Modelling of Rawal Catchment Area using Semi-Distributed Hydrological Model

Abstract

Pothwar plateau is among some of the most fascinating landscapes. The area is bounded by the salt range in the south, Murree Hills in the north and Kohat plateau in the west. Here several peaks of mountain deeply incised valleys have resulted in ecological depressions storing large amount of runoff after rainfall. Murree Hills and abutting gules lies among the front ranges of the Western most extension of the Himalayas. Altitude ranges from 500-2200 m a.s.l. The topography is steep to precipitous, with number of narrow gorges. The important rivers are Soan and Korang. Soan River originates from within few km of the Murree Hills flow through the hilly terrain for the initial 16 km to enter the plains near Pharwala Fortress and take southwardly course. It finally joins Indus 10 Km below Makhad. Korang River originates near Ghora gali, flows along Murree – Rawalpindi road and joins the Soan River near Sihala. Rawal Dam is constructed on Korang River. At higher elevations snow accumulates in the winter season and melts in summer that form small streams which eventually meet the main rivers of the area. Furthermore, monsoon rains generate heavy run-off which flow down the valley and the mean annual rainfall is 1435 mm. Considering the topography, rainfall regime, extensive catchment area and other hydrological conditions such as stream-flow rate, low silt inflow, availability of spillway sites, provision of large storage capacity and rocky basin, Rawal Dam was constructed in the past and is part of the water control infrastructure of Pakistan. This reservoir is designed to store surface water and ensure supply of drinking water to the dwellers of the area. Hydrological Modelling was carried out to better assess this catchment. Moreover, temperature and precipitation trend analysis were also performed on this catchment. Water availability of this catchment was also checked.