Ammarin Daranpob

Spatiotemporal pattern validation of chlorophyll-a concentrations in Lake Okeechobee, Florida, using a comparative MODIS image mining approach

A comparative analysis was conducted using three types of data-mining models produced from Moderate Resolution Imaging Spectroradiometer (MODIS) Terra Surface Reflectance 1-day or 8-day composite images to estimate chlorophyll-a (chl-a) concentrations in Lake Okeechobee, Florida. To understand the pros and cons of these three models, a genetic programming (GP) model was compared to an artificial neural network (ANN) model and multiple linear regression (MLR) model with respect to two different data sets related to model formulation. The first data set included the MODIS Terra bands from 1 to 7; the second data set extended the first data set by adding environmental parameters such as Secchi disc depth (SDD), total suspended solids (TSS), wind speed, water level, rainfall and air temperature collected around the lake in 2003 and 2004. The GP algorithm, which has an advantage in machine learning allowing us to select the appropriate input parameters that significantly impact the prediction accuracy, outperformed the other two models based on four statistical indices. Specifically, the GP modelling outputs revealed interesting determinations of chl-a concentrations for MODIS bands 3, 5, 6 and 7, corresponding to wavelengths 459–479, 1230–1250, 1628–1652 and 2105–2155 nm, respectively. The number of training data points is limited; therefore, the inclusion of additional environmental variables cannot improve the prediction accuracy of the GP-derived chl-a concentrations.

Comparative data mining analysis for information retrieval of MODIS images: monitoring lake turbidity changes at Lake Okeechobee, Florida

In the remote sensing field, a frequently recurring question is: Which computational intelligence or data mining algorithms are most suitable for the retrieval of essential information given that most natural systems exhibit very high non-linearity. Among potential candidates might be empirical regression, neural network model, support vector machine, genetic algorithm/genetic programming, analytical equation, etc. This paper compares three types of data mining techniques, including multiple non-linear regression, artificial neural networks, and genetic programming, for estimating multi-temporal turbidity changes following hurricane events at Lake Okeechobee, Florida. This retrospective analysis aims to identify how the major hurricanes impacted the water quality management in 2003-2004. The Moderate Resolution Imaging Spectroradiometer (MODIS) Terra 8-day composite imageries were used to retrieve the spatial patterns of turbidity distributions for comparison against the visual patterns discernible in the in-situ observations. By evaluating four statistical parameters, the genetic programming model was finally selected as the most suitable data mining tool for classification in which the MODIS band 1 image and wind speed were recognized as the major determinants by the model. The multi-temporal turbidity maps generated before and after the major hurricane events in 2003-2004 showed that turbidity levels were substantially higher after hurricane episodes. The spatial patterns of turbidity confirm that sediment-laden water travels to the shore where it reduces the intensity of the light necessary to submerged plants for photosynthesis. This reduction results in substantial loss of biomass during the post-hurricane period.

Assessing the long-term urban heat island in San Antonio, Texas based on moderate resolution imaging spectroradiometer/Aqua data

Urban environmental conditions are strongly dependent on the land use and land cover properties. Urban and rural areas normally exhibit obvious difference in land surface temperature (LST). The Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua (PM satellite) MYD11A1 temperature products (daily and 1 km spatial resolution) for the period from June 1 to September 30 between 2002 and 2008 were used to screen the existence of urban heat island (UHI) phenomena for the city of San Antonio, TX. 8-day MYD11A2 temperature products between 2002 and 2008 were also retrieved to map the temperature climatology at the 1:30 a.m. for the region. The UHI effect was detected in both satellite surface-temperature and meteorological station air-temperature record. The existence of an UHI of the San Antonio downtown area was clearly shown in about 90% of the available cloud-free (or cloudless) data from June 1-September 30 each year. It is especially prevalent in the night-time imagery due to less cloud contamination. During nighttime, the heat island (HI) is about 4 - 5 °K (6 - 8 °F) higher than the average temperature of the study area and 6 - 7 °K (8 - 12 °F) higher than the rural area. Surprisingly, the HI phenomenon is found not only in the downtown area, but also several other small areas in the northern corner. Finally, the long-term UHI effect of San Antonio and its relationship with normalized difference vegetation index (NDVI) were discussed. USGS rainfall data were also used to discuss the possible connections between the UHI and several local storm events.

Nutrient and Pathogen Removal with an Innovative Passive Underground Drainfield for On-site Wastewater Treatment

When urban regions gradually expand due to regional development, centralized sewage collection, treatment, and disposal is often unavailable for both geographic and economic reasons. As a consequence, about a quarter of the residences in the United States relied on decentralized treatment of wastewater. Household wastewater contains high concentration of nutrients (mainly nitrogen and phosphorus), disease-causing organisms and viruses, and some toxic chemicals. Nation wide, wastewater effluent from on-site wastewater treatment (OWTS) can represent a large fraction of nutrient loads to groundwater aquifers. Phosphorus and nitrogen compounds are the most frequent measurements to indicate nutrient loadings. Some aquifers may discharge into springs or other surface waters adversely affecting public health. Hence, on-site wastewater effluent disposal has contributed significant adverse impacts to the dynamics of the natural environment. Nowadays, due to widespread septic tank failure, scientists, engineers, and manufacturers in the wastewater treatment industry have developed a wide range of alternative passive technologies designed to address increasing hydraulic loads, energy saving requirement, and water contamination by nutrients and pathogens in OWTS. This paper aims to present an innovative design of the underground drainfield with soil amendments (sorption media) in a pilot septic tank system. The new system located at the OWTS test center, University of Central Florida (UCF) was tested and proved costeffective in the initial test run in fall 2008.

Heat island effect and urban storm events of San Antonio downtown area by MODIS/AQUA temperature sensor

Urban environmental conditions are strongly dependent on the land use and land cover properties and radiant thermal field of the land cover elements in the urban mosaic. Observations of urban reflectance and surface temperature provide valuable constraints on the physical properties that might be the determinants of urban storm formation. It is assume that consistencies in the covariation of land surface temperature with convective rainfall distribution can be identified to represent characteristics of the surface energy flux associated with different meteorological conditions. We retrieved the temperature from MODIS/Aqua (PM satellite) MYD11A1 temperature product (8-day composite and 1 km spatial resolution). Time period used is from June 1 to September 30 of year 2002 to 2008. MODIS reflectivity data and rainfall data corresponding to those dates were also used to verify the hypothesis. However, partial correlations may be seen in the time series analysis accounting for some convective storm events. Yet the San Antonio urban heat island (UHI) over the sea-breeze convergence zone along the coastal bend might affect the storm events too. Obviously, the other of the storm events were triggered by frontal cyclone at the continental scale that might not be directly related to the local UHI effects at all. Nevertheless, spatial analyses in relation to the NEXRAD images confirm spatial correlation between precipitation and UHI within at least 2 storm episodes.

Monitoring the algal bloom event in Lake Okeechobee, Florida under Tropical Cyclone Fay impacts using MODIS/Terra images

Lake Okeechobee, Florida is the largest freshwater lake in the southeastern U.S. It is a key component in the hydrologic system of South Florida providing water supply for agriculture, the environment, and urban areas. Excessive phosphorus loads, from the Okeechobee watershed over the last few decades have led to increased eutrophication of this lake. Much of the excess phosphorus has been sequestered into the sediments. Sediment water interactions, including diffusive fluxes and sediment resuspension are a source of available phosphorus for phytoplankton. As a consequence, nutrient-enriched lake water has led to phytoplankton blooms from time to time. These blooms are often quantified by measurement of chlorophyll-a concentrations. While the in-situ water quality monitoring is time-consuming, sporadic, and costly, multispectral remote sensing sensors onboard satellites can detect chlorophyll-a contained in most phytoplankton efficiently. The objective of this study is to demonstrate the use of MODIS/Terra Surface Reflectance 1- Day images to capture the unique algal bloom event one week after the landfall of the hurricane Fay in mid-Sept. 2008. Use of the genetic programming model permits sound information retrieval for spatial mapping of chlorophyll-a concentrations, which help explain the mechanism as to why the algal bloom event occurred.

Nutrient and pathogen removal in a passive on-site sewage treatment and disposal system (OSTDS) with a recirculation filtration tank.

Groundwater contamination due to the nutrients from a septic tank system is a vital concern in environmental health. Active OSTDS also know as on-site wastewater treatment is dependent on the use of pump to sustain the aerobic condition in the process and promote the nitrification which might not be sustainable in terms of energy saving. Experiments have been conducted over the past three years to find a cost-effective, passive on-site wastewater treatment process to improve nutrient removal. The inclusion of recirculation sand filter (RSF) might be a suitable intermediate process to trigger the proper nitrification/denitrification process between the septic tank and the drain field. This option may be adopted for these existing traditional septic tank systems as a retrofit project. Yet the science question as to how effectively the nitrification and denitrification can be fostered in an RSF remains unclear. Three types of medium: fine sand, course sand, and green sorption media (i.e. denoted as options 1, 2 & 3 in this study) were used to assess the performance of the RSF. In particular, phosphorus removal from the wastewater was one of the key concerns, and the capability of using limestone for phosphorus removal was also investigated and confirmed. It can be concluded that fine sand with limestone mixture had better performance for nutrient removal if clogging issue can be overcome by using a grinder pump when dosing. On average, the septic tank and RSF system with fine sand removal efficiencies were: 60.54% ammonium, 49.48% total Kjehldahl nitrogen (TKN), 42.57% total nitrogen (TN), 92.06% soluble reactive phosphorus (SRP) and 87.16% total phosphorus (TP). The E. Coli removal efficiency by RSF was 99.9% in all cases. However, the addition of green sorption media is not favored due to insufficient hydraulic residence time (HRT). If the size of the RSF can be increased, the use of green sorption media in combination with limestone might be beneficial. Keyword: Wastewater treatment, Nutrient removal, Real-time PCR, Environmental health

Using a Subsurface Upflow Wetland for Nutrient and Pathogen Removal in an On-site Sewage Treatment and Disposal System

The conventional decentralized sewage collection, treatment, and disposal systems are no longer able to fully respond to the needs of handling removal of nutrients.. Without proper sorption and nitrification/denitrification, a large fraction of nutrient loads such as nitrogen and phosphorus flowing into aquatic system may adversely affect the water quality and public health. Constructed wetland, a cost-effective small-scale wastewater treatment system with low energy and maintenance requirements and operational costs, may well fit the current needs. A subsurface constructed wetland system as designed as a performance-based passive on-site sewage treatment and disposal system (OSTDS) was proved effective after receiving septic wastewater flow. With the aid of a suite of locally adapted and selected plant species, such an OSTDS was configured to handle 189 cubic meters per day (50 GPD) influent using green sorption media at the test center located on the main campus of University of Central Florida (UCF). During the test run, results indicate that wetland 1, which was planted with Canna, achieved the best removal efficiency of 97.1 %, 98.3 %, 99.98 % and near 100.0 % for TN, TP, fecal coli and E.Coli, respectively. Keyword: Wastewater treatment, Nutrient control, Ecological engineering, Sustainability engineering, Green Technology, Environmental health

Comparative Study of Two Standard Septic Tank Drain Fields Using Different Sand with Recirculation for Nutrient Removal

On-site Wastewater Treatment System (OWTS) using a septic tank followed by a recirculating sand filter (RSF) with effluent discharged to an unlined standard drain field is a typical performance-based treatment facility for nutrient removal. The type of effluent distribution in the standard drain field systems include gravity systems, low pressure dosed systems, drip irrigation systems, etc. The standard drain field that is constructed by a series of parallel, underground, perforated pipes allows the septic tank effluent to percolate into the surrounding soil in the vadose (unsaturated) zone where most of the residual nutrients may be assimilated. The inclusion of RSF may improve the nitrification to some extent so as to promote denitrification in the drain field. With such design, most residual nutrients in wastewater are expected to be consumed as the wastewater passes through the soil. This author’s aim of this paper is to present the effectivenss of RSF and a comparative study with these two different drain field sands for nutrient removal in vadose zone. They include astatula sand (i.e., citrus grove sand) and washed building sand, popular in Central Florida for drain field use. The use of a gene identification method is novel in supporting the biological removal. Research findings show that the performance of washed building sand and the astatula sand in terms of ultimate nutrient removal is about the same. Because astatula sand is less costly it can possibly be considered for replacement of the more expensive washed building sand.