ABSTRACT

In small catchments, the time interval most commonly used for simulation – daily or monthly – may not be sufficient to accurately capture the time distribution of hydrological processes. In this paper, the Soil and Water Assessment Tool (SWAT) was used to perform an hourly long-term streamflow and sediment load simulation in the small (4.8 km²) and forested Aixola catchment (northern Spain). From this simulation, 10 runoff events were tested; the most satisfactory results for streamflow were obtained under wet antecedent conditions. However, simulated sediment load was underestimated during the peaks and remained high towards the end of the event. Furthermore, the influence of the precipitation time step (1–4 h, daily) was not relevant in the streamflow simulation but does influence the sediment simulation. The best results were achieved with the daily step simulations obtained at an hourly time step. This paper shows that sub-daily modelling improves water and especially sediment yield results; however, improvements are still needed in timing-related routines.

摘要

在小流域，最常用于模拟的时间间隔（每天或每月）可能不足以准确地记录水文过程的时间分布。本文使用土壤和水评估工具（SWAT）在小面积（4.8 km ²）和密林的Aixola集水区（西班牙北部）。从该模拟中，测试了10个径流事件。在湿前条件下获得了最令人满意的水流结果。但是，模拟的沉积物负荷在峰值期间被低估了，并且在事件结束时仍然很高。此外，降水时间步长（每天1-4小时）的影响与水流模拟无关，但确实会影响沉积物模拟。以每小时的时间步长获得的每日步长仿真可以实现最佳结果。本文表明，次日模拟可以改善水，尤其是泥沙产量的结果。但是，与计时相关的例程仍需要改进。