Direct Runoff Research Articles

Contributions of Climate Change and Human Activities to Changes in Base Flow and Direct Runoff in the Huai River Basin, China

Contributions of Climate Change and Human Activities to Changes in Base Flow and Direct Runoff in the Huai River Basin, China

Developing an Empirical Relations between Nash Model Parameters and Watersheds Topographical Characteristics for Predicting Direct Runoff Hydrograph

The limited availability of the recorded rainfall-runoff data for many watersheds restricts the development and management of different activities of water resources. To overcome this limitation, the Natural Resources Conservation Service (NRCS) for estimating storm excess rainfall and momentum and optimization methods were combined in a mathematical model to estimate the optimal parameters of Nash Instantaneous unit hydrograph (IUH) and resulting direct runoff hydrograph (DRH), using a developed computer program in MATLAB. The available recorded data of 14 storms (out of 18) of four watersheds in northern Iraq have been applied in the calibration stage. An empirical relationship was developed between the average of each IUH optimal parameter (obtained by optimization as an optimal method according to the applied tests) and the effective watershed topographical characteristics. The developed empirical relations were used in the verification stage to estimate the IUH parameters and DRH for the verification storms and compare with that resulted from Haan’s empirical relations and optimization method. The statistical tests showed that the developed empirical relations efficiency was better than that of Haan’s method and close to that of the recorded storm by optimization method, where the average value of the Nash-Sutcliffe Efficiency for the four watersheds resulted from applying the optimization method, Haan’s method and the developed empirical relations were 0.925, 0.587, 0.883 respectively. The results indicated the developed model’s ability to estimate the IUH and direct runoff hydrograph for ungauged watersheds in northern Iraq.

Evaluation of the Storms Direct Runoff Prediction Methods used for Goizha-Dabashan Watershed

The Momentum and Aron & White evaluating methods have been adopted to estimate the Nash Instantaneous Hydrograph parameters (IUH), while the two methods of excess rainfall (Ф-index and Natural Resources Conservation Service (NRCS) were applied in a model using a developed computer program in MATLAB to predict the direct runoff hydrograph for Goizha-Dabashan watershed located in the northeast of Iraq. In the verification stage, both Nash IUH optimal parameters of the storms and the average optimal values of the same parameters estimated in the calibration stage were applied and compared. The statistical tests showed a preference for the NRCS method with the momentum method in estimating direct runoff hydrograph (the average Nash-Sutcliffe Efficiency (NSE) was equal to 0.815 and 0.77 using optimal parameters verification storms and the average calibrated IUH parameters values, respectively). Also, satisfactory results (NSE was equal to 0.77 and 0.76 using storm parameters and the average calibrated IUH parameters values, respectively) were obtained by applying Aron & White with the NRCS methods, which indicated the ability of both methods for estimating direct runoff hydrograph.

Combined Analysis of Net Groundwater Recharge Using Water Budget and Climate Change Scenarios

Estimating the groundwater recharge rate is essential in all groundwater-related fields, including groundwater development, use, management, modeling, and contamination analysis. In this study, we proposed a combined method of water budget and climate change scenario for estimating the net groundwater recharge rate in the Nakdong River watershed (NRW), South Korea. For the climate change scenario method, the representative concentration pathway (RCP) 4.5 and 8.5 climate scenarios were adopted. First, using the water budget method from 2009 to 2018, the net groundwater recharge rate (NGRR) of 12.15–18.10% relative to annual precipitation (AP) was obtained, subtracting direct runoff (DR) of 21.18–25.32% relative to AP, evapotranspiration (EP) of 40.53–52.29% relative to AP, and baseflow of 12.42–17.84% relative to AP, from the AP (865–1494 mm). The average annual NGRR of the NRW was 200 mm (15.59%). Second, the mean NGRRs from 2009 to 2100 under the RCP 4.5 and RCP 8.5 scenarios were anticipated as 8.73% and 7.63%, respectively. The similarity between the water budget and climate change scenarios was confirmed using data from 2009 and 2018. According to the simple climate change scenario, it is predicted that annual precipitation will increase over the years while the groundwater level and net groundwater recharge rate will decrease. Nonetheless, the estimated NGRR by the water budget method in this study possesses uncertainty due to using potential ET instead of actual ET which should be estimated by considering soil water content.

SCS-CN-Based Improved Models for Direct Surface Runoff Estimation from Large Rainfall Events

This study presents a procedure to estimate more accurate direct surface runoff from large rainfall (>25.4 mm)-runoff events. Improved models (M5-M7) are derived by coupling two concepts: (i) initial abstraction as 2% of the total rainfall and (ii) runoff coefficient = degree of saturation. Performance of ten different models including the original SCS-CN method (M1), Mishra and Singh 2002 (M2), Mishra et al. 2006 (M3), Ajmal et al. 2016 (M4), improved models (M5-M7) and their simplified forms (M8-M10) is evaluated using large (7687) number of rainfall events derived from 98 watersheds of USDA-ARS to assess the accuracy of runoff estimation. Quantitatively, it is assessed using seven performance indices, viz., R2, NSE, PBIAS, RMSE, NRMSE, RSR, and MAE; categories; and Ranking and Grading System (RGS). The resulting high values of R2, RSR, RGS, and lowest values of NSE, PBIAS, RMSE, NRMSE, and MAE for the improved models (M5-M7) reveal that improved models performed better than the existing models (M1-M4). Similarly, based on different performance categories, all improved models exhibited superior performance in most of the watersheds than did the existing models. Sensitivity analysis indicated CN to be the most sensitive parameter of the improved model. The proposed model is seen to have overcome the limitations of the original and its previous versions intended for large events and can thus be used for estimating runoff more accurately.

Application of HEC-HMS for the Assessment of Water Availability in Fincha and Didessa Sub-basin, Ethiopia

The water resources availability assessment required for determination of optimal allocation and planning of water resources. This study is mainly focus on the water resources availability in the Fincha and Didessa sub-basin of Ethiopia by using HEC-HMS. The performance of the model was assessed via calibration at gauging station using Relative Volume Error (D), coefficient of determination (R 2 ) and Nash-Sutcliffe Efficiency (NSE) performance coefficients. Then the model was validated using the parameters optimized during model calibration. The availability of water resources assessed at different watershed created to see at local level and finally at outlet point to Main River for each sub-basin separately. The HEC-HMS model shows a good performance Little anger which resulted D=2.58, R 2 =0.75 and NSE=0.63 during calibration and D=4.32, R 2 =0.77 and NSE=0.46 during validation and Neshi D=-1.37, R 2 =0.53 and NSE=0.58 during calibration and D=6.98, R 2 =0.68 and NSE=0.58 during validation for Didessa and Fincha Sub basin respectively. The parameters optimized at little Anger and Neshi gauging station was used for flow simulation to assess water resources availability on monthly and annual basis. The flow components were also separated at small catchment considered for all sub-basin. The result shows that high percentage of flow occupied by Direct Runoff for both Didessa and Fincha sub basins. So the available water in the sub-basins should be allocated fairly and accurately for water resources projects for effective utilization of the country water resources. Keywords: Fincha and Didessa sub-basin, HEC-HMS, Water Resources Availability. DOI: 10.7176/JEES/10-11-05 Publication date: November 30 th 2020

Sensitivity analysis of relationships between hydrograph components and landscapes metrics extracted from digital elevation models with different spatial resolutions

Evaluation of sensitivity of hydrograph components and landscape metrics extracted from various spatial resolutions reveals relationships between landscape metrics and outflow properties with the lowest error. In the present study, 14 Digital Elevation Models (DEMs) with different resolutions derived from a vector and raster-radar source were analyzed to evaluate sensitivity of relationships between simulated hydrograph components and landscape metrics using multiple regression methods in the Galazchai Watershed, West Azerbaijan Province, Iran. To this end, DEM, slope, flow length and direction and time of concentration were developed in the vector and raster scales of 1:25000 and Advanced Land Observing Satellite-1 (ALOS) with different resolutions using ArcGIS 10.5 and ArcHydro software. Accordingly, 588 Direct Runoff Hydrographs (DRHs) were produced and clustered using Clark's Instantaneous Unit Hydrograph (IUH) model. The results showed that the best regression fits for flood volume and peak discharge were determined with Number of Disjunct Core Areas (NDCA) and Patch Density (PD) landscape metrics. Furthermore, the best regression fitted for time to peak and base time were observed with Core Area (CA) and Normalized Landscape Shape Index (NLSI) landscape metrics. In addition, the sensitivity analysis shows that the most sensitive spatial resolutions in modeling relationship between flood volume and peak discharge were determined at 5, 10, 20, and 30 m. The results revealed that hydrograph components in association with landscape metrics had high sensitivity to spatial resolutions, while the relationships between hydrological components and landscape metrics without considering the optimal spatial resolutions resulted in unacceptable results.

Hydrological Modelling of Bina River Basin in Madhya Pradesh, India

Rainfall-runoff models have been widely used through the last century all over the world. These models help to build a trustworthy relationship between the precipitation and runoff. The relationship between rainfall and runoff is essential in a catchment for hydrologic analysis and design. In the current paper, our main objective is to compute runoff by employing two hydrological models namely SCS CN and RRL toolkit Australian Water Balance Model (AWBM) and to check the which model is more suitable for runoff estimation in the Bina basin. The SCS CN method is an empirical approach for estimation of Direct Runoff.

Quantitative assessment of inundation risks from physical contributors associated with future storm surges: a case study of Typhoon Maemi (2003)

Future storm-induced inundation risks were assessed by performing storm surge modeling based on Typhoon Maemi (2003) under the generic climate change scenarios proposed by IPCC AR5. The three physical factors governing the projected aggravation of inundation damage in a coastal basin (i.e., sea-level rise (SLR), direct runoff (DR) and tropical cyclones (TCs)) were defined and considered in the modeling both individually and in combination. With the application of a coupled hydrodynamic–hydrologic model, the inundation extent during the storm event under both current and year 2100 climate conditions was evaluated, and the impact of each factor on the inundation risk was identified. The intercomparison among the results revealed that SLR was the most influential single flooding driver aggravating the future inundation risk, and TC intensification was two-thirds as influential as SLR. However, DR was predicted to make a nearly negligible contribution and to have a minimal impact despite its significant projected increase in the future. Apart from the contributions of these three factors to aggravating the inundation level, the ways in which they affected the inundation risk were quite distinct. Additionally, the result considering both SLR and TC intensification demonstrated that nonlinear interactions between these factors can occur and further amplify the inundation damage. Finally, it was revealed that, depending on the level of the climate change projection, future storms with intensified rainfall and TC properties are likely to cause the maximum projected inundation damage in the study area to increase by up to 28.7% in inundation extent and by 236.6% in inundation volume relative to the current conditions without altering the spatial pattern of the inundation depth distribution.

The Influence of Riparian Areas on Direct Surface Runoff of Precipitation Events

This study aims to estimate the effect of different land uses around watercourses on runoff following extreme precipitation events and, consequently, on the mitigation of these effects. The study area is a rural watershed in the state of Rio Grande do Sul, Brazil. After characterizing the area, we estimated the surface runoff of the January 2009 precipitation event, which caused two casualties: losses in soil and productive area, as well as over US$ 300,000.00 in damages to the water supply system. Subsequently, simulations were performed considering different land uses and riparian areas under different precipitation levels. The results indicate that conserving riparian forests in the surroundings of watercourses decreases direct surface runoff, whereas intense soil use in these areas favors runoff increase.

Investigation of direct runoff in the intensive farming system of upstream Merawu watershed, Indonesia

Merawu watershed is located at Banjarnegara district and categorized as degraded watershed in the Serayu river basin. Upstream area in the Merawu watershed is a mountainous area of 1,500 m a.s.l., with steep slopes and high rainfall intensity. Upstream Merawu has an important function as recharge area, protect the downstream and water supply for the Merica reservoir. Forest conversion to intensive farming practices have produced large portion of erosion, surface runoff and water pollutant. Understanding the surface runoff changes in the forest conversion to intensive farming practices is important. Investigations of direct runoff in the intensive farming system in upstream area of Merawu watershed were observed using two small catchment experiments. Catchment for intensive farming system was compared to non-disturbed catchment of Pine forest. Surface disturbances associated with soil tillage, fertilization, pesticides and mulching during 2-3 months of planting reduced the soil capacity to control rainfall. During 1-year investigation, total direct runoff (DRO) in intensive farming catchment was 360.05 mm or 34.4% of rainfall or 1.63 times higher than that in the Pine forest catchment. Unit hydrograph analysis found the direct runoff coefficient was 9.4% or 1.7 times higher than that in the Pine forest catchment. This study found the important function of canopy interception, forest floor interception, soil management and infiltration to control the direct runoff in the catchment.

Sensitivity of Direct Runoff to Curve Number Using the SCS-CN Method

This study explores the impact of runoff curve number (CN) on the hydrological model outputs for the Morai watershed, Sindh-Pakistan, using the Soil Conservation Service Curve Number (SCS-CN) method. The SCS-CN method is an empirical technique used to estimate rainfall-runoff volume from precipitation in small watersheds, and CN is an empirically derived parameter used to calculate direct runoff from a rainfall event. CN depends on soil type, its condition, and the land use and land cover (LULC) of an area. Precise knowledge of these factors was not available for the study area, and therefore, a range of values was selected to analyze the sensitivity of the model to the changing CN values. Sensitivity analysis involves a methodological manipulation of model parameters to understand their impacts on model outputs. A range of CN values from 40-90 was selected to determine their effects on model results at the sub-catchment level during the historic flood year of 2010. The model simulated 362 cumecs of peak discharge for CN=90; however, for CN=40, the discharge reduced substantially to 78 cumecs (a 78.46% reduction). Event-based comparison of water volumes for different groups of CN values—90-75, 80-75, 75-70, and 90-40 —showed reductions in water availability of 8.88%, 3.39%, 3.82%, and 41.81%, respectively. Although it is known that the higher the CN, the greater the discharge from direct runoff and the less initial losses, the sensitivity analysis quantifies that impact and determines the amount of associated discharges with changing CN values. The results of the case study suggest that CN is one of the most influential parameters in the simulation of direct runoff. Knowledge of accurate runoff is important in both wet (flood management) and dry periods (water availability). A wide range in the resulting water discharges highlights the importance of precise CN selection. Sensitivity analysis is an essential facet of establishing hydrological models in limited data watersheds. The range of CNs demonstrates an enormous quantitative consequence on direct runoff, the exactness of which is necessary for effective water resource planning and management. The method itself is not novel, but the way it is proposed here can justify investments in determining the accurate CN before initiating mega projects involving rainfall-runoff simulations. Even a small error in CN value may lead to serious consequences. In the current study, the sensitivity analysis challenges the strength of the results of a model in the presence of ambiguity regarding CN value.

Assessment of storm direct runoff and peak flow rates using improved SCS-CN models for selected forested watersheds in the Southeastern United States

Study regionSoutheastern United States Study focusThe objective was to evaluate the ability of two modified SCS-CN models to predict direct runoff (DRO) and peak discharge rate (Qp) for selected storm events in three forested watersheds in the region - one low-gradient system in South Carolina, two high-gradient upland systems in North Carolina, and a mid-gradient upland system in Arkansas. New hydrological insights for the regionThe calculated peak discharge rate Qp values by all methods were unsatisfactory when using the default pond and swamp adjustment factor (Fp) value of 0.72 recommended in the SCS TR55 guideline, indicating that use of the default Fp value may result in erroneous Qp estimates for forest watersheds with high retention capacities. These findings, indicating the superiority of the modified Sahu-Mishra-Eldo (SME_m) method to the original SCS method in runoff calculations and substantially lower Fp values in the associated Qp method, are significant for hydrologists and engineers who frequently apply the methods in design of storm water management structures including road culverts on forested landscapes.

Study of Modelling Synthetic Unit Hydograph Using ITB-1 Method (Case Study: Upstream Siak Watershed)

Analysis of unmeasured flow rates in watershed with the Syntetic Hydrograph Unit (SUH) Method is the most practical and simple method. This method requires watershed characteristics as river length and watershed area. Calculation and flow rate data are very useful in the development of water resources science and civil building planning especially in water construction work. Today, the Syntetic Unit Hydrograph (SUH) Method has been widely developed and most recently the ITB-1 Syntetic Unit Hydrograph (SUH) Method. The reliability of SUH ITB-1 in Sungai Tapung Kanan and Sungai Tapung Kiri shows good performance. This is indicated by the accuracy of the volume of the Tapung Kanan River 96.30% and the accuracy of the Tapung Kiri River 99.88%. The volume control ratio / direct run off (DRO) Sungai Tapung Kanan 1,00006 and Sungai Tapung Kiri 1,000088 (close to 1). While the peak discharge produced by Tapung Kanan River is 39,950 m3/ sec and Tapung Kiri River is 38,867 m3/sec.

Assimilation of Satellite-Based Data for Hydrological Mapping of Precipitation and Direct Runoff Coefficient for the Lake Urmia Basin in Iran

Water management in arid basins often lacks sufficient hydro-climatological data because, e.g., rain gauges are typically absent at high elevations and inflow to ungauged areas around large closed lakes is difficult to estimate. We sought to improve precipitation and runoff estimation in an arid basin (Lake Urmia, Iran) using methods involving assimilation of satellite-based data. We estimated precipitation using interpolation of rain gauge data by kriging, downscaling the Tropical Rainfall Measuring Mission (TRMM), and cokriging interpolation of in-situ records with Remote Sensing (RS)-based data. Using RS-based data application in estimations gave more precise results, by compensating for lack of data at high elevations. Cokriging interpolation of rain gauges by TRMM and Digitized Elevation Model (DEM) gave 4–9 mm lower Root Mean Square Error (RMSE) in different years compared with kriging. Downscaling TRMM improved its accuracy by 14 mm. Using the most accurate precipitation result, we modeled annual direct runoff with Kennessey and Soil Conservation Service Curve Number (SCS-CN) models. These models use land use, permeability, and slope data. In runoff modeling, Kennessey gave higher accuracy. Calibrating Kennessey reduced the Normalized RMSE (NRMSE) from 1 in the standard model to 0.44. Direct runoff coefficient map by 1 km spatial resolution was generated by calibrated Kennessey. Validation by the closest gauges to the lake gave a NRMSE of 0.41 which approved the accuracy of modeling.

Effect of Time-Area Percent Curves in Development of Clark Model Unit Hydrograph

This paper describes the effect of time – area percent curves in the development of Clark model unit hydrograph. This hydrology modelling study refers to event base modeling in order to derive the unit hydrograph from Clark instantaneous unit hydrograph. For this study, Kelani river basin up to Hanwella gauging site has been represented as the study area. Hydrologic Modelling System software developed by HEC, USA (HEC-HMS) has been used for the development of unit hydrographs under the Clark UH transform model. Three numbers of different time – area percent curves of Kelani river basin have been asynchronously used as input to the Clark UH transform model in order to obtain different simulations. The parameters, time of concentration Tc and storage coefficient R values were calibrated and validated individually, against the various percent curves for the future analysis. The best suitable percent curve is identified based on the goodness of fit criteria, Nash-Sutcliffe Efficiency (NSE) with high accuracy. For the Loss model, initial and constant rate method was preferred. In the Meteorological Model, Gaged weight was considered for rainfall analysis. For the Transform Model or Direct Runoff Model, Clark UH is considered. For the Base flow model Recession, constant option was preferred. The Calibration (manual and automatic) was conducted for the storm events of May 2017, December 2014 and November 2012.Validation was conducted for the storm event of June 2014. The calibration and validation process was conducted for analyzing the hourly rainfall-runoff data for storm events observed during the monsoon seasons of the relevant years. The conclusions of the study would be very much applicable for the key personnel for taking structural and non-structural measures against the flood menace which is a frequent challenge over the study area concerned.

Investigating Parameters of Geomorphic Direct Runoff Hydrograph Models

Formulation of rainfall runoff models and identification of their parameters is difficult step especially for catchments having scanty or no data. Parameters of geomorphic instantaneous unit hydrograph (GIUH) models have been investigated in this research. Recorded data of Shahpur Dam Catchment, Pakistan was used for developing direct runoff hydrograph model. Satellite imageries of the catchment were processed using ArcGIS 10.1 to estimate geomorphologic parameters. The rainfall and runoff data for 10 events was collected from Meteorological Department Lahore and from Small Dam Organization, Rawalpindi, Pakistan. Rainfall data was analyzed and excess rainfall was estimated using Percent Runoff Method. Using estimated geomorphologic parameters the ordinates of GIUH- Nash Model were obtained by standard equations of Nash instantaneous unit hydrograph (IUH). These ordinates of Nash-IUH, were converted into the ordinates of direct runoff hydrographs through their convolution with the excess rainfall. The results of model were evaluated on the basis of their deviation from the observed runoff data. Statistical parameter Nash-Sutcliffe Coefficient and percent error between observed and simulated direct runoff were used for this purpose. The impact of using digital elevation models (DEM) of two different resolutions; 30 and 90 m, was then investigated. It is observed that the geomorphic parameters are affected due to DEM’s resolution. Hence the resolution of DEM impacts the direct runoff as well.

Mapping the capacity of concave green land in mitigating urban pluvial floods and its beneficiaries

Pluvial floods can exert significant pressure on urban sustainability and human wellbeing during rapid urbanization. Rapid urbanization and exacerbated flooding have stimulated investigations of green land’s role in mitigating urban flooding in China. The newly applied “Sponge City” plan considers the concave green land (CGL) as an effective tool in mitigating pluvial floods. However, its capacity and beneficiaries still need to be elucidated. This paper fills this research gap by integrating urban flood simulation, scenario analysis, and mitigation assessment in central Shanghai, China. It reveals that CGL could not only mitigate direct runoff and inundation, but also reduce population exposure and enhance community resilience. CGL with a depth of 0.10–0.20 m can mitigate direct runoffs by 23.63–98.35% and inundation extents by 26.09–82.41%, resulting in a slide of the exposed urban population by 0.40–1.04 million persons and the exposed elders by 0.04–0.12 million persons. Moreover, the effectiveness of CGL varies spatially implying for a sound spatial planning of CGLs and a potential combination with other flood mitigation measures. These findings could help cities particularly in developing countries to adapt to rising pluvial flooding through urban planning and nature-based flood mitigation measures.

Assessing the Impact of Urbanization on Direct Runoff Using Improved Composite CN Method in a Large Urban Area.

Urbanization is one of the most widespread anthropogenic activities, which brings a range of physical and biochemical changes to hydrological system and processes. Increasing direct runoff caused by land use change has become a major challenge for urban ecological security. Reliable prediction of the quantity and rate of surface runoff is an inherently difficult and time-consuming task for large ungauged urban areas. In this study, we combined Geographic Information System and remote sensing technology with an improved Soil Conservation Service curve number model to evaluate the effects of land use change on direct runoff volume of the four-ring area in Shenyang, China, and analyzed trends of direct runoff at different scales. Through analyzing trends of direct runoff from 1984 to 2015 at different scales, we explored how urbanization and other potential factors affect direct runoff changes. Total direct runoff volume increased over time, and trends varied from the inner urban area to suburban area. Zones 1 and 2 had a tendency toward decreasing direct runoff volume and risks, while Zones 3 and 4 showed gradual increases at both regional and pixel scales. The most important influence on direct runoff change was urban surface change caused by urbanization. This study presents a framework for identifying hotspots of runoff increase, which can provide important guidance to urban managers in future green infrastructure planning, in the hopes of improving the security of urban water ecological patterns.

Dampak Perubahan Tataguna Lahan Terhadap Keseimbangan Air Wilayah Pulau Seram. Studi Kasus : Das Way Pia Di Kabupaten Maluku Tengah, Provinsi Maluku

This research was conducted to estimate the values of parameters which described the physical characteristics of catchments area and monthly water balance components, and understand the sensitivity of the water balance components to change in the parameter value due to the physical changes occurring in Way Pia catchments area, Ceram Island. The method used involved calculation of the regional water balance in the current time (normal) and during the time of land use change, using an evapoclimatonomy model. The main model inputs were monthly rainfall, global radiation and run off. Analyses of data were conducted with five steps as follows : (1) mathematical formulation of the evapoclimatonomy model, (2) algorithm formation and transfer to computer code, (3) establishment of parameters and calibration, (4) validation of model, and (5) experimentation of model. The current physical conditions of Way Pia catchments area were characterized by: average of parameter value of albedo, a = 0,16; rainfall threshold, Pn = 100 mm; surface run off ratio, np = 0,23; evapority, ep = 0,42; measure of soil water loss from sub surface, vN = 0,12; and measure of evapotranspiration of soil water from sub surface, vE = 0,20. Model output of the current water balance consisted of annual value of soil moisture, m = 272 mm; total evapotranspiration, E = 1393 mm, and total run off, N = 920 mm. The land use change in the form of land clearing will increase the parameter values of a and np, which affect on increasing of direct run off (N') of 13% as compared to current conditions.