Spatial evapotranspiration, rainfall and land use data in water accounting – Part 1: Review of the accuracy of the remote sensing data

Karimi, Poolad; Bastiaanssen, W.G.M.

doi:10.5194/hess-19-507-2015

Cited by 129 publications

(93 citation statements)

References 206 publications

(97 reference statements)

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“…The variability in this case expresses the accuracy and thus confidence that can be attached to the outputs, because the variability of the input parameter space expresses error in the remotely sensed hydrological variables. The space of input parameters in this MC study is defined by a skewed normal distribution as explained by Karimi and Bastiaanssen (2015). The statistical input data are specified in Table 4.…”

Section: Methodology To Express the Reliability Of The Wa+ Frameworkmentioning

confidence: 99%

“…A recent literature review by Karimi and Bastiaanssen (2015) showed that the average errors in land use mapping, and annual or seasonal precipitation and evapotranspiration estimates on the basis of multispectral remote sensing data were 14.5, 18.5, and 5.4 %, respectively. These figures are based on a comprehensive literature review in which for each variable several numbers of post-2000 peer-reviewed publications were consulted for reported differences of satellite-based estimates from conventional ground measurements.…”

Section: P Karimi Et Al: Spatial Evapotranspiration Rainfall and Lmentioning

confidence: 99%

“…Future studies will focus on monthly water accounts though. The degree of inaccuracies in remote sensing data is based on the comprehensive review of Karimi and Bastiaanssen (2015). The objective of the current paper is to study the impact of these errors on the water resources of two WA+ reporting sheets.…”

Section: P Karimi Et Al: Spatial Evapotranspiration Rainfall and Lmentioning

confidence: 99%

“…The goal of this paper is to investigate the difference between the reference data of Table 7 and the results if the remote sensing input data is made variable according to the errors identified by Karimi and Bastiaanssen (2015). For this purpose the average rainfall year 2009 has been analyzed.…”

Section: Probability Distribution Of Wa+ For 2009mentioning

confidence: 99%

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Spatial evapotranspiration, rainfall and land use data in water accounting – Part 2: Reliability of water acounting results for policy decisions in the Awash Basin

Karimi

Bastiaanssen

Sood

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract. Water Accounting Plus (WA+) is a framework that summarizes complex hydrological processes and water management issues in river basins. The framework is designed to use satellite-based measurements of land and water variables and processes as input data. A general concern associated with the use of satellite measurements is their accuracy. This study focuses on the impact of the error in remote sensing measurements on water accounting and information provided to policy makers. The Awash Basin in the central Rift Valley in Ethiopia is used as a case study to explore the reliability of WA+ outputs, in the light of input data errors. The Monte Carlo technique was used for stochastic simulation of WA+ outputs over a period of 3 yr. The results show that the stochastic mean of the majority of WA+ parameters and performance indicators are within 5 % deviation from the original WA+ values based on one single calculation. Stochastic computation is proposed as a standard procedure for WA+ water accounting because it provides the uncertainty bandwidth for every WA+ output, which is essential information for sound decision-making processes. The majority of WA+ parameters and performance indicators have a coefficient of variation (CV) of less than 20 %, which implies that they are reliable and provide consistent information on the functioning of the basin. The results of the Awash Basin also indicate that the utilized flow and basin closure fraction (the degree to which available water in a basin is utilized) have a high margin of error and thus a low reliability. As such, the usefulness of them in formulating important policy decisions for the Awash Basin is limited. Other river basins will usually have a more accurate assessment of the discharge in the river mouth.

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Section: Methodology To Express the Reliability Of The Wa+ Frameworkmentioning

confidence: 99%

Section: P Karimi Et Al: Spatial Evapotranspiration Rainfall and Lmentioning

confidence: 99%

Section: P Karimi Et Al: Spatial Evapotranspiration Rainfall and Lmentioning

confidence: 99%

Section: Probability Distribution Of Wa+ For 2009mentioning

confidence: 99%

See 2 more Smart Citations

Spatial evapotranspiration, rainfall and land use data in water accounting – Part 2: Reliability of water acounting results for policy decisions in the Awash Basin

Karimi

Bastiaanssen

Sood

et al. 2015

Hydrol. Earth Syst. Sci.

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“…These observations are also needed for prognosticating future trends by using modelling approaches that involve calibration and simulation procedures [7]. Additionally, long-term observations of ETa over small watersheds are useful as ground truth for validating remotely sensed products [8].…”

Section: Introductionmentioning

confidence: 99%

Observing Actual Evapotranspiration within a Hilly Watershed: Case Study of the Kamech Site, Cap Bon Peninsula, Tunisia

Zitouna-Chebbi

Prévot

Chakhar

et al. 2017

Proceedings of the 2nd International Electronic Conference on Atmospheric Sciences

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There is a strong need for long term observations of land surface fluxes, especially the latent heat flux (λE), or actual evapotranspiration (ETa), a key component of both the surface energy balance and the hydrological cycle. The eddy covariance (EC) method is widely used to provide measurements of land surface fluxes. However, missing data are inherent to EC measurements and several gap-filling methods have been proposed. Nevertheless, observing ETa by EC and testing gap-filling methods in hilly watersheds received little attention. This study aimed at obtaining continuous ETa time series from EC measurements collected within a small hilly watershed, which implied adapting gap-filling techniques to these particular conditions. The experiment took place within the agricultural watershed Kamech (Northeast Tunisia) which belongs to the OMERE environmental observatory. A 9.6-meter-high EC flux tower was installed in the center of the 2.45 km 2 area watershed. Sensible and latent heat fluxes data collected from 2010 to 2013 were quality controlled. The software REddyProc was used to gap-fill the fluxes at hourly timescale. To account for the combined effects of wind direction and topography, REddyProc was applied after separating the two dominant wind directions, which notably improved the estimated fluxes. Aggregating the hourly λE estimates at daily and monthly timescales allowed analyzing the temporal variability of ETa over the seasons and between years.

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Assessment of reference evapotranspiration across an arid urban environment having poor data monitoring system

Shafieiyoun

Gheysari

Khiadani

et al. 2020

Hydrological Processes

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Estimation of reference evapotranspiration (ET0) in urban areas is challenging but essential in arid urban climates. To evaluate ET0 in an urban environment and non‐urban areas, air temperature and relative humidity were measured at five different sites across the arid city of Isfahan, Iran, over 4 years. Wind speed and sunshine hours were obtained from an urban surrounding weather station over the same period and used to estimate ET0. Calculated ET0 was compared with satellite‐based ET0 retrieved from the MOD16A2 PET product. Although MODIS PET was strongly correlated with the Valiantzas equation, it overestimated ET0 and showed average accuracy (r = 0.93–0.94, RMSE = 1.18–1.28 mm/day, MBE = 0.73–0.84 mm/day). The highest ET0 differences between an urban green space and a non‐urban area were 1.1 and 0.87 mm/day, which were estimated by ground measurements and MODIS PET, respectively. The sensitivity of ET0 to wind speed and sunshine hours indicated a significant effect on cumulative ET0 at urban sites compared to the non‐urban site, which has a considerable impact on the amount of irrigation required in those areas. Although MODIS PET requires improvement to accurately reflect field level microclimate conditions affecting ET0, it is beneficial to hydrological applications and water resource managers especially in areas where data is limited. In addition, our results indicated that using limited data methods or meteorological data from regional weather stations, leads to incorrect estimation of ET0 in urban areas. Therefore, decision‐makers and urban planners should consider the importance of precisely estimating ET0 to optimize management of urban green space irrigation, especially in arid and semi‐arid climates such as the city of Isfahan.

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Spatial evapotranspiration, rainfall and land use data in water accounting – Part 1: Review of the accuracy of the remote sensing data

Cited by 129 publications

References 206 publications

Spatial evapotranspiration, rainfall and land use data in water accounting – Part 2: Reliability of water acounting results for policy decisions in the Awash Basin

Spatial evapotranspiration, rainfall and land use data in water accounting – Part 2: Reliability of water acounting results for policy decisions in the Awash Basin

Observing Actual Evapotranspiration within a Hilly Watershed: Case Study of the Kamech Site, Cap Bon Peninsula, Tunisia

Assessment of reference evapotranspiration across an arid urban environment having poor data monitoring system

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