scholarly journals Development of Desertification Indicators for Desertification Monitoring from Landsat Images Using Python Programming

2022 ◽  
Vol 8 (2) ◽  
pp. 99-114
Author(s):  
Lamyaa Gamal EL-Deen Taha ◽  
Manar A. Basheer ◽  
Amany Morsi Mohamed
Keyword(s):  
Sand Dune ◽  
Sand Dunes ◽  
Landsat Images ◽  
Image Differencing ◽  
Layer Stacking ◽  
Southern Side ◽  
Sand Movement ◽  
Dune Migration ◽  
Desertification Assessment ◽  
Python Programming

Nowadays, desertification is one of the most serious environment socioeconomic issues and sand dune advances are a major threat that causes desertification. Wadi El-Rayan is one of the areas facing severe dune migration. Therefore, it's important to monitor desertification and study sand dune migration in this area. Image differencing for the years 2000 (Landsat ETM+) and 2019 (OLI images) and Bi-temporal layer stacking was performed. It was found that image differencing is a superior method to get changes of the study area compared to the visual method (Bi-temporal layer stacking). This research develops a quantitative technique for desertification assessment by developing indicators using Landsat images. Spatial distribution of the movement of sand dunes using some spectral indices (NDVI, BSI, LDI, and LST) was studied and a Python script was developed to calculate these indices. The results show that NDVI and BSI indices are the best indices in the identification and detection of vegetation. It was found that mobile sand dunes on the southern side of the lower Wadi El-Rayan Lake caused filling up of large part of the lower lake. The indices results show that sand movement decreased the size of the lower Wadi El-Rayan Lake and there are reclamation activities in the west of the lower lake. The results show that a good result could be achieved from the developed codes compared to ready-made software (ENVI 5).

Seedling desiccation tolerance of Leymus racemosus (Poaceae) (wild rye), a perennial sand-dune grass inhabiting the Junggar Basin of Xinjiang, China

2004 ◽  
Vol 14 (2) ◽  
pp. 233-239 ◽  
Author(s):  
Zhenying Huang ◽  
Yitzchak Gutterman
Keyword(s):  
Desiccation Tolerance ◽  
Sand Dune ◽  
Sand Dunes ◽  
Perennial Grass ◽  
Junggar Basin ◽  
Seedling Development ◽  
Ecological Implications ◽  
Leymus Racemosus ◽  
Seedling Desiccation Tolerance ◽  
Dune Grass

Leymus Racemosus, The Mammoth Wild Rye, Is A Rhizomatous Perennial Grass, Mainly Distributed In The Moving Or Semi-Stabilized Sand Dunes In Deserts Of The Junggar Basin In Xinjiang, China. The Revival Ability Of The Young Seedling After Periods Of Desiccation Can Be Influenced By Several Factors: (1) The Stage Of Seedling Development – The Later The Stage At Dehydration, The Longer The Root Length And The Lower Is The Percentage Of Seedlings That Survive; (2) The Length Of The Period Of Desiccation – The Longer The Period That The Seedlings Are Under Desiccation, The Lower Is The Percentage Of Seedlings That Survive; (3) Endosperm Size – The Smaller The Proportion Of Endosperm That Remains In The Caryopses, The Lower Is The Percentage Of Seedlings That Revive, Determined By (A) The Stage Of Seedling Development, And (B) The Proportion Of The Endosperm That Is Removed By Cutting; And (4) Caryopsis Size – The Larger The Polymorphic Caryopses, The Higher Is The Percentage Of Young Seedlings That Revive From Periods Of Desiccation. The Physiological And Ecological Implications Of L. Racemosus Seedling Desiccation Tolerance Are That Under Extreme Desert And Unpredictable Environmental Conditions, The Chances Of Seedling Establishment Are Increased.

Leaf demography and decline of Panicum racemosum populations in coastal foredunes of southern Brazil

1991 ◽  
Vol 69 (7) ◽  
pp. 1593-1599 ◽  
Author(s):  
César S. B. Costa ◽  
Ulrich Seeliger ◽  
César V. Cordazzo
Keyword(s):  
Population Biology ◽  
Sand Dunes ◽  
Salt Spray ◽  
Nutrient Status ◽  
Southern Brazil ◽  
Leaf Demography ◽  
Growth Vigour ◽  
Sand Movement ◽  
Mobile Dune ◽  
Sand Deposition

We studied the effect of nutrient status and sand movement on the population biology of Panicum racemosum Spreng. over a 5-year period (1982–1986) on mobile, semifixed and fixed coastal foredune habitats in southern Brazil. The soils were deficient in nitrate, phosphate, and potassium (<0.5, 0.2–1.2, and 3–5 mg/kg, respectively) in all habitats, and a gradient of decreasing availability existed from the mobile to the fixed dunes. Half-lives of leaves were shorter in the fixed dune as compared with the mobile dune. Similarly, half-lives of leaves were shorter in summer than in winter. Experiments using cuttings of P. racemosum tillers showed that as P. racemosum plants grew, so did the deposition of sand on mobile foredunes. The mechanical deposition of sand itself did not stimulate P. racemosum growth. The deposition of saline sand provided a substrate that supported vertical growth of P. racemosum rhizomes and tillers and was a source of adsorbed nutrients. Also, active sand deposition limited the invasion of frontal dunes by other species. Panicum racemosum populations changed from "invader" to "mature" to "regressive" age states over a 5-year period, apparently in response to the spatial patterns of sand deposition and salt spray input. Key words: Panicum, leaf demography, growth vigour, sand dunes, temporal changes.

Allelopathic potential of Artemisia campestris ssp. caudata on Lake Huron sand dunes

1997 ◽  
Vol 75 (11) ◽  
pp. 1903-1912 ◽  
Author(s):  
Kyeong W. Yun ◽  
M. A. Maun
Keyword(s):  
Seed Germination ◽  
Seedling Growth ◽  
Mycorrhizal Fungi ◽  
Sand Dune ◽  
Sand Dunes ◽  
Dry Weight ◽  
Fungal Colonization ◽  
Test Species ◽  
Allelopathic Potential ◽  
Artemisia Campestris

Greenhouse studies were conducted to test allelopathic effects of Artemisia campestris ssp. caudata on seed germination and seedling growth of several sand-dune species and colonization by mycorrhizal fungi. The aqueous extracts of A. campestris showed no inhibitory effect on seed germination, seedling elongation, or dry-weight growth of plants at lower concentrations (10 and 50%), but 100% concentration of the extracts caused varying degrees of inhibition depending on the test species. The mixing of dry leaves of seedlings of A. campestris to the sand showed severe inhibition of Elymus canadensis seedlings. The percent germination of test species in soil from the rhizosphere of A. campestris was significantly lower than that of the control. The leaf area and dry weight were also lower but the differences were not significant. The aqueous extract inhibited mycorrhizal fungal colonization in roots of three sand-dune grasses. Key words: allelopathy, Artemisia campestris ssp. caudata, seed germination, seedling growth, mycorrhizal fungi.

scholarly journals A Study of Desertification Using Remote Sensing Techniques in Basra Governorate, South Iraq

2021 ◽  
pp. 912-926
Author(s):  
Fadel Abbas Zwain ◽  
Thair Thamer Al-Samarrai ◽  
Younus I. Al-Saady
Keyword(s):  
Remote Sensing ◽  
Land Degradation ◽  
Land Surface ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Arid Zone ◽  
Sand Dunes ◽  
Risk Index ◽  
Anthropogenic Factors ◽  
Landsat Images

Iraq territory as a whole and south of Iraq in particular encountered rapid desertification and signs of severe land degradation in the last decades. Both natural and anthropogenic factors are responsible for the extent of desertification. Remote sensing data and image analysis tools were employed to identify, detect, and monitor desertification in Basra governorate. Different remote sensing indicators and image indices were applied in order to better identify the desertification development in the study area, including the Normalized difference vegetation index (NDVI), Normalized Difference Water Index (NDWI), Salinity index (SI), Top Soil Grain Size Index (GSI) , Land Surface Temperature (LST) , Land Surface Soil Moisture (LSM), and Land Degradation Risk Index (LDI) which was used for the assessment of degradation severity .Three Landsat images, acquired in 1973, 1993, and 2013, were used to evaluate the potential of using remote sensing analysis in desertification monitoring. The approach applied in this study for evaluating this phenomenon was proven to be an effective tool for the recognition of areas at risk of desertification. The results indicated that the arid zone of Basra governorate encounters substantial changes in the environment, such as decreasing surface water, degradation of agricultural lands (as palm orchards and crops), and deterioration of marshlands. Additional changes include increased salinization with the creeping of sand dunes to agricultural areas, as well as the impacts of oil fields and other facilities.

scholarly journals Modelling and  assessing driving factors of the spatial and temporal dynamics of the sand  dunes in the district of Errachidia, Morocco

2021 ◽  
Author(s):  
Tudal SINSIN ◽  
Fouad MOUNIR ◽  
Ahmed El ABOUDI
Keyword(s):  
Sand Dune ◽  
Temporal Dynamics ◽  
Moving Average ◽  
Sand Dunes ◽  
Ecological Factors ◽  
Temperature And Precipitation ◽  
Spatial And Temporal Dynamics ◽  
Combined Action ◽  
Landsat Satellite ◽  
Dune Dynamics

The desertification affects more than 250,000 ha in the district of Errachidia and results in the expansion of desert landscapes such as the Regs, Hamadas and the Dunes. The latter is a big concern in the district since it is the source of siltation, which threatens dwellings, cultivated lands and water bodies. It is of paramount importance to understand the causes and consequences of silting to develop strategies to combat it. Thus, first, we analysed the spatial and temporal dynamics of sand dunes until 2069 by applying the Seasonal Autoregressive Integrated Moving-Average (SARIMA) model on a time series of sand dune areas. These areas were calculated annually from 1987 to 2019 by computing the sand cover index (SCI) on Landsat satellite images. Furthermore, we evaluated the influence of different natural and human factors such as temperature, precipitation, wind, vegetation, and population growth, on sand dune dynamics using Spearman’s correlation test. The results indicated that the area of sand dunes will increase by 1.7% per year between 2019 and 2069 in the district of Errachidia. This increase would be mainly caused by the combined action of ecological factors, which vary from year to year. In general, temperature and precipitation act indirectly on wind and vegetation to influence the dynamics of sand dunes in hyper-arid areas where the soil is bare or poorly covered with vegetation, where precipitation is low and where temperature is high.

scholarly journals The Sources of Moisture in the Sand Dunes – The Example of the Western Sahara Dune Field

2014 ◽  
Vol 33 (3) ◽  
pp. 199-204 ◽  
Author(s):  
Elwira Żmudzka ◽  
Dariusz Woronko ◽  
Maciej Dłużewski
Keyword(s):  
Surface Layer ◽  
Moisture Content ◽  
Wind Velocity ◽  
Sand Dune ◽  
Sand Dunes ◽  
Shear Velocity ◽  
Meteorological Conditions ◽  
Aeolian Transport ◽  
Western Sahara ◽  
Dune Field

Abstract Climatic and meteorological conditions may limit the aeolian transport within barchans. An explanation of that issue was the main goal of the investigation held in Western Sahara dune fields located around Tarfaya and Laâyoune. Particular attention was paid to the factors causing the moisture content rising of the sand dune surface layer, which could influence the wind threshold shear velocity in the aeolian transport. The wetted surface layer of sand, when receiving moisture from precipitation or suspensions, reduces the aeolian transport, even in case of wind velocity above 4-5 m s-1. Fog and dew condensation does not affect the moisture of deeper sand layers, what occurs after rainfall.

Sand Dune Migration Monitoring for Pipeline Hazard Risk Mitigation: The Peru LNG Coastal Section Case

2020 ◽  
Author(s):  
Fabien Ravet ◽  
Christian Silva ◽  
Rodolfo Gil ◽  
Simon Maguire ◽  
Etienne Rochat
Keyword(s):  
Early Detection ◽  
Natural Hazards ◽  
Sand Dune ◽  
Fiber Optic ◽  
Risk Mitigation ◽  
Third Party ◽  
Transport Systems ◽  
Geotechnical Monitoring ◽  
Dune Migration ◽  
Hydrocarbon Transport

Abstract Pipelines often cross challenging terrains where natural hazards are the main risk for their integrity. Environmental conditions can also worsen over the infrastructure lifetime. To reduce the risk of disasters, integrity programs are developed implementing tools for early detection of threats that can lead to a failure with dramatic social, environmental and economic consequences. Fiber optic (FO) monitoring solutions have been widely used and implemented as one of the most efficient prevention tools of these programs. These solutions include geotechnical monitoring, third party intrusion detection and eventually small or pinhole like leak detection. FO based geotechnical monitoring has been successfully operated along the Sierra section of the Peru LNG pipeline since 2010, detecting minor landslides and erosion events. It has also been implemented along other hydrocarbon transport systems to allow the early detection of such events. However, these natural hazards are not the only ones threatening the pipeline. In fact, the coastal section experiences other phenomenon such as sand dune migration and eolian erosion that put the pipeline at risk. Recently, the FO monitoring was extended to the coastal region using the existing communication fiber optic cable to sense temperature changes. Very localized events are thermally detected, their spatial and temporal signature analyzed. The comparison of this data with thermal models identified sections that are close to be exposed or whose soil cover is less than 50cm over a spatial extension that does not exceed a couple of meters. Depth of cover of 10 to 30cm is estimated from such analysis. These results are confirmed by past and ongoing site inspections. Such positive results again illustrate the potential value of fiber optic sensing to mitigate geohazard risks. It not only enhances the efficiency of the integrity program detecting and localizing threats, it also improves and rationalizes the maintenance activities as focused surveys can be conducted.

Ecological aspects influencing the helminth community of the wood mouse Apodemus sylvaticus in Dunas de Mira, Portugal

2006 ◽  
Vol 51 (4) ◽  
Author(s):  
Catarina Eira ◽  
Jordi Torres ◽  
José Vingada ◽  
Jordi Miquel
Keyword(s):  
Species Richness ◽  
Sand Dune ◽  
Sand Dunes ◽  
Wood Mouse ◽  
Apodemus Sylvaticus ◽  
Habitat Characteristics ◽  
Helminth Community ◽  
Heligmosomoides Polygyrus ◽  
Ecological Aspects ◽  
Host Sex

AbstractThis paper presents the first extensive data on the helminth community of the wood mouse Apodemus sylvaticus in a coastal sand dune area in Portugal. The 557 hosts analysed in this study were trapped seasonally between autumn 2002 and summer 2005 across 6 habitat types. Twelve helminth species were detected among which, Taenia parva larvae, Angiostrongylus dujardini, Heligmosomoides polygyrus, Syphacia stroma and S. frederici constitute the component species, accounting for 98.7% of all worms. H. polygyrus was the most prevalent helminth parasite. Species richness varied according to habitat and season. The highest species richness was found in sand dunes during winter whereas the lowest was detected along lake margins also during the winter. Some differences in prevalence and mean intensity values were found in relation to year (T. parva larvae and H. polygyrus), habitat (A. dujardini), season (T. parva larvae, H. polygyrus, A. dujardini and S. stroma) and host sex (T. parva larvae and S. stroma). These differences are discussed both in view of the host’s biology and habitat characteristics.

scholarly journals Integrated Geological, Hydrogeological, and Geophysical Investigations of a Barchan Sand Dune in the Eastern Region of Saudi Arabia

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 682
Author(s):  
Mohammed Benaafi ◽  
Sherif M. Hanafy ◽  
Abdullatif Al-Shuhail ◽  
Ammar El-Husseiny ◽  
Jack Dvorkin
Keyword(s):  
Grain Size ◽  
Saudi Arabia ◽  
Water Content ◽  
Sand Dune ◽  
Sand Dunes ◽  
Homogeneous Medium ◽  
Eastern Region ◽  
Large Area ◽  
Electrical Resistivity Survey ◽  
Dune Crest

In arid countries such as Saudi Arabia, aeolian sand often covers a large area of the country. Understanding the variations of sand properties in dunes, including grain size, sorting, mineral composition and water content, can be important for groundwater recharge, environmental, and construction applications. Earlier studies examined properties of sand dunes by collecting samples from the surface. This study aims to investigate variations of sand properties within a Barchan sand dune in the coastal area of Saudi Arabia, by collecting samples and measurements from two vertically drilled boreholes up to the ground water level; one drilled in the dune crest and another one in the limb. Representative samples were collected and analyzed for their texture parameters, water content, and mineralogy. Electrical resistivity survey data was also acquired to map water content variation in the dune limb, and for comparison with well bore data. The reported results show no vertical variations in grain size or sorting in the dune crest. In contrast, the upper 0.5 m of the dune limb shows a relatively poorer sorting than found in deeper parts of the dune. Laterally, no variations in minerology were observed between crest and limb sands while grain size tended to be slightly coarser in the dune limb compared to the crest. Regarding the water content, it was found to vary vertically, probably due to previous cycles of rainfall infiltration through the sand body. Such observed variation in water content is consistent with the measured resistivity profile which could clearly identify the water table and areas with higher water content. This study concludes that beyond the upper 0.5 m, the Barchan sand dune body can be treated as a homogeneous medium in terms of mineralogy and sorting while grain size increases slightly toward the limb side.

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