Resources are essential elements for the sustainability of human beings. Among all the resources, water and land are among the most important resources. Hydrogeomorphology deals with both of these resources. Hydrogeomorphology is a new field in geosciences that has emerged to study the linkages between water processes and landforms.
It is a combination of three different terms:
Hydro: refers to water, including both surface and underground water
Geo: refers to the ground and the landforms
Morphology: refers to the surface characteristics of the landforms
Hydrogeomorphology studies two major aspects:
- Effects of moving water to hill slopes, rivers and landscapes on geomorphic processes and geomorphic forms
- Effects of geomorphic form on the spatial and temporal distribution of shallow groundwater
So hydrogeomorphology is an interdisciplinary science that studies the link between two important branches of geosciences i.e. hydrology and geomorphology. Other than hydrology and geomorphology, the concepts of hydrogeomorphology are also largely derived from the different branches of geosciences like geology, remote sensing, climatology and natural hazards.
To study hydrogeomorphology, it is important to understand the difference between the three branches of geosciences i.e. hydrogeomorphology, geology, hydrology, and Geomorphology.
Hydrogeomorphology, geology, hydrology and geomorphology are different branches of geosciences that cover different subject matter but often get confused. Geology is a branch of geosciences that studies earth materials along with the processes working on them.
Hydrology studies the occurrence, distribution, movement and relationship of water with all aspects of its environment. Geomorphology is the subfield of geology that studies the structure and evolution of the earth’s surface. It deals with the origin and changing structure of the earth’s landforms.
History of Hydrogeomorphology
In 1973 Scheidegger used the term ‘hydrogeomorphology’ for the first time in a science article in the Journal of Hydrology. He defined hydrogeomorphology as the study of shapes caused by water activity. He considered water as the most important shaping agent of the landforms.
In 1988, Richards used this term again after a gap of 15 years to emphasise the role of hydrogeomorphological studies in understanding the prediction scenarios for river evolution at the hydrographic basin scale.
Okunishi also did research on the term “hydrogeomorphology” in the year 1994, which further strengthened the growth of hydrogeomorphology as an important branch of geosciences. He defined hydrogeomorphology as the study of the interactions between hydrological and geomorphological processes.
In recent years researchers of hydrogeomorphology are emphasising more on explaining the landforms i.e. their functions and the process through which the landforms have evolved along with the hydrological conditions. In 2010 Malavoi and Bravard stated the use of hydrogeomorphology in France for demarcating flooded areas based on topographic and geomorphic characteristics of the bottom valley.
In 2012 Santos et al. defined hydrogeomorphology as a science that tries to understand how the hydrological processes contribute to the moulding and the evolution of the landscape and how the landforms influence or control the hydrological processes at different temporal and spatial scales.
The surface and groundwater influence the formation, development and characteristics of the landforms, and in its turn, the landforms affect the intensity, magnitude and duration of the hydrological process.
Santos et al. (2012) have given three models to establish the link between hydrology and geomorphology under hydrogeomorphology. These models are:
- The first model suggests a superposition of the hydrology and geomorphology common areas to avoid any interface between them. This means that both the sciences, i.e. hydrology and geomorphology, will use similar methods, but there will be no interaction between them.
- The second model suggests the crossing between hydrology and geomorphology, which thus becomes the common object for both sciences. This model was based on the statement given by Okunishi (1994) that hydrogeomorphology is “a little hydrology and a little geomorphology.”
- The third model considers hydrogeomorphology as an independent branch of science which incorporates both its characteristics and elements from hydrology and geomorphology.
Fundamentals of Hydrogeomorphology
The important fundamentals of hydro-geomorphological studies are given below:
Mechanism and Process: Mechanism describes the physical and chemical effects, while the process is the simultaneous operation of a set of specific mechanisms over a specific period. In hydro-geomorphological studies, the landforms are studied concerning the groundwater conditions of the area.
So while studying the mechanism and process in Hydrogeomorphology, the morphological, climatic and hydrological criteria are considered. The study of the mechanism and the process involved helps to explain the morphology and distribution of landforms.
Basic Tools Required: To conduct a hydro-geomorphology study, it is very important to first design a geographic database including both spatial and non-spatial data requirements with their sources. The most important requirement for studies in hydrogeomorphology is mapping.
This includes topographical maps, geological maps of the area, soil maps, rainfall and climate distribution maps, geomorphological maps, population density maps and groundwater fluctuation maps. In India, the sources for these maps are various government agencies and publications like:
- Survey of India for Toposheet Maps
- National Bureau of Census for Population Density Map
- Geological Survey of India for Geological Maps
- Indian Meteorological Division for Climate and Rainfall Distribution Data Maps
- National Bureau of Soil Survey and Landuse Planning, for Soil Maps
- All India Soil and Land Use Bureau for Landuse and Land Cover Maps
Along with the maps, it is also important to update the data through satellite data collected from various national and international remote sensing agencies like the Indian Institute of Remote Sensing Agency (IIRS), Dehradoon, National Remote Sensing Agency (NRSA), Hyderabad.
Properties of Earth Materials: Hydrogeomorpholgists study the properties of earth materials to get a better understanding of the mechanism and process behind the geomorphic features. The emphasis is on the properties of the parent material influencing the formation and development of landforms along with the hydrological conditions. Type of rock, weathered material, soil, superficial deposits, shear strength, porosity and mineral composition are some of the important properties that hydrogeomorphologists study during their research.
Spatial Scales of Hydrology: Hydrogeomorphology not only studies the effect of hydrological processes on geological processes but also analyses the effect of landforms on the hydrology of an area. Thus the study of scaling effects becomes essential. The spatial scales in hydrology can be distinguished into three types:
- Local Scale: On a local scale, the parameters like slope angle directly influence the water flow path geometries, flow velocity and quantity.
- Hill Slope Scale: In hills, the slope scale is characterised by its runoff production. The soil properties influence the runoff production in the hill slope scale.
- Catchment Scale: In the catchment scale, the morphometry of the basin influences the runoff production.
Dimensions of Hydrological Units: Hydrogeomorphology studies the role of dimensions of hydrological units in defining the size and dimensions of geological landforms. In India, Watersheds are delineated at various levels based on the drainage network.
A Watershed can be defined as an area of land that includes a common set of streams and rivers draining their water into a single larger water body. Water in watersheds can come from any of the sources of water from precipitation, in the form of rain or snow or as groundwater or surface runoff. The size of the watershed depends on the size of the stream or river, the point of interception of the stream or river, the drainage density and its distribution.
Hydrological Cycle and Water Budget
Hydrology is an important part of hydrogeomorphology it becomes important for hydro-geomorphologist to study the hydrological cycle, water balance and water budget for their research studies. Water circulation into different forms between various spheres of the earth’s surface is called the hydrological cycle. The hydrological cycle recycles the earth’s water.
The hydrological cycle includes the inflow, outflow and storage of water at different levels. The inflows add the water into the system while outflow subtracts the water. Storage helps in the retention of water in the system.
Water budget studies the water availability. It includes the balance between the inflows and outflows of the water. In the water or hydrologic budget, the inputs are derived from precipitation, surface water inflow and groundwater inflow. Output factors include evaporation, combined surface and groundwater outflow and transpiration.
Application of Remote Sensing and Geographic Information Systems in Hydrogeomorphology
To properly understand hydrogeomorphology, it is essential to collect geological, structural and hydrological data on the region. Hydrological data collection, i.e. assessing surface and sub-surface water resource data, requires a lot of time and manpower.
GIS and remote sensing are the platforms through which all the required data can be collected with better accuracy and time. Remote Sensing and GIS carry great importance in hydro geomorphological studies.
Before looking at the application of remote sensing and Geographic Information Systems (GIS) in hydrogeomorphology, it is important to understand the concept of remote sensing and GIS.
In the early 1960s, the term remote sensing was first used for the first time. Remote sensing can be defined as the process of acquiring information through recording devices called sensors about objects and phenomena without getting in physical contact with them. In remote sensing, data acquisition is done through different stages.
The stages involved in remote sensing for data collection are given below:
- Source of energy
- Transmission of energy from the source to the earth’s surface
- Interaction of energy with earth’s surface features
- Propagation of reflected energy/emitted energy through the atmosphere
- Detection of reflected /emitted energy by the sensor
- Conversion of energy recorded into digital /photographic form
- Extraction of the information from the data generated
- Conversion of information into map/tabular form
Satellite imageries and aerial photographs are the outputs of the process of remote sensing passing all the above-mentioned stages. The satellite images and aerial photographs generated by remote sensing are interpreted through the different elements of visual interpretations. The important elements are tone, texture, size, shape, shadow, pattern and association.
In the study of hydrogeomorphology, the same elements of visual interpretation are used to get the information through the interpretation of the images generated by remote sensing of the landforms and the regions covering the water resources.
The Geographic Information System (GIS) is a tool for digitally capturing, managing, analyzing and displaying geographic data using computer hardware and software. Maps, computer hardware and software, information, procedures and people are the important components of GIS.
GIS is an important tool for geographic studies because it analysis and answers real-world problems. It makes dynamic maps and displays detailed information about the features in the maps. It not only displays but also studies and establishes a relationship between the features.
The application of GIS can be seen in studying the relationships, patterns and trends of various spatial and non-spatial elements of the earth’s surface. GIS contributes vastly to the study of Land use/land cover studies along with the studies associated with water and soil resources.
Over the years, rapid increases in population, rapid urbanisation and industrialisation, along with failure in monsoons, have restricted surface water availability. The limited availability of surface water has increased the burden on groundwater resources. This has resulted in higher rates of groundwater withdrawal which further results in groundwater depletion at alarming rates.
For management and conservation, the study of groundwater resources is very important. Satellite remote sensing has made it easy to study the spatial distribution of groundwater prospects based on geomorphology and other associated features.
Satellite remote sensing is also a useful technique for groundwater exploration along with delineating the hydrogeomorphological units. Groundwater accumulation, infiltration and movement largely depend on the factors like drainage, geomorphology, the slope of the terrain, vegetation, soil and depth of weathering. All these factors can be easily studied using remote sensing at various levels.
Remote sensing not only studies the hydrological aspects but is also an effective tool for geological, structural, and geomorphologic analysis and their mapping due to its synoptic, multi-spectral and multi-temporal capabilities. Geologists largely depend on satellite imagery to collect data on various lithological units.
The important advantages of remote sensing in hydro geomorphological studies are as follows:
- Remote sensing has access to large areas and even inaccessible areas.
- The aerial photographs and satellite imageries provide detailed information about the uppermost layer of the earth’s surface, which is essential for hydro geomorphological studies.
- Digital enhancement of satellite imageries improves the level of information useful in the study of hydrogeomorphology.
- Data generated by remote sensing provide more accurate and spatial information in comparison to hydrogeological surveys.
- Through remote sensing, hydro geomorphological terrain mapping and analysis of their processes can be done easily.
- This will further help in soil resource mapping, groundwater potential zone demarcation, landscape ecological planning, hazard mapping and their environmental applications.
- The application of geomorphologic mapping using remote sensing can also be seen in land use planning and water resource management.
The IRS-1C and 1D data of WiFS, LISS-III and PAN sensors are highly useful for geological mapping. The WiFS camera gives the synoptic coverage of large areas and thus is useful for regional scale mapping and understanding. The finer geological features, like the traces of bedding and minor joints, can be easily identified through panchromatic data. The panchromatic data provides detailed mapping, while the multispectral LISS-III gives semi-detailed mapping.
Along with remote sensing, in recent years, several techniques have been developed in the field of Geographic Information Systems (GIS) through which hydrogeomorphologic studies can be conducted. In recent years GIS has emerged as a powerful tool in analysing the various aspects of groundwater occurrence.
The factors like lithology, structure, geomorphology, slope, drainage and land use/land pattern largely control the groundwater resource of any area. All these factors can be studied and analyzed as thematic layers using a Geographic Information System (GIS). This makes it easy to delineate the groundwater prospect and deficit zones.
The main advantages of GIS in hydro geomorphological studies are as follows:
- A large volume of data can be analysed and integrated using GIS.
- Manipulates and analysis the individual layer of spatial data.
- Rapid, accurate and cost-effective tool
- GIS is a powerful tool for the generation of hydro geomorphological mapping.
Applications of Hydrogeomorphology
The application of hydrogeomorphology can be seen in the planning and management of various activities on the earth’s surface. Some of the important applications of hydrogeomorphology are as follows:
- The accurate, detailed, timely and reliable data on the extent, location and quality of land along with water resources and climatic characteristics helps resource planners in agricultural land use.
- Data on land potential and conservation requirements through hydrogeomorphological studies help in improving the quality of the land.
- Hydrogeomorphological studies are found helpful by environmentalists in identifying hazards and studying climate change.
- Geologists have found it helpful in examining the role of surface and subsurface flow regimes and flow paths on fluvial erosion and mass wasting.
- Ecologists found it helpful to describe the linked water and geomorphic conditions that define habitats in wetlands, rivers and other environments.
- Watershed management depends on collecting and managing information on the physical relationship between vegetation, soil and water resources, which can easily be done by hydro geomorphological studies.
Future of Hydrogeomorphology as Geosciences
Over the years, the relationship between the physical and human environment has taken new turns and shapes over the years. The need for the new subfield called hydrogeomorphology stems from the emergence of various challenges resulting from the growing human population combined with its effects on environmental and water resource systems.
Transformation in the hydrological cycle, water use, land use and climate results from this change in the man-environmental relationship. In today’s era, hydro geomorphological studies are a great option for managing and controlling environmental problems.
In recent years hydrogeomorphology has become an important branch of geosciences to tackle natural hazard impact, environmental auditing, resource assessment and impact assessment. Hydrogeomorphology has developed close relationships with various fields like ecology, soil science and pedo geomorphology to deal with the new challenges.
The growth in the importance of hydrogeomorphology as geoscience can be seen in the fact that now, world organisations like UNDP and World Bank have added a clause of understanding the hydrogeomorphology of the area before starting any development project into it. These organisations have emphasised having detailed knowledge of landforms, hydrogeology materials, and earth surface processes to be utilized or the remedial work, planning framework and land zoning plans.
Thus, hydro geomorphological knowledge is now being utilized in the planning and development of the earth as a whole. This shows the growth in the status and responsibility of hydrogeomorphology in recent years as an important field of geosciences.
Read More in Geomorphology
- Earth Movements: Meaning and Types
- Epeirogenic Earth Movements
- Orogenic Earth Movements
- Cymatogenic Earth Movements
- Concept of Stress and Strain in Rocks
- Folds in Geography
- Fault in Geography
- Mountain Building Process
- Morphogenetic Regions
- Isostasy: Concept of Airy, Pratt, Hayford & Bowie and Jolly
- Continental Drift Theory of Alfred Lothar Wegener (1912)
- Plate Tectonics: Assumptions, Evidences, Plate Boundaries and Features Formed
- Volcanoes: Process, Products, Types, Landforms and Distribution
- Earthquakes: Processes, Causes and Measurement
- Plate Tectonics and Earthquakes
- Composition and Structure of Earth’s Interior
- Artificial Sources to Study Earth’s Interior
- Natural Sources to Study Earth’s Interior
- Internal Structure of Earth
- Chemical Composition and Layering of Earth
- Weathering: Definition and Types
- Mass Wasting: Concept, Factors and Types
- Models of Slope Development: Davis, Penck, King, Wood and Strahler
- Davis Model of Cycle of Erosion
- Penck’s Model of Slope Development
- King’s Model of Slope Development
- Alan Wood’s Model of Slope Evolution
- Strahler’s Model of Slope Development
- Development of Slope
- Elements of Slope
- Interruptions to Normal Cycle of Erosion
- Channel Morphology and Classification
- Drainage System and Drainage Pattern
- River Capture or Stream Capture
- Stream Channel Pattern
- Fluvial Processes and Landforms: Erosional & Depositional
- Delta: Definition, Formation and Types
- Aeolian Processes and Landforms: Erosional & Depositional
- Desertification: Definition, Problem and Prevention
- Glacier: Definition, Types and Glaciated Areas
- Glacial Landforms: Erosional and Depositional
- Periglacial: Meaning, Processes and Landforms
- Karst Landforms: Erosional and Depositional
- Karst Cycle of Erosion
- Coastal Processes: Waves, Tides, Currents and Winds
- Coastal Landforms: Erosional and Depositional
- Rocks: Types, Formation and Rock Cycle
- Igneous Rocks: Meaning, Types and Formation
- Sedimentary Rocks: Meaning, Types and Formation
- Metamorphic Rocks: Types, Formation and Metamorphism
- Morphometric Analysis of River Basins
- Soil Erosion: Meaning, Types and Factors
- Urban Geomorphology: Concept and Significance
- Hydrogeomorphology: Concept, Fundamentals and Applications
- Economic Geomorphology: Concept and Significance
- Geomorphic Hazard- Earthquake: Concept, Causes and Measurement
- Geomorphic Hazard- Tsunami: Meaning and Causes
- Geomorphic Hazard- Landslides: Concept, Types and Causes
- Geomorphic Hazard- Avalanches: Definition, Types and Factors
- Integrated Coastal Zone Management: Concept, Objectives, Principles and Issues
- Watershed: Definition, Delineation and Characteristics
- Watershed Management: Objective, Practice and Monitoring
- Applied Geomorphology: Concept and Applications