The main aim of this study was to assess and mapping of land cover (LC) / land use (LU), using Remote Sensing (RS) and Geographical Information System (GIS) techniques in Elnor natural forest reserve, Blue Nile state, Sudan. The study also attempted to update some information in the study area such as LC and contour map by using different methods of data transformation and analysis such as Normalized Different Vegetation Index (NDVI), interpolation and supervised classification. Thematic Mapper (TM), Landsat Enhanced Thematic Mapper (ETM+) and Landsat8 images were used in LCLU changes and supported by field observation. The study area was affected by cutting the mother trees and overgrazing. Closed forests during 2000, 2010 and 2019 decreased from 36.9%, 28.5% and 18.7% respectively. Moreover, the total area of bare soil increased by about 14.4%, 47.2% and 39.7% in 2000, 2010 and 2019 respectively. The open forest (grassland) decreased from 48.7% in (2000) to 41.7% in (2019). A Digital land cover map was produced using LCCS software; depending on the fieldwork data, they were found in four Classes. Mixed Woodland Single Layer, Semi-Deciduous Shrub land with Open Herbaceous, Open Grassland, Single XII Layer and Hardpans. The study revealed that there are some indicators of land degradation during the last 20 years (2000, 2010 and 2019) and is expected to continue increasing unless serious measures are carried out to reduce it.
Wind erosion and salt–affected soils are predominant desertification processes in Sudan, particularly in the northern part, and have adverse impacts on agricultural lands in the arid and semi-arid lands characterized by erratic rainfall, high temperature, high wind velocity and consequent high rates of evapotranspiration. The main objective of this paper is to present research review on combating, control, reclamation and management practices in areas affected by wind erosion and salt–affected soils. The study showed that the principal measures for controlling wind erosion depends on minimizing certain conditions that can be accelerated wind erosivity (winds ≥ 5.4 m/sec) and vice versa maximizing soil erodibility by creation a suitable condition for generate of non–erodible soil particles (NEP) versus soil surface detachment and transport by wind. Wind erosion research requires high financial support, thus this cost should be borne by government. The strategy of management practices of saltaffected soils aimed to sustain a level of salinity tolerable to the cultivated crops through good manages to water and crop. Assessment and mapping of wind erosion and salt-affected soils is urgent need to determine the inherent risk in the affected areas included in investment map of agricultural land capabilities of the country. Encourage studies on stabilizing soil particles by various natural or synthetic cementing and flocculation materials which are friendly to soil environment to increase NEP on the soil surface. Practical programs on reclamation of salt–affected soils should be included in national development programs and national strategy for scientific research in the State.
This study was conducted in the Wahat Elnukhila area, about 600 km northeast of El-fashier town, northern Darfur State, to produce broad–base data on the geographical distribution of soils, characterization of soils using some soil indicators (ECe, pH and SAR), explore the natural land cover and evaluate the soil suitability for agricultural activities in the study area. The study area covers (20000 feddans). This research was based on the data and information extracted from the soil survey, remote sensed landsat, Enhanced Thematic Mapper (ETM+) images dated 2018, in addition to field observation aided by GPS receivers and geographic information system were used to generate soil map in the study area. By using the American soil classification system (FAO, 1990 and 2006) study area may be classified into three units, the total area of the three units and natural vegetation cover decreased in the following order: unit1 (12734 feddans) > unit 2 (3994 feddans) > unit 3 (3272 feddans), green covers as a result of the availability of quantities of ground and surface water, which distinguishes it from the rest of the surrounding desert lands. The predominant vegetation cover is Imperata cylindrica (halfa), Tamarix (Tarfa), phragmites (communist)“ Alboes”, Citrullus Colocynthis (Hanzal), Ischaemum muticum and p. dactylifera (date palm). Regarding soil texture, drainage, soil depth, and fertility status for units 1, unit 2, and unit 3, can be described as follows: sandy to loamy sand, well-drained, shallow and low fertile, coarse texture to moderate, moderately drained, shallow to moderate and low fertile, gravelly surface, moderatly drained, shallow to moderate and very low fertile respectively. Soil analysis reveled that there was high inherent risk of soil salinity and sodicity, especially unit 1. In general, the result showed that there were clear aspects of wind erosion represented as large areas affected by the sand encroachment form of crescent dunes and rocks interspersed with hills and plateaus. Furthermore, soils of the targeted area were formed from the accumulation of creeping and portable aeolian sands. The research site lies in the southeastern part of the border triangle between Sudan, Egypt, Libya and Chad, which is severely affected by wind erosion because the site was bare, open with no wind barriers or shelter belts, also this area falls under the sand moving winds of the Sahara. These are the northerly winds that prevail in Northern Darfur State. Furthermore, the prevalent climatic conditions including high temperature, rainless area and relatively high wind speed are conducive to high wind erosion. The area in danger unless serious measures carried out to reduce wind erosion. The area has very low potential suitability for agriculture. The study area was rich in wild life such as deer, rabbits, birds, many insects and snakes.
The research aims to study the temporal variability of wind speed and direction and their correlation with air temperature in different climatic seasons in Northern State, to produce broad data base on winds variability and interrelationship between air temperature and wind speed for different climatic seasons. Mean monthly and daily climatic data dating back to 2001(first season) and 2011(second season) were obtained from Karima meteorological station representing three different climatic seasons namely: April for summer, August for autumn and December for winter. Data were subjected to simple regression analysis, statistical analysis and computations were done by “Excel 2000”. The results showed that the wind speed varied widely during each month and day even within the same climatic season. In two seasons, the diurnal variation for different climatic seasons Apr., Aug. and Dec. was much lower than the monthly; due to the higher monthly variability of wind speed. The results also revealed that the prevailing direction of winds was generally northwards. The results of April in the first season are presented as an example; the mean daily wind speed (Va) ranged from 0.6 to 17m/s, with a mean of 7.2m/s, a STD of 4.3 and a CV of 60%. The daily mean data ranged from 5.4 (3hrs) to 8.2 (24hrs), with a mean of 7.2m/s, a STD of 1.1 and a CV of 15.3%.The prevailing wind direction decreases in the following order: N>NE=NNE>NNW. The monthly variability of the air temperature in the two seasons decreased in the following order: winter> summer> autumn. Significant, inversely proportional and cubic wind speed-temperature correlations in the two seasons for Aug. and Dec. were (P<0.05, r=0.362); (P<0.01, r= 0.488); (P<0.001, R=585) and (P<0.001, r= 0.679), respectively.
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