Showing papers on "Wetland classification published in 1999"

Wetland Indicators: A Guide to Wetland Identification, Delineation, Classification, and Mapping

Abstract: Wetland Definitions Wetland Concepts for Identification and Delineation Plant Indicators of Wetlands and Their Characteristics Vegetation Sampling and Analysis for Wetlands Soil Indicators of Wetlands Wetland Identification and Boundary Delineation Methods Problem Wetlands and Field Situations for Delineation Wetland Classification Wetlands of the United States: An Introduction, With Empahsis on Their Plant Communities Wetland Mapping and Photointerpretation Wetland Professionals, Environmental Engineers, Hydrologists, Soil Scientists Catalog no. L892, May 1999, c. 475 pp., ISBN: 1-87371-892-5, $49.95 NTI/Sales Copy Environmental scientists and others involved with wetland regulations can use Wetland Indicators to strengthen their knowledge about wetlands, and the use of various indicators, to support their decisions on difficult wetland determinations. Ralph W. Tiner primarily focuses on plants, soils, and other signs of wetland hydrology in the soil, or on the surface of wetlands in his discussion. Marketing Class Code: 8S, 8R4, 8H Shelving Guide Wetlands Category Wetlands Subcategory Environmental Engineering

Characterization of wetland hydrology using hydrogeomorphic classification

Abstract: Hydrologic data are essential for understanding relationships between wetland morphology and function and for characterizing landscape-scale patterns of wetland occurrence. We monitored water levels in 45 wetlands for three years to characterize the hydrology of wetlands in the vicinity of Portland, Oregon, USA and classified wetlands by hydrogeomorphic (HGM) class to determine whether hydrologic regimes differed in wetlands in different HGM classes. We also compared hydrologic regimes in naturally occurring wetlands (NOWs) and mitigation wetlands (MWs) and in wetlands with/without a human-made water-retention structure to determine whether and how human modifications are changing the hydrology of wetlands. We found no relationship between hydrologic attributes and land use, soil association, or wetland area. We did find significant differences related to presence of a water-retention structure and to wetland type (NOW or MW). Water levels were higher and had less temporal variability and more extensive inundation (as % wetland area) in MWs and in wetlands modified to include a retention structure. HGM class was very effective for characterizing wetland hydrology, with significant differences among, HGM classes for water level and for extent and duration of inundation. For three regional classes, we found the lowest water levels and lowest extent/duration of inundation in slope wetlands, intermediate conditions in riverine wetlands, and the highest water levels and greatest extent and duration of inundation in depressions. In “atypical” classes (Gwin et al. 1999), average water level and extent of inundation were similar to conditions in depressions, but the within-site variability in water levels in depressions-in-slope-setting and in-stream-depressions was significantly smaller than in the regional classes (p ≤ 0.001). Results highlight the importance of both geomorphic setting and wetland structure in defining wetland hydrology and support the use of HGM for wetland classification. Because hydrology is an important determinant of many wetland functions, resource managers using restoration and mitigation to offset wetland losses should strive for project design and siting that re-establish the hydrogeomorphology of natural wetlands to improve the likelihood of replacing wetland functions.

Estimating the ground-water contribution in wetlands using modeling and digital terrain analysis.

Abstract: Wetland classification and management often requires information on the contribution of ground water to a wetland’s water budget. Direct estimation of this parameter, however, is time-consuming, expensive, and can typically only be accomplished for small areas. Thus, a method to characterize ground-water flow in wetland areas and regions may be useful in many applications. The estimation technique described combines the use of a digital elevation model (DEM) with transient numerical modeling and assumes that the water table reflects the general pattern of surface topography. The DEM grid elevations are used as initial heads in the model. Stepwise ground-water drainage from the flow domain is simulated until a reasonable match is obtained between the observed and model water tables. By knowing or assuming hydraulic conductivity and using the model water-table configuration, an estimate for ground-water flow to and from each discretized grid node can be estimated from Darcy’s Law and the Dupuit approximation. The net result, when mapped, shows the simulated distribution of recharge and discharge within and surrounding the wetland. Two examples from the Shingobee River headwaters in central Minnesota indicate how the method may be used. Geologically recent development of glacial landforms has led to numerous lakes, ponds, and wetlands in the region. Using a 30-m, 1∶24,000 scale DEM grid in combination with data from the U.S. Fish and Wildlife National Wetlands Inventory, the model predicts the most likely areas of ground-water interaction in and near wetlands and lakes. More quantitative results can be obtained by applying observed water budget and soil/aquifer parameter data.

Conservation and Rehabilitation of Lake Kanyaboli Wetland, Kenya

Abstract: The Kenya national wetlands standing committee of the interministerial committee on environment defines wetlands as “Areas of land that are permanently, seasonally, or occasionally waterlogged with fresh, saline, brackish or marine waters, including both natural and man-made areas that support characteristic biota” (NWSC 1994). Although the Ramsar definition is broad enough, the national definition was deemed necessary to minimize confusion that often arose while using definitions developed in temperate countries. The three East African countries (Kenya, Uganda, and Tanzania) have come up with the region’ s wetland classification system (RWBG 1996). The classification identifies five broad wetland types that occur in East Africa as marine, estuarine, sodic and/or saline waters, freshwater, and man-made wetlands. Each of these broad types has several classes. In this classification system, Lake Kanyaboli is classified as a freshwater lacustrine/palustrine wetland. This is because it is a shallow lake adjoined to a wide palustrine wetland, the Yala swamp.

Survival of indicator microorganisms and enteric pathogens in wetlands

Abstract: 8 INTRODUCTION 10 Problem Definition 10 Literature Review 11 What is a Wetland ? 11 Natural and Constructed Wetlands 12 Wetland Classification 12 Natural Wetlands 12 Artificial or Constructed Wetlands 14 Wetland Plants 16 Wetland Indigenous Microbial Conmiunities 18 Pathogens in Domestic Wastewater 18 Bacteria 19