Dataset Information

Spatiotemporal trends of NDVI and its response to climate variability in the Abbay River Basin, Ethiopia.

ABSTRACT: Woody vegetation plays a vital role in regulating the water budget and energy exchange in the Earth's system. This study aimed at analyzing the spatiotemporal variability of Normalized Difference Vegetation Index (NDVI) and its response to Potential Evapotranspiration (PET), rainfall (RF), soil moisture (SM), and temperature (TEM) in the study area. The trends, correlations, and relationships between NDVI and climate variables were executed using Mann-Kendall monotonic trend (MKMT), partial correlation coefficients (PCC), and multiple linear regression (MLR) methods, respectively. Over the last 26 years, the interannual NDVI increased by 0.0065 yr^-1 (R² = 0.159, p = 0.157). The spatiotemporal MKMT and Theil-Sen slope analysis showed that interannual NDVI increased significantly in 78% of the basin's total area. Of the 78% of the basin, 31%, and 47%, of the total area showed extremely significant increasing (Z_mk = 4.706, p ≤ 0.01), and significant increasing trends (Z_mk = 2.378, p ≤ 0.05) respectively. The interannual variation of NDVI was well explained (R² = 0.88, Adjusted R² = 0.84) by the climate variables in the eastern, southeastern, and central sub-basins where agriculture, grass, sparse vegetation and barelands are the predominant land use land cover (LULC) classes. The main climatic factors that control vegetation growth and greenness during the rainy season were found to be PET, SM, and RF with 0.91, 0.99, and 0.86 PCC with NDVI respectively. The current study broadens the scientific community's understanding of the relationship between climate variables and vegetation growth in highland ecosystems. Understanding the seasonal and long-term relationship between climate and NDVI contributes to the scientific knowledge of highland ecosystems, which are extremely vulnerable to climate change.

SUBMITTER: Hussien K

PROVIDER: S-EPMC10006846 | biostudies-literature | 2023 Mar

REPOSITORIES: biostudies-literature

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Spatiotemporal trends of NDVI and its response to climate variability in the Abbay River Basin, Ethiopia.

Hussien Kassaye K Kebede Asfaw A Mekuriaw Asnake A Beza Solomon Asfaw SA Erena Sitotaw Haile SH

Heliyon 20230228 3

Woody vegetation plays a vital role in regulating the water budget and energy exchange in the Earth's system. This study aimed at analyzing the spatiotemporal variability of Normalized Difference Vegetation Index (NDVI) and its response to Potential Evapotranspiration (PET), rainfall (RF), soil moisture (SM), and temperature (TEM) in the study area. The trends, correlations, and relationships between NDVI and climate variables were executed using Mann-Kendall monotonic trend (MKMT), partial corr ...[more]

PMID: 36915532

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Project description:Ethiopia, despite contributing minimally to global greenhouse gas emissions, is consistently cited as one of the most vulnerable countries, not only in Sub-Saharan Africa regions but also globally, to climate variability and change. The country's farming households are most vulnerable because of their climate-sensitive livelihoods and limited resources to finance adaptation measures. This study aimed to assess the livelihood vulnerability of communities reliant on a mixed crop-livestock agricultural system and natural resources in the Central Rift Valley sub-basin of Ethiopia to climate variability and change. Structured interviews were used to collect quantitative data from 339 randomly selected households. Livelihood Vulnerability Index was developed to assess the degree of livelihood vulnerability between the two districts. The survey results were supported and substantiated by focus group discussions. The findings show that farm households living in the sub-basin experience different levels of vulnerability to climate variability and change because of their varying adaptive capacities. Considering the aggregate Livelihood Vulnerability Index, Arsi Negele district is considered to be more vulnerable to climate variability and change. The livelihood Vulnerability Index-Intergovernmental Panel on Climate Change results also show that Arsi Negele is more vulnerable since its exposure scores exceed its adaptive capacity. Several factors contribute to the weak adaptive capacity of farmers in Arsi Negele. These factors include lesser adoption of agricultural technology, a low level of knowledge and education, insufficient social networks, less diversification of livelihood strategies, and higher socio-demographic vulnerability. In contrast, Adami Tullu Jido Kombolcha district has a higher sensitivity score due to its limited access to potable water, housing, and land ownership. Strategies that minimize households' degree of sensitivity and enhance their adaptive capacity should be promoted. Such strategies should include the adoption of improved agricultural technologies, strengthening awareness and technical capacity, promoting better soil and water management, accessing credit options, and building community networks. Diversifying household income and establishing alternative livelihoods should also be encouraged.

Project description:It is important to determine long-term changes in vegetation cover, and the associated driving forces, to better understand the natural and human-induced factors affecting vegetation growth. We calculated the fractional vegetation coverage (FVC) of the Urumqi River basin and selected seven natural factors (the clay and sand contents of surface soils, elevation, aspect, slope, precipitation and temperature) and one human factor (land use type). We then used the Sen-Man-Kendall method to calculate the changing trend of the FVC from 2000 to 2020. We used the optimal parameters-based geographical detector (OPGD) model to quantitatively analyze the influence of each factor on the change in vegetation coverage in the basin. The FVC of the Urumqi River basin fluctuated from 2000 to 2020, with average values between 0.22 and 0.33. The areas with no and low vegetation coverage accounted for two-thirds of the total area, whereas the areas with a medium, medium-high and high FVC accounted for one-third of the total area. The upper reaches of the river basin are glacial and forest areas with no vegetation coverage and a high FVC. The middle reaches are concentrated in areas of urban construction with a medium FVC. The lower reaches are in unstable farmland with a medium and high FVC and deserts with a low FVC and no vegetation. From the perspective of the change trend, the areas with an improved FVC accounted for 62.54% of the basin, stable areas accounted for 5.66% and degraded areas accounted for 31.8%. The FVC showed an increasing trend in the study area. The improvement was mainly in the areas of urban construction and desert. Degradation occurred in the high-elevation areas, whereas the transitional zone was unchanged. The analysis of driving forces showed that the human factor explained more of the changes in the FVC than the natural factors in the order: land use type (0.244) > temperature (0.216) > elevation (0.205) > soil clay content (0.172) > precipitation (0.163) > soil sand content (0.138) > slope (0.059) > aspect (0.014). Apart from aspect, the explanatory power (Q value) of the interaction of each factor was higher than that of the single factor. Risk detection showed that each factor had an interval in which the change in the FVC was inhibited or promoted. The optimum elevation interval of the study area was 1300-2700 m and the greatest inhibition of the FVC was seen above 3540 m. Too much or too little precipitation inhibited vegetation coverage.

Dataset Information

Spatiotemporal trends of NDVI and its response to climate variability in the Abbay River Basin, Ethiopia.

Publications

Spatiotemporal trends of NDVI and its response to climate variability in the Abbay River Basin, Ethiopia.

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