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Mapping near-surface soil moisture on regional scale using ERS-2 SAR data

Journal Articles & Books
Diciembre, 2003

Soil moisture is an important hydrologic variable of great consequence in both natural and agricultural ecosystems. Unfortunately, it is virtually impossible to accurately assess the spatial and temporal variability of surface soil moisture using conventional, point measurement techniques. Remote sensing has the potential to provide areal estimates of soil moisture at a variety of spatial scales. This investigation evaluates the use of European Remote Sensing Satellite (ERS-2) C-band, VV polarization, synthetic aperture radar data for regional estimates of surface soil moisture.

Ecological implications of Fulbe pastoralism in southwestern Nigeria

Journal Articles & Books
Diciembre, 2003
Nigeria

The study used a combination of ethno-social surveys and Geographical Information Systems (GIS) to assess 651 pastoral households and their land use under agropastoral production systems in Ogun State, Nigeria. Yields of arable crops on agropastoralists' fields were generally low. Livestock productivity was similar on all parameters to levels in comparable contexts elsewhere across the West African subregion, but generally below possible potentials and on-farm research findings. Pastoral households' activities presently influence between 221 km2 and 523 km2 of land in Ogun State.

Water, Sediment, Nutrient, and Pesticide Measurements in an Agricultural Watershed in Illinois During Storm Events

Journal Articles & Books
Diciembre, 2003

Flow and concentrations of suspended sediment, nitrate-N, phosphate-P, atrazine, and metolachlor were monitored during the spring seasons of 1998 and 1999, primarily during storm events, at a tributary station (Big Ditch) and two main-stem stations (Fisher and Mahomet) of the Upper Sangamon River watershed in east central Illinois. These three stations respectively drain 98, 622, and 932 km 2 of mainly agricultural lands. Rainfall data were collected from six newly established raingage stations.

Resource use conflicts: the future of the Kalahari ecosystem

Journal Articles & Books
Diciembre, 2003

The Kalahari ecosystem is characterized by natural resource conflicts and land-use pressure resulting from intensification of human activities. This paper addresses three issues of concern associated with the Kalahari ecosystem resource management: (i) the major land-use/land cover shifts in the Kalahari ecosystem since 1970 and the resulting pattern in vegetation species composition, cover and density; (ii) the possible explanations for the observed shifts; and (iii) the possible resource conflicts likely to arise.

Watershed-Scale AMC Selection for Hydrologic Modeling

Journal Articles & Books
Diciembre, 2003

The Natural Resources Conservation Service curve–number (CN) method commonly uses three discrete levels (1, 2, and 3) of antecedent moisture condition (AMC) to describe soil moisture at the time of a runoff event. However, this may not adequately represent soil water conditions for watershed modeling purposes. The objectives of this study were to evaluate the use of individual–event watershed–scale AMC values to adjust field–scale CN, and to assess which hydrologic parameters would provide the best estimate of individual–event AMC.

Forecasting the environmental and socio-economic consequences of changes in the Common Agricultural Policy

Journal Articles & Books
Diciembre, 2003

A framework is described that has been used to assess the effect of the European Commission's Agenda 2000 proposal on the Dumfries and Galloway region, Scotland. The model assesses the impact of agriculture on land-use patterns, the environment and socio-economics of the region. It incorporates a farm-type linear programming sub-model with environmental and socio-economic sub-models.

partial order approach for summarizing landscape quality

Journal Articles & Books
Diciembre, 2003

We propose a simple mathematical framework to define consistently the environmental quality of a given landscape based on the relative abundances of the constituting land cover classes. Unlike traditional diversity measures, the new method does not evaluate the simple dispersion of the relative abundances of land cover classes, but assigns a weight to each land cover class according to the rank along a gradient of environmental quality.

Accessibility as a determinant of landscape transformation in western Honduras: linking pattern and process

Journal Articles & Books
Diciembre, 2003
Honduras

This study evaluates the relationship between landscape accessibility and land cover change in Western Honduras, and demonstrates how these relationships are influenced by social and economic processes of land use change in the region. The study area presents a complex mosaic of land cover change processes that involve approximately equal amounts of reforestation and deforestation.

Upstream-to-downstream changes in nutrient export risk

Journal Articles & Books
Diciembre, 2003

Nutrient export coefficients are estimates of the mass of nitrogen (N) or phosphorus (P) normalized by area and time (e.g., kg/ha/yr). They have been estimated most often for watersheds ranging in size from 10² to 10⁴ hectares, and have been recommended as measurements to inform management decisions. At this scale, watersheds are often nested upstream and downstream components of larger drainage basins, suggesting nutrient export coefficients will change from one subwatershed to the next. Nutrient export can be modeled as risk where lack of monitoring data prevents empirical estimation.

Land use, land cover changes and coastal lagoon surface reduction associated with urban growth in northwest Mexico

Journal Articles & Books
Diciembre, 2003
México

Coastal land use and land cover changes, emphasizing the alterations of coastal lagoons, were assessed in northwest Mexico using satellite imagery processing. Supervised classifications of a Landsat series (1973–1997) and the coefficients Kappa (K) and Tau (τ), were used to assess the area and verify the accuracy of the classification of six informational classes (urban area, aquatic systems, mangrove, agriculture, natural vegetation, and aquaculture). Pixel-by-pixel change detection among dates was evaluated using the Kappa Index of Agreement (KIA).