the time. Areas around Wadi Halfa and along the Egyptian border can easily pass many years or many decades without seeing any rainfall at all. They are also among the hottest places during their summertime and their "wintertime" : averages high temperatures routinely exceed 40 °C (104 °F) for four to nearly six months a year to reach a maximum peak of about 45 °C (113 °F) in some places and averages high temperature remain above 24 °C (75.2 °F) in the northernmost region and above 30 °C (86 °F) in places such as Atbara or Meroe. Environmental issues Sudan faces some severe environmental problems, most related either to the availability of water or its disposal. Among them are desertification, land degradation, and deforestation. Desertification, the southward shift of the boundary between desert and semidesert, has occurred at an estimated rate of 50 to 200 kilometers since records of rainfall and vegetation began in the 1930s. Its impact has been most notable in North Darfur and North Kordofan. Desertification is likely to continue its southward progression because of declining precipitation and will lead to continued loss of productive land. Agriculture, particularly poorly planned and managed mechanized agriculture, has led to land degradation, water pollution, and related problems. Land degradation has also resulted from an explosive growth in the size of livestock herds since the 1960s that has overtaxed grazing areas. Deforestation has occurred at an alarming rate. Sudan as a whole might have lost nearly 12 percent of its forest cover between 1990 and 2005, or about 8.8 million hectares, a loss driven primarily by land clearance and energy needs. Compounding Sudan’s environmental problems are long years of warfare and the resultant camps for large numbers of internally displaced people, who scour the surrounding land for water, fuel, and food. United Nations (UN) experts predict that riverbank erosion and loss of fertilizing silt will occur from Sudan’s current ambitious program of dam construction on the Nile and its tributaries. In urban areas, rapid and uncontrolled population influx into Khartoum and other cities and towns and the general lack of facilities to manage solid waste and sewage are among major environmental concerns. Area and land use Sudan has a land area of and a total area of . Approximately was irrigated as of 2012. Land boundaries The length of Sudan's borders is . Border countries are Central African Republic (), Chad