Mapping Root Zone Soil Moisture Using Remotely Sensed Optical Imagery

Scott, Christopher A.; Bastiaanssen, W.G.M.; Ahmad, Mobin-ud-Din

doi:10.1061/(asce)0733-9437(2003)129:5(326)

Cited by 107 publications

(106 citation statements)

References 40 publications

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“…The net short wave radiation and net long wave radiation were computed based on short wave transmittance through the atmosphere. The amount of soil moisture in the root zone (∼1 m of the top soil layer) is determined empirically from the evaporative fraction (Scott et al, 2003). The evaporation computed from SEBAL has been validated by checking water balance computations of 3 sub basins: Sudd, Bahr el Ghazal downstream discharge stations and Sobat (Mohamed et al, 2004).…”

Section: Evaporation Datamentioning

confidence: 99%

Hydroclimatology of the Nile: results from a regional climate model

Mohamed

Hurk

Savenije

et al. 2005

Hydrol. Earth Syst. Sci.

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Abstract. This paper presents the result of the regional coupled climatic and hydrologic model of the Nile Basin. For the first time the interaction between the climatic processes and the hydrological processes on the land surface have been fully coupled. The hydrological model is driven by the rainfall and the energy available for evaporation generated in the climate model, and the runoff generated in the catchment is again routed over the wetlands of the Nile to supply moisture for atmospheric feedback. The results obtained are quite satisfactory given the extremely low runoff coefficients in the catchment.The paper presents the validation results over the subbasins: Blue Nile, White Nile, Atbara river, the Sudd swamps, and the Main Nile for the period 1995 to 2000. Observational datasets were used to evaluate the model results including radiation, precipitation, runoff and evaporation data. The evaporation data were derived from satellite images over a major part of the Upper Nile. Limitations in both the observational data and the model are discussed. It is concluded that the model provides a sound representation of the regional water cycle over the Nile. The sources of atmospheric moisture to the basin, and location of convergence/divergence fields could be accurately illustrated. The model is used to describe the regional water cycle in the Nile basin in terms of atmospheric fluxes, land surface fluxes and land surface-climate feedbacks. The monthly moisture recycling ratio (i.e. locally generated/total precipitation) over the Nile varies between 8 and 14%, with an annual mean of 11%, which implies that 89% of the Nile water resources originates from outside the basin physical boundaries. The monthly precipitation efficiency varies between 12 and 53%, and the annual mean is 28%. The mean annual result of the Nile regional water cycle is compared to that of the Amazon and the Mississippi basins.Correspondence to: Y. A. Mohamed (yasir1@unesco-ihe.org)

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Section: Evaporation Datamentioning

confidence: 99%

Hydroclimatology of the Nile: results from a regional climate model

Mohamed

Hurk

Savenije

et al. 2005

Hydrol. Earth Syst. Sci.

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“…Knowledge of the soil moisture profile during the irrigation cycle is essential to achieve maximum irrigation efficiency. Soil moisture at shallow depths is known to be extremely variable temporally [10] and can show significant variability with depth (z) [11]. Therefore, frequent in situ soil moisture monitoring is required.…”

Section: Introductionmentioning

confidence: 99%

Modeling Soil Moisture Profiles in Irrigated Fields by the Principle of Maximum Entropy

Mishra

Ellenburg

Al‐Hamdan

et al. 2015

Entropy

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Vertical soil moisture profiles based on the principle of maximum entropy (POME) were validated using field and model data and applied to guide an irrigation cycle over a maize field in north central Alabama (USA). The results demonstrate that a simple two-constraint entropy model under the assumption of a uniform initial soil moisture distribution can simulate most soil moisture profiles that occur in the particular soil and climate regime that prevails in the study area. The results of the irrigation simulation demonstrated that the POME model produced a very efficient irrigation strategy with minimal losses (about 1.9% of total applied water). However, the results for finely-textured (silty clay) soils were problematic in that some plant stress did develop due to insufficient applied water. Soil moisture states in these soils fell to around 31% of available moisture content, but only on the last day of the drying side of the irrigation cycle. Overall, the POME approach showed promise as a general strategy to guide irrigation in humid environments, such as the Southeastern United States.

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“…The partitioning of surface fluxes, in this case Λ, was used as an indicator of SM based on the argument that the observed difference between the actual and potential evapotranspiration is caused by the available water in the root zone [13]. The importance of SM on the evapotranspiration process of plants has been reported positively in dry and negatively in wet climates [37].…”

Section: Discussionmentioning

confidence: 99%

“…The importance of SM on the evapotranspiration process of plants has been reported positively in dry and negatively in wet climates [37]. Nevertheless, similar methods have provided successful results in various climates (Pakistan, Mexico, Brazil, Ghana and others), at extreme conditions (near the permanent wilting point of crops or at field capacity), using Landsat and MODIS satellite images [13,46,47].…”

Section: Discussionmentioning

confidence: 99%

Spatial and Temporal Distribution of Soil Moisture at the Catchment Scale Using Remotely-Sensed Energy Fluxes

Alexandridis

Cherif

Bilas

et al. 2016

Water

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Despite playing a critical role in the division of precipitation between runoff and infiltration, soil moisture (SM) is difficult to estimate at the catchment scale and at frequent time steps, as is required by many hydrological, erosion and flood simulation models. In this work, an integrated methodology is described to estimate SM at the root zone, based on the remotely-sensed evaporative fraction (Λ) and ancillary information on soil and meteorology. A time series of Terra MODIS satellite images was used to estimate SM maps with an eight-day time step at a 250-m spatial resolution for three diverse catchments in Europe. The study of the resulting SM maps shows that their spatial variability follows the pattern of land cover types and the main geomorphological features of the catchment, and their temporal pattern follows the distribution of rain events, with the exception of irrigated land. Field surveys provided in situ measurements to validate the SM maps' accuracy, which proved to be variable according to site and season. In addition, several factors were analyzed in order to explain the variation in the accuracy, and it was shown that the land cover type, the soil texture class, the temporal difference between the datasets' acquisition and the presence of rain events during the measurements played a significant role, rather than the often referred to scale difference between in situ and satellite observations. Therefore, the proposed methodology can be used operationally to estimate SM maps at the catchment scale, with a 250-m spatial resolution and an eight-day time step.

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Mapping Root Zone Soil Moisture Using Remotely Sensed Optical Imagery

Cited by 107 publications

References 40 publications

Hydroclimatology of the Nile: results from a regional climate model

Hydroclimatology of the Nile: results from a regional climate model

Modeling Soil Moisture Profiles in Irrigated Fields by the Principle of Maximum Entropy

Spatial and Temporal Distribution of Soil Moisture at the Catchment Scale Using Remotely-Sensed Energy Fluxes

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