ORIGINAL PAPER Effect of precipitation on the geological development of badlands in arid regions Peter Imumorin • Shahid Azam Received: 7 December 2009 / Accepted: 18 April 2010 / Published online: 21 May 2010 Ó Springer-Verlag 2010 Abstract The main objective of this paper was to study the effect of precipitation on the geological development of badlands in arid regions. Field observations and laboratory investigations were carried out to characterize the surface soils of the Avonlea badlands in southern Saskatchewan, Canada, which is currently experiencing a rapid develop- ment in infrastructure. Three distinct surface sediments were identified: an upper slope of cemented sandstone, a mid-slope on weathered mudrock and a relatively flat basal pediment. Each of these soils reacts differently to rainfall events. Precipitation results in grain size reduction which, together with the consistency limits, explains the water sensitivity of the soils; the fines increased by 16% in the cemented sandstone, 78% in the weathered mudrock and 33% in the basal pediment. Erosion susceptibility was highest in the basal pediment (2% clays) followed by cemented sandstone (cementation by 6% active clays) and then by weathered mudrock (cohesion due to the 40% clay). Keywords Climate Á Avonlea Á Slopes Á Badlands Á Consistency limit Á Desiccation Re ´sume ´ Le principal objectif de cet article a e ´te ´ d’e ´tudier les effets des pre ´cipitations sur le de ´veloppement du rav- inement et la formation des badlands dans les re ´gions de climat aride. Des observations de terrain et des travaux de laboratoire ont e ´te ´ re ´alise ´s afin de caracte ´riser les sols superficiels des badlands d’Avonlea, dans le sud-ouest du Saskatchewan au Canada, re ´gion qui connaı ˆt actuellement un important de ´veloppement d’infrastructures. Trois diffe ´rents mate ´riaux de surface ont e ´te ´ identifie ´s : un gre `s cimente ´ de haut de pente, une argilite de milieu de pente et un de ´po ˆt de pe ´diment de bas de pente. Chacun de ces sols re ´agit diffe ´remment aux e ´ve ´nements pluviome ´triques. Les pre ´cipitations ont pour conse ´quence une diminution de la taille des particules, ce qui, avec les indices de consistance, explique la sensibilite ´ des sols a ` l’eau. Les particules fines augmentent de 16% dans les gre `s cimente ´s, de 78% dans les argilites alte ´re ´es et de 33% dans les se ´diments de pe ´diment. La sensibilite ´a ` l’e ´rosion e ´tait plus e ´leve ´e dans les se ´diments de pe ´diment (avec 2% d’argiles) suivis par les gre `s cimente ´s (cimente ´s par 6% d’argiles actives) puis par les argilites alte ´re ´es (pre ´sentant une cohe ´sion du fait d’un pourcentage de 40% d’argiles). Mots cle ´s Climat Á Avonlea Á Pentes Á Badlands Á Consistance Á Dessication Introduction Badlands are commonly found in arid and semi arid regions where materials are transported by fluvial erosion. According to Bryan and Yair (1982), the geomorphic activity in such deposits is primarily associated with sea- sonal climatic variations. In sub-tropical Mediterranean areas, erosion occurs due to high intensity rainfalls in winter whereas soils desiccate during the hot and dry summer (Regues and Gallart 2004). Conversely, surface soils are covered with snow during the cold winters P. Imumorin SaskEnergy TransGas, SaskEnergy Place, 1777 Victoria Ave., Regina, SK S4P 4K5, Canada S. Azam (&) Environmental Systems Engineering, Faculty of Engineering and Applied Science, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada e-mail: Shahid.Azam@uregina.ca 123 Bull Eng Geol Environ (2011) 70:223–229 DOI 10.1007/s10064-010-0300-4