**1. Introduction**

A river basin is any area of land where precipitation collects and drains off into a particular point along a channel network or depression [1]. The basin is the basic unit for a hydrological study, probably because the input and output can be quantified and accessed; the basic input is precipitation, and largely rainfall in the humid region while the output or response is the runoff. Rainfall-runoff relationship provides insights into a basin's input-output relationship, and consequently, a basin's behaviour and an indicator of the basin's status of health [2]. Being an open system, a river basin receives inputs (of wastes, seepages, debris, etc.) from anthropogenic and natural activities within the confinement of the basin that are capable of influencing the quality of the river. Also, landcover, topography, the shape and size of a basin are capable of posing significant influence on the basin response to rainfall input [3, 4].

Researchers and policy makers across countries have demonstrated interests in the study of river basins, catchment or watershed, mainly because of the

importance of river basins to human's livelihoods. River basins are wetlands, and home for ecological resources. Adequate management of river basins are known to promote soil and water conservation, and control of soil erosion and resources management. River basins are also main source of freshwater for ecosystem's survival; humans, animals and plants within the drainage basin system often depend on the survival of river basins. Sivapalan [5] described the river basin 'as a fundamental landscape unit for the cycling of water, sediment and dissolved geochemical and biogeochemical constituents, which integrates all aspects of the hydrological cycle within a defined area that can be studied, quantified and acted upon'. Jackson et al. [6] argued that temporal and spatial assessment of land use change in a river basin is important for flood risk management in the area. In the Taw river basin in the southwest England, Williams and Newman [7] demonstrated how the knowledge of the chemistry of streams in the basin can be useful to set criteria for vulnerability zones, control pollution of streams and improve the understanding of biogeochemical cycles in the basin. Evaluation of studies across decades reveals different levels of concerns of methodologies for evaluation of the morphology and biogeochemical cycle in the river basins for the purpose of pollution control, water management and seeking understanding of the effects of landuse changes in hydrological basins.

Despite the importance of the drainage basins, studies have shown that that they are difficult to conceptualise [8], causing a global dedication to 'Prediction in Ungauged Basins (PUB) science programme (2003–2012), that urged a rethink about the different ways in which the form and function of river basin systems are conceptualized [5]. Many river basins in the sub-Saharan Africa are ungauged, probably because of poor access to appropriate technology. There is also poor information about their characteristics and changes that have taken place within them over the years. Except for the few large basins such as Niger that are gauged by international organisations, drainage basins have been poorly studied and understood. The main objective of this chapter, therefore, is to provide an expository review of drainage basin morphometry and the relevance of remote sensing technology, especially for locations in developing countries, where sophisticated remote sensing technology are either expensive or challenged by limited professionals.

## **2. Remote sensing and allied technologies for river basin investigation**

Remote sensing is concerned with acquiring information about the earth's land and water surfaces with reflected or emitted electromagnetic energy. Sensors fixed to a platform detect and record electromagnetic energy from target areas in the field of view of the sensors' instrument. Remote sensing is one of the many methods (others are land and social surveys, extensive field and laboratory analysis, among others) of data acquisition for geographical information system—a computerised system of software, hardware and people (expertise and users) involving data acquisition, storage, manipulation, analysis, retrieval and information presentation aimed at solving a location-referenced problem. Areas of remote sensing application include agriculture, disaster monitoring and mitigation, surveying and urban planning and water resource management. Remote sensing image and geographical information are useful for land use-land cover classification, land degradation and soil erosion [9].

A review of studies on river basin management have shown that whereas earlier focus has been within the perspectives of engineering, extensive social and fieldwork activities, more recent studies have involved the application of remote sensing and geographical information system to link the numerous hydrological

**53**

*Remote Sensing and River Basin Management: An Expository Review with Special Reference…*

parameters, their relationships and other indicators within combined socio-physical and biographical context. Grohmann [10] also argued that recent advancement in computational power of remote sensing and geographic information system has accounted for development in hydrological models and computational (rather than descriptive) interests in morphometry analysis. Application of remote sensing and geographical information systems is often preferred for potential and capacity for customised production of outputs (in terms of resolution and data integration). Sarmah et al. [9], Rai et al. [11], Fenta et al. [12], among other studies argued that hydrological model inputs have successfully been derived from remotely sensed data and geographical information-based modelling activities. In all, remote sensing and geographical information system's applications to river basin often assume

Bertalanffy [13] described the system as an interdisciplinary study of systems; for elucidation of the system's dynamics, constraints, conditions and principles. In the river basin, the purpose of a system theory is to achieve optimized equifinality in the explanation of functions and processes within a unit the hydrological system [14]. The systems approach provides a useful conceptual vehicle for the study of the drainage basin. Studies based on a system theory measure the inputs, outputs, transfers and transformations that characterize this system. The system analysis also serves useful purpose in organizing process studies into a framework that allows both qualitative and quantitative data-base modelling and prediction [15, 16]. A hydrological system will comprise a set of drivers of hydrological processes and

Until recently when remote sensing and GIS are integrated in hydrological models, existing typical hydrological models are either parametric, physically based or deterministic. Parametric models describe the component hydrological processes, and are made up of interconnected reservoirs representing the physical elements of a catchment; i.e., rainfall, infiltration, percolation, evaporation, runoff and drainage. They often adopt semi empirical equations, and model parameters are assessed from field data and calibration. Many conceptual models have been developed with different levels of complexity, including the Stanford Watershed Model IV (SWM) developed by Crawford and Linsley [17], and Hydrologiska Byrans Vattenavdelning (HBV) model [18]. In addition, physically based or mechanistic models provide mathematical representation of reality through the principles of physical processes. They use of variables that are measurable functions in both space and time. They can overcome the limitations of empirical and conceptual models because of the use of parameters that have physical interpretation [19]. Example includes the Systeme Hydrologique European (SHE/MIKE SHE) model in 1990, the Soil and Water Assessment Tool (SWAT) Model as well as Topmodel [20]. Beven et al.'s [20] topographical (TOP) model is a rainfall-runoff model that makes use of topographic information related to runoff generation for prediction in single and multiple basins. Other models were the empirical, metric models or data driven models that involve the use of information from the existing data without considering the features and processes of the hydrological system. The model involves mathematical equations derived from concurrent input and output time series but not from the

In river basins, parameterisation can be a major modelling challenge because they (parameters) are many. Common morphologic parameters in drainage basin stream order, number, length ratio, bifurcation ratio, drainage density, stream or

*DOI: http://dx.doi.org/10.5772/intechopen.88681*

that the drainage basin is a system—that it actually is.

their relationships with components of hydrological systems.

physical processes within and over the catchment.

**3. Drainage basin as a system**

*Remote Sensing and River Basin Management: An Expository Review with Special Reference… DOI: http://dx.doi.org/10.5772/intechopen.88681*

parameters, their relationships and other indicators within combined socio-physical and biographical context. Grohmann [10] also argued that recent advancement in computational power of remote sensing and geographic information system has accounted for development in hydrological models and computational (rather than descriptive) interests in morphometry analysis. Application of remote sensing and geographical information systems is often preferred for potential and capacity for customised production of outputs (in terms of resolution and data integration). Sarmah et al. [9], Rai et al. [11], Fenta et al. [12], among other studies argued that hydrological model inputs have successfully been derived from remotely sensed data and geographical information-based modelling activities. In all, remote sensing and geographical information system's applications to river basin often assume that the drainage basin is a system—that it actually is.

## **3. Drainage basin as a system**

*Current Practice in Fluvial Geomorphology - Dynamics and Diversity*

importance of river basins to human's livelihoods. River basins are wetlands, and home for ecological resources. Adequate management of river basins are known to promote soil and water conservation, and control of soil erosion and resources management. River basins are also main source of freshwater for ecosystem's survival; humans, animals and plants within the drainage basin system often depend on the survival of river basins. Sivapalan [5] described the river basin 'as a fundamental landscape unit for the cycling of water, sediment and dissolved geochemical and biogeochemical constituents, which integrates all aspects of the hydrological cycle within a defined area that can be studied, quantified and acted upon'. Jackson et al. [6] argued that temporal and spatial assessment of land use change in a river basin is important for flood risk management in the area. In the Taw river basin in the southwest England, Williams and Newman [7] demonstrated how the knowledge of the chemistry of streams in the basin can be useful to set criteria for vulnerability zones, control pollution of streams and improve the understanding of biogeochemical cycles in the basin. Evaluation of studies across decades reveals different levels of concerns of methodologies for evaluation of the morphology and biogeochemical cycle in the river basins for the purpose of pollution control, water management and seeking understanding of the effects of landuse changes in

Despite the importance of the drainage basins, studies have shown that that they are difficult to conceptualise [8], causing a global dedication to 'Prediction in Ungauged Basins (PUB) science programme (2003–2012), that urged a rethink about the different ways in which the form and function of river basin systems are conceptualized [5]. Many river basins in the sub-Saharan Africa are ungauged, probably because of poor access to appropriate technology. There is also poor information about their characteristics and changes that have taken place within them over the years. Except for the few large basins such as Niger that are gauged by international organisations, drainage basins have been poorly studied and understood. The main objective of this chapter, therefore, is to provide an expository review of drainage basin morphometry and the relevance of remote sensing technology, especially for locations in developing countries, where sophisticated remote sensing technology are either expensive or challenged by limited professionals.

**2. Remote sensing and allied technologies for river basin investigation**

A review of studies on river basin management have shown that whereas earlier focus has been within the perspectives of engineering, extensive social and fieldwork activities, more recent studies have involved the application of remote sensing and geographical information system to link the numerous hydrological

Remote sensing is concerned with acquiring information about the earth's land and water surfaces with reflected or emitted electromagnetic energy. Sensors fixed to a platform detect and record electromagnetic energy from target areas in the field of view of the sensors' instrument. Remote sensing is one of the many methods (others are land and social surveys, extensive field and laboratory analysis, among others) of data acquisition for geographical information system—a computerised system of software, hardware and people (expertise and users) involving data acquisition, storage, manipulation, analysis, retrieval and information presentation aimed at solving a location-referenced problem. Areas of remote sensing application include agriculture, disaster monitoring and mitigation, surveying and urban planning and water resource management. Remote sensing image and geographical information are useful for land use-land cover classification, land degradation and

**52**

soil erosion [9].

hydrological basins.

Bertalanffy [13] described the system as an interdisciplinary study of systems; for elucidation of the system's dynamics, constraints, conditions and principles. In the river basin, the purpose of a system theory is to achieve optimized equifinality in the explanation of functions and processes within a unit the hydrological system [14]. The systems approach provides a useful conceptual vehicle for the study of the drainage basin. Studies based on a system theory measure the inputs, outputs, transfers and transformations that characterize this system. The system analysis also serves useful purpose in organizing process studies into a framework that allows both qualitative and quantitative data-base modelling and prediction [15, 16]. A hydrological system will comprise a set of drivers of hydrological processes and their relationships with components of hydrological systems.

Until recently when remote sensing and GIS are integrated in hydrological models, existing typical hydrological models are either parametric, physically based or deterministic. Parametric models describe the component hydrological processes, and are made up of interconnected reservoirs representing the physical elements of a catchment; i.e., rainfall, infiltration, percolation, evaporation, runoff and drainage. They often adopt semi empirical equations, and model parameters are assessed from field data and calibration. Many conceptual models have been developed with different levels of complexity, including the Stanford Watershed Model IV (SWM) developed by Crawford and Linsley [17], and Hydrologiska Byrans Vattenavdelning (HBV) model [18]. In addition, physically based or mechanistic models provide mathematical representation of reality through the principles of physical processes. They use of variables that are measurable functions in both space and time. They can overcome the limitations of empirical and conceptual models because of the use of parameters that have physical interpretation [19]. Example includes the Systeme Hydrologique European (SHE/MIKE SHE) model in 1990, the Soil and Water Assessment Tool (SWAT) Model as well as Topmodel [20]. Beven et al.'s [20] topographical (TOP) model is a rainfall-runoff model that makes use of topographic information related to runoff generation for prediction in single and multiple basins. Other models were the empirical, metric models or data driven models that involve the use of information from the existing data without considering the features and processes of the hydrological system. The model involves mathematical equations derived from concurrent input and output time series but not from the physical processes within and over the catchment.

In river basins, parameterisation can be a major modelling challenge because they (parameters) are many. Common morphologic parameters in drainage basin stream order, number, length ratio, bifurcation ratio, drainage density, stream or

channel frequency, texture ratio, form factor, circulatory ratio, elongation ratio, relief ratio and length of overland flow. The stream orders and stream number typically provide information on other parameters, suggesting complexity in the parameters [21]. Subsequently, major advancements in remote sensing technology are the availability of many high-quality drainage models or abstraction of reality.

## **4. Development in modelling drainage basins**

The river basin concept aids the development and management of water resources in many countries, and consequently interests planners and engineers, and scientists, including agriculturists that are interested in the elucidation of hydrological processes. Improvements in water supply and demand enhance hydropower generation, flood control, water supply and irrigation; Recreation, aesthetic ammenities, ecosystem services pollution control are also justifications for scientific interests; especially among hydrologists, soil scientists, geologists, physical geographers and environmental modellers [22]. Concerns about basins probably became noticeable since 300 BC [23, 24], with improved focus on hydraulic infrastructure over flood basins and dams for flood disaster control, intensive agriculture, and industrialisation. Parameterisation of basins for explanatory and predictive modelling purposes later became popular with the thoughts of Horton [25] and Langbein [26], emphasising concerns on runoff regeneration mechanisms.

Digital elevation models (DEMs) are frequently explored for the morphometric analysis of river basins through the extraction of topographic parameters and stream networks, and their use presents many advantages over traditional topographical maps. DEM is a regular gridded matrix representation of the continuous variation of relief over space [27], and a digital model of the land surface form. The most important requirement of any DEM is that it should have the required accuracy and resolution and be stripped of data voids [28]. Recent increase in the application of DEMs can be attributed to their easy integration within a GIS environment. The Shuttle Radar Topography Mission (SRTM) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) are samples of advanced global DEMs. They have been adopted in a variety of studies where terrain and drainage factors play prominent roles because of convenience of users and open-access availability of the DEMs. The DEM approach is also useful for characterising stream basin because of its easy integration within the GIS environment. It is fast, precise, updated and it is an inexpensive method for drainage basin analysis [29]. The DEM will help to show the general topography of the area and the direction of flow of the streams.

In addition, studies have shown that the advantage of timeliness and ability to capture information on larger areas than in studies with traditional surveying methods [21, 30–33] are main strengths of remote sensing and GIS in river basin investigations. GIS is also a viable tool for establishing relationship between drainage morphometry and properties of landforms useful in the development and planning of drainage system. Results from remote sensing and GIS are known to provide decision support information for prioritization of basins, water conservation and natural resource management. Specific results of basin morphometry are also advantageous in the recognition of different terrain parameters and basin's health; measured in terms of runoff and sediment yield index from a basin, flow characteristics and fluvial processes [34, 35]. Malik [30] adopted drainage density and stream frequency to explain control of the runoff pattern, sediment yield and other hydrological parameters within the basin. In addition, Kulkarni [35] argued that dynamism of river morphology is the aftermath of natural processes as well

**55**

*Remote Sensing and River Basin Management: An Expository Review with Special Reference…*

as anthropogenic intervention, hence both causes can be explained by the changes observed in the basins. In general, good information about basin morphometry generally assists in making decisions for combating hydraulic structures to combat erosion [36] and to arrive at decisions regarding suitable sites for soil and water conservation structures [37]. In many basins, the remote sensing approach is the only option, especially in difficult or dangerous terrain especially in Congo and Amazon. Most studies from the Nigerian environment have focused mainly on the drainage basin morphometry from the angle of landuse/landcover change [38–40]. Orunonye et al. [39] carried out morphometric studies on River Lamurde in Jalingo, Nigeria, and explained that lack of reliable hydrological data has been a major constrain for use by water resource managers and researchers in Nigeria, therefore, the only alternative was to resort to measures of appraising and evaluating the natural water resources potential of basins without stream gauge records using series of

generalised regional relationships based on morphometric parameters.

Main precipitation input into the drainage basin in Nigeria is rainfall based on its location in the tropical region. Whereas the ground-based data has become rather expensive, despite being coarse (almost only available for locations around airports, which are often not representative of the large area that they are meant to represent), satellite-based data sources are poorly explored. This is probably because of the poor awareness and low capacity for remote sensing analysis among many

Meanwhile, satellite-based precipitation estimation algorithm use information from two primary sources; the visible and infrared channels from geosynchronous satellites. Many meteorological weather satellites have been launched in the last few decades and some of these satellite rainfall products are freely available in real time on the internet via the web or File Transfer Protocol (FTP). Some of the freely available spatially distributed satellite-based rainfall estimates are the Tropical Rainfall Measuring Mission (TRMM), EUMETSAT's Meteorological Product Extraction Facility (MPEF), and Multi-Sensor Precipitation Estimate-Geostationary (MPEG). Others include the Climate Forecast System Reanalysis (CFSR), the NOAA/Climate Prediction Center Morphing Technique (CMORPH), Climate Research Unit (CRU), and Global Precipitation Climatology Centre (GPCC), European Centre for Medium-Range Weather Forecasting (ERA-Interim), the Naval Research Laboratory's blended product (NRLB) and African Regional Climate (ARC) [41]. These satellites have different spatial and temporal resolutions, thus providing a stream of datasets in support of operational meteorology and many other disciplines. They are scaled to match rain-gauge measurements on land points where ground measurements are available. The TRMM, CRU, GPCC, GPCP, and ERA-INTERIM (Medium-Range Weather Forecasting Reanalysis-Interim) were commonly selected and chosen for use in many studies and have been shown to possess complementary capacity with ground based data based on their high spatial and temporal characteristics, free availability and accessibility online and minimal frequency of missing data. The centre for this is the latest global atmospheric reanalysis (third generation reanalysis) which computes synoptic hourly, daily and monthly means of precipitation by accumulating the available hourly forecast for each calendar month [41]. The ECMWF ERA-Interim reanalysis, provides global precipitation at gridded spatial resolution

*DOI: http://dx.doi.org/10.5772/intechopen.88681*

**5. Case study analysis**

**5.1 Precipitation input measures**

climate experts in the country.

*Remote Sensing and River Basin Management: An Expository Review with Special Reference… DOI: http://dx.doi.org/10.5772/intechopen.88681*

as anthropogenic intervention, hence both causes can be explained by the changes observed in the basins. In general, good information about basin morphometry generally assists in making decisions for combating hydraulic structures to combat erosion [36] and to arrive at decisions regarding suitable sites for soil and water conservation structures [37]. In many basins, the remote sensing approach is the only option, especially in difficult or dangerous terrain especially in Congo and Amazon.

Most studies from the Nigerian environment have focused mainly on the drainage basin morphometry from the angle of landuse/landcover change [38–40]. Orunonye et al. [39] carried out morphometric studies on River Lamurde in Jalingo, Nigeria, and explained that lack of reliable hydrological data has been a major constrain for use by water resource managers and researchers in Nigeria, therefore, the only alternative was to resort to measures of appraising and evaluating the natural water resources potential of basins without stream gauge records using series of generalised regional relationships based on morphometric parameters.
