Water in alluvial fill in an area of extreme aridity / מים במילוי אלוביאלי באיזור צחיח קיצון
The alluvial body of Nahal Yael is between two gauging stations 1 km apart. Losses of water in the alluvium during flood affect floodwave generation and play a role in the general rainfall-runoff relationship of the dranage. The volume of alluvium in the channel is 12,500 cubic m with a maximum dept...
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Veröffentlicht in: | אופקים בגיאוגרפיה 1990-01 (31), p.109-122 |
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Format: | Artikel |
Sprache: | heb |
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Zusammenfassung: | The alluvial body of Nahal Yael is between two gauging stations 1 km apart. Losses of water in the alluvium during flood affect floodwave generation and play a role in the general rainfall-runoff relationship of the dranage. The volume of alluvium in the channel is 12,500 cubic m with a maximum depth of 3.20 m. The average depth of alluvium is between 1.5-2.0 m. Alluvial material is mainly coarse with little fines. Porosity is 33%. Seven flood events were analysed. Results show the maximum water absorption capacity of the alluvium to be 4,500 cubic m. A relationship was found between the interflood drying time and the absorptive capacity of the alluvium. Two salient factors control the infiltration capacity of the alluvium: (a) grain size distribution, and (b) percentage of antecedent moisture. The alluvial body acts as a temporary water storage during flood. In prolonged rainfall events this storage reaches an equilibrium. Alluvium saturation is completed prior to floodwave generation and precedes its migration downstream. Though direct evidence is lacking, deep infiltration at the alluvium/bedrock boundary is probably negligible. |
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ISSN: | 0334-3774 |