File Name: topography and hydrology analysis and modelling of region by using gis .zip
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Metrics details. This research examines the susceptibility of logged and regenerated forest region to erosion through the application of the analytical hierarchy process AHP and geographical information systems GIS. In order to estimate terrain erosion susceptibility, ten geo-environmental variables were taken into account as possible factors relevant to terrain erosion. Pairwise comparison matrixes were generated to derive the weightages and ratings of each variable and their classes. These were integrated to generate the terrain erosion susceptibility index TESI map.
Groundwater is a vital natural capital for the consistent and economic provision of potable water supply for both rural and urban environments. There is now a strong consensus that climate change poses a fundamental challenge to the well-being of all countries, with potential of being the harshest on countries already suffering from water scarcity.
However, the decreasing trend in the rainfall regime of the dry zones and the increase in population size temporary inflow and, hence, the demand for water for irrigation and other livelihood requirements, calls for a sustainable exploitation of the groundwater resources in the region. The development of a reasonable model for groundwater potential is need for the present time. This work strives to generate groundwater potential zonation map using integrated use of remote sensing and geographic information system GIS for Killinochi area, Northern Sri Lanka.
The final map of the area was demarcated by four different zones of groundwater prospects, viz. The hydrogeomorphological units, such as alluvial plain, low slope area, and land occupied by forest, are prospective zones for groundwater occurrence in the study area.
Water is one of the most essential commodities for mankind and the largest available source of fresh water lays underground. It is one of the most significant natural resources which support both human needs and economic development. The arid and semi-arid areas characterized by short periods of heavy rainfall and prolonged dry periods, the continual replenishment of groundwater storage and its sustainable utilization is indispensable to address the water needs of the community.
On the other hand, the integrated use of remote sensing, GIS, and satellite data is time and cost effective means to assess and manage groundwater resources Adiat et al. Several scientific communities have already reported the importance of different hydrogeological factors, viz.
It is important to consider these factors very precisely with inputs from different scientific experts and field observation. Sri Lankan economy depends on agricultural production. Water availability and demand in Sri Lanka show a highly spatial variability and temporal variability.
Groundwater is the major source of fresh water, especially among the rural communities in the dry parts of Sri Lanka. The groundwater flow dynamics is highly dependent on the hydrogeological formations through which the flow takes place Freeze and Cherry For the dry zones of the Killinochi basin in Northern Sri Lanka, the monsoon and inter-monsoonal periods play the major role in replenishing these ground water resources.
The long civil war between Sri Lankan Government and the Liberation Tigers of Tamil Eelam LTTE has caused significant hardships for the population, social and physical aspects, and the economy of the country Gunawardena After having been displaced by war, residents return to their villages and started their livelihood.
According to the census report by department of census and statistics in Sri Lanka, the population size has jumped from 23, in to , in in Killinochi district Population and Housing data The decreasing trend in the rainfall regime of the dry zones and the increase in population size, and hence the demand for water for irrigation and other livelihood requirements, calls for a sustainable exploitation of the groundwater resources in the region.
The task of estimating the volume of groundwater entering the aquifer system and its spatial and temporal distribution over the domain is very difficult Gupta It is highly demanding, both in terms of manpower and resources, to get reliable information on its availability.
The previous studies have shown that the seasonal available water resource per unit area in the Killinochi district is less than 0. The per capita water withdrawal is among the highest in Sri Lanka for the Killinochi district.
According to a projection by the same study considering the current level of irrigation efficiency, it is expected that by , more regions will fall into water-scarce category Amarasinghe et al.
Sustainable development of the groundwater resources can be considered as the only viable alternative to support the community in the dry areas without depleting the groundwater reserve, mainly to improve their livelihood by maximizing agricultural output. With aforementioned background information, present work attempts to generate groundwater potential zonation map based on five thematic layers, viz. These five thematic layers are taken into consideration after deep literature review and because of only available data along with field expert advice.
The result is validated with observed seasonal hydraulic head map. There are two distinct seasons: wet and dry. January and May are the coolest and hottest months, respectively. Most of the rainfall occur during the Maha season, which occur from October to January and bring rain to the northern and eastern regions of Sri Lanka. The dry season Yala season varies from May to September Bandara Although rainfall amount is quite enough for this small area, because of temporal asymmetry and poor water resource management policies, there is water scarcity especially in the dry period.
Hence, the poverty in the area can be mainly attributed to the war that resulted in the destruction of most of the infrastructure in the district. As the war displaced residents return to their villages, competition for the already scarce water resource is expected to grow sharply. According to the national census data, the population has quadrupled from 23, in to , in Wikipedia. To generate groundwater potential zonation map, a multiparametric data set comprising remote sensing data and conventional maps, including topographic sheets, provided by survey of Sri Lanka were used.
Remote sensing data were used directly for thematic map generation, as they are already in digital format. Five different themes of information, viz. Map of geomorphology, geology, and soil type were extracted from existing topo sheet and maps with a scale of , developed in Thomas et al.
These maps were further updated using satellite data. To generate groundwater potential zonation map of the area, all five different thematic layers were integrated with weighted overlay in GIS. Each thematic map was assigned a weight on a scale of 1 to 5 depending on its influence on the groundwater development both storage and movement of groundwater. Different features of each theme were assigned rank on a scale of 0 to 9 according to their relative influence on the groundwater development.
To differentiate groundwater potential zone, scored maps of all the five thematic layers after assigning weights were integrated overlaid step by step using spatial analyst tool of ArcGIS. The total weights of different polygons in the integrated layer were derived from the following equation to obtain groundwater potential index Rao and Briz-Kishore :.
Here, GWPI is a dimensionless quantity that helps in indexing probable groundwater potential zones in the area. The resultant map was classified into good, moderate, and poor zones. The results were validated using hydraulic head maps groundwater depth of the area using observed field data.
Hydraulic head map is generated by the inverse distance weighting method. Flow chart for the methodology adopted in this work is shown in Fig.
Methodology adopted for the generation of groundwater potential map in Killinochi area, Sri Lanka. Visual interpretation of digitally enhanced images enables identification of the geomorphologic features. Geomorphology of an area gives the information about description and genesis of its landforms, which depends upon the structural evolution of geological formation Gupta In other way, geomorphologically, the area depicts both its erosional and depositional landforms.
Among five different thematic layers, geomorphology was assigned highest weight, because it plays dominant role in the movement and storage of groundwater at any place Thomas et al. In this study area, geomorphological map is composed of five major units, as shown in Fig. Geomorphologically, the study consists of structures formed in both coastal and continental environments. Beach ridges, bars, and splits: Beach ridges, bars, and splits are morphological signature of coastal environment typically found in the north and west parts of the study area.
Here, beach ridges are the coastal barriers which migrate landward in response to changes in sea level, changes in sediment supply, and changes in coastal erosion that result from tectonic uplift or subsidence.
They are the transitional zone from terrestrial to marine processes with bi-directional flows. Bar-like structure form here, because of high seasonality in the area. High energy storms during winter cause beach erosion, while beach construction occurs during fair weather conditions summer months.
Low plantation surfaces with inselbergs and thin soil: These structures found in south of the study area and represent erosional remnants of oldest plain surface marked by domes of Vijayan gneiss and quartzite. Because of high slope and relief, they are not suitable for groundwater exploration. They consist of relatively flat terrain that is raised significantly above the surrounding area with some steep slopes. They exhibit characteristic island karst features. Because of high hydraulic conductivity, they are considered as very good sites for groundwater exploration.
River plains and adjacent coastal lowlands: Natural stream of fresh water fed by its tributaries flows along a definite course into the sea. Because of the flat topography, this region has high groundwater potential.
Geology also plays major role in groundwater occurrence in any area. Here, the study area is occupied by five major features Fig. Alluvial and lagoonal clay, silt, and sand: Alluvial is the depositional structure formed by running water from all different basins in Killinochi area.
Lagoons are bodies of water on the landward side of barrier islands near the coastal region. Both of these places contain finer sediments with grain size varying from clay to sand and poor sorting order.
Area is considered moderately well for groundwater exploration. Chamockitic biotic gneiss: Here, charnockite represents a conformable intrusive igneous rock which with biotite gneiss was subjected to high-grade metamorphism. Charnockite and surrounding gneiss have layer structure composed of melanocratic and leucocratic parts.
Mineralogically, melanocratic parts consist of hornblende and biotite in gneiss, and orthopyroxene added in charnockite. Leucocratic parts are composed of biotite and colorless minerals in gneiss, while biotite is absent in charnockite. Jaffna limestone: Jaffna limestone is typically a compact, hard, partly crystalline rock formed in the early Miocene age.
The limestone is a creamy colored hard compact, indistinctly bedded, and partly crystallized rock. It is massive in parts, but some layers are richly fossiliferous into a honeycombed mass. Easily, soluble limestone gives rise to a number of underground solution caverns. The limestone is an important aquifer, and, together with thin sand layers, forms an extensive cover providing a source of drinking water and irrigation across the area.
In the study area, it is of red and brown colored. These rock formations usually allow easy percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers.
Undifferentiated Vijayan gneiss with trend lines: They are mainly granitic rocks composed of garnet and feldspar with very low porosity. They are considered as poor aquifers zones. Slope is one of the important terrain parameters expressing the steepness from the ground surface which provide important information on the nature of geologic and geodynamic processes operating at that regional scale.
In the elevation raster, slope is calculated by the identification of maximum rate of change in value from each cell to its neighboring cells. Higher value of slope resembles to steeper terrain, whereas the lower slope values indicate the flatter terrain or surface. The result shows that elevation decreases from the south to north and east to west parts to the study area. Soil is an important factor for delineating the groundwater potential zones.
The climate, physiography, and geology characterize soil and play an important role in groundwater recharge and runoff. The water holding capacity of the area depends upon the soil types and their permeability.
The hydrological cycle is also known as the water cycle, describing the phenomenon of the water recycling system on the earth, which is in the oceans, atmosphere, land surface, biosphere, soil and groundwater systems. There are several stages of the hydrological cycle that occur on this earth, including evaporation and transpiration, precipitation, run-off and watershed processes Narasimhan , Marshall , Inglezakis et al. Water contained in the sea and land surface can evaporate into the air and move up into the atmosphere directly and through vegetation as a process of evaporation and transpiration, that occurs condensation, clouds, and rain as a process of precipitation. Rainfall that falls to the ground surface becomes run-off, and also some water will be infiltrated into the ground and become ground water. A watershed is an area that is bounded by surface topography and also drainage or river patterns. Rainfall that accumulates into the watershed will flow through drainage or river to an outlet on the surface of the earth Marshall , Muharomah Furthermore, the characteristics and conditions of a watershed in an area can be explained by a geomorphological approach.
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A geographic information system GIS is a conceptualized framework that provides the ability to capture and analyze spatial and geographic data. GIS applications or GIS apps are computer-based tools that allow the user to create interactive queries user-created searches , store and edit spatial and non-spatial data, analyze spatial information output, and visually share the results of these operations by presenting them as maps.
Geographical Information Systems in Hydrology pp Cite as. In this chapter the rainfall-runoff phenomenon is considered emphasizing the role assumed by the runoff production. Through the use of GIS, capable of managing and storing a great amount of data, different mechanisms of runoff production are analyzed. In particular a modified and spatially distributed version of TOPMODEL, which is capable of modeling both infiltration excess and saturation excess runoff and incorporating the spatial variability of soil, topography and rainfall, had been applied to simulate the hydrological behavior of an experimental basin Turbolo Creek — Southern Italy Finally, through geostatistical analysis, the spatial distribution of soil parameters is considered to obtain useful information on the characteristic dimension of the elementary drainage area. Unable to display preview.
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