Stream Length Ratio Research Articles

A GIS-based Approach in Drainage Morphometrie Analysis of Sai River Basin, Uttar Pradesh, India

Abstract This study focuses on hydrogeological processes and sub-surface geological activities. The basin area measured is 11,161 km2 with NW-SE sloping trend. Sinuosity Index is 2.7 which show meandering nature. The drainage density, stream frequency and drainage intensity values were 0.62 km−1, 0.23km−1 and 0.37 respectively which implies that low surface runoff, high permeable alluvium, high infiltration rate, easily erodible alluvium and low relief. Mean Bifurcation ratio of 5.11 indicates that the basin is structurally controlled. Stream length ratio shows mature stage of erosion and low runoff. The basin is found to be significantly elongated circularity ratio, elongation ratio, form factor, shape index and shape factor is 0.07, 0.33, 0.09, 4.28 and 11.61 respectively. Drainage texture of 0.15 (km−1) suggest the smooth topography and high drainage density. Relief ratio is 0.23, low surface run-off, low erosion, and gentle slope. The constant of channel maintenance, length of overland flow, ruggedness number is 1.60, 0.80, 0.05 respectively, conclude the gentle slope, low surface runoff, high infiltration rate, least erodible and high permeability. The Rho coefficient of 0.11 shows the low capacity of water. The basin relief is 84 and relief ratio is 0.23 m indicating low run-off and low erosion. Hypsometric curve and integral show that the river is having intermediate stage of incision and erosion, Asymmetric factor, drainage basin shape, presence of high escarpment zones, fall displacement and uplifted barrier occur in the path of the channel identified in the transverse profile, longitudinal profiles due to intra-basinal sub-surface tectonic activity.

Geospatial and Artificial Neural Network Applications for Prioritization of Watershed Prediction

Characteristics of the river basin formed by natural factors and non-natural factors that makes up an ecosystem. One of the characters that create the river basin of the physical element is morphometry. Morphometry has three parameters such as linear, relief, and areal. The linear aspect consist of stream order (U), stream length (Lu), bifurcation ratio (Rb), stream length ratio (Rl), bifurcation ratio (Rb). Relief aspect consists of basin relief (Bh), relief ratio (Rh), ruggedness number (Rn). Areal elements comprise drainage density (Dd), stream frequency (Fs), texture ratio (T), form factor (Rf), circularity ratio (Rc), elongation ratio (Re), length of overland flow (Lg), constant channel maintenance (C). This study aims to analyze the characteristics of watershed morphometry and implement Geographical Information System (GIS) and Artificial Neural Network (ANN) to get watershed priority predictions. After analyze, the prioritization based on morphometry that is six sub-watershed with very high priority, two sub-watershed with high priority, four sub-watershed with medium priority and five sub-watershed have low priorities. From the test results by measuring method using a neural network based, it is known that neural network algorithms yield accuracy values 90.00%, and class precision 90.82 %. The model produced satisfactory results and showed a very good agreement between the predicted and observed data.

Prioritization of Mago Basin based on erodibility through morphometric analysis using GIS technique: A PCA-based approach

Remote sensing (RS) and Geographical Information System (GIS) techniques have become very important these days as they aid planners and decision makers to make effective and correct decision and designs. Geomorphological characteristics of a watershed are commonly used for developing the regional hydrological models for solving various hydrological problems of ungauged watersheds or inadequate data situations. A morphometric analysis of Mago basin of Arunachal Pradesh was carried out using RS and GIS techniques. The Watershed was delineated using ArcGIS10 software and divided into 15 subwatersheds and prioritized based on principal component analysis (PCA) using SPSS 14.0 software. The basic parameters (area, perimeter, stream order, stream length and stream number) of each sub-watershed were carried out separately using the ArcMap10. The linear morphometric parameters (stream order, total stream length and bifurcation ratio); aerial morphometric parameters (drainage density, stream frequency, form factor, circulatory ratio, elongation ratio, texture ratios, compactness constant and Ruggedness number); and relief morphometric parameters (relief ratio, relative relief, average slope and hypsometric integral) were computed with the help of standard formulae. The principal components were selected and then ranked based on their relationship with erodibility. The sub-watershed having the least compound parameter was assigned the highest priority and so on. The study area was found to have streams of highest order of 3, with order 1, having highest frequency. The obtained low drainage density of the basin indicates that the region is highly permeable. From the prioritization analysis, it was found that sub-watershed 2, 4, and 14 were the most erosion prone areas with rank 1. Therefore, these sub-watersheds need to be considered first and given prior importance for the implementation of any soil and water conservation measures for watershed management. Hence, RS and GIS techniques and PCA are important tools in the morphometric analysis and prioritization of watershed.

Morphometric Analysis and Prioritization of Microwatershed of Bisalpur Reservoir using Geospatial Techniques

Limited natural resources and their wide utilization with increasing population is a major concern. Conservation of natural resources is of prime importance for sustainable development and to mitigate the demand and supply gap between resources. Rivers are major source of water, Morphometric analysis of watershed covers the drainage networks and parameters such as drainage area, gradient and relief. Morphometric analysis is significant for prediction of floods, soil erosion and sediment yields. Present study covers linear aspects of Morphometric analysis in Bisalpur Reservoir by using Geospatial techniques. Watershed delineation, flow accumulation, flow direction, Flow length followed by Stream ordering have been accomplished by using Hydrology tool in ArcGIS 10.2.2 Software. Advanced space-borne Thermal Emission and Reflection Radiometer (ASTER) and Shuttle Radar Topographic Mission (SRTM) Digital Elevation model (DEM) have been used for preparation of linear aspects of Morphometric parameters. Drainage characteristic have been calculated such as stream length, mean stream length and Bifurcation Ratio for basin evolution studies, such studies are extremely useful for planning rainwater harvesting and Watershed Management.

Litho-tectonic and precipitation implications on landslides, Yamuna valley, NW Himalaya

ABSTRACT An attempt is made to explain the relationship of landslides to litho-tectonic and precipitation regimes. The possible influence of these factors on the dimensional pattern of landslides is also inferred. The Yamuna River valley, NW Himalaya, which traverses the Higher Himalaya (HH) and Lesser Himalaya (LH) rock mass, endures disastrous landslides and hence is taken as the case for study. To achieve the objectives, proxies like stream length gradient, topographic profile, steepness index, and ratio of valley floor width to valley height were used to infer a spatially varying tectonic regime, whereas rainfall data and Normalized Difference Vegetation Index were used to determine spatial differences in precipitation and vegetation variability, respectively. Dimensional patterns of landslides utilized the landslide area and volume. The higher reaches of the HH and lowest part of the LH show rockfall dominance associated with relatively high tectonic activity, whereas most of the debris slides coincide with regional thrusts. Total area and volume occupied by the landslides are ~1.5 ± 0.16 × 106 m2 and ~4.7 ± 1.2 × 106 m3, respectively. Dimensions of debris slides were found to be less influenced by the litho-tectonic and precipitation regimes, whereas the dimensions of rockfalls were found to be more sensitive to these conditions.

Computation of Watershed Parameters of Kansa Watershed in Satara Using Remote Sensing and GIS

In present study Kansa watershed in Satara district of Maharashtra was characterized for watershed parameters. Geographical Information Systems (GIS) and a high-resolution Digital Elevation Model (DEM) has been utilized for the estimation of morphological parameters. Several morphometric parameters have been computed and analyzed viz. linear aspects such as stream order, stream number, stream length, mean stream length, stream length ratio; areal aspects such as drainage density, stream frequency, drainage texture, elongation ratio, circularity ratio, form factor, constant of channel maintenance; relief aspects such as relief, relief ratio, relative relief, ruggedness number, length of overland flow. Impacts of morphometric parameters on flash flood characteristics have also been investigated. The presence of the maximum number of the first order segments shows that the basin is subjected to erosion and also that some areas of the basin are characterized by variations in lithology and topography. The form factor is 0.21, and the circulatory ratio is 0.42, which suggests an elongated type of catchment. Elongation ratio is 0.52, which indicates that watershed has high relief and steep slope. The estimated catchment characteristics may be useful to stimulate hydrological responses of the catchment.

Computation of Watershed Parameters of Kansa Watershed in Satara Using Remote Sensing and GIS

In present study Kansa watershed in Satara district of Maharashtra was characterized for watershed parameters. Geographical Information Systems (GIS) and a high-resolution Digital Elevation Model (DEM) has been utilized for the estimation of morphological parameters. Several morphometric parameters have been computed and analyzed viz. linear aspects such as stream order, stream number, stream length, mean stream length, stream length ratio; areal aspects such as drainage density, stream frequency, drainage texture, elongation ratio, circularity ratio, form factor, constant of channel maintenance; relief aspects such as relief, relief ratio, relative relief, ruggedness number, length of overland flow. Impacts of morphometric parameters on flash flood characteristics have also been investigated. The presence of the maximum number of the first order segments shows that the basin is subjected to erosion and also that some areas of the basin are characterized by variations in lithology and topography. The form factor is 0.21, and the circulatory ratio is 0.42, which suggests an elongated type of catchment. Elongation ratio is 0.52, which indicates that watershed has high relief and steep slope. The estimated catchment characteristics may be useful to stimulate hydrological responses of the catchment.

Comparative study between rivers in Tarim Basin in northwest China and Evros Vallis on Mars

The morphometric characteristics of the Kaidu River and Keriya River in the extremely arid Tarim Basin, and the Evros Vallis on Mars were compared to study the formation of the dendritic Evros Vallis, which has great significance for exploring ancient climate of Mars. The following results were obtained: (a) the average sinuosities of Kaidu River, Keriya River, and Evros Vallis are 1.17, 1.35, and 1.32 respectively. (b) the average bifurcation ratios are 3.84, 4.73 and 3.43 respectively. (c) the average stream length ratios are 2.21, 3.86 and 2.08 respectively. (d) the stream frequencies are 0.017, 0.028 and 0.002 respectively. (e) the drainage densities are 0.195 km−1 and 0.217 km−1, and 0.048 km−1 respectively. (f) the stream gradients are 3.74‰, 7.03‰ and 1.63‰ respectively. (g) the stream fractal dimensions are 1.70, 1.0 and 1.68 respectively. Paleodischarge estimations at different stream segments of Evros Vallis support the hypothesis that the V-bend area that joints the eastern and western segments possibly has a tectonic origin. Geomorphological evidence (e.g., tributaries) from high-resolution images and stream morphometric parameters from a comparative analysis (e.g., concave upward longitudinal profile and stream fractal dimension) support previous hypothesis that Evros Vallis is a mature drainage system formed by precipitation-driven surface runoff. This drainage process occurred either in a continuously warm-wet climate that lasted long enough on early Mars or in regional hydrologic cycles consisting of precipitation and occasionally returned runoff in intermittently clement climates.

GIS-Based Approach in Drainage Morphometric Analysis of Bharathapuzha River Basin, India

Aims: The paper aims to study about the river basin morphometry namely the physical, linear and aerial parameters for the basin.
 Study Design: The Study has been carried out with the help of Geospatial techniques and statistical formulas.
 Place and Duration of Study: Bharathapuzha river basin, Kerala, India between January 2018 to July 2018.
 Methodology: The Study of River morphometry of Bharathapuzha River basin has been done with the help of SRTM satellite data. The downloaded data has been analyzed with the help of ARC GIS Software. The morphometric analysis has been carried out by dividing the basin into nine watersheds based on Water shed Atlas of India Prepared by Soil and Land Use board of India. Relief, Linear and areal parameters of the basin is calculated with the help of statistical formulas.
 Results: Based on the analysis it is noted that there is not much difference in morphometric values except in some watersheds. Watershed number 5A2B5, 5A2B6 and 5A2B7 has highest drainage density, stream frequency, relief, relief ratio, ruggedness number, stream length ratio and lowest bifurcation ratio. These watersheds are characterized by highest surface runoff and erosion. The values of form factor, circulatory ratio and elongation ratio suggests that most of the watersheds are elongated and has high basin relief. The maximum stream order frequency is observed in case of first order streams and then for second order streams. Hence it is noted that there is decrease in stream frequency as stream order increases.
 Conclusion: The mean bifurcation ratio of the Bharathapuza basin is 1.52 which indicates the whole basin is less effected by structural control. This present study is valuable for the erosion control, watershed management, land and water resource planning and future prospective related to runoff study.

Geomorphic evolution of the Dongar River Basin, Son Valley, Central India

ABSTRACTThe present study is an attempt to describe the geomorphic evolution of the Dongar River Basin, Son Valley, Central India. To achieve this target, a detailed field survey and morphometric analysis of the river have been carried out using Cartosat-DEM data with the help of ArcGIS 10 software. The basin area of the Dongar River is 35.17 km2 having trellis and sub-dendritic to dendritic drainage patterns. The Dongar River is designated as fourth-order basin and lower order streams mostly dominate in the basin with the drainage density value of 1.21 km−1. The stream order of the basin is predominantly controlled by physiographic and tectonic set-up of the study area. The slope of basin varies from 0° to 42.04° and is mainly controlled by the local geology and erosional cycles. The bifurcation ratio (Rb) for the studied basin varies from 1.58 to 4. The higher values of the bifurcation ratio, i.e., of second/third along with third/fourth order, reveal the regional geological and tectonic controls when river starts draining along the exposures of lower Vindhyan . The elongation ratio of the basin is 0.86 thus indicates high infiltration capacity, low runoff, and low-to-moderate slope of the river basin. The increase in stream length ratio from lower to higher order shows that the basin has reached mature geomorphic stage. The major trends of lineaments are ENE – WSW, i.e., almost analogous to Son-Narmada lineament suggesting that Son-Narmada lineament played an important role to control the drainage dynamics and evolution of the adjacent river basins. These features along the Dongar River and the orientation of the major lineaments suggest neotectonics, may be due to reactivation of the Son-Narmada lineament.

Sub watershed characterization and prioritization using geoinformatics for natural resources management

The development of new advanced techniques in Spatial Information such as remote sensing and GIS are effectively used for the extraction of information about spatial features. DEM (Digital Elevation Model) is one of the important sources in extraction of drainage network and is useful for determining the quantitative description of catchment geometry i.e. morphometric analysis. Morphometric analysis has been commonly applied to prioritization of watersheds. In this study, the morphometric analysis and prioritization of seventeen Sub-watersheds of Maniari watershed, situated in Lormi block of Mungeli District Chhattisgarh State, India, was carried out. For prioritization of sub-watersheds, morphometric analysis was performed using the Linear parameters such as stream order, stream length, stream length ratio, basin length, bifurcation ratio, mean bifurcation ratio, drainage density, stream frequency, texture ratio, length of overland flow and shape parameters such as form factor, shape factor, circulatory ratio, elongation ratio, and compactness constant. The different prioritization ranks are assigned after evaluation of the compound factor. Based on the various physical characteristics of the basin, multi-criteria evaluation technique has been used to determine the most suitable water harvesting structure sites. For this purpose hydrologic soil group, slope and stream order data derived. This study confirms about 93 locations classified under the category of highly suitable sites. This mapping helps in selecting potential site for water harvesting structure.

Morphometric analysis and sub-watersheds prioritization of Nagmati River watershed, Kutch District, Gujarat using GIS based approach

AbstractMorphometric analysis of any watershed and its prioritization is one of the important aspects of planning for implementation of management programmes. Present study evaluates the quantitative morphometric characteristics of Nagmati River watershed in Kutch District of Gujarat by utilizing Cartosat-1 data (CartoDEM). In all 19 aerial and 6 linear morphometric parameters of the watershed have been evaluated. Drainage map of the study area reveals a dendritic drainage pattern with sixth order stream network comprising 492 numbers of streams and confining an area of 129.41 km2. Mean bifurcation ratio (Rb) and stream length ratio (RL) of the watershed evaluated are 3.44 and 0.54 respectively which corroborates the fact that drainage pattern is not influenced by the geological evolutions and disturbances in the recent past. The drainage density of 2.68 kmꞏkm−2 indicates impermeable subsoil material with sparse vegetation and moderate to low relief. Elongation ratio of 0.956 infers the basin to be closer to a circular shape. The geologic stage of development and erosion proneness of the watershed is quantified by hypsometric integral (HI) bearing value as 0.5, indicating the landscape to be uniform and in early mature stage. The study prioritizes eight sub-watersheds as high, medium and low for taking up soil and water conservation activities. Hence, remote sensing applications proved to be highly useful in extracting the precise data for the evaluation and analysis of watershed characteristics.

Assessment of morphometric and hypsometric study for watershed development using spatial technology – a case study of Wardha river basin in Maharashtra, India

ABSTRACT The assessable results of the Wardha river basin are essential for the behaviour of the drainage and river network and to know its geology, slope and geo-hydrological condition. The Wardha river basin is covered by 1730.85 sq. km2 with dendritic and sub-dentric drainage patterns. This study area is delineated into nine sub-watersheds from digital elevation model data using Arc hydro tools. The morphometric characters were observed to understand the drainage and watershed characteristics and its impact on groundwater resources for the occurrence of bifurcation ratio that shows very high runoff and low infiltration of groundwater recharge at the basaltic terrain rocks. Slope and topographic maps may be used for groundwater development; theses maps can be used for suitable well points and artificial and ground water recharge sites at the Wardha river basin. The slope values were inversely proportional to infiltration and it has led to the hypsometric analysis using Arc GIS 10.3 software. In this study, different types of morphometric characteristics were measured using computations of linear and areal aspect using geospatial technology domain. The total streams order (3509) has been identified from digital elevation model data. The data show that large numbers of stream are present in this area for scope of water harvesting structures and these play a main role in groundwater development and controlling soil erosion factors. In this study, various morphometric parameter were calculated using mathematical equation and spatial data for understanding of surface runoff, slope, watershed characteristics and watershed condition. Hypsometric investigation has been generally used to reveal the steps of geomorphic growth or land forms. The hypsometric integral value shows nine sub-watersheds observed which shows the mature stage at the Wardha river basin. The hypsometric analysis results have been calculated for watershed and groundwater development. During the study, bifurcation ratio values such as 2.5–4.25 suggest morphological and the basic control for watershed management and drainage network analysis in the area, while drainage density and fine drainage texture suggest its high runoff in basin. The drainage basin characteristics have been made for the assessment of many linear factors such as stream order, stream number, stream length, stream length ratio, bifurcation ratio, drainage density, texture ratio, and stream frequency) and Channel index (Ci) Valley index (Vi), Rho coefficient (q) and Basin Area. All these results may be useful for watershed development programme in the semi-arid area and most influence of basaltic hard rock areas.

Hydro-geomorphological characterization of Dhidhessa River Basin, Ethiopia

Dhidhessa River Basin is physio-graphically and hydrologically important in the Blue Nile basin, however, its morphometry and hydrology are not well known. This study aimed to characterize hydro-geomorphology of the basin via basin morphometry analysis. SRTM DEM, geological and hydrological maps of the area were used in ArcGIS 10.3 environment for this analysis. Results showed that a 33,468 km total stream length of all orders was found distributed within 28,637 km2 drainage area in a dendritic pattern. According to morphometric parameter classification, total stream length and stream order of the basin were high whereas stream length ratio, bifurcation ratio and hydrologic storage coefficient were low. Furthermore, drainage area was large, drainage frequency was coarse, basin shape was more elongated, drainage density was medium, infiltration number was low, overland flow was long and constant of channel maintenance was high. Moreover, the basin's relief, relief ratio, ruggedness number, gradient ratio and the slope was high. In general, the study asserted that the basin was underlain by uniform resistant rocks, less prone to flooding, with high water resources potential and susceptible to soil erosion. The morphometric analysis approach pursued in this study was cost- and time-effective for basin characterization.

Neotectonic Activity from Karewa Sediments, Kashmir Himalaya, India

Intermontane basin sedimentation occurred during Pliocene-Pleistocene in the Karewa Basin which formed after the continent-continent collision resulting in the formation of Himalayan orogenic belt around Eocene. These are elongated, narrow, thrust bounded basins which have formed during the late stages of orogeny. Situated at a height of 1700–1800 m above sea level, the Karewa basin received sediments because of ponding of a pre-existing river system and the tectonic movements along the Great Himalayan Ranges in the north and the Pir-Panjal ranges in the south along active faults. About 1300 m thick sediments of largely fluvio-lacustrine, glacio-fluvio-lacustrine and eolian origin are exposed having evidences of neotectonically formed structural features such as folds and faults. Folds are more prominent in the Lower Karewa formation (Hirpur Formation) while faults (mostly normal faults) are abundant in the Upper Karewas (Nagum Formation). Drainage in the area varies from dendritic to anastomosing to parallel. Anastomosing drainage suggests sudden decrease in gradient while presence of linear features such as faults and ridges is evident by parallel drainage. Study of morphometric parameters such as stream length (Lsm) and stream length ratios (RL), bifurcation ratio (Rb), drainage density (D), form factor (Rf), circularity ratio (Rc), and elongation ratio (Re) also indicate intense tectonic activity in the recent past.

Morphometric Evaluation and Sub Basin Analysis in Hanur Watershed, Kollegal Taluk, Chamarajanagar District, Karnataka, India, using Remote Sensing and GIS Techniques

The study area covers 1026 sq km comprising of 15 sub-watersheds, namely Saggiyam (SB-1), Mudoldoddi (SB-2), Halgapuram (SB-3), Deverabetta (SB-4), Mattugaudanadoddi (SB-5), Handgalli (SB-6), Manchepura (SB-7), Lokkanahalli (SB-8), Chinchalli (SB-9), Prakash palya (SB-10), Naripura (SB-11), Adugulpodu (SB-12), Ramayanadoddi (SB-13), Jodukara hatti (SB-14), Depudisahibradoddi (SB-15) which range in area from 16.87 to 180.02 sq km. Different morphometric parameters were evaluated to understand the drainage characteristics. The drainage pattern of these sub basins have been delineated using Geocoded FCC bands 2, 3 and 4, of IRS 1C and 1D (LISS 111+ PAN merged) on 1:50,000 scale and Survey of India Toposheets as reference. The morphometric parameters are computed using Arc Info and Arc View GIS software’s. The drainage pattern of the study has shown dendritic to sub-dendritic drainage pattern with stream orders ranging from 4th to 5th order. The Drainage density ranges from 1.51 to 4.83 km/km 2 suggesting coarse to moderate drainage texture. The change in values of stream length ratio indicates their late youth stage of geomorphic development. The values of bifurcation ratio are ranging from 0.11 to 20.75 indicating that the study area is having strong structural control over the drainage pattern and all the sub basins fall under normal basin category. The values of form factor and circulatory ratio, suggest that the sub basins are elongated to circular in shape. Geographic Information System, when used with satellite images, could help in determining the morphometric parameters of watershed and river basins. It is concluded that remote sensing ground and GIS have been proved to be efficient tools in drainage delineation and updation.

NEW FINDINGS ON RIVER NETWORK ORGANIZATION: LAW OF EIGENAREA AND RELATIONSHIPS AMONG HORTONIAN SCALING RATIOS

Horton’s laws have long served as fundamental principles for fractal organization of a drainage basin. Scaling ratios of stream number, length, area, and side tributary have been proposed but the definitions of these basic variables are inconsistent. The concept of eigenarea can be utilized to resolve this issue. Here, we investigated the relationships among Hortonian scaling ratios using the concept of eigenarea. We found that the eigenarea ratio, likewise other scaling ratios, is invariant within a stream network, the law of eigenarea. We analytically revealed that the eigenarea ratio is equivalent to the stream length ratio. Our examination implies that Horton’s original two ratios of stream number and length can represent most Hortonian scaling ratios except Tokunaga ratio.

A study of morphometric evaluation of the Son basin, India using geospatial approach

This study deals that morphometric evaluation is feasible method of characterization of hydrological response behavior of the any river basin. In this study, Son basin a tributary of the Ganga river has been selected for the detailed morphometric evaluation. The Son basin is approximate 68,863km2 and shows sub-dendritic to dendritic drainage pattern. The measurement and analysis for Son basin and its five major sub-watershed are carried on GIS platform to describe the topography and drainage characteristics. The input parameters required to run this model are: a pour point, a minimum upstream area in sqkm and a digital elevation model. Streams were automatically extracted from ASTER DEM data. The stream order of the basin is predominantly controlled by physiographic and structural conditions. The study area is designated as sixth-order basin and lower order streams mostly dominate the basin with the drainage density value of 0.26km/km2. The slope of basin varied from 0° to 70.4° and the slope variation is mainly controlled by the local geology and erosion cycles. The bifurcation ratio (Rb) for the Son basin varies from 2.41 to 7. The higher values of Rb in basin indicate a strong structural and geological control on the drainage pattern. The elongation ratio of the basin is 0.553 indicating that the study area is extended with moderate to steep slopes. The increase in stream length ratio from lower to higher order shows that the basin is part of a mature geomorphic stage.

Evaluating the impact of lower resolutions of digital elevation model on rainfall-runoff modeling for ungauged catchments.

Geomorphological instantaneous unit hydrograph (GIUH) usually uses geomorphologic parameters of catchment estimated from digital elevation model (DEM) for rainfall-runoff modeling of ungauged watersheds with limited data. Higher resolutions (e.g., 5 or 10m) of DEM play an important role in the accuracy of rainfall-runoff models; however, such resolutions are expansive to obtain and require much greater efforts and time for preparation of inputs. In this research, a modeling framework is developed to evaluate the impact of lower resolutions (i.e., 30 and 90m) of DEM on the accuracy of Clark GIUH model. Observed rainfall-runoff data of a 202-km2 catchment in a semiarid region was used to develop direct runoff hydrographs for nine rainfall events. Geographical information system was used to process both the DEMs. Model accuracy and errors were estimated by comparing the model results with the observed data. The study found (i) high model efficiencies greater than 90% for both the resolutions, and (ii) that the efficiency of Clark GIUH model does not significantly increase by enhancing the resolution of the DEM from 90 to 30m. Thus, it is feasible to use lower resolutions (i.e., 90m) of DEM in the estimation of peak runoff in ungauged catchments with relatively less efforts. Through sensitivity analysis (Monte Carlo simulations), the kinematic wave parameter and stream length ratio are found to be the most significant parameters in velocity and peak flow estimations, respectively; thus, they need to be carefully estimated for calculation of direct runoff in ungauged watersheds using Clark GIUH model.

Morphometric Analysis of Diyung Watershed in Northeast India using GIS Technique for Flood Management

Abstract: The North eastern region is characterized by undulating terrain and high rainfall. Such condition creates a situation of floods in the downstream plain areas of Assam. Difficulties in monitoring the data collection of hydrological events (runoff and sediment yield) in the rugged terrain hinders the planning of suitable control measures. To overcome such constraints alternate measures need to be explored and the study of terrain is one such approach. The study of terrain (morphometry) can help in diagnosing the hydrological behavior of any watershed. In the present study morphometric analysis was done to determine the drainage characteristics of Diyung watershed in Kopili river basin using topographic maps and GIS tools. The morphometric analysis indicates high values of stream density (15464), stream length ratio (1.81); Bifurcation ratio (3.66), RHO coefficient (0.49), Stream frequency (5.26 km−2), Drainage density (3.24), indicative of high runoff generation capabilities of the watershed. This high runoff from the watershed is the main reason for floods in the downstream areas. Based on the results, structural and non-structural measures are proposed to mitigate the impacts of flood events.