The quality and quantity of residential stormwater runoff from a control, traditional, and low impact development (LID) watershed were compared in a paired watershed study. A traditional neighborhood was built using typical subdivision standards while a LID design was constructed with best management practices including grass swales, cluster housing, shared driveways, rain gardens, and a narrower pervious concretepaver road. Weekly, flow-weighted, composite samples of stormwater were analyzed for nitrate + nitrite-nitrogen (NO 3 + NO 2 -N), ammonia-nitrogen (NH 3 -N), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total suspended solids (TSS). Monthly composite samples were analyzed for total copper (Cu), lead (Pb), and zinc (Zn). Mean weekly storm flow increased (600x) from the traditional watershed in the postconstruction period. Increased exports of TKN, NO 3 + NO 2 -N, NH 3 -N, TP, Cu, Zn, and TSS in runoff were associated with the increased storm flow. Postconstruction storm flow in the LID watershed was reduced by 42% while peak discharge did not change from preconstruction conditions. Exports were reduced from the LID watershed for NH 3 -N, TKN, Pb, and Zn, while TSS and TP exports increased.

Stormwater Runoff Quality and Quantity From Traditional and Low Impact Development Watersheds

Low-input agricultural systems that do not rely on fertilizers may be more dependent on vesicular-arbuscular mycorrhizal [VAM] fungi than conventionally managed systems. We studied populations of spores of VAM fungi, mycorrhiza formation and nutrient utilization of maize (Zea mays L.) grown in moldboard plowed, chisel-disked or no-tilled soil under conventional and low-input agricultural systems. Maize shoots and roots were collected at four growth stages. Soils under low-input management had higher VAM fungus spore populations than soils under conventional management. Spore populations and colonization of maize roots by VAM fungi were higher in no-tilled than in moldboard plowed or chisel-disked soil. The inoculum potential of soil collected in the autumn was greater for no-till and chisel-disked soils than for moldboard plowed soils and greater for low-input than conventionally farmed soil. The effects of tillage and farming system on N uptake and utilization varied with growth stage of the maize plants. The effect of farming system on P use efficiency was significant at the vegetative stages only, with higher efficiencies in plants under low-input management. The effect of tillage was consistent through all growth stages, with higher P use efficiencies in plants under moldboard plow and chisel-disk than under no-till. Plants grown in no-tilled soils had the highest shoot P concentrations throughout the experiment. This benefit of enhanced VAM fungus colonization, particularly in the low-input system in the absence of effective weed control and with likely lower soil temperatures, did not translate into enhanced growth and yield.

Effect of tillage and farming system upon VAM fungus populations and mycorrhizas and nutrient uptake of maize

The report includes: the current water resource situation; the demand situation for water; the supply situation for water; comparison of projected demand and supply; economic, environmental, and social implications of projected supply and demand; opportunities to improve the management of water and related forest and rangeland resources; obstacles to improving the management of water and related forest and rangeland resources.

An analysis of the timber situation in the United States: 1989-2040

Vulnerability and risk evaluation of agricultural nitrogen pollution for Hungary's main aquifer using DRASTIC and GLEAMS models.

Quantification of soil loss is one of the greatest challenges in natural resources and environmental planning. Computer simulation models are becoming increasingly popular in predicting soil loss for various land use and management practices. In this study, three soil erosion prediction models — the Water Erosion Prediction Project (WEPP), the Erosion Productivity Impact Calculator (EPIC), and the Areal Nonpoint Source Watershed Environment Response Simulation (ANSWERS) were used for simulating soil loss and testing the capability of the models in predicting soil losses for three different tillage systems (ridge-till, chisel-plow, and no-till). For each model, the most sensitive model parameters were calibrated using measured soil erosion data. After calibration, models were run and predicted soil loss values were compared with the measured soil loss values. The measured soil erosion data were collected from an erosion experiment field of Kansas State University at Ottawa (Kansas), USA. Field experiments were conducted from 1995 to 1997 on small plots to measure runoff and soil losses under all three tillage systems. All three models were evaluated on the basis of individual event, total yearly, and mean event-based soil loss predictions. Results showed that all the three models performed reasonably well and the predicted soil looses were within the range of measured values. For ridge-till and chisel-plow systems, WEPP and ANSWERS gave better predictions than those by EPIC model. For no-till system, WEPP and EPIC predictions were better than those by ANSWERS. The overall results indicate that WEPP predictions were better than those by the other two models in most of the cases, and it can be used with reasonable degree of confidence for soil loss quantification for all the three tillage systems.

Soil loss predictions with three erosion simulation models

THE water pollution generated by nonpoint sources, from a nationwide perspective, can appear over-whelming. The sheer size of the land area involved, the vast number of activities that contribute to nonpont-source pollution, and the institutional considerations that come into play in managing nonpoint sources can lead to the feeling that the nonpoint problem is too big to address. But such is not the case.

What is required is a narrowing of focus on the problem. First, states must identify the most important water quality problems caused by nonpoint sources. Second, to maximize the effectiveness of limited funds, states must concentrate on a limited number of water bodies where there is potential for improvement if nonpoint sources are controlled and where other sources will not preclude such improvement. Third, states must identify the major types of nonpoint sources or land use activities within watersheds that contribute nonpoint pollutants to affected water bodies. Finally, states must determine exactly what types of best management practices (BMPs) are needed and where they should be located within watersheds.

Experience has shown that in many watersheds a significant percentage of the pollution load and consequent water quality problems come from limited portions of …

Carl F. Myers

Papers

Nonpoint sources of water pollution

A new nonpoint-source water pollution control challenge