Integrated Modeling of Land and Water Resources in Two African Catchments

Seleshi Yalew, Seleshi Getahun Yalew

• Publisher: CRC Press
• Year: 2018
• Print ISBN: 9781138593381
• eBook ISBN: 9780429951947
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Environmental Science
• Index: Biological Sciences

Demand for land and water for agriculture, urbanization, irrigation, hydropower, and industrialization is increasing to meet the demands of growing populations and of growing economies. However, changes in land and water resources are often studied separately. A better representation of the interaction between land-use change and its drivers on the one hand and water resources on the other is imperative for sustainable environmental management.

This research investigates and develops spatial analysis methods and tools for the quantification of dynamic feedbacks between land-use change and water resources, by focusing on case study catchments in Ethiopia and South Africa. Furthermore, the research investigates methods for analysing land-use suitability and modelling land-use change. Results show that major changes in land-use have been observed in the past two to three decades in the study catchments. Model representation of the interaction between land-use change and water resources shows that changes in land-use influence hydrologic responses. These influences are especially pronounced during high- and low-flow seasons. Likewise, hydrologic processes and water resources availability influence land-use suitability and hence land-use change responses. Accounting for the dynamic feedback between land-use and hydrology thus produces improved knowledge that can better inform integrated natural resources management.

TABLE OF CONTENTS

Summary

Chapter 1. Introduction

1.1 Background

1.2 Integrated Assessment Modeling

1.3 Study Areas

1.4 Problem Descriptions

1.5 Research Objectives

1.6 Methodology

1.7 Structure of the thesis

PART I Land-Use Change Modeling

Chapter 2. Land suitability assessment in the Abbay basin

2.1 Introduction

2.2 Study Area

2.3 Materials and Methods

2.4 Results

2.5 Discussion

2.6 Conclusion and recommendations

Chapter 3. A web-based framework for land-use suitability assessment

3.1 1. Introduction

3.2 Data and Methods

3.3 Results and discussion

3.4 Conclusion

Chapter 4. Land-use change modeling for the Abbay basin

4.1 Introduction

4.2 Materials and methods

4.3 Results and discussions

4.4 Conclusion and recommendations

PART II Feedback between Land Use and Hydrology

Chapter 5. Modelling hydrologic impacts of semi-dynamic land use in the jedeb

5.1 Introduction

5.2 Existing literature: State-of-the-art

5.3 Materials and methods

5.4 Results and discussion

5.5 Discussion

5.6 Conclusion

Chapter 6. Feedback between coupled land-use and hydrologic models

6.1 Introduction

6.2 Study area

6.3 Materials and methods

6.4 Results

6.5 Discussion

6.6 Conclusions

Chapter 7. Conclusions and Recommendations

7.1 Conclusions

7.2 Recommendations

7.3 Limitations

References

Appendices

Appendix 1. WFlow model parameters

Appendix 2. Scenario Simulation

Appendix 3. SWIM output to SITE input converter

Appendix 4. Land-cover classification on GEE:code snapshot

Samenvatting

About the Author

Publications

LIST OF FIGURES

Figure 1-1. Location map of the Jedeb catchment and the Abbay basin in Ethiopia

Figure 1-2. Location and topographic map of the study area

Figure 2-1. The Abby basin and its sub-basins

Figure 2-2. Process diagram of the methods

Figure 2-3. (a) Slope and (b) elevation maps of the Abbay basin

Figure 2-4. (a) Soil depth and (b) soil water content in the Abbay basin

Figure 2-5. (a) Soil types and (b) soil stoniness in the Abbay basin

Figure 2-6. Distances to (a) town (b) water sources and (c) road in the Abbay basin

Figure 2-7. (a) Reclassified land cover and (b) protected areas in the Abbay basin

Figure 2-8. Constraint layers

Figure 2-9. Agricultural land suitability in the Abbay basin excluding constraint layers

Figure 2-10. Agricultural land suitability in the Abbay basin with constraint layers.

Figure 2-11. The Jedeb catchment in the Abbay basin (a,b); suitable agricultural land of 2009 (c), and reference agricultural land cover map of 2009 (d).

Figure 2-12. Spatial difference between the reference and the suitability maps for agricultural land-use of 2009

Figure 3-1. Conceptual framework of AgriSuit

Figure 3-2. Raster data layers used for the weighted overlay analysis

Figure 3-3. Sequence diagram of AgriSuit execution

Figure 3-4. OGR virtual format connecting QGIS and GFT. Note that ‘email’ should be Google authorized Gmail account.

Figure 3-5. Pair-wise comparison of suitability criteria on webAHP

Figure 3-6. GEE coding and visualization interface

Figure 3-7. Weighted averages (suitability weights) computed using webAHP

Figure 3-8. Web-client: the graphical user interface for the AgriSuit framework

Figure 4-1. Location and topographic map of the Jedeb catchment in the Abbay basin, Ethiopia

Figure 4-2. Software details of the system and application domain; modified from Mimler and Priess (2008)

Figure 4-3. Observed land-use maps of (a) 1986 and (b) 2009.

Figure 4-4. Changes between (a) observed maps of 2009 and 1986

Figure 4-5. Simulated land-use maps of (a) 2009 and (b) 2025

Figure 4-6. Difference map of (a) observed and simulated maps of 2009 and (b) simulated maps of 2009 and 2025

Figure 5-1. Location and topographic map of the Jedeb catchment in the Abbay (Upper Blue Nile) basin, Ethiopia

Figure 5-2. Overview of the different processes and fluxes in the WFlow model (Schellekens, 2014)

Figure 5-3. Simulated land-use maps of 1989 (a) and 2012 (b).

Figure 5-4. Soil groups in the Jedeb catchment

Figure 5-5. Catchment delineation in WFlow: (a) digital elevation map (DEM) (b) stream order as a result of computation of flow accumulation (c) burn-in of river network (d) resulting sub-catchments

Figure 5-6. Model calibration (1989-1993)

Figure 5-7. Model validation (1994-1998)

Figure 5-8. Observed vs. simulated discharge; the part in the ‘blue-box’ is further explored in Figure 9.

Figure 5-9. A closer look at observed and simulated flows with semi-dynamic and static land-use maps

Figure 6-1. Setup of hydrotope units in SWIM

Figure 6-2. Conceptual framework of the coupling

Figure 6-3. The Model coupling execution flowchart

Figure 6-4. Calibration and validation of the uncoupled hydrologic model

Figure 6-5. Comparison of coupled, uncoupled and observed flow 2001-2010

Figure 6-6. A closer look of the coupled and uncoupled flow simulations (2001-2002)

Figure 6-7. Reference map of 2010 (a), and simulated maps of 2010 from the uncoupled (b) and the coupled (c) models.

Figure 6-8. Land cover changes: 1990-2010

Figure 6-9. Trends in grassland biomass and grazing ecosystem services using the coupled and the uncoupled models

Figure A.1. Total grassland vs. sustainably graze-able grassland using the coupled model

LIST OF TABLES

Table 2-1. Data and data sources

Table 2-2. Slope classes for agricultural suitability

Table 2-3. Soil characteristics and suitability for agriculture

Table 2-4. Proximity influences on agricultural land suitability

Table 2-5. The fundamental scale for pair-wise comparison matrix (Saaty 1980)

Table 2-6. Inputs to the AHP for the pair-wise comparison analysis and computation of weights

Table 2-7. Indices computed using the GIS based AHP tool

Table 2-8. Summary of agricultural land suitability map of the Abbay basin

Table 2-9. Summary of land suitability for agriculture in catchments of the Abbay basin [km2 (%)]*

Table 2-10. Observed agricultural land-use vs. suitable agricultural land in the Jedeb catchment for 2009

Table 3-1. Data and data sources

Table 4-1. Data inputs and potential land use change drivers

Table 4-2. General demand estimations based on Mengistu (2006) and Jayne et al (2003)

Table 4-3. Land-use conversion matrix (1986-2009): conversion between land-use classes in km2 and percentage of total area (in brackets).

Table 4-4. Summary of significant correlations between land use and driving forces

Table 4-5. Factor loadings after varimax rotation and communality estimates (loadings >0.7 are in bold)

Table 4-6. Land-use suitability rule-sets

Table 4-7. Map comparison indices for the simulated and observed land-use of 2009

Table 4-8. Land-use conversion matrix (2009-2025): total area of conversion between land-use classes in km2 and percentages (in brackets)

Table 5-1. Record of daily hydro-meteorological data in the Jedeb catchment

Table 5-2. Comparison of simulated and reference land-use maps for the years 1989 and 2009

Table 5-3. WFlow model performance with static vs. semi-dynamic land-use inputs

Table 5-4. Overall average comparison of the simulated and observed flows (% difference) from 1999-2012

Table 6-1. Reductions in grazing capacity with distance from water. Source: Holechek et al. (1995)

Table 6-2. Reductions in grazing capacity for different slopes. Source: Holechek et al. (1995)

Table 6-3. Calibrated model parameters and their final values

Table 6-4. Coupled vs. uncoupled SWIM model performance against observed streamflow

Table 6-5. Overall average comparison with observed flow (% difference) from 2001-2010

Table 6-6. Comparison of simulated vs reference maps (GLC30) of 2010

Table A.1. 151First zone capacity

Table A.2. 152First zone saturated conductivity

Table A.3. 153First zone minimum capacity

Table A.4. 154Infiltration capacity of the compacted soil

Table A.5. 155Infiltration capacity of non-compacted soil

Table A.6. 156Decrease of saturated conductivity with soil depth

Table A.7. 157Manning’s roughness

Table A.8. 158Manning’s N for the river

Table A.9. 159Fraction of compacted area per grid-cell

Table A.10. 160Rooting depth

Table A.11. 161Residual water content

Table A.12. 162Water content at saturation

ACRONYMS

DEM	Digital Elevation Model
FAO	Food and Agriculture Organization
ha	Hectare
LULC	Land use/land cover
SRTM	Shuttle radar t...

Table of contents

• Cover
• Title Page
• Copyright Page
• Table of Contents