Urban Storm Runoff Inlet Hydrograph Study, Volume 5, Soil-Cover-Moisture Complex: Analysis of Parametric Infiltration Models for Highway Sideslopes

The main objective of this study is to develop an accurate design method for computing inlet hydrographs of surface runoff, with average recurrence intervals of 10, 25, and 50 years, from typical urban highway by flood routing technique. The boundary-value problem of one-dimensional infiltration resulting from rainfall is formulated and solved numerically on a digital computer. The numerical solutions of this idealized mathematical model is used as a basic testing tool in the subsequent analysis of various parametric infiltration models including the Green-Ampt, Kostiakov, Philip, Horton, and Holtan equations. The time of ponding is shown to be the most important parameter in a parametric infiltration model and can be expressed in terms of other parameters in the model as well as the rainfall intensity. The values of all the model parameters in the model as well as the rainfall intensity. The values of all the model parameters are determined to be fairly constant for a soil having the same initial and upper boundary (soil surface) conditions. Use of the Green-Ampt, Kostiakov, and Philip type models for the prediction of the infiltration rate before and after ponding is proved to be satisfactory. For engineering practice, the standard infiltration-capacity curves for soil-cover-moisture complexes representing urban highway sideslopes are empirically developed based on the unique selection of the Soil Conservation Service runoff curve number. Validity of typical standard curves so developed were experimentally examined in the Utah Water Research Laboratory stormflow experiment facility

EVALUATING THE EFFECTIVENESS OF WEEP BERM SYSTEMS FOR TREATING RUNOFF FROM A HORSE MUCK COMPOSTING OPERATION

Two contour weep berms systems were designed and implemented to evaluate their performance at mitigating water quantity problems from a horse muck composting operation. The field-scale study focused on the hydrologic response of a standard contour weep berm and a modified contour weep berm. The modified contour weep berm incorporated a woodchip trench upgradient of a typical standard contour weep design. Monitoring occurred from July 2011 through spring 2012. Eight storm events produced measureable runoff for the standard contour weep berm; however, only five storm events produced measurable runoff for the modified contour weep berm. The largest storm event occurred on November 27, 2012 with rainfall depth of 49.0 mm. This storm event generated a total runoff volume of 183.1 m3 and 188.5 m3 for the standard and modified contour weep berms, respectively. All runoff produced from the storm events during the monitoring period was completely detained and infiltrated. No runoff was released from the horse muck composting facility through the passive dewatering system to down-gradient vegetative filter strips during the monitoring period

Modelling water-harvesting systems in the arid south of Tunisia using SWAT

In many arid countries, runoff water-harvesting systems support the livelihood of the rural population. Little is known, however, about the effect of these systems on the water balance components of arid watersheds. The objective of this study was to adapt and evaluate the GIS-based watershed model SWAT (Soil Water Assessment Tool) for simulating the main hydrologic processes in arid environments. The model was applied to the 270-km(2) watershed of wadi Koutine in southeast Tunisia, which receives about 200 mm annual rain. The main adjustment for adapting the model to this dry Mediterranean environment was the inclusion of water-harvesting systems, which capture and use surface runoff for crop production in upstream subbasins, and a modification of the crop growth processes. The adjusted version of the model was named SWAT-WH. Model evaluation was performed based on 38 runoff events recorded at the Koutine station between 1973 and 1985. The model predicted that the average annual watershed rainfall of the 12-year evaluation period (209 mm) was split into ET (72%), groundwater recharge (22%) and outflow (6%). The evaluation coefficients for calibration and validation were, respectively, R-2 (coefficient of determination) 0.77 and 0.44; E (Nash-Sutcliffe coefficient) 0.73 and 0.43; and MAE (Mean Absolute Error) 2.6 mm and 3.0 mm, indicating that the model could reproduce the observed events reasonably well. However, the runoff record was dominated by two extreme events, which had a strong effect on the evaluation criteria. Discrepancies remained mainly due to uncertainties in the observed daily rainfall and runoff data. Recommendations for future research include the installation of additional rainfall and runoff gauges with continuous data logging and the collection of more field data to represent the soils and land use. In addition, crop growth and yield monitoring is needed for a proper evaluation of crop production, to allow an economic assessment of the different water uses in the watershed

Surface Hydrologic Modeling and Analyzing Watershed Hydrologic Response to Landcover Change

Urban flooding is the most frequently occurring disaster in rapidly urbanizing cities. Rapid urbanization in general, is characterized by an increase in the total impervious surface area, which means less soil cover for the stormwater to infiltrate and a greater volume of runoff from the area in case of a storm event. This increased volume of surface runoff, if not drained, results in urban flooding. Urban flooding can cause serious economic and environmental damages by disrupting transportation and spreading pollution. It is therefore, essential to understand the cause, behavior and effects of urban flooding so as to minimize the risks and costs associated with urban floods. Hydrologic models are useful tools for understanding hydrologic processes and for designing urban stormwater drainage infrastructure to reduce the risks of floodings. This research aims to study urban hydrology by estimating surface runoff from an urban area using an event based distributed parameter hydrologic model. In this research, an event-based distributed parameter hydrologic model is developed, which uses Green-Ampt infiltration model to estimate the surface runoff from a given catchment. The developed model is tested on two small catchments. The ‘rainfall-runoff modeling’ part of the developed model is calibrated for the rainfall events of May 22, 2017 and, May 24, 2017 over the Moores Run study area, and, validated for the rainfall event of April 17, 2017. The ‘flood-modeling’ part of the developed model is validated for the rainfall event of Sep 11, 2012 over the Parking-lots area at UNLV. The results of the rainfall-runoff simulation and flood depth and extent estimation for different land-cover change scenarios over the Parking-lots catchment is also provided. The testing on Moores Run study area resulted in calibration at 30-m resolution DEM and a hydraulic conductivity value of 0.19 cm/hr. for soil group D. The error in the model’s estimation of the catchment area is 7.75%. The model over-predicted the runoff volume from the catchment for the first rainfall event while under-predicted the runoff volume from the catchment for the second rainfall event. The average error in estimation of the runoff volume is 1.8%. The model also over-predicts the ‘time-to-peak’ and under-predicts ‘peak runoff’ in both cases. The average of RMSE between the predicted hydrograph and actual hydrograph for the two rainfall events is 0.0071 m3/s in calibration, and, 0.011 m3/s in validation. The testing on UNLV Parking-lots area resulted in calibration at 10-m resolution DEM. For the rainfall event of Sep 11, 2012, the model predicts over predicts the peak flood depth and under-predicts the maximum extent of flooding. The error in flood depth estimation is found be 12.9%. From watershed hydrologic response to landcover change analysis, it is observed that Manning’s roughness coefficient doesn’t affect the total volume of runoff, however, the time to peak is significantly delayed for landcover with higher values of Manning’s roughness co-efficient. This research provides an insight into surface hydrologic modeling. It also provides an overview of calibration against DEM resolution and hydraulic conductivity values. Finally, it provides an understanding of watershed hydrologic response to different landcovers with various Manning’s roughness values

Arc SWAT Model Integrated with Arc GIS - Based Evaluation of Land Use /Land Cover Change on the Hydrological Response of Muga Watershed, Abbay Basin, Ethiopia

The study has shown the integration of Arc SWAT with Arc GIS and remote sensing tool are helpful analyze and evaluate both spatial and temporal land use/cover dynamics. It has also shown that Arc SWAT is an effective tool in analyzing the impacts of land use/cover changes on stream flow in areas with limited readily available data. This study is mainly focusing on the investigation of the impacts of land use / land cover changes on the stream flow of Muga watershed which is located in the East Choke Mountains watersheds, Upper Abbay Basin, East Gojjam Zone, Amhara Regional state, Ethiopia. Soil and Water Assessment Tool (SWAT) model were used it investigate the impact of land cover change on the stream flow. For this study SWAT Simulation is used in identifying the most vulnerable sub basins to the stream flow and sediment load changes of Muga watershed. The model was calibrated and validated using historic Stream flow data. The model was calibrated using stream flow data from 1993 to1998, validated from 1999 to2002. The R2 and NSE values were used to examine model performance and the result indicates 0.81 and 0.87 to R2 and 0.80 and 0.86 to NSE during calibration and validation respectively. The result of this analysis indicated that the mean monthly stream flow for wet months had increased by 17.75m3/s while the dry season decreased by 12.76m3/s during the 1995-2013 period due to the land use and land cover change. The highest annual surface runoff was attributed by sub basin 5 whereas sub basin 6 contributes the highest ground water respectively for 1995, 2003 and 2013 land cover maps. In terms of sediment yield, sub basin 1 contributes a maximum load for the study periods. Keywords: Arc SWAT, Arc GIS, Land Use /land cover change, Muga Watershed DOI: 10.7176/CER/13-2-01 Publication date: April 30th 202

Structural Best Management Practices (BMPs) and hydrological effects modelling using swat for urban watershed

Orientador: Prof. Dr. Cristovao V.S. FernandesDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Recursos Hídricos e Ambiental. Defesa : Curitiba, 15/03/2019Inclui referências: p. 128-141Resumo: As Best Management Practices (BMPs) têm sido usadas como solução para mitigação de condições de pós-desenvolvimento em bacias urbanas e rurais. Estes dispositivos regulam vazões e volumes, além de capturar poluentes do escoamento superficial usando vários mecanismos. Estes dispositivos têm sido estudados e seu uso disseminado em vários países. Concomitantemente, o melhoramento de modelos de transporte e destinação de constituintes para investigar os efeitos, algoritmos para otimizar a busca por locais ótimos de instalação e facilitação da avaliação de entradas e saídas trouxe à luz vários desafios no que tange a modelagem dos fenômenos, incluindo a seleção de escalas de dimensão e tempo adequadas à representação dos fenômenos. A revisão de literatura demonstra uma fronteira clara entre usar inputs massivos de dados e computação exaustiva em modelos para descrição detalhada dos processos ou a adoção de abordagens mais simplificadas que capturem áreas maiores a custos menores de levantamento de dados. Neste estudo o Soil and Water Assessment Tool (SWAT) é utilizado como solução harmônica para modelagem em bacias com usos do solo mistos. Para vencer os desafios acima citados, BMPs são tratadas como zonas de recarga, isto é, zonas com Números de Curva (CN) menores. A localização destes dispositivos no modelo é realizada utilizando critérios consolidados de viabilidade através de ferramentas já desenvolvidas. Quatro cenários de redução percentual são utilizados para avaliação das melhoras de fluxo nas escalas da Hydrological Response Unit (HRU), subbacia e curso do rio(reach): 10%, 30%, 50% e 70%. As mudanças foram avaliadas na escala diária e anual, usando aplicações desenvolvidas em Python para automatizar a parametrização do modelo e a entrada e saída de dados. O estudo foi bem-sucedido em conceber a geração de múltiplos cenários, assim como em produzir ferramentas que auxiliem a entrada e saída de dados. Os resultados demonstram que a criação de zonas de recarga é mais eficaz em regiões onde há mais capacidade de retenção do solo. Do contrário, a redução do escoamento superficial tende a chegar em um limite, a partir do qual não há mais roteamento do escoamento superficial. Em HRUs e subbacias onde as condições de solo são favoráveis, a dinâmica de roteamento superficial e subsuperficial é modificada, fazendo com que a recarga dos aquíferos aumente e as recessões sejam mais lentas. Em geral, não são visíveis efeitos na escala da subbacia e no curso principal do rio, uma vez que muito do escoamento superficial é roteado como escoamento lateral ou fluo de subsuperfície. Além disso, a superposição dos efeitos para o resto da bacia é muito pequena na escala diária. Palavras-chave: SWAT. Bacias Urbanas. Python. Best Management Practices Hidrologia.Abstract: Best Management Practice (BMP) devices have been employed as a solution for both agricultural and urban watershed post-development effect mitigation. These devices regulate flow and capture runoff pollutants using various mechanisms. Such devices have been studied and its use disseminated in several countries. Concurrently, the enhancement of pollutant fate and transport models to assess the effects, search for optimal locations and facilitate inputs has brought to light several challenges concerning the modelling of physical phenomena, especially the one related to selecting time and size scales for adequate representation. The literature revision demonstrates that a clear boundary between using massive data inputs and computation-exhaustive models for thorough process description or more simplified approaches that capture larger areas at a more affordable data cost has limited the comprehension and description of BMP hydrological processes at the subbasin and watershed scale. In this study, SWAT is used a harmonic solution for modelling mixed land-use watersheds. To overcome the challenges stated, BMPs are treated as recharge - lower Curve Number (CN) zones, in feasible scenarios generated using an pre-built-tool and consolidated feasibility topographic, hydrological and space-distribution features. Four scenarios were generated: 10, 30, 50 70% CN reductions were tested and evaluated at the daily HRU/subbasin and subbasin yearly average scales, using developed applications for automating the parameter change and Input/output operations. The study was successful in automating the BMP scenario generation and multiple scenario generation as well as output data analysis. Results show that the creation of recharge zones is more effective at regions where more soil storage is available. Otherwise, runoff reduction tends to reach a limit. In HRUs and subbasins where soil conditions are favorable, the entire soil water and groundwater flow dynamics is modified, causing aquifer recharge to increase on average and recessions to be slower. Generally, no effects can be noticed at the subbasin o reach scale, as much of the runoff is also routed either as lateral flow or groundwater flow. The superposition of such effects to the rest of the watershed results in small differences at the daily scale. Keywords: SWAT. Urban watersheds. Python. Best Management Practices. Hydrology

Impact of Using Spatially Distributed Soils Information on Flood Hydrograph Simulation with HEC-HMS

Hydrologic rainfall-runoff models employ numerical equations to simulate the soil absorption of rainfall and resulting runoff. A number of methods have been developed to model these processes, but the parameters used to define these methods can be difficult to directly measure due to the variable nature of soil properties. They often rely on estimation of hydraulic and hydrologic parameters and calibration to produce accurate results. A challenge with runoff method parameterization is the need for oversimplification using a lumped modeling approach. While distributed hydrologic modeling techniques are now available, distributed runoff methods are limited in use due to the tradition of lumped modeling and lack of widely available runoff parameter datasets. This study sought to define modeling parameters for three runoff methods based on physical soil data contained within the Soil Survey Geographic (SSURGO) database for lumped and distributed modeling approaches. These parameters were defined for 1-foot and 3-foot soil depths for estimating controlling influences on infiltration. The methods investigated are the Deficit and Constant method, the Green and Ampt method, and the SCS Curve Number method. The Salt Creek Basin located in southeast Nebraska was the pilot basin for this study. The basin was modeled using the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) software package. The model was adapted to the basin using ArcGIS and the HEC-GeoHMS extension. Three different precipitation events were modeled with the simulated runoff hydrographs at seven locations compared to the observed data to assess the model performance. Several trends in the quality of loss parameters were observed. First, Deficit and Constant and Green and Ampt runoff methods produced runoff hydrographs that closely matched observations. Second, distributed loss parameters for these two methods produced more accurate results than their lumped counterparts. Third, the shallower soil depth parameters produced marginally better hydrographs than their counterparts. Finally, the SCS Curve Number method was able to produce accurate peak flow and runoff volume estimates, but performed poorly with the hydrograph timing. Advisor: Ayse Kili

A Study of DRAINMOD-Urban For Enhanced Bioretention Cell Modeling

Bioretention has become a leading infiltration-based stormwater control measure for mitigating urban hydrology by reducing urban stormwater runoff volumes and peak flows. Despite widespread field and laboratory studies, less investigation has been directed toward effectively modeling these systems. This is critical, as modeling of bioretention systems provides an avenue for evaluating their effectiveness prior to devoting time and resources into installation. Many hydrologic models capable of simulating bioretention consist of lumped parameters and simplifications that do not fully account for fundamental hydrologic processes such as soil-water interactions. One model, DRAINMOD, has overcome many limitations of other models by incorporating the soil-water characteristic curve (SWCC) to provide better analysis of soil moisture conditions within a bioretention cell and offering better drainage configurations such as an internal water storage (IWS) zone. DRAINMOD is an agricultural drainage model that has shown promise when applied to bioretention systems but operates at a daily temporal scale which does not capture rapid changes in urban hydrology. This study begins by modifying DRAINMOD to adapt to the flashy nature of urban hydrology and bioretention systems in a new model named DRAINMOD-Urban. The performance of DRAINMOD-Urban established that it can produce output hydrographs that represent measured drainage and overflow from a bioretention system while still maintaining calibrated volumes of outflow similar to DRAINMOD. Next, DRAINMOD-Urban was compared to the LID module of the commonly used hydrologic model, the U.S. Environmental Protection Agency (EPA) Stormwater Management Model (SWMM). DRAINMOD-Urban produced better drainage hydrographs but SWMM was very accurate at predicting measured drainage (NSE=0.77-0.94) and overflow (NSE=0.67-0.81) volumes. Pedotransfer functions (PTF) were used to derive the SWCC and vi saturated hydraulic conductivity required for DRAINMOD-Urban and model performance was compared among measured and PTF-derived soil properties. This study showed that a calibrated DRAINMOD-Urban can perform equally well with a SWCC that is measured and calculated using the ROSETTA PTF. These investigations provide a better understanding of how DRAINMOD-Urban has enhanced the field of bioretention cell modeling at the site-scale

INFILTRATION CHARACTERISTICS OF SUBSURFACE GRAVEL FILTRATION SYSTEMS FOR STORMWATER MANAGEMENT

Increased stormwater runoff due to the construction of impervious surfaces is a major issue in urban environments, causing combined sewer overflows, erosion in natural waterways, and damage to infrastructure. Subsurface gravel filter (SGF) system, a type of Green Stormwater Infrastructure (GSI), can effectively reduce stormwater runoff volumes and peak flows by infiltrating runoff. Current GSI design guidelines require that these systems be statically sized to store the 24-hour storm depth equaled or not exceeded approximately 90% of the days with rainfall. Across the United States, this design depth is roughly equal to 2.5 centimeters (1 inch) of rainfall. This sizing technique does not account for the dynamics of system performance such as horizontal infiltration through the sides of the systems, unsaturated soil conditions, or the dynamic nature of runoff generation. By neglecting these factors, subsurface infiltration systems may end up being oversized for desired runoff reduction objectives. For this study, the hydrologic performance of SGF systems was evaluated through a combination of monitoring data and computer modeling. Monitoring data was collected for two SGFs in Dover, NH which are statically designed, according to NH stormwater regulations, to capture and treat the runoff from 1-inch of rainfall. One system is located under Grove St and was found to infiltrate substantial volumes of runoff even though the soils surrounding the system were found to have a relatively low hydraulic conductivity (i.e. \u3c0.5 inches per hour). On average, over the 1-year monitoring period, the Grove St SGF infiltrated 84% of the runoff it collected. The second system, which was located under the parking lot of the Seacoast Kettlebell workout center, did not meet design expectation as it infiltrated negligible volumes of runoff during each storm event. The extremely low hydraulic conductivity of the soils at the Kettlebell site, effects of high groundwater level, and close proximately of the system to Berry Brook appear to have severely limited infiltration. Analysis of the systems with three computer-based infiltration models, including an unsaturated flow model, a Green-Ampt model, and a unit-gradient, saturated flow model, showed that system performance was highly dependent on horizontal infiltration. The unsaturated properties of soils appeared to have only minor effects on total infiltration volumes due to the rapid transition from unsaturated to saturated flow conditions. Statistical analysis of the model results for the Grove St SGF showed that the unit-gradient model was the most accurate of the three models. Together, monitoring and modeling results confirm that subsurface gravel filters and other infiltration-type GSI could be more accurately sized to meet runoff reduction objectives if horizontal and vertical infiltration are accounted for by incorporating the unit-gradient model into system design techniques