Journal of Advanced Civil and Environmental Engineering Vol.6, No.1, 2023, pp 33-41 ISSN: 2599-3356 DOI: http://dx.doi.org/10.30659/jacee.6.1.33-41 Journal of Advanced Civil and Environmental Engineering 33 Use of Hec-Ras Software to Analyze Floods in Joyoakan Urban Village, Surakarta City, Central Java Sigit Riswanto 1* and Mahdika Putra Nanda 2 1 Universitas YAPIS Papua, Jl Dr. Sam Ratulagi No 11, Trikora, Jaya Pura Utara, Kota Jayapura, 99113, Indonesia 2 Universitas Wiralodra, Jl. Ir. H Juanda KM.03 Karanganyar, Indramayu, 45213, Indonesia * Corresponding author: sigitriswanto@uniyap.ac.id (Received: 6 th January 2023 ; Revised: 21 st April 2023 ; Accepted: 17 th May 2023) Abstract: One of the natural phenomena that threaten the existence of human life in several regions in Indonesia every time the rainy season begins is flooding, one of which occurs in the Joyoakan sub-district in Surakarta City. Topographically, it is in a hollow area (under the main road), making it easier for water to enter the area. This is what makes the Premulung and Kaliwingko rivers unable to accommodate rainwater discharge and additional rainwater shipments from the Boyolali and Sukoharjo areas. The purpose of this study is to determine how much volume of inundation in the drainage canal can be reduced in the Joyoakan area and the appropriate efforts to deal with the inundation that occurs. The method used is descriptive research, to provide an overview of the variables studied and modeling using the HEC-RAS software. The result of the calculation is that the potential for inundation that can be reduced by the drainage channel is at the Q5 return period of 6,842.577 m3, the Q10 return period is 6,962.517 m3, and at the Q25 return period is 7,100.448 m3, while the results from the channel dimension modeling analysis, there are still puddles at several points, the right alternative in overcoming inundation is the need to revitalize the drainage channels by increasing the capacity of the drainage dimensions from the current size and improving the base slope of each channel and installing pumps as a means of control in accelerating water discharge. Keywords: inundation; flood tracing; drainage channels; HEC-RAS modelling 1. Introduction Floods are one of the natural disasters that most damage infrastructure, hamper agriculture, animal husbandry, and industrial production, and greatly affect all aspects of human life. [1]. The very significant impact of floods on society in the last decade has caused more than 400 billion USD in damage affecting millions of people around the world [2]. Floods are theoretically caused by the volume of water in a body of water such as a river or lake overflowing and then overflowing from a dam so that water escapes from the river and inundates the land, factors such as the size and nature of the rivers in and around the river. The water level downstream also determines whether or not flooding occurs in that area [3] The risk of global flooding is expected to increase further due to climate change and urbanization, especially in Asia and Africa [4]. The impact of flooding can cause damage to community settlements if water overflows settlements. Joyoakan Urban village is one of the urban villages in Surakarta City which is topographically located in a basin area (under the main road) which makes it easier for water to enter the area. This is what