Hydrological Simulation Program-Fortran Model Research Articles

BASINS/HSPF: Model Use, Calibration, and Validation

This article presents recommendations by model developers and the authors about calibration and validation procedures for the Hydrological Simulation Program - Fortran (HSPF) as applied through BASINS. HSPF is a continuous simulation watershed model that simulates nonpoint-source runoff and pollutant loadings for a watershed and performs flow and water quality routing in stream reaches and well-mixed lakes and impoundments. HSPF can be used to estimate nonpoint-source loads from various land uses as well as fate and transport processes in streams and lakes. This article describes the ideal calibration and validation process for the full range of constituents modeled by HSPF, as well as the process for acceptable minimum calibration and validation of this model. The model information and guidance provided in this article may be used to help in determining the scope of the proposed ASABE Standard/Engineering Practice for model calibration and validation. Model calibration and validation are necessary and critical steps in any model application. For HSPF and most other watershed models, calibration is an iterative procedure of parameter evaluation and refinement, as a result of comparing simulated and observed values of interest. Model validation is in reality an extension of the calibration process. Its purpose is to ensure that the calibrated model properly assesses all the variables and conditions that can affect model results, and to demonstrate the ability to predict field observations for periods separate from the calibration effort. For HSPF calibration and validation, a “weight of evidence” approach is most widely used in practice when models are examined and judged for acceptance for assessment and regulatory purposes. This article explores the “weight of evidence” approach and the current practice of watershed model calibration and validation based on more than 30 years of experience with HSPF. Example applications are described and model results are shown to demonstrate the graphical and statistical procedures used to assess model performance. In addition, quantitative criteria for various statistical measures are discussed as a basis for evaluating model results and documenting the model application efforts.

Predicting plausible impacts of sets of climate and land use change scenarios on water resources

Our world is changing at an unprecedented rate in terms of climate and land use, but these changes can affect our water resources. Hence, we need a methodology that can predict both their individual and agglomerative ramifications. Using the Little Miami River (LMR) watershed as a case study, this paper describes a spatial analytical approach integrating mathematical modeling and geographical information sciences to quantitatively examine the relative importance of the separate and combined hydrologic and water quality impacts of climate and land use changes. The Hydrologic Simulation Program – Fortran (HSPF) model was chosen in this study to simulate stream flow and nutrient transport process. Five hypothetical climate change scenarios were used to cover the possible ranges of variability in the year 2050. An enhanced population-coupled Markov-Cellular Automata (CA-Markov) land use model was developed to predict the 2050 land use pattern. When these scenarios were incorporated into the HSPF model, the future conditions in the LMR basin were postulated. The findings demonstrated that: 1) the LMR watershed would experience an increase in flow and nutrients under the 2050 land use projection, 2) stream flow and water quality impacts would be amplified when both climate and land use changes were simultaneously considered, 3) land use change (and in the case of the LMR watershed, urbanization) could help to alleviate water shortage during the dry years, 4) total phosphorus and nitrogen would increase under all future climate and land use scenarios; the highest increase was found under the combined wettest and future land use scenarios, and 5) the described approach is effective in simulating the hydrologic and water quality effects of climate and land use changes in a basin scale. These results are relevant to planners; they can be useful in formulating realistic watershed management policies and mitigation measures.

Multi-Objective Spatial Decision Model for Land Use Planning in a Tourism District of India

Although land-use change in the riparian corridor can be a viable option in mitigating nonpoint source pollution, its impacts under different geographical scales have yet to be ascertained. The goal of this research was to quantify the hydrologic impacts of land-use change in the riparian zones of a subwatershed through the use of an integrated modeling approach. The Hydrological Simulation Program-Fortran model was adopted to develop a hydrologic and water quality model for the Upper Little Miami River basin, a headwater subwatershed in Ohio, USA. After calibration and validation, the model was used to predict the hydrologic and water quality impacts under various scenarios of buffer zones. Results indicated that the 60 m, 90 m, and 120 m riparian forest and wetland buffers were able to reduce the mean annual flow by 0.26 to 0.28%, nitrite plus nitrate by 2.9 to 6.1%, and total phosphorus by 3.2 to 7.8%. Wilcoxon signed rank test for paired data revealed significant differences between the base case (no change in land-use pattern) and scenarios of forest or wetland buffer zones, between pairs of different buffer widths, and between pairs of forest and wetland buffers within a single width level. By integrating environmental information and systems analysis, this study has demonstrated that HSPF is an effective tool to model nonpoint source pollution from riparian land-use changes, even in a small subwatershed with relatively minimal anthropogenic influences. The findings from this research may be useful in facilitating the development of management solutions.

Using HSPF to Model the Hydrologic and Water Quality Impacts of Riparian Land-Use Change in a Small Watershed

Although land-use change in the riparian corridor can be a viable option in mitigating nonpoint source pollution, its impacts under different geographical scales have yet to be ascertained. The goal of this research was to quantify the hydrologic impacts of land-use change in the riparian zones of a subwatershed through the use of an integrated modeling approach. The Hydrological Simulation Program-Fortran model was adopted to develop a hydrologic and water quality model for the Upper Little Miami River basin, a headwater subwatershed in Ohio, USA. After calibration and validation, the model was used to predict the hydrologic and water quality impacts under various scenarios of buffer zones. Results indicated that the 60 m, 90 m, and 120 m riparian forest and wetland buffers were able to reduce the mean annual flow by 0.26 to 0.28%, nitrite plus nitrate by 2.9 to 6.1%, and total phosphorus by 3.2 to 7.8%. Wilcoxon signed rank test for paired data revealed significant differences between the base case (no change in land-use pattern) and scenarios of forest or wetland buffer zones, between pairs of different buffer widths, and between pairs of forest and wetland buffers within a single width level. By integrating environmental information and systems analysis, this study has demonstrated that HSPF is an effective tool to model nonpoint source pollution from riparian land-use changes, even in a small subwatershed with relatively minimal anthropogenic influences. The findings from this research may be useful in facilitating the development of management solutions.

The relative impacts of climate change and urbanization on the hydrological response of a Korean urban watershed

AbstractWe assessed the relative hydrological impacts of climate change and urbanization using an integrated approach that links the statistical downscaling model (SDSM), the Hydrological Simulation Program—Fortran (HSPF) and the impervious cover model (ICM). A case study of the Anyangcheon watershed, a representative urban region in Korea, illustrates how the proposed framework can be used to analyse the impacts of climate change and urbanization on water quantity and quality. The evaluation criteria were measurements of low flow (99, 95, and 90 percentile flow), high flow (10, 5, and 1 percentile value), pollutant concentration (30, 10, and 1 percentile value), and the numbers of days required to satisfy the target water quantity and quality for a sensitive comparison of subtle impacts of variations in these measures. Nine scenarios, including three climate scenarios (present conditions, A1B, and A2) and three land use change scenarios, were analysed using the HSPF model. The impacts of climate change on low flow (34·1–59·8% increase) and high flow (29·1–37·1% increase) were found to be much greater than those on the biochemical oxygen demand (BOD) (3·8–10·0% decrease). On the other hand, the impacts of urbanization on water quality (19·0–44·6% increase) are more significant than those on high (1·0–4·4% increase) and low flow (11·4–25·6% decrease). Furthermore, low flows are more sensitive to urbanization than high flows. The number of days required to satisfy the target water quantity and quality can be a sensitive criterion to compare the subtle impacts of climate and urbanization on human society, especially as they are much more sensitive than low flow and pollutant concentration. Finally, urbanization has a potent impact on BOD while climate change has a high impact on flow rate. Therefore, the impacts of both climate change and urbanization must be included in watershed management and water resources planning for sustainable development. Copyright © 2010 John Wiley & Sons, Ltd.

Analysis of Hydrological Processes Applying the HSPF Model in Selected Watersheds in Alabama, Mississippi, and Puerto Rico

The goal of this study was to evaluate the Hydrological Simulation Program FORTRAN (HSPF) to gain more insight in the underlying causes and mechanisms of hydrological processes in an upland basin in Alabama and Mississippi (1,856-km2 Luxapallila Creek), a humid subtropical watershed in coastal Alabama (140-km2 Fish River), and a steep-slope tropical catchment in Puerto Rico (99-km2 Rio Caonillas). For each watershed model, rainfall, potential evapotranspiration, and streamflow time series from January 1999 to December 2000 were used to calibrate model parameters and 2001 time series were applied to verify model results. In each study area, actual evapotranspiration was the main mechanism of water loss followed by river discharge. Annual baseflow values ranged from 58% of total discharge in Luxapallila Creek basin to 84% of total discharge in Fish River watershed. In Luxapallila Creek and Fish River, interflow was the primary mechanism of direct runoff; however, surface runoff was the main process of direct runoff in Rio Caonillas. The HSPF model was successfully adapted to model daily streamflow processes in Luxapallila Creek basin and Rio Caonillas catchment with coefficient of determination and Nash and Sutcliffe coefficient values between 0.61 and 0.71 for the entire period; however, the Fish River watershed model performance was poor. The poor performance is likely due to the lack of rainfall time series available within the watershed boundaries. In general, this study showed the robustness of the HSPF model in extreme environments (small catchments vs. large basins, flat vs. hilly areas, low vs. moderate/high runoff potential, tropical marine vs. humid subtropical climates).

Modeling Escherichia Coli and Its Sources in an Urban Bayou with Hydrologic Simulation Program—FORTRAN

Bacterial levels in Buffalo Bayou in Houston commonly exceed contact recreation standards. Potential sources of bacteria include wastewater treatment plants, sanitary sewer overflows, septic systems, wet and dry nonpoint-source discharges via direct runoff and pipes, direct deposition, and sediment. A water-quality model in the Hydrologic Simulation Program—FORTRAN (HSPF) was calibrated and validated for hydrology, sediment, and Escherichia coli and subsequently used to evaluate the impacts of the bacterial sources in the watershed. In addition, simple estimates of bacterial loads were calculated along with source evaluations from load duration curves. Load reductions based upon the simple estimates indicated that water-quality standards were met by reducing dry-weather indicator bacterial loads by 69% and wet-weather loads by 98%. When these load reductions were implemented in the HSPF model, however, standards were not met under dry-weather conditions. Residual nonpoint-source loading was found to cause the discrepancy between simple load estimate calculations and the developed water-quality model. This paper demonstrates that runoff can play a significant role in maintaining high levels of bacteria under all flow conditions and that understanding the temporal variations in bacterial source loading is critical to ensure that load reductions will achieve water-quality standards.

Analysis of uncertainty propagation through model parameters and structure

Estimation of uncertainty propagation in watershed models is challenging but useful to total maximum daily load (TMDL) calculations. This paper presents an effective approach, involving the combined application of Rosenblueth method and sensitivity analysis, to the determination of uncertainty propagation through the parameters and structure of the HSPF (Hydrologic Simulation Program-FORTRAN) model. The sensitivity analysis indicates that the temperature is a major forcing function in the DO-BOD balance and controls the overall dissolved oxygen concentration. The mean and standard deviation from the descriptive statistics of dissolved oxygen data obtained using the HSPF model are compared to those estimated using Rosenblueth's method. The difference is defined as the error propagated from water temperature through dissolved oxygen. The error propagation, while considering the second order sensitivity coefficient in Rosenblueth's method, is observed to have a mean of 0.281 mg/l and a standard deviation of 0.099 mg/l. A relative low error propagation value is attributed to low skewness of dependent and independent variables. The results provide new insights into the uncertainty propagation in the HSPF model commonly used for TMDL development.

Modeling of Nitrogen Retention in Amite River

This paper presents an efficient and effective modeling approach to estimation of nitrogen retention in streams and rivers. The approach involves an extension of a newly developed longitudinal solute transport model, variable residence time (VART), by incorporating a first-order nitrogen reaction term. Parameters involved in the VART model are estimated using monthly mean flow and water quality data obtained through both field measurements and watershed modeling using the Hydrologic Simulation Program Fortran model. It is found that there is a strong correlation between nitrate-nitrogen removal rate and water temperature. In addition, low nitrate-nitrogen concentrations commonly occur when total organic carbon (TOC) and dissolved oxygen (DO) are also low, and high nitrogen concentrations correspond to high DO and TOC, indicating that denitrification is the primary biogeochemical process controlling nitrogen removal in natural rivers. The new approach is demonstrated through the computation of nitrogen removal in the Amite River, LA, USA. Functional relationships between the nitrate-nitrogen removal rate and water temperature are established for the Amite River. Monthly mean nitrate-nitrogen concentrations along the river are computed using the extended VART model, and computed nitrogen concentrations fit observed ones very well. The estimated annual nitrate-nitrogen removal in the Amite River is 27.4 tons or 15.5% of total nitrate-nitrogen transported annually through the Amite River.

Applications of simulation technique on debris-flow hazard zone delineation: a case study in Hualien County, Taiwan

Abstract. Debris flows pose severe hazards to communities in mountainous areas, often resulting in the loss of life and property. Helping debris-flow-prone communities delineate potential hazard zones provides local authorities with useful information for developing emergency plans and disaster management policies. In 2003, the Soil and Water Conservation Bureau of Taiwan proposed an empirical model to delineate hazard zones for all creeks (1420 in total) with potential of debris flows and utilized the model to help establish a hazard prevention system. However, the model does not fully consider hydrologic and physiographical conditions for a given creek in simulation. The objective of this study is to propose new approaches that can improve hazard zone delineation accuracy and simulate hazard zones in response to different rainfall intensity. In this study, a two-dimensional commercial model FLO-2D, physically based and taking into account the momentum and energy conservation of flow, was used to simulate debris-flow inundated areas. Sensitivity analysis with the model was conducted to determine the main influence parameters which affect debris flow simulation. Results indicate that the roughness coefficient, yield stress and volumetric sediment concentration dominate the computed results. To improve accuracy of the model, the study examined the performance of the rainfall-runoff model of FLO-2D as compared with that of the HSPF (Hydrological Simulation Program Fortran) model, and then the proper values of the significant parameters were evaluated through the calibration process. Results reveal that the HSPF model has a better performance than the FLO-2D model at peak flow and flow recession period, and the volumetric sediment concentration and yield stress can be estimated by the channel slope. The validation of the model for simulating debris-flow hazard zones has been confirmed by a comparison of field evidence from historical debris-flow disaster data. The model can successfully replicate the influence zone of the debris-flow disaster event with an acceptable error and demonstrate a better result than the empirical model adopted by the Soil and Water Conservation Bureau of Taiwan.

Improving HSPF Modeling Accuracy from FTABLES: Case Study for the Illinois River Basin

An application of the Hydrologic Simulation Program–FORTRAN (HSPF) model was developed for the entire Illinois River basin. During the simulation period from 1985 to 1995, simulated monthly and annual flows correlated well with observed data. However, its performance for daily flows in the lower portion of the basin was not satisfactory because of the complicated hydraulic condition of the Illinois River. In order to compensate the weakness of HSPF for flow routing, we have coupled a calibrated hydraulic model, one-dimensional unsteady flow through a full network of open channels (UNET), to improve flow routing accuracy and the overall performance of the HSPF model. In this study we intended to test how HSPF modeling accuracy can be improved from modifying function tables (FTABLES). We proposed four alternative sets of FTABLES: three (Sets B, C, and D) were based on Manning’s equation and one (Set E) used the flow-stage relationship. Simulations from these four alternatives were compared to the default FTABLES (Set A) and the coupled HSPF-UNET model. A comparison showed that improving the estimation on hydraulic gradients from flood frequency analysis (Set B) or improving the computation of reach geometry from surveyed cross sections (Set C) could only improve model accuracy. However, much better modeling accuracy can be obtained by improving both reach geometry and hydraulic gradients (Set D). Using the stage-discharge relationships simulated from a hydraulic model (Set E) also provided better results. The proposed methods have been successfully applied to watershed modeling with HSPF in the Illinois River basin. This study demonstrated that better HSPF modeling accuracy can be achieved with minimum effort from representative channel geometries and hydraulic gradients.

기후변화 및 도시화에 따른 유황곡선 및 BOD 농도지속곡선 변화

본 연구는 기후변화와 토지이용 변화로 인한 물순환 영향을 분석하기 위해 통계학적 축소모형(SDSM), 연속유출모형인 HSPF 모형, 불투수면 모형을 결합하는 통합접근법을 제시하였다. 이러한 기법을 안양천 유역에 적용하여 치수, 이수, 수질관리 측면에서 기후변화와 토지이용변화에 대한 영향을 분석하였다. 평가 기준은 유황곡선과 오염물질 농도 지속곡선이며 기후변화 시나리오 3개 (현재, A1B, A2)와 토지이용변화 3개, 총 9개의 시나리오에 대해 HSPF 모형을 이용하여 분석하였다. 그 결과 기후변화는 유출량에 대한 영향력이 크고 토지이용변화는 농도 변화에 크게 영향을 미치는 것으로 나타났다. 따라서 지속가능한 유역관리, 수자원관리를 위해 도시화와 기후변화에 대한 영향을 동시에 고려하는 것이 바람직하다. This study developed an integrated approach to climate change and urbanization impact assessment by linking models of SDSM (statistical downscaling model), HSPF (hydrological simulation program?Fortran) and ICM (impervious cover model). A case study of the Anyangcheon watershed illustrated how the proposed framework can be used to analyze the impacts of climate change and urbanization in terms of flood control, water security and water quality. The evaluation criteria were the variations of flow and pollutant concentration duration curves. In this study, nine scenarios including three climate (present condition, A1B and A2) and three urbanization scenarios were analyzed using HSPF model. As a result, climate change is a large influence on the flowrate and the urbanization affects the pollutant concentration. Therefore, the impacts of both climate change and urbanization must be included into the watershed management and water resources planning for sustainable development.

기후변화 및 도시화를 고려한 수자원관리 대안의 효과 분석

본 연구에서는 도시화와 기후변화에 대한 미래시나리오를 구성하고 각각의 시나리오별로 수자원 관리 대안들에 대한 효과분석을 수행하였다. 기후변화 시나리오는 SDSM (Statiatical Downscaling Method) 모형을 이용하여 구축하였으며 도시화는 불투수면 모형(Impervious cover model, ICM)을 이용하였다. 안양천 유역에 대해 하수처리수 재이용, 저수지 재개발 대안들을 유황곡선(flow duration curve)과 BOD 농도지속곡선(concentration duration curve)의 변화측면에서 연속유출모형인 HSPF (Hydrological Simulation Program - Fortran) 모형을 이용하여 분석하였다. 그 결과, 시나리오별 하천 유출량에 대한 대안 효과의 차이가 고수량 (<TEX>$Q_{10},\;Q_5,\;Q_1$</TEX>)에 비해 저수량(<TEX>$Q_{99},\;Q_{95},\;Q_{90}$</TEX>)과, 수질오염(<TEX>$C_{30},\;C_{10},\;C_1$</TEX>) 측면에서 크게 나타남을 알 수 있다. 즉 도시화는 물 순환을 크게 악화시키나 대안의 적용이 이러한 현상을 크게 막아줌을 알 수 있다. 또한 목표 유지유량 및 목표 수질 만족일수는 도시화에 대해 매우 민감한 것으로 나타났다. 따라서 향후 수자원 관리 대안을 수립할 때 기후변화와 도시화에 대한 분석을 포함시키는 것이 바람직하다. This study derived the analysis results of alternatives for integrated watershed management under urbanization and climate change scenarios. Climate change and urbanization scenarios were obtained by using SDSM (Statistical Downscaling Method) model and ICM (Impervious Cover Model), respectively. Alternatives for the Anyangcheon watershed are reuse of wastewater treatment plant effluent, and redevelopment of existing reservoir. Flow and BOD concentration duration curves were derived by using HSPF (Hydrological Simulation Program - Fortran) model. As a result, low flow (<TEX>$Q_{99},\;Q_{95},\;Q_{90}$</TEX>) and BOD concentration (<TEX>$Q_{10},\;Q_5,\;Q_1$</TEX>) were very sensitive to the alternatives comparing to high flow(<TEX>$C_{30},\;C_{10},\;C_1$</TEX>). Although urbanization makes the hydrological cycle distorted, effective alternatives can reduce its damage. The numbers of days to satisfy the instreamflow requirements and target water quality were also sensitive to urbanization. This result showed that the climate change and urbanization should be considered in the water resources/watershed and environmental planning.

An integrated framework for the hydrologic simulation of a complex geomorphological river basin

Summary The purpose of this study was to simulate the surface and groundwater flow in a karstic river basin where flood phenomena appear from time to time. The Koiliaris River Basin is located east of the city of Chania on the island of Crete in Greece. This river basin has a complex hydrogeology that consists of temporary – ephemeral rivers (tributaries), high mountainous karstic areas, springs, downstream karstic areas and karstic channel parts. In order to simulate all of these processes, a combination of four models was employed. The four models used in the present study were: (a) a two-part Maillet karstic model, used to determine the spring discharge, (b) a GIS-based Energy Budget Snow Melt model, developed to simulate the snow melt rate and compute the snow melt flow that enters the karstic system of the high mountainous area, A matlab code developed in this work combines the previous two independent models, (c) an empirical karstic channel model, developed to simulate the flow in the downstream karstic part of the Koiliaris River Basin, and (d) the Hydrological Simulation Program – FORTRAN (HSPF) model was used to model the hydrology of the watershed. Besides the karstic model, developed in this work, a significant contribution is that for the computation of the snow melt rate the energy budget considers the topography of the area (using GIS) that is incorporated with seven important parameters: elevation, slope, curvature, aspect, illumination, land use, and radiation. The main steps of this study included calibration, validation and sensitivity analysis of the HSPF model. The simulated results are in a very good agreement with the observed field data.

Calibration of the HSPF model with a new coupled FTABLE generation method

The hydrological simulation program FORTRAN (HSPF) is a comprehensive watershed model designed to simulate water quantity and quality processes. It is used widely throughout the world. Calculating discharge from a stream reach by HSPF is based mainly on function tables (FTABLEs), which describe the relationship between surface area, stream stage, volume, and discharge. The traditional method of FTABLE generation (using general stream cross-sections and the Manning equation or other discharge relationships) can be time-consuming and inaccurate when there are limited calibration stations and survey data. Recent insights into generalized coupled stage/storage and stage/discharge relationships, however, offer the potential to improve both the speed and accuracy of compiling FTABLEs and thus HSPF models. This study tested the application of these insights in generating FTABLEs. The study domain included 18 gauging stations in a coastal plain environment on the Peace River watershed in West-Central Florida. In the calibration of this model, wetlands were treated as reaches in HSPF with storage-attenuation characteristics. Over the simulation period, the modeled daily flow and stage correlated well with observed data at all gauging stations along the Peace River. The Nash-Sutcliffe efficiency and correlation coefficient computed using observed and simulated daily flows were 0.90 and 0.91, respectively, at the Peace River outlet. Rigorous testing found that the new system for calibrating the FTABLEs improved the model predictive ability and efficiency. Uncertainty in un-calibrated station performance was also reduced. The model parameters obtained in this study could potentially serve as reference values for model application in similar climatic regions. They may also have particular relevance in disaster management, as the simulation period extended over the hurricane season of 2004, and the model domain was within a high hurricane impact zone. The possible effects of hurricanes on discharge are also briefly discussed.

Evaluation of the Advection Scheme in the HSPF Model

This paper studied the mass conservation and constancy-preserving conditions of the advection scheme in the Hydrological Simulation Program-Fortran (HSPF) model. Equations were derived to examine the conditions for achieving both mass conservation and constancy-preserving properties. Case studies of simulating conservative materials, water temperature, and dissolved oxygen were conducted to show the impacts of the advection scheme on model applications. The mass conservative condition of HSPF can only be achieved weakly even though the advection equation is written in a mass conserved format for the current advection scheme. The constancy-preserving condition is strongly violated due to the inconsistency with continuity. The advection scheme was modified by the writer to use one single weighting factor for solving both water routing and material advection. Unrealistic results are removed and mass conservation and constancy-preserving conditions are achieved with the modified advection scheme.

Application of HSPF to the Distributed Model Intercomparison Project: Case Study

The Hydrologic Simulation Program–Fortran (HSPF) model was used to simulate streamflow for the Distributed Model Intercomparison Project (DMIP). This research describes how to integrate a next generation radar, NEXRAD data set into HSPF model and how to generate hydrologic runoff associated with the inputs of the spatial rainfalls, and discusses the challenges of HSPF during automatic calibration processes. The model performance of simulated streamflows with calibration and without calibration was also evaluated to assess the sensitivity of final estimated parameters through calibration procedures to initial parameters derived from physical watershed configuration. An automatic calibration scheme was adopted to optimize objectives that the writer specified in terms of statistical measures. Parameter estimation, a model-independent parameter estimator, was used as an automatic calibration tool in the hydrologic calibration of HSPF. Overall, the calibrated simulations outperformed the uncalibrated simulatio...

Modeling Nonpoint Source Pollutant Losses from a Small Watershed Using HSPF Model

Hydrologic models play an important role in the assessment of nonpoint source (NPS) pollution, which is essential for the environmental management of water resources. The present study has been undertaken to evaluate the applicability of a physically based continuous time scale, hydrological, and water quality computer model—Hydrologic Simulation Program-Fortran (HSPF)—in simulating runoff and sediment associated NPS pollutant losses from a small mixed type (land under agriculture, shrubs and forest, rocks, grasses) watershed of the Damodar Valley Corporation, Hazaribagh, India. Water soluble NO3–N, NH4–N, and P were considered as pollutants and their concentrations in the runoff were measured at the outlet of the watershed, randomly for 15 dates during the monsoon season (June–October) of 2000 and 2001. The model calibration and validation results reveal that the seasonal trend of HSPF simulated runoff, sediment yield, and NPS pollutants compared reasonably with their measured counterparts. Although the concentrations of pollutants were generally overpredicted for NO3–N and underpredicted for NH4–N and water-soluble P in the month of June when fertilizers releasing NH4–N and P are applied in rice fields, the differences in the mean concentration were not significantly different at a 95% level of confidence. Variation in the simulated losses of water soluble N and P species between the years occurred largely due to differences in the amount and distribution of rainfall. These results indicate that the HSPF model can be used as a tool for simulating runoff and sediment associated NPS pollution losses from the study area.

Watershed Modeling of Copper Runoff to San Francisco Bay from Brake Pad Wear Debris

This watershed modeling effort was conducted as part of a larger study by the Brake Pad Partnership (BPP) that examines the potential impact of copper from brake pad wear debris (BPWD) released to the environment in the San Francisco Bay (SF) Region. The watershed model provides runoff loads to a Bay modeling effort to assess resulting concentrations in SF Bay. The U.S. EPA's Hydrological Simulation Program-FORTRAN (HSPF) model was set up for each of the 22 BPP modeled sub-watersheds that drain to the SF Bay. HSPF model runs were performed for each sub-watershed for the entire time period of water year 1981 through water year 2005. Model results were processed for flow, sediment, and copper loads; and annual and mean annual loads were tabulated. Uncertainty in both non-brake and brake release estimates was assessed by representing alternative scenarios of source loadings. Three cases of copper release scenarios were modeled -- with high, low, and median releases. Each of these three scenarios was modeled with and without releases from brake pads in order to determine the relative contribution of copper from brake pads in runoff to the Bay. The total anthropogenic contribution from brake pad wear debris towards total loads of copper to the Bay for the median estimate case varies from 15% to 57%. As expected, the brake pad contribution is much lower for the rural sub-watersheds than for the heavily urbanized subwatersheds, reflecting alternative human activity and traffic levels. Additional scenario runs were performed to assess the impacts of copper lost through the normal buildup/washoff attenuation algorithms and the time period for copper loads to return to background levels if all sources were eliminated. Scenario runs also considered impacts of climate changes such as wet and dry periods, and the relative impacts on loadings.

Estimation of pollutant loads considering dam operation in Han River Basin by BASINS/Hydrological Simulation Program-FORTRAN

Effective watershed management often demands qualitative and quantitative predictions of the effect of future management activities as arguments for policy makers and administration. The BASINS geographic information system was developed to compute total maximum daily loads, which are helpful to establish hydrological process and water quality modeling system. In this paper the BASINS toolkit HSPF model is applied in 20,271 km(2) large watershed of the Han River Basin is used for applicability of HSPF and BMPs scenarios. For proper evaluation of watershed and stream water quality, comprehensive estimation methods are necessary to assess large amounts of point source and nonpoint-source (NPS) pollution based on the total watershed area. In this study, The Hydrological Simulation Program-FORTRAN (HSPF) was estimated to simulate watershed pollutant loads containing dam operation and applied BMPs scenarios for control NPS pollution. The 8-day monitoring data (about three years) were used in the calibration and verification processes. Model performance was in the range of "very good" and "good" based on percent difference. The water-quality simulation results were encouraging for this large sizable watershed with dam operation practice and mixed land uses; HSPF proved adequate, and its application is recommended to simulate watershed processes and BMPs evaluation.