A study on cracking in some Vertisols of the Sudan

Development of a method for estimating the likelihood of crack flow in Canadian agricultural soils at the landscape scale. Can. J. Soil Sci. 90: 129Á149. Indicators of risk of water contamination by agricultural pollutants are developed in Canada to assess sustainability of agriculture. Crack flow (CF), a key pathway for sub-surface contaminant transport, is part of the transport-hydrology algorithm used in two of these risk indicators. The objective was to develop a methodology for predicting the likelihood of CF in Canadian agricultural soils at the landscape scale. The algorithm considers soil clay content, crack development followed by a runoff event based on water budget, tile drainage, and crops. More than 40% of Canadian farmlands had moderate to very high likelihood of CF, mainly in Manitoba, Ontario and Quebec, due to frequent runoffs on cracked clay soils potentially contributing to groundwater contamination. In Ontario and Quebec, farmlands with high CF likelihood correspond to regions under intensive tile drainage, which increases the risk of lateral translocation of contaminants to surface water bodies. Besides being a component of risk indicators of water contamination by phosphorus and coliforms, the CF algorithm and maps can be used to identify areas at risk of subsurface water contamination. Best management practices, adapted to reduce CF can then be targeted to these areas.

Section: Rationale Of Crack Flowmentioning

confidence: 99%

Development of a method for estimating the likelihood of crack flow in Canadian agricultural soils at the landscape scale

Dadfar¹,

Allaire²,

Jong³

et al. 2010

“…The method of measuring the size of cracks was essentially that described in El Abedine and Robinson (1971) whereby the width and depth ofcracks intercepting two 20-m tapes, placed at right angles to each other. were measured.…”

Section: Crack-size Measurementmentioning

confidence: 99%

“…Linear shrinkage was calculated as (cumulative width of cracks in metres x 100)/(cumulative length of tape in metres). Volume of cracks was calculated using the formula given in El Abedine and Robinson (1971 Schafer and Singer (1976) for some swelling clay soils of California; however, the analytical model proposed by them, which assumes all the swelline is interlamellar, underestimates COLE foithe soils included in this study. This may be explained by considering that interlamellar swelling constitutes a small portion of the total shrinkage (Green-Kelly 1974) and that the surface area governs shrink-swell behavior (Low 1986).…”

Section: Crack-size Measurementmentioning

confidence: 99%

Shrink-Swell Potential and Cracking in Clay Soils of Saskatchewan

Dasog¹,

Acton²,

Mermut³

et al. 1988

potential and cracking in clay soils of Saskatchewan. Can. J. Soil Sci. 68:251-26O.Clay soils in Saskatchewan were studied to understand their shrink-swell potential, to identify soil properties that predict the coefficient oflinear extensibility (COLE), and to assess the extent of cracking during the growing season. The soils have medium to very high shrink-swell potential, which is related to the specific surface area associated with expandable clays. Because expandable clays in these soils are predominantly of fine clay size, COLE is reasonably well predicted from percent fine clay. The extent of cracking is estimated for some sites using an improved method of measurement.Limited data suggest that cracking intensity in native grassland is less than in cultivated sites and that, under wheat, it is more pronounced in subarid than in subhumid sites.

“…Cracks observed in this study were, on average, larger than cracks observed in other studies. El Abedine and Robinson (1971); Yaalon and Kalmar (1978); Dasog et al (1988) and Dasog and Shasidhara (1993) measured cracks 0.9-18 cm wide, 27-154 cm long and 39-867 m 3 ha -1 . Glazovskya (1981) reported a similar total volume of soil contraction in Vertisols of Russia.…”

Section: Size Parameters Of Shrinkage Cracks In Vertisols Of Northeasmentioning

confidence: 99%

“…Some of these cracks open wider later in the drying process in three dimensions (Marshall 1982). Desiccation cracks may have horizontal dimensions of 0.9 to 18 cm in width and vertical dimensions of 27 to 70 cm in depth (El Abedine and Robinson 1971;Yaalon and Kalmar 1978;Jewitt et al 1979;Dasog et al 1988;Dasog and Shashidhara 1993).…”

mentioning

confidence: 99%

The contribution of shrinkage cracks to bypass flow during simulated and natural rainfall experiments in northeastern Mexico

Návar¹,

Mendez²,

Bryan³

et al. 2002

. 2002. The contribution of shrinkage cracks to bypass flow during simulated and natural rainfall experiments in northeastern Mexico. Can. J. Soil Sci. 82: 65-74. Understanding the spatial and temporal dynamics of desiccation cracks and related hydro-geomorphologic processes is a key component for the sustainable management of water resources in Vertisols. The contribution of shrinkage cracks to infiltration of runoff and sediments was studied during natural and simulated rainfall experiments in Vertisols of the semi-arid plains of northeastern Mexico during the summer of 1998. Surface runoff amounted to 10.7% of the total applied rainfall, but it increased from 2.3 to 18.3% during the first and last applied rainfall. Soil cracks partially filled with transported sediments in surface runoff, but never sealed by swelling or by sedimentation during the sprinkling of 180 mm of rainfall applied in three installments during 1 wk. However, cracks observed in 1999 closed during natural rainfalls with a total depth of 450 mm, distributed in 10 storms during 3 mo. The development of soil cracks and their contribution to promote short-circuit flow are highly variable processes in time and space. Pour gérer de façon durable les ressources hydriques dans les vertisols, il est capital de comprendre la dynamique spatiale et temporelle des crevasses causées par la sécheresse et des processus hydro-géomorphologiques connexes. Les auteurs ont étudié comment les fentes de retrait modifient l'infiltration des eaux de ruissellement et des sédiments dans les vertisols lors de précipitations naturelles et artificielles. Les expériences se sont déroulées dans les plaines semi-arides du nord-est du Mexique durant l'été 1998. Le ruissellement représente 10,7 % des précipitations artificielles totales, mais passe de 2,3 % à 18,3 % entre la première et la dernière précipitation. Les crevasses dans le sol se remplissent partiellement de sédiments charriés par les eaux de ruissellement, mais elles ne sont jamais obturées par gonflement ou sédimentation quand on déverse 180 mm d'eau sur le sol en trois étapes, réparties sur une semaine. En 1999, les fentes se sont néanmoins refermées jusqu'à une profondeur de 450 mm après des précipitations naturelles correspondant à 10 orages survenus en 3 mois. L'apparition de crevasses dans le sol et la contribution de ces dernières à un écoulement limité sont des processus qui varient considérablement dans l'espace et le temps.