scholarly journals Monitoring the variations of evapotranspiration due to the land use/cover changes in a semiarid shrubland

2016 ◽  
Author(s):  
Tingting Gong ◽  
Huimin Lei ◽  
Dawen Yang ◽  
Hanbo Yang ◽  
Yang Jiao
Keyword(s):  
Land Use ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Hydrological Cycle ◽  
Potential Evapotranspiration ◽  
Degradation Process ◽  
Observation Data ◽  
Predominant Factor ◽  
Semiarid Shrubland ◽  
Positive Effect

Abstract. Evapotranspiration (ET) is an important process in the hydrological cycle, and vegetation change is a primary factor that affects ET. In this study, an attempt is made to analyze the annual and inter-annual characteristics of ET using continuous observation data from eddy-covariance (EC) measurements over four periods (1st July 2011 to 30th June 2015) at a study site located in the Mu Us Sandland of China. Normalized vegetation index (NDVI) was the predominant factor that influences the seasonal variation in ET. Normalization method was adopted to exclude the effects of potential evapotranspiration (ETP) and soil water stress (fs) on ET. Vegetation phenological process was validated to have a remarkable positive effect on normalized ET in a rate of 1.86 (the slope of normalized ET per NDVI) along with vegetation greening. Both on the land degradation process and vegetation rehabilitation process, ET and normalized ET increased. We discussed several possibilities that might lead to the increase. Our work may promote our knowledge about the characteristics of ET of the mix land use/cover condition (sparse shrubland and grassland) in the fragile ecosystem of Mu Us Sandland.

scholarly journals Monitoring the variations of evapotranspiration due to land use/cover change in a semiarid shrubland

2017 ◽  
Vol 21 (2) ◽  
pp. 863-877 ◽  
Author(s):  
Tingting Gong ◽  
Huimin Lei ◽  
Dawen Yang ◽  
Yang Jiao ◽  
Hanbo Yang
Keyword(s):  
Land Use ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Hydrological Cycle ◽  
Vegetation Type ◽  
Soil Surface ◽  
Surface Characteristics ◽  
Observation Data ◽  
Semiarid Shrubland

Abstract. Evapotranspiration (ET) is an important process in the hydrological cycle, and vegetation change is a primary factor that affects ET. In this study, we analyzed the annual and inter-annual characteristics of ET using continuous observation data from eddy covariance (EC) measurement over 4 years (1 July 2011 to 30 June 2015) in a semiarid shrubland of Mu Us Sandy Land, China. The Normalized Difference Vegetation Index (NDVI) was demonstrated as the predominant factor that influences the seasonal variations in ET. Additionally, during the land degradation and vegetation rehabilitation processes, ET and normalized ET both increased due to the integrated effects of the changes in vegetation type, topography, and soil surface characteristics. This study could improve our understanding of the effects of land use/cover change on ET in the fragile ecosystem of semiarid regions and provide a scientific reference for the sustainable management of regional land and water resources.

scholarly journals NDVI-Based Vegetation Change in Inner Mongolia from 1982 to 2006 and Its Relationship to Climate at the Biome Scale

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Linghui Guo ◽  
Shaohong Wu ◽  
Dongsheng Zhao ◽  
Yunhe Yin ◽  
Guoyong Leng ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Inner Mongolia ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Potential Evapotranspiration ◽  
Vegetation Type ◽  
Growing Season ◽  
Desert Steppe

Based on the normalized difference vegetation index (NDVI), we analyzed vegetation change of the six major biomes across Inner Mongolia at the growing season and the monthly timescales and estimated their responses to climate change between 1982 and 2006. To reduce disturbance associated with land use change, those pixels affected by land use change from the 1980s to 2000s were excluded. At the growing season scale, the NDVI increased weakly in the natural ecosystems, but strongly in cropland. Interannual variations in the growing season NDVI for forest was positively linked with potential evapotranspiration and temperature, but negatively correlated with precipitation. In contrast, it was positively correlated with precipitation, but negatively related to potential evapotranspiration for other natural biomes, particularly for desert steppe. Although monthly NDVI trends were characterized as heterogeneous, corresponding to monthly variations in climate change among biome types, warming-related NDVI at the beginning of the growing season was the main contributor to the NDVI increase during the growing season for forest, meadow steppe, and typical steppe, but it constrained the NDVI increase for desert steppe, desert, and crop. Significant one-month lagged correlations between monthly NDVI and climate variables were found, but the correlation characteristics varied greatly depending on vegetation type.

scholarly journals Effects of vegetation change on evapotranspiration in a semiarid shrubland of the Loess Plateau, China

2014 ◽  
Vol 11 (12) ◽  
pp. 13571-13605 ◽  
Author(s):  
T. T. Gong ◽  
H. M. Lei ◽  
D. W. Yang ◽  
Y. Jiao ◽  
H. B. Yang
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Loess Plateau ◽  
Vegetation Change ◽  
Hydrological Cycle ◽  
Bare Soil ◽  
Observation Data ◽  
The Loess Plateau ◽  
Soil Desiccation ◽  
The North

Abstract. Vegetation change is a primary factor that affect evapotranspiration (ET), which is an important process in the hydrological cycle. In this study, an attempt is made to analyze the effects of vegetation change on ET using continuous observation data from eddy-covariance (EC) measurements over three periods (1 July 2011 to 30 June 2014) of a study site in a sparse shrubland study site located in the Loess Plateau of China, which is a fragile ecosystem experiencing serious soil desiccation. In our study, vegetation change includes phenological change and land use change. Phenological process of vegetation is validated to have a remarkable positive effect on ET in a rate of 1.83 ± 0.01 along with vegetation greening. Land use change at our study site was due to the native vegetation being cut-off by human activities, converting sparse shrubland to bare soil. With land use condition changing during the three years, annual total ET was observed to increase 103 mm, suggesting that soil evaporation consumes more water than canopy transpiration. In summary, the effects of vegetation change on ET suggest that both vegetation greening and increased area of exposed soil would aggravate the soil desiccation at our site in the north Loess Plateau.

Climate and land use change impacts on water resources in Sardinia (Italy)

2021 ◽  
Author(s):  
Dario Ruggiu ◽  
Salvatore Urru ◽  
Roberto Deidda ◽  
Francesco Viola
Keyword(s):  
Land Use ◽  
Water Resources ◽  
Land Use Change ◽  
Hydrological Cycle ◽  
Potential Evapotranspiration ◽  
Regional Scale ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Land Use Scenarios ◽  
Near Future

<p>The assessment of climate change and land use modifications effects on hydrological cycle is challenging. We propose an approach based on Budyko theory to investigate the relative importance of natural and anthropogenic drivers on water resources availability. As an example of application, the proposed approach is implemented in the island of Sardinia (Italy), which is affected by important processes of both climate and land use modifications. In details, the proposed methodology assumes the Fu’s equation to describe the mechanisms of water partitioning at regional scale and uses the probability distributions of annual runoff (Q) in a closed form. The latter is parametrized by considering simple long-term climatic info (namely first orders statistics of annual rainfall and potential evapotranspiration) and land use properties of basins.</p><p>In order to investigate the possible near future water availability of Sardinia, several climate and land use scenarios have been considered, referring to 2006-2050 and 2051-2100 periods. Climate scenarios have been generated considering fourteen bias corrected outputs of climatic models from EUROCORDEX’s project (RCP 8.5), while three land use scenarios have been created following the last century tendencies.</p><p>Results show that the distribution of annual runoff in Sardinia could be significantly affected by both climate and land use change. The near future distribution of Q generally displayed a decrease in mean and variance compared to the baseline.   </p><p>The reduction of  Q is more critical moving from 2006-2050 to 2051-2100 period, according with climatic trends, namely due to the reduction of annual rainfall and the increase of potential evapotranspiration. The effect of LU change on Q distribution is weaker than the climatic one, but not negligible.</p>

scholarly journals Hydro-climatic and land use/cover changes in Nasia catchment of the White Volta basin in Ghana

2021 ◽  
Author(s):  
Emmanuel Nyadzi ◽  
Enoch Bessah ◽  
Gordana Kranjac-Berisavljevic ◽  
Fulco Ludwig
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Water Resources ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Potential Evapotranspiration ◽  
Sunshine Duration ◽  
Climatic Variables ◽  
Northern Ghana ◽  
Maximum Temperature

AbstractThe Nasia catchment is the reservoir with significant surface water resources in Northern Ghana and home to numerous subsistence farmers engaged in rainfed and dry season irrigation farming. Yet, there is little understanding of the hydro-climatic and land use/cover conditions of this basin. This study investigated trends, relationships and changes in hydro-climatic variables and land use/cover in addition to implications of the observable changes in the Nasia catchment over a period of 50 years. Parameters used for the study were minimum (Tmin) and maximum temperature (Tmax), wind speed (WS), sunshine duration (S), rainfall (R), relative humidity (RH), discharge (D) and potential evapotranspiration (PET) data, 15 years of remotely sensed normalized difference vegetation index (NDVI) data and 30 years of land use/cover image data. Results show that Tmin, Tmax, WS and PET have increased significantly (p < 0.05) over time. RH and S significantly declined. R, D and NDVI have not decreased significantly (p > 0.05). A significant abrupt change in almost all hydro-climatic variables started in the 1980s, a period that coincides with the occurrence of drought events in the region, except WS in 2001, R in 1968 and D in 1975, respectively. Also, D showed a positive significant correlation with RH, R and PET, but an insignificant positive relationship with S. D also showed a negative insignificant correlation with Tmin, Tmax and WS. Areas covered with shrubland and settlement/bare lands have increased to the disadvantage of cropland, forest, grassland and water bodies. It was concluded that climate change impact is quite noticeable in the basin, indicating water scarcity and possibilities of droughts. The analysis performed herein is a vital foundation for further studies to simulate and predict the effect of climate change on the water resources, agriculture and livelihoods in the Nasia catchment.

scholarly journals Impacts of the Tropical Cyclone Idai in Mozambique: A Multi-Temporal Landsat Satellite Imagery Analysis

2021 ◽  
Vol 13 (2) ◽  
pp. 201
Author(s):  
Alberto Bento Charrua ◽  
Rajchandar Padmanaban ◽  
Pedro Cabral ◽  
Salomão Bandeira ◽  
Maria M. Romeiras
Keyword(s):  
Land Use ◽  
Tropical Cyclone ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Pearson Correlation ◽  
Natural Habitats ◽  
Abrupt Decrease ◽  
Barren Land ◽  
Climate Hazards ◽  
Landsat Satellite

The Central Region of Mozambique (Sofala Province) bordering on the active cyclone area of the southwestern Indian Ocean has been particularly affected by climate hazards. The Cyclone Idai, which hit the region in March 2019 with strong winds causing extensive flooding and a massive loss of life, was the strongest recorded tropical cyclone in the Southern Hemisphere. The aim of this study was to use pre- and post-cyclone Idai Landsat satellite images to analyze temporal changes in Land Use and Land Cover (LULC) across the Sofala Province. Specifically, we aimed—(i) to quantify and map the changes in LULC between 2012 and 2019; (ii) to investigate the correlation between the distance to Idai’s trajectory and the degree of vegetation damage, and (iii) to determine the damage caused by Idai on different LULC. We used Landsat 7 and 8 images (with 30 m resolution) taken during the month of April for the 8-year period. The April Average Normalized Difference Vegetation Index (NDVI) over the aforementioned period (2012–2018, pre-cyclone) was compared with the values of April 2019 (post-cyclone). The results showed a decreasing trend of the productivity (NDVI 0.5 to 0.8) and an abrupt decrease after the cyclone. The most devastated land use classes were dense vegetation (decreased by 59%), followed by wetland vegetation (−57%) and shrub land (−56%). The least damaged areas were barren land (−23%), barren vegetation (−27%), and grassland and dambos (−27%). The Northeastern, Central and Southern regions of Sofala were the most devastated areas. The Pearson Correlation Coefficient between the relative vegetation change activity after Idai (NDVI%) and the distance to Idai’s trajectory was 0.95 (R-square 0.91), suggesting a strong positive linear correlation. Our study also indicated that the LULC type (vegetation physiognomy) might have influenced the degree of LULC damage. This study provides new insights for the management and conservation of natural habitats threatened by climate hazards and human factors and might accelerate ongoing recovery processes in the Sofala Province.

scholarly journals Mapping Evapotranspiration of Agricultural Areas in Ghana

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Kenneth Aidoo ◽  
Nana Ama Browne Klutse ◽  
Kofi Asare ◽  
Comfort Gyasiwaa Botchway ◽  
Samuel Fosuhene
Keyword(s):  
Land Use ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Environmental Changes ◽  
Hydrological Cycle ◽  
Remotely Sensed Data ◽  
Spatial Dimensions ◽  
Combined Estimation ◽  
Annual Water ◽  
Agricultural Areas

Climate change is having an adverse effect on the environment especially in sub-Sahara Africa, where capacity for natural resource management such as water is very low. The scope of the effect on land use types have to be estimated to inform proper remedy. A combined estimation of transpiration and evaporation from plants and soil is critical to determine annual water requirement for different land use. Evapotranspiration (ET) is a major component in the world hydrological cycle, and understanding its spatial dimensions is critical in evaluating the effects it has on regional land use. A measure of this component is challenging due to variation in rainfall and environmental changes. The mapping evapotranspiration with high resolution and internalized calibration (METRIC) method is employed to create evapotranspiration map for land use, using remotely sensed data by satellite, processed, and analyzed in ArcGIS. Normalized difference vegetation index (NDVI) was related to the availability of water for vegetation on different land use, and the results indicate a high evapotranspiration for vegetated land use with high NDVI than land use with low NDVI.

scholarly journals Estimating Evapotranspiration in a Post-Fire Environment Using Remote Sensing and Machine Learning

2018 ◽  
Vol 10 (11) ◽  
pp. 1728 ◽  
Author(s):  
Patrick Poon ◽  
Alicia Kinoshita
Keyword(s):  
Machine Learning ◽  
Land Surface ◽  
Vegetation Index ◽  
Hydrological Cycle ◽  
Potential Evapotranspiration ◽  
Remotely Sensed ◽  
Support Vector ◽  
Moisture Index ◽  
Input Variables ◽  
Normalized Burn Ratio

In the hydrological cycle, evapotranspiration (ET) transfers moisture from the land surface to the atmosphere and is sensitive to disturbances such as wildfires. Ground-based pre- and post-fire measurements of ET are often unavailable, limiting the potential to understand the extent of wildfire impacts on the hydrological cycle. This research estimated both pre- and post-fire ET using remotely sensed variables and support vector machine (SVM) methods. Input variables (land surface temperature, modified soil-adjusted vegetation index, normalized difference moisture index, normalized burn ratio, precipitation, potential evapotranspiration, albedo and vegetation types) were used to train and develop 56 combinations that yielded 33 unique SVM models to predict actual ET. The models were trained to predict a spatial ET, the Operational Simplified Surface Energy Balance (SSEBop), for the 2003 Coyote Fire in San Diego, California (USA). The optimal SVM model, SVM-ET6, required six input variables and predicted ET for fifteen years with a root-mean-square error (RMSE) of 8.43 mm/month and a R2 of 0.89. The developed model was transferred and applied to the 2003 Old Fire in San Bernardino, California (USA), where a watershed balance approach was used to validate SVM-ET6 predictions. The annual water balance for ten out of fifteen years was within ±20% of the predicted values. This work demonstrated machine learning as a viable method to create a remotely-sensed estimate with wide applicability for regions with sparse data observations and information. This innovative work demonstrated the potential benefit for land and forest managers to understand and analyze the hydrological cycle of watersheds that experience acute disturbances based on this developed predictive ET model.

scholarly journals Hydro-climatic and Land use/cover Changes in Nasia Catchment of the White Volta Basin in Ghana

2021 ◽  
Author(s):  
Emmanuel Nyadzi ◽  
Enoch Bessah ◽  
Gordana Kranjac-Berisavljevic ◽  
Fulco Ludwig
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Water Resources ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Potential Evapotranspiration ◽  
Sunshine Duration ◽  
Image Data ◽  
Northern Ghana ◽  
Maximum Temperature

Abstract The Nasia catchment is the reservoir for significant surface water resources in Northern Ghana and home to numerous subsistence farmers engaged in rainfed and dry season irrigation farming. Yet there is little understanding of the hydro-climatic and land use /cover conditions of this basin. We analyzed 50 years of minimum (Tmin) and maximum temperature (Tmax), wind speed (WS), sunshine duration(S), Rainfall(R), relative humidity (RH), discharge (D) and potential evapotranspiration (PET) data, 15 years of remotely sensed normalized difference vegetation index (NDVI) data and 30 years of land use/cover image data. Results show that Tmin, Tmax, WS, and PET have increased significantly (P < 0.05). RH and S significantly declined. R, D and NDVI have insignificantly decreased (P > 0.05). A significant abrupt change in almost all hydroclimatic variables started in the 1980s, a period that coincides with the occurrence of drought events in the region except WS in 2001, R in 1968 and D in 1975. Also, D showed a positive significant correlation with RH, R and PET, but insignificant positive relationship with S. D also showed negative insignificant correlation with Tmin, Tmax and WS. Areas covered with shrubland and settlement/bare lands have increased to the disadvantage of cropland, forest, grassland and water bodies. We conclude that climate change impact is quite noticeable in the basin; indicating water scarcity and possibilities of droughts. The analysis performed herein is a vital foundation for further studies to simulate and predict the effect of climate change on the water resources, agriculture and livelihood in the Nasia basin.

Analysis of Land Use Land Cover in Annapurna Conservation Area in Gandaki Province, Nepal using Vegetation Index and Land Use Land Cover Datasets

2019 ◽  
Vol 2 (2) ◽  
pp. 87-99
Author(s):  
Shiva Pokhrel ◽  
Chungla Sherpa
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Vegetation Index ◽  
National Level ◽  
Climate Mitigation ◽  
Land Use Land Cover ◽  
Conservation Area ◽  
Barren Land ◽  
Wide Range ◽  
Annapurna Conservation Area

Conservation areas are originally well-known for protecting landscape features and wildlife. They are playing key role in conserving and providing a wide range of ecosystem services, social, economic and cultural benefits as well as vital places for climate mitigation and adaptation. We have analyzed decadal changes in land cover and status of vegetation cover in the conservation area using both national level available data on land use land cover (LULC) changes (1990-2010) and normalized difference vegetation index (NDVI) (2010-2018) in Annapurna conservation area. LULC showed the barren land as the most dominant land cover types in all three different time series 1990, 2000 and 2010 with followed by snow cover, grassland, forest, agriculture and water body. The highest NDVI values were observed at Southern, Southwestern and Southeastern part of conservation area consisting of forest area, shrub land and grassland while toward low to negative in the upper middle to the Northern part of the conservation area.

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