Unraveling the roles of asymmetric uplift, normal faulting and groundwater flow to drainage rearrangement in an emerging karstic landscape

Abstract

Landscape adjustment to tectonic, lithologic and climatic forcing leads to drainage reorganization and migration of divides. The respective contribution of these forcings, especially on carbonate landscapes is not well defined. Here, we have addressed this issue by combining field observations, satellite image interpretation and digital elevation model (DEM) quantitative analysis to assess drainage response to spatially heterogeneous rainfall, asymmetric uplift, and normal faulting on an emerging carbonated platform (Sumba Island, Indonesia). We map geomorphic markers of fluvial dynamics and drainage rearrangement and compute a χ parameter that incorporates the contributions of unevenly distributed precipitation and asymmetric uplift to estimate erosional disequilibrium across drainage divides. We find that asymmetric emergence of Sumba Island created an initial parallel drainage, asymmetric across a divide that propagates landwards. Soon after establishing itself on the emerging slopes this drainage was disturbed by normal faulting, which has become the main force driving drainage rearrangement. Vertical offsets across normal fault scarps first triggered aggradation within valleys over the hanging walls, and then disconnected upstream reaches from downstream reaches, leading to the formation of wind gaps atop the fault scarps and upstream perched sedimentary basins. The defeat of rivers by growing fault scarps was catalysed by the possibility for surface water to be rerouted near the fault scarps into underground water networks inside the underlying carbonates. At the end of the process, the opposite drainage across the main water divide captured the struggling drainage. Capture mechanisms include initial groundwater capture of the perched alluvial aquifers, followed by ground sapping at the head of the opposite drainage and surface stream diversion by avulsion. Finally, normal faulting is the main driving force of drainage rearrangement allowing avulsion and karstic rerouting whereas asymmetric uplift and climate forcings have shown a low efficiency. The role of karstification is more ambiguous, catalysing or inhibiting drainage rearrangement. Copyright © 2018 John Wiley & Sons, Ltd.

Slow Geodynamics and Fast Morphotectonics in the Far East Tethys

“…This result partly explains the ubiquitous uplifted Pleistocene coral reef sequences that festoon the islands of the Banda arc (Figure 1). Although some are uplifted due to tectonic contraction (for instance, Sumba island, Authemayou et al., 2018, Miller et al., 2021, or SE Sulawesi, Pedoja et al., 2018), the background uplift of the region is induced by the relaxation of the dynamic topography. This motion is well localized around the basin, while the Australian margin conversely continues to subside at present.…”

Late Quaternary drainage reorganization assisted by surface faulting: The example of the Katrol Hill Fault zone, Kachchh, western India

“…In general, river diversion is a less energy‐consuming way of modifying a river network, because it only implies the localized removal of a watershed and does not require significant modification of the network of flow lines (Brocard et al, 2011). However, river diversions have been widely reported, but the exact processes involved in the diversions are generally poorly documented, because the diagnostic features of such processes generally quickly disappear after a diversion, which means that proving diversion is difficult (Bishop, 1995; Brocard et al, 2011; Authemayou et al, 2018). In the case of our study area, the role of river diversion and the occurrence of top‐down process is found to be prominent during the drainage realignment in the Gunawari River basin.…”

“…Drainage reorganization involves modification of drainage lines and this may be caused by tectonic activity (Bishop, 1995). An increasing number of studies in river basins around the world reveal show large‐scale landscape changes and drainage reorganization (Almeida‐Filho & Miranda, 2007; de Fátima Rossetti et al, 2005; Franzinelli & Igreja, 2002; Silva et al, 2007), for example, the Amazon River basin (Authemayou et al, 2018; Babault et al, 2012; Hayakawa et al, 2010; Mantelli et al, 2009; Rossetti & Góes, 2008); the Yarlung Zangbo–Brahmaputra River system (Bracciali et al, 2015; Ghosh et al, 2015; Jiang et al, 2016; Korup & Montgomery, 2008; Lahiri & Sinha, 2012; Lang & Huntington, 2014; Schmidt et al, 2015; Zeitler et al, 2001; Zhang et al, 2012) and the Three River watershed (Whipple et al, 2017; Yang et al, 2016). Plate tectonics and the evolution of passive margins have been identified as critical for understanding the long‐term landscape evolution and drainage history (Bishop, 1995, 1998; Harel et al, 2019; Summerfield, 1985, 1991), along with them being the prime cause of macroscale “drainage rearrangement” phenomenon (Bishop, 1986, 1988; Driscoll & Karner, 1994; Oilier, 1982; van de Graaff et al, 1977).…”

“…The majority of the studies of drainage reorganization encompass large temporal and spatial scales. Most of these describe continental to regional scale river captures with a reported range in age from 100 ka to more than 20 Ma (Antón et al, 2014; Aslan et al, 2014; Authemayou et al, 2018; Bracciali et al, 2015; Prince et al, 2011; Robl et al, 2017; Zheng et al, 2013). In such cases, the processes of river incision and river basin reorganization are difficult to observe (Antón et al, 2014; Bracciali et al, 2015; Shugar et al, 2017; Yanites et al, 2013; Zheng et al, 2013).…”

“…Some features, such as river elbows and barbed tributaries, can persist for millions of years, but they do not reveal much about the diversion process and its effects. Some studies have elaborated the impact of river diversions on the upstream drainage in medium‐sized catchments (Authemayou et al, 2018; Giletycz et al, 2015; Stokes et al, 2002). Studies of drainage reorganizations in smaller scale drainage basins and sub‐basins are generally rare (Harel et al, 2019).…”