Cover Dynamics at the Wadla Delanta Massif, Northcentral Highlands - - PowerPoint PPT Presentation

The 4th Esri Eastern Africa Education GIS Conference 23 – 24 September, 2016 |UNCC, Africa Hall | Addis Ababa, Ethiopia

Detecting and Quantifying Land Use/Land Cover Dynamics at the Wadla Delanta Massif, Northcentral Highlands of Ethiopia

Nahusenay Abate PhD in Soil Pedology and Land Evaluation Samara University, Ethiopia

INTRODUCTION

• Various types of land covers are formed by either natural or

human or both factors over the last centuries (FAO, 2006).

• The effects of natural processes and human interventions are

facilitating ecosystem changes as the whole and land use/land cover (LU/LC) changes in particular.

• Some of the factors cause directly like forest destruction and
• thers merely enable the action of the former.

• Natural effects of LU/LC dynamics may be over a long period
• f time. For instance, climate change,
• Whereas the effects of human activities are being immediate

and often radical (Vlek, 2005)

• These changes cause great environmental uncertainty for:
• local and regional climate change,
• biodiversity loss,
• soil degradation and
• pollution of water, soil and air.

Continued ... Introduction

On the other hand, Farmers of the area do not use any cultural and/or chemical treatments to reclaim and maintain soil fertility

Continued … Introduction

• The rate, extent and intensities of human pressure on land are

absolutely greater than the previous time which affects status, properties and functions of ecosystems (Ellis and Pontius, 2007).

• LU/LC changes are a dynamic and complex phenomenon
• ccurring within the interface between human and ecological

systems

• All these have:
• a significant influence on natural ecological functions,
• a contribution of desertification and
• the global climate change

(Lambin, et al., 2003; Varallyay, 2010).

• Population

pressures accompanied with sedentary agriculture, settlement and sociopolitical instability have resulted in:

• substantial deforestation,
• loss of biodiversity and
• undesirable changes
• low agricultural productivity and
• food insecurity
• One of the major factors limiting agricultural development in

Africa in general and Ethiopia in particular is the lack of information on land use and land characteristics.

Continued … Introduction

Continued ... Introduction

• Topography also modifies the spatial variability of

 soil physicochemical properties,  soil water relationships,  soil textural composition,  soil forming processes and  their interaction with variable conditions (Tan et al., 2004)

• One of the immediate challenges facing in Ethiopia today is land

degradation, particularly loss of vegetation cover, soil quality and fertility as well as soil erosion.

• As with respect to geopedological approach, this can be related to three

levels, namely:

• landscape,
• relief form, and
• landforms (Prasad and Govardhan, 2011).
• Topography can affect:
• the potential land use systems through long term soil formation and

short term seasonal effects;

• soil nutrients through controlling soil water budgets, soil erosion and

deposition (Tsui et al., 2004 and Kumhalova et al., 2008)

Introduction …

Objective of the Study

• The general objective of this study was, therefore, initiated to

address the limited LU/LC change information in this region

• f the country at the Wadla Delanta Massif of northcentral

highlands of Ethiopia

• The specific objective:

To detect and quantify the spatial and temporal land use/land cover dynamics at the Wadla Delanta Massif

Location and Size of the Study Area

• The study area is found at the Wadla Delanta Massif northcentral highlands
• f Ethiopia which is located at:
• 11° 23’ 30.74’’ to 11° 50’ 52.45’’ N latitude and
• 38° 58’ 30.30’’ to 39° 27’ 44.78” E longitude
• which was mainly situated in plateau areas
• Altitudinal ranges from 1500 to 3819 meter above sea level (masl) at

the bottom of the valleys (Gosh Meda) and the tip of the mountain (Mekelet), respectively.

• It is placed about:
• 499 km to north of Addis Ababa, and
• 98 km to northwest of Dessie town, South Wello Zone

F 1. igurLocation map of the study area

Geomorphology and Topography of the Study Area

• The major landforms of the study area comprise:

 extensive plateaus with numerous convex hills, chains of hills with mountainous ridge, oval in shape with dendritic drainage pattern, river-valleys and very deep gorges at the boundary.

General Location …

MATERIALS AND METHODS

• For this study, different datasets were organized and used from satellite

imageries and topographic maps.

• ERDAS Imagine 10.0 and ArcGIS 10.2 software were utilized.
• Moreover, recently updated 1:50,000 topographic map was scanned,

geo-referenced and merged.

• additional point information and linear features (contours, roads and

rivers) were utilized.

• The Acquisition dates were chosen to be as closely as possible in the same

cropping season and from comparable climatic conditions.

Data Sources & Materials …

Table 1. Satellite Image Data Data type Sensor Acquisition date Spatial resolution Path/row Landsat MSS 1973-01-31 57 × 57 meter 168/52 Landsat TM 1995-01-05 30 × 30 meter 168/52 Landsat ETM+ 2014-01-21 30 × 30 meter 168/52

Data Sources & Materials …

• In parallel to the remote sensing work; field work was carried
• ut to collect data for Ground Control Points (GCPs).
• The field data were collected by measurements. During these

field trips, both GCPs and the Area of Interest (AOI) of study area were selected, demarcated and measured by Global Positioning System (GPS).

• To evaluate the accuracy of the classification system, 1020

reference test pixels were identified and confusion matrix was used. Confusion matrix indicates the nature

• f

the classification error.

• The accuracy assessment was performed for the 2014 LU/LC map

which was adopted by a stratified random sampling method.

• In this study, structured and semi-structured questionnaire

interview were administered to households living within the study area.

• The participants were taken from all topographic positions

(upper, middle and lower elevations). A total of 40 key informants were interviewed.

• They were nominated by the District Administrations who are

the ordinary farmers who lived in the area for longer period and had historic background about the area.

• Moreover,

the District Agricultural Office Experts and development agents were incorporated in this study.

Social Survey Methods

• The results of the study revealed that the forest and grazing

land covers over the years showed irregular trends (i.e. decrement and increment trends),

• As compared to the three consecutive periods (the 1973’s, the

1995’s and 2014):

• From 1973 to 1995, the forest and grazing lands showed

for the decrement trends but the agricultural lands increment, whereas

• from the 1995 to 2014 the trends showed that the forest

and grazing lands increment and the agricultural lands decrement.

• The increment of the forest land by 0.2%. This changes

might be due to the plantation program of Ethiopia over all the country.

RESULTS AND DISCUSSION

Continued …

• The shrub land showed that for all the three consecutive

years, regularly the decreasing trend,

• The bare land and riverbed (barren land) showed

frequent increment for all the consecutive years.

• The increment of bare land and riverbed from 1973 to

1995 were by 36 and 43%, and from 1995 to 2014 by 39 and 10%, respectively.

Results & Discussion …

• For the last four decades, the barelands/open spaces

were increased by 88% and riverbed by 57% of the total area (Table 3).

• This causes might be due to
• subsequent cultivation and
• the occurrence of repeated drought
• accompanied with unwise use of land resources,

which led to degradation of significant area of land

Results & Discussion …

Land use/cover 1973 1995 2014 Area Area Area Category km2 % km2 % km2 % Agriculture 356.97 33.78 375.92 35.57 345.37 32.68 Grazing land 89.81 8.50 53.12 5.03 80.95 7.66 Forest land 42.01 3.98 2.80 0.26 4.93 0.47 Shrub land 368.54 34.87 353.35 33.44 256.28 24.25 Bare land 181.78 17.20 246.32 23.31 341.56 32.32 Riverbed 17.67 1.67 25.27 2.39 27.69 2.62 Total 1056.78 100 1056.78 100 1056.78 100

Table 3. Area coverage of LU/LC classification (1973-2014)

Landsat-MSS image of land use/land cover in 1973

The 1st Landsat image false color composite before processing; The 2nd Landsat classified subset image; and The 3rd Area coverage and percentage of land use/land cover

Landsat-TM image

• f

land use/land cover in 1995

Landsat-ETM+ image of land use/land cover in 2014

• The results of the LU/LC analysis indicate that, in all the

periods, bare/open space and riverbed areas showed an increasing trend, while the rest showed decrements in area coverage.

• For the first time span period (1973-1995), the cultivated, bare

and riverbeds showed an increment, while the rest showed decrements.

• In the second time span (1995-2014), except for agriculture

and shrub lands, the rest showed increments

Extent, Trend and Rate of LU/LC Change

Table 4. Extent, trend and growth rate of LU/LC change in various periods (1973-2014)

Land use/cover Category 1973-1995 1995-2014 1973-2014 Area change Rate of change Area change Rate of change Area change Rate of change (km2) (km2/yr) (%)/yr (km2) (km2/yr) (%)/yr (km2) (km2/yr) (%)/yr

Agriculture 18.76 0.85 0.24

• 30.36
• 1.52
• 0.43
• 11.6
• 0.28
• 0.08

Grazing land

• 36.69
• 1.67
• 1.86

27.83 1.39 2.76

• 8.86
• 0.21
• 0.24

Forest land

• 39.21
• 1.78
• 4.24

2.13 0.11 4.00

• 37.08
• 0.88
• 2.15

Shrub land

• 15.2
• 0.69
• 0.19
• 97.09
• 4.85
• 1.45
• 112.29
• 2.67
• 0.75

Bare land 64.54 2.93 1.61 94.8 4.74 2.03 159.34 3.79 2.14 Riverbed 7.6 0.35 1.96 2.31 0.12 0.48 9.91 0.24 1.37

• In general, the rate of change in the first time span

period was faster and higher than the second time span.

• In the last four decades, more land was degraded and

abandoned, and the forest cover decreased.

• The
• verall

changes showed that the bare and riverbed areas were increased by 2.14 and 1.37% per year, respectively.

• The forests, shrub, grazing and to some extent the

cultivated lands were reduced by 2.15, 0.75, 0.24 and 0.08% per year, respectively. Continued … Extent, Trend and Rate of LULCC

• The overall accuracy showed that 88.43% with an overall

Kappa statistic of 0.8619 for Landsat 2014 ETM+ image.

• This means that 88.43% of the LU/LC classes are correctly

classified.

• The report derived from the accuracy assessment cell array shows

that the classification has resulted in more than 88% accuracy.

• In terms of producer’s and user’s accuracy, all classes were
• ver 83% accurate.

Validation of the Classification Results

Table 5. Accuracy assessment of the 2014 LU/LC classification

Land use type Agriculture Grazing Forest Shrub Bare Riverbed Row total CE UA Agriculture 169 11 6 5 191 11.52 88.48 Grazing land 8 145 3 12 6 174 16.67 83.33 Forest land 133 13 146 8.90 91.10 Shrub land 5 11 154 170 9.41 90.59 Bare land 2 6 159 10 177 10.17 89.83 Riverbed 8 3 9 142 162 12.35 87.65 Column total 192 165 144 170 186 163 1020 OE 11.98 12.12 7.64 9.41 14.52 12.88 PA 88.02 87.88 92.36 90.59 85.48 87.12

Causes of LU/LC dynamics

• Land use/cover changes are not only the cumulative effects of nature but

also results of a number of interacting variables and processes.

• The distribution of various LU/LC types are primarily controlled by:
• Natural factors (slope gradient, soil depth, terrain configuration,

drought and famine) and

• Anthropogenic factors-population pressure, land tenure, farming

systems and demand for sources of energy are among the major anthropogenic driving forces in the study area.

• Over the last four decades, significant change in land use/land cover has
• ccurred in the study area.
• The overall changes showed that the bare and riverbed areas increased,

while the forest, shrub, grazing and cultivated lands reduced in area coverage.

• The rate of change in the first period was faster and higher than the second

period.

• The major contributing factors include population pressure, land tenure,

incompatible farming system, and lack of alternative energy sources.

• An integrated approach should be followed in order to alleviate the current

constraints and ensure sustainable use of the limited land resources in the study area.

CONCLUSIONS

Thank You