Abstract:
Based on artificial stimulation experiment, soil crack characteristics and runoff and sediment yields under different drought grades such as no drought, slight drought, medium drought and severe drought have been investigated with the help of photograph processing and statistical methods.The results suggested that soil crack length density, area density, width, intersection and curvature increased with the increasing of drought grade. In addition, the number of soil crack under slight drought was slightly less than medium drought, but much less than severe drought. Soil crack connectivity sharply increased from slight drought to medium slight with no differences between medium slight and severe drought. The starting time of runoff yield under slight drought, medium drought and severe drought increased by 1.83, 2.43 and 3.87 min than no drought, respectively, but the ending time decreased by 0.97, 1.23 and 1.40 min, respectively. Before stabilization of runoff producing, the runoff yields increased with increasing of drought grades, but there were no differences after stabilization of runoff. Total runoff yields decreased as the increase of drought grades. Average soil runoff yields increased from no drought to medium drought, but slightly decreased from medium drought to severe drought. Before stabilization of runoff producing, sediment yields decreased from slight drought to severe drought, with lowest sediment yields under no drought. Total sediment yields firstly increased and then decreased with the increase of drought grades. Total sediment yield under slight drought, medium drought and severe drought were 3.92, 3.85 and 2.50 times of that under no drought respectively.
