ABSTRACT

The cause–effect relationship and rates of change of suspended sediment dynamics at catchment scales in the tropics remain poorly understood. This study used a chrono-sequence of remotely sensed land use and historical hydrometric data from 1985 to 2001 in three tropical streams of Mexico to analyse the temporal dynamics of land-use change and measured suspended sediment behaviour. The variations in measured suspended sediment concentrations (SSC) were related to land cover change using trend and hysteresis analysis. No statistically significant trends (p > 0.1) at a monthly scale were associated with the historical trajectories of stream sediment fluxes. However, intra-annual hysteresis allowed us to identify the climatic seasonality as a main driver for the discharge-sediment loops and to infer sediment source variations, related to land cover changes over time. The land cover change analysis, combined with statistical tests and hysteresis, was useful to identify temporal and spatial variations in sediment source dynamics.

摘要

热带集水区范围内悬浮沉积物动力学的因果关系和变化率仍然知之甚少。本研究使用 1985 年至 2001 年墨西哥三个热带河流中遥感土地利用和历史水文数据的时间序列来分析土地利用变化的时间动态并测量悬浮沉积物行为。测量的悬浮泥沙浓度 (SSC) 的变化与使用趋势和滞后分析的土地覆盖变化有关。没有统计上显着的趋势 ( p> 0.1) 与河流沉积物通量的历史轨迹相关。然而，年内滞后使我们能够将气候季节性确定为排放-沉积物循环的主要驱动因素，并推断与土地覆盖随时间变化有关的沉积物来源变化。土地覆盖变化分析与统计检验和滞后相结合，有助于识别沉积物源动态的时空变化。