Monitoring Residual Soil Moisture and Its Association to the Long-Term Variability of Rainfall over the Upper Blue Nile Basin in Ethiopia

Ayehu, Getachew Tesfaye; Tadesse, Tsegaye; Gessesse, Berhan

doi:10.3390/rs12132138

Cited by 8 publications

(2 citation statements)

References 68 publications

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“…However, these studies are rather global and some focus on specific regions of the globe, and less emphasis has been given to the East Africa region. Apart from a few attempts to understand SM residue monitoring (e.g., Ayehu et al 2019) and SM-RF variability (e.g., Ayehu et al 2020) across a river basin in Ethiopia, obtaining a study that covers detailed spatiotemporal characteristics of a soil moisture and its driving factors spanning across the country is limited. Therefore, evaluating such local and remote factors influencing the East African SM spatiotemporal variability is important.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal variability of soil moisture over Ethiopia and its teleconnections with remote and local drivers

Jimma

Demissie

Diro

et al. 2023

Theor Appl Climatol

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Soil moisture is one of the essential climate variables with a potential impact on local climate variability. Despite the importance of soil moisture, studies on soil moisture characteristics in Ethiopia are less documented. In this study, the spatiotemporal variability of Ethiopian soil moisture (SM) has been characterized, and its local and remote influential driving factors are investigated. An empirical orthogonal function (EOF) and KMeans clustering algorithm have been employed to classify the large domain into homogeneous zones. Complex maximum covariance analysis (CMCA) is applied to evaluate the covariability between SM and selected local and remote variables such as rainfall (RF), evapotranspiration (ET), and sea surface temperature (SST). Inter-comparison among SM datasets highlight that the FLDAS dataset better depicts the country’s SM spatial and temporal distribution (i.e., a correlation coefficient $$r=0.95$$ r = 0.95 , $$rmsd=0.04{\mathrm{m}}^{3}{\mathrm{m}}^{-3}$$ r m s d = 0.04 m 3 m - 3 with observations). Results also indicate that regions located in northeastern Ethiopia are drier irrespective of the season (JJAS, MAM, and OND) considered. In contrast, the western part of the country consistently depicted a wetter condition in all seasons. During summer (JJAS), the soil moisture variability is characterized by a strong east–west spatial contrast. The highest and lowest soil moisture values were observed across the country’s central western and eastern parts, respectively. Furthermore, analyses indicate that interannual variability of SM is dictated substantially by RF, though the impact on some regions is weaker. It is also found that ET likely drives the SM in the eastern part of Ethiopia due to a higher atmospheric moisture demand that ultimately invokes changes in surface humidity and rainfall. A composite analysis based on the extreme five wettest and driest SM years revealed a similar spatial distribution of wet SM with positive anomalies of RF across the country and ET over the southern regions. Remote SSTs are also found to have a significant influence on SM distribution. In particular, equatorial central Pacific and western Indian oceans SST anomalies are predominant factors for spatiotemporal SM variations over the country. Major global oceanic indices: Oceanic Nino Index (ONI), Indian Ocean Dipole (IOD), Pacific warm pool (PACWARMPOOL), and Pacific Decadal Oscillations (PDO) are found to be closely associated with the SM anomalies in various parts of the country. The associationship between these remote SST anomalies and local soil moisture is via large-scale atmospheric circulations that are linked to regional factors such as precipitation and temperature anomalies.

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Section: Introductionmentioning

confidence: 99%

Spatiotemporal variability of soil moisture over Ethiopia and its teleconnections with remote and local drivers

Jimma

Demissie

Diro

et al. 2023

Theor Appl Climatol

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“…To improve the seasonal and annual predictability of rainfall, runoff, and ET dynamics across the basin, the available in-situ observations were blended with satellite-derived hydrological data and LSMs outputs [18,24,42,47,48]. Further, several research studies have employed multisource remote sensing observations including precipitation [18,49,50], ET and moisture products [47,51,52], and gridded hydrological records [53][54][55] to understand the water resources potentials in the hydrologic source and sink areas [50], investigate the seasonal variability across the entire NRB [20,56,57], and individual hydrologic units, i.e., Lake Victoria [25,58] and the Blue Nile Basin (BNB) [51,55,59]. Consequently, recent research utilized GRACE-TWS data to study the changes in key water storage components and the hydrological mass variation in the basin [24,58].…”

Section: Introductionmentioning

confidence: 99%

Using GRACE/GRACE-FO, Data-Driven, and Modeling to Assess the Twentieth and Twenty-first Century Water Storage Changes in the Nile River Basin

Hasan¹,

Tarhule²,

Kirstetter³

2021

Preprint

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This research assesses the changes in the total water storage (TWS) during the twentieth century and their future projections in the Nile River Basin (NRB) via TWSA (TWS anomalies) records from GRACE (Gravity Recovery and Climate Experiment), GRACE-FO (Follow-On), data-driven-reanalysis TWSA and land surface model (LSM), in association with precipitation, temperature records, and standard drought indicators. The analytical approach incorporates the development of 100+ yearlong TWSA records using a probabilistic conditional distribution fitting approach by the GAMLSS (Generalized Additive Model for Location, Scale, and Shape) model. The drought and flooding severity, duration, magnitude, frequencies, and recurrence were assessed during the studied period. The results showed, 1- The NRB between 2002 to 2020 has transited to substantial wetter conditions. 2- The TWSA reanalysis records between 1901 to 2002 revealed that the NRB had experienced a positive increase in TWS during the wet and dry seasons. 3- The projected TWSA between 2021 to 2050 indicated slight positive changes in TWSA during the rainy seasons. The analysis of drought and flooding frequencies between 1901 to 2050 indicated the NRB has ~64 dry-years compared to ~86 wet-years. The 100+ yearlong TWSA records assured that the NRB transited to wetter conditions relative to few dry spells. These TWSA trajectories call for further water resources planning in the region especially during flood seasons. This research contributes to the ongoing efforts to improve the TWSA assessment and its associated dynamics for transboundary river basins. It also demonstrates how an extended TWSA record provides unique insights for water resources management in the NRB and similar regions.

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A framework for separating natural and anthropogenic contributions to evapotranspiration of human-managed land covers in watersheds based on machine learning

Zeng

Elnashar

et al. 2022

Science of The Total Environment

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Monitoring Residual Soil Moisture and Its Association to the Long-Term Variability of Rainfall over the Upper Blue Nile Basin in Ethiopia

Cited by 8 publications

References 68 publications

Spatiotemporal variability of soil moisture over Ethiopia and its teleconnections with remote and local drivers

Spatiotemporal variability of soil moisture over Ethiopia and its teleconnections with remote and local drivers

Using GRACE/GRACE-FO, Data-Driven, and Modeling to Assess the Twentieth and Twenty-first Century Water Storage Changes in the Nile River Basin

A framework for separating natural and anthropogenic contributions to evapotranspiration of human-managed land covers in watersheds based on machine learning

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