The most conspicuous and dominant physical features are the numerous hills found in all parts of the city. The main hills are the headwaters of several rivers and streams that originate and radiate from the city, forming a natural drainage system with nine distinct catchment areas: Likhubula, Lunzu, Mombezi and Khombwi, which drain the northern part of the city, and Mudi, Chisombezi, Limbe, Luchenza and Mwampanzi draining the middle and southern parts. Because of the hilly topography, these natural drainage channels are narrow and have steep sides and gradients.