Luke J. Marzen

An integrated approach for water quality assessment of a Kansas watershed

An integrated modeling process was used to estimate the nutrient loadings of different sub-watersheds of the Cheney Reservoir watershed, Kansas, USA. The Agricultural Nonpoint Source Pollution (AGNPS)-ARC INFO interface was used to extract input parameters from various Geographic Information System (GIS) layers, including a landcover layer prepared from Landsat TM image, for the AGNPS model during selected storm events. The curve numbers (CNs) were adjusted depending on the antecedent moisture condition (AMC) of the sub-watershed before each storm. The storm energy intensity (EI) values were computed using a probability method from a rainfall-EI relationship for the location of the study area. Several sensitive parameters of the AGNPS model were then calibrated to match the model-estimated total nitrogen (total-N) and total phosphorous (total-P) with the measured data on a sub-watershed basis during various runoff events. This process was validated by running the calibrated AGNPS model on each sub-watershed of the Cheney Reservoir watershed. This integrated modeling process was found to be effective for smaller watersheds that had adequate rainfall data.

A simple Landsat–MODIS fusion approach for monitoring seasonal evapotranspiration at 30 m spatial resolution

Persistent cloud-cover in the humid southeastern USA and the low temporal resolution of Landsat sensors limit the derivation of seasonal evapotranspiration (ET) maps at moderate spatial resolution. This article introduces a Landsat Moderate Resolution Imaging Spectroradiometer (Landsat–MODIS) ET fusion model that uses simple linear regression to integrate Landsat-derived reference ET fraction (ETrF) from mapping ET at high resolution with internalized calibration (METRIC) model and the vegetation temperature condition index (VTCI) derived from MODIS images. For a study site in Florida, model-estimated ET and ET estimated using energy budget eddy covariance at a US Geological Survey (USGS) station in Ferris Farm, Florida, were found to be in a good agreement with a root mean squared error of 0.44 mm day–1, coefficient of determination (R2) of 0.80, Nash–Sutcliffe efficiency of 0.79 for daily ET (ETd), and 2% relative error for cumulative seasonal ET during the growing season of 2001. At another study site in Alabama, the model underestimated 2008 annual water balance ET for the Fish River Watershed by 39 mm or 4%. Comparisons of model-estimated ET with that obtained using a non-fusion Landsat-only approach at both sites indicated that the fusion of Landsat and MODIS ET values reduces potential errors in ET estimation that would otherwise arise due to insufficient availability of cloud-free Landsat images for METRIC processing. Validation results and application of the model in deriving seasonal/annual ET for different land-cover classes in the Fish River Watershed suggested that the fusion model has the potential to be used in continuously monitoring ET for field- to watershed-level agricultural and hydrological applications in the southeastern USA.

Assessment of Economic and Water Quality Impacts of Land Use Change Using a Simple Bioeconomic Model

The objective of this study is to assess the economic and water quality impact of land use change in a small watershed in the Wiregrass region of Alabama. The study compares changes in water quality and revenue from agricultural and timber production due to changes in land use between years 1992 and 2001. The study was completed in two stages. In the first stage, a biophysical model was used to estimate the effect of land use change on nitrogen and phosphorus runoff and sediment deposition in the main channel; in the second stage, farm enterprise budgeting tools were used to estimate the economic returns for the changes in land use condition. Both biophysical and economic results are discussed, and a case for complex optimization to develop a decision support system is presented.

Applying Public Participation Geographic Information Systems to Wildlife Management

Wildlife management increasingly incorporates public participation to be more inclusive and reduce tensions between management and the general public in the decision-making process. There is also a need, however, to include spatial data since most wildlife biological and biophysical data are stored spatially in geographic information systems (GIS). This article presents a method for integrating this information using public participation geographic information systems (PPGIS). We asked stakeholders to identify specific places on a map that they would like to see maintained for the conservation of particular threatened species. This information is useful for identifying public wildlife management preferences and for allowing comparisons between public and expert opinions. We found high levels of public accuracy in identifying suitable habitat for threatened species conservation. We also identified places of potential conflict due to incompatible stakeholder preferences, but found little conflict between public conservation and development preferences.

Validation of evaporation estimates from a modified surface energy balance algorithm for land (SEBAL) model in the south-eastern United States

A modified surface energy balance algorithm for land (SEBAL) model, which has been widely used in the western United States since its development in 1998, was validated in the humid south-eastern United States using daily and monthly evapotranspiration (ET) estimates. Sixteen Landsat 5 Thematic Mapper (TM) images from April 2000 to September 2006 were processed, and the results were compared with energy-budget eddy covariance (EBEC) ET estimates from four US Geological Survey (USGS) stations. The model performed well in terms of Nash–Sutcliffe efficiency (NSE) coefficients (daily = 0.82, monthly = 0.77) and coefficients of determination (R 2, daily = 0.83, monthly = 0.77). Root mean square errors (RMSEs, daily = 0.48 mm/day, monthly = 16 mm/month), mean absolute errors (MAEs, daily = 0.32 ± 0.36 mm/day, monthly = 12 ± 10 mm/month), mean relative errors (MREs, daily = 7 ± 8%, monthly = 11 ± 12%) and mean bias errors (MBEs, daily = 0.05 mm/day, monthly = −2 mm/month) were comparable to the results from similar studies in the western United States. Results from the study support the applicability of the modified SEBAL model in the rapidly growing south-eastern United States as a tool for estimating consumptive water use via remotely sensed methods.

A comparison of carbon and nitrogen stocks among land uses/covers in coastal Florida

Coastal areas are rapidly developing due to population growth and the appeal of coastlines. In order to gain insight into how land use/cover affects carbon (C) storage in a coastal context, we examined soil and vegetation C and soil nitrogen (N) across land uses near Apalachicola, FL. Forested wetlands had the greatest soil C and N storage, while natural pine forests and pine plantations had the least. In paired plots, urban lawns had significantly greater mineral soil N content compared to urban forest remnants. Total ecosystem C (soil + vegetation) was higher in forested wetlands than all other land uses/covers combined due to the high organic content of those wetland soils. Urban forest remnants and lawns had greater total ecosystem C than natural pine forests and pine plantations, which likely reflects the differential influence of prescribed fire and less frequent anthropogenic disturbances between the rural and urban areas, respectively. Projections of land use change in Franklin County, FL combined with these data suggest that increases in C storage are possible with continued urbanization along the Gulf Coast, if forest remnants are left and lawns are incorporated in built-up areas. However, this study does not account for C emissions during land conversion, or any emissions associated with maintaining urban built-up and residential areas. A better understanding of land use/cover influences on C pools has applications for planning and development, as well as ecological and environmental protection in the region.

Projecting terrestrial carbon sequestration of the southeastern United States in the 21st century

How terrestrial ecosystems respond to future environmental change in the 21st century is critically important for understanding the feedbacks of terrestrial ecosystems to global climate change. The southeastern United States (SEUS) has been one of the major regions acting as a carbon sink over the past century; yet it is unclear how its terrestrial ecosystems will respond to global environmental change in the 21st century. Applying a process-based ecosystem model (Dynamic Land Ecosystem Model, DLEM) in combination with three projected climate change scenarios (A1B, A2, and B1 from the IPCC report) and changes in atmospheric carbon dioxide, nitrogen deposition, and ozone pollution, we examined the potential changes of carbon storage and fluxes in the terrestrial ecosystems across the SEUS during 2000–2099. Simulation results indicate that SEUSs terrestrial ecosystems will likely continue to sequester carbon in the 21st century, resulting in an increase in total carbon density (i.e., litter, vegetation biomass and soil carbon) from 13.5 kg C/m2 in the 2000s to 16.8 kg C/m2 in the 2090s. The terrestrial gross primary production and net primary production will probably continuously increase, while the net carbon exchange (positive indicates sink and negative indicates source) will slightly decrease. The carbon sequestration is primarily attributed to elevated atmospheric carbon dioxide and nitrogen deposition. Forests, including both deciduous and evergreen, show the largest increase in carbon storage as compared with other biomes, while cropland carbon storage shows a small decrease. The sequestered carbon will be primarily stored in vegetation for deciduous forest and in soil for evergreen forest. The central and eastern SEUS will sequester more carbon, while the western portion of the SEUS will release carbon to the atmosphere. The combined effects of climate and atmospheric changes on carbon fluxes and storage vary among climate models and climate scenarios. The largest increase in carbon storage would occur under the A1B climate scenario simulated by the NCAR climate model. Generally, the A1B scenario would result in more carbon sequestration than A2 and B1 scenarios; and the projected climate condition by the NCAR model would result in more carbon sequestration than other climate models.

Implications of management strategies and vegetation change in the Mount St. Helens blast zone

The 1980 eruptions of Mount St. Helens provided an excellent opportunity for scientists to investigate the recovery of vegetation communities following a major geologic disturbance. An important and often overlooked aspect in these studies is the human factor in recovery processes, and specifically, the different management approaches taken towards re-establishment of vegetation on lands under the control of various owners. This study examines vegetation changes throughout the 1980 blast zone using a time series of Landsat-derived Normalized Difference Vegetation Index (NDVI) images and change detection methods to assess the changes over 25 years, from 1980 to 2005, as a function of human management combined with ecological factors. This long-term tracking of change indicates that differences in the speed of vegetation re-establishment and consequent rates of change substantially reflect human involvement and varying management strategies.

Effect of Cell Size on AGNPS Predictions

This paper presents a study of Agricultural NonPoint Source Pollution (AGNPS) model using different cell sizes of 4-ha, 16-ha, 65-ha, and 260-ha with geomorphic calculation to study the effects of cell sizes on the predicted results. Red Rock Creek watershed of Kansas has been selected for running different sized storms of 0.05-, 0.5-, 1-, 2-, 20-, and 200-year storms. This study incorporated remotely sensed Landsat TM image to obtain landcover and different C-factors based on rangeland quantity and residue cover on cropland. AGNPS model input parameters were extracted from different GIS layers using the AGNPS-ARC/INFO interface. Five cells of 260-ha sizes were randomly selected for comparing the different average AGNPS parameters computed with each cell size. The peak flow rate, sediment yield, and nutrients outputs observed at the outlet of the watershed were found to decrease with cell size from 4-ha to 16-ha and then increase with the cell size. The flow path length computed by AGNPS decreased with the cell size.

Horizontal Accuracy Assessment of Global Positioning System Data from Common Smartphones

Smartphones have become ever-present in our lives since the launch of the Apple iPhone in 2007. Since then, the number of smartphones in use has climbed to over 1 billion worldwide. Many users are attracted to the myriad of apps that these devices offer, including location-based services (LBS) that allow users to track their current location. In this study we seek to establish some preliminary results concerning the horizontal accuracy of several common smartphones. Many of the devices used in this study represent several generations of the same device with developmental and technological upgrades differentiating them from one another. Location coordinate data were collected using volunteer students and their smartphones in the study and compared to RTK corrected benchmarks to assess horizontal accuracy. Each benchmark represented different types of local obstruction that have plagued traditional Global Positioning System (GPS) receivers for years. The objective is to create some preliminary results of smartphone LBS accuracies that can be used as a baseline in future studies.