Advanced

Spatial soil loss risk and reservoir siltation in semi-arid Tunisia

Jebari, Sihem; Berndtsson, Ronny LU ; Bahri, Akissa and Boufaroua, Mohamed (2010) In Hydrological Sciences Journal 55(1). p.121-137
Abstract
Soil erosion vulnerability and extreme rainfall characteristics over the Mediterranean semi-arid region of Tunisia are crucial input for estimation of siltation rate in artificial reservoirs. A comprehensive high-resolution database on erosive rainfall, together with siltation records for 28 small reservoirs, were analysed for this region, the Tunisian Dorsal (the easternmost part of the Atlas Mountains). The general life-span of these reservoirs is only about 14 years. Depending on the soil degradation in the different catchments, the corresponding reservoirs display a wide range of soil erosion rates. The average soil loss was 14.5 t ha(-1) year(-1) but some catchments display values of up to 36.4 t ha(-1) year(-1). The maximum 15-min... (More)
Soil erosion vulnerability and extreme rainfall characteristics over the Mediterranean semi-arid region of Tunisia are crucial input for estimation of siltation rate in artificial reservoirs. A comprehensive high-resolution database on erosive rainfall, together with siltation records for 28 small reservoirs, were analysed for this region, the Tunisian Dorsal (the easternmost part of the Atlas Mountains). The general life-span of these reservoirs is only about 14 years. Depending on the soil degradation in the different catchments, the corresponding reservoirs display a wide range of soil erosion rates. The average soil loss was 14.5 t ha(-1) year(-1) but some catchments display values of up to 36.4 t ha(-1) year(-1). The maximum 15-min duration rainfall intensity was used to determine the spatial distribution of rainfall erosivity. The northwestern parts of the Tunisian Dorsal display the most extreme rainfall erosivity. Spatial erosion patterns are to some extent similar; however, they vary greatly according to their location in the "soil degradation cycle". This cycle determines the soil particle delivery potential of the catchment. In general, the northwestern parts of the Dorsal display modest soil erosion patterns due to the already severely degraded soil structure. Here, the soil surface is often the original bedrock. However, the greatest soil erosion occurs in the mid-eastern parts of the Dorsal, which represents the "degradation front". The latter corresponds to the area with highest erosion, which is continuously progressing westward in the Dorsal. The large variation between the erosive rainfall events and the annual soil loss rates was explained by two important factors. The first relates to the soil degradation cycle. The second factor corresponds to the degradation front with the highest soil loss rates. At present this front is located at 300 m altitude and appears to be moving along an 80-km westward path starting from the east coast. A better understanding of the above can be used to better manage soils and soil covers in the Tunisian Dorsal area and, eventually, to decrease the soil erosion and reservoir siltation risk. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
degradation cycle, Atlas mountain range, erosive rainfall, gully, erosion, inter-rill erosion, semi-arid, rill erosion, siltation, distribution, small reservoirs, Tunisia
in
Hydrological Sciences Journal
volume
55
issue
1
pages
121 - 137
publisher
IAHS Press
external identifiers
  • wos:000278012900010
  • scopus:77955277270
ISSN
0262-6667
DOI
10.1080/02626660903529049
project
MERGE
The Middle East in the Contemporary World (MECW)
language
English
LU publication?
yes
id
563d293e-3f19-4112-a570-5f7b98f508a0 (old id 1616779)
date added to LUP
2010-06-22 13:36:01
date last changed
2018-05-29 11:48:06
@article{563d293e-3f19-4112-a570-5f7b98f508a0,
  abstract     = {Soil erosion vulnerability and extreme rainfall characteristics over the Mediterranean semi-arid region of Tunisia are crucial input for estimation of siltation rate in artificial reservoirs. A comprehensive high-resolution database on erosive rainfall, together with siltation records for 28 small reservoirs, were analysed for this region, the Tunisian Dorsal (the easternmost part of the Atlas Mountains). The general life-span of these reservoirs is only about 14 years. Depending on the soil degradation in the different catchments, the corresponding reservoirs display a wide range of soil erosion rates. The average soil loss was 14.5 t ha(-1) year(-1) but some catchments display values of up to 36.4 t ha(-1) year(-1). The maximum 15-min duration rainfall intensity was used to determine the spatial distribution of rainfall erosivity. The northwestern parts of the Tunisian Dorsal display the most extreme rainfall erosivity. Spatial erosion patterns are to some extent similar; however, they vary greatly according to their location in the "soil degradation cycle". This cycle determines the soil particle delivery potential of the catchment. In general, the northwestern parts of the Dorsal display modest soil erosion patterns due to the already severely degraded soil structure. Here, the soil surface is often the original bedrock. However, the greatest soil erosion occurs in the mid-eastern parts of the Dorsal, which represents the "degradation front". The latter corresponds to the area with highest erosion, which is continuously progressing westward in the Dorsal. The large variation between the erosive rainfall events and the annual soil loss rates was explained by two important factors. The first relates to the soil degradation cycle. The second factor corresponds to the degradation front with the highest soil loss rates. At present this front is located at 300 m altitude and appears to be moving along an 80-km westward path starting from the east coast. A better understanding of the above can be used to better manage soils and soil covers in the Tunisian Dorsal area and, eventually, to decrease the soil erosion and reservoir siltation risk.},
  author       = {Jebari, Sihem and Berndtsson, Ronny and Bahri, Akissa and Boufaroua, Mohamed},
  issn         = {0262-6667},
  keyword      = {degradation cycle,Atlas mountain range,erosive rainfall,gully,erosion,inter-rill erosion,semi-arid,rill erosion,siltation,distribution,small reservoirs,Tunisia},
  language     = {eng},
  number       = {1},
  pages        = {121--137},
  publisher    = {IAHS Press},
  series       = {Hydrological Sciences Journal},
  title        = {Spatial soil loss risk and reservoir siltation in semi-arid Tunisia},
  url          = {http://dx.doi.org/10.1080/02626660903529049},
  volume       = {55},
  year         = {2010},
}