Understanding of Morphometric Features for an Adequate Water Resources Management 1 in Arid Environments

11 The current research investigates the significance of remote sensing data to evaluate the 12 fluviological features and to identify the morphometric parameters of Yalamlam basin, West of 13 Saudi Arabia. Hydrological characteristics, such as topographic parameters, drainage attributes, 14 and the land use, land cover pattern were evaluated for the water resource management of the 15 watershed area. Under GIS environment, the delineation of the watershed and the calculation of 16 morphometric characteristics using ASTER GGDEM was undertaken. The drainage density of the 17 basin has been estimated to be very high which indicates that the watershed possesses high 18 permeable soils and low to medium relief (Hadley and Schumn 1961). The stream order of the 19 area ranges from first to sixth order showing semi dendritic and radial drainage pattern that 20 indicates the heterogeneity in textural characteristics and is influenced by structural characteristics 21 in the study area. The bifurcation ratio (Rb) of the basin ranges from 2.0 to 4.42 and the mean 22 bifurcation ratio is 3.84 of the entire study area that signifies that the drainage pattern of the entire 23 basin is much more controlled by the lithological and geological structure. The elongation ratio is 24 0.14, which indicates that the shape of the basin belongs to the narrow and elongated shape. Land 25 Commented [R.1]: Unnecessary text Commented [R.2]: Are essential to evaluate Commented [R.3]: In the current study


Introduction
The choice of an optimal interpolation method, for the prediction of soil properties at unsampled locations, is a subject of great importance in agricultural management studies.Several attempts had been made in order to specify the most accurate interpolation technique for the generation of continuous soil attributes surfaces.
Most of the soil studies using interpolation techniques include the Inverse Distance Weighted and Kriging methods.The accuracy of these methods has been compared in several studies.Gotway et al. (1996) found that the IDW method generated more accurate results for mapping soil organic matter and soil NO3 levels.Wollenhaupt et al. (1994) compared these two interpolation techniques and concluded that IDW was more accurate for mapping P and K levels of soil.Mueller et al. (2004) observed that for the optimal parameters of the method, the accuracy of IDW interpolation generally equaled or exceeded the accuracy of kriging at each scale of measurement.On the other hand, other researchers observed Kriging to be more accurate for the interpolation of soil attributes.Leenaers et al. (1990) found Kriging interpolation method the most accurate in comparison to IDW, for mapping soil Zn content.
Other studies compared Kriging IDW and Radial Basis Functions interpolation techniques in soil science.Schloeder et al. (2001) observed that Ordinary kriging and inverse-distance weighting were similarly accurate and effective methods, while thin-plate smoothing spline with tensions was not.Weller et al. (2007) resolved that not only the predications for kriging were not satisfied the kriging method, but also was as good as any other radial base function interpolation.
Since the early decades of the century, spatial variability of soil properties has been widely studied in order to understand the behavior of soils for agricultural purposes.Knowledge, of spatial variability and relationships among soil properties, is important for the generation of soil maps for reasons of land management.
Hydrological parameters are essential for adequate water resources management plans.
Morphometric characteristics aim to investigate the watershed delineation, site selection in water recharge and discharge, run off modelling and other geomorphological studies (Sreedevi et al., 2013;Elhag, 2015).GIS helps a wide variety of basin characterization and evaluation applications under different terrain conditions (Pankaj and Kumar, 2009;Magesh et al., 2011).
Digital Elevation Model (DEM), such as ASTER GDEM (USGS, USA) is the keystone involvement in various extractions of Geo hydrological parameters of the watershed.Several parameters including slope, aspect, stream network, and upstream flow areas can be conducted from the DEM characterization (Grohmann et al., 2007;Elhag, 2015).Reliable results of implementing Remote sensing and GIS based morphometric evaluation using ASTER GDEM data have been reported in numerous scholarly work of watershed characterization (Farr and Kobrick, 2000;Panhalkar, 2014;Elhag, 2015).Author's refers that ASTEDR GDEM is more useful and The conducted results of the current study discuss that the analysis of methodical information and further hydrological and morphometric investigation can find out satisfactory alternative strategies for adequate rainwater harvesting based on observed calculations in the designated study watershed.The main aim of the present study is to identify and investigate various drainage attributes to geometrical evaluation of Yalamlam basin for the sustainable rainwater harvesting management and conservation of water resources.

Study Area
Wadi Yalamlam basin is located about 125 km southeast of Jeddah city and is bounded by latitudes 20° 26′ and 21° 8′N and longitudes 39° 45′ and 40° 29′E (Figure 1).Wadi Yalamlam basin drained large catchment area of about 180,000 hr.The basin boundary of the lower part is enlarged to include nearly all the flat area in the downstream part.Wadi Yalamlam basin is initiated from high elevation Hijaz escarpment with mean annual rainfall of about 140 mm.The basin elevations are greatly varies from upstream and downstream parts and range between 2850 m and 25 m (a.s.l.) respectively.The main course of Wadi Yalamlam is crosscut the highly fractured granitoids, gabbroic and metamorphic rocks until the coastal plain of the Red Sea.The upper and middle parts of Wadi Yalamlam basin are covered by intense natural vegetation.The lower part is covered mainly by Quaternary deposits and sand dunes with small-scattered highly altered granitoids and metamorphosed basaltic hills.Several basic dykes are recorded in the lower part of Wadi Yalamlam basin.The thickness of Quaternary wadi deposits increased in the lower part (Elhag and Commented [R.13]: unnecessary text Commented [R.14]: misplaced, its good for conclusion Bahrawi 2017).Regional groundwater flow drains toward the south and southwest following the general trend of the main wadi channel.The gradient of the water table varies from one area to another according to the variations in the pumping rates and hydraulic properties of the aquifer.It

Soil sampling
Map accuracy and quality depends on the sampling method to be used, scale, analytical laboratory errors and prediction errors.Sampling approaches depend on the objectives of the study that are highly correlated to scale.Random Stratified Sampling was the adopted sampling design, the landscape is divided into smaller areas, named strata, and afterwards 150 random samples are taken from the designated study area.

Physical and Chemical soil analysis
Each individual sample was analyzed separately and each measurement was repeated three times for the same extract.Thus, the final values of the measured attributes are represented by the mean value of nine measurements.Soil samples were analyzed in order to estimate physical analysis (clay, silt and sand) and chemical analyses (pH, Calcium Carbonate, Electric Conductivity, Minerals and Organic Content) including all samples.
For standard particle size measurement, the soil fraction that passes a 2-mm sieve is considered.
Laboratory procedures normally estimate percentage of sand (0.05 -2.0 mm), silt (0.002 -0.05 mm), and clay (<0.002 mm) fractions in soils.Soil particles are usually cemented together by organic matter; this has to be removed by H 2 O 2 treatment.However, if substantial amounts of CaCO 3 are present, actual percentages of sand, silt or clay can only be determined by prior dissolution of the CaCO 3 .
The chemical procedures presented here are extensive, though by no means exhaustive.For any given element, there are several procedures or variations of procedures can be found in the literature (Walsh and Beaton, 1973;Westerman, 1990).Procedure for determining soil pH in a 1:1 (soil: water) suspension was after McLean (1982).The methodology of EC measurement is given in USDA Handbook 60 (Richards, 1954).Active CaCO 3 is usually related to total CaCO 3 equivalent, being about 50% or so of the total value.Total CaCO 3 , is currently estimated after Drouineau (1942).Geostatistics interpolation is based on the assumption that all values of a variable that is measured are the result of a random process.The phrase "random process" does not indicate that all events are independent.More specifically Geostatistics is based on random processes with dependence, otherwise called autocorrelation, and relies on some notion of replication.Repeated observations in nature can result in understanding the variation and uncertainty of natural phenomena, and furthermore in estimating their sequence in space and time.Three interpolation techniques were used for the generation of the prediction maps (interpolation).Inverse Distance Weighted (IDW),

Interpolation techniques
Radial Basis Function (RBF) and Ordinary Kriging (OK) method were compared according to the accuracy of the results.
Trend and random error equation (Johnson and Riess, 1982) The symbol s stands for the location of the prediction location.Z(S) is the variable you are predicting (total extractable heavy metal concentration).μ(S) is the deterministic trend.ε(S) is the spatially-autocorrelated random error.Based on the foundation scholarly work of Horton (1945), Schumm (1963), Strahler (1964) and others, several morphometric parameters were performed and computed utilizing ASTER GDEM under GIS environment.Consequently, watershed delineation, stream network identification, drainage frequency, drainage density, shape, elongation ratio, circularity ratio and form factor were computed and evaluated using 30m spatial resolution of ASTER GDEM.The methodologies adopted for the evaluation and computation of morphometric features are given in Table 1.

Supervised classification
Remote sensing data was obtained from Landsat Operational Land Imager (OLI-8) which is acquired on June 10 th , 2013.Typical atmospheric and radiometric corrections and spatial resolution enhancement were implemented for each band individually.Furthermore, supervised classification was implemented using Support Vector Machine (SVM) classifier for better classification results (Psilovikos and Elhag, 2013).The final step in the digital image analysis is the evaluation of the accuracy of the computer derived classification results.These results are often expressed in tabular form, known as a confusion matrix (Elhag et al., 2013).The SVM classifier is implemented as: Where: g is the gamma term in the kernel function for all kernel types except linear r is the bias term in the kernel function for the polynomial and sigmoid kernels.

Results and Discussion
Quantitative evaluation of the watershed through the analysis of morphometric parameter can provide significant information about the hydrological characteristics of rocks, which are exposed within the basin.The nature of drainage of a basin reveals reliable information about the permeability of the rocks and the yield of the basin.
The ASTER GDEM has been collected with 30 m resolution and the GDEM has been used to generate watershed area, aspects and slope map of the basin.The drainage network of a basin depends on endogenous forces and exogenous forces.Geology and precipitation pattern of the study area.ASTER GDEM was used for preparing aspects, slope map of the basin.Areal, relief and linear aspects of the basin were analyzed under GIS environment.Currently a geospatial technology has been given more precise and accurate information through the evolution of morphometric parameter for the assessment of drainage watershed.GIS technology and satellite data have been used to formulate data on spatial deviations in drainage attributes.Therefore, drainage parameter provides a significant insight into hydrological characteristics, which is more important to develop the watershed management strategies (YanYun et al., 2014).
Evaluation of drainage characteristics and other morphometric parameter of Yalamlam basin has been undertaken to calculate the parameter and built topology of the basin.Different type of Arial and linear aspects and their characteristics has been calculated, these aspects are, basin area (A), basin length (L), basin perimeter (P), bifurcation ratio (Rb), elongation ratio (Re), circularity ratio (Rc), drainage frequency (Fd) and drainage density (Dd) etc.

Stream order (So) and stream no:
The lower Yalamlam basin encompasses through the basin mega fan, which is formed by ancient and modern radial drainage pattern in the designated study area.The channel of this area is characterized by higher sinuous, decreased widths and lesser discharge capacity as a numerous traverse Paleo alluvial channels (Bahrawi et al., 2016).Therefore, the stream ordering of the study area has been ranked based on Strahler (1964) method and demonstrated in Table 2.

Bifurcation ratio:
The bifurcation ratio was calculated by the no of streams of an order to the no of the streams of the next higher order.The values vary from 2.0 to 4.42 of the Yalamlam streams basin, which is also signified the maximum structural influences (Strahlar, 1964).After the calculation of bifurcation ratio, calculate the average value which is the mean bifurcation ratio is 3.84 of the basins.The value also indicates that the drainage pattern has been affected by structural disturbances within the basin.The obtained no of bifurcation ratio varies from one order to another order.Such variation is interpreted as irregularities of the lithological and the geological development within the watershed.The values of bifurcation ratio and mean bifurcation ratio have been shown in Table 3.

Drainage texture and drainage density:
Drainage density is an expression of spacing and distribution of channels as proposed by Horton (1932) that measure the total length of the streams of all orders as calculated with per unit area.
Relative relief and slope gradient of the river basin primarily control the stream density.The stream density of the watershed has been calculated which is shown in Table 3.The value of drainage density is 0.92 in the study basin.The drainage density has been classified into five kinds of drainage texture as proposed by Smith (1950).
The drainage density more than 8 indicates very fine, the value 8-6 is fine, between 6-4 is moderate, the value 4 to 2 is coarse and less than 2 represent very coarser drainage texture.The observer drainage texture is 0.138, signifies the resistant permeable rock with moderate infiltration rate and moderate relief (Bahrawi et al., 2016).The value of the variation of drainage texture depends on different kind of natural factors that is rainfall and other climatic characteristics, rock, soil type, vegetation characteristics, permeability, relief, infiltration capacity within the watershed.The relationship between the hydrological features and the geological structures is estimated to be with a high drainage density caused by the mountainous relief in the basin.The lower value of drainage density reveals that, the region is composed of permeable sub surface material, low relief, dense vegetal cover which results in the increase of more infiltration capacity in the basin.The value of high drainage density indicates mountainous relief, thin vegetation and impermeable sub surface material, highly resistant rock types in the river basin.

Drainage frequency:
Drainage frequency or stream frequency is calculated by the total no of streams per unit area of all stream orders that proposed by Horton (1932).The correlation value of drainage density and stream frequency is plays positive of the basin, which suggests that the no of streams, population has increases with the increase of drainage density.The observed value of stream, frequency is about of 0.34 for the watershed exhibits the highly positive connection with stream density that has been shown in Table 3.

Elongation ratio:
The elongation ratio is calculated by the ratio between maximum length of the basin and the diameter of a circle, which fitted in the same basin area, as proposed by Schumm, (1956).The elongation ratio value generally varies between 0.6 and 1.0 where a wide variety of geological condition and climatic characteristics has.According to Strahlar (1964) the values close to 1.0 represent the region belongs to very low relief with less structural influences and the value ranges from 0.8 to 0.6 are generally associated with much steep slope and high relief.The values of elongation ratio can be categorized into 3 groups, namely less than 0.7 indicates elongated shape, and 0.8 to 0.9 values represent the oval shape and more than 0.9 values represent the circular shape of the basin.So, the elongated ratio of the study area is 0.14 that suggests that the basin shape is belongs to the much more elongated type (Table 3) of the basin where structural influence is much all over the basin.

Circularity ratio:
According to Miller (1953) circularity ratio is the ratio between the area of a circle, which fitted in the basin perimeter, and the total basin area.Circularity ratio is much more influenced by geological structure, relief, slope, climate, frequency and length of stream and land use land cover within the basin.The basin circularity ratio is 0.08, which represents that the basin is strongly elongated and belongs to the heterogeneous geological structure and materials.The observed values also signify the high run off capacity and low permeable capacity of subsoil and sub-surface soil along the basin area (Table 3).

Form factor:
Horton (1932) defines the form factor as the ratio between the square of the basin length and basin area.The values of form factor represent the flow intensity of the study area.Generally, the elongation shape and the values of form factor have a negative relationship that means the smaller value indicates the more elongated shape of the basin.The values should always be not exceeds 0.7854, higher value of form factor represent the higher peak flows of a higher period.The observed value of form factor is 0.06 of the Yalamlam watersheds signifies the elongated shape of the basin (Table 3).Therefore, the lower values and elongated shaped basin indicates that the watershed belongs to the flatter peak flow of shorter duration.

Relief and relief ratio if the watershed:
Relative relief is the difference between the highest and lowest elevation of the watershed.The relief ratio is the ratio between relative relief and the maximum length of the basin as proposed by Schumm, (1956).It can analyses the steepness of the basin and evaluate the intensity of erosion process of the study area.Here the relief ratio is 4.17, which indicated that most of the designated basin is situated along the mountainous rough slope and much narrower in the lower areas.

Slope map:
Slope is the ratio between horizontal and vertical surface, of a region, which can be expressed by

Geo hydrological Inferences from Morphometric Evaluation:
The classification of Remote Sensing data was to quantify the area of all alluvial deposits to the bare rock area within the designated study area as illustrated in Figure 2. Table 4 indicates that the area of the alluvial deposits is roughly equal to the bare rock area which means that the watershed is the watershed is likely to be used for rainwater harvesting (Elhag, 2014 andElhag andBahrawi 2014 a).The drainage pattern of the basin is sub dendritic and radial in nature.The pattern was affected by more or less heterogeneous structural and lithological characteristics.In addition, high drainage density is observed all over watershed along with very high relief and impermeable subsoils and land rock substratum, mountainous terrain slope.On the other hand, lower riparian areas are low drainage density, which are favorable for the identification of water storage areas and ground water potential zones.However, slope plays a significant role in determining the relation between infiltration rate and runoff velocity where infiltration rate is inversely controlled by regional slope.
So all evaluated parameters are more important to the analysis of future water availability of the study region.
Results obtained from pervious scholarly work of Şen, (1995) pointed out that the average transmissivity values calculated within the study area range from 91 to 147m 2 /day.While the the transmissivity values increase sharply in the downstream area to range between 267 and 731 m 2 /day (average 500 m 2 /day).Such findings support the hypothesis that the aquifer is of high potential therein.On the other hand, the hydraulic conductivity values calculated for Yalamlam basin attain a high hydraulic conductivity (16 m/day) due to more permeable alluvial deposits (Sen, 1995, Elhag andBahrawi 2014 b,c).

Conclusions:
The evaluation of hydrological characteristics of the Yalamlam watershed confirms that the area is having high relief and the shape is elongated in nature.The stream network of the watershed is basically dendritic type in lower portion which indicates the lack of structural influences and the homogeneity of textural characteristics, but the upper portion of the watershed highly influenced by tectonic and structural activity due to the parallel pattern of the drainage network.The drainage characteristics of the basin help to understand the different kind of terrain parameters, i.e, runoff, infiltration capacity and nature of the bedrock etc.The drainage density and frequency of the drainage basin is low that indicates the high permeability rate and well-drained capacity of the sub surface formation.All kinds of basic and derived parameters reveal an important the water recharge areas and measures can be undertaken for the soil conservation structures and water resource management.Therefore, watershed analysis using remote sensing data, GDEM data and GIS techniques has an efficient, precise tool for the understanding of any terrain attributes such as surface runoff, nature of bedrock, and infiltration capacity helps to better understanding of drainage evolution and management of ground water potential and status of landform and their characteristics for watershed management and planning.The study will be useful for water as well as natural resource management of any terrain at the watershed level.For sustainable water resource management and watershed development decision makers and planners can be used these kinds of hydrological analysis.
The thickness of the saturated zone within the aquifer varies from less than 1 m upstream of Yalamlam to about 30 m in the Sa'diyah area.The aquifer is generally unconfined, especially in the upper parts of the wadi.Semi-confining conditions may exist in the lower parts where layers of clay exist.There are about 31 wells in the basin of Wadi Yalamlam, out of which, 23 are handdug wells and the others are drilled.
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