LANDSCAPE DEVELOPMENT IN BADLANDS 1417 Copyright © 2004 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms 29, 1417–1430 (2004) Earth Surface Processes and Landforms Earth Surf. Process. Landforms 29, 1417–1430 (2004) Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/esp.1115 SPATIAL DISTRIBUTION OF SURFACE PROPERTIES, RUNOFF GENERATION AND LANDSCAPE DEVELOPMENT IN THE ZIN VALLEY BADLANDS, NORTHERN NEGEV, ISRAEL NIKOLAUS J. KUHN, 1 * AARON YAIR 2 AND MILICA KASANIN GRUBIN 3 1 Department of Geography, School of Geography, Archaeology and Earth Resources, University of Exeter, Amory Building, Rennes Drive, Exeter, EX4 4RJ, UK 2 Department of Geography, Hebrew University, Mt Scopus Campus, Jerusalem 91905, Israel 3 Soil Erosion Laboratory, University of Toronto, 1265 Military Trail, Scarborough, Ontario, Canada Received 4 June 2003, Revised 8 March 2004, Accepted 20 April 2004 ABSTRACT Infiltration tests, soil mapping and soil property analysis were used to assess the effect of within-storm rainfall conditions on spatial patterns of surface characteristics relevant for runoff generation, continuity and erosion in the Zin Valley Badlands. Runoff and erosion differ strongly between ridges and slopes. Soils at both locations are susceptible to sealing, but on the sideslopes deep desiccation cracks inhibit continuous flow, even during high magnitude rainstorms. The discontinuous nature of runoff has a feedback on surface conditions. Erosion on the ridges maintains shallow soils prone to sealing while infiltration and deposition on the sideslopes enhance soil depth, a prerequisite for stable desiccation cracks. Some runoff generated on the ridges is transmitted to the valley via rills. On straight sideslopes, rills are single and often discontinuous, indicating limited frequency of continuous runoff. Along concave valley heads, rill systems are well integrated and continu- ous, concentrating runoff and reducing infiltration losses along slopes. The longitudinal, V-shaped valley morphology of small catchments in the Zin Valley Badlands reflects the long-term effect of different erosion rates in valley heads and on sideslopes. Over time, valley incision lengthened the sideslopes, reducing the portion of annual rainfall that was runoff-effective. Once sideslopes reached a critical length that inhibited frequent continuous flow, a colluvium with an increased infiltration capacity developed, reducing runoff frequency even further. Consequently, erosion on the valley sideslopes decreased. Continuous flow from ridges to the valley channel remained more common in integrated rill systems in concavities and valley heads, leading to more erosion and retreat of the valley heads. The spatial patterns of runoff and erosion in the Zin Valley Badlands demonstrate that landscape development is strongly affected by processes that lead to differentiation of soil properties on hillslopes with uniform lithology. The patterns of surface characteristics and their role in landscape development are strongly dependent on rainfall conditions, highlighting the need for geomorphologists to identify the dynamic spatial and temporal scales relevant for landscape development. Copyright © 2004 John Wiley & Sons, Ltd. KEY WORDS: landscape development; badlands; soil properties; partial area contribution; rainfall characteristics INTRODUCTION Landscape development in badlands is commonly associated with a close linkage between the dominant erosion process and lithology (Schumm 1956a, b; Campbell, 1997). On fine-grained sandstone with low permeability, small amounts of rainfall can be sufficient for initiation of surface runoff on steep valley sideslopes. Flow concentration in cracks or pipes leads to rill development and the frequent continuous surface runoff causes retreat of slopes and widening of valleys (Schumm, 1956b). In badlands dominated by mudstones, surface sealing often reduces infiltration rates rapidly; however, by-pass flow through desiccation cracks inhibits con- tinuous surface flow (Campbell, 1997). Flow through the desiccation cracks facilitates piping and rill incision, * Correspondence to: N. J. Kuhn, Department of Geography, School of Geography, Archaeology and Earth Resources, University of Exeter, Amory Building, Rennes Drive, Exeter, EX4 4RJ, UK. E-mail: n.kuhn@exeter.ac.uk