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GIS-Based Mapping of Erosion and Flood Sites in Gombe State

Gombe State Nigeria Erosion and Watershed Management Project (GM-NEWMAP), the implementing agency in the State, has the responsibility of providing a "Damage Control" to slow the expansion of targeted set of aggressive gullies across the State, thereby reducing the loss to property and infrastructure and helping cultivate community ownership; influencing the gully intervention to support integrated watershed management and move towards greater adoption of sustainable land and water management practices by local people in the sub-watershed where the gullies are located. Therefore, the purpose of this consultancy services is the Mapping of Gully Erosion/flood Sites and the generation of Land Resource Inventory data within a geographic information system (GIS) framework. This will aid in knowing the status of gully erosion sites and land resources in the state and effective management and monitoring of all erosion sites in the state. The mapping will also underpin project presentation and reporting on key status of erosion sites especially the sites for the NEWMAP GRASS component.


The scope of work includes the following:

  1. Identification of the sites affected by flood and erosion in the State through proper ground 'truthing' and/or field visits which involve appraisals, observations and measurements (sample/specimen collection).
  2. Generation of geological maps for erosion and watershed management
  3. Generate Land Resource Inventory (LRI) data such as soil/land suitability maps, for erosion and watershed/ catchment management.
  4. Mapping of land use land cover including the acquisition of necessary spatially referenced data of both primary source (such as attributes of selected sites, comprising of soil types, vegetation types and geo-ecological characteristics of the area in the state.
  5. Hydrological analysis for erosion and watershed management in the state
  6. Acquisition of spatial data of secondary origin, such as topographic sheets and satellite images with 0.5 spatial resolution and other records for the whole state.
  7. Development of spatial database that can be updated from time to time and subsequently, build a GIS for erosion and flood information management from the acquired primary and secondary data arising in (1) to (3) above.
  8. Conduct series of spatial analyses and modeling to produce map documents that can guide key policy and management decision making.
  9. Derivation of geo-database on the priority erosion and flood sites in the State
  10. Identification and delineation of major and minor watersheds in the State
  11. Identification of other potential areas prone to gully erosion and flooding in the State and the classification of the degree of vulnerability / risk potentials
  12. Assessment of the socio-economic impact of gully erosion and flood hazards on the people
  13. Present in easy to read maps: i. Spatial extent of erosion in the selected area ii. Spatial extent of flood affected area iii. Spatial analysis of socio-economic impacts iv. Predictive models of erosion and flood risk hazard based on anthropogenic, climatic and environmental factors v. Land Resource Inventory Map vi. GIS Catchment Management Plan vii. Soil Maps viii. Land use Land cover maps ix. Soil Suitability Map x. Geology maps xi. Map of a high resolution satellite image 0.5 covering the state

The consultant will be responsible for carrying out the detailed studies as contained in the ToR, which include the following:

  1. Spatial and Bibliographic Data Review
  2. Data acquisition and processing: i. Secondary data acquisition (Digital imagery, Topographic sheets, cadaster map) ii. Field Verification of acquired imagery iii. Acquisition of coordinates of prominent features and landmarks iv. Collection of randomly selected spot height v. Primary data acquisition vi. Data Capture vii. Data Analysis viii. Identification of floods plains and flood risk zones ix. Delineation of erosion maps
  3. Catchment management maps x. Buffers and Overlays

Further information: Gombe State Nigeria Erosion and Watershed Management Project (NEWMAP) Attn: Bala-dozen B. Nayaya State Project Coordinator Address: Opp. NNPC Depot, Near Dakrim Quest Hotel Tumfure, Gombe. Gombe State, Nigeria E-mail: Tel. 08089678732, +234 8052729656