Vegetation development in coastal foredunes in relation to methods of establishing marram grass ( Ammophila arenaria )

In coastal foredunes marram grass (Ammophila arenaria) is used to stabilize windblown sand. The development of traditionally plantedAmmophila into a more natural foredune vegetation may take 5–10 yr. For economic reasons, traditional planting may be replaced by alternative techniques such as planting seeds or disk-harrowing rhizome fragments. In this paper, we compare the initial vegetation development of traditionally planted stands with stands established from seeds and from rhizomes. The experiments were conducted on an artificial foredune originating from dredged sea sand. The total experimental area covered more than 100 ha and the vegetation development was studied for 6 yr. The data were analysed bya priori grouping of plant species according to their ecology, as well as by Principal Components Analysis (PCA) and Redundancy Analysis (RA) of the percentage ground cover per plant species. Comparing ecological groups of plants showed that all planting methods delivered equal numbers of plant species that are indicative for coastal dunes. PCA and RA showed that methods based on the use of rhizome material resulted in a higher percentage cover of clonal perennials (Calammophila baltica, Festuca rubra ssp.arenaria, Carex arenaria andCirsium arvense) than the traditionally planted stands and the stands obtained from seeds. The latter two were characterized by the dominance of annuals, bi-annuals and (mostly nonrhizomatous) perennials. Initially, the rates of succession were highest in the stands obtained from rhizomes. However, after 3–6 yr there were no differences between the various stands. During the first four years, the percentage cover by rhizomatous foredune plants developed faster than that of annuals, bi-annuals and perennials. After 6 yr, the latter contributed almost as much to the percentage cover as the clonal species.     

COPING WITH A SEVERE SUSTAINED DROUGHT ON THE COLORADO RWER: INTRODUCTION AND OVERVIEW1

ABSTRACT: In arid regions of rapid economic and population growth, adverse effects of droughts are likely to be increasingly serious. This article presents an introduction and overview of the papers collected in this special issue of the Water Resources Bulletin. The papers report on the second phase of a study of the impacts of and responses to a potential severe sustained drought in the Colorado River Basin in the southwestern U.S. The analyses were performed by a consortium of researchers from universities and the private sector located throughout the Basin. Tree ring studies suggest that droughts of duration and magnitude much more serious than any found in the modern records probably occurred in the Basin during earlier centuries. Taking the present-day configuration of the storage and diversion structures and the economic conditions in the Basin as the base-point, the general objectives of the study are three: first, to define a representative Severe Sustained Drought (SSD) and assess its hydrologic impacts; second, to forecast the economic, social and environmental impacts on the southwestern U.S.; and finally, to assess alternative institutional arrangements for coping with an SSD. The evaluation of impacts and policies was conducted with two distinct modeling approaches. One involved hydrologic-economic optimization modeling where water allocation institutions are decision variables. The second was a simulation-gaming approach which allowed “players” representing each basin state to interact in a real-time decision making mode in response to the unfolding drought.     

Developing sustainable agricultural systems for small farmers in Latin America

The great majority of farmers in Latin America are peasants who still farm small plots of land, usually in marginal environments utilizing traditional and subsistence methods. The contribution of the 16 million peasant units to regional food security is however substantial. Research has shown that peasant systems, which mostly rely on local resources and complex cropping patterns, are reasonably productive despite their small land endowments and low use of external inputs. Moreover analysis of NGO-led agroecological initiatives show that traditional crop and animal systems can be adapted to increase productivity by biologically re-structuring peasant farms which in turn leads to optimization of key agroecosystem processes (nutrient cycling, organic matter accumulation, biological pest regulation, etc.) and efficient use of labour and local resources. Examples of such grassroots projects are herein described to show that agroecological approaches can offer opportunities to substantially increase food production while preserving the natural resource base and empowering rural communities.     

Site search and multicriteria evaluation

Geographic information systems (GIS) are potentially powerful collections of tools which planners can use in the manipulation and analysis of spatial information. One traditional area of interest in this context is site search. Here, the functionality of GIS is, however, limited to certain deterministic analyses which serve merely as a computerised automation of the manual sieve mapping approach. The integration of multicriteria evaluation (MCE) techniques with GIS, is forwarded as a means of providing the user with the means to evaluate sites identified by sieve mapping techniques on the basis of multiple and conflicting criteria and objectives. An example application based on the search for suitable radioactive waste disposal sites in Britain using the Arc/Info GIS is included. The potential use of a combined GIS/MCE approach in the development of spatial decision support systems (SDSS) is considered.     

A new policy‐related measure of population dispersal and sparsity using GIS

Policy indicators applied at a national scale can have considerable financial impact for resource allocations to individual counties, especially if there are extreme local factors. This article develops arid explores a new measure of population dispersal and sparsity and discusses the impact of this indicator in a variety of locations, by using GIS techniques.     

COMPUTER ASSISTED NEGOTIATION OF MULTIOBJECTIVE WATER RESOURCES CONFLICTS1

ABSTRACT: Since the early 1970s, a large volume of literature has accumulated related to multiobjective water resources management problems. A relatively small portion of this specifically addresses the negotiation process required when there are multiple decision makers with conflicting objectives. This paper focuses on that process and describes a computer program designed to assist such negotiation processes. This interactive computer assisted negotiation support system is called ICANS. ICANS is designed for dynamic, multi-issue, multi-party negotiation problems. Based on information provided in confidence by each party via an interactive graphical interface, the program can help determine if there exist any possible alternatives that are equivalent or even preferred to each party's decision in the absence of a negotiated agreement. If such alternatives exist, through a series of iterations in which each party's input data, assumptions, and preferences may change, ICANS can assist the parties in their search for a mutually acceptable and preferred agreement. A simple example illustrates the data requirements and the use of ICANS in negotiation experiments.     

GEOGRAPHIC INFORMATION SYSTEMS AS A TOOL IN WATER USE DATA MANAGEMENT1

ABSTRACT: The temporal and locational attributes of water use data are ideally suited for analysis using a geographic information system (GIS) approach. A GIS combines spatial database management, statistical analysis, and cartographic modelling capabilities within a computer hardware and software configuration. Texas water use data for selected categories in 1980 and 1986 were analyzed using ARC/INFO to demonstrate the utility of GIS for water resource information management. Examples of data analysis and display are presented to illustrate the effectiveness of cartographic representations to communicate water use data.     

RED RIVER OF THE NORTH BASIN,MINNESOTA, NORTH DAKOTA,AND SOUTH DAKOTA1

ABSTRACT: The environmental setting of the Red River of the North basin within the United States is diverse in ways that could significantly control the areal distribution and flow of water and, therefore, the distribution and concentration of constituents that affect water quality. Continental glaciers shaped a landscape of very flat lake plains near the center of the basin, and gently rolling uplands, lakes, and wetlands along the basin margins. The fertile, black, fine-grained soils and landscape are conducive to agriculture. Productive cropland covers 66 percent of the land area. The principal crops are wheat, barley, soybeans, sunflowers, corn, and hay. Pasture, forests, open water, and wetlands comprise most of the remaining land area. About one-third of the 1990 population (511,000) lives in the cities of Fargo and Grand Forks, North Dakota and Moorhead, Minnesota. The climate of the Red River of the North basin is continental and ranges from dry subhumid in the western part of the basin to subhumid in the eastern part. From its origin, the Red River of the North meanders northward for 394 miles to the Canadian border, a path that is nearly double the straight-line distance. The Red River of the North normally receives over 75 percent of its annual flow from the eastern tributaries as a result of regional patterns of precipitation, evapotranspiration, soils, and topography. Most runoff occurs in spring and early summer as a result of rains falling on melting snow or heavy rains falling on saturated soils. Lakes, prairie potholes, and wetlands are abundant in most physiographic areas outside of the Red River Valley Lake Plain. Dams, drainage ditches, and wetlands alter the residence time of water, thereby affecting the amount of sediment, biota, and dissolved constituents carried by the water. Ground water available to wells, streams, and springs primarily comes from sand and gravel aquifers near land surface or buried within 100 to 300 feet of glacial drift that mantles the entire Red River of the North basin. Water moves through the system of bedrock and glacial-drift aquifers in a regional flow system generally toward the Red River of the North and in complex local flow systems controlled by local topography. Many of the bedrock and glacial-drift aquifers are hydraulically connected to streams in the region. The total water use in 1990, about 196 million gallons per day, was mostly for public supply and irrigation. Slightly more than one half of the water used comes from ground-water sources compared to surface-water sources. Most municipalities obtain their water from ground-water sources. However, the largest cities (Fargo, Grand Forks and Moorhead) obtain most of their water from the Red River of the North. The types and relative amounts of various habitats change among the five primary ecological regions within the Red River of the North basin. Headwater tributaries are more diverse and tend to be similar to middle-reach tributaries in character rather than the lower reaches of these tributaries for the Red River of the North. Concentrations of dissolved chemical constituents in surface waters are normally low during spring runoff and after thunderstorms. The Red River of the North generally has a dissolved-solids concentration less than 600 milligrams per liter with mean values ranging from 347 milligrams per liter near the headwaters to 406 milligrams per liter at the Canadian border near Emerson, Manitoba. Calcium and magnesium are the principal cations and bicarbonate is the principal anion along most of the reach of the Red River of the North. Dissolved-solids concentrations generally are lower in the eastern tributaries than in the tributaries draining the western part of the basin. At times of low flow, when water in streams is largely from ground-water seepage, the water quality more reflects the chemistry of the glacial-drift aquifer system. Ground water in the surficial aquifers commonly is a calcium bicarbonate type with dissolved-solids concentration generally between 300 and 700 milligrams per liter. As the ground water moves down gradient, dissolved-solids concentration increases, and magnesium and sulfate are predominant ions. Water in sedimentary bedrock aquifers is predominantly sodium and chloride and is characterized by dissolved-solids concentrations in excess of 1,000 milligrams per liter. Sediment erosion by wind and water can be increased by cultivation practices and by livestock that trample streambanks. Nitrate-nitrogen concentrations also can increase locally in surficial aquifers beneath cropland that is fertilized, particularly where irrigated. Nitrogen and phosphorous in surface runoff from cropland fertilizers and nitrogen from manure can contribute nutrients to lakes, reservoirs, and streams. Some of the more persistent pesticides, such as atrazine, have been detected in the Red River of the North. Few data are available to conclusively define the presence or absence of pesticides and their break-down products in Red River of the North basin aquifers or streams. Urban runoff and treated effluent from municipalities are discharged into streams. These point discharges contain some quantity of organic compounds from storm runoff, turf-applied pesticides, and trace metals. The largest releases of treated-municipal wastes are from the population centers along the Red River of the North and its larger tributaries. Sugar-beet refining, potato processing, poultry and meat packing, and milk, cheese, and cream processing are among the major food processes from which treated wastes are released to streams, mostly in or near the Red River of the North.     

MAXIMIZING THE VALUE OF INFORMATION FOR GROUND WATER PROTECTION: THREE TEST CASES1

ABSTRACT: Public awareness of the importance of protecting the nation's water supplies is growing. Recent studies have shown a substantial increase in the perceived value of protecting water supplies for future use. In the Northeast, much of the water supply comes from ground water. This paper examines three test cases, each with different approaches for using geographic information systems (GIS) for ground water protection planning. In Wellfleet, Massachusetts, build-out scenarios were used to support regulatory and land acquisition decisions for siting a public water supply well. In Hadley, Massachusetts, the focus was on a decision support model for septic suitability assessment in support of regulatory efforts and infrastructure expansion. For Cortland County, New York, an interactive graphic user interface was created to facilitate the manipulation and recombination of a large volume of data by county officials to target ground water pollution prevention efforts. As personal computers become more powerful and inexpensive, and GIS data become more readily available, community and county governments are turning to GIS as a tool for developing comprehensive resource protection plans. Once appropriate data are input, a GIS can effectively and efficiently be used to derive outcomes of various land use plans and regulations.