Predicting land cover using GIS, Bayesian and evolutionary algorithm methods

Modelling land cover change from existing land cover maps is a vital requirement for anyone wishing to understand how the landscape may change in the future. In order to test any land cover change model, existing data must be used. However, often it is not known which data should be applied to the problem, or whether relationships exist within and between complex datasets. Here we have developed and tested a model that applied evolutionary processes to Bayesian networks. The model was developed and tested on a dataset containing land cover information and environmental data, in order to show that decisions about which datasets should be used could be made automatically. Bayesian networks are amenable to evolutionary methods as they can be easily described using a binary string to which crossover and mutation operations can be applied. The method, developed to allow comparison with standard Bayesian network development software, was proved capable of carrying out a rapid and effective search of the space of possible networks in order to find an optimal or near-optimal solution for the selection of datasets that have causal links with one another. Comparison of land cover mapping in the North-East of Scotland was made with a commercial Bayesian software package, with the evolutionary method being shown to provide greater flexibility in its ability to adapt to incorporate/utilise available evidence/knowledge and develop effective and accurate network structures, at the cost of requiring additional computer programming skills. The dataset used to develop the models included GIS-based data taken from the Land Cover for Scotland 1988 (LCS88), Land Capability for Forestry (LCF), Land Capability for Agriculture (LCA), the soil map of Scotland and additional climatic variables.     

Assessment Tools for Urban Catchments: Defining Observable Biological Potential1

Abstract: Urbanization represents a strong and increasingly more prevalent impact on stream quality worldwide. One of the characteristic effects of increased urbanization is a consistent decline in biological stream condition. The characterization of this biological degradation with increasing urbanization presents a number of advantages for the study and management of urban streams and catchments. In this paper, the limitation of biological condition with urbanization, called observed biological potential, is characterized. Using an urban intensity index and a biological index developed specifically for urban systems in the Baltimore, Maryland; Cleveland, Ohio; and San Jose, California regions, two principal techniques were compared (quantile regression and bin regression) to define observed biological potential along urban gradients. Quantile regression was selected as the preferable tool for describing observed biological potential given the consistency with which it can be applied and its statistical efficiency, however, bin quantile regression performed similarly. Having identified a numeric approximation of observed biological potential, two methods for identifying factors related to distance from potential as a way of identifying critical environmental factors affecting biological condition in urban areas were explored. The results of this work can be used for identifying benchmarks for urban stream biological condition, identifying limiting catchment characteristics, and prioritizing urban stream management efforts.     

Development of a Quantitative Pasture Phosphorus Management Tool Using the SWAT Model1

Abstract: Assessment tools to evaluate phosphorus loss from agricultural lands allow conservation planners to evaluate the impact of management decisions on water quality. Available tools to predict phosphorus loss from agricultural fields are either: (1) qualitative indices with limited applicability to address offsite water quality standards, or (2) models which are prohibitively complex for application by most conservation planners. The purpose of this research was to develop a simple interface for a comprehensive hydrologic/water quality model to allow its usage by farmers and conservation planners. The Pasture Phosphorus Management (PPM) Calculator was developed to predict average annual phosphorus (P) losses from pastures under a variety of field conditions and management options. PPM Calculator is a vastly simplified interface for the Soil and Water Assessment Tool (SWAT) model that requires no knowledge of SWAT by the user. PPM Calculator was validated using 33 months of data on four pasture fields in northwestern Arkansas. This tool has been extensively applied in the Lake Eucha/Spavinaw Basin in northeastern Oklahoma and northwestern Arkansas. PPM Calculator allows conservation planners to take advantage of the predictive capacity of a comprehensive hydrologic water quality model typically reserved for use by hydrologists and engineers. This research demonstrates the applicability of existing water quality models in the development of user friendly P management tools.     

Return to the River: Environmental Flow Policy in the United States and Canada1

Abstract: This paper provides an overview and summary of United States and Canadian federal, state, and provincial laws that offer some form of legal protection for environmental flows. Special attention is given to the new “second generation” law established in Texas and to ways western states are beginning to encourage transactions that help restore dewatered streams. Progress in the eastern states and some Canadian provinces to provide environmental flow protection is addressed. Based on this review, this paper presents recommended elements of a “model” environmental flow policy.     

Constraints to Watershed Planning: Group Structure and Process1

Floress, Kristin, Jean C. Mangun, Mae A. Davenport, and Karl W.J. Williard, 2009. Constraints to Watershed Planning: Group Structure and Process. Journal of the American Water Resources Association (JAWRA) 45(6):1352‐1360. Abstract: The roles that agencies and other partners play in collaborative watershed management are not always clearly identified. Key factors contributing to group‐level outcomes in watershed groups include both structural and procedural elements. Structural elements include membership systems, project partners, and funding, while procedural elements include leadership, shared vision, and mission development. The current research reports on a case study conducted with a Midwestern watershed group that received Clean Water Act Section 319 funds to undertake a watershed planning process. Data come from focus groups, interviews, public comments, and meeting observation, and were analyzed using grounded theory. Findings of this study indicate that homogenous skill set, discord over group and partner roles, and failed problem identification contributed to the organizational inertia experienced by the watershed group. Implications of this research for groups receiving 319 funds are provided.     

Modeling the Hydrology of Climate Change in California’s Sierra Nevada for Subwatershed Scale Adaptation1

Young, Charles A., Marisa I. Escobar‐Arias, Martha Fernandes, Brian Joyce, Michael Kiparsky, Jeffrey F. Mount, Vishal K. Mehta, David Purkey, Joshua H. Viers, and David Yates, 2009. Modeling the Hydrology of Climate Change in California’s Sierra Nevada for Subwatershed Scale Adaptation. Journal of the American Water Resources Association (JAWRA) 45(6):1409‐1423. Abstract: The rainfall‐runoff model presented in this study represents the hydrology of 15 major watersheds of the Sierra Nevada in California as the backbone of a planning tool for water resources analysis including climate change studies. Our model implementation documents potential changes in hydrologic metrics such as snowpack and the initiation of snowmelt at a finer resolution than previous studies, in accordance with the needs of watershed‐level planning decisions. Calibration was performed with a sequence of steps focusing sequentially on parameters of land cover, snow accumulation and melt, and water capacity and hydraulic conductivity of soil horizons. An assessment of the calibrated streamflows using goodness of fit statistics indicate that the model robustly represents major features of weekly average flows of the historical 1980‐2001 time series. Runs of the model for climate warming scenarios with fixed increases of 2°C, 4°C, and 6°C for the spatial domain were used to analyze changes in snow accumulation and runoff timing. The results indicated a reduction in snowmelt volume that was largest in the 1,750‐2,750 m elevation range. In addition, the runoff center of mass shifted to earlier dates and this shift was non‐uniformly distributed throughout the Sierra Nevada. Because the hydrologic model presented here is nested within a water resources planning system, future research can focus on the management and adaptation of the water resources system in the context of climate change.     

The impact of urbanization on tropical mangroves (Fortaleza,Brazil): Evidence from PAH distribution in sediments

This investigation represents the first environmental diagnosis of the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments from a tropical mangrove in Fortaleza, northeastern Brazil. Sediment cores from six sampling stations in the Cocó and Ceará Rivers were retrieved in June-July 2006 to determine 17 priority PAHs. The total PAH concentrations (Σ_PAHs) ranged from 3.04 to 2234.76 μg kg^?1(Cocó River) and from 3.34 to 1859.21 μg kg^?1 (Ceará River). These levels are higher than those of other cities with more industrial development. PAH concentrations did not reach probable effect levels (PELs). However, from 4.5 to 87.5% of individual PAH concentrations can occasionally cause adverse biological effects for aquatic organisms. The PAH molecular ratios indicate that the PAHs in the sediment core were derived mainly from petroleum, wood, and charcoal combustion (pyrogenic source), and that atmospheric deposition and urban runoff may serve as important pathways for PAH input to the sediment. Clearly, the Σ_PAHs in sediments collected in the Cocó and Ceará Rivers indicate that ongoing pollution is more severe than past pollution.     

Impacts of experimental trampling on tall alpine herbfields and subalpine grasslands in the Australian Alps

The Australian Alps, which are of high conservation value, are popular summer bushwalking destinations. Experimental trampling trials using a standardized methodology were conducted to determine the resistance and resilience of the two common vegetation types: tall alpine herbfield and subalpine grasslands. Vegetation parameters were measured in lanes subject to control (no trampling), 30, 100, 200, 500 and 700 passes at five sites prior to trampling, immediately post trampling, 2 weeks, 6 weeks and 1 year post trampling. Vegetation height, cover of graminoids and herbs, as well as net species richness all declined with trampling, while litter cover increased. Thresholds for damage varied between the two communities and among the different vegetation parameters. The resistance indices for the two communities (number of passes resulting in 50% reduction in vegetation cover), however, were similar at around 440–450 passes indicating that these two communities are among the most resistant of the 19 alpine–subalpine communities that have been tested around the world, but only of moderate resistance compared to non-alpine communities. The two communities showed limited recovery with damage still evident 1 year post trampling. This indicates that they have only moderate tolerance to damage due to moderate resistance, but low resilience.     

Preliminary assessment of CO2 geological storage opportunities in Greece

This paper provides a preliminary assessment of the suitability of Tertiary sedimentary basins in Northern, Western and Eastern Greece in order to identify geological structures close to major CO₂ emission sources with the potential for long-term storage of CO₂. The term “emissions” refers to point source emissions as defined by the International Energy Agency, including power generation, the cement sector and other industrial processes. The Prinos oil field and saline aquifer, along with the saline formations of the Thessaloniki Basin and the Mesohellenic Trough have been identified as prospective CO₂ geological storage sites. In addition, a carbonate deep saline aquifer occurring at appropriate depths beneath the Neogene-Quaternary sediments of Ptolemais-Kozani graben (NW Greece) is considered. The proximity of this geological formation to Greece's largest lignite-fired power plants suggests that it would be worthwhile undertaking further site-specific studies to quantify its storage capacity and assess its structural integrity.     

Numerical simulations on the influence of matrix diffusion to carbon sequestration in double porosity fissured aquifers

The double porosity model for fissured rocks, such as limestones and dolomites, has some features that may be relevant for carbon sequestration. Numerical simulations were conducted to study the influence of matrix diffusion on the trapping mechanisms relevant for the long-term fate of CO₂ injected in fissured rocks. The simulations show that, due to molecular diffusion of CO₂ into the rock matrix, dissolution trapping and hydrodynamic trapping are more effective in double porosity aquifers than in an equivalent porous media. Mineral trapping, although assessed indirectly, is also probably more relevant in double porosity aquifers due to the larger contact surface and longer contact time between dissolved CO₂ and rock minerals. However, stratigraphic/structural trapping is less efficient in double porosity media, because at short times CO₂ is stored only in the fissures, requiring large aquifer volumes and increasing the risk associated to the occurrence of imperfections in the cap-rock through which leakage can occur. This increased risk is also a reality when considering storage in aquifers with a regional flow gradient, since the CO₂ free-phase will move faster due to the higher flow velocities in fissured media and discharge zones may be reached sooner.