Spatiotemporal Flood Risk Determination and Management for a Large River Basin

The Chao Phraya River Basin (CPRB) of Thailand faces flooding almost every year. The severest flood occurred in the CPRB in 2011 with the highest property damage costs (46.5 billion USD) and the highest casualty (813 deaths). The objectives of this study were thus to (1) determine flood risk indices and categorize them into four risk zones (low, moderate, high, and very high) across 994 sub-districts in the CPRB during the six rainy months (May–October); and (2) propose specific measures for flood risk management for each of the categorized risk zones. The flood risk indices were assessed as the product of two hazard variables (flood levels and monthly cumulative precipitation) and the vulnerability variable (land uses). The findings revealed spatiotemporal variations in flood risk. Spatially, the sub-districts deemed to be in the high or very high flood risk zone were mainly located close to the Chao Phraya River (CPR), where the flood levels reached 1.1 – 4 m in depth; whereas the sub-districts detected in the low or moderate flood risk zone were located further away from the CPR. Temporally, more sub-districts were detected in the high or very high risk zone in September when heavy rainfalls were observed. Specific measures are proposed herein to manage flood risk regarding the categorized zones during three periods. The preventive and mitigation measures should be prepared before flooding; emergency responses should be practically implemented during flooding; and the recovery after flooding should cover both infrastructural and environmental damage and mental/physical illnesses amongst the affected people. Intensive measures are recommended for the sub-districts located in both the high and very high risk zones. These measures may be properly loosened for the sub-districts located in the low and moderate risk zones

Integrated Ecosystem Assessment: Lake Ontario Water Management

BACKGROUND: Ecosystem management requires organizing, synthesizing, and projecting information at a large scale while simultaneously addressing public interests, dynamic ecological properties, and a continuum of physicochemical conditions. We compared the impacts of seven water level management plans for Lake Ontario on a set of environmental attributes of public relevance. METHODOLOGY AND FINDINGS: Our assessment method was developed with a set of established impact assessment tools (checklists, classifications, matrices, simulations, representative taxa, and performance relations) and the concept of archetypal geomorphic shoreline classes. We considered each environmental attribute and shoreline class in its typical and essential form and predicted how water level change would interact with defining properties. The analysis indicated that about half the shoreline of Lake Ontario is potentially sensitive to water level change with a small portion being highly sensitive. The current water management plan may be best for maintaining the environmental resources. In contrast, a natural water regime plan designed for greatest environmental benefits most often had adverse impacts, impacted most shoreline classes, and the largest portion of the lake coast. Plans that balanced multiple objectives and avoided hydrologic extremes were found to be similar relative to the environment, low on adverse impacts, and had many minor impacts across many shoreline classes. SIGNIFICANCE: The Lake Ontario ecosystem assessment provided information that can inform decisions about water management and the environment. No approach and set of methods will perfectly and unarguably accomplish integrated ecosystem assessment. For managing water levels in Lake Ontario, we found that there are no uniformly good and bad options for environmental conservation. The scientific challenge was selecting a set of tools and practices to present broad, relevant, unbiased, and accessible information to guide decision-making on a set of management options

Evaluating urban park ecosystem services and modeling improvement scenarios

Three ecosystem services of the 25 public parks in Bangkok, including carbon sequestration, avoided runoff, four air pollutant removals (CO, NO2, PM10, and PM2.5), and the relevant monetary values, were determined using i-Tree Eco software. Two modeling scenarios (MS) including MS1 (no greening improvement) and MS2 (improvement by increasing either green area or tree planting, or both in the parks) with tree annual mortality rates (AMR) of 1 and 3% were developed to forecast the parks' ecosystem services for 50 years after 2020 (2021–2071). The results revealed the synergistic interactions of the different tree planting specifications (MS1 and MS2) and tree mortality rates on the parks' ecosystem services. For MC2 with the assigned 1% AMR, the parks’ optimal ecosystem services were obtained and the average annual monetary value (0.55 million USD) of the total ecosystem services of the 25 parks over the 50-year forecast was 150% higher than that (0.22 million USD) in 2020. Based on MS1 and MS2, tree rotations should be conducted in the parks after 2057 and 2065, respectively, for the low tree AMR (≤1%) but not later than 2041 and 2043, respectively, for the higher tree AMR

ECOTONE PROPERTIES AND INFLUENCES ON FISH DISTRIBUTIONS ALONG HABITAT GRADIENTS OF COMPLEX AQUATIC SYSTEMS

Ecotone properties (formation and function) were studied in complex aquatic systems in New York State. Ecotone formations were detected on two embayment-stream gradients associated with Lake Ontario during June?August 2002, using abrupt changes in habitat variables and fish species compositions. The study was repeated at a finer scale along the second gradient during June?August 2004. Abrupt changes in the habitat variables (water depth, current velocity, substrates, and covers) and peak species turnover rate showed strong congruence at the same location on one gradient. The repeated study on the second gradient in the summer of 2004 confirmed the same ecotone orientation as that detected in the summer of 2002 and revealed the ecotone width covering the lentic-lotic transitions. The ecotone on the second gradient acted as a hard barrier for most of the fish species. Ecotone properties were determined along the Hudson River estuary gradient during 1974?2001 using the same methods employed in the freshwater system. The Hudson ecotones showed both changes in location and structural formation over time. Influences of tide, freshwater flow, salinity, dissolved oxygen, and water temperature tended to govern ecotone properties. One ecotone detected in the lower-middle gradient portion appeared to be the optimal zone for fish assemblages, but the other ecotones acted as barriers for most fish species. A spatially explicit abundance exchange model (AEM) was developed to predict distribution patterns of five fish species in relation to their population characteristics and habitat preferences across the lentic-lotic ecotones on the two freshwater gradients associated with Lake Ontario. Preference indexes of each target fish species for water depth, water temperature, current velocity, cover types, and bottom substrates were estimated from field observations, and these were used to compute fish habitat preference (HP). Fish HP was a key variable in the AEM to quantify abundance exchange of an associated fish species among habitats on each study gradient. The AEM efficiently determined local distribution ranges of the fish species on one gradient. Results from the model validation showed that the AEM was able to quantify most of the fish species distributions on the second gradient.-The Royal Thai Government -The Lake Ontario Biocomplexity Project (Natural Science Foundation OCE?0083625) -The Hudson River Foundation (GF/01/05) -College of Agriculture and Life Sciences, Cornell Universit

Matrix of environmental attributes and shoreline classes.

<p>Check marks indicate significant impacts were expected; empty cells indicate that no significant effect was anticipated for the range of water level changes being considered.</p

Seven Lake Ontario water management plans defined by the Lake Ontario-St. Lawrence River Study Board [9].

<p>Seven Lake Ontario water management plans defined by the Lake Ontario-St. Lawrence River Study Board <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003806#pone.0003806-Lake1" target="_blank">[9]</a>.</p

Relationships between Lake Ontario water level and environmental attributes.

<p>A) bank swallow nesting in bluff habitat, B) piping plover nest area on sand beaches, C) benthic invertebrate habitat along coarse beaches, D) rock bass habitat along coarse beaches, E) killdeer foraging and nesting area on coarse beaches. Relationships for both baymouth-barrier beach shorelines and protected wetland and backwater shoreline classes: F) area of submerged aquatic vegetation, G) area of emergent vegetation, and H) area of wetland vegetation. Baymouth-barrier beach shoreline relations included: I) suitability of habitat for Northern pike embryos and the earliest fry stages, J) nesting suitability for black tern, and K) nesting suitability for king rail. Relations only for the protected wetland and backwater shoreline classes were: L) suitability of habitat for bowfin early life stages, M) area of rainbow smelt adult staging and early life rearing habitat, N) nesting suitability for marsh wren, and O) suitability of habitat for overwintering beaver.</p

Environmental attributes for assessing impacts of water level regulation on Lake Ontario using management and public interests.

<p>Environmental attributes for assessing impacts of water level regulation on Lake Ontario using management and public interests.</p

Shoreline classes for assessing lake level effects throughout the Great Lakes.

<p>The classes were identified, characterized, and illustrated by Stewart and Pope <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003806#pone.0003806-Stewart1" target="_blank">[25]</a> and later refined and applied to all shoreline segments in the US and Canada. The percentage of the Lake Ontario shoreline composed of each class and its basic features relative to potential impacts are provided. Not included are artificial shorelines and other minor classes. Drawings included here were made from sketches in Stewart and Pope <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003806#pone.0003806-Stewart1" target="_blank">[25]</a>.</p