SCS-CN Model Research Articles

Calculating Surface Runoff by Scs-Cn Model in the Sanjai River Basin, Jharkhand

Surface runoff prediction is a very intricate, evolving, and exponential phenomenon controlled by numerous interconnected components. Regulated by numerous types of related factors, surface runoff production is a highly complex, dynamic, and non-linear phenomena. Advancement and long-term control of water resources depend on run-off forecast. For runoff forecasts, many techniques and models are at hand; Among strategies, “Soil Conservation Services curve number(SCS- CN)” approach stands out. In order to determine potential outflow from a drainage system or region, the SCS implemented the Curve Number index. It is possible to figure out the curve number of a drainage basin by taking into account the antecedent moisture conditions(AMC), the soil, land surface use and land cover (LULC). Considered also is the Hydrological Soil Group (HSG). Four kinds of soils are offered at HSG: “A, B, C, and D”. Whereas soil type D stands for low penetration rates and greater surface flow capacity, soil category A comprises higher penetration rates below the surface and less runoff potentiality. The study's research site was the Sanjai river basin in Jharkhand. Arc Gis 10.1 and Erdas 14 software helped produce thematic layers like soil maps, LULC maps, and so on. The whole catchment was divided into sub-watersheds in order to more accurately measure runoff. The findings demonstrate that the SCS-CN simulation performs productive runoff estimates. The research demonstrates that more sustainable water use results from suitable surface runoff analysis.

Relative prioritizing of sub-watersheds of Barak River built on, morphometric parameters, LULC and SCS-CN model

Relative prioritizing of sub-watersheds of Barak River built on, morphometric parameters, LULC and SCS-CN model

Urbanization enhances channel and surface runoff: A quantitative analysis using both physical and empirical models over the Yangtze River basin

Urbanization has become an irreversible trend and is even more rapid in flood-prone area. However, the responses of both channel runoff and surface runoff to the urbanization and the underlying mechanisms still deserve more in-depth exploration within urban extents with limited data availability. Accordingly, we conducted a comprehensive quantitative analysis of the urbanization effects on channel and surface runoff from both statistical and model-based perspectives over three major urban agglomerations (i.e., Chengyu (CY), middle region of Yangtze River (MRYR), Yangtze River Delta (YRD)) in the Yangtze River Basin. The long-term high-resolution channel and surface runoff under different urbanization scenarios were simulated using both WRF-Hydro and SCS-CN models by integrating multiple remotely sensed, reanalysis, and in-situ datasets. Results demonstrated that the channel runoff increased by 4.4%, 5%, and 12.08% in CY, MRYR, and YRD urban agglomerations, respectively. Meanwhile, the urbanization also contributed to 30%, 21.4%, and 17.7% of the surface runoff changes in three urban agglomerations. Based on the high-resolution local climate zone (LCZ), our results highlighted that the high-rise and middle-rise buildings and compact-arranged regions were more prone to accumulating surface runoff and trigger flooding events due to the weaker infiltration capacity of land surface with the densely distribution of impervious surface. Further machine learning based investigation and case analysis also explored the potential influencing factors and mechanisms of the impact of urbanization on channel and surface runoff. Results in the current research show further evidence that policy makers of urban planning and management need to consider and ensure societal preparedness for extreme runoff and flooding events.

Assessing the impact of land use and land cover (LULC) changes on the surface runoff downstream of an ungauged Bontanga watershed in Northern Ghana

Abstract Anthropogenic activities exacerbated by population growth, demanding land for food production and settlements, have led degradation of the Bontanga watershed. The aim of this study was to assess the impact of land use and land cover (LULC) change on the surface runoff in the Bontanga watershed from 1997 to 2022. LULC change maps for the years 1997, 2002, 2013, and 2022 were generated from Landsat images using ArcGIS, achieving overall accuracies of 92, 91.89, 95.27, and 83.64%, respectively. Surface runoff was estimated using the SCS–CN model. Correlation analysis was employed to identify predominant LULC change classes that impact surface runoff. The agricultural land and built-up area increased by 20.81% and 27.20% causing an increase in the surface runoff by 13.92 and 14.49% from 1997 to 2022. Due to anthropogenic activities, dense forest, grassland, mixed forest and shrub land, mixed shrub and grassland decreased by 20.31, 29.97, 22.51, and 25.58% causing an increase in surface runoff by 14.98, 14.06, 15.78, and 15.05%, respectively. Correlation analysis showed that changes in surface runoff were positively correlated with agricultural land, and mixed forest and shrub and negatively correlated with mixed shrub and grassland, and grassland.

Rainfall trend analysis to the change of flood discharge estimation in Bengawan Solo River

Bengawan Solo Watershed is the largest watershed on Java Island, which also has fluctuating rainfall. The fluctuating rainfall may cause an alteration to the river discharge. The alteration can be analyzed through the SCS-CN model and Synder Unit Hydrograph. SCS-CN Java Island, which also has fluctuating rainfalis a well-known model in hydrological modeling that is commonly used because of its simplicity, stability, and predictability. Synder Unit Hydrograph is suitable for ungauged basins and may be used in watersheds about 25 km2 to 25.000 km2 (Sudhakar BS et al, 2015). The analysis and calibration were performed from the baseline data (2001-2022). The trend analysis was carried out by comparing the analysis results from data sequences with a ten-year range with the baseline data. According to the trend analysis, the rainfall design of the Bengawan Solo watershed has increased by approximately 4–6% in 2013–2022 compared to the baseline (2001-2022), which may lead to a 10% increase in flood design discharge in Bengawan Solo.

Estimating the surface runoff volume of Wadi Al-Ziyadi basin using the SCS-CN model in northeastern Wasit Governorate

Estimating the surface runoff volume of Wadi Al-Ziyadi basin using the SCS-CN model in northeastern Wasit Governorate

Changes in the Active Drainage Network and Their Impact on the Hydrological Response and Flood Risk Management Process: A Case Study for a Flysch Mountain Catchment

The active drainage network (ADN), as a dynamic component of a catchment, plays an important role in a catchment’s functioning. Changes in the ADN are the most noticeable during extreme hydro-meteorological events, and they result from, among others, the incorporation of man-origin incisions into the ADN. Knowledge of the parameters of the “real” ADN is a key element in the field of catchment hydrology because the ADN affects the intensity of hydro-, geomorpho-, and biological processes. The goals of this study are to assess (1) the changes in the ADN during extreme hydro-meteorological events (with special attention paid to the human-induced impact on the ADN transformation) and (2) the consequences of the ADN changes on the hydrological response of a catchment and their impact on the flood hazard/risk management processes. The study was performed in a mountain catchment, prone to flash flood occurrences. The ADN was reconstructed with the use of ALS-LiDAR data using GIS tools, and the hydrological response was evaluated by using SCS-CN and GIUH models. The results revealed that the ADN functioning during heavy rainfalls is three to four times denser than the natural-origin river drainage network (RDN) (11.4 km·km−2 vs. 2.9 km·km−2), and the RDN is significantly modified by human-origin elements (e.g., roads, ditches, furrows, etc.—they constitute ca. 1/3 of the ADN). Moreover, significant structural changes in the ADN have occurred, which were confirmed by the Hortonians’ type of analysis. The changes in the ADN have affected the hydrological response of the catchment (predominantly an increase in the peak flow—up to 7%) and the dimensions of the 1% probable flood hazard zone (increase of ca. 5%). It may be concluded that significant changes in the ADN, in the catchment studied, had a moderate impact on the changes in the flood hazard level. The results give a new insight into the flood hazard/risk assessment processes in a small flysch mountain catchment.

Research on rainfall prediction based on RBF neural network model and stormwater inundation risk in scenic areas: A case study of the Yesanpo Scenic Area, Baoding, China

Research on stormwater inundation risk and rainwater management in scenic areas has a lot to do with rainfall during the flood season. When the measured rainfall data is limited, an artificial network model with nonlinear mapping capability can be applied to predict rainfall data during the flood season, which increases the sample size of rainfall data and improves the accuracy of research results. Based on a radial basis function (RBF)neural network model, this paper takes the Yesanpo Scenic Area in Baoding City, Hebei Province as an example to estimate the monthly maximum rainfall data during the flood season (July–September) of 2022, 2023, and 2024 in the study area. On this basis, the Pearson III frequency curve is used to calculate the design rainfall corresponding to the rainfall frequency of 20%, 5%, and 2%. With the help of SCS-CN model and ArcGIS spatial analysis tools, the stormwater inundation areas are simulated in the study area, which are divided into three risk levels: high, medium, and low, providing a reference for the stormwater management in the Yesanpo Scenic Area.

Estimation of the runoff of the Qalatopzan and Parewla Basins using the (SCS-CN) model

In this study, water runoff estimation by SCS-CN model for both Qalatopzan and Parewla watersheds which located in northeastern of Iraq and eastern part of Kurdistan Region in Kalar district, and lies on latitude (34o:51-: 33=) and (35o :04-: 52=) north and longitude (45o:21-: 50=) and(45o :34-: 59=) east thet located in the semi-mountainous area. The total catchment area is about (235.46 km2), and Qalatopzan watershed with an area of ​​(148.74 km2) with a rate of (63.17%) and Parewla drainage with an area of ​​(86.72 km2) and (36.83%) form the research area which distributed into two main streams and (8) Sub-watersheds, each of which includes four minor sub-watersheds. Rainfall irregularities accompanied by environmental and climatic effects have created water shortage problems for the study area, especially during the dry seasons, and in order to achieve the research objective which is to determine the amount of water flowing and appoint the level of utilization of hydrology of both watersheds, each of its files (DEM12.5m), aerial imagery (Landsat8 OLI), Geographic Information Systems and Remote Sensing (GIS & RS) techniques were used. After taking (10) soil samples and determining the numerical value of soil turbidity and humidity and the appearance of (7) different land uses and taking a wave of rainfall. The study concluded that the average depth of the runoff water in the study area is equal to (22.41 mm) which is (24.72 mm) in the main watershed of Qalatopzan and (20.11 mm) in the main watershed of Pariole, and the water flowing is about (2,60m3), while in the main reservoir of Qalatopzan (3.34m3) and in Parewla is (1.77m3). Finally, the results obtained are an important basis for the development of water harvesting and exploiting plans, so as to meet water needs and sustain human activities along the border of both brooks.

Presentation of a Rainfall–Runoff Retention Model (3RM) Based on Antecedent Effective Retention for Estimating Runoff in Seven Basins in Iran

This study aims to correct and assess the SCS-CN model. In this research, the 3RM model (written by Shamohammadi) has been modified in such a way that the maximum primary retention (I), maximum secondary retention (Fmax), and basin potential retention (Smax) can be calculated using precipitation (Pa). The purpose of this study is to evaluate the total retention model (St=f(Fmax,Smax,pa)) and the runoff model (Q=f(St,pa)) using the mountain basins of Iran, including Emameh, Kasilian, Navrood, Darjazin, Kardeh, Khanmirza, and Mashin. The results showed that the primary retention, maximum secondary retention, and retention capacity are, respectively, 2.3, 30.4, and 32.7 mm in Imamah, 2.5, 48.6, and 51.1 mm in Kasilian, 2.4, 26.7, and 29.1 mm in Navrood, 3.2, 21.5, and 24.7 mm in Darjazin, 1.7, 15.0, and 16.7 mm in Kardeh, 2.5, 33.2, and 38.1 mm in Khanmirza, and 4.9, 44.5, and 50.6 mm in Mashine. Additionally, the λ (ratio of primary retention to potential retention) values for all basins are less than 0.2 (suggested by SCS) and vary between 0.05 in Kasilian and 0.1 in the Darjazin, Kardeh, and Mashine basins. The results of fitting the model to the rainfall-runoff data showed that the evaluation indices, including the coefficient of determination (R2), Nash–Sutcliffe (NS), and root mean square error (RMSE), for predicting the runoff in the basins varied between 0.78 to 0.96, 0.78 to 0.961, and 0.86 to 2.28, respectively. According to the obtained results, it can be concluded that the model has an acceptable ability to predict runoff for all the studied basins.

A Study on the Accessibility of the Emergency Medical Services for Urban Kindergartens and Nursing Homes Based on Urban Pluvial Flooding Scenarios

Vulnerable groups such as children and the elderly are the focus of emergency medical rescue during urban pluvial floods. Taking the Erqi District of Zhengzhou City as an example, the SCS-CN model and Chicago rainfall model are used to simulate pluvial flooding based on the comprehensive consideration of urban rainfall, runoff, topography, and drainage. Additionally, the accessibility of emergency medical aid for kindergartens and nursing homes is evaluated in the Erqi District of Zhengzhou under different pluvial flooding scenarios using GIS network analysis technology. The results showed that the number of kindergartens and nursing homes without timely access to emergency medical rescue increased with the increase in precipitation return periods. Under the 500-year and 1000-year pluvial flooding scenarios, kindergartens and nursing homes that can obtain emergency medical rescue had delayed response times. Furthermore, with the increase in the precipitation return periods, both the number and delay time of kindergartens and nursing homes significantly increased. The accessibility and delay time of emergency medical rescue in kindergartens and nursing homes were determined by the intensity of pluvial flooding (including inundation area and depth), road traffic conditions, and the number and location of medical institutions, nursing homes, and kindergartens. The research results can provide a scientific basis for improving the refinement level of urban flood disaster management and emergency response services.

Evaluating the Effect of Deforestation on Decadal Runoffs in Malaysia Using the Revised Curve Number Rainfall Runoff Approach

This study presents a revised and calibrated Soil Conservation Service (SCS) curve number (CN) rainfall runoff model for predicting runoff in Malaysia using a new power correlation Ia = SL, where L represents the initial abstraction coefficient ratio. The traditional SCS-CN model with the proposed relation Ia = 0.2S is found to be unreliable, and the revised model exhibits improved accuracy. The study emphasizes the need to design flood control infrastructure based on the maximum estimated runoff amount to avoid underestimation of the runoff volume. If the flood control infrastructure is designed based on the optimum CN0.2 values, it could lead to an underestimation of the runoff volume of 50,100 m3 per 1 km2 catchment area in Malaysia. The forest areas reduced by 25% in Peninsular Malaysia from the 1970s to the 1990s and 9% in East Malaysia from the 1980s to the 2010s, which was accompanied by an increase in decadal runoff difference, with the most significant rises of 108% in Peninsular Malaysia from the 1970s to the 1990s and 32% in East Malaysia from the 1980s to the 2010s. This study recommends taking land use changes into account during flood prevention planning to effectively address flood issues. Overall, the findings of this study have significant implications for flood prevention and land use management in Malaysia. The revised model presents a viable alternative to the conventional SCS-CN model, with a focus on estimating the maximum runoff amount and accounting for land use alterations in flood prevention planning. This approach has the potential to enhance flood management in the region.

Sensitivity and performance evaluation of improved SCS-CN model by incorporating temporally decaying retention parameter with varying soil moisture for more versatile applications

Sensitivity and performance evaluation of improved SCS-CN model by incorporating temporally decaying retention parameter with varying soil moisture for more versatile applications

Runoff and Infiltration responses of revegetated slopes to clipping management on the northern Loess Plateau

Large-scale vegetation restoration can reduce local watershed water yield, limit vegetation establishment and subsequent growth, and influence regional ecosystem functions. Clipping management by reducing aboveground parts of grassland was gradually recommended and adopted in Grain-for-Green project management to offset these additional issues. Thus, scientific evaluation of the effectiveness of clipping management on infiltration and runoff processes is necessary for maintaining the stability of the surface water system and the sustainability of vegetation restoration in semi-arid regions. A field simulated rainfall experiment was conducted with four managed clipping grasslands (mainly bunge needlegrass and Stipa grandis), including no clipping, light clipping, heavy clipping, and complete clipping under three slope gradients (10, 20, and 30°) and three rainfall intensities (60, 90, and 120 mm/h) to explore the mechanism of runoff and infiltration responses to clipping using structural equation modeling and variation partitioning based on an SCS-CN model. The results showed the runoff coefficient of the light clipping, heavy clipping, and complete clipping plots were 1.33, 2.22, and 4.22 times that of the no clipping plot. The light clipping, heavy clipping, and complete clipping plots decreased the infiltration coefficients by 0%, 5%, and 26% relative to the no clipping plot. Rainfall intensity dominated runoff and infiltration amounts, and clipping intensity's total effect was stronger than slope gradient. Clipping intensity and slope gradient were more influential on runoff with increasing rainfall intensity. The mutual inhibition effect was between clipping intensity and slope gradient on runoff. In order to maintain the sustainability of restoration, a 25–50% vegetation coverage after clipping maximizes the benefits of increasing runoff and maintaining enough soil water supply that prevents possible soil drought. We propose that future vegetation restoration policies should evaluate the appropriate clipping intensity; meanwhile, local physiographic and climate conditions should be considered. These findings may offer guidance for the development of measures for runoff regulation and ecosystem functions of the watershed during vegetation restoration on the northern Loess Plateau.

LiDAR DTM Application for Flood Inundation Modeling and Visualization (Case Study: Batu City, East Java)

LiDAR DTM has been widely used for simulating flood inundation from river overflows. This flood inundation simulation needs to be done as an alternative step in the flood control system and flood disaster mitigation to determine the estimated area affected by the flood. Flood simulation is a form of unsteady flow that is simulated with the HEC-RAS program that allows the user to perform one-dimensional steady flow, one and two-dimensional unsteady flow calculations, sediment transport/mobile bed computations, and water temperature/water quality modeling, and visualizes flooded areas and flood-affected areas using a geographic information system approach. Hydrological data is obtained from daily rainfall processing at the time of station rain. Hydrograph analysis was performed using the SCS CN model on the HEC-HMS software to estimate the flow rate and peak discharge. Watershed area, curve number, Impervious value, Initial ion, and time lag are parameters that affect hydrograph analysis. From the results of the hydrograph analysis, the peak discharge of the model is 119.992 m2/s. Meanwhile, hydraulic analysis using HEC-RAS resulted in an inundation of 364 m2 which inundated three villages, namely Bulukerto, Bumiaji and Sidomulyo villages. The depth of the inundated area ranged from 0-15 m with an average depth of 4.534 m. The Sidomulyo area affected by the flood inundation scenario is 4,924 meters with an area of 0,02 ha. Bumiaji village was flooded with an area of 0,007 ha with a scenario of inundation depth of 4,049 m. Bulukerto village which was affected by the flood has an area of 20,972,832 m2 with a scenario of inundation depth reaching 4,343 m. Then some land cover such as residential land that is inundated by this flood simulation is 0,002 ha. Buildings from residential areas that were flooded reached 209 buildings. Then the area of agricultural land affected is 0,02 ha. In addition, there are also green open spaces affected by this simulation with an inundation area of 0,003 ha.

SCS-CN and GIS-Based Approach for Estimating Runoff in Western Region of Saudi Arabia

Designing reservoir operations, hydraulic structure, and soil erosion management techniques all require an estimation of a potential runoff. Accurate runoff in-formation is typically scarce in Saudi Arabia—a significant challenge for hydrologists. Wadi-Rahjan catchment in Western Saudi Arabia has been taken as a case study to determine the potential runoff estimates. The study integrates the soil conservation service curve number (SCN-CN) technique, remote sensing (RS), and geographical information system (GIS). Critical parameters including the digital elevation model (DEM), land use/land cover (LULC), hydrologic soil groups (HSGs), and rainfall data were also employed. The curve number (CN), which shows the catchment’s reaction to a storm was estimated based on LULC and HSG layers. The CN map obtained and rainfall data were employed in the GIS-based SCS-CN model to develop the potential runoff map. Based on the results of calculations, the study area is classified into three HSGs, namely, B, C, D. Averagely, CN for a normal condition is 90 while wet and dry conditions are 97 and 80, respectively. Results obtained from the SCS-CN method’s calculations reveal a yearly runoff result that varies from 194 mm to 295 mm. A higher percentage of runoff water (35%) in a runoff range from 289 to 295 mm, followed by 24%, ranged 269 to 288 mm. An interesting rainfall-runoff regression evaluation reveals a good 0.90 correlation. Other watersheds in Saudi Arabia may use this method for planning and development.

Evaluation of Hydrological Response of an Agricultural Watershed to Conservation Measures and Land Use Changes: A Case Study

An agricultural watershed falling in the catchment of Godavri basin was selected for the study. Paddy, Maize, Cotton, Red gram, and Vegetables are the major crops grown in the watershed. Severe soil erosion consequent degradation of land and lack of water resources for supplementary irrigation and high dependence on rainfed farming leading to poor crop yields were the major problems in the watershed. With a view to address the issues in rainfed farming compounded by increasing adverse effects of climate change, soil and water conservation measures including area and drainage line treatments from ridge to valley were implemented in the watershed from the year 2009 to 2015 with the active participation of local people with facilitation support by a local civil society organization. With the implementation of the conservation measures, visible impact in terms of increased water availability, change in the land use and increased area under cultivation were reported in the watershed. The present study aimed at assessing the hydrological response of the watershed to the conservation measures and land use changes. As the study watershed is an ungauged one, the hydrological response of watershed was simulated with commonly used SCS-CN model duly validated with additional surface storage capacity created in the watershed. The study revealed highly positive impact of conservation measures and land use changes on hydrological behaviour of watershed. The main observed change in hydrological response of watershed was the decrease in the monsoon seasonal runoff by 33% (from 15 % before taking up catchment management measures to 10 % of seasonal rainfall after the project). The conservation measures were found to facilitate storing excess runoff in the watershed itself contributing to improved soil moisture, groundwater recharge and availability of water. Further, the additional storage capacity of 336 cubic m per hectare as estimated from the present hydrological response study was found to be in very close agreement with actual storage capacity of 322 cubic m per hectare, created with different conservation works taken up in the watershed.

Evaluation of Emergency Response Capacity of Urban Pluvial Flooding Public Service Based on Scenario Simulation.

The evaluation of emergency response capability under different pluvial flooding scenarios is an essential approach to improve the emergency response capability of flood disasters. A new evaluation method of emergency response capacity of urban public services is proposed based on urban pluvial flooding scenario simulation. Firstly, inundation area and depth under different pluvial flooding scenarios are simulated based on the SCS-CN model. Following that, space densities of all indicators include inundation area and depth, road network and the emergency public service institutions. Then, the indicator weight is determined by the combined weighting method of entropy weight and coefficient of variation. Finally, the emergency response capacity index (of each pixel) is calculated based on the graph stacking method. Taking Erqi District, Zhengzhou City as an example, the emergency response capacity of public service under different urban flooding scenarios is evaluated. The results show that the spatial distribution difference of public service emergency response capacity in Erqi District, Zhengzhou City is obvious, and with the increase of the precipitation return period, the high value area of public service emergency response capability decreases gradually and the low value area increases gradually. This method takes into account the specific urban flooding scenario and the layout of public service institutions and road networks that have strong practicability. the results of the evaluation can provide a reference for the construction of urban flood emergency response capacity and provide support for emergency decision-making.

Numerical Approach for Channel Flood Routing in an Ungauged Basin: a Case Study in Kulsi River Basin, India

Flood is the most devastating and frequent disaster in North-East India, resulting in loss of human life and damage of properties. Its deleterious effects can be minimized by appropriate modeling, analysis, and management methods. Such modeling and analyzing techniques are hindered in flood prediction in an ungauged basin due to the lack of hydro-meteorological data. The main objective of this work is to develop a numerical approach for flood routing in an ungauged basin using the rainfall-runoff model and the flood routing models (Muskingum approach, Cunge-Muskingum model, KWM, VPKWM, DWFRM, and MDWMP). The Geographic Information System software has been used to extract the geographical information of the study area. The SCS-CN rainfall-runoff model is employed to obtain the inflow, and lateral inflow hydrographs of the ungauged sub-basins and the routing models are employed to anticipate the flood hydrograph at the outlet of the ungauged basin. The modeling approach is employed to the Kulsi River Basin, India, hypothetically considered an ungauged basin, and the results obtained from the various routing models are compared with the observed data at the outlet of the basin. The performance of the flood routing models is validated by considering nine statical parameters, i.e., RMSE, E-peak, peak flow time error, E-volume, MAE, R-squared, RE, NSE, and KGE. The results reveal that out of all the abovementioned models, MDWMP shows better performance as far as the predictions in ungauged basin is concerned. The Muskingum approach (MA) and DWFRM routing models can also suitably be used in prediction of flood hydrograph at the downstream of an ungauged basin in less gauged river basin reaches.

Development and performance evaluation of SCS-CN based hybrid model.

In this study, a hybrid approach has been used to increase the predictive efficiency of the SCS-CN model. A recently proposed Ajmal model (developed after randomized configuration) that ignored initial abstraction and maximum potential retention has been given the conceptual framework of the SCS-CN model and a new outcome-based hybrid model (Miv) was formulated. A total of 78 watersheds (7817 events) were used for calibration and the remaining 36 watersheds (3967 events) for validation to develop this hybrid model. The numerical value of hybrid model parameters Lc, λ and S were calibrated using calibration dataset and a simple non-linear one-parameter model has been developed. The performance of the Ajmal (Miii) and hybrid model (Miv) was compared with the original SCS-CN method (λ = 0.2 as Mi and λ = 0.05 as Mii). The performance of models was compared by using four statistical error indices i.e. RMSE, NSE, PBIAS, and n(t) and applying ranking and grading system (RGS). The mean RMSE, NSE, PBIAS, and n(t) values were found superior for Miv (5.60 mm, 0.71, 6.97%, 1.15) model followed by Miii (5.98 mm, 0.65, 16.52%, 1.01), Mii (6.27 mm, 0.61, 20%, 0.90) and Mi (6.98 mm, 0.46, 24.2%, 0.72) model for tested watersheds. The hybrid model (Miv) exhibited consistently well performance for all size watersheds. On the basis of the agreement between watershed runoff coefficient (C) and calibrated model parameter (Lc or CN), R2 value was found relatively higher for hybrid model (Miv) than other models.