In this study, multi-criteria analysis was used to identify suitable locations for dam site based on Streams order, slope, soil texture, land use/land cover (LULC), and geology. These parameters were assessed by different tools. After that, weights for each criterion were assigned by using AHP and weighted overlay was run to generate the suitability site selection for dam.
3.1 Hydrological Network
In a Geographic Information System environment, a reservoir modeling approach was applied where SRTM DEM was used to delimit the Kurram River basin in the study area. Strahlers law describes the flow sequence and we draw out the drainage network of the Kurram river basin. Similarly, the slop map created from Digital Elevation Model in the ArcGIS and the slope was classified from higher to lower degree value. The Digital Elevation Model himself is deliberated an elevation layer divided into five classes. The satellite image is prepared and categorized by consuming a supervised image classification method. The land use and land cover map is created in five classes, containing agriculture, built up, water bodies, barren land, and mountain. Geological map is digitizing and after keep as raster layers and the geological map is classified into five classes. In addition, the “Euclidean distance” tool in “ArcGIS” creates distance zones away from flows and the level is used later in place of the order of the flow itself and the distance from stream is classified in to five classes. Euclidean distance layer is called the reciprocal variable of the flow order. The classification of each criterion is based on expert opinion, GIS experts, literature, geographers and geologists.
3.2 Digital Elevation Model (DEM)
In the Geographic Information system GIS environment the watershed modelling techniques was applied by consuming the SRTM Digital elevation model to define the Kurram River basin in the Kurram Tangi, North Waziristan district. The Strahlers law explain the stream order and we have extracted the drainage system of the basin of the Kurram River in the study area. The elevation of the DEM is categorized into the five classes as shown in the (Fig. 3) in the Digital elevation model map. Give the suitability rank such as highly suitable, moderately suitable, less suitable, and least suitable and not suitable.
3.3 Stream Order
This is a result where the stream system is assigned a numerical imperative. This technique is used to identify and rank flows that have been created based on the number of branches. The Stream Direction tool admits input from the linear stream raster system, identify the direction of the input raster stream created by the Stream Direction tool, and consequently the output raster makes the consequent stream order. The stream order is categorized into five orders as shown in the (Fig. 4) of stream order map. Giving suitability rank to the stream order such as 1st order not suitable, 2nd order least suitable, 3rd order less suitable, 4th order moderately suitable and 5th order high suitable.
3.4 Distance from Stream
In ArcGIS the Euclidean distance tool is consumed to make distance zones from streams. Euclidean distance layers are known as the common parameter of the stream order. The distance from stream is categorized into five classes and the unit of the categorized classes in meter (m) as shown in the (Fig. 5) in the distance from stream map. Giving suitability rank to the classes such as highly suitable, moderately suitable, less suitable, least suitable and not suitable.
3.5 Slope
In ArcGIS the slope map was made from the Digital elevation model. The slope degree was categorized from high to low values, and the values from high to low are ranked as the degree unit as shown in the slope map of the study area in the (Fig. 6).
3.6 Land Use and Land Cover
The Land Use and Land Cover map was develop and categorized into five classes and the five classes contain the agriculture, barren land, water bodies, built up land and mountain of the study area as shown in the (Fig. 7) in the land use and land cover map. Giving Suitability ranks to the barren land highly suitable, water bodies moderately suitable, mountains less suitable, built up least suitable and agriculture not suitable.
3.7 Soil Texture
The soil texture map contains the different types of soil of the study area. The soil texture map categorized into six classes such as the loamy and clayey, part (no calcareous soils ustrochrepts, hoplustalfs, and ustorthents with some ustifluvents/ ustipsamments) of alluvial or loes plains/ terraces and the second is loamy and clayey, part saline soil (comborthids and torrifluvents with some solarthids/ haplatorrerts) of piedmont plains and the third is the mountains: rock outcrops and loamy very shallow soils (xerorthents and xerochrepts) velley, mainly loamy soils (xerochrepts and xerothents/ xerofluvents) and the fourth is the loamy shallow soils (ustorthents ustochrepts and haplustolls) and rock out crops valley, mainly loamy soil ustorchrepts and ustifluvents, and the fifth one is the mountains, rock outcrops and loamy very shallow soils (ustorthents and ustochrepts with little haplustoils) valley, mainly loamy soils (ustochrepts and ustorthents/ ustifluvents) and the last one is the mountains, rock outcrops with very patchy cover of heterogeneous soils materials, valley; mainly loamy, part gravelly soils (combarthids, calcierthids and torriorthents) are shown in the (Fig. 8).
3.8 Geology
The geological map was containing the different types of rocks in the study area. The rocks are the piedmont and related deposit, Eocene and Palaeocene sedimentary rocks, cretaceous intrusive rocks, cretaceous and Jurassic sedimentary rocks, alluvium and the alluvium and extrusive mud as shown in the geology map in the (Fig. 9).
3.9 Analytical Hierarchy Process (AHP)
It is describing as a comprehensive tool this participates applied and individual ideas of professionals to accomplished the “decision-making process” by evaluating multiple factors. This technique ranks each assigned factor on a scale of equivalent importance by evaluating every component beside a pairwise assessment. That study calculates the significance of the variables that was affects the potential of the water. The arranged strata are allocated weights consequent from this method and have undergone a weighted overlap analysis. On the pairwise assessment grid, the chain keeps the corresponding value of every variables and its meaning along the 2nd variable. The general pairwise assessment grid is created by stabilizing the pairwise assessment array. Next, the weights are assessed from the “arithmetic mean”. The “consistency index” is evaluated consuming the “corresponding expressions” according to the "Saaty 1980" and the "Analytical hierarchy process” (AHP) table is given below in (table.3.1).
Table 3.1
Weightage Table Analytical Hierarchy Process (AHP)
| Stream order | Slope | Dem | Land use | Geology | Soil Texture | | Nth | Vector |
---|
Stream order | 1.00 | 3.00 | 2.00 | 3.00 | 4.00 | 1.00 | 72.00 | 2.35 | 0.383319664 |
Slope | 0.33 | 1.00 | 2.00 | 3.00 | 5.00 | 1.00 | 10.00 | 1.58 | 0.258282273 |
Dem | 0.50 | 0.50 | 1.00 | 2.00 | 3.00 | 0.33 | 0.50 | 0.87 | 0.141869357 |
Land Use | 0.33 | 0.33 | 0.50 | 1.00 | 2.00 | 0.50 | 0.06 | 0.56 | 0,091419765 |
Geology | 0.25 | 0.20 | 0.33 | 0.50 | 1.00 | 0.33 | 0.01 | 0.38 | 0.06255447 |
Soil Texture | 0.25 | 0.20 | 0.33 | 0.50 | 1.00 | 1.00 | 0.01 | 0.38 | 0.06 |
| | | | | | | | 6.14 | 1 |
Sum | 2.67 | 5.23 | 6.17 | 10.00 | 16.00 | 4.17 | 82.57 | | |
Sum*pv | 1.022185772 | 1.35167723 | 0.874861036 | 0.914197647 | 1.000871525 | 0.260643626 | 5.424436835 | | |
Lambda max | 5.687167844 | | | | | | | | |
Consistency Index CI | | 0.106109209 | | | | | | | |
RI | 1.12 | | | | | | | | |
CR = CI/RI | 0.094740365 | | | | | | | | |
3.10 Suitability map for Proposed Dam Site
The outcomes showed suitability maps for dam locations known as "overall suitability". In the suitability map there are four classes such as "highly suitable, moderately suitable, least suitable and not suitable". The map was acquired by counting in the analysis the Euclidean distance layer as the reciprocal of the current order layer. In the reclassified “Euclidean distance layer”, the distance to streams was divided into four classes, and all variables including slope, elevation, stream order, distance from stream, soil texture, geology and land use, and land cover on the map. The resulting map showed a high suitable area at the bottom of the study area where the flow orders was very low. There is no uncertainty that all other variables have been taken into consideration to find the most suitable area, the lower section with the most appropriate slope. The sources are also suitable for multipurpose purposes, such as for irrigation, Agrarian use, flood protection, hydroelectricity in the study area. The classes show such as the highly suitable, moderately suitable, least suitable and not suitable in the (Fig. 4.10) in the suitability map of the study area. In last obtained suitable site selection for proposed dam in the focused area and indicate the pour point of the calculated dam in the focused area is ground validated from the Google earth images and there is in the focused area the action delay dam is present and with the all aspect and variables choose the multi-purpose dam in the focused area which are shown in the suitability map.