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ISSN (o): 2249-3905 ISSN (P): 2349-6525| Impact Factor: 7.19 |

THE ROLE OF REMOTE SENSING IN ASSESSING AND MAPPING OF THE VULNERABILITY OF SOILS IN IMO STATE TO GULLY EROSION HAZARD

CHUKWU, KEVIN EJIKE Ph.D. Department of Geography and Meteorology,

Faculty of Environmental Sciences

Enugu State University of Science and Technology (ESUT), Enugu State

Abstract

This work deals with the mapping of the vulnerability of soils in Imo State to gully erosion hazard using remote sensing. The main objectives of the study are to assess and map the vulnerability of some parts of Imo State to gully erosion hazard using remote sensing techniques. The DEM was generated and used to prepare slope map, elevation map and hill shading map. Results from the study show that 45.4 % of the land cover of Imo State

representing 2256.7 Km2 is covered by light vegetation whereas 24.7 % of the land area

representing 1229 Km2 is covered by thick vegetation. A large percentage of the entire land

area (21%) representing 1046.3 Km2 is cultivated whereas 6.4% representing 319 Km2 is

built up with houses and infrastructure like roads and bridges. The area covered by thick vegetation (24.7%) is categorized under slightly vulnerable to stable. A larger percentage (45.4%) is covered by light vegetation, and therefore, classified as moderately vulnerable to erosion whereas 27.4% comprising cultivated and built up areas are classified as highly to

extremely vulnerable to erosion. Most parts of the state (4133Km2) representing 84% of the

entire landscape fall into slightly to less vulnerable to erosion with a slope class between 1 –

4% slope. However, 569.3 Km2 of land representing 12% of the land area are moderately

vulnerable to erosion whereas 4.5% of the entire land area is highly to extremely vulnerable to erosion with slope class of between 7- >12%. Therefore, it was recommended that a control system should be put in place using Remote Sensing applications. Control measures based on engineering structures is required, which includes the construction of terraces, waterways, concrete structures and porous barriers.

Keywords: mapping, vulnerability of soils, gully erosion hazard, remote sensing.

Introduction

Globally, environmental issues have become major concern to governments and citizens of various nations, including Nigeria. The environment, which is at the heart of economic, social, cultural and human activities, has been disrupted by man‟s neglect and abuse. Pollution, deforestation, soil erosion, landslides and global warming are the aftermaths of this abuse in the ecosystem. The issue of protection, mapping and monitoring becomes paramount in the face of the increasing population of residents in the southeast geopolitical zone of the country. They are severely impoverished, particularly, the rural dwellers due to environmental degradation and increasing population impact on the environmental resources. (Majid, Azlin and Said, 2012)

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(Ofomata, 1985; Igbokwe, 2004; Bawahidi, 2006). Agulu-Nanka in Anambra State is an area badly affected by water erosion. Up to 250 tonnes per hectare of soil have been lost in severe storms. Similarly, Asiabaka and Boers (1988) had estimated that over 1,970 gully sites occur in Imo and Abia States. A conservative assessment shows the distribution of known gully sites, in different stages of development are as follows; Abia (300), Anambra (700), Ebonyi

(250), Enugu (600), Imo (450) (Igbokwe et al (2003), Egboka (2004).

In Imo State, the impact of gully erosion has been unimaginable, displacing communities and causing destruction of farm lands. However, human activities like land-clearing, and deforestation, overgrazing, as well as the creations of firewood tracks accelerate the natural rates of these processes. The immediate site effect is the loss of soil while the off-site effects include the yield of sediment on the river network, which results in declining water quality and damage to the hydraulic structures. It is, therefore, necessary to assess and to manage areas that are vulnerable to gully erosion in order to mitigate any damage associated with it. Gullies are triggered by man‟s activities, rainfall erosivity and soil erodibility. Gully Erosion is, however, a prominent feature in the landscape of Imo State. The topography of the area as well as the nature of the soil contributes to speedy formation and spreading of gullies in the area. The need to predict gully occurrences has led to the development of numerous stochastic and process-based models, with increasing emphasis on the use of the Satellite Remote Sensing (SRS).

Statement of the Problem

In spite of technological advancement, erosion menace still remains a major problem in Nigeria, especially in South Eastern Nigeria. The yearly heavy rainfall has very adverse impacts altering existing landscape and forms. This creates deep gullies that cut into the soil. The gullies spread and grow until the soil is removed from the sloping ground leading to formation of head-ward erosion. The entire process results to drastic reduction of arable lands, economic trees, valuable properties, homes, lives and sacking of families. As a matter of fact, there is a direct correlation between development and the effect of gully erosion, the evaluation of this environmental hazard is important; hence the decision to carry out this research.

Aim and Objectives of the Study

The main aim of the study is to assess and map the vulnerability of some parts of Imo State to gully erosion hazard using remote sensing techniques.

The specific objectives which are designed to achieve the aim are:

1. To use remote sensing techniques to map the land use and management of Imo

State with a view to depicting the spatial distribution of gully erosion hotspots in Imo State.

2. To use remote sensing techniques to map vegetation and land cover of Imo State

with a view to depicting the spatial distribution of gully erosion hotspots in Imo State.

3. To use remote sensing technique to map topography and hydrology of Imo State

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LITERATURE REVIEW Remote Sensing

Remote sensing is broadly defined as collecting and interpreting information about an object without being in physical contact with that object. In a way our eyes keep doing „remote sensing‟ all the time but the eye‟s ability in this aspect is limited by three factors:

a. Our ability to see only within the very narrow range of visible light;

b. The limited distance up to which we can see an object clearly; and

c. Absence of a device within our body which can record and store the images scanned

by our eye in full (Abbasi and Abbasi, 2012).

We do have our memory (in which images get stored) and we also have the ability to draw pictures of what we see. But both these abilities are of limited use in handling large volumes of information. Aircraft and satellites are the common means to do remote sensing. These carry with them sensors capable of responding to a much wider range of electromagnetic radiation (light heat and radio waves) than our naked eyes can and forming images for subsequent interpretation. (Abbasi and Abbasi, 2012).

Literally, Remote Sensing means obtaining information about an object, area or phenomenon without coming in direct contact with it. If we go by this meaning of Remote Sensing, then a number of things would be coming under Remote Sensor, e.g. Seismographs, fathometer etc. Without coming in direct contact with the focus of earthquake, seismograph can measure the intensity of earthquake. Likewise without coming in contact with the ocean floor, fathometer can measure its depth. However, modern Remote Sensing means acquiring information about earth‟s land and water surfaces by using reflected or emitted electromagnetic energy.

Remote sensing technologies are used to gather information about the surface of the earth from a distant platform, usually a satellite or airborne sensor. Most remotely sensed data used for mapping and spatial analysis is collected as reflected electromagnetic radiation, which is processed into a digital image that can be overlaid with other spatial data (Pullar & Springer, 2000).Remote sensing, in simplest terms, means viewing something from a distance rather than by direct contact. A handheld camera is an example of a remote sensing instrument. In terms of earth science, remote sensing refers to the ability of satellites to detect

electromagnetic radiation from features on the earth's surface or in the atmosphere. Solar

energy that reaches the earth is composed of many kinds of radiation, including light that is visible to people, thermal infrared, microwave, radar, and X-rays. Every substance with a

temperature greater than absolute zero (-273 degrees Celsius, or -459 degrees Fahrenheit)

emits some form of electromagnetic radiation. Some satellite sensors detect visible light reflected from the earth's surface or atmosphere, and others detect radiation emitted from the earth (Pullar & Springer, 2000). Satellites can easily measure sea ice in the visible, infrared, and microwave regions of the electromagnetic spectrum. However, there are advantages and disadvantages to each type of radiation. None of the spectral regions allow scientists to optimally view sea ice in all conditions. The following sections describe each region in more detail (Pullar & Springer, 2000).

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contact between the sensing organs and the external objects. In another word, we are performing Remote Sensing all the time. Generally, Remote sensing refers to the activities of recording/observing/perceiving (sensing) objects or events at far away (remote) places. In remote sensing, the sensors are not in direct contact with the objects or events being observed. The information needs a physical carrier to travel from the objects/events to the sensors through an intervening medium. The electromagnetic radiation is normally used as an information carrier in remote sensing. The output of a remote sensing system is usually an image representing the scene being observed. A further step of image analysis and interpretation is required in order to extract useful information from the image. The human visual system is an example of a remote sensing system in this general sense, (Sharma, Murali, Hemamalini and Rao, 1992). In a more restricted sense, remote sensing usually refers to the technology of acquiring information about the earth's surface (land and ocean) and atmosphere using sensors onboard airborne (aircraft, balloons) or space borne (satellites, space shuttles) platforms, (Sharma, Murali, Hemamalini and Rao, 1992).

The Remote Sensing Process

Scientists have been developing procedures for collecting and analyzing remotely sensed data for more than 150 years. The first photograph from an aerial platform (a tethered balloon) was obtained in 1858 by the Frenchman Gaspard Felix Tourna chon (who called himself Nadar). Significant strides in aerial photography and other remote sensing data collection took place during World War I and II, the Korean Conflict, the Cuban Missile Crisis, the Vietnam War, the gulf War, the war in Bosnia, and the war on terrorism. Basically, military contracts to commercial companies resulted in the development of sophisticated electro-optical multispectral remote sensing systems and thermal infrared and microwave (radar) sensor systems. While the majority of the remote sensing systems may have been initially developed for military reconnaissance applications, the systems are also heavily used for monitoring the Earth‟s natural resources (Jensen, 2007).

The remote sensing data-collection and analysis procedures used for earth resources applications are often implemented in a systematic fashion that can be termed the sensing process. The procedures in the remote sensing process are summarized here.

Statement of Data Data-to-Information Conversion Information The problems collection Presentation

The Remote Sensing Process

Source; Crisp (Centre for Remote Sensing & Processing, 2001)

 Statement of the problem: The hypothesis to be tested is defined using a specific type

of logic (e.g., inductive, deductive) and an appropriate processing model (e.g., deterministic, stochastic).

 Data collection: In Situ and collateral data necessary to calibrate the remote sensor data

and/or judge it‟s geometric, radiometric, and thematic characteristics are collected.

 Remote sensor data are collected passively or actively using analogue or digital remote

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Gully Erosion Studies

Quite a number of Gully Erosion studies have been done in affected areas of the south-eastern part of Nigeria. They were carried out to establish major causes of the gullies, effects and solutions to be undertaken to curb such processes.

Literature reviews for Gully Erosion to be discussed include:

(a) Performance of Gully Erosion Control Measures in South-Eastern Nigeria (b) Gully Erosion Monitoring in South-Eastern Nigeria

a) Performance of gully erosion control measures in South-eastern Nigeria

The performance of gully erosion control measures in some parts of south-eastern Nigeria is presented. The measures include tree planting, hydraulic regulation works that integrate a drainage network with storage ponds to cut off flood crests and lower hydraulic loads of interceptor canals, and stabilization works such as check dams on the main channels of gullies and wickerwork fences and hedges at the inner gully slopes. There is evidence that tree planting and surface regulation of surface waters is effective in controlling only shallow (15 m deep) gullies that have not cut through a saturated zone. These measures tend to fail when used for deep gullies that are greatly affected by groundwater especially when such gully floors are located in non-cohesive and very permeable sands. In the last quarter of the nineteenth century channels in some parts of Nigeria were noticed to have entrenched their valleys. These channels generally eroded into red-earth and unconsolidated geologic materials establishing prominent gullies with near vertical slopes. Increased erosion activities in the vicinity of the early gullies have continued to expand these gullies into a complex system. Some of the gullies especially those in south-eastern Nigeria are now of canyon proportion, and constitute the most threatening environmental hazard in this part of Nigeria. The most active and dangerous spots occur at Agulu, Nanka, Alor, Oraukwu, Oko and parts of Udi, Enugu and Ukehe in Anambra State. Other catastrophic gullies occur at Amucha, Njaba in Imo State Isuikwuato, Ohafia, Abriba and Arochukwu in Abia State, and in parts of Uyo in Akwa Ibom State and Calabar in Cross River State. In all these places, with similar stratigraphic sequences of thick cohesion less sand strata overlain by a red clayey sand stratum and surface earth of either sandy loam or silty loam, intense gullying involving sudden and often catastrophic movements of large earth masses, has sent villages packing, wrecked homes, swept crops and washed roads away. The incidents of gullying have caused much concern to successive governments of Nigeria and have generated much attention among institutional and private researchers. Studies have been conducted and seminars and workshops held on the immediate and remote causes of the gullies. Based on some of the results of these studies, a number of control measures have been designed and constructed in some of the affected areas. Some of these measures have been fully or partially successful while others have woefully failed.

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Causes of the Gullies

The causes of the intense gullying are evident from the results of the studies so far conducted in the area. From the much that has been postulated and written on the origin and development of the gullies, there appear to be a considerable measure of agreement. The table below summarizes the opinions of the main workers.

Summary of opinions of several workers regarding causes of gullying in the study area.

Source: Challenges in African Hydrology and Water Resources (Egboka, and Okpoko, 1984; proc. Harare Symposium. 1984), IAHS Publication no. 144 pp335- 347.

The earlier workers (Floyd, 1965; Ofomata, 1965; Ogbukagu, 1976; Technosynesis, 1978; Nwajide & Hoque, 1979) have emphasized the importance of the soil and geologic materials exposed by the removal of vegetation cover and the impact of heavy rainfall on such materials. The consensus of these earlier workers is that the high intensity rainfall in the area produces high volumes of overland flow with high erosive energy. The action of the highly erosive floods on the unusually susceptible geological and soil materials produces the complex gullies. Floyd (1965) had suggested a six-stage evolution of the gullies:

(a) Intense agricultural activity leading to soil degradation and destruction (b) Rain splash and removal of soil particles

(c) Leaching and eluviations (d) Sheet and rill erosion

(e) Accelerated erosion and formation of gullies

(f) Mass earth movements through slumping, sliding and downhill creep leading to the complex badlands.

More recently, the effects of-groundwater and hydro-geotechnical factors have been highlighted as possible additional factors especially in the most dangerous spots where mass earth movement is the dominant mechanism. (Egboka and Okpoko, 1984) and (Egboka and Nwankwor, 1985) indicated that the active gullies are located mostly at the discharge areas of groundwater systems. The high pore-water pressures especially during the peak recharge times of the rainy season reduce the effective strength of the unconsolidated materials along the seepage faces. It has also been shown (Uma & Onuoha, 1986) that, in some areas, the high seepage forces due to the near critical exit hydraulic gradients at the various levels of seepage on the gully walls produce boiling conditions, piping and internal erosion that undermine the bases and partial bases of the gullies.

Author(s) Causes of gullying

Floyd (1965) Soil characteristics and human activities

Ofomata (1965) Mainly soil characteristics, less of human

activities

Ogbukagu (1976) Mostly geologic set up and soil

characteristics

Nwajide & Hoque (1979) Topography, climate and soil characteristics

Egboka & Nwankor (1985) Mostly groundwater conditions and soil

characteristics

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One fact is clear from the several studies and from a close field inspection of the affected

areas; the development of the gullies is progressive through at least four main stages namely:

(a) Formation of rills,

(b) Development of incipient gullies,

(c) Formation of shallow gullies (<15 m deep), and (d) Development of deep gullies (>15 m deep).

The main erosional activity at the first three stages involves the surficial removal of soil grains and small chunks of earth by rain splash, concentrated flood run-off along the rills and existing gullies and minor undercutting at the toe of the channels. Some of the gullies tend to stabilize at or before the third stage. Those that develop up to the fourth stage constitute the most catastrophic cases. They frequently contain groundwater seepages and springs at several horizons of their slope and their bases are formed by a thick stratum of very cohesion less and permeable white sands. The dominant mechanism at this fourth stage is sliding, slumping and soil flow involving movement of large soil masses, (Egboka and Nwankwor, 1985).

RESEARCH METHODOLOGY Study Area

Imo State is one of the 36 states of Nigeria and lies in the south eastern part of Nigeria with

Owerri as its capital and largest city. The state is named after the Imo River.The main cities in

Imo State are Owerri, Orlu and Okigwe. The local language is Igbo and Christianity is the predominant religion, its citizens are predominantly farmers and artisan.

Location, Position and Size

It lies within latitudes 4°45'N and 7°15'N, and longitude 6°50'E and 7°25'E. It occupies the area between the lower River Niger and the upper and middle Imo River. Imo State occupies the area between the lower River Niger and the upper and middle Imo River. Imo State is bounded on the east by Abia State, on the west by the River Niger and Delta State; and on the north by Anambra State, while Rivers State lies to the south. Imo State covers an area of about 5,100sq km.

Imo State is underlain by the Benin Formation of coastal plain sands. This formation, which is of late Tertiary age, is rather deep, porous, infertile and highly leached. In some areas like Okigwe, impermeable layers of clay occur near the surface, while in other areas, the soil consists of lateritic material under a superficial layer of fine grained sand. Seven (7) geologic formations cover the study area, these are:

(1) Niger Delta Formation – consist of sands, gravels, clays mainly erinaceous with very low

dip structure to the SSW;

(2) Coastal Plain Sands Formation – consists principally of sands, gravels, clays, and shale‟s

(lignite‟s). Topographically, it consists of gently sloping plain;

(3) Bende Ameke Group Formation – lithology are clastic sedimentary rocks consisting

mainly of lignite conglomerates with interblended sandstones, and shale.

(4) Imo Shales Formation - consists of clay-shale with intra-formational sand bodies. It is

typified with lowland ridges.

(5) This formation is generally called The Plateau and Escarpment made up of three groups:

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sands, gravels, siltstones, sandstones and grits. The topography consists of minor cuesta, mesas and escarpment.

(6) This formation consists of – Asata-Nkporo Shale, Awgu-Ndeaboh Shale Group, Ezeaku

Shale Group, and Asu River Group. Lithologies are shale with lenticular sand bodies, thin

limestone‟s, and minor sandstone lenses with igneous bodies.

(7) Asu River Group Formation – consist of crystalline rocks, with topography of mountain

terrain with plan ted margins. Relief and Drainage

The type of geology and soil of an area plays an important factor in the development of gully erosion. Rivers are few with vast inter fluxes which are characterized by dry valleys that carry surface drainage in periods of high rainfall. The phenomenal monotony of the terrain may be accounted for by the absence of any tectonic disturbances and by the homogeneity of the rock structure (Udo, 1970).The main streams draining the state are Imo, Otamiri, Njaba and Ulasi rivers, all of which have very few tributaries. With the exception of Imo River, which runs through the area underlain by the Imo Shales other rivers rise within the coastal plain sands. Generally, river valleys constitute the major physical features, which are often marshy.

Climate and Vegetation

Rainfall: Rainfall is an important element of far reaching consequences to the problem of soil erosion. The period for rainy season is between April and October. The average annual rainfall of the study area is about 2300mm.Rainfall in the study area stops within the month of November while March is usually sporadic and only regularized from April with May to July as the climax. Heavy rains are also witnessed in September. The heavy rainfall of this period and its frequency which witnessed large run-offs from the residential, pavement and farmland areas are instrumental to the erosion phenomenon in the place.

Sunshine: Maximum sunshine hours are usually recorded in the dry months of January to

April and November to December, when the mean monthly maximum is about 6 hours. Lower values of about 2 hours are recorded for the wet months of May to October.

Temperature and Evaporation: Owerri West L.G.A have tropically dry and wet climate.

Average daily minimum temperature is about 19oC. Evapotranspiration is estimated at

1450mm per year.

Relative Humidity: Relative humidity is lower in the dry period of January to March and

November to December with values of about 95% for wet periods, the value increases up to 97% or more.

Population

According to 2006, National Population Commission Census (NPC) the population of Imo State is 4,800,000 million and using the population estimate of 2.5% annual increase the population of the area at the end of 2014 will be 4,920,000 million with a population density varies from 230-1, 400 people / sq. km. its population makes up 2.8% of Nigeria‟s total population.

Research Design

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Data Acquisition

The data collected for the study are classified into primary and secondary data. The primary data are coordinates of already existing gully sites obtained from GPS observations during reconnaissance survey of Imo State. Secondary data source includes information on rainfall distribution from January to December, 1982-2008 collected from records of NIMET. Existing road network, settlement distribution, administrative map, drainage patterns and vegetation/land use was obtained from ASTAL Uyo whereas geology, rainfall, relief, and soil maps printed and published by ministry of lands, survey and urban planning, Owerri, Imo state from 1980-date were collected. The elevation data (DEM) and contour map of Imo State for 2014 was derived from Advanced Space borne Thermal Emission and Reflection (ASTER).

Fieldwork

A reconnaissance survey was carried out in the study area to identify sampling points. Sampling points were chosen in each selected site using free survey technique (observation points that are representative of the site are chosen by the surveyors based on personal judgment and experience) (Mulla and McBratrey, 2000).

RESULTS AND DISCUSSION Political Map of Imo State

Imo state is politically divided into 27 local government area. The satellite imagery of Imo State is also presented below;

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Fig. 2. Satellite imagery of Imo State

(Source: Gear-Up Consult Limited Suite D5, Bethel Plaza, Okpara Avenue Enugu) Vulnerability of Imo State of Gully Erosion Hazard

Land Use and management

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including road networks. The area covering settlements and road networks are classified as highly vulnerable because human activities increase soil erodibility rates.

Vegetation and Land Cover of Imo State

Results from the study showed that 45.4 % of the land cover of Imo State representing 2256.7

Km2 is covered by light vegetation, whereas 24.7 % of the land area representing 1229 Km2 is

covered by thick vegetation. The result also showed that a large percentage of the entire land

area (21%) representing 1046.3 Km2 is cultivated whereas 6.4% representing 319 Km2 is built

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Fig. 3. Land use map of Imo State

(Source: Gear-Up Consult Limited Suite D5, Bethel Plaza, Okpara Avenue Enugu) Topography and Hydrology of Imo State

Imo State‟s topography consists of high altitudes and rugged landscapes, as described earlier. The rugged topography and steep slopes affect soil erosion rate through its morphological characteristics. Two of these, namely gradient and slope length, are essential components in quantitative relationships for estimating soil loss (Wischmeier and Smith 1978). Results of the

study show that most parts of the state (4133Km2) representing 84% of the entire landscape

fall into slightly to less vulnerable to erosion with a slope class between 1 – 4% slope.

However, 569.3 Km2 of land representing 12% of the land area are moderately vulnerable to

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slope class of between 7- >12%. These results concur with that on Fig.4.8 showing analysis of hill shading for Imo state which showed that 87% of the area shaded fall within the highest heights of 176 – 187m and above whereas the remaining part (13%) fall within heights lower than 176m. Hill shading is the shadows drawn on a map to simulate the effect of the sun's rays over the varied terrain of the land. It is a hypothetical illumination of a surface according to a specified azimuth and altitude for the sun. Hill shading creates a three-dimensional effect that provides a sense of visual relief for cartography, and a relative measure of incident light for analysis.

Summary of Findings

Results show that most of the soils in the study (79.9 %) are classified as highly to moderately vulnerable to erosion based on the RUSLE soil erodibility classification. This means that the combined effect of cultivation (33%), light vegetation (37.2%) and human settlements (9.1%) combine to expose the soils to greater risk of gully erosion. Thus 80% of the soil of Imo State will be classified as highly vulnerable to erosion. However, the total percentage area under thick vegetation is 18.3% and this area fall under slightly vulnerable classification. The natural vegetation protects the soil against the impacts of rainfall and it is a source of organic matter to the soil. These factors improve infiltration and enhance the recharging of groundwater reservoirs. When vegetation cover is displaced, infiltration capacity is decreased, resulting in surface runoff, which will carry sediments and nutrients into rivers (Van Oost et al., 2000; Zuazo and Pleguezuelo, 2008).

Conclusion

Technological advancements in the world today have led to better, efficient and effective techniques of information management. From time to time a lot of information is being generated about earth resources and effect of human activities on these resources, thus creating a need for managing and planning. The use of Remote Sensing techniques will help greatly in the acquisition, organization, management and analysis of these large volumes of data, allowing for better understanding of natural disasters and the importance of record keeping for future use.

Recommendations

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References

Asiabaka, C. C. and Boers, M. (1988). An Analysis of the Existing Traditional methods of

Farming and Erosion Control among Farmers in SE Nigeria. Report of the Erosion

Research Centre, FUTO, Owerri, Nigeria.

Ayeni O. O., Nwilo P. C., Badejo O. T. (2004) “Application of Nigeria- Sat1 in monitoring

erosion along Lagos Coast line” www.google.com/nwilo.htm

Bawahidi, K. S. Y. (2006) Integrated land use change analysis for soil erosion Phd Thesis,

University Sains Malaysia.

Cihlar, J. & Jansen, L. J. M. (2001) from land cover to land user: A methodology for

efficient land use mapping over large areas. Professional Geographer, 53, 275-289.

Egboka, B. C. E. (2004). Distress Call and Plea to the Senate Committee for Urgent

Actions against Floods, Soil/Gully Erosion/ Landslides Disasters in the Southeast.

Paper Presented to Senate Committee on Environment: Roads/Erosion Senate Delegation to the Southeast. 30p.

Egboka, B.C.E. & Nwankwor, G.I. (1985) “The hydro-geological and geotechnical parameters as causative agents in the generation of erosion in the rainforest belt of Nigeria” J. Afr. Earth Sci. 3(4), University Press 417-425.

Egboka, B.C.E. & Okpoko, E.I. (1984) “Gully erosion in the Agulu-Nanka region of

Anambra, Nigeria”. In: Challenges in African Hydrology and Water Resources

(procHarare Symposium. 1984), IAHS Publication no. 144 pp335- 347.

El-Swaify S. A. (1997). Factors affecting soil erosionhazards and conservation needs for

tropical steep lands, Soil Technology, 11 (1) 3-16

Lal, R., J.M. Kimble, R.F.Follett and B.A.Stewart (Eds) 2001. Assessment Methods for Soil

Carbon. CRC/Lewis Publishers, Boca Raton, FL, 676 pp.

Majid Moradmand, MD Azlin and MD Said, (2012) Soil Erosion Modelling in Tropical

Watersheds. School of Civil Engineering, University Sains Malaysia, 2012.

Nwajide, S.C. and Hoque, M. (1979) "Gullying processes in south-eastern Nigeria", Nigeria

Field. Pp64:64-74

Pullar, D. & Springer, D. (2000). Towards integrating GIS and catchment models.

Environmental Modelling and Software, 15, 451-459.

Sharma V.V.L.N, Murali Krishna G., Hemamalini B. and Rao K. N., (1992) LU/LC Change

detection through Remote Sensing and its climatic implications in the Godavari

delta region-Journal of Indian Society of Remote Sensing. 29 (1&2)

Tasneem Abbasi, and SA Abbasi (2012).Design and performance evaluation of the imaging

payload for a remote sensing satellite Optics & Laser Technology, Volume44,

Figure

Fig. 1. Administrative Map of Imo State from NigSat1 (Source ASTAL Uyo)
Fig. 2. Satellite imagery of Imo State
Fig. 3. Land use map of Imo State

References

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