The Role of Rainfall Intensity and Soil in Determining Rates of Flow Through Cryoturbated Chalk

Authors

  • M. Mahmood-ul- Hassan * Department of Soil Science, The University of Reading, Whiteknights, PO Box 233, Reading, Berkshire, RG6 6DW, UK Institute of Natural Resources and Environmental Sciences, National Agricultural Research Centre, Islamabad-45500, Pakistan mmh@comsats.net.pk
  • P. J. Gregory Department of Soil Science, The University of Reading, Whiteknights, PO Box 233, Reading, Berkshire, RG6 6DW, UK Scottish Crop Research Institute, Invergowrie, Dundee, DD2 1QJ, UK

Keywords:

: breakthrough time, cryoturbated chalk; rainfall intensity; water flow

Abstract

 The effects of different water application rates (3, 10, 15 and 30 mm/h) and of topsoil removal on the rate of downward water movement through the cryoturbated chalk zone in southern England were investigated in situ. During and after each application of water, changes in water content and matric potential of the profile were monitored and percolate was collected in troughs. The measured water breakthrough time showed that water moved to 1.2 m depth quickly (in 8.2 h) even with application rate as low as 3 mm/h and that the time was only 3 h when water was applied at a rate of 15 mm/ h. These breakthrough times were about 150 and 422 fold shorter, respectively, than those expected if the water had been conducted by the matrix alone. Percolate was collected in troughs within 3.5 h at 1.2 m depth when water was applied at 30 mm/h and the quantity collected indicated that a significant amount of the surface applied water moved downward through inter-aggregate pores. The small increase in volumetric water content (about 3%) in excess of matrix water content resulted in a large increase in pore water velocities, from 0.20 to 5.3 m/d. The presence of soil layer had effect on the time taken for water to travel through the cryoturbated chalk layer and in the soil layer, water took about 1-2 h to pass thorough, depending on the intensity.

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Published

2008-09-25

How to Cite

Hassan, M. M.- ul-., & Gregory, P. . J. (2008). The Role of Rainfall Intensity and Soil in Determining Rates of Flow Through Cryoturbated Chalk. Biological Sciences - PJSIR, 51(5), 235–241. Retrieved from https://v2.pjsir.org/index.php/biological-sciences/article/view/677