Land Use and Land Cover Changes in Northern Kordofan State of Sudan: A Remotely Sensed Data Analysis

Abstract

The North Kordofan region is semiarid and characterized by recurrent episodes of drought which led to increasing desertification. The agricultural and forest production in North Kordofan State (NKS), however, is adversely hampered by climate change, particularly the unreliable and fluctuated rainfall and desertification. Hence, it is expected that the land use/land cover (LULC) classes in the state would have dramatically changed during past decades. This study tries to detect the changes in LULC in NKS during the period between 1973 and 2001. We assess the desertification process using vegetation cover as an indicator. We used remotely sensed data from Landsat multispectral scanner (MSS; captured in 1973) and enhanced thematic mapper plus (ETM+; captured in 2001) to detect LULC conversion dynamics. Pre- and postclassification change detection methods were compared. A supervised image classification (maximum likelihood) is then performed to identify LULC classes. Ten major land cover classes are discriminated. These are forests, farms on sand, farms on clay, fallows on sand, fallows on clay, woodlands, mixed woodlands, grasslands, burnt/wetlands, and natural water bodies. The results revealed that using a preclassification image differencing procedure, positive (9.66 and 6.70 % of total area when near-infrared (NIR) and normalized difference vegetation index (NDVI) were used, respectively), negative (9.77 and 6.62 % of total area when NIR and NDVI were used, respectively), and no (80.57 and 86.68 % of total area when NIR and NDVI were used, respectively) vegetation changes were observed in the study area during the period 1973–2001. The study also indicates a negative change trend when principal component analysis (PCA) and change vector analysis (CVA) methods are employed. With respect to the postclassification method, the results show significant conversions in LULC classes, where new classes such as farms and fallows on clay soils were introduced in 2001, while woodlands in 1973 were completely shifted to farm on sand, farm on clay, fallow on sand, fallow on clay, grassland, and mixed woodland in 2001. The study demonstrates different signs of desertification in the study area related to change patterns in LULC classes, such as increase in farms on sand and clay soils at the expense of wood and grasslands. It is concluded that the vegetation cover in North Kordofan was negatively changed due to socioeconomic factors and desertification in the area was the main sign of such negative LULC changes.