An emerged coral reef terrace sequence flanks the northern coast of Sumba Island in Indonesia. The sequence was created by the joint effects of uplift and Quaternary sea level oscillations. Since its emergence, it undergoes chemical erosion, which is facilitated by its carbonate lithology. The morphology is dissected by multiple catchments drained by deep canyons, whose stream profiles display several knickpoints. We applied a multi-methods approach using high-resolution topographic data (Pleiades imagery), geomorphological analysis and denudation rates derived from ³⁶Cl cosmogenic nuclide concentrations to characterize the dynamics of these coastal drainages. We specifically investigate (1) the channel response to eustatic forcing, by analyzing knickpoint dynamics along a longitudinal river profile, and (2) the control of internal and external forcing over the catchment-scale erosion. Firstly, knickpoints form at the distal edge of the emergent reef at each regressive stage following a sea level highstand. The knickpoint propagates and rotates upward by regressive erosion. Knickpoint propagation rate decreases sharply over time until it becomes negligible before the next sea-level rise, which implies a marked decline in knickpoint retreat rate before its resorption. We attribute the inability of the river at Cape Laundi to fully propagate eustatic oscillations to its low stream discharge and low sediment supply, related to its small drainage area, to the karstic nature of the coral reef terraces composing the sequence, and to the high frequency of eustatic forcing. Secondly, average denudation rates calculated from ³⁶Cl cosmogenic nuclide concentrations of sands collected at the outlet of five catchments draining the sequence amount to 69 ± 8 mm·ka⁻¹. We emphasize the role of canyon areas in driving the denudation of the major catchments. However, no first-order correlation has been observed between catchment metrics, uplift rates and denudation rates. Finally, our correlations between catchment finite eroded volumes and uplift rates highlight the tendency of catchments to widen with low uplift rate and to lengthen while incising the sequence deeply with higher uplift rates.

印度尼西亚松巴岛北部海岸两侧出现了一个珊瑚礁阶地序列。该序列是由抬升和第四纪海平面振荡的共同作用产生的。自其出现以来，它经历了化学侵蚀，这得益于其碳酸盐岩性。形态由深峡谷排水的多个集水区解剖，其溪流剖面显示几个小点。我们使用高分辨率地形数据（昴宿星影像）、地貌分析和从³⁶Cl 宇宙成因核素浓度来表征这些沿海排水系统的动态。我们通过分析沿纵向河流剖面的临界点动态，专门研究了 (1) 通道对静静力强迫的响应，以及 (2) 对流域尺度侵蚀的内部和外部强迫的控制。首先，在海平面高位之后的每个海退阶段，在出水礁体的远侧边缘形成折点。折点通过回归侵蚀传播和向上旋转。随着时间的推移，切口传播率急剧下降，直到在下一次海平面上升之前变得可以忽略不计，这意味着在其吸收之前，切口撤退率显着下降。我们将 Laundi 角的河流无法完全传播静海振荡归因于其低流量和低沉积物供应，与它的小流域，构成序列的珊瑚礁阶地的岩溶性质以及高频的强迫症。其次，平均剥蚀率由下式计算在排放序列的五个集水区出口处收集的沙子的³⁶ Cl 宇宙成因核素浓度为 69 ± 8 mm·ka ^-1。我们强调峡谷地区在推动主要集水区剥蚀方面的作用。然而，在流域指标、抬升率和剥蚀率之间没有观察到一阶相关性。最后，我们在流域有限侵蚀量和抬升率之间的相关性突出了流域随着抬升率低而扩大的趋势，并在抬升率较高的情况下深入切割序列时会延长。