Urbanization as a limiter and catalyst of watershed-scale sediment transport: Insights from probabilistic connectivity modeling

The conversion of rural lands to urban areas exerts considerable influence on the hydrologic processes governing sediment transport at the watershed scale. While the effects of urbanization on hydrology have been well-studied, the corresponding impact to the spatial and temporal variability of sediment detachment, transport, and connectivity is less certain. To address this knowledge gap, we apply process-based hydrologic simulation, probabilistic connectivity modeling, and in situ turbidity sensing to five watersheds positioned along a steep land use gradient in Kansas, USA. Connectivity modeling results show that urbanization systematically decreases the maximal extent of watershed-scale connectivity on the wettest days of the study period, from 51 % in the most rural watershed to 28 % in the most urban watershed. On the other hand, urbanization focuses sediment transport into fewer, more frequently wetted pathways, such as roadway drainage networks, which are activated 3.5 times more frequently than the equivalent pathways in rural basins. In this way, urbanization limits maximal connectivity as impervious surfaces indefinitely disconnect source zones from the sediment cascade, but also catalyzes hot spots of connectivity as these same impervious areas generate excess runoff and channel it to drainage systems. The 23.9 ± 4.2 % of days that exhibit watershed-scale functional connectivity account for 85.0 ± 9.5 % of sediment export with most of the export tied to a few highly connected days. Sensing results show that increases in watershed-scale connectivity only translate to larger fluvial sediment loads after a connectivity threshold (the median connected day) has been exceeded, suggesting a transition from functional to structural connectivity control on sediment dynamics after sufficient wetting. This study highlights the role of land use impacts on the sources and mechanisms of sediment transport, which will be an important consideration for land managers as urban areas continue to expand to accommodate global migration patterns

Comparison of Two Hydrological Models, HEC-HMS and SWAT in Runoff Estimation: Application to Huai Bang Sai Tropical Watershed, Thailand

In the present study, the streamflow simulation capacities between the Soil and Water Assessment Tool (SWAT) and the Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS) were compared for the Huai Bang Sai (HBS) watershed in northeastern Thailand. During calibration (2007–2010) and validation (2011–2014), the SWAT model demonstrated a Coefficient of Determination (R2) and a Nash Sutcliffe Efficiency (NSE) of 0.83 and 0.82, and 0.78 and 0.77, respectively. During the same periods, the HEC-HMS model demonstrated values of 0.80 and 0.79, and 0.84 and 0.82. The exceedance probabilities at 10%, 40%, and 90% were 144.5, 14.5, and 0.9 mm in the flow duration curves (FDCs) obtained for observed flow. From the HEC-HMS and SWAT models, these indices yielded 109.0, 15.0, and 0.02 mm, and 123.5, 16.95, and 0.02 mm. These results inferred those high flows were captured well by the SWAT model, while medium flows were captured well by the HEC-HMS model. It is noteworthy that the low flows were accurately simulated by both models. Furthermore, dry and wet seasonal flows were simulated reasonably well by the SWAT model with slight under-predictions of 2.12% and 13.52% compared to the observed values. The HEC-HMS model under-predicted the dry and wet seasonal flows by 10.76% and 18.54% compared to observed flows. The results of the present study will provide valuable recommendations for the stakeholders of the HBS watershed to improve water usage policies. In addition, the present study will be helpful to select the most appropriate hydrologic model for humid tropical watersheds in Thailand and elsewhere in the world.Comparison of Two Hydrological Models, HEC-HMS and SWAT in Runoff Estimation: Application to Huai Bang Sai Tropical Watershed, ThailandpublishedVersio

Post-Westgate SWAT : C4ISTAR Architectural Framework for Autonomous Network Integrated Multifaceted Warfighting Solutions Version 1.0 : A Peer-Reviewed Monograph

Police SWAT teams and Military Special Forces face mounting pressure and challenges from adversaries that can only be resolved by way of ever more sophisticated inputs into tactical operations. Lethal Autonomy provides constrained military/security forces with a viable option, but only if implementation has got proper empirically supported foundations. Autonomous weapon systems can be designed and developed to conduct ground, air and naval operations. This monograph offers some insights into the challenges of developing legal, reliable and ethical forms of autonomous weapons, that address the gap between Police or Law Enforcement and Military operations that is growing exponentially small. National adversaries are today in many instances hybrid threats, that manifest criminal and military traits, these often require deployment of hybrid-capability autonomous weapons imbued with the capability to taken on both Military and/or Security objectives. The Westgate Terrorist Attack of 21st September 2013 in the Westlands suburb of Nairobi, Kenya is a very clear manifestation of the hybrid combat scenario that required military response and police investigations against a fighting cell of the Somalia based globally networked Al Shabaab terrorist group.Comment: 52 pages, 6 Figures, over 40 references, reviewed by a reade

Impacts of Landscape Change on Water Resources

Changes in land use and land cover can have many drivers, including population growth, urbanization, agriculture, demand for food, evolution of socio-economic structure, policy regulations, and climate variability. The impacts of these changes on water resources range from changes in water availability (due to changes in losses of water to evapotranspiration and recharge) to degradation of water quality (increased erosion, salinity, chemical loadings, and pathogens). The impacts are manifested through complex hydro-bio-geo-climate characteristics, which underscore the need for integrated scientific approaches to understand the impacts of landscape change on water resources. Several techniques, such as field studies, long-term monitoring, remote sensing technologies, and advanced modeling studies, have contributed to better understanding the modes and mechanisms by which landscape changes impact water resources. Such research studies can help unlock the complex interconnected influences of landscape on water resources in terms of quantity and quality at multiple spatial and temporal scales. In this Special Issue, we published a set of eight peer-reviewed articles elaborating on some of the specific topics of landscape changes and associated impacts on water resources

A GIS-Based Watershed Impact Management Model

Assessment of land use changes on hydrological processes is essential for the planning and development of sustainable land management practices and water resources. Understanding how land management practices influence hydrological components is essential for the prediction of hydrological consequences of changes in land use. Given the plethora of hydrological models, digital data sources, and the limited availability of observed data, it is difficult to quantify the impacts of land use changes on hydrology. In this study, a Watershed Impact Management (WIM) model framework was conceptualized. A case study of the Yocona River basin, Mississippi, was implemented with the soil and water assessment tool (swat) using the arcgis extension and interface. The objective of this study was to quantify the impacts of three different land use change scenarios. These scenarios were developed based on projected future land use planning for the city of Oxford and Lafayette County. Expanded urbanization in scenario was the strongest contributor to increased runoff and water yield. Incorporation of best management practices (BMPS) in scenario b resulted in a significant reduction of sediment yield and nutrient load. However, no changes were evident in groundwater nitrate loading despite the addition of BMPS. The replacement of all non-urban areas with forest trees in the Yocona river basin, (scenario c) resulted in decreased runoff and sediment yield. The WIM modeling approach in the quantification and assessment of impacts of land use change can be applied to all watersheds, even those with limited data availability and will provide quantitative information in planning and decision-making for land and water resource management

Effect of using multi-year land use land cover and monthly LAI inputs on the calibration of a distributed hydrologic Model

Effective management of water resources entails the understanding of spatiotemporal changes in hydrologic fluxes with variation in land use, especially with a growing trend of urbanization, agricultural lands and non-stationarity of climate. This study explores the use of satellite-based Land Use Land Cover (LULC) data while simultaneously correcting potential evapotranspiration (PET) input with Leaf Area Index (LAI) to increase the performance of a physically distributed hydrologic model. The mesoscale hydrologic model (mHM) was selected for this purpose due to its unique features. Since LAI input informs the model about vegetation dynamics, we incorporated the LAI based PET correction option together with multi-year LULC data. The Globcover land cover data was selected for the single land cover cases, and hybrid of CORINE (coordination of information on the environment) and MODIS (Moderate Resolution Imaging Spectroradiometer) land cover datasets were chosen for the cases with multiple land cover datasets. These two datasets complement each other since MODIS has no separate forest class but more frequent (yearly) observations than CORINE. Calibration period spans from 1990 to 2006 and corresponding NSE (Nash-Sutcliffe Efficiency) values varies between 0.23 and 0.42, while the validation period spans from 2007 to 2010 and corresponding NSE values are between 0.13 and 0.39. The results revealed that the best performance is obtained when multiple land cover datasets are provided to the model and LAI data is used to correct PET, instead of default aspect-based PET correction in mHM. This study suggests that to minimize errors due to parameter uncertainties in physically distributed hydrologic models, adequate information can be supplied to the model with care taken to avoid over-parameterizing the model.Erasmus Mundus Scholarship programinfo:eu-repo/semantics/publishedVersio

Design of a Metadata Framework for the Environmental Models with an Example Hydrologic Application in HydroShare

Environmental modelers rely on a variety of computational models to make predictions, test hypotheses, and address specific problems related to environmental science and natural resource management. Scientists and engineers must devote significant effort to preparing these computational models. While significant attention has been devoted to sharing and reusing environmental data, less attention has been devoted to sharing and reusing environmental models. A first step toward increasing environmental model sharing and reuse is to define a general metadata framework for models that is flexible and, therefore, applicable across the wide variety of models used by environmental modelers. This paper proposes a general approach for representing environmental model metadata that extends the Dublin Core metadata framework. The framework is implemented within the HydroShare system and applied for a hydrologic model sharing use case. This example application demonstrates how the metadata framework implemented within HydroShare can assist in model sharing, publication, reuse, and reproducibility

Advancing Cyberinfrastructure for Collaborative Data Sharing and Modeling in Hydrology

Hydrologic research is increasingly data and computationally intensive, and often involves hydrologic model simulation and collaboration among researchers. With the development of cyberinfrastructure, researchers are able to improve the efficiency, impact, and effectiveness of their research by utilizing online data sharing and hydrologic modeling functionality. However, further efforts are still in need to improve the capability of cyberinfrastructure to serve the hydrologic science community. This dissertation first presents the evaluation of a physically based snowmelt model as an alternative to a temperature index model to improve operational water supply forecasts in the Colorado River Basin. Then it presents the design of the functionality to share multidimensional space-time data in the HydroShare hydrologic information system. It then describes a web application developed to facilitate input preparation and model execution of a snowmelt model and the storage of these results in HydroShare. The snowmelt model evaluation provided use cases to evaluate the cyberinfrastructure elements developed. This research explored a new approach to advance operational water supply forecasts and provided potential solutions for the challenges associated with the design and implementation of cyberinfrastructure for hydrologic data sharing and modeling