## 1 Introduction  
Base-level variation has a significant impact on a geomorphological system with severe changes in channel incision rate, sediment flux, and spatial distribution of geomorphological processes [1; 2; 3]. A fast transition from endorheic (i.e. : centripetal drainage or closed basin) to exorheic drainage is one of the most relevant cases of disequilibrium of a landscape, because it promotes a non-linear response of the fluvial systems and a complex spatial and temporal response of river incision and sediment flux (see for example [4]). Several works have investigated the long-term response of the drainage network to a transition from endorheic to exorheic conditions due to complex climate- or tectonic-driven processes such as sediment overfilling, headward stream erosion, and threshold incision or fluvial capture [5; 6; 7; 8]. This kind of analysis is largely based on morphotectonic studies and related qualitative reconstruction of past stages of landscape evolution [9; 10; 11]. Dam construction and/or removal is one of the human-induced perturbations of the fluvial net with a stronger impact on the geomorphic system [12; 13; 14]. Many works have been focused on the analysis of the effects of this kind of disturbance on the fluvial network and sediment flux, highlighting a typical response that is strongly controlled by the post-dam river longitudinal profile. In fact, upstream knickpoint retreat generally promoted incision of both upland areas and reservoir infill, but several works have demonstrated that local factors such as rates of knickpoint migration [15; 16], bedrock erodibility [17; 18], grain-size and texture of reservoir sediment [19] and width of the reservoir [17; 19] can drive a complex response of river processes and promote a high spatial and temporal variability of erosion and deposition. Most of these studies are based on field and remote sensing data at limited spatial and temporal scales [17; 19; 20] or on the application of 1-D models [21; 22]. For example, extensive geomorphic analyses of dam removal scenarios have been conducted in the USA through: (i) the direct measurements of the post-dam modification of morpho-sedimentary features supported by one-dimensional hydrodynamic modeling [17]; or (ii) the application of channel evolution models such as CONCEPTS and DREAM [21; 22]. Such models have a significant limitation that they are not able to fully capture the spatial (i.e., lateral) distribution of river processes, channel modification, and sediment flux. In the last years, landscape evolution models (LEMs) have been extensively used to simulate short- and long-term geomorphic scenarios of sediment flux and topographic modification in different natural environments [23; 24; 25; 26; 27]. These studies have demonstrated that LEMs represent a powerful tool to predict morpho-sedimentary adjustments related to changes in land use, climate setting, and base levels [24; 28; 29; 30; 31]. Recently, the Caesar-Lisfool LEM was used to investigate the short-term (i.e., at a decadal scale) pattern and rates of geomorphic changes and associated sediment flux induced by removal of multiple dams in the middle reach of Kaja River, Austria [32]. The authors demonstrated the usefulness of the LEM to predict the 2-D geomorphological and sedimentary effect of the abrupt base-level fall related to dam removal. This kind of investigation overcomes the clear limitation of 1-D or empirical models and can provide a significant opportunity to modify different controlling factors such as climate setting, land use, vegetation growth, and sediment features. The main limitation of the application of such models is that a reliable calibration of a LEM is really complicated and several well-known reasons such as the difficulty of both the selection of model parameters and the absence of extensive validation of the prediction ability of the model results in natural environments could represent a significant limitation in its application in complex natural landscapes [25; 33].