Hydrological model of the Shase-Limpopo basin

This video presents the hydrological characterisation of the Limpopo and Shashe Rivers. The model integrates spatial analysis from Arc-GIS 10, remotely sensed data, mean statistical rainfall averages, and elevation dataset. For the Shashe-Limpopo basin context, the yellow circle covers Samaria floodplain and the black circle covers Mapungubwe landscape. As rainfall changes from 300 to 450 millimetres in the Shashe-Limpopo basin, the lowest lying sinks of the main channel fill up first. These are highlighted in green arrows. As the water collects in nearby streams and low lying sinks down-stream, The narrow gorge features (circled orange in-text) downstream of the Shashe-Limpopo confluence act as dam wall buffers, such that the intensity of flooding episodes are reduced (as shown in Figure fifty). Noteworthy, a similar process was recorded by Fredrick Elton while crossing the middle Limpopo valley in the 1870s. In a nutshell, the simulation shows that narrow passage/gorges act as a dam wall against the Shashe-Limpopo Rivers, forcing it to back up and inundate its tributaries. A clear indication of channel resilience. The resulting model shows that heavy flooding occurs in low-lying valley plains due to the gradual overflow of the Shashe and Limpopo Rivers. In fact, supporting evidence for these hydrological processes is found in the soil micromorphological records of this are and, specifically, the presence of micro-laminar pedofeatures linked to overbank clastic sedimentation (as discussed in Chapter 5, section 5.7). Thank you for watching

本视频针对林波波河（Limpopo）与沙谢河（Shashe）开展水文特征表征研究。本研究所用模型整合了ArcGIS 10的空间分析功能、遥感影像数据、统计降雨均值数据集以及高程数据集。在沙谢-林波波流域语境下，黄色圆圈标注的区域为萨玛利亚泛滥平原，黑色圆圈标注的区域为马蓬古布韦地貌区。当沙谢-林波波流域的降雨量从300毫米升至450毫米时，主河道最低洼的汇水区会率先被填满，该区域以绿色箭头标注。当水体在下游附近溪流与低洼汇水区汇聚时，沙谢河与林波波河汇流点下游的狭窄峡谷（文中以橙色圆圈标注）可起到类似坝体的缓冲作用，从而降低洪水暴发的强度，具体如图50所示。值得注意的是，19世纪70年代弗雷德里克·埃尔顿（Fredrick Elton）在穿越林波波河中游河谷时，曾记录到类似的水文过程。简言之，模拟结果表明，狭窄河道与峡谷可对沙谢河与林波波河起到坝体阻滞作用，迫使河流水体倒灌并淹没其支流，这直观体现了河道的韧性。最终模型结果显示，由于沙谢河与林波波河的逐步漫溢，低洼河谷平原区域会发生严重洪涝灾害。事实上，该区域的土壤微形态记录可为上述水文过程提供佐证，尤其是与岸后碎屑沉积相关的微层状土壤特征（详见第5章第5.7节）。感谢观看