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Accueil du site → Doctorat → Egypte → EFFECT OF LAND DEGRADATION ON LAND COVER ATTRIBUTES OF EAST SUEZ CANAL USING REMOTE SENSING TECHNIQUES

Ain Shams University (2017)

EFFECT OF LAND DEGRADATION ON LAND COVER ATTRIBUTES OF EAST SUEZ CANAL USING REMOTE SENSING TECHNIQUES

AFIFY, NAGWAN MAHMOUD MAHMOUD

Titre : EFFECT OF LAND DEGRADATION ON LAND COVER ATTRIBUTES OF EAST SUEZ CANAL USING REMOTE SENSING TECHNIQUES

Auteur : AFIFY, NAGWAN MAHMOUD MAHMOUD.

Etablissement de soutenance : Ain Shams University

Grade : Doctor of Philosophy (PhD) in Agricultural Science (Agriculture in desert and salt affected areas) 2017

Résumé
The main objectives of this study are to produce a land cover map for an area east of Suez Canal in order to assess the level of land degradation as aftermath of the exiting informal irrigation practices dominated in the area. Also to predict the deterioration magnitude in the study area on the long runs with the same informal practices. Confirming a collective master index to measure the spectral signatures of different land cover classes was a significant target. The current study elements and findings are summarized as follows : 5.1 Methodological approach and methods : In this study, for getting more accurate mapping results, Hyperion (EO-1) and multispectral (TM8) remote sensing data acquired in January 2016 were used. Ground truth was performed to check the boundaries of mapping units and to study their soil attributes. Fifteen soil profiles were morphologically described and sampled for laboratory analyses. These analyses were carried out for measuring particle size distribution and calcium carbonate content. Soil pH and salinity were measured in the saturated soil past extract. Soil profiles were classified according to Soil Taxonomy of USDA (20140), while land cover classes were categorized according to the Land Cover Classification System (2004). 5.2 The current status of land unit features The cultivated land in the study area is practically managed under surface irrigation system. The irrigation water is vertically draining within sandy strata of the cultivated seeped eastwards and south eastwards. This mechanism can be illustrated from the Digital Elevation Model (DEM)) as the water seepage creates spots of submerged areas and waterlogged ones. Land cover classes include mango trees, annual crops mainly clover and mixed areas of different life forms. Bare areas are stony soils, shifting sands and waterlogged areas of submerged ones. The artificial surfaces are urban and main roads. 5.3 Validity Assessment of NDVI from Hyperion Data to Scan Multiple Surface Types. Pearson’s correlation coefficients indicated that NDVI is highly correlated to NDWI, NDMI and NDSI as the correlation coefficient magnitudes are 0.95, 0.75 and 0.82 respectively. They are all above the value of 0.7 (highly correlated variables). Accordingly, NDVI index can be considered as a master index that can be used for well identification of the multiple land cover features and their distributions. On the other hand variable NDVI extracted from Hyperion data is highly correlated with that of NDVI extracted from TM8 data. (above 0.7) concerning the land cover of vegetated areas , bare areas of shifting sands and submerged areas The correlation is moderate concerning the bare area of stony soils and water logged areas. 5.4 Change Detection of Land Cover Distributions in the Study Area land cover classes were assessed by sorting NDVIvalues extracted fromTM5, 7 and 8 data for the years 1988, 2001 and 2016 respectively. Land cover classes were defined in the three periods. During the period from 1988 to 2016 cultivated land increased by 20981 hectare (ha). Bare area (stony soils) decreased during the same period from 49693 to 23633 hectares. Bare areas (shifting sands) also decrease by 1463 ha, while urban area increased by 316 ha. Waterlogged area increased from 1176 to 5204 ha during the same period as well as submerged area increased by 1181 ha. This land cover class includes the artificial lakes of Great Bitter Lake and El- Temsah one it also includes Suez Canal covering 22562, 22562 and 23578 ha for the years 1988, 2001 and 2016 respectively. 5.5 Predictable Extension of Land Deterioration in the Study Area The study area will be negatively affected by long-term of using surface irrigation on sandy soils. By analyzing slope gradients, the contour line of 30 meters above sea level is considered as the line of break slope. Following the slope gradient classes of FOA (2006) this line separates the slope gradient of nearly level areas (0.4 to 1.0 %) westwards from those of gently sloping to sloping areas (2.5 to 5.0 %) east of that contour line. The detectable extension of the land degradation based on tracing the contour line at elevation 30 meter above sea for delineating an area is descending westwards. This area will be most probably affected by the seepage of drained water to spread over 35303 ha. Partly, the deterioration will cover about 10997 ha of the cultivated land, while the bare areas of the stony soils may be negatively affected in area of 14055 ha

Présentation étendue (EULC)

Page publiée le 11 février 2019