1.1 Introduction
Catchment areas and their proper management have become a major issue of concern for resource managers world-wide. This growing level of concern was prompted by an increase in the number of major catchment areas being deteriorated by flooding and soil erosion (Ganoulis (2003), Gelsomino et. al. (2006), Chang Huang et. al. (2007), Malik and Matyja (2008) and Pignatelli et.
al. (2009)), These and other catchment problems (e.g. water pollution) are not only isolated in solving water management issues but also include engineering, biophysical, economic, social, environmental, political and institutional issues. Resolving these problems requires integration of interdisciplinary organisations for acquiring all necessary resources (e.g. information, hardware, software, expertise, funding). In developing countries, integrated catchment management is further restricted by lack of quality and quantity of appropriate data as well as insufficient capacity in human resources. Such issues create challenges and so it is even more important to develop tools that could be used to define and apply the policies and strategies at least at the regional scale in order to effectively deal with catchment management problems. The main tool in this regard is a catchment hydrological model developed within the framework of a Decision Support System (DSS), i.e. a Geographic Information System (GIS) enabled model environment.
GIS can store, analyse and manipulate spatial data. In this research project GIS was also used to
develop management strategies and more importantly as a DSS for mitigation measures to be taken for flood prevention and control in the area under investigation i.e. River Fani Catchment in North Albania.
Traditionally catchment modelling is used for better understanding of the hydrology of the area under study and consequently for solving catchment problems. It is a complex process and involves representation of the water cycle processes at a scale and/or level appropriate to the catchment problem being addressed. Such methodology was adopted in this research project, by developing a rainfall-runoff model to predict the spatial and temporal response of the River Fani Catchment. Runoff prediction by hydrograph development is a very important part in rainfall-runoff modelling. This is because the hydrographs produced are often required as the basis for an engineering design. The amount of runoff produced by a catchment is dependant upon numerous factors (e.g. the way in which hydrological parameters such as rainfall intensity, Land Cover (LC) and soil type are distributed). Therefore a significantly large number of spatially and temporally distributed data (e.g. terrain models) are required to derive the hydrological parameters required in the modelling procedures. Additional modelling data required include:
catchment area, boundary and shape, stream network, topography, land use/cover (LULC), soil type, drainage density and drainage pattern. The quality of these data and the robustness of the underlying assumptions used indicate how useful a model can be. In view of the data challenges encountered in this research project (see Chapter 3, Section 3.4), the use of satellite Remote Sensing (RS) became particularly important as a data source.
Satellite remote sensing technology has come a long way since the launch of the world’s first satellite, Sputnik, in 1957. In 1972, Landsat MSS, a high spatial resolution satellite was launched and the use of its data that became widely available, enabled significant advances in the field of
earth monitoring. In 1984, spatial, geometrical, and radiometric resolutions were significantly enhanced with the launch of Landsat-4 and its TM sensor. Since then, more satellites were launched with improved sensors for example Landsat 5 that carried the MSS and TM sensors (Appendix A, Plate A1) and Landsat 7 launched in 1999 that carries the ETM+ sensor (Appendix A, Plate A2). Therefore, the Landsat satellites series prime emphasis is on remote sensing of land resources.
Since the launch of Landsat and generally high spatial resolution satellites for monitoring vegetation, the application of remote sensing in hydrology as well as the technique of land use mapping (which forms the backbone of this and many other hydrological projects), has increasingly gained recognition. Consequently, research evolved in the applications of remote sensing for land management and in hydrology, towards developing methods to use satellites of various spatial resolutions in monitoring the environment. For land management, data on reflective, thermal and dielectric properties of the Earth’s surface can be provided using a variety of sensors (Engman and Gurney (1991)). On the other hand, in the case of hydrology, remote sensing techniques measure hydrological variables indirectly and hence, the electromagnetic variables (measured by remote sensing techniques) have to be related to the hydrological variables empirically or with transfer functions. Additionally, in the case of hydrological models which are not structured to receive and analyse remotely sensed data directly, advanced computer hardware and software have to be used for imagery storage, analysis and interpretation (e.g.
ERDAS Imagine, ENVI, IDRISI and PCI Geomatica). In the current research project, ERDAS Imagine software was opted for and used to analyse satellite imageries.
1.2 The River Fani Catchment Case Study - Overview of the Challenges
This research project was initiated and funded by Aid-in-Action (AIA) Porthcawl in collaboration with the University of Glamorgan. AIA Porthcawl is a South Wales charity organisation set up in 1989 which became a registered charity in 1991 with the motivation and ‘goal’: “We aim to challenge inequality, poverty and injustice, through sharing knowledge and skills to empower the disempowered. We will work with people of all faiths, ethnicity, gender orientation, background and ability.” Over the years AIA Porthcawl has helped many countries with difficulties namely, Albania, Belarus, India, Peru, and Zambia. In Albania, AIA’s work is focused on the town of Rubik, situated on River Fani, in North Albania.
Rubik town and generally Mirdita region in the northern part of Albania endure environmental problems such as pollution and deforestation (Samimi et al. (1997) and Qiriazi and Sala (2000)).
These problems were mainly due to the lack of environmental protection strategies and resulted in social, health, environmental, and financial consequences for the populations of the area.
According to Samimi et al. (1997), the following took place; (a) the uncontrolled mine activities in the surrounding mountains caused pollution, (b) illegal logging resulted in deforestation and (c) hunting activities damaged fauna. Consequently, the discharge of the River Fani increased (the average annual discharge is 103 m3/s, which is considered high for the catchment), causing major frequent flooding problems to Rubik town. In addition, these problems have lead to river bank instabilities, landslides and erosion on a regular basis, deterioration of agricultural land and changes in the morphology of the river reaches towards the town. Thus, these let to impacting heavily on the quality of life of the locals, endangering their lives, threatening property as well as affecting the environmental sustainability of the Catchment. As a result, the residents of Rubik town abandon their houses and relocate to safer areas on a regular basis.
In aid of this situation, AIA Porthcawl attempted to provide localised solutions, such as bank stabilisation with different methods but these were unsuccessful in abating the problems. AIA Porthcawl then approached the University of Glamorgan and after extended discussions it was agreed that a sustainable solution to the localised problems in Rubik was to carry out a catchment wide study of the area in order to better understanding its hydrological behaviour. This should help in the provision of localised solutions.
The solutions/measures that can be considered and implemented in catchment management can be distinguished in (a) structural and (b) non-structural (e.g. flood forecasting and warning systems, and flood risk maps). For both measures, a better understanding of the causes of floods, erosion and instability in the region, needs to be established, which requires the use of hydrological models at the scale of the river basin. Developing such a model could contribute not only in the provision of localised solutions that are required but also could significantly aid to the environmental management of the whole catchment.
1.3 Research Aims and Objectives
The general aims of the thesis were: (a) to develop and apply a physically based hydrological model of the River Fani Catchment (in the northern region of Albania) with an emphasis on the use of GIS and RS and, (b) to prepare a flood risk assessment study for the River Fani Catchment.
The work in this thesis aimed also to merge both new and old techniques and demonstrate how technical advances may aid the hydrologist in the modelling of variable events such as rainfall and runoff.
The research investigation was focused on the application of both RS and GIS technologies to overcome data limitations of the mountainous remote Catchment and the application of different hydrological and hydraulic modelling environments and tools (e.g. WMS, HEC-RAS) for
modelling different rainfall-runoff scenarios. Even though much work has been done on the application of GIS and RS in hydrological modelling, there are still many unresolved aspects that have to be addressed and therefore, there is a need for further work. For example, better understanding of spatial hydrology is required, especially in remote, mountainous and ungauged catchments with limited available conventional data.
The specific objectives of the thesis were:
1. Monitor and map various hydrologically significant changes (e.g. deforestation) in the River Fani Catchment, with the processing and analysis of remote sensing imagery (Landsat, Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER)).
2. Develop a hydrologic model using multi-source and multi-scale data (land cover CORINE data, satellite images, field archived data and maps) in a GIS-integrated hydrological modelling package (WMS, HEC-RAS).
3. Quantify channel flow for various specified precipitation events and for various scenarios of change or developments in the Catchment area.
4. Develop a decision support management system with the use of GIS and RS of a remote mountainous catchment that makes recommendations on various conservation measures based on a ‘What-if’ analysis and simulation results of the hydrologic model, to be carried out later in this work.
The output of this research was anticipated to contribute towards the following:
Improved quality of life for the residents of the Rubik area of Albania through better catchment management measures that are proposed.
Extension of results and applications to other parts of Albania (since hydrological problems in the Mirdita region are common to other parts of the country).
Application of multi-source/multi-scale data (particularly from remote sensing) to enhance the understanding of catchment runoff dynamics in a mountainous area with limited archived field data.
Mapping of hydrologically significant change in the River Fani Catchment to show its effect on hydrological processes and their interactions within the area.
1.4 Structure of the Thesis
Following this introductory chapter, Chapter 2 is review of literature, looking at hydrological modelling; their different processes and relationships as well as the classification systems into which are aggregated. The limitations, advantages and disadvantages of several hydrological models are also examined and are on these that the selection criteria for an appropriate hydrological model for this research project are based. Once an appropriate model is selected, the review is concentrated on the data scarcity/limitations of remote catchments and goes into investigating advances in technology such as the GIS and RS in tackling them.
In Chapter 3, the River Fani Catchment topography, climate, hydrology, geology and land use are described. Catchment degradation, erosion, landslips and flooding are also covered in this Chapter giving an overview of the situation and the problems encountered in the area. Acquiring such data for this research project embraced challenges. In overcoming the challenges the use of GIS and RS is introduced and described in this Chapter.
Chapter 4 starts with a description of the remote sensing data acquired for the Catchment from different sensors (such as the Landsat TM, ETM+, MODIS and ASTER), followed by the pre-processing techniques used to correct and enhance the images. The analysis of the images using
image processing systems and GIS aided the derivation of parameters, land cover and change detection maps to be used in the hydrological model. This Chapter also examines the changes that occurred in the Catchment from 1984 to 2000 and the soil erosion potential of the area.
Chapter 5 – This Chapter describes the development of the hydrologic model from the data derived in Chapter 4. It starts with the modelling technique used, followed by the use of the WMS tools to construct the hydrologic model of the Catchment, using the derived GIS layers (e.g. land cover, soil, Digital Elevation Model (DEM)). The calibration and validation of the model is presented based on hydrologically similar catchments and different rainfall-runoff scenarios are examined. In order to investigate the effects of these scenarios on the Rubik town (situated on the banks of River Fani Catchment) a hydraulic model was constructed using HEC-RAS. The results and analysis of the hydraulic model as well as the floodplain delineation are described in this Chapter.
One of the objectives of this research project is to make recommendations on various conservation measures based on a ‘What-if’ analysis and simulation results of the hydrologic model. Chapter 6 presents the different ‘What-if’ scenarios for both the hydrologic and the hydraulic models, analyses their results and makes catchment conservation and management proposals.
Finally, in Chapter 7 the conclusions of the research are summarised and recommendations made for areas of further research. To preserve the continuity of the main chapters some detailed information has been placed in the appendices at the end of this thesis.