scholarly journals Assessing Annual Actual Evapotranspiration Based on Climate, Topography and Soil in Natural and Agricultural Ecosystems

Climate ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 20
Author(s):  
Kleoniki Demertzi ◽  
Vassilios Pisinaras ◽  
Emanuel Lekakis ◽  
Evangelos Tziritis ◽  
Konstantinos Babakos ◽  
...  
Keyword(s):  
Water Balance ◽  
Large Scale ◽  
Hydrological Model ◽  
Actual Evapotranspiration ◽  
Irrigated Agriculture ◽  
Climate Data ◽  
Natural Ecosystems ◽  
Loading Effects ◽  
Very High ◽  
Of Greece

Simple formulas for estimating annual actual evapotranspiration (AET) based on annual climate data are widely used in large scale applications. Such formulas do not have distinct compartments related to topography, soil and irrigation, and for this reason may be limited in basins with high slopes, where runoff is the dominant water balance component, and in basins where irrigated agriculture is dominant. Thus, a simplistic method for assessing AET in both natural ecosystems and agricultural systems considering the aforementioned elements is proposed in this study. The method solves AET through water balance based on a set of formulas that estimate runoff and percolation. These formulas are calibrated by the results of the deterministic hydrological model GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) for a reference surface. The proposed methodology is applied to the country of Greece and compared with the widely used climate-based methods of Oldekop, Coutagne and Turk. The results show that the proposed methodology agrees very well with the method of Turk for the lowland regions but presents significant differences in places where runoff is expected to be very high (sloppy areas and areas of high rainfall, especially during December–February), suggesting that the proposed method performs better due to its runoff compartment. The method can also be applied in a single application considering irrigation only for the irrigated lands to more accurately estimate AET in basins with a high percentage of irrigated agriculture.

Modelling seasonal evapotranspiration of arid lands in China

2011 ◽  
Vol 42 (1) ◽  
pp. 40-49 ◽  
Author(s):  
Yuanrun Zheng ◽  
Zhixiao Xie ◽  
Charles Roberts ◽  
Ping An ◽  
Xiangjun Li ◽  
...  
Keyword(s):  
Water Balance ◽  
Water Resource Management ◽  
Numerical Models ◽  
Field Measurements ◽  
Western China ◽  
Actual Evapotranspiration ◽  
Climate Data ◽  
Robust Model ◽  
Proposed Model ◽  
Local Soil

The measurement of actual evapotranspiration, a key term in the water balance equation, has become a very important issue. Many good methods exist for estimating actual evapotranspiration; however, most of these require complicated inputs. Here, a simple but robust model for estimation of actual evapotranspiration in arid areas of western China is proposed. This model is a visual system with a user-friendly interface in the STELLA (a commercial software package for building numerical models) environment combined with two existing water balance equations and local soil and climate data to ensure its easy application in developing areas. Validation with field measurements revealed that the estimated values of actual evapotranspiration obtained using the model are in agreement with the observed values. Both the established Choudhury model and the proposed model produced similar estimates when the actual annual evapotranspiration is below 200 mm, but the model proposed simulates real-world conditions more precisely when the actual annual evapotranspiration is greater than 200 mm. Another advantage of the proposed model is that it uses simple and reliable climate data that are readily available from the network of weather stations in China. The simulation results could serve as a relatively good reference for water resource management in this area.

scholarly journals Sensitivity of simulated global-scale freshwater fluxes and storages to input data, hydrological model structure, human water use and calibration

2014 ◽  
Vol 18 (9) ◽  
pp. 3511-3538 ◽  
Author(s):  
H. Müller Schmied ◽  
S. Eisner ◽  
D. Franz ◽  
M. Wattenbach ◽  
F. T. Portmann ◽  
...  
Keyword(s):  
Land Cover ◽  
Water Use ◽  
River Discharge ◽  
Hydrological Model ◽  
Grid Cell ◽  
Global Scale ◽  
Climate Forcing ◽  
Actual Evapotranspiration ◽  
Climate Data ◽  
Freshwater Fluxes

Abstract. Global-scale assessments of freshwater fluxes and storages by hydrological models under historic climate conditions are subject to a variety of uncertainties. Using the global hydrological model WaterGAP (Water – Global Assessment and Prognosis) 2.2, we investigated the sensitivity of simulated freshwater fluxes and water storage variations to five major sources of uncertainty: climate forcing, land cover input, model structure/refinements, consideration of human water use and calibration (or no calibration) against observed mean river discharge. In a modeling experiment, five variants of the standard version of WaterGAP 2.2 were generated that differed from the standard version only regarding the investigated source of uncertainty. The basin-specific calibration approach for WaterGAP was found to have the largest effect on grid cell fluxes as well as on global AET (actual evapotranspiration) and discharge into oceans for the period 1971–2000. Regarding grid cell fluxes, climate forcing ranks second before land cover input. Global water storage trends are most sensitive to model refinements (mainly modeling of groundwater depletion) and consideration of human water use. The best fit to observed time series of monthly river discharge or discharge seasonality is obtained with the standard WaterGAP 2.2 model version which is calibrated and driven by daily reanalysis-based WFD/WFDEI (combination of Watch Forcing Data based on ERA40 and Watch Forcing Data based on ERA-Interim) climate data. Discharge computed by a calibrated model version using monthly CRU TS (Climate Research Unit time-series) 3.2 and GPCC (Global Precipitation Climatology Center) v6 climate input reduced the fit to observed discharge for most stations. Taking into account uncertainties of climate and land cover data, global 1971–2000 discharge into oceans and inland sinks ranges between 40 000 and 42 000 km3 yr−1. Global actual evapotranspiration, with 70 000 km3 yr−1, is rather unaffected by climate and land cover uncertainties. Human water use reduced river discharge by 1000 km3 yr−1, such that global renewable water resources are estimated to range between 41 000 and 43 000 km3 yr−1. The climate data sets WFD (available until 2001) and WFDEI (starting in 1979) were found to be inconsistent with respect to shortwave radiation data, resulting in strongly different actual evapotranspiration. Global assessments of freshwater fluxes and storages would therefore benefit from the development of a global data set of consistent daily climate forcing from 1900 to present.

Modeling the effect of flood and drip irrigation on groundwater recharge

2020 ◽  
Author(s):  
Sandra Pool ◽  
Félix Francés ◽  
Alberto Garcia-Prats ◽  
Cristina Puertes ◽  
Manuel Pulido-Velázquez ◽  
...  
Keyword(s):  
Water Balance ◽  
Groundwater Recharge ◽  
Drip Irrigation ◽  
Hydrological Model ◽  
Agricultural Area ◽  
Annual Rainfall ◽  
Irrigated Agriculture ◽  
Irrigation Technology ◽  
Simulation Results ◽  
Irrigation Modernization

<p>Irrigation modernization, here defined as the replacement of traditional flood irrigation systems by pressurized drip-irrigation technology, has been widely promoted with the aim to move towards a more sustainable use of freshwater resources in irrigated agriculture. However, the scale sensitivity of irrigation efficiency challenged the predominantly positive value attributed to irrigation modernization and asked for an integrated evaluation of the technological change at various scales. The aim of this study is therefore to contribute to an improved understanding of the hydrological functioning in a landscape under irrigation modernization. We used local field observations to propose a regional scale modeling approach that allowed to specifically simulate the difference in water balance as a function of irrigation method and crop type. The approach focused on the modification of the spatial input data and had therefore the benefit of being relatively independent of the final choice of the hydrological model. We applied the proposed approach to the semi-arid agricultural area of Valencia (Spain), where regional information about the use of irrigation technologies and irrigation volumes at farm level were available. The distributed hydrological model Tetis was chosen to simulate the daily water balance from 1994 to 2015 for an area of 913 km<sup>2</sup> at a spatial resolution of 200 m. Model simulations were based on a random selection of parameter values that were subsequently evaluated in a multi-objective calibration framework. Multiple process scales were addressed within the framework by considering the annual evaporative index, monthly groundwater level dynamics, and daily soil moisture dynamics for evaluation. Simulation results were finally analyzed with a focus on groundwater recharge, which is of particular interest for environmental challenges faced within the study area. Simulation results of groundwater recharge for the entire agricultural area indicated a considerable variability in annual recharge (values from 112 mm up to 337 mm), whereby recharge was strongly controlled by annual rainfall volumes. Annual recharge in flood-irrigated areas tended to exceed annual recharge in drip irrigated-areas except for years with above average rainfall volumes. The observed rainfall dependency could be explained by the fact that recharge in drip-irrigated areas almost exclusively occurred during rainy days, whereby a few heavy rainfall events could produce the majority of annual recharge. Our results indicated interesting differences but also commonalities in groundwater recharge for flood and drip irrigation, and therefore emphasized the importance of explicitly considering irrigation technology when modelling irrigated agricultural areas.</p>

scholarly journals Simulation and analysis of the impact of projected climate change on the spatially distributed waterbalance in Thuringia, Germany

2009 ◽  
Vol 21 ◽  
pp. 33-48 ◽  
Author(s):  
P. Krause ◽  
S. Hanisch
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Hydrological Model ◽  
Actual Evapotranspiration ◽  
Climate Data ◽  
Runoff Generation ◽  
Entire Area ◽  
Spatially Distributed ◽  
The Impact ◽  
Conceptual Hydrological Model

Abstract. The impact of projected climate change on the long-term hydrological balance and seasonal variability in the federal German state of Thuringia was assessed and analysed. For this study projected climate data for the scenarios A2 and B1 were used in conjunction with a conceptual hydrological model. The downscaled climate data are based on outputs of the general circulation model ECHAM5 and provide synthetic climate time series for a large number of precipitation and climate stations in Germany for the time period of 1971 to 2100. These data were used to compute the spatially distributed hydrological quantities, i.e. precipitation, actual evapotranspiration and runoff generation with a conceptual hydrological model. This paper discusses briefly the statistical downscaling method and its validation in Thuringia and includes an overview of the hydrological model. The achieved results show that the projected climate conditions in Thuringia follow the general European climate trends – increased temperature, wetter winters, drier summers. But, in terms of the spatial distribution and interannual variability regional differences occur. The analysis showed that the general increase of the winter precipitation is more distinct in the mid-mountain region and less pronounced in the lowland whereas the decrease of summer precipitation is higher in the lowland and less distinct in the mid-mountains. The actual evapotranspiration showed a statewide increase due to higher temperatures which is largest in the summer period. The resulting runoff generation in winter was found to increase in the mid-mountains and to slightly decrease in the lowland region. In summer and fall a decrease in runoff generation was estimated for the entire area due to lower precipitation and higher evapotranspiration rates. These spatially differentiated results emphasize the need of high resolution climate input data and distributed modelling for regional impact analyses.

scholarly journals Frequencies of drought at Ranchi regions, Jharkhand

MAUSAM ◽  
2021 ◽  
Vol 60 (4) ◽  
pp. 455-460
Author(s):  
P. K. SINGH ◽  
L. S. RATHORE ◽  
B. ATHIYAMAN ◽  
K. K. SINGH ◽  
A. K. BAXLA ◽  
...  
Keyword(s):  
Water Balance ◽  
Water Deficit ◽  
Aridity Index ◽  
Actual Evapotranspiration ◽  
Severe Drought ◽  
Climate Data ◽  
Moderate Drought ◽  
Annual Water ◽  
Water Surplus ◽  
Probability Analyses

Studies of water balance have been carried out for Ranchi taking 35 years (1970-2004) of climate data. Ranchi has annual water need of 1754 mm, rainfall of 1460 mm, actual evapotranspiration (AE) of 860 mm, water surplus (WS) of 600 mm and water deficit (WD) of 894 mm. The aridity index values were analyzed to assess the frequency of drought experienced of this region. The study reveals that during the above period, Ranchi has experienced 11 percent of large drought and severe drought, but only 3 per cent disastrous droughts in 35 years. Moderate drought category is observed to be most common with 23 per cent probability. Analyses of periods will contagious drought indicate that during the five year period 1980-84 and 1995-99, moderate, large and severe droughts were experienced.

Assessing GlobWat model sensitivity to climate forcing

2020 ◽  
Author(s):  
Banafsheh Abdollahi ◽  
Rolf Hut ◽  
Nick van de Giesen
Keyword(s):  
Input Data ◽  
Large Scale ◽  
Hydrological Modeling ◽  
Hydrological Cycle ◽  
Climate Forcing ◽  
Irrigated Agriculture ◽  
Data Sets ◽  
Climate Data ◽  
Data Set ◽  
Water Abstraction

<p>Irrigation is crucial for sustaining food security for the growing population around the world. Irrigation affects the hydrological cycle both directly, during the process of water abstraction and irrigation, and indirectly, because of infrastructures that have been built in support of irrigation, such as canals, dams, reservoirs, and drainage systems. For evaluating the availability of freshwater resources in the light of growing food demand, modeling the global hydrological cycle is vital. The GlobWat model is one of the models that have been designed for large scale hydrological modeling, with a specific focus on considering irrigated agriculture water use. Both models’ underlying assumptions and the global input data sets used to feed the model could be sources of uncertainty in the output. One of the most challenging input data sets in global hydrological models is the climate input data set. There are several climate forcings available on a global scale like ERA5 and ERA-Interim. In this study, we assess the sensitivity of the GlobWat model to these climate forcing. Pre-processing climate data at a large scale used to be difficult. Recently, this has become much easier by data and scripts provided by eWaterCycle team at the eSience center, Amsterdam, The Netherlands. We will use eWaterCycle's freely available data sources for our assessment and then we will compare the model results with observed data at a local scale.</p>

Integrating Climate and Socio-Economic Scenarios in a Hydrological Model for the Santa River Basin, Peru

2020 ◽  
Author(s):  
Claudia Teutsch ◽  
Faizan Anwar ◽  
Jochen Seidel ◽  
András Bárdossy ◽  
Christian Huggel ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Water Balance ◽  
Water Use ◽  
Water Availability ◽  
Hydrological Model ◽  
Irrigated Agriculture ◽  
Domestic Water ◽  
Study Region ◽  
River Catchment

<p>High mountain regions, like the Andes, face various risks due to climate change. In the Santa River catchment in Peru which includes the glaciated Cordillera Blanca, water availability is threatened by many climatic and non-climatic impacts. The water resources in the catchment heavily rely on seasonal precipitation and during the dry season glacier melt water plays an important role. However, both, precipitation patterns and glacier extent are affected by climate change impacts. Additionally, socio-economic changes put further pressure on water resources and hence on water availability.</p> <p>Within the AguaFuturo Project we established a conceptual integrated water balance model based on a semi-distributed HBV model for the data scarce Santa River catchment. The hydrological model processes are extended by feedback loops for agricultural and domestic water use. The model runs on daily time scale and includes two hydrological response units. One includes the irrigated agricultural areas which are predominately located in the valley of the catchment; the other includes non-irrigated areas and domestic water use.</p> <p>To assess future water balance challenges we downscaled and disaggregated monthly CORDEX scenarios for 2020-2050 using information from the new Peruvian precipitation dataset PISCO (Peruvian Interpolated data of the SENAMHI’s Climatological and hydrological Observations) for simulations of future changes in hydro-climatology. In the model, these climate scenarios are combined with possible socio-economic scenarios which are translated into time series for domestic and agricultural water demand. The socio-economic scenarios are developed by using the Cross-Impact-Balance-Analysis (CIB), a method used for analyzing impact networks. Using CIB, the interrelations between 15 social, economic and policy descriptors were analyzed and as a result a total of 29 possible consistent scenarios were determined. For further analysis and validation of these scenarios a participatory process was included, involving local experts and stakeholders of the study region.</p> <p>The climate and socio-economic scenarios are independent and can be combined randomly. The uncertainties of the climatic and socio-economic scenarios are quantified by Monte Carlo simulations.</p> <p>The output of the model runs is an ensemble of possible future discharges of the Santa River, which can be further analyzed statistically to assess the range of the possible discharges. This evaluation provides an estimate of the probability of water shortages, especially with regard to conflict potential with hydropower production and the large scale irrigated agriculture areas in the adjacent coastal desert which also rely on water from the Santa River.</p>

scholarly journals A long-term record of blended satellite and in situ sea surface temperature for climate monitoring, modeling and environmental studies

2016 ◽  
Author(s):  
V. Banzon ◽  
T. M. Smith ◽  
C. Liu ◽  
W. Hankins
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Large Scale ◽  
Sea Surface ◽  
Climate Data ◽  
Volcanic Aerosols ◽  
Climate Data Record ◽  
Very High

Abstract. This paper describes a blended sea-surface temperature (SST) dataset that is part of the National Oceanic and Atmospheric Administration (NOAA) Climate Data Record (CDR) Program product suite. Using optimum interpolation (OI), in situ and satellite observations are combined on a daily and 0.25° spatial grid to form an SST analysis, i.e., a spatially complete field. A large-scale bias adjustment of the input infrared SSTs is made using buoy and ship observations as a reference. This is particularly important for the time periods when volcanic aerosols from the El Chichon and Mt. Pinatubo eruptions are widespread globally. The main source of SSTs is the Advanced Very High Resolution Radiometer (AVHRR), available from late 1981 to the present, which is also the temporal span of this CDR. The input and processing choices made to ensure a consistent dataset that meets the CDR requirements is summarized. A brief history and an explanation of the forward production schedule for the preliminary and science-quality final product is also provided. The dataset is produced and archived at the newly formed National Centers for Environmental Information (NCEI) in Network Common Data Form (netCDF) at http://doi.org/doi:10.7289/V5SQ8XB5 .

scholarly journals Estimation of evapotranspiration using a simulation model

2012 ◽  
Vol 9 (2) ◽  
pp. 257-266
Author(s):  
MH Ali ◽  
H Paul ◽  
MR Haque
Keyword(s):  
Water Balance ◽  
Simulation Model ◽  
Standard Error ◽  
Coefficient Of Variation ◽  
Actual Evapotranspiration ◽  
Irrigated Agriculture ◽  
Accurate Estimation ◽  
Statistical Parameters ◽  
Budget Model ◽  
Simulation Performance

Practical methods for the accurate estimation of water requirement for irrigated agriculture are essential. Simulation  model is a useful tool to estimate water balance in the crop field. In this study, the BUDGET model was used to  evaluate its performance to simulate water balance in wheat field. The BUDGET model is composed of a set of  validated subroutines describing the various processes involved in water extraction by plant roots and soil water  movement in absence of a water table. The model was run to simulate evapotranspiration values with the actual  observed weather, crop and soil data for three years (2002-2005), obtained from experimental Station of Bangladesh  Institute of Nuclear Agricultural (BINA). The input data of model are separated into four stages and the value of Kc  and root depth are different for each stage. Evaluation of model performance is done with both graphical display and  statistical criteria. The simulated values fall close to 1:1 line, indicating better performance. The statistical parameters  such as standard deviation (SD), standard error (SE), coefficient of variation (CV) of simulated and actual  evapotranspiration values are found 21.07 and 29.23; 4.49 and 6.23; and 38.03 and 50.75, respectively. Both the  standard error and coefficient of variation for simulated values are found lower than the observed values indicating  stability of the model output. The coefficient of determination value (R2 =0.83) is high for this model, which indicates  good simulation performance. The relative error (RE) is 23.28 percent and model efficiency (EF) is 78.95 percent  which means that the simulation of actual evapotranspiration is satisfactory. The value of Index of agreement (IA) is  0.918 which indicates a very good performance of the model. The overall statistical parameters of simulation period  are in satisfactory level. Therefore, the BUDGET model is able to predict actual evapotranspiration for any level of  soil moisture with reasonable accuracy. The model can be used in planning, management and operation of an  irrigation project for judicious use of water with the limited inputs, especially suitable for countries where modeling of  crop yield is needed under water stress conditions.   DOI: http://dx.doi.org/10.3329/jbau.v9i2.11038   J. Bangladesh Agril. Univ. 9(2): 257–266, 2011

scholarly journals Shell-crossing in a ΛCDM Universe

2020 ◽  
Vol 501 (1) ◽  
pp. L71-L75
Author(s):  
Cornelius Rampf ◽  
Oliver Hahn
Keyword(s):  
Dark Matter ◽  
Perturbation Theory ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Three Dimensional ◽  
Random Initial Data ◽  
Recursion Relations ◽  
Indispensable Tool ◽  
First Time ◽  
Very High

ABSTRACT Perturbation theory is an indispensable tool for studying the cosmic large-scale structure, and establishing its limits is therefore of utmost importance. One crucial limitation of perturbation theory is shell-crossing, which is the instance when cold-dark-matter trajectories intersect for the first time. We investigate Lagrangian perturbation theory (LPT) at very high orders in the vicinity of the first shell-crossing for random initial data in a realistic three-dimensional Universe. For this, we have numerically implemented the all-order recursion relations for the matter trajectories, from which the convergence of the LPT series at shell-crossing is established. Convergence studies performed at large orders reveal the nature of the convergence-limiting singularities. These singularities are not the well-known density singularities at shell-crossing but occur at later times when LPT already ceased to provide physically meaningful results.

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