River basin hydrosalinity modeling
ABSTRACT Tanji, K.K., (1981). River basin hydrosalinity modeling. Agric. Water Manage., 1981. Hydrologic-salinity modeling at the river sub-basin and basin spatial scales in the Western U.S.A. are evaluated. In the past two decades, significant advances have been made in basin hydrosalinity modeling. These models are providing increased understanding of the complexity of water and salt flows in large-scale systems. Most models, however, have been developed for specific problems and do not lend themselves for application to a wide variety of salinity problems. Much more work is needed in the areas of field verification of models and increasing their utility for management and policy-making decisions.
Calibration and verification of an irrigation return flow hydrosalinity model
SummaryA modified irrigation project model (first developed and tested in its original form by Tanji in 1977) is presented which evaluates the impacts of present as well as future alternative land and water resource management on the volume and salt concentration in the irrigation return flow. Modifications were necessary to fit more closely into the prevailing hydrologic and salinity conditions in the Ebro River Basin (Spain), and include the initial and final stored soil water, rim inflows from adjacent hydrologic systems and contributions of gypsum and soluble salts to salt loadings.The model (which requires a total of 25 input variables) was calibrated in a 4,000 ha irrigation project where the salinity problem is not serious (average ECe is 2.2 dS/m), although gypsum is present in large quantities. Results show that model calibration and verification were, respectively, within −2% and +13% of measured surface irrigation return flows (volume and TDS, total dissolved solids) from the 1982 (calibration) and 1983 (verification) hydrological years.The performed sensitivity analysis shows that the key parameter for minimizing salt loading (at present one ha yields about 20 t of salt per year) in irrigation return flows is an increase in water application efficiency (WAE), which presently is only 48%. This increase in WAE will not lead to a substantial rise in the TDS of return flows because of gypsiferous character of these soils.
Study on the gaseous emissions from a landfill
Abstract Emissions from landfills contain a variety of compounds, organic and inorganic, which can create problems with human health. Here we examine the pollutants methane, hydrogen sulphite, mercaptans, sulphur dioxide, nitrogen dioxide and certain volatile organic compounds (VOCs) that are expected to be found in landfill emissions, in order to assess the environmental impact on the surrounding area. Results indicate that the concentrations in the landfill itself are quite high and in most cases above the ambient air quality limits, while for the surrounding area they are low. The problem is created by H 2 S and the mercaptans which, although in low content, have a distinct odour and cause problems to the neighbouring dwellings.