Absence of reliable hydro-climatic information is among the bottlenecks for inadequate and improper management of stormwater runoff in rapidly-urbanizing catchments.This paper explores the influence of catchment heter...Absence of reliable hydro-climatic information is among the bottlenecks for inadequate and improper management of stormwater runoff in rapidly-urbanizing catchments.This paper explores the influence of catchment heterogeneity in understanding the proneness of urban catchments to stormwater-borne hazards.Using GIS techniques,satellite images,and field surveys,geomorphological features and hydrologic characteristics of the Mbezi River catchment in Dar es Salaam-Tanzania were modeled to understand variations in their influence on flood hazards occurrence throughout the study catchment.The findings reveal that with GIS techniques public,domain Digital Elevation Models(DEMs)can provide preliminary but useful insights to inform stormwater management decisions in cities with limited hydrological data.Specifically,the heterogeneity characterization of the case study catchment indicates that Mbezi River is fernleaf-shaped:it has a well-drained catchment(drainage density=1.9 km/km^(2)),with total relief and elongation ratios of 265 m and 0.25,respectively.Results further revealed that the catchment is comprised of many natural sinks(blue spots)that,upon enhancement,can retain about 18 percent of stormwater runoff that could otherwise contribute to downstream runoff challenges.About 68 percent of the major sinks(with potential volume>2.4 m3)are located along the river flood plain where land is publicly owned.Additionally,more than 11.6 ha of land(as property)and 168 buildings are in areas that were mapped to have large natural sinks and they are at risk to flooding when the sinks get filled.展开更多
文摘Absence of reliable hydro-climatic information is among the bottlenecks for inadequate and improper management of stormwater runoff in rapidly-urbanizing catchments.This paper explores the influence of catchment heterogeneity in understanding the proneness of urban catchments to stormwater-borne hazards.Using GIS techniques,satellite images,and field surveys,geomorphological features and hydrologic characteristics of the Mbezi River catchment in Dar es Salaam-Tanzania were modeled to understand variations in their influence on flood hazards occurrence throughout the study catchment.The findings reveal that with GIS techniques public,domain Digital Elevation Models(DEMs)can provide preliminary but useful insights to inform stormwater management decisions in cities with limited hydrological data.Specifically,the heterogeneity characterization of the case study catchment indicates that Mbezi River is fernleaf-shaped:it has a well-drained catchment(drainage density=1.9 km/km^(2)),with total relief and elongation ratios of 265 m and 0.25,respectively.Results further revealed that the catchment is comprised of many natural sinks(blue spots)that,upon enhancement,can retain about 18 percent of stormwater runoff that could otherwise contribute to downstream runoff challenges.About 68 percent of the major sinks(with potential volume>2.4 m3)are located along the river flood plain where land is publicly owned.Additionally,more than 11.6 ha of land(as property)and 168 buildings are in areas that were mapped to have large natural sinks and they are at risk to flooding when the sinks get filled.
