A Python-based GIS Simulation of the Spatial and Temporal Variation in Evapotranspiration

2019 ◽  
Vol 35 (5) ◽  
pp. 759-765 ◽  
Author(s):  
Mohammed G. Mohammed ◽  
Kathleen M. Trauth
Keyword(s):  
Overland Flow ◽  
Potential Evapotranspiration ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Water Losses ◽  
Python Script ◽  
Space And Time ◽  
Land Covers ◽  
A Site ◽  
Linn County

Abstract. An assessment of potential evapotranspiration (ET) and direct evaporation is important for informed land management from agriculture to wetlands restoration. These processes vary in space and time, depending on vegetation, soils, and climate throughout the year. Much data has been collected in order to quantify ET for individual plots of land, but means have not been available to provide an integrated view on a landscape scale. A methodology has been developed and an implementing Python script has been written to assess and display the spatial and temporal variability of ET and direct evaporation using a geographic information system (GIS). The methodology utilizes publicly available inputs for broad applicability, and the calculations can be performed for a site with multiple land covers and soil textures. In addition to a visual representation of ET and direct evaporation in space and time, the Python script produces a text file of water losses that could be used in water balance calculations also incorporating precipitation, overland flow and infiltration. The methodology has been demonstrated on a site within Pershing State Park in Linn County, Missouri, and produces results consistent with those expected from hand calculations. All data and code are available in GitHub (https://github.com/TrauthK/Wetlands). Keywords: Evapotranspiration, Evaporation, GIS simulation, Hydrologic modeling, Hydrologic cycle, Python, Raster data, Wetland restoration.

scholarly journals Trait evolution under multiple selection pressures: Prey responses to predictable and unpredictable variation

2019 ◽  
Author(s):  
Manvi Sharma ◽  
Kavita Isvaran
Keyword(s):  
Variable Selection ◽  
Predation Risk ◽  
Selection Pressure ◽  
Spatial And Temporal Variation ◽  
Rock Pools ◽  
Selection Pressures ◽  
Space And Time ◽  
Natural Settings ◽  
Oviposition Sites ◽  
Desiccation Risk

AbstractWhen a strong selection pressure, such as predation risk, varies widely in space and time, how should prey respond? When risk varies predictably, prey are hypothesized to respond in a risk-sensitive manner. It is less clear how prey should respond when risk varies unpredictably.Additionally, prey response may also depend on how predation risk interacts with other selection pressures. Our understanding of the complex action of multiple and variable selection pressures on prey traits is still comparatively poor. Here, we examine how predictable and unpredictable aspects of predation risk act together with another important selection pressure to influence prey behaviour in the rock pool breeding mosquito, Aedes vexans. Through the selection of sites for oviposition, female mosquitoes can influence the predation risk faced by their offspring. We tested how females select oviposition sites, when encountering pools that vary in larval predation risk and desiccation risk. We comprehensively quantified spatial and temporal variation in predation risk by measuring densities of predatory dragonfly nymphs in rock pools of different sizes, along the mosquito breeding season. We also measured hydroperiod length. We next conducted manipulative experiments in rock pools and measured female oviposition responses to variation in predation and desiccation risks. Predation risk varied widely in space and time. Desiccation risk only appeared important for the small pools. Ovipositing females appeared to respond to these multiple aspects of variation in selection pressures. Females seemed to respond to predictable variation by avoiding large pools that permanently harboured predators in natural settings. Female responses were more variable to medium-sized pools with naturally stochastic predator densities, highlighting the role of unpredictability in predation risk in shaping behaviour. Females did not clearly prefer small pools that were naturally devoid of predators but carried high desiccation risk, suggesting that they balance multiple risks – predation versus desiccation – when choosing oviposition sites. Our study suggests that wild populations may commonly experience multiple and variable selection pressures that can favour seemingly puzzling trait variation. We highlight the need to quantify variation in selection pressures and investigate how such variation, especially the unpredictable aspects, shapes prey traits.

scholarly journals Spatial and temporal variation of methane emissions in drained eutrophic peat agro-ecosystems: drainage ditches as emission hotspots

2008 ◽  
Vol 5 (2) ◽  
pp. 1237-1261 ◽  
Author(s):  
A. P. Schrier-Uijl ◽  
E. M. Veenendaal ◽  
P. A. Leffelaar ◽  
J. C. van Huissteden ◽  
F. Berendse
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Table ◽  
Soil Moisture Content ◽  
Explanatory Variable ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Ch4 Emissions ◽  
Intensively Managed ◽  
Moisture Conditions

Abstract. Our research investigates the spatial and temporal variability of methane (CH4) emissions in two drained eutrophic peat areas (one intensively managed and the other less intensively managed) and the correlation between CH4 emissions and soil temperature, air temperature, soil moisture content and water table. We stratified the landscape into landscape elements that represent different conditions in terms of topography and therefore differ in moisture conditions. There was great spatial variability in the fluxes in both areas; the ditches and ditch edges (together 27% of the landscape) were methane hotspots whereas the dry fields had the smallest fluxes. In the intensively managed site the fluxes were significantly higher by comparison with the less intensively managed site. In all the landscape element elements the best explanatory variable for CH4 emission was temperature. Neither soil moisture content nor water table correlated significantly with CH4 emissions, except in April, where soil moisture was the best explanatory variable.

A model for estimating soil moisture deficits under cereal crops in Britain:1. Development

1982 ◽  
Vol 98 (3) ◽  
pp. 651-661 ◽  
Author(s):  
P. E. Francis ◽  
J. D Pidgeon
Keyword(s):  
Potential Evapotranspiration ◽  
System Development ◽  
Free Water ◽  
Soil Surface ◽  
Cereal Crops ◽  
Water Losses ◽  
Crop Species ◽  
Detailed Model ◽  
Stage Of Development ◽  
Wide Range

SUMMARYA new and detailed model, involving meteorological, crop and soil variables, is proposed to provide daily estimates of moisture deficits in soils under cereal cropping in Britain. The model incorporates developments in the calculation of potential evapotranspiration specifically for cereal crops. Four processes of loss of water are considered, namely drainage, evaporation of free water from the crop canopy, evaporation from the soil surface and transpiration by the crop. Thus the model is applicable at all stages of the cropping cycle. Above-ground and root system development of the crop are modelled and available and extractable water capacities of a wide range of soils are estimated. Thus the demand for water and its availability are varied with crop species, stage of development and soil type as well as with meteorological variables.The calculation of water losses is not dependent on arbitrary assumptions about the division of losses between the four processes considered or between different horizons of the soil.Extreme simplicity of input data requirement has been maintained. The model has been programmed in FORTRAN, and is compatible with Meteorological Office data archives.

scholarly journals Methods for Exploring Spatial and Temporal Variability of Extreme Events in Climate Data

2008 ◽  
Vol 21 (10) ◽  
pp. 2072-2092 ◽  
Author(s):  
C. A. S. Coelho ◽  
C. A. T. Ferro ◽  
D. B. Stephenson ◽  
D. J. Steinskog
Keyword(s):  
Value Theory ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Spatial Dependency ◽  
Climate Data ◽  
Explanatory Factors ◽  
Generalized Pareto ◽  
Pareto Model ◽  
Grid Points ◽  
Extremal Properties

Abstract This study presents various statistical methods for exploring and summarizing spatial extremal properties in large gridpoint datasets. Extremal properties are inferred from the subset of gridpoint values that exceed sufficiently high, time-varying thresholds. A simple approach is presented for how to choose the thresholds so as to avoid sampling biases from nonstationary differential trends within the annual cycle. The excesses are summarized by estimating parameters of a flexible generalized Pareto model that can account for spatial and temporal variation in the excess distributions. The effect of potentially explanatory factors (e.g., ENSO) on the distribution of extremes can be easily investigated using this model. Smooth spatially pooled estimates are obtained by fitting the model over neighboring grid points while accounting for possible spatial variation across these points. Extreme value theory methods are also presented for how to investigate the temporal clustering and spatial dependency (teleconnections) of extremes. The methods are illustrated using Northern Hemisphere monthly mean gridded temperatures for June–August (JJA) summers from 1870 to 2005.

scholarly journals Biophysical Effects of Evapotranspiration on Steppe Areas: A Case Study in Naâma Region (Algeria)

2021 ◽  
Author(s):  
Abdelkrim Benaradj ◽  
Hafidha Boucherit ◽  
Abdelkader Bouderbala ◽  
Okkacha Hasnaoui
Keyword(s):  
Mediterranean Climate ◽  
Potential Evapotranspiration ◽  
Thick Layer ◽  
Soil Surface ◽  
Cold Season ◽  
Perennial Grasses ◽  
Herbaceous Plants ◽  
Humid Climate ◽  
Water Losses ◽  
Steppe Vegetation

The Algerian steppe is of great interest in terms of vegetation, mainly in the Naâma region. This steppe vegetation is generally composed of annual and perennial grasses and other herbaceous plants, as well as, bushes and small trees. It is characterized by an arid Mediterranean climate where the average annual precipitation (100 to 250 mm) is insufficient to ensure the maintenance of the vegetation, in which the potential evaporation always exceeds the precipitations. This aridity has strong hydrological effect and edaphic implications from which it is inseparable. Water losses are great than gains due to the evaporation and transpiration from plants (evapotranspiration). The wind moves soils for one location to another, and causes a strong evapotranspiration of the plants, which is explained by a strong chronic water deficit of climatic origin of these compared to the potential evapotranspiration, opposed to a humid climate. Evapotranspiration is certainly closely linked to climate factors (solar radiation, temperature, wind, etc.), but it also depends on the natural environment of the studied region. Potential evapotranspiration (PET) data estimated from Thornthwaite’s method for the three stations (Mécheria, Naâma and Ainsefra). The average annual value of potential evapotranspiration is of the order of 807 mm in Mécheria, of 795 mm in Naâma de and in Ainsefra of 847 mm. It is more than 3 times greater than the value of the rainfall received. This propels it globally in the aridity of the region and from which the water balance of plants is in deficit. The potential evapotranspiration of vegetation in arid areas is very important due to high temperature and sunshine. During the cold season, precipitation covers the needs of the potential evapotranspiration and allows the formation of the useful reserve from which the emergence of vegetation. From the month of April there is an exhaustion of the useful reserve which results of progressive deficit of vegetation. Faced with this phenomenon of evatranspiration, the steppe vegetation of the region then invests in “survival” by reducing the phenomena of evapotranspiration, photosynthetic leaf surfaces, in times of drought. These ecophysiological relationships can largely explain the adaptation of steppe species (low woody and herbaceous plants) to the arid Mediterranean climate. Mechanisms and diverse modalities were allowing them to effectively resist for this phenomenon. The adaptation of the steppe vegetation by the presence of a root system with vertical or horizontal growth or both and seems to depend on the environmental conditions, and by the reduction of the surface of transpiration, and by the fall or the rolling up of the leaves, and by a seasonal reduction of transpiration surface of the plant to reduce water losses during the dry season (more than 6 months) of the year.. Some xerophytes produce “rain roots” below the soil surface, following light precipitation or during dew formation. Other persistent sclerophyllous species by which decreases transpiration by the hardness of the leaves often coated with a thick layer of wax or cutin.

scholarly journals Spatial and Temporal Variation in an Apple Orchard

HortScience ◽  
2019 ◽  
Vol 54 (12) ◽  
pp. 2182-2187
Author(s):  
Babak Talebpour ◽  
Maksut Barış Eminoğlu ◽  
Uğur Yegül ◽  
Ufuk Türker
Keyword(s):  
Temporal Variation ◽  
Precision Agriculture ◽  
Temporal Stability ◽  
Apple Orchard ◽  
The Other ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Research Station ◽  
Temporal Variance ◽  
Over Time

One important goal of precision horticulture (PH), as well as precision agriculture (PA), is to measure and manage spatial and temporal variation in orchards. In this study, temporal and spatial analysis of yields were carried out over 2 years for a 0.5-ha apple orchard (at the Haymana Research Station of Ankara University, Turkey, from 2017 to 2018) to determine the variability of yields over time and included seven apple varieties: ‘Royal Gala’, ‘Red Chief’, ‘Braeburn’, ‘Mondial Gala’, ‘Jonagold’, ‘Fuji’, and ‘Mitch Gala’. To achieve this, yield data for two different years were analyzed for mean yield, temporal variance, and cv in terms of spatial and temporal stability, and their yield maps were produced. The results showed that ‘Jonagold’, ‘Braeburn’, and ‘Red Chief’ varieties yielded less than the average yield, whereas the other varieties produced average yields when the yield from 2 years was taken into account. Calculation of the values for determining temporal stability over time resulted in all existing varieties being identified as stable over time. For example, the ‘Jonagold’ and ‘Red Chief’ varieties showed 100% stability in terms of temporal variance. Results also showed that the ‘Gala’ varieties were stable for 2 years and produced high yields, whereas the other varieties were specified as stable and low yielding when spatial and temporal variability was considered in combination.

scholarly journals Phosphorus, nitrogen and sediment losses from irrigated cropland and pasture grazed by cattle and sheep

2008 ◽  
pp. 77-83 ◽  
Author(s):  
R.W. Mcdowell ◽  
D.J. Houlbrooke
Keyword(s):  
Overland Flow ◽  
Cattle Grazing ◽  
Silt Loam ◽  
Physical Damage ◽  
Forage Crops ◽  
Structural Degradation ◽  
N Losses ◽  
Crop Land ◽  
A Site ◽  
Cattle And Sheep

Grazing forage crops during winter can lead to soil physical damage and contaminant losses especially on Pallic soils prone to compaction and structural degradation. A site in North Otago (Timaru silt loam) with 2 years sheep and cattle grazing on winter forage crops and pasture was used to measure phosphorus (P) and nitrogen (N) losses in sub-surface (leachate from shallow lysimeters) flow and P losses in overland flow. Keywords: phosphorus, nitrogen, sediment, irrigation, overland flow, treading, grazing, pasture, crop land

scholarly journals Aplicability of sap flow data in hydrological modeling

2021 ◽  
pp. 54-65
Author(s):  
С.Ю. ЛУПАКОВ ◽  
Т.С. ГУБАРЕВА ◽  
В.В. ШАМОВ ◽  
А.В. РУБЦОВ ◽  
Б.И. ГАРЦМАН ◽  
...  
Keyword(s):  
Water Balance ◽  
Sap Flow ◽  
Hydrological Modeling ◽  
Hydrological Model ◽  
Potential Evapotranspiration ◽  
Flow Data ◽  
Water Losses ◽  
Flow Measurements ◽  
Small Catchment ◽  
Daily Evaporation

Статья содержит результаты моделирования стока малого речного бассейна в верховьях р. Уссури с использованием оригинальных данных о стволовом сокодвижении, пересчитанных в объем воды, транспирируемый древостоем. В теплый период 2019 г. на территории Верхнеуссурийского стационара ФНЦ биоразнообразия наземной биоты Восточной Азии ДВО РАН проведен комплекс наблюдений за компонентами влагооборота, позволивший накопить необходимый массив данных для гидрологического моделирования. В дополнение к традиционным водно-балансовым измерениям проводился мониторинг транспирации на основе системы датчиков регистрации водотока в стволах деревьев. Полученные данные точечных наблюдений распространены на масштаб водосбора (площадь около 3.1 км2). Показано, что в теплых и сухих условиях объем суточного суммарного испарения с малого речного бассейна может достигать 8.5 тыс. м3, что больше объема речного стока за тот же период в 5–6 раз, а во время выпадения дождей транспирация деревьев уменьшается практически до нуля. Для расчета водного баланса изучаемого объекта использована гидрологическая модель HBV (Hydrologiska Byråns Vattenbalansavdelning). Ряды суточной потенциальной эвапотранспирации, рассчитанные на основе широко используемых методов Пенмана-Монтейса и Одина, применены в HBV как входные данные. Расчетные суточные значения испарения, по сравнению с полученными на основе данных стволового сокодвижения, оказались выше в 1.5–2 раза, разница сумм испарения за весь теплый период года достигает слоя 100 мм и более. При этом надежной связи между расчетными значениями суточного испарения и измерениями не было обнаружено. Сделан вывод, что использование приборных данных о стволовом сокодвижении в составе входных переменных в гидрологическую модель повышает качество расчетов стока. The article deals with the experience of applying an alternative method for quantifying evapotranspiration volume as input to the hydrological model to simulate runoff of a small catchment located in the upper reaches of the Ussuri River. In the warm period of 2019 at the territory of the Verkhneussuriyskiy station of the Federal Scientific Center of the East Asia Terrestrial Biodiversity (FEB RAS), a set of field measurements was carried out. The measured data were used to calibrate the HBV hydrological model (Hydrologiska Byråns Vattenbalansavdelning). In addition to traditional water-balance measurements, there was assessed the evapotranspiration rate based on sap flow measurements eliminating other parts of water losses. The Tissue Heat Balance technique was applied to measure a sap flow in some individual trees. After that, the obtained data were scaled up to the catchment area (3.1 km2). It is shown that in warm and dry weather conditions, the volume of daily total evaporation from a small catchment can reach 8.5 ths.m3 that is 5-6 times more than the river runoff volume over the same period. During the rainfall events, the transpiration rate in trees decreases to almost zero. To compare the obtained results with the modelled ones, the potential evapotranspiration was also calculated based on well-known Penman-Monteith’s and L. Oudin’s methods that forced HBV model as input. Based on hydrological simulations, these methods overestimated the actual daily evaporation volume up to 2 times in comparison with the sap flow data, and the difference for the warm season reaches 100 mm and more. No reliable relationship was found between the calculated values of daily evaporation rate and the conventionally “measured” ones. Basically, runoff simulations quality was improved while using evapotranspiration volume assessed with the sap flow data. We conclude that water balance via HBV simulations is quite different depending on applied evapotranspiration method. In this case, overestimated volume of evapotranspiration by Penman-Monteith and L. Oudin methods leads to excessive water extraction from the HBV soil moisture storage. If it’s actually not correct, long-term runoff simulations would result in wrong water balance and error accumulation.

scholarly journals Patterns of Temporal and Spatial Variability of Sponge Assemblages

2021 ◽  
Author(s):  
◽  
Jade Berman
Keyword(s):  
New Zealand ◽  
Environmental Conditions ◽  
South Coast ◽  
Spatial And Temporal Variability ◽  
Taxonomic Distinctness ◽  
Monitoring Methods ◽  
Data Set ◽  
Significant Group ◽  
Temporal Factors ◽  
A Site

<p>The primary goals of this thesis were to understand the spatial and temporal pattern of sponge assemblage variation over a variety of scales and investigate suitable monitoring methods for sponge assemblages. Sponges are an ecologically significant group in benthic marine communities, which are often ignored in current monitoring schemes. In chapter two the sponge biodiversity of New Zealand waters to 200m was examined using Taxonomic Distinctness measures initially to test if genera data could be used as a proxy for species level data in New Zealand waters. It was found that over 50% of the variation in genera biodiversity could be explained by location and depth around New Zealand. The study helped pinpoint where there were gaps in the New Zealand dataset, in particular for the West Coast of the South Island and also areas such as the Wellington South Coast, which had higher than expected values for Average and Variation Taxonomic distinctness measures, which as important areas where sponges should be monitored to make sure the high levels of biodiversity are protected. Taxonomic distinctness measures are useful for initially assessing how the biodiversity is distributed, especially when using a data set with uneven sampling effort, as it is robust to spatial and temporal bias in the majority of cases. However, there was an outlier to the genera data correlating well with the variation in species data in the case of a site dominated by Haliclona sp (Lyttelton Harbour). In chapters three and four the spatial and temporal variability of sponge assemblages of the Wellington South Coast were explored creating both a species list for the area and an understanding of how the sponge assemblage varies over time and space. There were significant differences in the sponges assemblages in similar habitat types over a scale of a few hundred metres. In addition, although all the sponge assemblages changed seasonally, the changes at each sampling site responded in a slightly different way most likely due to spatiotemporal variation in environmental conditions. A similar seasonal pattern was also observed in chapter five for sponge assemblages at Skomer Marine Reserve and this pattern was also clear when using morphological monitoring methods. This means that once a site has been mapped for biodiversity it is possible for some habitats to use morphological monitoring to identify if the sponge assemblage is changing significantly saving time and money. The results from Indonesia (chapter six) showed that although the sponge assemblages were changing significantly in the actual species present and their abundances, the proportion of diversity within each spatial level (quadrat, site and region) remained consistent when sampled at the same time each year throughout the five year study. In species rich assemblages there are a variety of life strategies that can respond differently to shifts in environmental conditions and contribute to ecological functioning in various ways. Various monitoring methods have been tested using sponge assemblages over various spatial and temporal scales in this thesis. Spatial, temporal and the interaction of spatial and temporal factors were all important for identifying significant assemblage differences at all of the sites. Further studies integrating the interaction of spatial and temporal factors into understanding monitoring data sets are vital to understand the patterns of assemblage variability and therefore incorporate into habitat management plans.</p>

scholarly journals Spatial and Temporal Variation of Fish Assemblages in Seti Gandaki River, Tanahu, Nepal

2020 ◽  
Vol 10 (2) ◽  
pp. 93-104
Author(s):  
ARCHANA PRASAD ◽  
ANJANA SHRESTHA ◽  
JASH HANG LIMBU ◽  
DEEP SWAR
Keyword(s):  
Community Structure ◽  
Fish Community ◽  
Fish Assemblages ◽  
Mesh Size ◽  
Spatial And Temporal Variation ◽  
Total Hardness ◽  
Medium Size ◽  
Fish Community Structure ◽  
Space And Time ◽  
Significant Difference

The space and time variations of the fish community structure in hill streams of Nepal are poorly understood. This research aims at studying the space and time variation of fish community structure in the Seti Gandaki River, Tanahu, Nepal. The field survey was conducted from July 2017 to June 2018 and the fishes were sampled from six sites using a medium size cast net of mesh size ranging from 3 mm to 6 mm mesh size, 25-33 feet length and 3.5-5 feet width, with the help of local fisher man. A total of 1,440 individuals were caught representing 46 species belonging to three order, nine families and 23 genera. The analysis of similarity (ANOSIM) showed significant difference in space (R = 0.824, P = 0.001) but not in time (R = 0.135, P = 0.021). On the basis of similarity percentage (SIMPER) analysis, 85.43% similarity was found among the seasons and major contributing species were Barilius bendelisis (8.44%) followed by B. vagra (7.79%), Tor putitora (7.27%), Garra gotyla (7%), Acanthocobotis botia (6.7%), Neolissochilus hexagonolepis (6.64%), Barilius shacra (6%), B. barila (4.5%) and Opsarius barna (4.37%). On the other hand, 85.24% similarity was found among the sites and major contributing species were B. bendelisis (8.8%) followed by B. vagra (7.6%), G. gotyla (7.27%), T. putitora (7.17%), A. botia (6.97%), N. hexagonolepis (6.7%), B. shacra (6.34%), B. barila (4.7%) and O. barna (4.39%). Results from the Canonical Correspondence Analysis indicated that the environmental variables, such as pH, total hardness, alkalinity, dissolved oxygen and water temperature have shown to determine the fish community structure of Seti Gandaki River. Keywords: Fish diversity, freshwater, habitat, spatio-temporal, stream

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