Impact Assessment of Changing Landcover on Flood Risk in the Indus River Basin Using the Rainfall-Runoff-Inundation (RRI)

Flooding is frequent in the province of Punjab, Pakistan, because the Indus River is a confluence point of five rivers. Researchers have primarily focused on the northern parts of the Indus basin and they have reported on simulation models that can be applied to the evaluation of flood risk. However, the inundation risks in the southern parts of the basin, including the impact of urbanization in this region, require a further assessment. The severity of flood disasters in the upper and lower reaches of the Indus basin are equally important because flash floods and riverine flooding pose a threat to densely populated areas. In this work, we aim to simulate flooding and the effects of landcover changes on inundation in the upper and lower Indus basin. Inundation was determined using the Rainfall-Runoff-Inundation (RRI) model with rainfall data from the monsoon season (00:00 UTC 1 July 2015-00:00 UTC 1 September 2015) as the input. After validating the model, sensitivity experiments were conducted to analyze the effect of landcover changes on the inundation of the Indus basin. The RRI model results showed that planting in the bare and vegetated areas led to minimum inundation in the Indus basin. Based on these results, planting between the Indus River and Chenab River could prevent flood disasters downstream of the confluence point as the discharge values reduced from 15,695.2 m(3)/s to 12,078.3 m(3)/s and 4373.7 m(3)/s to 2934.6 m(3)/s in the Indus River and Chenab River, respectively, before the confluence point. In contrast, urbanization in Punjab increased the risk of inundation after the confluence point caused by an increased discharge from 12,078.3 m(3)/s to 14,190.4 m(3)/s and 2934.6 m(3)/s to 4229.5 m(3)/s in the Indus River and Chenab River, respectively, before the confluence point.