Mariano Hernandez

KINEROS2-AGWA: Model Use, Calibration, and Validation

KINEROS (KINematic runoff and EROSion) originated in the 1960s as a distributed event-based model that conceptualizes a watershed as a cascade of overland flow model elements that flow into trapezoidal channel model elements. KINEROS was one of the first widely available watershed models that interactively coupled a finite difference approximation of the kinematic overland flow equations to a physically based infiltration model. Development and improvement of KINEROS continued from the 1960s on a variety of projects for a range of purposes, which has resulted in a suite of KINEROS-based modeling tools. This article focuses on KINEROS2 (K2), a spatially distributed, event-based watershed rainfall-runoff and erosion model, and the companion ArcGIS-based Automated Geospatial Watershed Assessment (AGWA) tool. AGWA automates the time-consuming tasks of watershed delineation into distributed model elements and initial parameterization of these elements using commonly available, national GIS data layers. A variety of approaches have been used to calibrate and validate K2 successfully across a relatively broad range of applications (e.g., urbanization, pre- and post-fire, hillslope erosion, erosion from roads, runoff and recharge, and manure transport). The case studies presented in this article (1) compare lumped to stepwise calibration and validation of runoff and sediment at plot, hillslope, and small watershed scales; and (2) demonstrate an uncalibrated application to address relative change in watershed response to wildfire.

A remote sensing approach for estimating distributed daily net carbon dioxide flux in semiarid grasslands

[1] Semiarid systems compose a significant portion of the world’s terrestrial area and may play an important role in the global carbon cycle. A model was developed using the relation between surface reflectance and temperature obtained from satellite imagery to determine a Water Deficit Index (WDI) that estimated distributed plant transpiration, and by extension carbon dioxide (CO2) flux, for a point in time. Relationships were developed to scale these instantaneous flux measurements up to daytime estimates, which were then used to obtain measures of nighttime flux. Satellite images were acquired for a 5-year period (1996–2000) during which transpiration and net CO2 flux were measured for a semiarid grassland site in southeastern Arizona. Manual and automatic chamber data were also collected at the same site during the monsoon growing seasons of 2005 and 2006 and used to develop the relationship between and daytime and nighttime CO2 flux. Strong linear relationships were found between WDI-derived instantaneous and daytime net CO2 flux estimates (R 2 = 0.97), and between daytime and nighttime fluxes (R 2 = 0.88). These relations were used to generate maps of distributed total daily net CO2 flux. The error for the model was within the range of error inherent in the data sets used to create it and remained reasonable when used with WDI values less than 0.9. This study demonstrated that remote sensing can offer a physically based means of obtaining daily net CO2 flux in semiarid grasslands.

The AGWA - KINEROS2 Suite of Modeling Tools

KINEROS originated in the 1970’s as a distributed event-based rainfall-runoff erosion model. A unique feature at that time was its interactive coupling of a finite difference approximation of the kinematic overland flow equations to the Smith-Parlange infiltration model. Development and improvement of KINEROS has continued for a variety of projects and purposes. As a result, a suite of KINEROS2-based modeling tools has been developed that can be executed from a single shell. The tools range from the event-based KINEROS2 flash-flood forecasting tool to the continuous KINEROS2-Opus2 (K2-O2) biogeochemistry tool. The KINEROS2 flash flood forecasting tool is being tested with the National Weather Service (NWS). It assimilates the NWS Digital Hybrid Reflectivity (DHR) radar product in near-real time and can simultaneously run ensembles using multiple radar-reflectivity relationships. In addition to simulation of runoff and sediment transport, K2-O2 can simulate common agricultural management practices, plant growth, nutrient cycling (nitrogen, phosphorus and carbon), water quality and chemical runoff. Like any detailed, distributed watershed modeling software, the KINEROS2 suite of tools often requires considerable effort to implement; it is necessary to delineate watersheds, discretize them into modeling elements, and parameterize these elements. This need motivated the development of the Automated Geospatial Watershed Assessment (AGWA) tool. This ArcGIS-based tool uses commonly available, national GIS data layers to fully parameterize, execute, and visualize results from both the SWAT and KINEROS2 models. By employing these two models AGWA can conduct hydrologic modeling and watershed assessments at multiple temporal and spatial scales. A variety of new capabilities have been added to AGWA to configure KINEROS2 inputs to simulate a number of land-management practices or changes (fire, urbanization, and best management practices) as well as incorporate decision-management tools for rangelands. An overview of these tools will be provided.