INVESTIGATION OF DRAINAGE IN URBAN AREA USING GEOGRAPHIC INFORMATION SYSTEM IN THE CASE OF NEKEMTE TOWN

Abstract

Drainage is an important aspect of the urban, rural, forest, and agricultural environments as it aids in the removal of excess water volume. In Nekemte town, where this study is conducted, different drainage problems are encountered in different places. Most drainage structures built in this area were built without a thorough drainage investigation, causing a slew of issues for the people who lived there, particularly during the rainy season. The problems that increase the drainage problems from time to time in Nekemte town were caused by the illegal use of drainage structures (components) like pipes, culverts, and ditches, and their consequence is the overflow of water because of illegal waste (solid waste) in the drainage lines. The objective of this study was to investigate drainage problems using ArcGIS software in the case of Nekemte town. To achieve this objective, a digital elevation model of the area was created from contours. Different hydrological patterns were developed using the ArcGIS hydrology tool and combined with other tools to identify cross-drainage requirements. In the study area, there are ten (10) watersheds and an outlet (pour point). Three (3) stream orders exist in the study area. Protected areas are those that are at least fifty (50) meters from the stream network. The watershed, road (current and proposed), low drainage density, and stream order are all considered when calculating an area’s cross-drainage requirement. In the study zone, there are cross-drainage requirements in twenty (20) different places. Seventeen (17) of those cross-drainages lead to exits in the protected zone. The discharge of the area is also computed using the rational method. In general, this study found that cross drainage between Wollega and the stadium is inadequate and improperly placed.