 and 2013, we continuously measured, in a half-hourly resolution, latent heat (LE) and sensible (H) heat fluxes using the EC technique. Measured fluxes were adjusted with either the Bowen-ratio (BR), H or LE post-closure method. ETWB was estimated based on rainfall, seepage and soil water storage measurements. The soil water storage term was determined at sixteen locations within the footprint of an EC station, by measuring the soil water content down to a soil depth of 1.5 m. In the second year, the volumetric soil water content was additionally continuously measured in 15 min resolution in 10 cm intervals down to 90 cm depth with sixteen capacitance soil moisture sensors. During the 2012 growing season, the H post-closed LE flux data (ETEC =  3.4 ± 0.6 mm day−1) corresponded closest with the result of the WB method (3.3 ± 0.3 mm day−1). ETEC adjusted by the BR (4.1 ± 0.6 mm day−1) or LE (4.9 ± 0.9 mm day−1) post-closure method were higher than the ETWB by 24 and 48 %, respectively. In 2013, ETWB was in best agreement with ETEC adjusted with the H post-closure method during the periods with low amount of rain and seepage. During these periods the BR and LE post-closure methods overestimated ET by about 46 and 70 %, respectively. During a period with high and frequent rainfalls, ETWB was in-between ETEC adjusted by H and BR post-closure methods. We conclude that, at most observation periods on our site, LE is not a major component of the energy balance gap. Our results indicate that the energy balance gap is made up by other energy fluxes and unconsidered or biased energy storage terms.

scholarly journals Energy balance measurements over a banana orchard in the Semiarid region in the Northeast of Brazil

2009 ◽  
Vol 44 (11) ◽  
pp. 1365-1373 ◽  
Author(s):  
Carlos Antonio Costa dos Santos ◽  
Bernardo Barbosa da Silva ◽  
Tantravahi Venkata Ramana Rao ◽  
Christopher Michael Usher Neale
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Eddy Covariance ◽  
Heat Fluxes ◽  
Irrigation District ◽  
Semiarid Region ◽  
Energy Balance Closure ◽  
Wet Season ◽  
Growing Seasons ◽  
Eddy Covariance System

The objective of this work was to evaluate the reliability of eddy covariance measurements, analyzing the energy balance components, evapotranspiration and energy balance closure in dry and wet growing seasons, in a banana orchard. The experiment was carried out at a farm located within the irrigation district of Quixeré, in the Lower Jaguaribe basin, in Ceará state, Brazil. An eddy covariance system was used to measure the turbulent flux. An automatic weather station was installed in a grass field to obtain the reference evapotranspiration (ET0) from the combined FAO-Penman-Monteith method. Wind speed and vapor pressure deficit are the most important variables on the evaporative process in both growing seasons. In the dry season, the heat fluxes have a similar order of magnitude, and during the wet season the latent heat flux is the largest. The eddy covariance system had acceptable reliability in measuring heat flux, with actual evapotranspiration results comparing well with those obtained by using the water balance method. The energy balance closure had good results for the study area, with mean values of 0.93 and 0.86 for the dry and wet growing seasons respectively.

scholarly journals Evaluation of Red Raspberry Cultivars Used for Breeding and Commercial Growing in the Baltic Region

2017 ◽  
Vol 71 (3) ◽  
pp. 203-210 ◽  
Author(s):  
Gunārs Lācis ◽  
Irita Kota-Dombrovska ◽  
Sarmīte Strautiņa
Keyword(s):  
Genetic Resources ◽  
Genetic Material ◽  
Climatic Conditions ◽  
Parent Material ◽  
Local Climate ◽  
Political Situation ◽  
Baltic Countries ◽  
Breeding Programmes ◽  
The Baltic ◽  
Local Advanced

Abstract The structure of raspberry cultivars and genetic resources in the Baltic countries have been influenced by the historical political situation in the 20th century and climatic conditions, especially winterhardiness. The genetic resources consist of some old European and American cultivars, but mostly of cultivars and hybrids bred in Russia. Currently, targeted breeding programmes are active only in Estonia and Latvia, which aim to develop winterhardy, disease-resistant cultivars, well adapted to the local climate. Therefore, parent material for hybridisation has been chosen from local advanced hybrids and introduced cultivars suitable to the regional climatic conditions. The aim of the study was to estimate the level of genetic diversity of Rubus germplasm and assess inter-specific and intra-specific relationships using phenotypical characterisation and molecular markers. Forty one Rubus genotypes were evaluated by 41 phenotypical traits and 15 previously described SSR markers. Both characterisation approaches discovered high correspondence with pedigree and a low level of diversity. A limited amount of the diversity of raspberry genetic material has been used in various breeding programmes, despite their broad geographical origin. The obtained results indicate the need for including local wild R. idaeus plant material into breeding programmes.

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