ECONOMIC POLICIES FOR REGULATING AGRICULTURAL DRAINAGE WATER1

ABSTRACT: Agricultural drainage water is a major source of environmental pollution in many areas. This paper reviews the literature on the economics of nonpoint-source pollution and applies it to the regulation of agricultural drainage water. Four types of regulatory policies are considered. The empirical analysis is carried out for cotton production in the San Joaquin Valley of California. Variable inputs are the quantity of water applied and the type of irrigation system. All four policies can achieve economic efficiency under the conditions assumed here, but the policies differ in terms of the distributional impacts and administrative requirements.     

Long-term depletion of calcium and other nutrients in eastern US forests

Both harvest removal and leaching losses can deplete nutrient capital in forests, but their combined long-term effects have not been assessed previously. We estimated changes in total soil and biomass N, Ca, K, Mg, and P over 120 years from published data for a spruce-fir site in Maine, two northern hardwood sites in New Hampshire, central hardwood sites in Connecticut and Tennessee, and a loblolly pine site in Tennessee. For N, atmospheric inputs counterbalance the outputs, and there is little long-term change on most sites. For K, Mg, and P, the total pool may decrease by 2%–10% in 120 years depending on site and harvest intensity. For Ca, net leaching loss is 4–16 kg/ha/yr in mature forests, and whole-tree harvest removes 200–1100 kg/ha. Such leaching loss and harvest removal could reduce total soil and biomass Ca by 20%–60% in only 120 years. We estimated unmeasured Ca inputs from rock breakdown, root-zone deepening, and dry deposition; these should not be expected to make up the Ca deficit. Acid precipitation may be the cause of current high leaching of Ca. Although Ca deficiency does not generally occur now in acid forest soils, it seems likely if anthropogenic leaching and intensive harvest removal continue.     

Government expenditures on imported inputs and the goals of food self-sufficiency and food security in the Southern African Development Co-ordination Conference

Food security and food self-sufficiency are important regional goals for the Southern African Development Coordination Conference (SADCC). In the long run, success in these areas would reduce the incidence of drought-related mass starvation and the epidemic of malnutrition and undernutrition that exists among some tribal groups. For food production to improve, the governments must commit themselves to increasing the access of peasant farmers to critical agricultural inputs. If they do not take proper action in this area of development planning, domestic food production is likely to stagnate or decline. This study is a broad examination of the relationship between government expenditures on imported inputs and the performance of the domestic food subsector. Because much data on government spending and agricultural production in Africa are unavailable, and those in published form are of suspect validity, the study is undertaken largely as a conceptual overview. The empirical analyses are conducted, therefore, largely to provide a staging ground for the conceptual arguments.     

KALMAN FILTER CALCULATION OF SAMPLING FREQUENCY WHEN DETERMINING ANNUAL MEAN SOLUTE CONCENTRATIONS

ABSTRACT: A linear filter (Kalman filter) technique was used with a Streamflow-concentration model the minimize surface water quality sampling frequencies when determining annual mean solute concentrations with a predetermined allowable error. The Kalman filter technique used the stream discharge interval as a replacement for the more commonly used time interval. Using filter computations, the measurement error variance was minimized within the sample size constraints. The Kalman filter application proposed here is applicable only under several conditions including: monitoring is solely to estimate annual mean concentration; discharge measurement errors are negligible; the Streamflow-concentration model is valid; and monthly samples reflect the total variance of the solute in question.     

EFFECTS OF PLACER MINING DISCHARGE ON HEALTH AND FOOD OF ARCTIC GRAYLING1

ABSTRACT: During the summers of 1982, 1983, and 1985, we assessed the effects of placer mining sedimentation on Arctic grayling, Thymallus arcticus, in the headwaters of Birch Creek, northeast of Fairbanks, Alaska. We compared differences between two streams (one that was undisturbed and one with mining activity upstream) near the confluence. Studies of caged fish demonstrated that, if grayling could not escape from streams carrying mining sediments, they would either die at high rates (sac fry) or suffer gill damage, starvation, and slowed maturation (age-O fingerlings and age-2 juveniles). Indirect effects of sedimentation, through loss of summer habitat for feeding and reproduction, may more severely affect grayling populations than the direct effects of sedimentation on the health and survival of individual fish.     

A NEW LOOK AT FLOOD RISK DETERMINATION1

ABSTRACT: The probability distributions of annual peak flows used in flood risk analysis quantify the risk that a design flood will be exceeded. But the parameters of these distributions are themselves to a degree uncertain and this uncertainty increases the risk that the flood protection provided will in fact prove to be inadequate. The increase in flood risk due to parameter uncertainty is small when a fairly long record of data is available and the annual flood peaks are serially independent, which is the standard assumption in flood frequency analysis. But standard tests for serial independence are insensitive to the type of grouping of high and low values in a time series, which is measured by the Hurst coefficient. This grouping increases the parameter uncertainty considerably. A study of 49 annual peak flow series for Canadian rivers shows that many have a high Hurst coefficient. The corresponding increase in flood risk due to parameter uncertainty is shown to be substantial even for rivers with a long record, and therefore should not be neglected. The paper presents a method of rationally combining parameter uncertainty due to serial correlation, and the stochastic variability of peak flows in a single risk assessment. In addition, a relatively simple time series model that is capable of reproducing the observed serial correlation of flood peaks is presented.     

ESTIMATING THE WATER QUALITY BENEFITS FROM SOIL EROSION CONTROL1

ABSTRACT: A framework for estimating the water quality benefits from soil erosion was developed. The framework is based on the linkages between soil erosion and offsite damages. The linkages are: erosion on the field, movement of eroded materials to waterways, impact of discharged material on water quality parameters, impact of water quality changes on ability of water to provide economic services, and the economic value of the changes in water use. These linkages need to be modeled in order to estimate the water quality benefits from reductions in soil erosion. Methods for modeling each link on a geographic level, which enables the analyses of national soil conservation, were examined. Areas where data or models were found to be lacking include transport of sediment and nutrients to water systems, impact of discharged materials on water quality parameters, and impact of water quality on ability of water to provide economic services. An economic evaluation of 1983 soil conservation programs was presented as an example of how the framework could be used. A number of simplifying assumptions were made to represent links that could not be modeled with available data.     

CONFLICT ANALYSIS OF THE SHOAL LAKE SUBDWISION1

ABSTRACT: The techniques of conflict analysis derived from game theory were applied to the Shoal Lake water supply conflict in southeastern Manitoba, Canada. The issue of conflict is the desire of an Indian Band in the area to build cottage lots near the intake for water supply for the City of Winnipeg. The City of Winnipeg contends that such a development would seriously affect the quality of water supplied to the City, thereby increasing its treatment costs significantly. The four major players defined for the conflict are the City of Winnipeg, Indian Band No. 40, the Province of Manitoba, and the Federal Department of Indian and Northern Affairs. The results of the conflict analysis suggest that the introduction of the provincial and federal government into the conifict will not assist significantly in its resolution and that further progress on the resolution is unlikely until the results of Federal Environment Assessment Review office hearing become available.