Coping strategies with agrometeorological risks and uncertainties for water erosion, runoff and soil loss

The pressure of increasing world population demands for higher crops yields from the finite area of productive agricultural lands. Meeting the needs especially in developing countries through more intensive use of existing agricultural lands and expansion into more marginal lands will substantially increase erosion. There is an urgent need to take preventive and control measures to mitigate the threat to global food security. These concerns are supported by a report by El Swaify (1994) that the annual rates of soil erosion can often range between 20 to over 100 t ha−1, which results in about 15–30 per cent annual decline in the soil productivity. An estimated loss of about 6 million ha annually is estimated as a result of degradation by erosion and other causes (Pimental et al. 1993). The data for these estimates are often selective from small scale studies conducted over short time periods, however, this does draws attention to the increasing problem of soil loss. In the western world the loss in productivity from erosion may be masked or compensated by increased costly and efficient management practices such as improved crop varieties, fertilizer, pesticides, and irrigation. Even under these management practices, soil erosion has continued and sediment loss has become a very costly factor in the overall picture.