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CHAPTER 2 AN OVERVIEW OF THE ULUGURU WATER CATCHMENTS
Introduction
This chapter begins by defining water catchment. It further describes the Uluguru water catchment by providing details of the geographical location, topography, vegetation and hydrological distribution. It follows by providing a detailed view of the ecological, hydrological and economic importance of the water catchment. The chapter also provides a detailed review of the current state of the catchment deterioration, its impact on downstream users of ecosystems from the catchment, and efforts to combat the deterioration. The chapter ends with a conclusion on the matters raised in the chapter.
Definition of water catchment
Defining water catchment has always been difficult in all sciences related to the natural world (Harte, 2002). The difficulties in defining water catchments arises partly from our inability to ‘see’ the subsurface of a catchment, in which much of the hydrologic processes remains hidden from our current measurement techniques (Beven, 2000). This is due to the fact that the water catchments are self-organised systems, whose form, drainage network, ground and channel slopes, channel hydraulic geometries, soils, and vegetation, are all a result of adaptive ecological, geomorphic, and land-forming processes (Sivapalan, 2005). These difficulties have resulted in different definitions of the term water catchment. For example, the Department of Environmental Protection of New Jersey, USA, defines a water catchment as an area of land, separated from others by high points that are either hills or mountains, that drain into a body of water such as a river, lake, stream or bay (Wagener et al., 2007). It includes not only the waterway itself but also the entire land area that drains into a water body (Wagener et al., 2004).
The Watershed Atlas (WA) defines water catchment as a basin-like landform defined by highpoints and ridgelines that descend into lower elevations or stream valleys (WA, 2012). The landform carries the water “shed” from these lands after rain falls and snow melts, and channels it either as surface water (mainly streams), groundwater, and creeks making its way to larger rivers and eventually the sea (OECD, 2005). Water catchments have also been defined in many ways by hydrologists. For example, Sivapalan (2005) defines a water catchment as the drainage area that contributes water to a particular point along a channel network (or a depression), based on its surface topography. Wagener et al (2004) define water catchment as a landscape element that integrates all aspects of the hydrologic cycle within a defined area that can be studied, quantified, and acted upon. Dooge (2003) also defines water catchments as typically open systems (complex environmental systems with some degree of organisation) of fluxes of water (both input and output) and other quantities. In Tanzania, a water catchment is defined as an area of land, separated by ridges and hills, which drain all the streams and rainwater to a common outlet such as the outflow of a reservoir, mouth of a bay, or any point along a stream channel (Schösler & Riddington, 2006). In the country, the phrase “water catchment” is sometimes used interchangeably with drainage basin or watershed (Kulindwa et al., 2006). From these definitions, it is clear that a water catchment is an area of land that drains down the slopes until it reaches a common outlet. It is also clear that it can be distinguished from other water features on land surface by the outflow point; all of the land that captures rainwater and drains slowly to one outflow point is a water catchment. Larger water catchments contain many smaller water catchments all draining to one point, which normally are the lower points of the area. These lower points are bodies of water such as rivers, lakes, and the ocean. The easiest way to picture it is to consider it as a giant funnel that catches and directs all of the water that falls into it towards the lowest point of the area. It is also clear that the term “water catchment” is synonymous with other terms such as “drainage basin” and “watershed area”. Therefore, a simpler way of defining and distinguishing it from other surface water features is by saying that is an area of land where all of the water that falls in it ends up in the lower point outlet. All precipitation that falls within a water catchment and not used by existing vegetation, will ultimately seek the lowest points (rivers, lakes and ocean).
Uluguru water catchment: geographical, physical and climatic characterisation
Geographical location
Uluguru water catchments are found in Uluguru Mountain blocks, which are part of thirteen (13) isolated ancient crystalline mountains (also known as the Eastern Arc Mountains) running from the Taita Hills in Southeast Kenya to the Udzungwa Mountains in Tanzania (URT, 2010; Lovett et al., 1995). The Uluguru mountains are situated 07°00′ south and 37°40′ east of the main Eastern Arc Range, as depicted in Figure 2.1 below (Fjeldså et al, 1995). In Tanzania, the mountains are situated 180 km from the coast of the Indian Ocean, and are isolated from the Udzungwa and Robeho mountains by 70 km of low plains, which include the Mikumi National Park (Burgess et al., 2002; Munishi, 1998; Lovett, 1996).
Physical characteristics
As noted in section 2.3.1, the catchment is situated in the mountains series that form a 45.5 km-long chain characterised by very rugged topography, with the tops having steep slopes above 70° (Lovett et al., 1995). The mountains rise steeply from Mgeta and Mvuha floodplains which are 150 m above sea level to a peak of 2 638 m above sea level (Mbilinyi & Kashaigili, 2005). Although the mountains form a continuous ridge or chain, they are physically divided by the gap or depression called “Bunduki” into the Northern Uluguru which is 20.5 km long and 8 km wide, running towards the north- south direction and the Southern Uluguru which is 25 km long and 15.5 km wide, as depicted in Figure 2.2 below (van Donge, 1992). To the south of the mountain chain lies the Lukwangule Plateau and Kimhandu hill which rise abruptly from the lowland plains to 2638 and 2634 m above sea level, respectively (URT, 2010; Lovett et al., 1993). In the north there are Mnyanza (2140 m asl), Magari (2340 m asl), Nziwane (2270 m asl) and Lupanga (2138 m asl) (Doggart et al., 2004). On the east, the mountains drop steeply to 500 m above sea level, and there is then a band of gentle hills about 10–26 km wide (Griffiths, 1993).To the south-east there is a sudden drop in altitude towards the Mbakana River, beyond which there is an extensive complex of low hills dropping towards the Great Ruaha and Rufiji flood plains (Lyamuya et al., 1994). To the north of the range, the mountains drop from 2 000 m to 580 m above sea level within 4 km (Burgess & Clarke, 2000). A lowland plain extends beyond this precipitous; it drops and rises again to 1 260 m above sea level at Mindu Mountain. The foothills are between 200 to 500 m above sea level, with peaks at Mkungwe and Luhakwe which rise up to 1 100 and 900 m above sea level, respectively (Lovett et al., 1995). The foothills divide the main mountain range from the lowland plains that reach the Selou game reserve, Mikumi National Park and the coast (Lovett, 1998). The main lowland includes Kimboza, Ruvu forests and flood plains, and Mgeta flood plains (Pócs, 1976).
Climatic characteristics
The water catchments are under the direct climatic influence of the Indian Ocean from where winds loaded with moisture arrive at the eastern slopes. Apart from winds from the ocean, temperatures also change with altitude. Temperatures range from 26 °C in the lowlands to below zero at the higher altitudes of the mountain chain (Yanda & Munishi, 2007). On average, the tops of the mountains are characterised by cold temperatures between 15 to 18 °C. The temperatures also change over the year, for example at Morogoro, the town just at the northern foothill, the average temperatures are 21.1 °C and 26.5 °C during the coolest months (June and July) and warmest months (October, November and December), respectively (Hall et al., 2009).
The water catchments are also characterised by three main seasons; a long rain season between January and May, with high rainfall between April and May, a dry period from June to September, and a short rain season between October and December (Burgess et al., 2002; Lyamuya et al., 1994). The length of the rain season depends greatly on location and height of the area. For example, the eastern side slopes which are windward receive rainfall between 2000 and 4000 mm per year, which decreases towards the western side of the mountains chain (Mayers et al., 2000). The western area receives rainfall between 890 and 2392 mm per year (URT, 2010). The foothills and lowland receives low rainfall, between 600 and 1 000 mm, compared with the high altitudes (Mittermeier et al., 1998; Lovett et al., 1995).
Dedication
Declaration
Acknowledgements
Abstract
Table of Contents
List of Tables
List of Figures
List of Appendixes
List of Acronyms and Abbreviations
CHAPTER 1: INTRODUCTION
1.1. Background to the problem
1.2. The uluguru water catchment: are there land use externalities to be internalized?
1.3. Objectives of the study
1.4. Hypotheses
1.5. Contribution of the study
1.6. Approaches of the study
1.7. Organisation of the thesis
CHAPTER 2: AN OVERVIEW OF THE ULUGURU WATER CATCHMENTS
2.1. Introduction
2.2. Definition of water catchment
2.3. Uluguru water catchment: geographical, physical and climatic characterisation
2.3.1. Geographical location
2.3.3. Climatic characteristics
2.4. Uluguru water catchment: agro-ecological zones and vegetation distribution
2.4.1. Low altitude dry forest or savannah woodland
2.4.2. Lowland semi-evergreen rain forest zone (the limestone karst areas)
2.4.3. Sub-montane dry forest
2.4.4. Sub-montane evergreen and semi-evergreen forest zone
2.4.5. Montane evergreen forest zone
2.4.6. Upper-montane or upper forest edge
2.5. Importance of Uluguru water catchments
2.5.1. Ecological importance
2.5.2. Hydrological importance
2.5.3. Agricultural importance
2.6. The major threats to Uluguru water catchments
2.6.1. The status of Uluguru water catchments
2.6.2. Impacts of Uluguru water catchment deterioration to downstream
2.6.3. Efforts to combat the deterioration of Uluguru water catchment
2.7. Concluding summary
CHAPTER 3: REVIEW OF THE CONCEPTs OF ECOSYSTEMS, WATER CATCHMENT, ECONOMICALlY VIABLE MANAGEMENT PRACTICES AND THEIR LINKAGE WITH HUMAN WELL-BEING
3.1. Introduction
3.2. The concept of ecosystems and ecosystem services
3.2.1. Definition and composition of ecosystems
3.2.2. Characterising ecosystems
3.2.3. The ecosystem services: definition
3.2.4. Classification of Ecosystem Services
3.3. Ecosystems and human well-being
3.4. Why is an ecosystem a topic of concern?
3.5. Water catchments as ecosystems services providers and human well-being
3.5.1. Water catchment vegetation condition and ecosystem services provisioning
3.6. Water catchments best management practices: the concept and application
3.6.1. The concept of water catchment best management practices
3.6.2. Fruit tree forests
3.6.3. Application of fruit trees as water catchment externalities internalisation land use practice
3.7. Concluding summary
CHAPTER 4: REVIEW OF LITERATURE ON ECOLOGICAL ECONOMIC MODELLING
4.1. Introduction
4.2. An overview of integrating ecology and economics
4.2.1. Motivations of integrating ecology and economics
4.3. The concept of integrated ecological-economic modelling
4.3.1. The system dynamic theory
4.3.1.1. Definition of system
4.3.1.2. Structure and dynamism of ecosystems
4.3.2. How the system runs itself: the feedback loops
4.3.2.1. Types of feedback loops
4.4. Application of integrated ecological economic modelling
4.4.1. In fresh water and marine fishery resources management
4.4.2. In forests, woodlands and landscape management
4.4.3. In wetland management
4.4.4. In water catchments
4.5. Concluding summary
CHAPTER 5: THE CONCEPTUAL FRAMEWORK AND THE EMPIRICAL ECOLOGICAL ECONOMIC MODEL
5.1. Introduction
5.2. The conceptual framework
5.3. The empirical model
5.3.1. Hydrological module
5.3.1.1. Calculation of natural vegetation density (biomass)
5.3.1.2. Estimation of fruit tree density
5.3.1.3. Estimation of crop plant density (tones/ha)
5.3.2. Land use module
5.3.3. Crop production module
5.3.4. Fruit production module
5.3.5. Economic module
5.3.5.1. The net revenue from fruit and crop production
5.3.5.2. Social welfare sub-module
5.3.6. Labour market equilibrium
5.3.7. Catchment commodities market equilibrium
5.3.8. Type of data and sources
5.4. Concluding summary
CHAPTER 6: MODEL PARAMTER ESTIMATION
6.1. Introduction
6.2. Determinants of household land, labour, crops and fruits supply and demand
6.2.1. The analytical framework
6.3. The reduced household model specification
6.4. Data collection for the reduced household model estimation
6.4.1 Reduced household model variables and expected direction of relationships
6.5. Reduced household model econometric estimation procedures
6.6. Other paramters estimation
6.7. Model results and discussion
6.7.1. Summary statistics of variables used in the econometric analysis
6.7.2. Empirical econometric estimation results
6.7.3. Emperical econometric results for other parameters estimated econometrically
6.7.4. Adopted parameters
6.8. Concluding summary
CHAPTER 7: RESULTS FROM ANALYSIS OF THE IMPACTS OF FRUIT TREES ON HYDROLOGICAL, ECOLOGICAL aND ECONOMIC BENEFITS FLOW
7.1. Introduction
7.2. Model testing and validation results
7.3. Development of simulation scenarios
7.4. Simulation results and discussion
7.5. Concluding summary
CHAPTER 8: SUMMARY, CONCLUSIONS and POLICY IMPLICATIONS OF THE RESULTS, AND AREAS FOR FURTHER RESEARCH
8.1. Introduction
8.2. Summary of the key findings and policy implications
8.3. Limitations of the study and areas for further research
References
