The application of remote sensing and geographic information system (gis) in watershed analysis to d

AMINU ABDULWAHAB1, RAJI M. OLAYINKA2 AND GUNDIRI I. ABALIS3 Department of Surveying and Geoinformatics The Federal Polytechnic Mubi, Adamawa State.

ABSTRACT This research work focused on the application of remote sensing and Geographic information system (GIS) in watershed analysis to determine a suitable drainage pattern to minimize flood in Sabon-Layi ward of Mubi North LGA of Adamawa State. This research covers an area of approximately 0.2878sqkm. The digital Terrain Model (DTM) of the area was designed and produced using information acquired from Global Mapper Software package, also the contour map , Aspect map, Vector map and suitable drainage network map were produced using the following software packages ; Google Earth, ArcvGis 10.0, Suffer 8 and Global Mapper software. The result of the analysis shows the production of watershed for build-up area of Sabon-layi ward Mubi North LGA. The network of suitable drainage pattern was also produced from the analysis.

Keywords: GIS, DTM, DEM, Flooding

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INTRODUCTION Among the various natural resources that exist on this our planet (Earth), land is one of the basic natural resource that requires a total preservation and management for the sustainable survival of the survivors on it. Some of the factors that bring about land degradation include both human and natural factors such as; Poor settlement pattern, flooding, desertification, erosion, poor refuse disposal etc. This research work primarily focused on the impact of flooding and erosion and the means of solving the problem using the application of remote sensing and Geographic information system (GIS) to study the watershed analysis of the area to determine the selection of suitable drainage pattern.

Watershed analysis refers to the process of using Digital Elevation Model (DEM) or Digital Terrain Model (DTM) and raster data operation to delineate watershed and to derive topographic features such as stream and drainage networks.

Traditionally, watershed boundaries are drawn manually on a topographic map. The analyst then uses topographic features on the map to determine where a divide is located. Today, computer programs (software packages) are widely used to derive watershed from DEM or DTM, using computer technology we can generate preliminary watershed boundaries in just a fraction of time.

Since watershed is an area that drains surface water to a common outlet, then the delineation of watershed can take place at different spatial scale (Band et al, 2000). A large watershed may cover an entire stream system and within the watershed system, there may be smaller watersheds, one for each tributary in the system.

In most part of the world, especially in the developing countries, the problems of flooding and erosion are rapidly growing. Rainfall is seen as a major cause of flooding, (Akintola, 1978). He 2

however, includes human interference as being a joint causative factor. Flooding result when run off stream inflows make a steam full to capacity, and also to low infiltration capacity etc.

Hence, there is the need to explore new approaches in solving these peculiar flood problems by employing watershed analysis through the use of remote sensing and GIS. STATEMENT OF RESEARCH PROBLEM Sabon-layi is a ward within Mubi north LGA of Adamawa state Nigeria, which often experiences environmental degradation, this happen as a result of many factors, among which include unplanned layout, inadequate drainage patterns etc. Sabon-layi as one of the major ward in Mubi north LGA has only one drainage system that convey water to river Yadzaram which makes the lower level of the area to be water logged and marshy. The mere factor that affects the area remained water logged for a certain period of time and creates some problems like enormous damage to roads and housing in the area. This has always being a problem to people residing in the area from coming in or going out of the area especially after a heavy rainfall. Thus with good planning of drainage system within and around the area will really minimize the flood problem.

AIM AND OBJECTIVES This research work is aimed at selecting suitable drainage pattern to minimize the effect of flooding in the study area (Sabon Layi) using Watershed analysis. This can be achieve through the following objectives 1. Design of the digital Terrain model (DTM) of the study area.

2. Designing of the suitable drainage pattern based on the watershed analysis.

3. Delineation of the watershed of the study area based on the slope and area.

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aspect map of the study

STUDY AREA The research work covers Sabon Layi ward in Mubi North local government area of Adamawa state. Sabon-Layi lies between Latitude 10 16 05 and Longitude 13 16 17. The total area covered is 0.2878sqkm.

SIGNIFICANT OF THE RESEARCH WORK Sabon-layi is a residential and commercial area; that has influx of people coming in and going out on daily bases. But the issue of flooding has continue to serve as a major setback to the people residing in the area, especially those residing within the lower part of the area. During the raining season, water overflows in to houses and even to rooms of some residence especially those residing within the lower elevation of the area thereby creating large scale damage to properties and sometimes causes water borne diseases such as cholera epidemics which can easily lead to lost of lives.

It is hoped that with these research work, the above mentioned problems can easily be solved.

METHODOLOGY This research work was based on application of Remote Sensing and GIS in solving environmental hazards particularly flooding and erosion. Watershed analysis was used in GIS environment to undertake suitable drainage pattern based on the nature of the terrain. Whereby, the DTM used in this research work was generated using the data acquired from ASTER GDEM worldwide elevation data (1.5-ARC-second resolution).

The Hardware used for this research work include: Laptop computer with window7 package, printer and modem.

The software used for this research work include; Global mapper, Arcgis 10.0, Sufer8 and Google earth.

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DISCUSSION The contour and the suitable drainage pattern were generated from the DTM data obtained from Global Mapper software package.

The generated contour was then exported to .DXF format so that it can be accessed by other software packages such as Arcgis 10.0 and Suffer 8.

The Base map for this research work was obtained from Google Earth (Satellite imagery of year 2006).

The vector map showing the magnitude of flow direction was generated using sufer8 software package. The Slope and Aspect map were also generated using Arcgis 10.0 software packages.

RECOMMENDATION Based on this research work, the following recommendations were therefore made: a)

Watershed analysis is recommended for the determination of optimal drainage and

Suitable drainage patterns within the research area. b)

There is a need to come to the aid of the people residing within the research area by

constructing good drainage networks before the naturally eradicated drainages increase in number and in proximity. c)

Planned layout design should be encouraged to avoid negative effects of the unplanned

layout. d)

It is recommended that watershed analysis should be carried out on our various lands

before embarking on further planning.

CONCLUSION

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This research work was carried out using the application of remote sensing and GIS software packages whereby, various maps were produced such as; the DTM map, base map, watershed map, slope map, aspect map, vector map, vector overlay and the contour overlay map of the research area to determine the Suitable drainage network. The drainage pattern was overlay on the digital terrain model (DTM) to show how suitable the drainage network was on the natural ground surface.

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REFERENCES

Adewus, H. G. (1990). Combating water erosion and flood in Adamawa State Weekly scope, Vol. 5 No. 133 page 10.

Charley, R. J. (1968). Introduction to physical hydrology. Methuen publishers, London.

Furniss, Mike; McCammon, Bruce. (1993). A federal agency guide for pilot watershed analysis, version 1.2. Portland, OR: Pacific Northwest Region, Forest Service, U.S. Department of Agriculture; 201 p.

Henry, A. A. (2005). GIS-Based Watershed Analysis and Surface run-off estimation using Curve Number (CN).Journal of Environmental Hydrology Musa, A. A. (2001). “Application of GIS in planning field�. A paper presented at the Department of Regional Planning, FUT, Yola.

Ray, H. H. (1999). Soils and Erosion. In Adebayo, A. A. and Tukur, A. L. Adamawa state in maps.

Department of Geography, FUT, Yola.

Simonovili, S. (1993). Flood control management by integrating with expert system; Hydrological and water resource management.

USDA [USDA Forest Service]. (1988). Cumulative off-site watershed effects analysis. Service Handbook (Section 2509.22, Ch. 20, July 1988). San Francisco, CA: Region 5 Regional Office, Forest Service, U.S. Department of Agriculture; 32 p.

Ward, R. C. (1978). Flood focal problems in Geography. A Geographic perspective. Mc. Millan press Limited London.

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APPENDICES

APPENDIX 1

BASE MAP OF SABONLAYI WARD MUBI NORTH L.G.A

APPENDIX 2

DIGITAL TERRAIN MODEL (DTM) OF SABONLAYI WARD MUBI NORTH L.G.A

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APPENDIX 3

WATERSHED MAP OF SABONLAYI WARD MUBI NORTH L.G.A

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APPENDIX 4

SURFACESLOPE MAP OF SABONLAYI WARD MUBI NORTH L.G.A

APPENDIX 5

SURFACEASPECT MAP OF SABONLAYI WARD MUBI NORTH L.G.A

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APPENDIX 6

VECTOR MAP OF SABONLAYI WARD MUBI NORTH L.G.A

APPENDIX 7

VECTOROVERLAY MAP OF SABONLAYI WARD MUBI NORTH L.G.A

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APPENDIX 8

CONTOUROVERLAY MAP OF SABONLAYI WARD MUBI NORTH L.G.A

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