Order Sub-basins Research Articles

Morfometría de una cuenca de los Andes Centrales, San Juan, Argentina: evaluación de los factores condicionantes del terreno a la ocurrencia de aluviones

The present work aims to determine flash flood occurrence prone areas, in the Jáchal river basin, San Juan Province, Argentina. The Jáchal river basin covers ~29,000 km2 and has a perimeter of ~2,400 km, while the eponymous river extends for nearly 570 km. It is a 7th order basin according to Strahler’s classification, subdivided into four 6th order sub-basins. Various morphometric basin characteristics are analysed and some basic and derived parameters are calculated. These calculations allow predicting the basin behaviour due to heavy rainfall, which translates into large volumes of water with peak flows capable of generating significant flash floods. The basin has a torrential character, so in case of intense rainfall the terrain conditions would contribute to increasing the flow of the main rivers. An inventory of alluvial deposits was carried out and their relationship with the conditioning variables of the terrain was evaluated. At the confluence zones, the river tributaries show more intense overflows than the main collector. This promotes the generation of flash floods. The areas most likely to be affected by flash flood events correspond to low-humidity, east-facing slightly rough terrains, with slopes of up to 15° as well as low-lying flood plain sectors, and at the confluence of tributaries with the main rivers. Populated centres and provincial and national routes are prone to be affected by alluvial events in the study area.

Implications of geomorphometric parameters on the occurrence of landslides in the Kali Valley, Kumaun Himalaya, India

The Kumaun Himalaya registers frequent seismicity, neotectonic behaviour and incessant rainfall which accelerate hillslope processes governing landsliding phenomenon. Within the Kali Basin between Jauljibi and Garbyang, morphometric analysis of 45 fourth order sub-basins were carried out to prepare an erosion potential map of the region. The spatial distribution of 376 landslides including 158 debris slide and 97 rockfalls correlates well with the erosion map depicting 40% landslides in very high zone, 15% in high zone, 33% in moderate zone, 12% in low zone across the Kali Basin. The dominant parameters responsible for the erosion were evaluated using statistical methods such as Principal Component Analysis (PCA) and Agglomerative Hierarchal clustering (AHC). The comparison of PC1, PC2 and PC3 illustrates high erosion activity around the Main Central Thrust (MCT) and within the Vaikrita and Chipplakote formations which strongly reflect the function of basin dimension, bifurcation ratio, drainage density, relief and shape parameters for sub-basins exhibiting high proneness to flooding and typical surface runoff. The PCA results are consistent with AHC, where AHC clusters correspond with PCA factor loadings. Morphotectonic analysis using steepness index (Ksn) and valley floor width to height ratio (Vf) for the Kali and Dhauli rivers were integrated with landslide inventory that indicate the highest landslide density across the active Seraghat-Tintola Fault (STF) near Tawaghat and moderate to high density near topographic fronts of closely spaced active Lasku Fault (LF), Ghatibagar Kalika Fault (GKF) Rauntis Fault (RF) that outcrop within the Lesser Himalayan Sequences(LHS) exposed between Dharchula and Jauljibi.The study provides an understanding of quantitative geomorphometry as an useful approach to identify potentially active zones for slope failures and provide a guide to decision-makers in regional planning and mitigating the landslide hazard in the Kali valley which is developing hub for large scale infrastructural and tourist activities.

Структурно-морфометрический анализ малого речного бассейна реки Ихе-Ухгунь (бассейн реки Иркут)

The article is devoted to the structural and morphometric analysis of a small rivers using the example of the Ihe-Ukhgun river basin (left tributary of the Irkut river), which is based on a complex processing of a digital elevation model (DEM). The author has prepared a hydrologically correct DEM based on the ALOS Digital Surface Model (DSM) satellite data, carried out an automated calculation and mapping of the basin erosion network based on the DEM data, calculated the structural indicators of the third-order basins for analyzing the basin organization of the small rivers network. Structural and morphometric analysis using GIS was practically not used for the Ihe-Ukhgun river basin which is placed in different landscapes, geological and geomorphological conditions. The work is based on geomorphometric and structural morphometric methods as well as the method of geoinformation mapping and relief modeling for analyzing lower-order basins. Thalweg erosion network modeling up to the fourth order of the river basin Ihe-Uhgun was carried out with using of DEM analysis in the ArcGIS 10 program. The map of the erosional network of the basin was constructed, morphometric indicators of rivers (length, area of basins, sum of slopes, coefficient of basin asymmetry, etc.) were obtained, and then the indices of the basin structure (structure of bifurcation, lengths, areas and slopes) were calculated. As a result, an asymmetric erosion network was revealed, which indicates a great work in the transfer of matter of first-order streams. First-order streams exceed those of the second and third orders streams in terms of catchment area, length and steepness of adjacent slopes. The interrelation of morphometric characteristics of different-order streams within third order sub-basins are most fully traced with the using of structural indices and their comparison with modal indicators. In general, the Ihe-Ukhgun river basin is characterized by a heterogeneous structure of the streams ratio of the first, second and third orders. The basins of the Khurguta, Khubyty and Ulan-Gol rivers have the highest degree of homogeneity. At the same time, for the Ihe-Ukhgun river basin, there is no direct relationship with the area of the third order drainage basins.

Catchment scale simulations of soil moisture dynamics using an equivalent cross-section based hydrological modelling approach

Physically based distributed hydrological models are useful for simulating the spatial distribution of hydrologic fluxes across the catchment under various climate and land cover change scenarios. However, complexities associated with their implementation at large scales make their applications limited. Previously, an equivalent cross-section (ECS) based distributed hydrological modelling approach was developed for first order sub-basins to reduce the computational time/effort. Here, the ECS approach is modified for semi-distributed hydrological modelling at the catchment scale. The modelling approach is implemented for a 314 km2 McLaughlin catchment located in south-eastern New South Wales (NSW), Australia that consists of 822 first order sub-basins. A 26 year long streamflow record simulated using an ECS based modelling approach are compared against daily observed streamflow and four calibrated lumped conceptual hydrologic models, and found to be consistent. Further, the simulated actual evapotranspiration and soil moisture from the ECS approach are compared against the Australian Water Availability Project (AWAP) model simulations and results found to be consistent. In addition, the temporal dynamics of simulated soil moisture from the ECS approach is consistent with the satellite derived European Space Agency Climate Change Initiative (ESA CCI) surface soil moisture data. In the ECS based semi-distributed modelling, all parameters are derived from the actual topographic and physiographic information of the catchment and none of the parameters is calibrated. Therefore, this approach has the advantage of simulating streamflow in ungauged catchments compared to lumped conceptual models. The impact of spatially distributed climatic forcing and land cover on soil moisture is investigated across four landforms (upslope, midslope, footslope and alluvial-flats) and at various soil depths. Our results show increase of mean soil moisture in shallow layers of upslope toward alluvial-flats. However, mean soil moisture in deeper horizons remained almost constant across all landforms. The variability of daily soil moisture at surface soil layers is higher than the deeper soil layers for all landforms. Our results illustrated that disaggregation of a catchment to a series of ECS at the scale of first order sub-basins, captures dynamics of soil moisture and actual evapotranspiration across the landscape and results are consistent with the climatology, land cover type, topography and soil hydraulic properties. Further, the use of ECS approach in the McLaughlin catchment reduced the number of computational units by 40 times in comparison to 3-d grid based distributed modelling setup.

Application of remote sensing and GIS for identification of potential ground water recharge sites in Semi-arid regions of Hard-rock terrain, in north Karnataka, South India

Hydro-geomorphological characteristics, together with soil, slope, lineament density and Land use Land cover are signatures of potential ground water recharge areas, and are vital for water harvesting. In the present paper, Fifth order sub-basins in Semi-arid regions of the Varada River basin in South India is studied for selection of suitable area for recharge and prioritize the sub-basins using Indian Remote Sensing satellite (IRS) P6; Linear Imaging Self Scanning Sensor (LISS III) and ArcGIS 9.2. The Fifth order sub-basins of the Varada River spread in Hard-rock terrain and of different agro-climatic zones. The study shows that there are significant spatial variations in the fifth order basins with respect to their morphometric characteristics such as the basin area, drainage density, bifurcation ratio, and circularity ratio, constant of channel maintenance and slope of the basin. These variations reflect the differences in the hydrological process in the different Sub-basins. Based on the variations in the linear, aerial, relief as well as the slope, lineament density, and precipitation pattern rankings are assigned for each parameter with respect to ground water recharge within the Subbasins. Weighted sum overlay for precipitation, Land use, soil and Water table fluctuation are used to select the suitable areas of recharge within the sub-basins. Buffers created for lineaments and drainage networks were intersected with the suitable area of recharge for the probable tank's locations for recharge. The tank locations identified after intersection and having higher stream orders are further filtered for the identification of potential sites for ground water recharge. In the prioritized sub-basins SB-8, SB-10, SB-11 locations have been selected for recharge.

Assessment of soil erosion in a tropical mountain river basin of the southern Western Ghats, India using RUSLE and GIS

Revised Universal Soil Loss Equation (RUSLE) model coupled with transport limited sediment delivery (TLSD) function was used to predict the longtime average annual soil loss, and to identify the critical erosion-/deposition-prone areas in a tropical mountain river basin, viz., Muthirapuzha River Basin (MRB; area = 271.75 km2), in the southern Western Ghats, India. Mean gross soil erosion in MRB is 14.36 t ha−1 yr−1, whereas mean net soil erosion (i.e., gross erosion–deposition) is only 3.60 t ha−1 yr−1 (i.e., roughly 25% of the gross erosion). Majority of the basin area (∼86%) experiences only slight erosion (<5 t ha−1 yr−1), and nearly 3% of the area functions as depositional environment for the eroded sediments (e.g., the terraces of stream reaches, the gentle plains as well as the foot slopes of the plateau scarps and the terrain with concordant summits). Although mean gross soil erosion rates in the natural vegetation belts are relatively higher, compared to agriculture, settlement/built-up areas and tea plantation, the sediment transport efficiency in agricultural areas and tea plantation is significantly high, reflecting the role of human activities on accelerated soil erosion. In MRB, on a mean basis, 0.42 t of soil organic carbon (SOC) content is being eroded per hectare annually, and SOC loss from the 4th order sub-basins shows considerable differences, mainly due to the spatial variability in the gross soil erosion rates among the sub-basins. The quantitative results, on soil erosion and deposition, modelled using RUSLE and TLSD, are expected to be beneficial while formulating comprehensive land management strategies for reducing the extent of soil degradation in tropical mountain river basins.

Morphometric Analysis of Gilgit River Basin in Mountainous Region of Gilgit-Baltistan Province, Northern Pakistan

Watershed morphometric analysis of a basin is key to understand the hydrological processes. The Gilgit river basin is situated in the Hindu Kush and Karakoram Mountains of Pakistan. The provincial capital of Gilgit-Baltistan is located in the lower part of the basin. Morphometric evaluation of the Gilgit river basin was carried out to study its drainage characteristics and overall water resource potential. The entire Gilgit river basin has been divided into six sub-basins to calculate and analyze the selected morphometric parameters. Morphometric parameters have been classified into linear, aerial and relief aspect. Geographic Information System (GIS) provides a viable method to extract and evaluate the characteristic of hydrological response behaviour of the basin. In the present study the utilization of remote sensing data such as Thermal Topography Mission and Global Elevation Model (ASTER-GDEM), Sentinel 2A image, coupled with geological and field data into GIS environment for morphometric analysis of Gilgit Basin. The drainage area of the basin is 13,538 km2 and shows a dendritic drainage pattern for all sub-basins. The analysis reveals that drainage network of entire Gilgit river basin constitutes a 7th order basin. Out of six sub-basins, Gilgit-Gahkuch (B1), Ishkoman (B2) and Phunder (B4) are 6th order sub-basins. Yasin (B3) and Gupis (B5) are 5th order sub-basins, while Bagrot (B6) is a 4th order sub-basin. The Gilgit Basin drainage density value is 0.50 km/km2, which indicates a well-drained basin. Morphometric parameters like stream number, order, length, bifurcation ratio, drainage density, stream frequency, elongation ratio, circularity ratio, form factor, relief and relative relief, slope, length of overland flow, ruggedness number, and hypsometric integral are calculated. The results indicate that the entire drainage basin area reflects youthful to early mature stage of the fluvial geomorphic cycle and high potential of stream discharge which is dominated by high relief, rainfall, glacier and snow fed order streams.

Assessing the impact of arid area urbanization on flash floods using GIS, remote sensing, and HEC-HMS rainfall–runoff modeling

This study uses an integrated approach, bringing together geographic information system (GIS), remote sensing, and rainfall–runoff modeling, to assess the urbanization impact on flash floods in arid areas. Runoff modeling was carried out as a function of the catchment characteristics and the maximum daily rainfall parameters. Land-use types were extracted from the supervised classification of SPOT-5 (2010) and Landsat-8 (2015) satellite images and were validated during field checks. Catchment morphometric characteristics were carried out using the correlated Topaz and Arc-Hydro tools. Maximum floods of the catchment were evaluated by coupling GIS and remote sensing with Hydrologic Engineering Center–Hydrologic Modeling System (HEC-HMS) hydrologic modeling. Peak discharges were estimated, and the abstraction losses were computed for different return periods. The model results were calibrated according to actual runoff event. The research shows that rapid urbanization adversely affects hydrological processes, since the sprawl on the alluvial channels is significant. This reduces infiltration into the underlying alluvium and increases runoff, leading to higher flood peaks and volumes even for short duration low intensity rainfall. To retain a considerable amount of water and sediments in these arid areas, construction of small dams at the fingertip channels at the outlet of the lower order sub-basins is recommended.

Hypsometric Analysis of Wadi Mujib-Wala Watershed (Southern Jordan) Using Remote Sensing and GIS Techniques

Hypsometric analysis is considered an effective tool for understanding the stages of geomorphic evolution and geological development of river catchment, and for the delineation of erosional proneness of watershed. In the present study, twenty eight fourth order sub-basins of W. Mujib-Wala (Southern Jordan) were selected, and hypsometric analysis was carried out using 30 m ASTER DEM. Elevation-relief ratio method was employed to calculate the hypsometric integral values within GIS environment. The hypsometric integral values range from 0.71 to 0.88, whereas, the hypsometric curves exhibit remarkably upward convex shapes which indicate that all sub-basins and the W. Mujib-Wala watershed are at the youth-age stage of geomorphic development. Thus, they are of high susceptibility to erosion, incised channel erosion and mass movement activity. Marginal differences exist in mass removal from the watershed and the 28 sub-basins are attributed to variation in tectonic effect, lithology and rejuvenation processes. The relation between basin area and hypsometric integral was examined using regression analysis. Results reveal that negative and weak relationships dominate, where r2 ranges from 0.05 to 0.478 which confirm with other results reported elsewhere. Indirect assessment of erosion status based on hypsometric integral values was validated using estimated sediment yield information related to wadi Mujib and wadi Wala watersheds separately. The recorded sediment yields were in affirmation with high hypsometric integrals values, where higher values of hypsometric integrals and sediment yields occurred in the western part of the W. Mujib-Wala watershed. These findings would help in the construction of appropriate soil and water conservation measures across the watershed and its sub-basins to control soil erosion, to conserve water, and to reduce sediment discharge into the W. Mujib and W. Wala reservoirs.

Morphometric analysis of Suketi river basin, Himachal Himalaya, India

Suketi river basin is located in the Mandi district of Himachal Pradesh, India. It encompasses a central inter-montane valley and surrounding mountainous terrain in the Lower Himachal Himalaya. Morphometric analysis of the Suketi river basin was carried out to study its drainage characteristics and overall groundwater resource potential. The entire Suketi river basin has been divided into five sub-basins based on the catchment areas of Suketi trunk stream and its major tributaries. Quantitative assessment of each sub-basin was carried out for its linear, areal, and relief aspects. The analysis reveals that the drainage network of the entire Suketi river basin constitutes a 7th order basin. Out of five sub-basins, Kansa khad sub-basin (KKSB), Gangli khad sub-basin (GKSB) and Ratti khad sub-basin (RKSB) are 5th order sub-basins. The Dadour khad sub-basin (DKSB) is 6th order sub-basin, while Suketi trunk stream sub-basin (STSSB) is a 7th order sub-basin. The entire drainage basin area reflects late youth to early mature stage of development of the fluvial geomorphic cycle, which is dominated by rain and snow fed lower order streams. It has low stream frequency (Fs) and moderate drainage density (Dd) of 2.69 km/km 2. Bifurcation ratios (Rb) of various stream orders indicate that streams up to 3rd order are surging through highly dissected mountainous terrain, which facilitates high overland flow and less recharge into the sub-surface resulting in low groundwater potential in the zones of 1st, 2nd, and 3rd order streams of the Suketi river basin. The circulatory ratio (Rc) of 0.65 and elongation ratio (Re) of 0.80 show elongated nature of the Suketi river basin, while infiltration number (If) of 10.66 indicates dominance of relief features and low groundwater potential in the high altitude mountainous terrain. The asymmetry factor (Af) of Suketi river basin indicates that the palaeo-tectonic tilting, at drainage basin scale, was towards the downstream right side of the drainage basin. The slope map of Suketi river basin has been classified into three main zones, which delineate the runoff zone in the mountains, recharge zone in the transition zone between mountains and valley plane, and discharge zone in the plane areas of Balh valley.

DEM resolution and stream delineation threshold effects on the results of geomorphologic-based rainfall runoff models

Digital elevation model (DEM) resolution and the assigned threshold for river network delineation aect the results of rainfall-runo models. In this study, the eects of these 2 issues on the extracted geomorphologic parameters of watersheds and the performance of a kinematic wave based model, called KW-GIUH, are investigated. The results show that by decreasing the DEM resolution at xed thresholds, parameters such as subbasin mean slope and the number of streams decrease and the area of the ith order subbasins and the mean length of the overland ow increase. Moreover, the results indicate that the reduction of the DEM resolution at a xed threshold causes the peak ow and hydrograph time base to decrease up to the cell size of 100 m and then, after experiencing a jump, again decrease with the increase of the cell size. According to the achieved results, above the threshold of 2%, the dierence between the peak ows of dierent hydrographs at dierent resolutions is meaningful. The KW-GIUH sensitivity to DEM resolutions and thresholds is sharper in peak ow and then in hydrograph time base and time to peak. At a xed threshold, the value of time to peak

Investigation of scale dependence and geomorphic stages of evolution through hypsometric analysis: a case study of Sirsa basin, western Himalaya, India

Hypsometric analysis is an important tool to identify and justify the erosional status, erosional processes, geologic and tectonic influences, and stage of landscape development of a basin. In this study, scale dependence of hypsometric integral (Ea) and hypsometric curve parameters were derived and analysed for various order sub-basins of Sirsa river. Here, Ea of higher order sub-basins are quite scale dependent and controlled by lithology; albeit Ea of all order sub-basins is independent of tectonic uplift. Based on Ea, all fourth and fifth order sub-basins were categorised in three classes. The analysis of hypsometric curve parameters showed that sub-basins of first category (Ea < 0.35) is characterised by upward-concave curve, fluvial process dominated and early old stage landscape. Sub-basins of second category (0.35 < Ea < 0.45) reflects concave-convex curve, dominance of fluvial process and mature landscape; whereas third category sub-basins (Ea > 0.45) are diffusive process dominated and belong to late youth to early mature stage.

Drainage Basin Delineation and Quantitative Analysis of Panamaram Watershed of Kabani River Basin, Kerala Using Remote Sensing and GIS

Abstract The morphometric analysis was carried out to determine the drainage characteristics of Panamaram watershed (PW) of Kabani river basin, Kerala, India with emphasis on fourth order sub-basins (FOSBs) using Geocoded imageries of IRS-IC LISS III FCCs (1997) of 1:50,000 scale, aerial photographs (1990) of 1:15,000 scale and Survey of India toposheets (1968) on 1: 50,000 scale. The main idea was to examine the stream properties based on the measurement of various stream attributes. The different drainage parameters studied and the measurements related to perimeter, area of sub-basins, basin length and number of rivers were determined by using Map Info 6.5 techniques. The drainage pattern of the PW is dendritic, a sixth order stream. There are 587, 135, 36 and 12 first, second, third and fourth order Hortonian streams, respectively in PW. The mean bifurcation ratio indicates that the drainage pattern is not much influenced by geological structures. The shape parameters reveal the elongation of the basin and sub-basins. The applicability of Horton’s Laws on Stream numbers, Stream lengths and Stream areas is tested by using the theory of regression by estimating theoretically bifurcation ratio, length ratio and area ratio. For the fourth order sub-basins of 1, 2, 4, 5 and 8 of PW, a second degree polynomial equation seems to be a better model than the Hortonian model.

Summer drought disturbance on plant detritus decomposition processes in three River Tirso (Sardinia, Italy) sub-basins

Here, we study the variation patterns of detritus decomposition along a river continuum in a Mediterranean type river basin, and the influence of summer drought disturbance on this pattern. The study was carried out in three 4th order sub-basins (hereafter referred to as Assolo, Laconi and Olzai) of the river Tirso basin (Sardinia, ITALY), with one study site per stream order in each sub-basin (4 stream orders × 3 sub-basins = 12 study sites). The three sub-basins were selected according to their exposure to summer drought, Assolo being the most exposed and Laconi the least exposed. Reed (Phragmites australis (Cav.) Steudel) detritus decomposition was studied during the fall and spring periods, utilising the leaf packs technique with 3 sampling dates and 8 replicate packs per sample in each period. At all sites, the stream width was recorded fortnightly for one year. Overall, the reed leaf packs underwent rapid decomposition in the river Tirso basin (k=0.0193 d−1), but very high variation was observed among leaf pack decomposition rates (C.V. = 112.7%). Seasons, sub-basins, and stream orders accounted for 88% of the total variance observed (Three Way ANOVA). The decomposition rate was significantly higher in spring than in fall, in the Laconi sub-basin than in the Olzai and Assolo sub-basins, and in 4th order streams than in 2nd and 3rd. Decomposition rates were also higher at relatively undisturbed sites than at the study sites exposed to complete summer desiccation (e.g., 2nd, 3rd, 4th in the Olzai sub-basin; 1st, 2nd, 3rd in the Assolo sub-basin). The strongest effects of summer drought disturbance occurred at the lowest order stream branches (i.e., 1st and 2nd order) suggesting that the resilience of detritus decomposition processes to the disturbance arising from Mediterranean type climates increases with stream order.