The Geographic Information System (GIS) is a surveying system that is designed for capturing, storing, manipulating, analyzing, managing and presenting of all types of either geographical or spatial data. It is a collection of the system used for collection, manipulation and analysis of geographic information. GIS can be used to refer to a number of processes, technologies and methods. The use of GIS in the management of water resources has been in recognition since time immemorial. GIS, when coupled with other survey methods such as the Remote Sensing, are useful in providing a profound solution for future planning and management of water as a resource.
1. GIS as a tool for Water resource management.
As an environmental analysis tool, the value and use of GIS in the management of natural resources such as land, minerals, forests and water bodies are immensely expanding every day. The GIS has a high efficacy in displaying geo-referenced data layers. Such data can efficiently and accurately be used in planning and management of water resource. With the current scarcity of water in most parts of the world, there has been a lot of programs and projects on the sustainability of water resource management. All these would, therefore, require a lot of parameters; quantification, surveying of the land and distribution of water sources and catchments and the targeted area and population among other factors. Therefore, it is for this reason that GIS has been proven very effective in water resource management due to its comprehensiveness. The inevitable nature of the increasingly severe shortage of water due to drastic climatic changes has pushed the stakeholders to seek any possibility out of this menace (Singh, Samaddar& Srivastava2010, 441).
Geographic Information System as a resource management tool offers the planners and stakeholders a variety of simple to use yet valuable applications that are so helpful in studying the distribution of the natural resources. In addition, it also enables planning and measuring of environmental changes such as drought and floods among others. Such environmental changes are usually vital in assessing the relationship between the expected objectives versus the reality on the ground. The capability of GIS to successfully integrate the massive data amounts into an understandable map representation has proved it as a huge tool for many geoscientists. Although analysis of hydrological processes has been regarded as a complex undertaking that can bring forth a set of technicalities, GIS makes such studies possible. Due to its innumerable applicability, GIS is expected to be completely integrated into assessment and management of global water resource (Singh, Samaddar& Srivastava2010, 441)..
2. GIS Data Models for Water Resource Management
Data models in Geographic Information system are vital concepts that need to be understood by every GIS user. Data models are descriptions of how representation and storage of geographical data will be done. They also organize and standardize the how data variables relate. Therefore, the choice of a good data model that suits the topic is very necessary for a successful data representation and storage. Before choosing a type, factors such as cost should be considered. The most commonly used data model is the spatial data type. Under spatial data model, there are two fundamentally separate and different conceptions; 1. GIS-based models; 2. GIS-based movement models and; 3. And object-based models.
The GIS-based movement model is considered the most appropriate in this study due to a number of reasons. This is the only model that involves flow and transport. For example, the GIS movement model would be useful in the presentation of the flow of the hydrological components as well as the transport and movement of pollutants. However, the underlying implementation of the model entails changing or updating the states. The change process could include fluxes at fixed points and time among others. The GIS-based movement model often changes in the state for the better. The above model has been proved to be best in the presentation of the hydrological catastrophes such as flood and drought. It can be used to capture implicitly and present the hydrological movements. Although the model has a limitation of the lack of explicit representation of other geographical features, it has been tested and found useful in GIS data representation and storage.
3. GIS Data Sources and Datasets
A number of primary ways and secondary ways - companies, entities, and associations- can be used to source and store GIS data in illustrations, maps, and pictorial forms. Some of these organizations are well established that they store the best of the best pictorials. Using the digital photogrammetry method, one can be able to obtain primary GIS data in the form of automated aerial photographs. Remote sensed data has also been used to obtain primary spatial data for use.
Apart from the above primary data sources, there are also a number of secondary sources of GIS data. A good secondary source of GIS data is the well-known Google Earth®. Through their sophisticated cameras, the Google Company have succeeded in compiling, storing and sharing the GIS data in for of pictures, illustrations, and maps. Apart from the Google Company there are also other subsidiary sites and organizations that handle Geographic information that pertains hydrological patterns and distributions. The other viable source of GIS data is the HydroSHEDS. From its suggestive name, this is a mapping product that collects, stores and provides GIS data for both regional and global use in a more consistent style. Its data is usually referenced geographically in either raster or vector format various scales including, watershed borders, river networks, flow accumulations and drainage directions. HydroSHEDS’ data is based on high-resolution elevation quality that are usually retrieved from the NASA’s photography. Other sources of GIS data are Institute for Environment & Sustainability (IES) and GeoNetwork among others (West and Moore2005, 26).
4. Development of maps and outputs using GIS and the processes
The data obtained from the above sources would be so useful when manipulated. The data obtained can be used to develop a database, upon which data can be stored in many forms. Data in a GIS can be represented by an area, a label, a table, a map, a point and a line among others. The map is the most commonly used storage and presentation tool especially for the hydrological features. A map consists of a collection of lines, point’s labels and areas. After obtaining a GIS data and its manipulation, the data can be converted to the digital data format. The term size just refers to the logical structure in which the geo-information is stored in a GIS file, then presented digitally. Transfer formats are commonly designed in order to input and bring out data out of any GIS software of interest. In the GIS software, data is usually converted from a digital format to graphic data for presentation. Some of the data formats include the Vector and Rasta formats. In vector formats, the data formatting is based on vector technology.
Vector formats are some of the most complex formats as they entail many ways of storing and presenting coordinates, attributes, database structures, attribute linkage, and information presentation. Some of the notable examples of vector formats include; AutoCAD files, ARC/INFO coverage and Arc Export among others (West and Moore2005, 26). On the other hand, the Rasta data format is suited and is being used to store image information like aerial photographs and scanned paper maps. Moreover, Rasta is the format that is being used by airborne imaging gadgets such as the satellite for data capturing. Rasta formats include the US Federal government’s Spatial Data Transfer Standard (SDTS), Digital Elevation Model (DEM) and US Defense Mapping Agency’s Arc Digital Rasta Graphics (ADRG).
5. GIS analysis steps
In GIS, there are five basic steps that should be followed to ensure an effective process of GIS analysis. In the first step that entails framing of the question, the project initiators frame questions that would help them achieve their goals. In this study, the questions would solely revolve around the hydrological issues of concern. Therefore how you frame a question is a predetermining factor of how effective the following steps will be. The second step is the data exploration and presentation stage. Although this step can be time-consuming, it requires one to explore thoroughly and come up with the most effective one. However, bear in mind that some of the datasets have strict restriction for any commercial use and would require one to pay for them.
After exploring and preparation of data, choosing of the analysis method is the next step. Any analysis method depends on the questions that were framed in the first step a good analysis method should clearly help in answering these questions comprehensively. After choosing an analysis method, analysis performing is the next step that follows. Making of analysis entails critical scrutiny of the information gotten while drawing out some facts of interest. Lastly, refining and examining of the results is recommended as this will ascertain and sieve out any possibility of error that would have arisen in the analysis. It entails reconciling and auditing of the results.
6. Problems Limiting GIS use in Hydrology
As much as GIS has been found to be so useful in the management of water resources, it has suffered setbacks due to a number of issues. Some of the personnel in the Water resource management have considered is too expensive to employ GIS in the management of hydrology. Therefore, this sweeping notion of the cost has made it too hard to adopt. For a GIS system to be adopted in a company, the personnel are supposed to be taken through rigorous training, which, in the long run, requires time and money (Sipes2006, 57). Due to this, applying GIS in water resource management has been a nightmare. Some of the instruments and tools used in GIS are way too sophisticated to be purchased anywhere. This has limited use of GIS only to those entities that are either close to the source or those with sufficient money to afford such equipment like cameras. Therefore, a lot has to be done for GIS use in water resource management to be effective.
In conclusion, GIS is a good tool that when adopted in water resource management, a great extent of development can be achieved effectively. With its best techniques and outs, GIS has the best on the ground to offer in effective resource management. However, it is still facing a number of limitations that when well addressed, the impact of using GIS can be extended within a short span.
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Gallery if GIS Images
Gallery 1: A satellite picture of drainage system representing 100-500 year flood plains (Courtesy of ArcUser Summer, 2004)
Gallery 2: A contours showing water conductivity in a rice field in Pakistan. (HydoSHED, 2009)
Gallery3 : A sanapshot of Arc Digital Rasta Graphics (ADRG) in use.
Gallery 4: Use of maps and charts in GIS data presentation